424B5 1 tm268877d1_424b5.htm 424B5

As Filed Pursuant to Rule 424(b)(5)

Registration No. 333-278340

The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities and are not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

Subject to Completion, dated March 23, 2026

PRELIMINARY PROSPECTUS SUPPLEMENT

(To Prospectus Dated April 5, 2024)

Shares of Common Stock

Pre-Funded Warrants to Purchase up to Shares of Common Stock

Shares of Common Stock Underlying Pre-Funded Warrants

Common Warrants to Purchase up to Shares of Common Stock

Shares of Common Stock Underlying Common Warrants

Placement Agent Warrants to Purchase up to Shares of Common Stock

Shares of Common Stock Underlying Placement AgentWarrants

We are offering shares of our common stock, par value $0.01 per share, and common warrants to purchase up to shares of our common stock, or the common warrants, pursuant to this prospectus supplement and the accompanying prospectus. The combined public offering price for each share of common stock and accompanying common warrant to purchase one share of common stock is $ . The common warrants have an exercise price of $ per share, are exercisable immediately and will expire five years from the date of issuance. We are also offering the shares of our common stock that are issuable from time to time upon exercise of the common warrants.

We are also offering pre-funded warrants, or the pre-funded warrants, to purchase up to an aggregate of shares of common stock (and the shares of common stock issuable from time to time upon exercise of the pre-funded warrants), in lieu of shares of common stock, to those purchasers whose purchase of shares of common stock in this offering would result in the purchaser, together with its affiliates and certain related parties, beneficially owning more than 4.99% (or, at the election of the holder, 9.99%) of our outstanding shares of common stock following the consummation of this offering. A holder of pre-funded warrants will not have the right to exercise any portion of its pre-funded warrants if the holder, together with its affiliates and certain related parties, would beneficially own in excess of 4.99% (or, at the election of the holder, 9.99%) of the number of shares of common stock outstanding immediately after giving effect to such exercise. Each pre-funded warrant will be exercisable for one share of common stock at an exercise price of $0.01 per share of common stock. The combined public offering price is $ per pre-funded warrant and accompanying common warrant, which is equal to the combined public offering price per share of common stock and accompanying common warrant less $0.01. Each pre-funded warrant will be exercisable upon issuance and will expire when exercised in full. The shares of common stock or pre-funded warrants, as applicable, and the accompanying common warrants, can only be purchased together in this offering but will be issued separately and will be immediately separable upon issuance.

Our common stock is traded on The Nasdaq Capital Market under the symbol “OTLK.” On March 20, 2026, the last reported sale price of our common stock was $0.35 per share. There is no established public trading market for the common warrants or the pre-funded warrants, and we do not expect a market to develop. In addition, we do not intend to apply for listing of the common warrants or the pre-funded warrants on any securities exchange or recognized trading system.

The final public offering price will be determined between us and investors based on market conditions at the time of pricing, and may be at a discount to the current market price of our common stock.

We have retained H.C. Wainwright & Co., LLC to act as our exclusive placement agent, or the placement agent, in connection with the offering of the securities offered by this prospectus supplement. The placement agent has agreed to use its reasonable best efforts to arrange for the sale of the securities offered by this prospectus supplement. The placement agent is not purchasing or selling any of the securities that we are offering and the placement agent is not required to arrange the purchase or sale of any specific number of shares or dollar amount. We have agreed to pay to the placement agent the placement agent fees set forth in the table below, which assumes that we sell all of the securities offered by this prospectus supplement and accompanying prospectus. See “Plan of Distribution” in this prospectus supplement for more information regarding these arrangements.

We are a “smaller reporting company” under the federal securities laws and are subject to reduced public company reporting requirements. See the section entitled “Prospectus Supplement Summary—Implications of Being a Smaller Reporting Company.”

Investing in our securities involves a high degree of risk. Before making an investment decision, please read the information in “Risk Factors” beginning on page S-7 of this prospectus supplement and in our filings incorporated by reference into this prospectus supplement and the accompanying prospectus.

Per Share and
Accompanying
Common
Warrant

Per Pre-Funded
Warrant and
Accompanying
Common
Warrant

Total

Combined public offering price

Placement agent’s fees⁽¹⁾

Proceeds, before expenses, to us

(1) We have agreed to pay the placement agent a cash fee of 7.0% of the aggregate gross proceeds of this offering. Because there is no minimum offering amount required as a condition to closing in this offering, the actual public offering amount, placement agent fees, and proceeds to us, if any, are not presently determinable and may be substantially less than the total maximum offering amounts set forth above. In addition, we will pay the placement agent a management fee of 1.0% of the aggregate gross proceeds of this offering. We have also agreed to issue to the placement agent (or its designees) warrants to purchase a number of shares of common stock equal to 7.0% of the aggregate number of shares of common stock and pre-funded warrants sold in this offering, or the placement agent warrants, at an exercise price per share equal to 125% of the public offering price per share and accompanying common warrant to be sold in this offering. The registration statement of which this prospectus supplement and accompanying prospectus form a part also registers the offer and sale of these placement agent warrants and the shares of common stock issuable upon exercise of these placement agent warrants. In addition, we have agreed to pay certain expenses of the placement agent in connection with this offering. See “Plan of Distribution” in this prospectus supplement for a description of the compensation payable to the placement agent.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Delivery of the securities to investors is expected on or about , 2026.

H.C. Wainwright & Co.

Prospectus supplement dated , 2026.

TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

Page

ABOUT THIS PROSPECTUS SUPPLEMENT	S-ii
SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS	S-iv
PROSPECTUS supplement SUMMARY	S-1
RISK FACTORS	S-7
USE OF PROCEEDS	S-14
DILUTION	S-15
DESCRIPTION OF SECURITIES WE ARE OFFERING	S-17
PLAN OF DISTRIBUTION	S-20
MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES	S-24
LEGAL MATTERS	S-31
EXPERTS	S-31
WHERE YOU CAN FIND MORE INFORMATION	S-31
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE	S-32

PROSPECTUS

Page

ABOUT THIS PROSPECTUS	ii
PROSPECTUS SUMMARY	1
THE SECURITIES WE MAY OFFER	4
RISK FACTORS	7
SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS	8
USE OF PROCEEDS	9
DESCRIPTION OF CAPITAL STOCK	10
DESCRIPTION OF DEBT SECURITIES	16
DESCRIPTION OF WARRANTS	23
LEGAL OWNERSHIP OF SECURITIES	25
PLAN OF DISTRIBUTION	28
LEGAL MATTERS	30
EXPERTS	30
WHERE YOU CAN FIND MORE INFORMATION	30
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE	31

S-i

ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement and the accompanying prospectus relate to the offering of our securities. Before buying any of the securities that we are offering, we urge you to carefully read this prospectus supplement and the accompanying prospectus, together with the information incorporated by reference as described in the section titled “Incorporation of Certain Information by Reference” in this prospectus supplement and the accompanying prospectus and the information in any free writing prospectus that we may authorize for use in connection with this offering. These documents contain important information that you should consider when making your investment decision.

This document is in two parts. The first part is this prospectus supplement, which describes the terms of this offering of our securities and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus. The second part, the accompanying prospectus dated April 5, 2024, including the documents incorporated by reference therein, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in the accompanying prospectus or in any document incorporated by reference that was filed with the Securities and Exchange Commission, or the SEC, before the date of this prospectus supplement, on the other hand, you should rely on the information in this prospectus supplement. If any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in the accompanying prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.

Neither we nor the placement agent have authorized anyone to provide you with information different than or inconsistent with the information contained in or incorporated by reference into this prospectus supplement, the accompanying prospectus or in any free writing prospectus that we have authorized for use in connection with this offering. Neither we nor the placement agent take responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference into this prospectus supplement and the accompanying prospectus, and in any free writing prospectus that we have authorized for use in connection with this offering, is accurate only as of the date of those respective documents, regardless of the time of delivery of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus supplement, the accompanying prospectus, the documents incorporated by reference into this prospectus supplement and the accompanying prospectus, and any free writing prospectus that we have authorized for use in connection with this offering, in their entirety before making an investment decision regarding the securities we are offering. You should also read and consider the information in the documents to which we have referred you to in the section of this prospectus supplement entitled “Where You Can Find More Information” and “Incorporation of Certain Information by Reference.”

Except as otherwise indicated herein or as the context otherwise requires, references in this prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein to “Outlook,” “the company,” “we,” “us,” “our” and similar references refer to Outlook Therapeutics, Inc., a Delaware corporation, and its subsidiaries on a consolidated basis.

This prospectus supplement, the accompanying prospectus, and the information incorporated herein and therein by reference include trademarks, trade names and service marks owned by us or other companies. The Outlook logo, Oncobiologics logo, LYTENAVA and other trademarks or service marks of Outlook Therapeutics, Inc. appearing in this prospectus supplement, the accompanying prospectus, and the information incorporated herein and therein by reference are the property of Outlook Therapeutics, Inc. This prospectus supplement, the accompanying prospectus, and the information incorporated herein and therein by reference also contains registered marks, trademarks and trade names of other companies. All other trademarks, registered marks and trade names appearing in this prospectus supplement, the accompanying prospectus, and the information incorporated herein and therein by reference are the property of their respective holders.

S-ii

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus, the documents we have filed with the SEC that are incorporated by reference and any free writing prospectus that we have authorized for use in connection with this offering contain “forward-looking statements” within the meaning of Section 27A of the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. These statements relate to our future events, including our anticipated operations, research, development, manufacturing and commercialization activities, clinical trials, operating results and financial condition. These forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. Forward-looking statements may include, but are not limited to, statements about:

our ability to obtain and maintain regulatory approval for ONS-5010/LYTENAVA in the United States and other markets;

our ability to remedy the deficiencies identified in the most recent complete response letter issued by the FDA;

our ability to successfully commercialize and generate revenues from the sale of LYTENAVA™ (bevacizumab gamma) in the United Kingdom and European Union;

the rate and degree of market acceptance of our current and future product candidates, including our commercialization strategy and manufacturing capabilities for ONS-5010/LYTENAVA;

our ability to fund our working capital requirements, the sufficiency of our current cash resources and our need for additional funding;

our expectations regarding the potential market size and the size of the patient populations for our product candidates, if approved, for commercial use;

whether the results of our clinical trials will be sufficient to support domestic or global regulatory approvals;

the initiation, timing, progress and results of our clinical trials of our lead product candidate, ONS-5010/LYTENAVA;

our reliance on our contract manufacturing organizations and other vendors;

the implementation of our business model and strategic plans for our business and product candidates;

developments or disputes concerning our intellectual property or other proprietary rights;

our ability to maintain and establish collaborations or obtain additional funding;

our expectations regarding government and third-party payor coverage and reimbursement;

our ability to compete in the markets we serve;

the factors that may impact our financial results; and

the anticipated net proceeds from this offering.

In some cases, you can identify forward-looking statements by use of future dates or by terms such as: “anticipates,” “believes,” “continues,” “could,” “estimates,” “expects,” “intends,” “may,” “plans,” “seeks,” “should,” “will” and similar expressions intended to identify forward-looking statements. These statements reflect our current views with respect to future events, are based on assumptions and are subject to risks and uncertainties. Given these risks and uncertainties, you should not place undue reliance on these forward-looking statements. We discuss many of these risks in greater detail in “Risk Factors” contained on page S-7 of this prospectus supplement and under the section titled “Risk Factors” contained in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025, filed with the SEC on December 19, 2025, as updated by our subsequent filings, which are incorporated by reference into this prospectus supplement and the accompanying prospectus. Also, these forward-looking statements represent our estimates and assumptions only as of the date of the document containing the applicable statement. Unless required by law, we undertake no obligation to update or revise any forward-looking statements to reflect new information or future events or developments. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in such forward-looking statements. You should carefully read this prospectus supplement, the accompanying prospectus and the documents incorporated herein and therein by reference as described in the section titled “Incorporation of Certain Information by Reference” in this prospectus supplement completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements in the foregoing documents by these cautionary statements.

S-iii

PROSPECTUS supplement SUMMARY

This summary highlights selected information contained elsewhere in this prospectus supplement and the accompanying prospectus and in the documents we incorporate by reference. This summary does not contain all of the information you should consider before investing in our securities. You should read this entire prospectus supplement and the accompanying prospectus carefully, especially the risks of investing in our securities discussed under “Risk Factors” beginning on page S-7 of this prospectus supplement and under similar headings in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025, filed with the SEC on December 19, 2025, as updated by our subsequent filings, which are incorporated by reference in this prospectus supplement and accompanying prospectus, along with our consolidated financial statements and notes to those consolidated financial statements and the other information incorporated by reference in this prospectus supplement and the accompanying prospectus, before making an investment decision.

Company Overview

We are a biopharmaceutical company that has developed LYTENAVA^TM (bevacizumab gamma) as the first and only ophthalmic formulation of bevacizumab approved by the European Commission in the European Union, or EU, and the Medicines and Healthcare products Regulatory Agency, or MHRA, in the United Kingdom, or UK, for use in adults for the treatment of wet age-related macular degeneration, or wet AMD. In June 2025, we launched directly into the initial markets of Germany and the UK and are planning for launches in other EU countries either directly or with a licensing partner. Additionally, we are attempting to receive approval for ONS-5010/LYTENAVA by the U.S. Food and Drug Administration, or FDA, for the use of ONS-5010/LYTENAVA as a treatment for wet AMD in the United States. If approved in the U.S., our goal is to also launch directly in the United States as the first and only approved ophthalmic bevacizumab for the treatment of wet AMD. In addition to Europe and the United States, we may seek approval to launch the product in other markets outside of Europe and the U.S. either directly or with licensing partners.

Bevacizumab is a full-length, humanized anti-VEGF (Vascular Endothelial Growth Factor) recombinant monoclonal antibody, or mAb, that inhibits VEGF and associated angiogenic activity. Prior to the approval of ONS-5010/LYTENAVA in the EU and UK, bevacizumab had only been approved for use in the treatment of various forms of cancer and had not been optimized for use in the treatment of retina diseases. Because there previously were no approved bevacizumab products for the treatment of retinal diseases in the United States and other major markets, we submitted standard biologic therapeutic applications and are not using the biosimilar drug regulatory pathway that would be required if bevacizumab were an approved drug for the targeted disease. Off-label repackaged bevacizumab is a frequently used first-line anti-VEGF treatment in Europe (approximately 2.8 million injections annually) and the United States (approximately 2.7 million injections annually) based on data compiled from various sources (Citeline (2023), Global Data (2023) and Market Scope (2022); ASRS 2024 Membership Survey; Market Scope 2024 US Retina Quarterly Updates; GlobalData: Age-Related Macular Degeneration: Global Drug Forecast and Market Analysis to 2028 (April 2020)). We believe ONS-5010/LYTENAVA has potential to mitigate risks associated with off-label use of unapproved bevacizumab. We believe there is significant opportunity in Europe with a total anti-VEGF retina market estimated to be approximately $3.6 billion, including approximately 1.52 million treated patients and approximately 8.3 million total anti-VEGF units (Global Data (2023); Market Scope (2022); IQVIA MIDAS data Q3 2023; Graefe's Archive for Clinical and Experimental Ophthalmology (2020) 258:503–511). We similarly see significant opportunity in the United States, with an estimated $8.5 billion total anti-VEGF retina market, where 55% of physician state off-label repackaged bevacizumab is the preferred first-line product. It is estimated that 34% of the total anti-VEGF market is off-label bevacizumab (new and maintenance therapy) (Citeline (2023); Global Data (2023); Market Scope (2022); ASRS 2024 Membership Survey; Market Scope 2024 US Retina Quarterly Updates; GlobalData: Age-Related Macular Degeneration: Global Drug Forecast and Market Analysis to 2028 (April 2020)). We estimate the global market for anti-VEGF retina to be approximately $16 billion (Citeline (2023), Global Data (2023) and Market Scope (2022)).

In May 2024, the European Commission granted the Marketing Authorization for ONS-5010/LYTENAVA for the treatment of wet AMD in the EU. The decision applied automatically in all 27 EU Member States, and, within 30 days, also to Iceland, Norway and Liechtenstein. In July 2024, the MHRA granted marketing authorization for ONS-5010/LYTENAVA for the treatment of wet AMD in the UK under the new International Recognition Procedure, or IRP, which allows the MHRA to rely on an authorization received for the same product from one of MHRA’s specified Reference Regulators, or RRs, when considering an application for marketing authorization in the UK. ONS-5010/LYTENAVA is the first and only authorized ophthalmic formulation of bevacizumab for use in treating wet AMD in the EU and UK.

S-1

Separately, in March 2022, we submitted a BLA to the FDA for ONS-5010/LYTENAVA for the treatment of wet AMD. In May 2022, we voluntarily withdrew our BLA to provide additional information requested by the FDA. We re-submitted the BLA to the FDA for ONS-5010/LYTENAVA in August 2022, and in October 2022, we received confirmation from the FDA that our BLA had been accepted for filing. In August 2023, we received a Complete Response Letter, or CRL, in which the FDA concluded it could not approve the BLA during this review cycle due to several chemical, manufacturing and control, or CMC, issues, open observations from pre-approval manufacturing inspections, and a lack of substantial evidence. At subsequent Type A meetings with the FDA, we learned that the FDA required the completion of an additional adequate and well-controlled clinical trial evaluating ONS-5010/LYTENAVA, as well as additional requested CMC data indicated in the CRL to approve ONS-5010/LYTENAVA for use in wet AMD.

We agreed to conduct an additional adequate and well-controlled clinical trial following discussions with the FDA in support of our BLA for ONS-5010/LYTENAVA. In December 2023, we submitted a Special Protocol Assessment, or SPA, to the FDA for this study (NORSE EIGHT) seeking confirmation that, if successful, it would address the FDA’s requirement for a second adequate and well-controlled clinical trial to support our planned resubmission of the ONS-5010/LYTENAVA BLA. In January 2024, we received confirmation that the FDA had reviewed and agreed upon the NORSE EIGHT trial protocol pursuant to the SPA. In November 2024, we reported that ONS-5010/LYTENAVA did not meet the pre-specified non-inferiority endpoint at week 8 set forth in the SPA. Analysis of the complete week 12 data set for NORSE EIGHT provided additional evidence of improvement in vision and biological activity. We resubmitted the BLA for ONS-5010/LYTENAVA in February 2025. On August 27, 2025, we received a second CRL from the FDA. This CRL included only one deficiency, for a lack of substantial evidence of effectiveness. In the CRL, the FDA advised that, because ONS-5010 did not meet the primary efficacy endpoint in NORSE EIGHT, it was recommended that confirmatory evidence of efficacy be submitted to support the application for ONS-5010. Additionally, the FDA reiterated that NORSE TWO met its primary endpoint for effectiveness. Following a September 2025 Type A meeting with the FDA, we resubmitted the BLA in October 2025. On December 31, 2025, we reported that we had received a third CRL in which the FDA noted that the additional mechanistic and natural history data information provided in the BLA resubmission does not alter the previous review conclusion that while the one adequate and well-controlled study demonstrated efficacy, and the FDA has again recommended that confirmatory evidence of efficacy be submitted to support the application. However, the FDA did not indicate in the CRL what type of confirmatory evidence would be acceptable. In March 2026, we conducted a Type A meeting with the FDA to discuss the CRL and potential regulatory pathways for ONS-5010. If approved, we expect to receive 12 years of regulatory exclusivity in the United States.

Risks Associated with Our Business

Our business is subject to a number of risks of which you should be aware before making an investment decision. These risks are discussed more fully in the “Risk Factors” section of this prospectus supplement immediately following this prospectus supplement summary and in the “Risk Factors” sections in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025, filed with the SEC on December 19, 2025, as updated by our subsequent filings which are incorporated by reference in this prospectus supplement and accompanying prospectus. These risks include the following:

We have incurred significant losses and negative cash flows from operations since our inception and expect to continue to incur significant losses and negative cash flows from operations for at least the next 12 months;

We have generated minimal revenue from product sales to date and have not generated material revenue from the sales of any product and may never be profitable;

	·	There is substantial doubt about our ability to continue as a going concern. We will need to raise substantial additional funding to complete the development and commercialization of ONS-5010/LYTENAVA™ (bevacizumab-gamma) outside of the EU and UK and support our operations until we are able to generate sufficient revenue from the sales of ONS-5010/LYTENAVA in the EU and UK. This additional funding may not be available on acceptable terms or at all. Failure to obtain this necessary capital when needed may force us to delay, limit or terminate our product development efforts or other operations;

	·	Raising additional capital, including modifications to our existing convertible securities, may cause dilution to our securityholders, restrict our operations or require us to relinquish rights to our technologies or product candidates;

	·	We may be unable to remedy the deficiencies identified in the most recent complete response letter issued by the FDA;

	·	We may need to enter into alliances with other companies that can provide capabilities and funds for the development and commercialization of product candidates. If we are unsuccessful in forming or maintaining these alliances on favorable terms, our business could be harmed;

	·	Due to our limited resources and access to capital, we have, and will continue to need to, prioritize development of certain product candidates, and these decisions may prove to have been wrong and may harm our business;

	·	Clinical drug development is a lengthy and expensive process and we may encounter substantial delays in our clinical trials or may fail to demonstrate safety and efficacy to the satisfaction of applicable regulatory authorities;

S-2

The development and commercialization of pharmaceutical products is subject to extensive regulation, and we may not obtain regulatory approvals for ONS-5010/LYTENAVA outside of the EU and UK or in any other indications for which we plan to develop the product, or any future product candidates, on a timely basis or at all;

Any delays in the commencement or completion, or termination or suspension, of our planned or future clinical trials could result in increased costs to us, delay or limit our ability to generate revenue and adversely affect our commercial prospects;

We face intense competition and rapid technological change and the possibility that our competitors may develop therapies that are similar, more advanced or more effective than ours. Other products may be approved and successfully commercialized before ours, which may adversely affect our business and financial condition;

We currently have no marketing and sales organization. If we are unable to establish and maintain sales and marketing capabilities in jurisdictions for which we choose to retain commercialization rights, we may be unable to generate any revenue and will depend on the efforts of our licensing partners, if any;

We rely on third parties to manufacture and test ONS-5010/LYTENAVA, conduct our preclinical and clinical trials and perform other tasks for us. If these third parties do not successfully carry out their contractual duties, meet expected deadlines or comply with regulatory requirements, we may not be able to obtain regulatory approval for ONS-5010/LYTENAVA outside the EU and UK, or for any other of our product candidates, or commercialize ONS-5010/LYTENAVA or any other of our product candidates and our business could be harmed;

We currently engage single source suppliers for clinical trial services, drug substance manufacturing, and fill-finish manufacturing of ONS-5010/LYTENAVA. The loss of any of these suppliers, or any future single source suppliers, could harm our business;

If we infringe or are alleged to infringe intellectual property rights of third parties, our business could be harmed;

If we are unable to obtain and maintain effective patent rights for ONS-5010/LYTENAVA or our other product candidates or any future product candidates, we may not be able to prevent competitors from using technologies we consider important in the development and commercialization of ONS-5010/LYTENAVA or any future product candidates, resulting in loss of any potential competitive advantage our patents may have otherwise afforded us;

If we fail to comply with our obligations in the agreements under which we license intellectual property and other rights from third parties or otherwise experience disruptions to our business relationships with our licensors, we could lose license rights that are important to our business;

Unfavorable global economic and political conditions could adversely affect our business, financial condition or results of operations;

We are highly dependent on the services of our key executives and personnel, and if we are not able to retain these members of our management or recruit additional management, clinical and scientific personnel, our business will suffer;

We and certain of our current and former officers have been named as defendants in a pending securities class action lawsuit. Certain of our current and former officers and directors have also been named as defendants in a pending shareholder derivative action. These lawsuits, and potential similar or related lawsuits, could result in substantial damages, divert management’s time and attention from our business, and have a material adverse effect on our results of operations; and

The trading price of our securities is likely to be volatile, and purchasers of our securities could incur substantial losses.

S-3

Our Intellectual Property

Our commercial success depends in part on our ability to avoid infringing the proprietary rights of third parties, our ability to obtain and maintain proprietary protection for our technologies where applicable and to prevent others from infringing our proprietary rights. We seek to protect our proprietary technologies by, among other methods, evaluating relevant patents, establishing defensive positions, monitoring EU oppositions and pending intellectual property rights, preparing litigation strategies in view of the U.S. legislative framework and filing United States and international patent applications on technologies, inventions and improvements that are important to our business. As of March 20, 2026, we own three U.S. patents, and twenty-four foreign patents, which relate to formulations developed for our legacy biosimilar program ONS-3010 and ONS-5010/ONS-1045, methods of antibody purification, methods for purifying antibodies to separate isoforms, methods of use, methods of reducing high molecular weight species, and modulating afucosylated species as well as efficiently determining the amino acid sequence of antibodies. Our Patent Cooperation Treaty, or PCT, Application No. PCT/US2017/016040, was filed in 2017. A U.S. patent in this family is granted and expected to expire no earlier than 2037. Our PCT Application No. PCT/US2017/012349, was filed in 2017. Patents are granted in Australia and Japanese patent are granted and expected to expire no earlier than 2037. Our Application No. PCT/US2016/068847 was filed in 2016. Patents in this family are granted in Germany, United Kingdom, India, and Japan, and expected to expire no earlier than 2036. Our PCT Application No. PCT/US2016/014252 was filed in 2016. Patents in this family are granted in Germany, United Kingdom, and the U.S., and expected to expire no earlier than 2036. Our PCT Application No. PCT/US2017/016549 was filed in 2017. Patents in this family are granted in India and Japan, and expected to expire no earlier than 2037. We also rely on trade secrets, know-how and continuing technological innovation to develop and maintain our proprietary position.

The term of individual patents depends upon the legal term of the patents in countries in which they are obtained. In most countries, including the United States, the patent term is generally 20 years from the earliest date of filing a non-provisional patent application in the applicable country. In the United States, a patent’s term may, in certain cases, be lengthened by patent term adjustment, which compensates a patentee for administrative delays by the United States Patent and Trademark Office in examining and granting a patent or may be shortened if a patent is terminally disclaimed over a commonly owned patent or a patent naming a common inventor and having an earlier expiration date.

Company Information

We initially incorporated in January 2010 in New Jersey as Oncobiologics, Inc., and in October 2015, we reincorporated in Delaware by merging with and into a Delaware corporation. In November 2018, we changed our name to Outlook Therapeutics, Inc. Our headquarters are located at 111 S. Wood Avenue, Unit #100, Iselin, New Jersey 08830, and our telephone number at that location is (609) 619-3990. Our website address is www.outlooktherapeutics.com. The information contained on, or that can be accessed through, our website is not part of, and is not incorporated by reference into this prospectus supplement or the accompanying prospectus, and you should not consider it part of this prospectus supplement or the accompanying prospectus. Our website address is included in this prospectus supplement as an inactive textual reference only.

Implications of Being a Smaller Reporting Company

We are a “smaller reporting company” as defined in Item 10(f)(1) of Regulation S-K. Smaller reporting companies may take advantage of certain reduced disclosure obligations, including, among other things, providing only two years of audited financial statements and reduced disclosure obligations regarding executive compensation. To the extent we take advantage of any reduced disclosure obligations, it may make the comparison of our financial statements with other public companies difficult or impossible.

S-4

THE OFFERING

Common stock offered by us		shares.

Pre-funded warrants offered by us		Pre-funded warrants to purchase up to shares of our common stock. Each pre-funded warrant will have an initial exercise price per share of $0.01, subject to certain adjustments. The purchase price of each pre-funded warrant and accompanying common warrant is equal to the price at which the share of our common stock and accompanying common warrant is being sold in this offering, minus $0.01. The pre-funded warrants are exercisable immediately and may be exercised at any time until all of the pre-funded warrants are exercised in full. For more information, see the section titled “Description of Securities We Are Offering—Pre-Funded Warrants” on page S-18 of this prospectus supplement. This prospectus supplement also relates to the offering of the shares of our common stock issuable upon exercise of the pre-funded warrants.

Common warrants offered by us		Common warrants to purchase up to shares of our common stock. Each common warrant will have an initial exercise price per share of $ , subject to certain adjustments, will become exercisable immediately, and will expire five years from the date of issuance. For more information, see the section titled “Description of Securities We Are Offering—Common Warrants” on page S-17 of this prospectus supplement. This prospectus supplement also relates to the offering of the shares of our common stock issuable upon exercise of the common warrants.

Placement agent warrants		We have also agreed to issue to the placement agent (or its designees) warrants to purchase a number of shares of common stock equal to 7.0% of the aggregate number of shares of common stock and pre-funded warrants sold in this offering at an exercise price equal to $ , which is 125% of the combined public offering price per share of common stock and accompanying common warrant. The placement agent warrants will be exercisable upon issuance. The placement agent warrants will expire five years from the commencement of sales under this offering. For more information, see the section titled “Description of Securities We Are Offering—Placement Agent Warrants” on page S-19 of this prospectus supplement. This prospectus supplement also relates to the offering of these placement agent warrants and the shares of our common stock issuable upon exercise of the placement agent warrants.

Common stock to be outstanding immediately after this offering		shares (assuming none of the common warrants or pre-funded warrants issued in this offering are exercised).

Use of proceeds		We estimate that net proceeds from this offering, excluding the proceeds, if any, from the exercise of the common warrants or the pre-funded warrants offered hereby, will be approximately $ million, after deducting placement agent fees and estimated offering expenses payable by us if we sell the maximum amount of securities offered hereby. However, because this is a best efforts offering and there is no minimum offering amount required as a condition to the closing of this offering, the actual offering amount, the placement agent fees and net proceeds to us are not presently determinable and may be substantially less than the maximum amounts set forth on the cover page of this prospectus supplement. We intend to use the net proceeds from this offering, together with our cash and cash equivalents, for working capital and general corporate purposes. See “Use of Proceeds” for additional information.

Risk factors		Investing in our securities involves a high degree of risk. Before making an investment decision, please read the information contained in and incorporated by reference in this prospectus supplement and the accompanying prospectus under the section titled “Risk Factors” beginning on page S-7 of this prospectus supplement.

Nasdaq Capital Market symbol		Our common stock is listed on The Nasdaq Capital Market under the symbol “OTLK.” There is no established public trading market for the common warrants or the pre-funded warrants and we do not expect a market to develop. In addition, we do not intend to apply for listing of the common warrants or the pre-funded warrants on any securities exchange or recognized trading system.

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The number of shares of our common stock to be outstanding after this offering is based on 84,614,219 shares of our common stock outstanding as of March 20, 2026. This excludes the number shares of common stock issuable upon exercise of the pre-funded warrants and common warrants being sold in this offering and the placement agent warrants, and also excludes the following:

6,670,881 shares of common stock issuable upon exercise of outstanding stock options granted under our 2024 Equity Incentive Plan, or the 2024 Plan, as of March 20, 2026, with a weighted-average exercise price of $6.56 per share;

1,573,065 shares of common stock reserved for future issuance under the 2024 Plan as of March 20, 2026;

47,407 shares of common stock reserved for future issuance under our 2016 Employee Stock Purchase Plan, or the ESPP, as of March 20, 2026, as well as any future automatic annual increases in the number of shares of common stock reserved for issuance under the ESPP;

35,428,913 shares of common stock issuable upon exercise of outstanding warrants as of March 20, 2026 with a weighted-average exercise price of $3.03 per share;

23,893,641 shares of common stock which may be issuable upon the conversion of the March 2025 Note (as defined in “Risk Factors—Risks Related to this Offering”), which had an outstanding principal balance and accrued interest of approximately $9.7 million as of March 20, 2026 and a conversion price of $0.404; and

Up to approximately $62.0 of shares of our common stock remaining to be sold under under an “at the market” equity offering program that we entered into pursuant to our At-the-Market Sale Agreement, dated May 16, 2023, as amended, with BTIG LLC, as agent, or the Sales Agreement, as of March 20, 2026.

Unless otherwise indicated, all information in this prospectus supplement assumes:

no exercise of outstanding options or warrants to purchase our common stock;

no issuance of shares available, or that may become available, for future issuance under our equity compensation plans; and

no exercise of the common warrants or the pre-funded warrants offered in this offering or the placement agent warrants.

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RISK FACTORS

Investing in our securities involves a high degree of risk. Before you decide to invest in our securities, you should carefully consider the following risk factors and the risk factors discussed under the section titled “Risk Factors” contained in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025, filed with the SEC on December 19, 2025, as updated by our subsequent filings, which are incorporated by reference into this prospectus supplement and accompanying prospectus in their entirety, together with all of the other information contained in this prospectus supplement and the accompanying prospectus or incorporated by reference into this prospectus supplement and the accompanying prospectus. The risks and uncertainties described in these documents are not the only ones we face. Other risks and uncertainties, including those that we do not currently consider material, may impair our business. If any of the risks discussed below or incorporated by reference actually occur, our business, financial condition, operating results or cash flows could be materially adversely affected. This could cause the value of our securities to decline, and you may lose all or part of your investment.

Risks Related to this Offering

There is substantial doubt about our ability to continue as a going concern, which substantial doubt will not be alleviated with the net proceeds of this offering. We will continue to need to raise substantial additional funding to complete the development of ONS-5010/LYTENAVA outside the EU and UK and support our operations until we are able to generate sufficient revenue from the sales of ONS-5010/LYTENAVA in the EU and UK. This additional funding may not be available on acceptable terms or at all. Failure to obtain this necessary capital when needed may force us to delay, limit or terminate our product development efforts or other operations.

Developing product candidates is an expensive, risky and lengthy process. We have received a marketing authorization from the European Commission and the MHRA for ONS-5010/LYTENAVA for the treatment of wet AMD in the EU and UK, respectively. We are currently advancing ONS-5010/LYTENAVA through the regulatory approval process in the United States, which may ultimately require additional clinical and/or non-clinical studies. Our expenses may increase in connection with our ongoing activities, particularly as we continue the research and development of, continue and initiate clinical trials of, and seek marketing approval for, ONS-5010/LYTENAVA outside the EU and UK.

As of December 31, 2025, our cash and cash equivalents balance was $8.7 million. We estimate that our cash and cash equivalents as of December 31, 2025, together with the estimated net proceeds of this offering and $2.4 million in net proceeds from the sale of shares of common stock under the Sales Agreement since December 31, 2025, will only be sufficient to fund our operations into . On March 13, 2025, we issued a $33.1 million promissory note, or the March 2025 Note, to Avondale Capital, LLC, or Avondale. The March 2025 Note bears interest at the prime rate plus 3%, with a minimum rate of 9.5%, and is convertible into common stock. We must repay at least $3.0 million (by cash or conversions into common stock) of the outstanding balance on the March 2025 Note each quarter starting in the second calendar quarter of 2025 (subject to adjustments for conversions and to payment of a 7.5% exit fee), or the Quarterly Debt Reduction Obligations. Any amount converted by Avondale during a given calendar quarter in excess of the Quarterly Debt Reduction Obligations will be credited toward meeting the Quarterly Debt Reduction Obligations for the next quarter or quarters. See “Raising additional capital, including as a result of this offering or modifications to our existing convertible securities, may cause dilution to our securityholders, restrict our operations or require us to relinquish rights to our technologies or product candidates” for additional information on the terms of the March 2025 Note. On December 31, 2025, we did not satisfy the required $3.0 million Quarterly Debt Reduction Obligation, which constituted a Major Trigger Event under the March 2025 Note. As of March 20, 2026, Avondale had converted $6.9 million of principal and accrued interest on the March 2025 Note into shares of common stock at a weighted average conversion price of $0.46. While this Major Trigger Event has not resulted in an event of default under the March 2025 Note, as a result of our financial position, we may be unable to satisfy our future repayment obligations under the March 2025 Note, which could result in continued conversions at prices significantly below the initial $2.26 conversion price or, ultimately, an event of default, in which case Avondale could accelerate our obligations, and otherwise pursue remedies available to it, under the March 2025 Note. On March 16, 2026, we entered into a Note Purchase Agreement with Atlas Sciences, LLC, or Atlas, pursuant to which we agreed to issue to Atlas an unsecured promissory note with an original principal balance of $18.36 million , or the March 2026 Note, which we agreed to use for the partial repayment of $17 million of the March 2025 Note. As of March 20, 2026, there were approximately $9.7 million in remaining obligations under the March 2025 Note. In connection with entry into the Note Purchase Agreement with Atlas, we and Avondale entered into an an amendment to the March 2025 Note to extend the maturity thereof to December 31, 2026.

S-7

We do not believe our cash and cash equivalents will be adequate to fund our currently planned operations through at least the next 12 months from the date of our Quarterly Report on Form 10-Q for the quarter ended December 31, 2025. As a result, there is substantial doubt about our ability to continue as a going concern. We will require substantial additional capital to continue to operate as a going concern, which substantial doubt will not be alleviated with the net proceeds of this offering. Although we continue to pursue discussions with additional potential strategic partners for ONS-5010/LYTENAVA outside of the United States, there is no guarantee that we will be successful in reaching any such agreement, nor that such agreement, if successful, will cover the anticipated commercialization costs for ONS-5010/LYTENAVA. Moreover, on December 31, 2025, we reported that we had received a third CRL with respect to our BLA for ONS-5010, and the FDA has again recommended that confirmatory evidence of efficacy be submitted to support the application. However, the FDA did not indicate in the CRL what type of confirmatory evidence would be acceptable, and it is possible that we may need to conduct additional clinical and/or non-clinical studies of ONS-5010 in order to satisfy the FDA’s requirements, which would require substantial resources, which may be difficult to obtain or which may be unavailable to us on acceptable terms or at all. Our operating plan may also change as a result of many factors currently unknown to us, and, subject to the lock-up agreement we entered into in connection with this offering as described under “Plan of Distribution,” we will continue to actively seek substantial additional capital following this offering, through public or private equity or debt financings, third-party funding, marketing and distribution arrangements, as well as through other collaborations, strategic alliances and licensing arrangements, or a combination of these approaches. Even if we believe we have sufficient funds for our current or future operating plans, we may seek additional capital if market conditions are favorable or if we have specific strategic considerations. Additionally, we may not achieve the expected benefits of these cost reduction measures and other cost reduction plans on the anticipated timeline, or at all, which could otherwise accelerate our liquidity needs and could force us to further curtail or suspend our operations. If we are unable to obtain the substantial additional funding needed to operate our business, our business and prospects would be materially and adversely affected, and we may be required to cease operations entirely, liquidate all or a portion of our assets, and/or seek protection under the U.S. Bankruptcy Code, and you may lose all or part of your investment.

Any additional fundraising efforts may divert our management from their day-to-day activities, which may adversely affect our ability to develop and commercialize our product candidates. In addition, we cannot guarantee that future financing will be available in sufficient amounts or on terms acceptable to us, if at all. We may experience difficulties in accessing the capital markets due to external factors beyond our control, such as volatility in the equity markets for emerging biotechnology companies and general economic and market conditions both in the United States and abroad. For example, our ability to raise additional capital may be adversely impacted by global economic conditions and disruptions to and volatility in the credit and financial markets in the United States and worldwide, such as has been experienced recently due in part to, among other things, the impacts of inflation, geopolitical instability and uncertainty, and disruptions in access to bank deposits and lending commitments due to bank failure. In addition, our financial position may make it more difficult for us to secure additional funding. We cannot be certain that we will be able to obtain financing on terms acceptable to us, or at all. Our failure to obtain adequate and timely funding will adversely affect our business and our ability to develop our technology and products candidates. Moreover, the terms of any financing may negatively impact the holdings or the rights of our stockholders, and the issuance of additional securities, whether equity or debt, by us or the possibility of such issuance may cause the market price of our securities to decline. The incurrence of indebtedness could result in increased fixed payment obligations, and we may be required to agree to certain restrictive covenants, such as limitations on our ability to incur additional debt, limitations on our ability to acquire, sell or license intellectual property rights and other operating restrictions that could adversely impact our ability to conduct our business. We may be required to relinquish rights to some of our technologies or product candidates or otherwise agree to terms unfavorable to us, in order to obtain necessary funding, any of which may harm our business, operating results and prospects. Even if we believe we have sufficient funds for our current or future operating plans, we may seek additional capital if market conditions are favorable or for specific strategic considerations. If we are unable to obtain funding on a timely basis, we may be required to significantly curtail, delay or discontinue one or more of our development programs or the commercialization of ONS-5010/LYTENAVA or any product candidates, if approved. We may also be unable to expand our operations or otherwise capitalize on our business opportunities, as desired, which could harm our business, financial condition and results of operations.

S-8

Raising additional capital, including as a result of this offering or modifications to our existing convertible securities, may cause dilution to our securityholders, restrict our operations or require us to relinquish rights to our technologies or product candidates.

Until such time, if ever, as we can generate sufficient product revenues, we expect to finance our cash needs through a combination of equity and debt financings, as well as selectively continuing to enter into collaborations, strategic alliances and licensing arrangements. We do not currently have any committed external source of funding. To the extent that we raise additional capital through the sale of equity, including in this offering or via our Sales Agreement, or convertible debt securities, your ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect your rights as a securityholder.

We are obligated to repay a minimum of $3.0 million of the outstanding balance of the March 2025 Note each calendar quarter starting with the second calendar quarter of 2025, subject to adjustments for conversions by Avondale and the payment of an exit fee of 7.5%. Any amount converted by Avondale during a given calendar quarter in excess of the Quarterly Debt Reduction Obligations will be credited toward meeting the Quarterly Debt Reduction Obligations for the next quarter or quarters.

Avondale may convert any portion of the March 2025 Note into common stock at a conversion price of $2.26, as further described in the March 2025 Note. In addition, we may convert the March 2025 Note if our stock trades at or above $3.00 per share for 30 consecutive days with an average daily trading volume of at least $1.0 million. Trigger Events (e.g., payment default, covenant breaches) may increase the March 2025 Note balance by 5-10%. Unresolved issues after 10 trading days trigger default, accelerating the March 2025 Note with 22% interest. If the Conversion Price drops below $0.404, conversions must be paid in cash. Conversions of amounts outstanding under the March 2025 Note may result in the issuance of a substantial number of shares of common stock. On December 31, 2025, we did not satisfy the required $3.0 million Quarterly Debt Reduction Obligation, which constituted a Major Trigger Event under the March 2025 Note. As of March 20, 2026, Avondale had converted $6.9 million of principal and accrued interest on the March 2025 Note into shares of common stock at a weighted average conversion price of $0.46. If we are unable to satisfy future repayment obligations under the March 2025 Note, Avondale may continue to effectuate conversions at prices significantly below the initial $2.26 conversion price, with such conversion price to be determined in accordance with the terms set out in the March 2025 Note. Such conversion could result in significant dilution.

Additional debt financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends, and may be secured by all or a portion of our assets. If we secure development funds for ONS-5010/LYTENAVA or any future product candidate through entering into collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish additional valuable rights to our technologies, future revenue streams, research programs or product candidates or to grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds when needed, we may be required to delay, limit, reduce or terminate our product development or commercialization efforts, including for ONS-5010/LYTENAVA, or grant rights to develop and market ONS-5010/LYTENAVA or other product candidates that we would otherwise prefer to develop and market ourselves, terminate product development or future commercialization efforts, including for ONS-5010/LYTENAVA, or to cease operations altogether.

The trading price of our securities is likely to be volatile, and purchasers of our securities could incur substantial losses.

The market price of our securities has been and will likely continue to be volatile. The stock market in general and the market in which we operate have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. As a result of this volatility, investors may not be able to sell their securities at a profit. The market price of our securities could be subject to wide fluctuations in response to a variety of factors, including but not limited to:

	·	the success of competitive services, products or technologies;
	·	adverse results or delays in preclinical or clinical trials;

S-9

	·	any inability to obtain additional funding;
	·	any delay in filing an investigational new drug application, or IND, BLA or other regulatory submission for ONS-5010/LYTENAVA, or any of our product candidates when planned, and any adverse development or perceived adverse development with respect to the applicable regulatory agency’s review of that IND, BLA or other regulatory submission;
	·	the perception of limited market sizes or pricing for ONS-5010/LYTENAVA or any of our other product candidates;
	·	failure to successfully develop and commercialize ONS-5010/LYTENAVA or any of our other product candidates;
	·	post-marketing safety issues relating to our product candidates generally;
	·	failure to maintain our existing strategic collaborations or enter into new collaborations;
	·	failure by us or our licensors and strategic collaboration partners to prosecute, maintain or enforce our intellectual property rights;
	·	changes in laws or regulations applicable to our products;
	·	any inability to obtain adequate product supply for our product candidates or the inability to do so at acceptable prices;
	·	adverse regulatory decisions;
	·	introduction of new products, services or technologies by our competitors;
	·	failure to meet or exceed financial projections we may provide to the public;
	·	failure to meet or exceed the financial projections of the investment community;
	·	the perception of the pharmaceutical industry by the public, legislatures, regulators and the investment community;
	·	announcements of significant acquisitions, strategic partnerships, joint ventures or capital commitments by us, our strategic collaboration partners or our competitors;
	·	disputes or other developments relating to proprietary rights, including patents, litigation matters and our ability to obtain patent protection for our technologies;
	·	additions or departures of key scientific or management personnel;
	·	significant lawsuits, including stockholder litigation and litigation filed by us or filed against us pertaining to patent infringement or other violations of intellectual property rights;
	·	the outcomes of any citizens petitions filed by parties seeking to restrict or limit the approval of ONS-5010/LYTENAVA in the EU or UK, or any of our product candidates that may be approved;
	·	if securities or industry analysts do not publish research or reports about our business or if they issue an adverse or misleading opinion regarding our stock;
	·	changes in the market valuations of similar companies;
	·	general economic, industry or market conditions;
	·	sales of our securities by us or our stockholders in the future;
	·	trading volume of our securities;
	·	issuance of patents to third parties that could prevent our ability to commercialize our product candidates;
	·	the loss of one or more employees constituting our leadership team;
	·	changes in regulatory requirements that could make it more difficult for us to develop our product candidates; and
	·	the other factors described in this “Risk Factors” section or the “Risk Factors” section of our Annual Report on Form 10-K for the fiscal year ended September 30, 2025, filed with the SEC on December 19, 2025, as updated by our subsequent filings, which are incorporated by reference into this prospectus supplement and accompanying prospectus.

We and two of our current and former officers have been named as defendants a class action lawsuit filed in the United States District Court for the District of New Jersey and certain of our current and former officers and directors were named as defendants in a shareholder derivative action filed in the District Court of the District of Delaware. Such lawsuits have often been instituted against companies, including us, whose securities have experienced periods of volatility in market price. The pending lawsuits and any lawsuits brought against us in the future could result in substantial costs, which would hurt our financial condition and results of operations and divert management’s attention and resources, which could preclude or delay commercialization efforts.

S-10

In addition, biopharmaceutical companies in particular have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies. Broad market and industry factors may negatively affect the market price of our securities, regardless of our actual operating performance.

Our common stock may be delisted from The Nasdaq Capital Market and begin trading in the over-the-counter markets if we are not successful in regaining compliance with Nasdaq’s continued listing standards, which may negatively impact the price of our common stock and our ability to access the capital markets.

On February 18, 2026, we received a letter from the Listing Qualifications Staff, or the Nasdaq Staff, of The Nasdaq Stock Market LLC, or Nasdaq, notifying us that for the last 30 consecutive business days, the bid price of our common stock had closed below $1.00 per share, the minimum closing bid price required by the continued listing requirements of Nasdaq Listing Rule 5550(a)(2).

In accordance with Nasdaq Listing Rule 5810(c)(3)(A), we have a period of 180 calendar days, or until August 17, 2026, or the Compliance Date, to regain compliance with the minimum bid price requirement. To regain compliance, the closing bid price of our common stock must be at least $1.00 per share for a minimum of ten consecutive business days before the Compliance Date. If we do not achieve compliance by the Compliance Date, we may be eligible for an additional 180-day period to regain compliance if we meet the continued listing requirement for market value of publicly held shares and all other initial listing standards, with the exception of the bid price requirement, and provide written notice to Nasdaq of our intention to cure the deficiency during the second compliance period, by effecting a reverse stock split, if necessary. However, if it appears to the Nasdaq Staff that we will not be able to cure the deficiency, or if we are otherwise not eligible for the additional compliance period, and we do not regain compliance by the Compliance Date, The Nasdaq Capital Market will provide written notification to us that our common stock is subject to delisting. At that time, we may appeal the delisting determination to a hearings panel pursuant to the procedures set forth in the applicable Nasdaq listing rules. However, there can be no assurance that, if we do appeal the delisting determination by Nasdaq to the panel, such appeal would be successful.

We intend to actively monitor the closing bid price of our common stock between now and the Compliance Date and will evaluate available options to resolve the deficiency and regain compliance with the minimum bid price rule.

If we are not successful in regaining compliance, we anticipate that our common stock would begin trading on the over-the-counter market. Delisting from Nasdaq and trading on the over-the-counter market could adversely affect the liquidity of our common stock. Stocks traded on the over-the-counter market generally have limited trading volume and exhibit a wider spread between the bid/ask quotation, as compared to securities listed on a national securities exchange. Consequently, you may not be able to liquidate your investment in the event of an emergency or for any other reason.

If our common stock is delisted from the Nasdaq, we could face significant material adverse consequences, including:

A limited availability of market quotations for our common stock;

A reduced amount of news and analyst coverage for our company;

A decreased ability to issue additional securities or obtain additional financing in the future;

Reduced liquidity for our stockholders;

Potential loss of confidence by partners and employees; and

Loss of institutional investor interest and fewer business development opportunities.

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Additionally, delisting of our common stock from Nasdaq would constitute an event of default under the March 2025 Note and the March 2026 Note.

This is a best efforts offering, no minimum amount of securities is required to be sold, and we may not raise the amount of capital we believe is required for our business plans.

The placement agent has agreed to use its reasonable best efforts to solicit offers to purchase the securities in this offering. The placement agent has no obligation to buy any of the securities from us or to arrange for the purchase or sale of any specific number or dollar amount of the securities. There is no required minimum number of securities that must be sold as a condition to completion of this offering. Because there is no minimum offering amount required as a condition to the closing of this offering, the actual offering amount, placement agent fees and proceeds to us are not presently determinable and may be substantially less than the maximum amounts set forth above. We may sell fewer than all of the securities offered hereby, which may significantly reduce the amount of proceeds received by us, and investors in this offering will not receive a refund in the event that we do not sell an amount of securities sufficient to support our business plans. Thus, we may not raise the amount of capital we believe is required for our operations in the short-term, and may need to raise additional funds in the short-term, which may not be available or available on terms acceptable to us.

Purchasers who purchase our securities in this offering pursuant to a securities purchase agreement may have rights not available to purchasers who purchase without the benefit of a securities purchase agreement.

In addition to rights and remedies available to all purchasers in this offering under federal securities and state law, the purchasers who enter into a securities purchase agreement will also be able to bring claims of breach of contract against us. The ability to pursue a claim for breach of contract provides those investors with the means to enforce the covenants uniquely available to them under the securities purchase agreement including, but not limited to: (i) timely delivery of securities; (ii) agreement to not enter into variable rate financings for one year from closing, subject to certain exceptions; (iii) agreement to not enter into any financings for 30 days from closing, subject to certain exceptions; and (iv) indemnification for breach of contract.

If you purchase securities in this offering, you will suffer immediate dilution of your investment.

The combined offering price per share (or pre-funded warrant) and accompanying common warrant in this offering is higher than the net tangible book value per share of our common stock. Therefore, if you purchase securities in this offering, you will pay a combined offering price per share (or pre-funded warrant) and accompanying common warrant that substantially exceeds our net tangible book value per share after giving effect to this offering. To the extent outstanding options or warrants are exercised, you will incur further dilution. Our net tangible book deficit as of December 31, 2025 was $38.5 million, or $0.60 per share. After giving effect to: (i) the pro forma adjustments described in the section of this prospectus supplement titled “Dilution;” and (ii) the sale of (a) shares of our common stock and accompanying common warrants to purchase an additional shares of our common stock in this public offering at the combined public offering price of $ per share and (b) pre-funded warrants to purchase shares of our common stock and accompanying common warrants to purchase an additional shares of our common stock in this public offering at the combined public offering price minus $0.01 (excluding, in each case, the shares of common stock to be issued and the proceeds received, if any, from any exercises of the pre-funded warrants, the common warrants, and the placement agent warrants, as applicable), and after deducting placement agent fees and estimated offering expenses payable by us, you will experience immediate dilution of $ per share, representing the difference between our pro forma as adjusted net tangible book value per share as of December 31, 2025 after giving effect to this offering. See the section of this prospectus supplement titled “Dilution” for a more detailed discussion of the dilution you will incur if you purchase securities in this offering.

We have broad discretion over the use of our cash and cash equivalents, including the net proceeds we receive in this offering, and despite our efforts may not use them in a manner that increases the value of your investment.

Our management has broad discretion to use our cash and cash equivalents, including the net proceeds we receive in this offering, to fund our operations and could spend these funds in ways that do not improve our results of operations or enhance the value of our common stock. The failure by our management to apply these funds effectively could result in financial losses that could have an adverse effect on our business, cause the price of our common stock to decline and delay the development of our product candidates.

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There is no public market for the common warrants or the pre-funded warrants being offered by us in this offering.

There is no established public trading market for the common warrants or the pre-funded warrants being sold in this offering, and we do not expect a market to develop. In addition, we do not intend to apply to list the common warrants or the pre-funded warrants on any securities exchange or recognized trading system. Without an active market, the liquidity of the common warrants or the pre-funded warrants will be limited.

The common warrants are speculative in nature. You may not be able to recover your investment in the common warrants, and the common warrants may expire worthless.

The common warrants do not confer any rights of our common stock ownership on their holders, such as voting rights, but rather merely represent the right to acquire shares of our common stock at a fixed price for a limited period of time. Specifically, commencing on the date of issuance, holders of common warrants may exercise their right to acquire the underlying common stock and pay an exercise price per share equal to $ , subject to certain adjustments, and the common warrants will expire five years after the date of issuance. Moreover, following this offering, the market value of the common warrants, if any, is uncertain and there can be no assurance that the market value of the common warrants will equal or exceed their imputed offering price. In addition, there can be no assurance that the market price of our common stock will equal or exceed the exercise price of the common warrants for a sustained period of time or at all, and, consequently, it may not ever be profitable for holders of the common warrants to exercise the common warrants.

Holders of the common warrants or the pre-funded warrants will have no rights as common stockholders until they acquire our common stock.

Until you acquire shares of our common stock upon exercise of the common warrants or the pre-funded warrants, you will have no rights with respect to our common stock issuable upon exercise of the common warrants or the pre-funded warrants, including the right to receive dividend payments, vote or respond to tender offers. Upon exercise of your common warrants or pre-funded warrants, you will be entitled to exercise the rights of a common stockholder only as to matters for which the record date occurs after the exercise date.

Significant holders or beneficial owners of our common stock may not be permitted to exercise the common warrants or the pre-funded warrants that they hold.

A holder of the common warrants or the pre-funded warrants will not be entitled to exercise any portion of any common warrant or pre-funded warrant that, upon giving effect to such exercise, would cause the aggregate number of shares of our common stock beneficially owned by such holder (together with its affiliates) to exceed 4.99% or 9.99%, as applicable, of the number of shares of our common stock outstanding immediately after giving effect to the exercise as such percentage ownership is determined in accordance with the terms of the common warrants or pre-funded warrants and subject to such holder’s rights under the common warrants pre-funded warrants to increase or decrease such percentage to any other percentage not in excess of 9.99% upon at least 61 days’ prior notice from the holder to us. As a result, you may not be able to exercise your pre-funded warrants for shares of our common stock at a time when it would be financially beneficial for you to do so. In such a circumstance, you could seek to sell your pre-funded warrants to realize value, but you may be unable to do so in the absence of an established trading market.

If we do not maintain a current and effective registration statement relating to the shares of our common stock issuable upon exercise of the common warrants or pre-funded warrants at the time that holders wish to exercise such common warrants or pre-funded warrants, they will only be able to exercise them on a “cashless basis” provided that an exemption from registration is available. As a result, the number of shares of our common stock that holders will receive upon exercise of the common warrants or pre-funded warrants will be fewer than it would have been had such holder exercised such common warrants or pre-funded warrants for cash, and holders may be limited in their ability to immediately sell shares upon exercise subject to volume or other securities law limitations. Further, if an exemption from registration is not available, holders would not be able to exercise on a cashless basis and would only be able to exercise their common warrants or pre-funded warrants for cash if a current and effective registration statement relating to the shares of our common stock issuable upon exercise of the common warrants or pre-funded warrants is available.

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USE OF PROCEEDS

We estimate that the net proceeds from the sale of the shares of common stock, pre-funded warrants to purchase shares of common stock and accompanying common warrants that we are offering, excluding the proceeds, if any, from the exercise of the common warrants or the pre-funded warrants offered hereby, will be approximately $ , based on the combined public offering price of $ per share of common stock (or pre-funded warrants at the combined public offering price less $0.01) and accompanying common warrant to purchase shares of common stock, and after deducting placement agent fees and estimated offering expenses payable by us if we sell the maximum amount of securities offered hereby. This estimate excludes the proceeds, if any, from the exercise of the common warrants and the pre-funded warrants sold in this offering. However, because this is a best efforts offering and there is no minimum offering amount required as a condition to the closing of this offering, the actual offering amount, the placement agent fees and net proceeds to us are not presently determinable and may be substantially less than the maximum amounts set forth on the cover page of this prospectus supplement.

We intend to use the net proceeds from this offering, together with our cash and cash equivalents, for working capital and general corporate purposes. These expected uses represent our intentions based upon our current plans and business conditions, which could change in the future as our plans and business conditions evolve. The amounts and timing of these expenditures will depend on numerous factors, including the development of our current business initiatives. We have no specific acquisition contemplated at this time. As of the date of this prospectus supplement, we cannot specify with certainty all of the particular uses for the net proceeds from this offering. Our management has broad discretion to use our cash and cash equivalents, including the net proceeds we receive in this offering, to fund our operations and investors will be relying upon the judgment of our management regarding the application of these proceeds. The failure by our management to apply these funds effectively could harm our business and cause the price of our common stock to decline, perhaps significantly. The amounts and timing of our actual expenditures will depend on numerous factors, including factors described under “Risk Factors” in this prospectus supplement and the documents incorporated by reference herein and therein.

If all of the common warrants sold in this offering were to be exercised in cash at an exercise price per share equal to $ , we would receive additional net proceeds of approximately $ million, after deducting placement agent fees payable by us. We cannot predict when or if the common warrants will be exercised. It is also possible that the common warrants may expire and may never be exercised. We may not sell any pre-funded warrants in this offering. If we sell any pre-funded warrants, we will receive only $0.01 per share upon exercise thereof.

In addition, we may receive proceeds from the exercise of the placement agent warrants, to the extent such placement agent warrants are exercised for cash, but we will not receive any proceeds from any sale of the shares of common stock underlying the placement agent warrants.

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DILUTION

Our net tangible book deficit as of December 31, 2025 was $38.5 million, or $0.60 per share of common stock. Net tangible book value is total assets minus the sum of liabilities and intangible assets. Net tangible book value per share is net tangible book value divided by the total number of shares of our common stock outstanding as of December 31, 2025.

Our pro forma net tangible book deficit as of December 31, 2025 was approximately $29.2 million, or $0.35 per share of common stock. Pro forma net tangible book deficit reflects total tangible assets minus total liabilities, adjusted to give effect to (i) the sale of 5,000,000 shares of our common stock under our Sales Agreement, resulting in approximately $2.4 million of net proceeds, and (ii) the issuance of 15,057,649 shares of common stock upon the conversion of $6.9 million in principal and accrued interest under the March 2025 Note, each occurring subsequent to December 31, 2025.

Dilution in net tangible book value per share represents the difference between the amount per share paid by purchasers of securities in this offering, and the pro forma as adjusted net tangible book value per share of our common stock immediately after completion of this offering.

After giving effect to the issuance and sale of (i) shares of our common stock and accompanying common warrants to purchase an additional shares of our common stock in this public offering at the combined public offering price of $ per share and (ii) pre-funded warrants to purchase shares of our common stock and accompanying common warrants to purchase an additional shares of our common stock in this public offering at the combined public offering price minus $0.01 (excluding, in each case, the shares of common stock to be issued and the proceeds received, if any, from exercises of the pre-funded warrants, the common warrants and the placement agent warrants, as applicable), and after deducting placement agent fees and estimated offering expenses payable by us, our pro forma as adjusted net tangible book value as of December 31, 2025 would have been approximately $ million, or $ per share. This represents an immediate increase in the net tangible book value of $ per share to existing stockholders and immediate dilution in net tangible book value of $ per share to investors purchasing securities in this offering.

The following table illustrates this dilution on a per share basis to new investors participating in this offering:

Combined public offering price per share (or pre-funded warrant) and accompanying common warrant to purchase one share of common stock	$
Historical net tangible book deficit per share as of December 31, 2025	$	(0.60	)
Increase in net tangible book value per share attributable to the pro forma adjustments described above		0.25
Pro forma net tangible book deficit per share as of December 31, 2025		(0.35	)
Increase in net tangible book value per share attributable to this offering
Pro forma as adjusted net tangible book value per share as of December 31, 2025, after giving effect to this offering
Dilution per share to new investors purchasing common stock in this offering	$

Investors who purchase common stock upon the exercise of the common warrants or the pre-funded warrants offered hereby may experience dilution depending on our net tangible book value at the time of exercise.

The above discussion and table are based on 64,556,570 shares of our common stock outstanding as of December 31, 2025. This number excludes shares issuable on exercise of pre-funded warrants and common warrants being sold in this offering and the placement agent warrants, and also excludes the following:

6,670,881 shares of common stock issuable upon exercise of outstanding stock options granted under the 2024 Plan as of December 31, 2025, with a weighted-average exercise price of $6.56 per share;

1,573,065 shares of common stock reserved for future issuance under the 2024 Plan as of December 31, 2025;

47,407 shares of common stock reserved for future issuance under our ESPP as of December 31, 2025, as well as any future automatic annual increases in the number of shares of common stock reserved for issuance under the ESPP;

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35,534,727 shares of common stock issuable upon exercise of outstanding warrants as of December 31, 2025 with a weighted-average exercise price of $3.09 per share;

13,268,156 shares of common stock which may be issuable upon the conversion of the March 2025 Note, which had an outstanding principal balance and accrued interest of $30.0 million as of December 31, 2025 and which had a conversion price of $2.26;

5,000,000 shares of our common stock sold since December 31, 2025 under the Sales Agreement and up to approximately $62.0 million of shares of our common stock remaining to be sold under the Sales Agreement; and

15,057,649 shares of our common stock issued upon the conversion of $6.9 million in principal and accrued interest under the March 2025 Note subsequent to December 31, 2025.

If the holders of the pre-funded warrants and common warrants offered hereby exercise all of the pre-funded warrants and common warrants in full (but without giving effect to the exercise of the placement agent warrants), our pro forma as adjusted net tangible book value per share after this offering would be $ , representing an immediate increase in pro forma as adjusted net tangible book value per share of $ to existing stockholders and immediate dilution in pro forma as adjusted net tangible book value per share of $ to new investors purchasing securities in this offering.

To the extent that outstanding options and warrants are exercised or settle, as applicable, including the placement agent warrants, or other shares are issued, investors purchasing our securities in this offering may experience further dilution. In addition, we will need to raise additional capital, and, to the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to investors in this offering.

We have not yet determined whether the common warrants or the pre-funded warrants will be classified and accounted for as liabilities or as equity.

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DESCRIPTION OF SECURITIES WE ARE OFFERING

We are offering shares of our common stock, pre-funded warrants to purchase shares of our common stock, or the pre-funded warrants, and accompanying warrants to purchase shares of our common stock, or the common warrants. The common stock (or pre-funded warrants) and the common warrants will be sold together. Each share of our common stock (or pre-funded warrant) will be sold with a common warrant to purchase one share of our common stock. The shares of our common stock (or pre-funded warrants) and the accompanying common warrants are immediately separable and will be issued separately. The shares of our common stock issuable from time to time upon exercise of the common warrants and the pre-funded warrants, if any, are also being offered pursuant to this prospectus supplement and the accompanying prospectus.

Description of Common Stock

As of the date of this prospectus supplement, our restated certificate of incorporation authorizes us to issue 260,000,000 shares of common stock, par value $0.01 per share, and 10,000,000 shares of preferred stock, par value $0.01 per share. Shares of our common stock are our only security registered pursuant to Section 12 of the Exchange Act. Each holder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders. The affirmative vote of holders of 66 2∕3% of the voting power of all of the then-outstanding shares of capital stock, voting as a single class, will be required to amend certain provisions of our certificate of incorporation, including provisions relating to amending our bylaws, the classified board, the size of our board, removal of directors, director liability, vacancies on our board, special meetings, stockholder notices, actions by written consent and exclusive jurisdiction.

For more information, see “Description of Capital Stock” in Exhibit 4.1 to our Annual Report on Form 10-K for the year ended September 30, 2025, which Exhibit 4.1 is incorporated by reference into this prospectus supplement and the accompanying prospectus.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Equiniti Trust Company, LLC. Its address is 48 Wall Street, Floor 23, New York, NY 10005.

Listing on Nasdaq

Our common stock is listed on The Nasdaq Capital Market under the symbol “OTLK.”

Common Warrants

The material terms and provisions of the common warrants being issued in this offering are summarized below. The following description is subject to, and qualified in its entirety by, the form of common warrant which will be filed as an exhibit to a Current Report on Form 8-K to be filed by us with the SEC in connection with this offering. You should review the form of common warrant for a complete description of the terms and conditions applicable to the common warrants. See “Where You Can Find More Information” in this prospectus supplement.

General. Each purchaser of a share of our common stock or pre-funded warrant will receive a common warrant to purchase one share of our common stock.

Exercisability. The common warrants will be exercisable on the issuance date and will expire five years from the date of issuance. The common warrants will be exercisable, at the option of each holder, in whole or in part by delivering to us or the warrant agent a duly executed exercise notice and by payment in full in immediately available funds for the number of shares of our common stock purchased upon such exercise. However, if a registration statement registering the issuance of the shares of our common stock underlying a common warrant held by holder under the Securities Act is not effective or available for the issuance of such shares to such holder at the time of exercise, the holder may only exercise the common warrant through a “cashless exercise,” in which case, the holder would receive upon such exercise, the net number of shares of our common stock determined according to the formula set forth in the common warrant. Apart from the limited circumstance where such a registration statement is not then effective or available, the exercise price must be paid by the holder in cash in immediately available funds.

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Exercise Limitations. A holder (together with its affiliates and other attribution parties) may not exercise any portion of a common warrant to the extent that immediately after giving effect to such exercise the holder would own more than 4.99 % (or, upon election of the holder, 9.99%) of our outstanding common stock immediately after exercise, which percentage may be changed at the holder’s election to a higher or lower percentage not in excess of 9.99% upon 61 days’ notice to us subject to the terms of the common warrants.

Exercise Price. The initial per share exercise price of the common warrants is $ . The exercise price and number of shares of our common stock issuable upon exercise is subject to adjustment in the event of stock dividends and distributions, stock splits, stock combinations, reclassifications or similar events affecting our common stock.

Transferability. Subject to compliance with any applicable securities laws, the common warrants are separately tradeable immediately after issuance at the option of the holders and may be transferred at the option of the holders.

No Listing. There is no established public trading market for the common warrants and we do not expect a market to develop. In addition, we do not intend to apply for listing of the common warrants on any securities exchange or recognized trading system, including Nasdaq. Without an active market, the liquidity of the common warrants will be limited.

Fundamental Transactions. In the event of a fundamental transaction, as described in the common warrants and generally including any reorganization, recapitalization or reclassification of our common stock, the sale, transfer or other disposition of all or substantially all of our properties or assets, our consolidation or merger with or into another person, the acquisition of more than 50% of our outstanding common stock, or any person or group becoming the beneficial owner of more than 50% of the voting power represented by our outstanding common stock, the holders of the common warrants will be entitled to receive upon exercise of the common warrants the kind and amount of securities, cash or other property that the holders would have received had they exercised the common warrants immediately prior to such fundamental transaction. Notwithstanding the foregoing, as more fully described in the common warrant, in the event of certain fundamental transactions, the holders of the common warrants will be entitled to receive consideration in an amount equal to the Black Scholes value of the common warrants.

Rights as a Stockholder. Except for the right to participate in certain dividends and distributions and as otherwise provided in the common warrant or by virtue of a holder’s ownership of shares of our common stock, the holders of the common warrants do not have the rights or privileges of holders of our common stock, including any voting rights, until they exercise their common warrants.

Pre-Funded Warrants

The material terms and provisions of the pre-funded warrants being issued in this offering are summarized below. The following description is subject to, and qualified in its entirety by, the form of pre-funded warrant which will be filed as an exhibit to a Current Report on Form 8-K to be filed by us with the SEC in connection with this offering. You should review the form of pre-funded warrant for a complete description of the terms and conditions applicable to the pre-funded warrants. See “Where You Can Find More Information” in this prospectus supplement.

Exercisability. The pre-funded warrants do not expire, will be immediately exercisable, at the option of each holder, in whole or in part, by delivering to us a duly executed exercise notice and by payment in full in immediately available funds for the number of shares of our common stock purchased upon such exercise. As an alternative to payment of the exercise price in immediately available funds, the holder may elect to exercise the pre-funded warrant through a cashless exercise, in which case the holder would receive upon such exercise the net number of shares of our common stock determined according to the formula set forth in the pre-funded warrant.

Exercise Limitations. A holder (together with its affiliates and other attribution parties) may not exercise any portion of a pre-funded warrant to the extent that immediately after giving effect to such exercise the holder would own more than 4.99% (or, upon election of the holder, 9.99%) of our outstanding common stock immediately after exercise, which percentage may be changed at the holder's election to a higher or lower percentage not in excess of 9.99% upon 61 days' notice to us subject to the terms of the pre-funded warrants.

Exercise Price. Each pre-funded warrant offered hereby has an initial exercise price per share equal to $0.01. The pre-funded warrants are immediately exercisable and may be exercised at any time until the pre-funded warrants are exercised in full. The exercise price and number of shares of our common stock issuable upon exercise is subject to adjustment in the event of stock dividends and distributions, stock splits, stock combinations, reclassifications or similar events affecting our common stock.

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Transferability. Subject to compliance with any applicable securities laws, the pre-funded warrants are separately tradeable immediately after issuance at the option of the holders and may be transferred at the option of the holders.

No Listing. There is no established public trading market for the pre-funded warrants and we do not expect a market to develop. In addition, we do not intend to apply for listing of the pre-funded warrants on any securities exchange or recognized trading system, including The Nasdaq Capital Market. Without an active market, the liquidity of the pre-funded warrants will be limited.

Fundamental Transactions. In the event of a fundamental transaction, as described in the pre-funded warrants and generally including any reorganization, recapitalization or reclassification of our common stock, the sale, transfer or other disposition of all or substantially all of our properties or assets, our consolidation or merger with or into another person, the acquisition of more than 50% of our outstanding common stock, or any person or group becoming the beneficial owner of more than 50% of the voting power represented by our outstanding common stock, the pre-funded warrants shall automatically be deemed to be exercised in full in a cashless exercise effective immediately prior to the consummation of such fundamental transaction, without regard to any limitations on exercise contained in the pre-funded warrants.

Rights as a Stockholder. Except for the right to participate in certain dividends and distributions and as otherwise provided in the pre-funded warrant or by virtue of a holder’s ownership of shares of our common stock, the holders of the pre-funded warrants do not have the rights or privileges of holders of our common stock, including any voting rights, until they exercise their pre-funded warrants.

Warrant Agent. We are acting as warrant agent for the pre-funded warrants.

Placement Agent Warrants

In addition, we have agreed to issue to the placement agent (or its designees) the placement agent warrants to purchase a number of shares of common stock equal to 7.0% of the aggregate number of shares of common stock and pre-funded warrants sold in this offering, at an exercise price of $ , which represents 125% of the public offering price per share and accompanying common warrant to be sold in this offering. The placement agent warrants will be exercisable upon issuance. The placement agent warrants will expire five years from the commencement of sales under this offering. The placement agent warrants issued in this offering will otherwise have substantially the same terms as the common warrants.

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PLAN OF DISTRIBUTION

Pursuant to an engagement agreement, dated March 11, 2026, or the engagement agreement, we have engaged H.C. Wainwright & Co., LLC to act as our exclusive placement agent to solicit offers to purchase the securities offered pursuant to this prospectus supplement and accompanying prospectus on a “reasonable best efforts” basis. The engagement agreement does not give rise to any commitment by the placement agent to purchase any of our securities, and the placement agent will have no authority to bind us by virtue of the engagement agreement. The placement agent is not purchasing or selling any of the securities offered by us under this prospectus supplement and accompanying prospectus, nor is it required to arrange for the purchase or sale of any specific number or dollar amount of securities. This is a reasonable best efforts offering, and there is no minimum offering amount required as a condition to the closing of this offering. The placement agent has agreed to use reasonable best efforts to arrange for the sale of the securities by us. Therefore, we may not sell all of the shares of common stock, pre-funded warrants, and common warrants being offered hereby. The terms of this offering are subject to market conditions and negotiations between us, the placement agent and prospective investors. The placement agent does not guarantee that it will be able to raise new capital in any prospective offering. The placement agent may engage sub-agents or selected dealers to assist with the offering.

Investors purchasing securities offered hereby will have the option to execute a securities purchase agreement with us. In addition to rights and remedies available to all purchasers in this offering under federal securities and state law, the purchasers which enter into a securities purchase agreement will also be able to bring claims of breach of contract against us. The ability to pursue a claim for breach of contract is material to larger purchasers in this offering as a means to enforce the following covenants uniquely available to them under the securities purchase agreement: (i) a covenant to not enter into variable rate financings for a period of one year following the closing of the offering, subject to certain exceptions; and (ii) a covenant to not enter into any equity financings for 30 days from closing of the offering, subject to certain exceptions. The nature of the representations, warranties and covenants in the securities purchase agreements shall include:

standard issuer representations and warranties on matters such as organization, qualification, authorization, no conflict, no governmental filings required, current in SEC filings, no litigation, labor or other compliance issues, environmental, intellectual property and title matters and compliance with various laws such as the Foreign Corrupt Practices Act; and

covenants regarding matters such as no integration with other offerings, filing of a Current Report on Form 8-K to disclose entering into these securities purchase agreements, no shareholder rights plans, no material nonpublic information, use of proceeds, indemnification of purchasers, reservation and listing of common stock and no subsequent equity sales the period specified above.

Delivery of the common stock, pre-funded warrants, if any, and common warrants offered hereby is expected to occur on or about , 2026, subject to the satisfaction of certain customary closing conditions.

Fees and Expenses

We have agreed to pay the placement agent a total cash fee equal to 7.0% of the aggregate gross proceeds raised in this offering and a management fee equal to 1.0% of the aggregate gross proceeds raised in this offering. We will also pay the placement agent a non-accountable expense allowance of $10,000 and up to $15,950 for the expenses of its clearing firm and will reimburse the placement agent’s legal fees and expenses in an amount up to $100,000. We estimate the total offering expenses of this offering that will be payable by us, excluding placement agent fees and expenses, will be approximately $ . After deducting placement agent fees and our estimated offering expenses, we expect the net proceeds from this offering to be approximately $ .

The following table shows the per share of common stock (and accompanying common warrant), per pre-funded warrant (and accompanying common warrant) and total cash fees we will pay to the placement agent in connection with the sale of the shares of common stock, the pre-funded warrants and the common warrants pursuant to this prospectus supplement and accompanying prospectus.

	Per Share of Common Stock and Accompanying Common Warrant	Per Pre-Funded Warrant and Accompanying Common Warrant	Total
Combined public offering price
Placement agent fees
Proceeds to us, before expenses

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Placement Agent Warrants

We have agreed to grant placement agent warrants to the placement agent or its designees to purchase a number of shares of common stock equal to 7.0% of the aggregate number of shares of common stock and pre-funded warrants sold to the investors in this offering. The placement agent warrants will have an exercise price of $ per share (which is 125% of the combined public offering price per share of common stock and accompanying common warrant), will be exercisable upon issuance. The placement agent warrants will expire five years from the commencement of sales under this offering. The placement agent warrants issued in this offering will otherwise have substantially the same terms as the common warrants. The placement agent warrants are registered on the registration statement of which this prospectus supplement and accompanying prospectus form a part.

The placement agent warrants provide for customary anti-dilution provisions (for share dividends, splits and recapitalizations and the like) consistent with FINRA Rule 5110. Pursuant to FINRA Rule 5110(e), the placement agent warrants and any shares issuable thereunder shall not be sold, transferred, assigned, pledged, or hypothecated, or be the subject of any hedging, short sale, derivative, put or call transaction that would result in the effective economic disposition of the securities by any person for a period of 180 days immediately following the date of commencement of sales of this offering, except the transfer of any security: (i) by operation of law or by reason of reorganization of the issuer; (ii) to any FINRA member firm participating in the offering and the officers, partners, registered persons or affiliates thereof, if all securities so transferred remain subject to the lock-up restriction set forth above for the remainder of the time period; (iii) if the aggregate amount of our securities held by the Placement Agent persons does not exceed 1% of the securities being offered; (iv) that is beneficially owned on a pro-rata basis by all equity owners of an investment fund, provided that no participating member manages or otherwise directs investments by the fund and the participating members in the aggregate do not own more than 10% of the equity in the fund; (v) the exercise or conversion of any security, if all securities remain subject to the lock-up restriction set forth above for the remainder of the time period; (vi) if we meet the registration requirements of Forms S-3, F-3 or F-10; or (vii) back to us in a transaction exempt from registration under the Securities Act.

Right of First Refusal

We have granted the placement agent (or any affiliate designated by the placement agent) a right of first refusal for a period of six months following the closing of this offering to act as sole book-running manager, sole underwriter or sole placement agent for each and every future public offering (including an at-the-market offering) or private offering or any other capital-raising financing of equity, equity-linked or debt securities by us or any of our successors or subsidiaries, subject to certain exceptions. Notwithstanding anything to the contrary contained in this paragraph, in accordance with FINRA Rule 5110(g)(6)(A)(i), any such right of first refusal described in this paragraph shall not have a duration of more than three years from the commencement of sales of the first offering or the termination date of the term of the engagement agreement.

Tail

We have also agreed to pay the placement agent a tail fee equal to the cash and warrant compensation in this offering with respect to any public or private offering or other financing or capital-raising transaction of any kind (“Tail Financing”) to the extent that any capital or funds in such Tail Financing is provided to the Company directly or indirectly by investors whom the placement agent had contacted during the term of our engagement agreement with the placement agent or introduced to the Company during the term of our engagement agreement with the placement agent, if such Tail Financing is consummated at any time during the 12-month period following the termination or expiration of our engagement agreement with the placement agent.

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Other Relationships

From time to time, the placement agent or its affiliates has provided, or may provide in the future, various advisory, investment and commercial banking and other services to us or our affiliates in the ordinary course of business, for which it has or may receive customary fees and commissions. Except as disclosed in this prospectus supplement, we have no present arrangements with the placement agent for any services.

In addition, in the ordinary course of their business activities, the placement agent and its affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) for their own account and for the accounts of their customers. Such investments and securities activities may involve securities and/or instruments of ours or our affiliates. The placement agent and its affiliates may also make investment recommendations and/or publish or express independent research views in respect of such securities or financial instruments and may hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

Determination of Offering Price

The combined public offering price per share of common stock and accompanying common warrant and the combined public offering price per pre-funded warrant and accompanying common warrant we are offering, and the exercise prices and other terms of the pre-funded warrants and common warrants were negotiated between us and the investors, in consultation with the placement agent based on the trading of our shares of common stock prior to this offering, among other things. Other factors considered in determining the offering prices of the securities we are offering and the exercise prices and other terms of the pre-funded warrants and common warrants include the history and prospects of our company, the stage of development of our business, our business plans for the future and the extent to which they have been implemented, an assessment of our management, general conditions of the securities markets at the time of the offering and such other factors as were deemed relevant.

Lock-Up Agreements

We and each of our officers and directors have agreed with the placement agent to be subject to a lock-up period of 30 days following the date of this prospectus supplement. This means that, during the applicable lock-up period, we may not offer for sale, contract to sell, or sell any shares of our common stock or any securities convertible into, or exercisable or exchangeable for, shares of our common stock subject to certain customary exception such as issuing stock options to directors, officers, employees and consultants under our existing plans. We have agreed not to amend, modify, waive or terminate any provision of any of these lock-up agreements. In addition, we have agreed to not issue any shares of common stock or securities exercisable or convertible into shares of common stock for a period of 30 days following the closing date of this offering, subject to certain exceptions, and to not issue any securities that are subject to a price reset based on trading prices of our common stock or upon a specified or contingent event in the future, or enter into an agreement to issue securities at a future determined price, until the date that is one year following the closing date of the offering.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Equiniti Trust Company, LLC. Its address is 48 Wall Street, Floor 23, New York, NY 10005.

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Nasdaq Listing

Our common stock is listed on The Nasdaq Capital Market under the symbol “OTLK.” There is no established trading market for the pre-funded warrants or the common warrants, and we do not expect a trading market to develop. We do not intend to list the pre-funded warrants or the common warrants on any securities exchange or nationally recognized trading system. Without a trading market, the liquidity of the pre-funded warrants and common warrants will be extremely limited.

Indemnification

We have agreed to indemnify the placement agent against certain liabilities, including liabilities under the Securities Act, or to contribute to payments the placement agent may be required to make with respect to any of these liabilities.

Regulation M

The placement agent may be deemed to be an underwriter within the meaning of Section 2(a)(11) of the Securities Act and any fees received by it and any profit realized on the sale of the securities by it while acting as principal might be deemed to be underwriting discounts or commissions under the Securities Act. The placement agent will be required to comply with the requirements of the Securities Act and the Exchange Act, including, without limitation, Rule 10b- 5 and Regulation M under the Exchange Act. These rules and regulations may limit the timing of purchases and sales of our securities by the placement agent. Under these rules and regulations, the placement agent may not (i) engage in any stabilization activity in connection with our securities; and (ii) bid for or purchase any of our securities or attempt to induce any person to purchase any of our securities, other than as permitted under the Exchange Act, until they have completed their participation in the distribution.

Electronic Offer, Sale and Distribution of Securities

A prospectus supplement and accompanying prospectus in electronic format may be made available on the websites maintained by the placement agent, if any, participating in this offering and the placement agent may distribute prospectuses electronically. Other than the prospectus in electronic format, the information on these websites is not part of this prospectus supplement or accompanying prospectus or the registration statement of which this prospectus supplement and accompanying prospectus form a part, has not been approved or endorsed by us or the placement agent, and should not be relied upon by investors.

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MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES

The following is a general discussion of the material United States, or U.S., federal income tax considerations of the purchase, ownership and disposition of shares of our common stock issued pursuant to this offering, or the Shares, the purchase, exercise, disposition and lapse of warrants to purchase shares of our common stock pursuant to this offering, or the common warrants, the purchase, ownership and disposition of pre-funded warrants to purchase shares of our common stock issued pursuant to this offering, or the pre-funded warrants, and the ownership and disposition of shares of our common stock issuable upon exercise of the common warrants or the pre-funded warrants, or the warrant shares. The Shares, the common warrants, the warrant shares and the pre-funded warrants are collectively referred to herein as our “securities.” All prospective holders of our securities should consult their tax advisors with respect to the U.S. federal, state, local and non-U.S. tax consequences of the purchase, ownership and disposition of our securities.

This discussion is not a complete analysis of all potential U.S. federal income tax consequences relating to the purchase, ownership and disposition of our securities. This discussion is based on current provisions of the U.S. Internal Revenue Code of 1986, as amended, which we refer to as the Code, existing U.S. Treasury Regulations promulgated thereunder, published administrative pronouncements and rulings of the U.S. Internal Revenue Service, which we refer to as the IRS, and judicial decisions, all as in effect as of the date of this prospectus supplement. These authorities are subject to change and to differing interpretation, possibly with retroactive effect. Any change or differing interpretation could alter the tax consequences to holders described in this discussion. There can be no assurance that a court or the IRS will not challenge one or more of the tax consequences described herein, and we have not obtained, nor do we intend to obtain, a ruling with respect to the U.S. federal income tax consequences to a holder of the purchase, ownership or disposition of our securities.

We assume in this discussion that a holder holds our securities as a “capital asset” within the meaning of Section 1221 of the Code (generally, property held for investment). This discussion does not address all aspects of U.S. federal income taxation that may be relevant to a particular holder in light of that holder’s individual circumstances, nor does it address any alternative minimum, Medicare contribution, estate or gift tax consequences, or any aspects of U.S. state, local or non-U.S. taxes or any other U.S. federal tax laws. This discussion also does not address consequences relevant to holders subject to special tax rules, such as holders that own or have owned, or are deemed to own or have owned, more than 5% of our capital stock (except to the extent specifically set forth below), corporations that accumulate earnings to avoid U.S. federal income tax, tax-exempt organizations, governmental organizations, banks, financial institutions, investment funds, insurance companies, brokers, dealers or traders in securities, commodities or currencies, regulated investment companies or real estate investment trusts, persons that have a “functional currency” other than the U.S. dollar, tax-qualified retirement plans, “qualified foreign pension funds” as defined in Section 897(l)(2) of the Code and entities all of the interests of which are held by qualified foreign pension funds, holders who hold or receive our securities pursuant to the exercise of employee stock options or otherwise as compensation, holders holding our securities as part of a hedge, wash, straddle or other risk reduction strategy, conversion transaction or other integrated investment, holders deemed to sell our securities under the constructive sale provisions of the Code, holders subject to special tax accounting rules under Section 451(b) of the Code, controlled foreign corporations, passive foreign investment companies and certain former U.S. citizens or long-term residents.

In addition, this discussion does not address the tax treatment of partnerships (or entities or arrangements that are treated as partnerships or disregarded entities for U.S. federal income tax purposes) or persons that hold our securities through such partnerships. If a partnership, including any entity or arrangement treated as a partnership for U.S. federal income tax purposes, holds our securities, the U.S. federal income tax treatment of a partner in such partnership will generally depend upon the status of the partner and the activities of the partnership. Such partners and partnerships should consult their tax advisors regarding the tax consequences of the purchase, ownership and disposition of our securities.

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Treatment of Pre-Funded Warrants

Although it is not entirely free from doubt, we believe a pre-funded warrant should be treated as a Share for U.S. federal income tax purposes and a holder of pre-funded warrants should generally be taxed in the same manner as a holder of Shares, as described below. Accordingly, no gain or loss should be recognized upon the exercise of a pre-funded warrant and, upon exercise, the holding period of a pre-funded warrant should carry over to the Share received. Similarly, the tax basis of the pre-funded warrant should carry over to the Share received upon exercise, increased by the exercise price of $0.01 per share. However, our characterization is not binding on the IRS, and the IRS may treat the pre-funded warrants as warrants to acquire our Shares. If so, the amount and character of your gain with respect to an investment in our pre-funded warrants could change. Accordingly, each holder should consult his, her or its own tax advisor regarding the risks associated with the acquisition of pre-funded warrants pursuant to this offering (including potential alternative characterizations). The balance of this discussion generally assumes that the characterization described above is respected for U.S. federal income tax purposes.

Allocation of Purchase Price

Each purchaser of Shares or pre-funded warrants must allocate its purchase price for such Shares, or pre-funded warrants between each Share and common warrant and between each pre-funded warrant and common warrant, as applicable, based on the respective relative fair market values of each at the time of issuance. This allocation of the purchase price will establish the holder’s initial tax basis for U.S. federal income tax purposes for each Share, pre-funded warrant and common warrant. A holder’s allocation of the purchase price among the Shares, pre-funded warrants and common warrants is not binding on the IRS or the courts, and no assurance can be given that the IRS or the courts will agree with a holder’s allocation. Each holder should consult its own tax advisor regarding the allocation of the purchase price among the Shares, pre-funded warrants and common warrants.

Tax Considerations Applicable to U.S. Holders

Definition of U.S. Holder

In general, a “U.S. holder” means a beneficial owner of our securities (other than a partnership or an entity or arrangement treated as a partnership for U.S. federal income tax purposes) that is, for U.S. federal income tax purposes:

an individual who is a citizen or resident of the United States;

a corporation, or an entity treated as a corporation for U.S. federal income tax purposes, created or organized in the United States or under the laws of the United States or of any state thereof or the District of Columbia;

an estate, the income of which is subject to U.S. federal income tax regardless of its source; or

a trust if (a) a U.S. court can exercise primary supervision over the trust’s administration and one or more U.S. persons have the authority to control all of the trust’s substantial decisions or (b) the trust has a valid election in effect under applicable U.S. Treasury Regulations to be treated as a U.S. person.

Exercise of Common warrants

A U.S. holder generally will not recognize gain or loss on the exercise of a common warrant and the related receipt of warrant shares (unless cash is received in lieu of the issuance of a fractional warrant share). A U.S. holder’s initial tax basis in a warrant share will be equal to the sum of (a) such U.S. holder’s tax basis in the common warrant plus (b) the exercise price paid by such U.S. holder on the exercise of such common warrant. A U.S. holder’s holding period in a warrant share received on the exercise of a common warrant generally should begin on the day after the date that such common warrant is exercised by such U.S. holder.

In certain circumstances, the common warrants may be exercised on a cashless basis. The U.S. federal income tax treatment of an exercise of a warrant on a cashless basis is not clear, and could differ from the consequences described above. It is possible that a cashless exercise could be a taxable event. U.S. holders are urged to consult their tax advisors as to the consequences of an exercise of a common warrant on a cashless basis, including with respect to their holding period and tax basis in the warrant share.

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Distributions on the Shares or the Warrant Shares

We do not anticipate declaring or paying any future distributions. However, if we do make distributions on the Shares or the warrant shares, such distributions will constitute dividends to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles, and will be includible in your income as ordinary income when received. However, with respect to dividends received by individuals, such dividends are generally taxed at the lower applicable long-term capital gains rates, provided certain holding period and other requirements are satisfied. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a tax-free return of the U.S. holder’s investment, up to such U.S. holder’s adjusted tax basis in the Shares or the warrant shares, as applicable. Any remaining excess will be treated as capital gain from the sale or exchange of such Shares or warrant shares, subject to the tax treatment described in “—Sale or Other Taxable Disposition of the Shares, Pre-Funded Warrants, Common warrants or Warrant Shares.”

Sale or Other Taxable Disposition of the Shares, Pre-Funded Warrants, Common warrants or Warrant Shares

Upon the sale, exchange or other taxable disposition of the Shares, pre-funded warrants (other than by exercise), common warrants (other than by exercise) or warrant shares, a U.S. holder will generally recognize capital gain or loss equal to the difference between the amount of cash and the fair market value of any property received upon the sale, exchange or other taxable disposition and such U.S. holder’s adjusted tax basis in the Shares, pre-funded warrants, common warrants or warrant shares. This capital gain or loss will be long-term capital gain or loss if the U.S. holder’s holding period in such Shares, pre-funded warrants, common warrants or warrant shares is more than one year at the time of the sale, exchange or other taxable disposition. Long-term capital gains recognized by certain non-corporate U.S. holders, including individuals, generally will be subject to reduced rates of U.S. federal income tax. The deductibility of capital losses is subject to certain limitations.

Lapse of Common warrants

Upon the lapse or expiration of a common warrant, a U.S. holder will recognize a loss in an amount equal to such U.S. holder’s tax basis in the common warrant. Any such loss generally will be a capital loss and will be long-term capital loss if the common warrant is held for more than one year. Deductions for capital losses are subject to limitations.

Certain Adjustments to the Pre-Funded Warrants and Common warrants

The terms of each pre-funded warrant and common warrant provide for an adjustment to the number of warrant shares for which the pre-funded warrant or common warrant may be exercised and/or to the exercise price of the pre-funded warrant or common warrant in certain events. An adjustment to the exercise price of a pre-funded warrant or common warrant may be treated as a constructive distribution to a U.S. holder of the pre-funded warrants or common warrants depending on the circumstances of such adjustment if, and to the extent that, such adjustment has the effect of increasing such U.S. holder’s proportionate interest in our “earnings and profits” or assets, depending on the circumstances of such adjustment. In addition, the failure to provide for such an adjustment (or to adequately adjust) may also result in a deemed distribution to U.S. holders of the pre-funded warrants or common warrants or Shares. Any such constructive distribution may be taxable whether or not there is an actual distribution of cash or other property. However, adjustments to the exercise price of pre-funded warrants or common warrants made pursuant to a bona fide reasonable adjustment formula that has the effect of preventing dilution of the interest of the holders thereof generally should not be considered to result in a constructive distribution. Generally, such deemed distributions will be taxable in the same manner as an actual distribution as described in “—Distributions on the Shares or the Warrant Shares,” except that it is unclear whether such deemed distributions would be eligible for the reduced tax rate applicable to certain dividends paid to non-corporate holders or the dividend-received deduction applicable to certain dividends paid to corporate holders. Generally, a U.S. holder’s tax basis in the underlying stock will be increased to the extent any such constructive distribution is treated as a dividend. Proposed U.S. Treasury Regulations address the amount of, timing of, and withholding obligations in respect to, constructive distributions made to holders of convertible securities such as the pre-funded warrants or common warrants. These proposed regulations are effective for constructive distributions made on or after the date of finalization, but may generally be relied upon as to certain matters for constructive distributions that occur prior to such date. U.S. holders should consult their own tax advisors regarding the application of such regulations and other tax considerations relating to the possibility of constructive distributions.

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Backup Withholding and Information Reporting

A U.S. holder may be subject to information reporting and backup withholding when such holder receives payments on our securities (including constructive dividends) or receives proceeds from the sale or other taxable disposition of our securities. Certain U.S. holders are exempt from backup withholding, including C corporations and certain tax-exempt organizations. A U.S. holder will be subject to backup withholding if such holder is not otherwise exempt and such holder:

fails to furnish the holder’s taxpayer identification number, which for an individual is ordinarily his or her social security number;

furnishes an incorrect taxpayer identification number;

is notified by the IRS that the holder previously failed to properly report payments of interest or dividends; or

fails to certify under penalties of perjury that the holder has furnished a correct taxpayer identification number and that the IRS has not notified the holder that the holder is subject to backup withholding.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules may be allowed as a refund or a credit against a U.S. holder’s U.S. federal income tax liability, provided the required information is timely furnished to the IRS. U.S. holders should consult their tax advisors regarding their qualification for an exemption from backup withholding and the procedures for obtaining such an exemption.

Tax Considerations Applicable to Non-U.S. Holders

Definition of non-U.S. Holder

For purposes of this discussion, a “non-U.S. holder” is a beneficial owner of our securities that is neither a U.S. holder nor a partnership or an entity or arrangement treated as a partnership for U.S. federal income tax purposes.

Exercise of Common warrants

A non-U.S. holder generally will not recognize gain or loss on the exercise of a common warrant and the related receipt of warrant shares (unless cash is received in lieu of the issuance of a fractional warrant share and certain other conditions are present, as discussed under “—Gain on Sale, Exchange or Other Taxable Disposition of Our Securities”). See “—Tax Considerations Applicable to U.S. Holders—Exercise of Common warrants.” However, if a cashless exercise of common warrants results in a taxable exchange, as described in “—Tax Considerations Applicable to U.S. Holders—Exercise of Common warrants,” the rules described in “Gain on Sale, Exchange or Other Taxable Disposition of Our Securities” would apply.

Lapse of Common warrants

If a non-U.S. holder allows a common warrant to expire unexercised, such non-U.S. holder will recognize a capital loss in an amount equal to such holder’s tax basis in the common warrant. See “—Tax Considerations Applicable to U.S. Holders—Lapse of Warrants.”

Certain Adjustments to the Pre-Funded Warrants and Common warrants

See the discussion of the rules applicable to constructive distributions on a pre-funded warrant or common warrant in “—Tax Considerations Applicable to U.S. Holders—Certain Adjustments to the Warrants.” If an adjustment to the number of warrant shares that will be issued on the exercise of the Warrants, or an adjustment to the exercise price of the pre-funded warrants or common warrants, results in a constructive distribution, as described in “—Tax Considerations Applicable to U.S. Holders—Certain Adjustments to the Pre-Funded Warrants and Common warrants,” the rules described in “—Distributions on the Shares or the Warrant Shares” would apply. U.S. federal income tax required to be withheld on any portion of such constructive distribution that is treated as a dividend (as described in “—Distributions on the Shares or the Warrant Shares”) may be withheld from warrant shares, sales proceeds subsequently paid or credited, or other amounts payable or distributable to a non-U.S. holder.

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Distributions on the Shares or the Warrant Shares

We do not anticipate declaring or paying any future distributions. However, if we make distributions on the Shares or the warrant shares such distributions will constitute dividends to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a tax-free return of the non-U.S. holder’s investment, up to such non-U.S. holder’s adjusted tax basis in the Shares or the warrant shares, as applicable. Any remaining excess will be treated as capital gain from the sale or exchange of such Shares or warrant shares, subject to the tax treatment described in “—Gain on Sale, Exchange or Other Taxable Disposition of Our Securities” below.

Dividends paid to a non-U.S. holder will generally be subject to withholding of U.S. federal income tax at a 30% rate of the gross amount of the dividend or such lower rate as may be specified by an applicable income tax treaty between the United States and such non-U.S. holder’s country of residence for purposes of such treaty.

Dividends that are treated as effectively connected with a trade or business conducted by a non-U.S. holder within the United States and, if an applicable income tax treaty so provides, that are attributable to a permanent establishment or a fixed base maintained by the non-U.S. holder within the United States, are generally exempt from the 30% withholding tax if the non-U.S. holder satisfies applicable certification and disclosure requirements. However, such U.S. effectively connected income, net of specified deductions and credits, is taxed at the same U.S. federal income tax rates applicable to U.S. persons (as defined in the Code). Any U.S. effectively connected income received by a non-U.S. holder that is a corporation may also, under certain circumstances, be subject to an additional “branch profits tax” at a 30% rate or such lower rate as may be specified by an applicable income tax treaty between the United States and such non-U.S. holder’s country of residence for purposes of such treaty.

To claim a reduction or exemption from withholding, a non-U.S. holder generally will be required to provide (a) a properly executed IRS Form W-8BEN or IRS Form W-8BEN-E (or successor form) and satisfy applicable certification and other requirements to claim the benefit of an applicable income tax treaty between the United States and such non-U.S. holder’s country of residence, or (b) a properly executed IRS Form W-8ECI stating that dividends are not subject to withholding because they are effectively connected with such non-U.S. holder’s conduct of a trade or business within the United States. Non-U.S. holders are urged to consult their tax advisors regarding their entitlement to benefits under a relevant income tax treaty.

A non-U.S. holder that is eligible for a reduced rate of U.S. withholding tax under an income tax treaty may obtain a refund or credit of any excess amounts withheld by timely filing an appropriate claim for refund with the IRS.

Distributions will also be subject to the discussion in “—Backup Withholding and Information Reporting” and “—Foreign Accounts.”

Gain on Sale, Exchange or Other Taxable Disposition of Our Securities

Subject to the discussion in “—Backup Withholding and Information Reporting” and “—Foreign Accounts,” in general, a non-U.S. holder will not be subject to any U.S. federal income tax on any gain realized upon such non-U.S. holder’s sale, exchange or other taxable disposition of our securities unless:

the gain is effectively connected with a U.S. trade or business of the non-U.S. holder and, if an applicable income tax treaty so provides, is attributable to a permanent establishment or a fixed base maintained in the United States by such non-U.S. holder, in which case the non-U.S. holder generally will be taxed at the U.S. federal income tax rates applicable to U.S. persons (as defined in the Code) and, if the non-U.S. holder is a foreign corporation, the branch profits tax described in “—Distributions on the Shares or the Warrant Shares” also may apply;

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the non-U.S. holder is a nonresident alien individual who is present in the United States for 183 days or more in the taxable year of the disposition and certain other conditions are met, in which case the non-U.S. holder will be subject to a 30% U.S. federal income tax (or such lower rate as may be specified by an applicable income tax treaty) on the net gain derived from the disposition, which may be offset by U.S. source capital losses of the non-U.S. holder, if any (even though the individual is not considered a resident of the United States); or

we are, or have been, at any time during the five-year period preceding such disposition (or the non-U.S. holder’s holding period, if shorter) a “U.S. real property holding corporation” in which case such non-U.S. holder generally will be taxed on its net gain derived from the disposition as effectively connected income taxable at the U.S. federal income tax rates applicable to U.S. persons (as defined in the Code); however, the branch profits tax described above will not apply to a U.S. holder that is a foreign corporation. Generally, a corporation is a U.S. real property holding corporation if the fair market value of its U.S. real property interests equals or exceeds 50% of the sum of the fair market value of its worldwide real property interests plus its other assets used or held for use in a trade or business. Although there can be no assurance, we do not believe that we are, or have been, a U.S. real property holding corporation, or that we are likely to become one in the future. Even if we are or become a U.S. real property holding corporation, provided that our common stock is regularly traded, as defined by applicable U.S. Treasury Regulations, on an established securities market, the Shares will be treated as a U.S. real property interest only with respect to a non-U.S. holder that holds more than 5% of our outstanding common stock, directly or indirectly, actually or constructively, during the shorter of the 5-year period ending on the date of the disposition or the period that the non-U.S. holder held the Shares or warrant shares, as applicable. There can be no assurance that our common stock will continue to qualify as regularly traded on an established securities market. Disposition by a non-U.S. holder of common warrants (that are not expected to be regularly traded on an established securities market) may also be eligible for an exemption from withholding even if we are treated as a U.S. real property holding corporation, if on the date such common warrants were acquired by such non-U.S. holder such holdings had a fair market value no greater than the fair market value on that date of 5% of our regularly-traded common stock, provided that, if a non-U.S. holder holding our not-regularly-traded common warrants subsequently acquires additional common warrants, then such interests would be aggregated and valued as of the date of the subsequent acquisition to apply this 5% limitation.

Backup Withholding and Information Reporting

We must report annually to the IRS and to each non-U.S. holder the gross amount of the dividends on our securities paid to such non-U.S. holder and the tax withheld, if any, with respect to such dividends. Non-U.S. holders will have to comply with specific certification procedures to establish that the holder is not a U.S. person (as defined in the Code) in order to avoid backup withholding at the applicable rate with respect to any dividends on our securities. A non-U.S. holder generally will not be subject to U.S. backup withholding with respect to payments of dividends on our securities if it certifies its non-U.S. status by providing a valid IRS Form W-8BEN or IRS Form W-8BEN-E (or successor form) or IRS Form W-8ECI, or otherwise establishes an exemption; provided we do not have actual knowledge or reason to know such non-U.S. holder is a U.S. person, as defined in the Code. Dividends paid to non-U.S. holders subject to the U.S. withholding tax, as described in “—Distributions on the Shares or the Warrant Shares” generally will be exempt from U.S. backup withholding.

Information reporting and backup withholding will generally apply to the proceeds of a disposition of our securities by a non-U.S. holder effected by or through the U.S. office of any broker, U.S. or foreign, unless the holder certifies its status as a non-U.S. holder and satisfies certain other requirements, or otherwise establishes an exemption. Generally, information reporting and backup withholding will not apply to a payment of disposition proceeds to a non-U.S. holder where the transaction is effected outside the United States through a non-U.S. office of a broker. However, for information reporting purposes, dispositions effected through a non-U.S. office of a broker with substantial U.S. ownership or operations generally will be treated in a manner similar to dispositions effected through a U.S. office of a broker. Non-U.S. holders should consult their tax advisors regarding the application of the information reporting and backup withholding rules to them.

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Copies of information returns may be made available to the tax authorities of the country in which the non-U.S. holder resides or is established under the provisions of a specific treaty or agreement.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules from a payment to a non-U.S. holder may be allowed as a credit against the non-U.S. holder’s U.S. federal income tax liability, if any, and may entitle such holder to a refund, provided that the required information is timely furnished to the IRS.

Foreign Accounts

The Code generally imposes a U.S. federal withholding tax of 30% on dividends and, subject to the discussion below regarding proposed regulations issued by the U.S. Treasury Department, the gross proceeds of a disposition of our securities paid to a “foreign financial institution” (as defined in the Code), unless such institution enters into an agreement with the U.S. government to, among other things, withhold on certain payments and to collect and provide to the U.S. tax authorities substantial information regarding accounts held by certain “specific United States persons” or “United States owned foreign entities” (each as defined in the Code), or otherwise qualifies for an exemption from these rules. A U.S. federal withholding tax of 30% also applies to dividends and, subject to the discussion below regarding proposed regulations issued by the U.S. Treasury Department, will apply to the gross proceeds of a disposition of our securities paid to a “non-financial foreign entity” (as defined in the Code), unless such entity provides the withholding agent with either a certification that it does not have any “substantial United States owners” (as defined in the Code), provides information regarding each substantial United States owners of the entity, or otherwise qualifies for an exemption from these rules. Under certain circumstances, a non-U.S. holder might be eligible for refunds or credits of such taxes. An intergovernmental agreement between the United States and an applicable foreign country may modify the requirements described in this paragraph.

The withholding provisions described above currently apply to dividends paid on our securities. The U.S. Treasury Department released proposed regulations which, if finalized in their present form, would eliminate the U.S. federal withholding tax of 30% applicable to the gross proceeds of a sale or other disposition of our securities. In its preamble to such proposed regulations, the U.S. Treasury Department stated that taxpayers may generally rely on the proposed regulations until final regulations are issued.

EACH PROSPECTIVE INVESTOR SHOULD CONSULT ITS TAX ADVISOR REGARDING THE PARTICULAR U.S. FEDERAL, STATE AND LOCAL AND NON-U.S. TAX CONSEQUENCES OF PURCHASING, HOLDING AND DISPOSING OF OUR SECURITIES, INCLUDING THE CONSEQUENCES OF ANY PROPOSED CHANGE IN APPLICABLE LAWS.

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LEGAL MATTERS

The validity of the securities being offered by this prospectus supplement will be passed upon for us by Cooley LLP, Chicago, Illinois. Troutman Pepper Locke LLP, Charlotte, North Carolina, is acting as counsel for the placement agent in connection with this offering.

EXPERTS

The consolidated financial statements of Outlook Therapeutics, Inc. as of September 30, 2025 and 2024, and for each of the years in the two-year period ended September 30, 2025, have been incorporated by reference herein in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing. The audit report covering the September 30, 2025 consolidated financial statements contains an explanatory paragraph that states that the Company has incurred recurring losses and negative cash flows from operations and has an accumulated deficit, that raise substantial doubt about its ability to continue as a going concern. The consolidated financial statements do not include any adjustments that might result from the outcome of that uncertainty.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus supplement and the accompanying prospectus are part of a registration statement on Form S-3 we filed with the SEC under the Securities Act and do not contain all the information set forth or incorporated by reference in the registration statement. Whenever a reference is made in this prospectus supplement or the accompanying prospectus to any of our contracts, agreements or other documents, the reference may not be complete and you should refer to the exhibits that are a part of the registration statement or the exhibits to the reports or other documents incorporated by reference into this prospectus supplement and the accompanying prospectus for a copy of such contract, agreement or other document. Because we are subject to the information and reporting requirements of the Exchange Act, we file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the internet at the SEC’s website at www.sec.gov. Copies of certain information filed by us with the SEC are also available on our website at http://www.outlooktherapeutics.com. Our website is not a part of this prospectus supplement and is not incorporated by reference in this prospectus supplement.

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INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to “incorporate by reference” information from other documents that we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus supplement and the accompanying prospectus. Information in this prospectus supplement supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus supplement, while information that we file later with the SEC will automatically update and supersede the information in this prospectus supplement and the accompanying prospectus. We incorporate by reference the documents listed below and any future filings (other than current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items unless such Form 8-K expressly provides to the contrary) we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus supplement and prior to the termination of the offering of the common stock covered by this prospectus supplement (Commission File No. 001-37759). Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements:

our Annual Report on Form 10-K for the fiscal year ended September 30, 2025, filed with the SEC on December 19, 2025, including the information specifically incorporated by reference therein from our Definitive Proxy Statement on Schedule 14A filed with the SEC on January 26, 2026;

our Quarterly Report on Form 10-Q for the quarter ended December 31, 2025, filed with the SEC on February 17, 2026;

our Current Reports on Form 8-K, filed with the SEC on November 3, 2025, November 13, 2025, January 2, 2026, February 11, 2026, February 18, 2026, March 5, 2026, March 10, 2026, March 11, 2026 and March 16, 2026, to the extent the information in such reports is filed and not furnished;

the description of our common stock set forth in our registration statement on Form 8-A, filed with the SEC on April 29, 2016, as amended on May 11, 2016, including any further amendments thereto or reports filed for the purposes of updating this description, including Exhibit 4.1 of our Annual Report on Form 10-K for the fiscal year ended September 30, 2025, filed with the SEC on December 19, 2025, and including any amendments or reports filed for the purpose of updating such description.

We will furnish without charge to each person, including any beneficial owner, to whom a prospectus is delivered, upon written or oral request, a copy of any or all of the documents incorporated by reference into this prospectus but not delivered with the prospectus, including exhibits that are specifically incorporated by reference into such documents. You should direct any requests for documents to Outlook Therapeutics, Inc., Attention: Corporate Secretary, 111 S. Wood Avenue, Unit #100, Iselin, New Jersey 08830. Our phone number is (609) 619-3990. You may also view the documents that we file with the SEC and incorporate by reference in this prospectus on our corporate website at www.outlooktherapeutics.com. The information on our website is not incorporated by reference and is not a part of this prospectus.

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PROSPECTUS

$300,000,000

Common Stock

Preferred Stock

Debt Securities

Warrants

From time to time, we may offer up to $300,000,000 of any combination of shares of our common stock, shares of our preferred stock, debt securities and warrants to purchase any of such securities, in one or more offerings as described in this prospectus. We may also offer securities as may be issuable upon conversion, redemption, repurchase, exchange or exercise of any securities registered hereunder, including any applicable antidilution provisions.

This prospectus provides a general description of the securities we may offer. Each time we offer securities, we will provide specific terms of the securities offered in a supplement to this prospectus. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings. The prospectus supplement and any related free writing prospectus may also add, update or change information contained in this prospectus. You should carefully read this prospectus, the applicable prospectus supplement and any related free writing prospectus, as well as any documents incorporated by reference, before you invest in any of the securities being offered.

This prospectus may not be used to consummate a sale of securities unless accompanied by a prospectus supplement.

We may sell these securities directly to investors, through agents designated from time to time or to or through underwriters or dealers, on a continuous or delayed basis. For additional information on the methods of sale, you should refer to the section titled “Plan of Distribution” in this prospectus and in the applicable prospectus supplement. If any agents or underwriters are involved in the sale of any securities with respect to which this prospectus is being delivered, the names of such agents or underwriters and any applicable fees, discounts or commissions and over-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.

Our common stock is listed on The Nasdaq Capital Market under the trading symbol “OTLK.” On March 27, 2024, the last reported sale price of our common stock on The Nasdaq Capital Market was $9.37 per share. The applicable prospectus supplement will contain information, where applicable, as to other listings, if any, on The Nasdaq Capital Market or other securities exchange of the securities covered by the applicable prospectus supplement.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading “Risk Factors” on page 7 of this prospectus and any similar section contained in the applicable prospectus supplement and in any related free writing prospectuses we have authorized for use in connection with a specific offering, and under similar headings in the documents that are incorporated by reference into this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is April 5, 2024.

TABLE OF CONTENTS

Page

ABOUT THIS PROSPECTUS	ii
PROSPECTUS SUMMARY	1
THE SECURITIES WE MAY OFFER	4
RISK FACTORS	7
SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS	8
USE OF PROCEEDS	9
DESCRIPTION OF CAPITAL STOCK	10
DESCRIPTION OF DEBT SECURITIES	16
DESCRIPTION OF WARRANTS	23
LEGAL OWNERSHIP OF SECURITIES	25
PLAN OF DISTRIBUTION	28
LEGAL MATTERS	30
EXPERTS	30
WHERE YOU CAN FIND MORE INFORMATION	30
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE	31

ABOUT THIS PROSPECTUS

This prospectus is a part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission, or SEC, utilizing a “shelf” registration process. Under this shelf registration process, we may offer and sell any combination of the securities described in this prospectus in one or more offerings up to a total aggregate offering price of $300,000,000. This prospectus provides you with a general description of the securities we may offer.

Each time we offer and sell securities under this prospectus, we will provide a prospectus supplement that will contain specific information about the terms of that offering. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. The prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change information contained in this prospectus or in any documents that we have incorporated by reference into this prospectus. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement or free writing prospectus, you should rely on the prospectus supplement or free writing prospectus, as applicable. You should read this prospectus, any applicable prospectus supplement and any related free writing prospectus, together with the information incorporated herein by reference as described under the heading “Incorporation of Certain Information by Reference,” before investing in any of the securities offered.

THIS PROSPECTUS MAY NOT BE USED TO CONSUMMATE A SALE OF SECURITIES UNLESS IT IS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.

Neither we, nor any agent, underwriter or dealer has authorized any person to give any information or to make any representation other than those contained or incorporated by reference into this prospectus, any applicable prospectus supplement or any related free writing prospectus prepared by or on behalf of us or to which we have referred you. This prospectus, any applicable supplement to this prospectus or any related free writing prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus, any applicable supplement to this prospectus or any related free writing prospectus constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction.

You should not assume that the information contained in this prospectus, any applicable prospectus supplement or any related free writing prospectus is accurate on any date subsequent to the date set forth on the front of the document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus, any applicable prospectus supplement or any related free writing prospectus is delivered, or securities are sold, on a later date.

This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find More Information.”

This prospectus contains and incorporates by reference market data and industry statistics and forecasts that are based on independent industry publications and other publicly available information. Information that is based on estimates, forecasts, projections, market research, or similar methodologies is inherently subject to uncertainties and involves a number of assumptions and limitations; as a result, actual events or circumstances may differ materially from events and circumstances that are assumed in this information. The industry in which we operate is subject to a high degree of uncertainty and risk due to a variety of factors, including those described under the heading “Risk Factors.” Although we are responsible for all of the disclosure contained in this prospectus and we believe that the data we use from third parties are reliable, we have not separately verified this data. Further, while we believe that our internal research is reliable, such research has not been verified by any third party. You are cautioned not to give undue weight to any such information, projections, and estimates.

Except as otherwise indicated or unless the context otherwise requires, references to “company,” “we,” “us,” “our” or “Outlook Therapeutics,” refer to Outlook Therapeutics, Inc. and its consolidated subsidiaries.

Our name “Outlook Therapeutics,” the Outlook Therapeutics logo and other trademarks or service marks of Outlook Therapeutics, Inc. appearing in this prospectus and in any prospectus supplement or free writing prospectus and the information incorporated by reference herein or therein are the property of Outlook Therapeutics, Inc. Other trademarks, service marks or trade names appearing in this prospectus in any prospectus supplement or free writing prospectus and the information incorporated by reference herein or therein are the property of their respective owners. We do not intend our use or display of other companies’ trade names, trademarks or service marks to imply a relationship with, or endorsement or sponsorship of us by, these other companies.

PROSPECTUS SUMMARY

This summary highlights selected information contained elsewhere in this prospectus or incorporated by reference herein and does not contain all of the information that you need to consider in making your investment decision. You should carefully read the entire prospectus, the applicable prospectus supplement and any related free writing prospectus, including the risks of investing in our securities discussed under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus. You should also carefully read the information incorporated by reference into this prospectus, including our financial statements and related notes, and the exhibits to the registration statement of which this prospectus is a part, before making your investment decision.

Overview

We are a biopharmaceutical company working to launch the first ophthalmic formulation of bevacizumab approved by the U.S. Food and Drug Administration, or the FDA, for use in retinal indications. Our goal is to launch directly in the United States as the first and only approved ophthalmic bevacizumab for the treatment of wet age-related macular degeneration, or wet AMD, diabetic macular edema, or DME, and branch retinal vein occlusion, or BRVO. Our plans also include seeking approval and launching the product in the United Kingdom, Europe, Japan and other markets, either directly into those markets or through a strategic partner. If approved, we expect to receive 12 years of regulatory exclusivity in the United States and up to 10 years of market exclusivity in the European Union.

Bevacizumab is a full-length, humanized anti-VEGF (Vascular Endothelial Growth Factor) recombinant monoclonal antibody, or mAb, that inhibits VEGF and associated angiogenic activity. In March 2022, we submitted a BLA with the FDA for ONS-5010 (LYTENAVA (bevacizumab-vikg)), an investigational ophthalmic formulation of bevacizumab, which we have developed to be administered as an intravitreal injection for the treatment of wet AMD and other retinal diseases. In May 2022, we voluntarily withdrew our BLA to provide additional information requested by the FDA. We re-submitted the BLA to the FDA for ONS-5010 on August 30, 2022, and in October 2022, we received confirmation from the FDA that our BLA had been accepted for filing with a Prescription Drug User Fee Act, or PDUFA, date of August 29, 2023 for a review decision by the FDA. On August 29, 2023, we received a Complete Response Letter, or CRL, in which the FDA concluded it could not approve our BLA during this review cycle due to several chemical, manufacturing and control, or CMC, issues, open observations from pre-approval manufacturing inspections, and a lack of substantial evidence. At subsequent Type A meetings with the FDA, we learned that the FDA was also requiring the successful completion of an additional adequate and well-controlled clinical trial evaluating ONS-5010, as well as additional requested CMC data indicated in the CRL to approve ONS-5010 for use in wet AMD.

We agreed to conduct an additional adequate, and well-controlled clinical trial following discussions with the FDA in support of our BLA for ONS-5010. In December 2023, we submitted a Special Protocol Assessment, or SPA, to the FDA for this study (NORSE EIGHT) seeking confirmation that, if successful, it will address the FDA’s requirement for a second adequate and well-controlled clinical trial to support our planned resubmission of the ONS-5010 BLA. In January 2024, we received confirmation that the FDA has reviewed and agreed upon the NORSE EIGHT trial protocol pursuant to the SPA. If the NORSE EIGHT trial is successful, it would satisfy the FDA’s requirement for a second adequate and well-controlled clinical trial to address fully the clinical deficiency identified in the CRL. The first subject was enrolled in NORSE EIGHT in January 2024. In addition, through a Type A meeting and additional interactions, we have identified the approaches needed to resolve the CMC comments in the CRL. We are working to address the open items and expect to resolve these comments prior to the expected completion of NORSE EIGHT.

Separately, in October 2022 we submitted a Marketing Authorization Application, or MAA, for ONS-5010 with the European Medicines Agency, or the EMA. On December 22, 2022, our MAA was validated for review by the EMA. The MAA was submitted as a ‘full-mixed marketing authorisation application’ based on Article 8.3 of Directive 2001/83/EC. The formal review process of the MAA by the EMA’s Committee for Medicinal Products for Human Use, or CHMP, is now underway with an estimated decision date expected in the first half of calendar year 2024. ONS-5010 is our sole product candidate in active development.

Our initial BLA submission for ONS-5010 in wet AMD involved three clinical trials, which we refer to as NORSE ONE, NORSE TWO and NORSE THREE. The study design for our clinical program to evaluate ONS-5010 as an ophthalmic formulation of bevacizumab was reviewed at an end of Phase 2 meeting with the FDA in April 2018, and we filed our investigational new drug application, or IND, with the FDA in the first quarter of calendar 2019. In August 2020, we reported achieving the anticipated safety and efficacy and positive proof-of-concept topline results from NORSE ONE, a clinical experience study. NORSE TWO is our pivotal Phase 3 clinical trial comparing ONS-5010 (bevacizumab-vikg) to ranibizumab (LUCENTIS). The topline results reported from NORSE TWO in August 2021 showed that ONS-5010 met the primary and key secondary endpoint for efficacy with clinically impactful change observed for treated patients. The NORSE TWO primary endpoint difference in proportion of subjects gaining at least 15 letters in Best Corrected Visual Acuity, or BCVA, score was met and was both highly statistically significant and clinically relevant. In the intent to treat, or ITT, primary dataset, the percentage of patients who gained at least 15 letters who were treated with ONS-5010, was 41.7%, and the percentage of patients who gained at least 15 letters who were treated with ranibizumab was 23.1% (p = 0.0052). The primary endpoint was also statistically significant and clinically relevant in the secondary per protocol, or PP, dataset (p = 0.04) where the percentages were almost identical, at 41.0% with ONS-5010, and 24.7% with ranibizumab. The key secondary endpoint BCVA score change from baseline to month 11 in the primary ITT dataset was also highly statistically significant and clinically relevant (p = 0.0035). A mean change of 11.2 letters in BCVA score was observed with ONS-5010, and with ranibizumab the mean change was 5.8 letters. The results were also statistically significant in the secondary PP dataset (p = 0.01) with a mean change with ONS-5010 of 11.1 letters versus 7.0 letters with ranibizumab. Additionally, the majority of ONS-5010 subjects maintained or gained BCVA during the study (defined as change from baseline in BCVA ≥ 0), with at least 80% of ONS-5010 subjects maintaining BCVA each month. Results were also positive for the remaining NORSE TWO secondary endpoints with 56.5% (p = 0.0016) of ONS-5010 subjects gaining ≥ 10 letters of vision and 68.5% (p = 0.0116) of ONS-5010 subjects gaining ≥ 5 letters of vision. NORSE THREE is an open-label safety study we conducted to ensure the adequate number of safety exposures to ONS-5010 were available for the initial ONS-5010 BLA submission with the FDA. In March 2021, we reported that the results from NORSE THREE showed a positive safety profile for ONS-5010. The NORSE BLA registration program is also being used to support our MAA submission in the European Union.

As we agreed with the FDA in the SPA, NORSE EIGHT will be a randomized, controlled, parallel-group, masked, non-inferiority study of approximately 400 newly diagnosed, wet AMD subjects randomized in a 1:1 ratio to receive 1.25 mg ONS-5010 or 0.5 mg ranibizumab intravitreal injections. Subjects will receive injections at Day 0 (randomization), Week 4, and Week 8 visits. The primary endpoint will be mean change in BCVA from baseline to week 8. The first subject was enrolled in NORSE EIGHT in January 2024. We expect NORSE EIGHT topline results and potential resubmission of the ONS-5010 BLA by the end of calendar year 2024.

Additionally, in November 2021, we began enrolling patients in our NORSE SEVEN clinical trial. The study compares the safety of ophthalmic bevacizumab in vials versus pre-filled syringes in subjects diagnosed with a retinal condition that would benefit from treatment with intravitreal injection of bevacizumab, including exudative age-related macular degeneration, DME, or BRVO. Subjects will be treated for three months, and the enrollment of subjects in the arm of the study receiving ONS-5010 in vials has been completed.

We have also received agreement from the FDA on three Special Protocol Assessments, or SPAs, for three additional registration clinical trials for our ongoing Phase 3 program for ONS-5010. The agreements reached with the FDA on these SPAs cover the protocols for NORSE FOUR, a registration clinical trial evaluating ONS-5010 to treat BRVO, and NORSE FIVE and NORSE SIX, two registration clinical trials evaluating ONS-5010 to treat DME. We intend to initiate these studies following the anticipated FDA approval of our BLA for wet AMD.

Because there are no approved bevacizumab products for the treatment of retinal diseases in the United States and other major global markets, we submitted a standard BLA, and are not using the biosimilar drug development pathway that would be required if Avastin were an approved drug for the targeted diseases. If approved, we believe ONS-5010 has potential to mitigate risks associated with off-label use of unapproved bevacizumab. In the United States, approximately 66.3% of new patient starts are off-label repackaged bevacizumab (ASRS 2022 Membership Survey Presented at ASRS NY 2022).

Risks Associated with our Business

Our business is subject to numerous risks, as described under the heading “Risk Factors” contained in the applicable prospectus supplement and in any free writing prospectuses we have authorized for use in connection with a specific offering, and under similar headings in the documents that are incorporated by reference into this prospectus.

Implications of Being a Smaller Reporting Company

We are a “smaller reporting company” as defined in the Securities Exchange Act of 1934, as amended, or the Exchange Act. As a smaller reporting company, we are eligible to take advantage of certain exemptions from disclosure requirements, including not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act and reduced disclosure obligations regarding executive compensation. We will be able to take advantage of the scaled disclosures available to smaller reporting companies for so long as our voting and non-voting common stock held by non-affiliates is less than $250.0 million measured on the last business day of our second fiscal quarter, or our annual revenue is less than $100.0 million during the most recently completed fiscal year and our voting and non-voting common stock held by non-affiliates is less than $700.0 million measured on the last business day of our second fiscal quarter.

Company Information

We initially incorporated in January 2010 in New Jersey as Oncobiologics, Inc., and in October 2015, we reincorporated in Delaware by merging with and into a Delaware corporation. In November 2018, we changed our name to Outlook Therapeutics, Inc. Our headquarters are located at 485 Route 1 South, Building F, Suite 320, Iselin, New Jersey 08830, and our telephone number at that location is (609) 619-3990. Our website address is www.outlooktherapeutics.com. The information contained on, or that can be accessed through, our website is not part of, and is not incorporated by reference into this prospectus.

THE SECURITIES WE MAY OFFER

We may offer shares of our common stock and preferred stock, various series of debt securities and/or warrants to purchase any of such securities, either individually or in combination, up to a total aggregate offering price of $300,000,000 from time to time in one or more offerings under this prospectus, together with the applicable prospectus supplement and any related free writing prospectus, at prices and on terms to be determined by market conditions at the time of the relevant offering. We may also offer common stock, preferred stock and/or debt securities upon the exercise of warrants. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities under this prospectus, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

designation or classification;

aggregate principal amount or aggregate offering price;

maturity;

original issue discount;

rates and times of payment of interest or dividends;

redemption, conversion, exercise, exchange or sinking fund terms;

restrictive covenants;

voting or other rights;

conversion or exchange prices or rates and, if applicable, any provisions for changes to or adjustments in the conversion or exchange prices or rates and in the securities or other property receivable upon conversion or exchange;

ranking;

restrictive covenants;

voting or other rights; and

a discussion of material or special U.S. federal income tax considerations.

The applicable prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change any of the information contained in this prospectus or in the documents we have incorporated by reference. However, no prospectus supplement or free writing prospectus will offer a security that is not registered and described in this prospectus at the time of the effectiveness of the registration statement of which this prospectus is a part.

This prospectus may not be used to consummate a sale of securities unless it is accompanied by a prospectus supplement.

We may sell the securities directly to investors or to or through agents, underwriters, or dealers. We, and our agents, underwriters or dealers reserve the right to accept or reject all or part of any proposed purchase of securities. If we do offer securities to or through agents, underwriters or dealers, we will include in the applicable prospectus supplement:

the names of those agents, underwriters or dealers;

applicable fees, discounts and commissions to be paid to them;

details regarding over-allotment or other options, if any; and

the net proceeds to us.

Common Stock

We may issue shares of our common stock from time to time. Holders of our common stock are entitled to one vote per share for the election of directors and on all other matters that require stockholder approval. Subject to any preferential rights of any then outstanding preferred stock, in the event of our liquidation, dissolution or winding up, holders of our common stock are entitled to share ratably in the assets remaining after payment of liabilities and the liquidation preferences of any then outstanding preferred stock. Our common stock does not carry any preemptive rights enabling a holder to subscribe for, or receive shares of, our common stock or any other securities convertible into shares of common stock, or any redemption rights.

Preferred Stock

We may issue shares of our preferred stock from time to time, in one or more series. Under our amended and restated certificate of incorporation, our board of directors has the authority, without further action by the stockholders, to issue up to 10,000,000 shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, to fix the rights, preferences and privileges of the shares of each wholly unissued series and any qualifications, limitations or restrictions thereon and to increase or decrease the number of shares of any such series, but not below the number of shares of such series then outstanding.

If we sell any series of preferred stock under this prospectus, we will fix the designations, voting powers, preferences and rights of such series of preferred stock, as well as the qualifications, limitations or restrictions thereof, in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that describes the terms of the series of preferred stock that we are offering before the issuance of the related series of preferred stock. We urge you to read the applicable prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) related to the series of preferred stock being offered, as well as the complete certificate of designation that contains the terms of the applicable series of preferred stock.

Debt Securities

We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. The senior debt securities will rank equally with any other unsecured and unsubordinated debt. The subordinated debt securities will be subordinate and junior in right of payment, to the extent and in the manner described in the instrument governing the debt, to all of our senior indebtedness. Convertible debt securities will be convertible into or exchangeable for our common stock or other securities. Conversion may be mandatory or at the holder’s option and would be at prescribed conversion rates.

Any debt securities issued under this prospectus will be issued under one or more documents called indentures, which are contracts between us and a national banking association or other eligible party, as trustee. In this prospectus, we have summarized certain general features of the debt securities. We urge you, however, to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the series of debt securities being offered, as well as the complete indentures that contain the terms of the debt securities. We have filed the form of indenture as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

Warrants

We may issue warrants for the purchase of common stock, preferred stock and/or debt securities in one or more series. We may issue warrants independently or together with common stock, preferred stock and/or debt securities, and the warrants may be attached to or separate from these securities. In this prospectus, we have summarized certain general features of the warrants. We urge you, however, to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the particular series of warrants being offered, as well as the complete warrant agreements and warrant certificates that contain the terms of the warrants. Forms of the warrant agreements and forms of warrant certificates containing the terms of the warrants being offered have been filed as exhibits to the registration statement of which this prospectus is a part, and supplemental warrant agreements and forms of warrant certificates will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

We will evidence each series of warrants by warrant certificates that we will issue. Warrants may be issued under an applicable warrant agreement that we enter into with a warrant agent. We will indicate the name and address of the warrant agent, if applicable, in the prospectus supplement relating to the particular series of warrants being offered.

RISK FACTORS

Investing in our securities involves a high degree of risk. You should carefully review the risks and uncertainties described under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in our Annual Report on Form 10-K for the fiscal year ended September 30, 2023, as updated by our subsequent annual, quarterly and other reports and documents that are incorporated by reference into this prospectus and the applicable prospectus supplement, before deciding whether to purchase any of the securities being registered pursuant to the registration statement of which this prospectus is a part. Each of the risk factors could adversely affect our business, operating results and financial condition, as well as adversely affect the value of an investment in our securities, and the occurrence of any of these risks might cause you to lose all or part of your investment. Additional risks not presently known to us or that we currently believe are immaterial may also significantly impair our business operations. Please also read carefully the section below titled “Special Note Regarding Forward-Looking Statements.”

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, including the documents that we incorporate by reference herein, contains, and any applicable prospectus supplement or free writing prospectus including the documents we incorporate by reference therein may contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Exchange Act, about us and our industry that involve substantial risks and uncertainties. All statements, other than statements of historical facts contained in this prospectus, including statements regarding our future financial condition, business strategy and plans, and objectives of management for future operations, are forward-looking statements. In some cases you can identify these statements by forward-looking words such as “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potentially,” “seek,” “should,” “will,” “would,” or the negative of these terms or similar expressions. These forward-looking statements include, but are not limited to, statements concerning the following:

the initiation, timing, progress and results of our clinical trials of our lead product candidate, ONS-5010;

our reliance on our contract manufacturing organizations and other vendors;

whether the results of our clinical trials will be sufficient to support domestic or global regulatory approvals;

our ability to obtain and maintain regulatory approval for ONS-5010 in the United States and other markets;

our expectations regarding the potential market size and the size of the patient populations for our product candidates,

if approved, for commercial use;

our ability to fund our working capital requirements;

the rate and degree of market acceptance of our current and future product candidates, including our commercialization

strategy and manufacturing capabilities for ONS-5010;

the implementation of our business model and strategic plans for our business and product candidates;

developments or disputes concerning our intellectual property or other proprietary rights;

our ability to maintain and establish collaborations or obtain additional funding;

our expectations regarding government and third-party payor coverage and reimbursement;

our ability to compete in the markets we serve;

the factors that may impact our financial results; and

our expectations and estimates regarding the sufficiency of our cash resources and our need for additional funding.

These statements reflect our current views with respect to future events and are based on assumptions and are subject to risks and uncertainties. Given these uncertainties, you should not place undue reliance on these forward-looking statements. We discuss in greater detail many of these risks under the heading “Risk Factors” contained in the applicable prospectus supplement, in any free writing prospectuses we may authorize for use in connection with a specific offering, and in our most recent Annual Report on Form 10-K and in our most recent Quarterly Report on Form 10-Q, which are incorporated by reference into this prospectus in their entirety, as well as any amendments thereto reflected in subsequent filings with the SEC. These risks are not exhaustive. Additional factors could harm our business and financial performance, such as risks associated with the current macroeconomic environment, including as a result of the impacts of inflation, high interest rates, current or potential future bank failures or ongoing overseas conflict. Moreover, we operate in a very competitive and rapidly changing environment. New risk factors emerge from time to time, and it is not possible for our management to predict all risk factors, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in, or implied by, any forward-looking statements.

Forward-looking statements represent our estimates and assumptions only as of the date of the document containing the applicable statement. Unless required by law, we undertake no obligation to update or revise any forward-looking statements to reflect new information or future events or developments. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in such forward-looking statements. You should read this prospectus, any applicable prospectus supplement, together with the documents we have filed with the SEC that are incorporated by reference and any free writing prospectus that we may authorize for use in connection with this offering completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements in the foregoing documents by these cautionary statements.

USE OF PROCEEDS

Except as described in any applicable prospectus supplement or in any free writing prospectuses we have authorized for use in connection with a specific offering, we currently intend to use the net proceeds from the sale of the securities offered by us hereunder, if any, for working capital, capital expenditures and general corporate purposes, which may include, among other things, funding research and development, clinical trials, vendor payables, potential regulatory submissions, hiring additional personnel and capital expenditures. We may also use a portion of the net proceeds to in-license, acquire, or invest in additional businesses, technologies, products, or assets, though we currently have no specific agreements, commitments, or understandings with respect to any in-licensing or acquisitions.

The amounts and timing of our use of the net proceeds from this offering will depend on a number of factors, such as the timing and progress of our research and development efforts, the timing and progress of any partnering and commercialization efforts, technological advances and the competitive environment for our products. As of the date of this prospectus, we cannot specify with certainty all of the particular uses for the net proceeds to us from the sale of the securities offered by us hereunder. Accordingly, our management will have broad discretion in the timing and application of these proceeds. Pending application of the net proceeds as described above, we intend to temporarily invest the proceeds in short-term, interest-bearing instruments.

DESCRIPTION OF CAPITAL STOCK

As of the date of this prospectus, our authorized capital stock consists of 60,000,000 shares of common stock, par value $0.01 per share, and 10,000,000 shares of preferred stock, par value $0.01 per share.

The following summary description of our capital stock is based on the provisions of our restated certificate of incorporation, or our Certificate of Incorporation, our second amended and restated bylaws, or our Bylaws, and the applicable provisions of the Delaware General Corporation Law, or DGCL. This information may not be complete in all respects and is qualified entirely by reference to the provisions of our Certificate of Incorporation, our Bylaws and the DGCL. For information on how to obtain copies of our Certificate of Incorporation and our Bylaws, see “Where You Can Find More Information.”

Common Stock

As of March 22, 2024, we had 21,584,256 shares of common stock outstanding, which amount gives effect to a 1-for-20 reverse stock split of our common stock effected on March 14, 2024 and a private placement of shares of our common stock and accompanying warrants to purchase common stock that closed on March 18, 2024.

Voting Rights

Each holder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders. The affirmative vote of holders of 66⅔% of the voting power of all of the then-outstanding shares of capital stock, voting as a single class, will be required to amend certain provisions of our Certificate of Incorporation, including provisions relating to amending our Bylaws, the classified board, the size of our board, removal of directors, director liability, vacancies on our board, special meetings, stockholder notices, actions by written consent and exclusive jurisdiction.

Dividends

Subject to preferences that may apply to any outstanding preferred stock, holders of our common stock are entitled to receive ratably any dividends that our board of directors may declare out of funds legally available for that purpose on a non-cumulative basis.

Liquidation

In the event of our liquidation, dissolution or winding up, holders of our common stock are entitled to share ratably in all assets remaining after payment of liabilities and the liquidation preference of any outstanding preferred stock.

Rights and Preferences

Holders of our common stock have no preemptive, conversion, subscription or other rights, and there are no redemption or sinking fund provisions applicable to our common stock. The rights, preferences and privileges of the holders of our common stock are subject to and may be adversely affected by the rights of the holders of shares of any series of our preferred stock that we may designate in the future.

Common Stock Equivalents

As of March 22, 2024, we had issued and outstanding 124 performance stock unit awards and 2,628,610 stock option awards under our equity incentive plans. At such date, we also had outstanding warrants to acquire an aggregate of 13,136,193 shares of our common stock, including the Private Placement Warrants (as defined below).

Private Placement Warrants

On March 18, 2024, in connection with a private placement, we issued warrants to purchase an aggregate of 12,857,133 shares of our common stock, or the Private Placement Warrants. The Private Placement Warrants have a per share exercise price equal to $7.70, subject to proportional adjustments in the event of stock splits or combinations or similar events. The Private Placement Warrants are exercisable only for cash, except in limited circumstances, at any time after the date of issuance, or the Issue Date, and will expire on March 18, 2029. A holder of Private Placement Warrants may not exercise the Private Placement Warrant if the holder, together with its affiliates, would beneficially own more than a specified percentage of the outstanding common stock (4.99%, 9.99% or 19.99%, as applicable), immediately after giving effect to such exercise, which may be increased or decreased at the holders’ option (not to exceed 19.99%), effective 61 days after written notice to us.

In addition, we may require the holders to cash exercise the Private Placement Warrants under certain circumstances as follows: (i) if the volume-weighted average price of our common stock equals or exceeds $20.00 per share (subject to adjustment in the event of stock splits, combinations or similar events) for 30 consecutive days, or the Stock Price Condition, at any time after we publicly announces topline data from our NORSE EIGHT clinical trial evidencing satisfaction of the trial’s primary endpoints, or the NORSE EIGHT Announcement, upon the consent of a majority of the members of our board of directors, we may require the holders to exercise up to 20% of the aggregate number of Private Placement Warrants issued to such holder on the Issue Date; and (ii) we may require up to the remainder of the Private Placement Warrants be exercised (A) if the Stock Price Condition is satisfied at any time after we publicly announce approval from the FDA of the BLA for ONS-5010, upon the consent of a majority of the members of our board of directors or (B) if the Stock Price Condition is satisfied at any time after the NORSE EIGHT Announcement, upon the unanimous consent of the members of our board of directors present at duly called meeting.

Preferred Stock

Our board of directors has the authority, without further action by our stockholders, to issue up to 10,000,000 shares of preferred stock in one or more series and to fix the number, rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences and sinking fund terms, and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common stock. The issuance of our preferred stock could adversely affect the voting power of holders of common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change in control or other corporate action. Our board of directors has previously designated 1,000,000 shares as “Series A Convertible Preferred Stock,” 200,000 shares as “Series A-1 Convertible Preferred Stock” and 1,500,000 shares as “Series B Convertible Preferred Stock.” As of March 22, 2024, we did not have any shares of preferred stock issued and outstanding.

We will incorporate by reference as an exhibit to the registration statement, which includes this prospectus, the form of any certificate of designation that describes the terms of the series of preferred stock we are offering. This description and the applicable prospectus supplement will include:

the title and stated value;

the number of shares authorized;

the liquidation preference per share;

the purchase price;

the dividend rate, period and payment date, and method of calculation for dividends;

whether dividends will be cumulative or non-cumulative and, if cumulative, the date from which dividends will accumulate;

the procedures for any auction and remarketing, if any;

the provisions for a sinking fund, if any;

the provisions for redemption or repurchase, if applicable, and any restrictions on our ability to exercise those redemption and repurchase rights;

any listing of the preferred stock on any securities exchange or market;

whether the preferred stock will be convertible into our common stock, and, if applicable, the conversion price, or how it will be calculated, and the conversion period;

whether the preferred stock will be exchangeable into debt securities, and, if applicable, the exchange price, or how it will be calculated, and the exchange period;

voting rights, if any, of the preferred stock;

preemptive rights, if any;

restrictions on transfer, sale or other assignment, if any;

whether interests in the preferred stock will be represented by depositary shares;

a discussion of any material U.S. federal income tax considerations applicable to the preferred stock;

the relative ranking and preferences of the preferred stock as to dividend rights and rights if we liquidate, dissolve or wind up our affairs;

any limitations on issuance of any class or series of preferred stock ranking senior to or on a parity with the series of preferred stock as to dividend rights and rights if we liquidate, dissolve or wind up our affairs; and

any other specific terms, preferences, rights or limitations of, or restrictions on, the preferred stock.

When we issue shares of preferred stock under this prospectus, the shares will fully be paid and nonassessable and will not have, or be subject to, any preemptive or similar rights.

Stockholder Registration Rights

Certain holders of our securities, including certain holders of 5% of our capital stock, and certain of our directors are entitled to certain rights with respect to registration of such securities under the Securities Act. These securities are referred to as registrable securities. The holders of these registrable securities possess registration rights pursuant to the terms of registration rights agreements.

In general, the registration of shares of our common stock pursuant to the exercise of registration rights enables the holders to trade such shares without restriction under the Securities Act when the applicable registration statement is declared effective. We generally have agreed to pay the registration expenses for such registration statements, other than underwriting discounts, selling commissions and stock transfer taxes, of the shares registered.

Generally, in an underwritten offering, the managing underwriter, if any, has the right, subject to specified conditions, to limit the number of shares the holders may include. We must use commercially reasonable efforts to keep the registration statement effective until the earlier of the date on which all registrable securities covered by such registration statement have been sold, or at such time that the holders of the registrable securities can sell their shares under Rule 144 of the Securities Act during any three-month period.

Anti-Takeover Provisions of Delaware Law and Our Charter Documents

Section 203 of the DGCL

We are subject to Section 203 of the DGCL, which prohibits a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years after the date that such stockholder became an interested stockholder, with the following exceptions:

before such date, the board of directors of the corporation approved either the business combination or the transaction that resulted in the stockholder becoming an interested stockholder;

upon completion of the transaction that resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction began, excluding for purposes of determining the voting stock outstanding (but not the outstanding voting stock owned by the interested stockholder) those shares owned (1) by persons who are directors and also officers and (2) employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; and

on or after such date, the business combination is approved by the board of directors and authorized at an annual or special meeting of the stockholders, and not by written consent, by the affirmative vote of at least 66⅔% of the outstanding voting stock that is not owned by the interested stockholder.

In general, Section 203 defines a “business combination” to include the following:

any merger or consolidation involving the corporation and the interested stockholder;

any sale, transfer, pledge or other disposition of 10% or more of the assets of the corporation involving the interested stockholder;

subject to certain exceptions, any transaction that results in the issuance or transfer by the corporation of any stock of the corporation to the interested stockholder;

any transaction involving the corporation that has the effect of increasing the proportionate share of the stock or any class or series of the corporation beneficially owned by the interested stockholder;

the receipt by the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other financial benefits by or through the corporation; and

in general, Section 203 defines an “interested stockholder” as an entity or person who, together with the person’s affiliates and associates, beneficially owns, or within three years prior to the time of determination of interested stockholder status did own, 15% or more of the outstanding voting stock of the corporation.

The statute could prohibit or delay mergers or other takeover or change in control attempts and, accordingly, may discourage attempts to acquire us even though such a transaction may offer our stockholders the opportunity to sell their stock at a price above the prevailing market price.

Certificate of Incorporation and Bylaws

Among other things, our Certificate of Incorporation and Bylaws:

permit our board of directors to issue up to 10,000,000 shares of preferred stock, with any rights, preferences and privileges as they may designate, including the right to approve an acquisition or other change in control;

provide that the authorized number of directors may be changed only by resolution of our board of directors;

provide that our board of directors is classified into three classes of directors;

provide that, subject to the rights of any series of preferred stock to elect directors, directors may only be removed for cause, which removal may be effected, subject to any limitation imposed by law, by the holders of at least a majority of the voting power of all of our then-outstanding shares of the capital stock entitled to vote generally at an election of directors;

provide that all vacancies, including newly created directorships, may, except as otherwise required by law, be filled by the affirmative vote of a majority of directors then in office, even if less than a quorum;

require that any action to be taken by our stockholders must be effected at a duly called annual or special meeting of stockholders and not be taken by written consent or electronic transmission;

provide that stockholders seeking to present proposals before a meeting of stockholders or to nominate candidates for election as directors at a meeting of stockholders must provide advance notice in writing, and also specify requirements as to the form and content of a stockholder’s notice;

provide that special meetings of our stockholders may be called only by the chairman of our board of directors, our chief executive officer or president or by our board of directors pursuant to a resolution adopted by a majority of the total number of authorized directors; and

not provide for cumulative voting rights, therefore allowing the holders of a majority of the shares of common stock entitled to vote in any election of directors to elect all of the directors standing for election, if they should so choose.

The amendment of any of these provisions requires approval by the holders of at least 66⅔% of the voting power of all of our then-outstanding common stock entitled to vote generally in the election of directors, voting together as a single class.

The combination of these provisions may make it more difficult for our existing stockholders to replace our board of directors as well as for another party to obtain control of us by replacing our board of directors. Because our board of directors has the power to retain and discharge our officers, these provisions could also make it more difficult for existing stockholders or another party to effect a change in management. In addition, the authorization of undesignated preferred stock makes it possible for our board of directors to issue preferred stock with voting or other rights or preferences that could impede the success of any attempt to change our control.

These provisions are intended to enhance the likelihood of continued stability in the composition of our board of directors and its policies and to discourage coercive takeover practices and inadequate takeover bids. These provisions are also designed to reduce our vulnerability to hostile takeovers and to discourage certain tactics that may be used in proxy fights. However, such provisions could have the effect of discouraging others from making tender offers for our shares and may have the effect of delaying changes in our control or management. As a consequence, these provisions may also inhibit fluctuations in the market price of our stock that could result from actual or rumored takeover attempts. We believe that the benefits of these provisions, including increased protection of our potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure our company, outweigh the disadvantages of discouraging takeover proposals, because negotiation of takeover proposals could result in an improvement of their terms.

Choice of Forum

Our Certificate of Incorporation and our Bylaws provide that the Court of Chancery of the State of Delaware is the sole and exclusive forum for any derivative action or proceeding brought on our behalf; any action asserting a breach of fiduciary duty to us or our stockholders; any action asserting a claim against us arising pursuant to any provision of the DGCL, our Certificate of Incorporation or our Bylaws; or any action asserting a claim against us that is governed by the internal affairs doctrine.

These exclusive forum provisions may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers, or other employees and may discourage these types of lawsuits. Furthermore, the enforceability of similar choice of forum provisions in other companies’ certificates of incorporation has been challenged in legal proceedings, and it is possible that, in connection with one or more actions or proceedings described above, a court could find the choice of forum provisions contained in our Certificate of Incorporation to be inapplicable or unenforceable.

Listing

Our common stock is listed on The Nasdaq Capital Market under the trading symbol “OTLK”. The applicable prospectus supplement will contain information, where applicable, as to any other listing, if any, on The Nasdaq Capital Market or any securities market or other exchange of the preferred stock or other securities covered by such prospectus supplement.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Equinti Trust Company, LLC. Its address is 48 Wall Street, Floor 23, New York, NY 10005.

DESCRIPTION OF DEBT SECURITIES

We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. While the terms we have summarized below will apply generally to any debt securities that we may offer under this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. The terms of any debt securities offered under a prospectus supplement may differ from the terms described below. Unless the context requires otherwise, whenever we refer to the indenture, we also are referring to any supplemental indentures that specify the terms of a particular series of debt securities.

We will issue the debt securities under the indenture that we will enter into with the trustee named in the indenture. The indenture will be qualified under the Trust Indenture Act of 1939, as amended, or the Trust Indenture Act. We have filed the form of indenture as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

The following summary of material provisions of the debt securities and the indenture is subject to, and qualified in its entirety by reference to, all of the provisions of the indenture applicable to a particular series of debt securities. We urge you to read the applicable prospectus supplements and any related free writing prospectuses related to the debt securities that we may offer under this prospectus, as well as the complete indenture that contains the terms of the debt securities.

General

The indenture does not limit the amount of debt securities that we may issue. It provides that we may issue debt securities up to the principal amount that we may authorize and may be in any currency or currency unit that we may designate. Except for the limitations on consolidation, merger and sale of all or substantially all of our assets contained in the indenture, the terms of the indenture do not contain any covenants or other provisions designed to give holders of any debt securities protection against changes in our operations, financial condition or transactions involving us.

We may issue the debt securities issued under the indenture as “discount securities,” which means they may be sold at a discount below their stated principal amount. These debt securities, as well as other debt securities that are not issued at a discount, may be issued with “original issue discount,” or OID, for U.S. federal income tax purposes because of interest payment and other characteristics or terms of the debt securities. Material U.S. federal income tax considerations applicable to debt securities issued with OID will be described in more detail in any applicable prospectus supplement.

We will describe in the applicable prospectus supplement the terms of the series of debt securities being offered, including:

the title of the series of debt securities;

any limit upon the aggregate principal amount that may be issued;

the maturity date or dates;

the form of the debt securities of the series;

the applicability of any guarantees;

whether or not the debt securities will be secured or unsecured, and the terms of any secured debt;

whether the debt securities rank as senior debt, senior subordinated debt, subordinated debt or any combination thereof, and the terms of any subordination;

if the price (expressed as a percentage of the aggregate principal amount thereof) at which such debt securities will be issued is a price other than the principal amount thereof, the portion of the principal amount thereof payable upon declaration of acceleration of the maturity thereof, or if applicable, the portion of the principal amount of such debt securities that is convertible into another security or the method by which any such portion shall be determined;

the interest rate or rates, which may be fixed or variable, or the method for determining the rate or rates and the date interest will begin to accrue, the dates interest will be payable and the regular record dates for interest payment dates or the method for determining such dates;

our right, if any, to defer payment of interest and the maximum length of any such deferral period;

if applicable, the date or dates after which, or the period or periods during which, and the price or prices at which, we may, at our option, redeem the series of debt securities pursuant to any optional or provisional redemption provisions and the terms of those redemption provisions;

the date or dates, if any, on which, and the price or prices at which we are obligated, pursuant to any mandatory sinking fund or analogous fund provisions or otherwise, to redeem, or at the holder’s option to purchase, the series of debt securities and the currency or currency unit in which the debt securities are payable;

the denominations in which we will issue the series of debt securities, if other than denominations of $1,000 and any integral multiple thereof;

any and all terms, if applicable, relating to any auction or remarketing of the debt securities of that series and any security for our obligations with respect to such debt securities and any other terms which may be advisable in connection with the marketing of debt securities of that series;

whether the debt securities of the series shall be issued in whole or in part in the form of a global security or securities, the terms and conditions, if any, upon which such global security or securities may be exchanged in whole or in part for other individual securities, and the depositary for such global security or securities;

if applicable, the provisions relating to conversion or exchange of any debt securities of the series and the terms and conditions upon which such debt securities will be so convertible or exchangeable, including the conversion or exchange price, as applicable, or how it will be calculated and may be adjusted, any mandatory or optional (at our option or the holders’ option) conversion or exchange features, the applicable conversion or exchange period and the manner of settlement for any conversion or exchange;

if other than the full principal amount thereof, the portion of the principal amount of debt securities of the series which shall be payable upon declaration of acceleration of the maturity thereof;

additions to or changes in the covenants applicable to the particular debt securities being issued, including, among others, the consolidation, merger or sale covenant;

additions to or changes in the events of default with respect to the securities and any change in the right of the trustee or the holders to declare the principal, premium, if any, and interest, if any, with respect to such securities to be due and payable;

additions to or changes in or deletions of the provisions relating to covenant defeasance and legal defeasance;

additions to or changes in the provisions relating to satisfaction and discharge of the indenture;

additions to or changes in the provisions relating to the modification of the indenture both with and without the consent of holders of debt securities issued under the indenture;

the currency of payment of debt securities if other than U.S. dollars and the manner of determining the equivalent amount in U.S. dollars;

whether interest will be payable in cash or additional debt securities at our or the holders’ option and the terms and conditions upon which the election may be made;

the terms and conditions, if any, upon which we will pay amounts in addition to the stated interest, premium, if any and principal amounts of the debt securities of the series to any holder that is not a “United States person” for federal tax purposes;

any restrictions on transfer, sale or assignment of the debt securities of the series; and

any other specific terms, preferences, rights or limitations of, or restrictions on, the debt securities, any other additions or changes in the provisions of the indenture, and any terms that may be required by us or advisable under applicable laws or regulations.

Conversion or Exchange Rights

We will set forth in the applicable prospectus supplement the terms on which a series of debt securities may be convertible into or exchangeable for our common stock or our other securities. We will include provisions as to settlement upon conversion or exchange and whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock or our other securities that the holders of the series of debt securities receive would be subject to adjustment.

Consolidation, Merger or Sale

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the indenture will not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise dispose of our assets as an entirety or substantially as an entirety. However, any successor to or acquirer of such assets (other than a subsidiary of ours) must assume all of our obligations under the indenture or the debt securities, as appropriate.

Events of Default under the Indenture

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the following are events of default under the indenture with respect to any series of debt securities that we may issue:

if we fail to pay any installment of interest on any series of debt securities, as and when the same shall become due and payable, and such default continues for a period of 90 days; provided, however, that a valid extension of an interest payment period by us in accordance with the terms of any indenture supplemental thereto shall not constitute a default in the payment of interest for this purpose;

if we fail to pay the principal of, or premium, if any, on any series of debt securities as and when the same shall become due and payable whether at maturity, upon redemption, by declaration or otherwise, or in any payment required by any sinking or analogous fund established with respect to such series; provided, however, that a valid extension of the maturity of such debt securities in accordance with the terms of any indenture supplemental thereto shall not constitute a default in the payment of principal or premium, if any;

if we fail to observe or perform any other covenant or agreement contained in the debt securities or the indenture, other than a covenant specifically relating to another series of debt securities, and our failure continues for 90 days after we receive written notice of such failure, requiring the same to be remedied and stating that such is a notice of default thereunder, from the trustee or holders of at least 25% in aggregate principal amount of the outstanding debt securities of the applicable series; and

if specified events of bankruptcy, insolvency or reorganization occur.

If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the trustee if notice is given by such holders, may declare the unpaid principal of, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default specified in the last bullet point above occurs with respect to us, the principal amount of and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the trustee or any holder.

The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the indenture. Any waiver shall cure the default or event of default.

Subject to the terms of the indenture, if an event of default under an indenture shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the trustee reasonable indemnity. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or power conferred on the trustee, with respect to the debt securities of that series, provided that:

the direction so given by the holder is not in conflict with any law or the applicable indenture; and

subject to its duties under the Trust Indenture Act, the trustee need not take any action that might involve it in personal liability or might be unduly prejudicial to the holders not involved in the proceeding.

A holder of the debt securities of any series will have the right to institute a proceeding under the indenture or to appoint a receiver or trustee, or to seek other remedies only if:

the holder has given written notice to the trustee of a continuing event of default with respect to that series;

the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series have made written request;

such holders have offered to the trustee indemnity satisfactory to it against the costs, expenses and liabilities to be incurred by the trustee in compliance with the request; and

the trustee does not institute the proceeding, and does not receive from the holders of a majority in aggregate principal amount of the outstanding debt securities of that series other conflicting directions within 90 days after the notice, request and offer.

These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

We will periodically file statements with the trustee regarding our compliance with specified covenants in the indenture.

Modification of Indenture; Waiver

We and the trustee may change an indenture without the consent of any holders with respect to specific matters:

to cure any ambiguity, defect or inconsistency in the indenture or in the debt securities of any series;

to comply with the provisions described above under “Description of Debt Securities—Consolidation, Merger or Sale;”

to provide for uncertificated debt securities in addition to or in place of certificated debt securities;

to add to our covenants, restrictions, conditions or provisions such new covenants, restrictions, conditions or provisions for the benefit of the holders of all or any series of debt securities, to make the occurrence, or the occurrence and the continuance, of a default in any such additional covenants, restrictions, conditions or provisions an event of default or to surrender any right or power conferred upon us in the indenture;

to add to, delete from or revise the conditions, limitations, and restrictions on the authorized amount, terms, or purposes of issue, authentication and delivery of debt securities, as set forth in the indenture;

to make any change that does not adversely affect the interests of any holder of debt securities of any series in any material respect;

to provide for the issuance of and establish the form and terms and conditions of the debt securities of any series as provided above under “Description of Debt Securities—General” to establish the form of any certifications required to be furnished pursuant to the terms of the indenture or any series of debt securities, or to add to the rights of the holders of any series of debt securities;

to evidence and provide for the acceptance of appointment under any indenture by a successor trustee; or

to comply with any requirements of the SEC in connection with the qualification of any indenture under the Trust Indenture Act.

In addition, under the indenture, the rights of holders of a series of debt securities may be changed by us and the trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series that is affected. However, unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, we and the trustee may make the following changes only with the consent of each holder of any outstanding debt securities affected:

extending the fixed maturity of any debt securities of any series;

reducing the principal amount, reducing the rate of or extending the time of payment of interest, or reducing any premium payable upon the redemption of any series of any debt securities; or

reducing the percentage of debt securities, the holders of which are required to consent to any amendment, supplement, modification or waiver.

Discharge

Each indenture provides that we can elect to be discharged from our obligations with respect to one or more series of debt securities, except for specified obligations, including obligations to:

provide for payment;

replace stolen, lost or mutilated debt securities of the series;

pay principal of and premium and interest on any debt securities of the series;

maintain paying agencies;

hold monies for payment in trust;

recover excess money held by the trustee;

compensate and indemnify the trustee; and

appoint any successor trustee.

In order to exercise our rights to be discharged, we must deposit with the trustee money or government obligations sufficient to pay all the principal of, any premium, if any, and interest on, the debt securities of the series on the dates payments are due.

Form, Exchange and Transfer

We will issue the debt securities of each series only in fully registered form without coupons and, unless we provide otherwise in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indenture provides that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company, or DTC, or another depositary named by us and identified in the applicable prospectus supplement with respect to that series. To the extent the debt securities of a series are issued in global form and as book-entry, a description of terms relating to any book-entry securities will be set forth in the applicable prospectus supplement.

At the option of the holder, subject to the terms of the indenture and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

Subject to the terms of the indenture and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will impose no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional security registrars or transfer agents or rescind the designation of any security registrars or transfer agent or approve a change in the office through which any security registrars or transfer agent acts, except that we will be required to maintain a security registrar and a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

issue, register the transfer of, or exchange any debt securities of that series during a period beginning at the opening of business 15 days before the day of mailing of a notice of redemption of any debt securities that may be selected for redemption and ending at the close of business on the day of the mailing; or

register the transfer of or exchange any debt securities so selected for redemption, in whole or in part, except the unredeemed portion of any debt securities we are redeeming in part.

Information Concerning the Trustee

The trustee, other than during the occurrence and continuance of an event of default under an indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture. Upon an event of default under an indenture, the trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs. Subject to this provision, the trustee is under no obligation to exercise any of the powers given it by the indenture at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur.

Payment and Paying Agents

Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest.

We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check that we will mail to the holder or by wire transfer to certain holders. Unless we otherwise indicate in the applicable prospectus supplement, we will designate the corporate trust office of the trustee as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We may at any time rescind the designation or any paying agent or approve a change in the office through which any paying agent acts, except that we will be required to maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the trustee for the payment of the principal of or any premium or interest on any debt securities that remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.

Governing Law

The indenture and the debt securities will be governed by and construed in accordance with the internal laws of the State of New York, except to the extent that the Trust Indenture Act is applicable.

DESCRIPTION OF WARRANTS

The following description, together with the additional information we may include in any applicable prospectus supplements and free writing prospectuses, summarizes the material terms and provisions of the warrants that we may offer under this prospectus, which may consist of warrants to purchase common stock, preferred stock or debt securities and may be issued in one or more series. Warrants may be issued independently or together with common stock, preferred stock or debt securities offered by any prospectus supplement and may be attached to or separate from those securities. While the terms we have summarized below will apply generally to any warrants that we may offer under this prospectus, we will describe the particular terms of any series of warrants that we may offer in more detail in the applicable prospectus supplement and any applicable free writing prospectus. The terms of any warrants offered under a prospectus supplement may differ from the terms described below. However, no prospectus supplement will fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness.

We have filed forms of the warrant agreements and forms of warrant certificates containing the terms of the warrants being offered as exhibits to the registration statement of which this prospectus is a part. We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of warrant agreement, if any, including a form of warrant certificate, that describes the terms of the particular series of warrants we are offering. The following summaries of material provisions of the warrants and the warrant agreements are subject to, and qualified in their entirety by reference to, all the provisions of the warrant agreement and warrant certificate applicable to the particular series of warrants that we may offer under this prospectus. We urge you to read the applicable prospectus supplements related to the particular series of warrants that we may offer under this prospectus, as well as any related free writing prospectuses, and the complete warrant agreements and warrant certificates that contain the terms of the warrants.

General

We will describe in the applicable prospectus supplement the terms of the series of warrants being offered, including, to the extent applicable:

the offering price and aggregate number of warrants offered;

the currency for which the warrants may be purchased;

the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each such security or each principal amount of such security;

in the case of warrants to purchase debt securities, the principal amount of debt securities purchasable upon exercise of one warrant and the price at, and currency in which, this principal amount of debt securities may be purchased upon such exercise;

in the case of warrants to purchase common stock or preferred stock, the number of shares of common stock or preferred stock, as the case may be, purchasable upon the exercise of one warrant and the price at which these shares may be purchased upon such exercise;

the effect of any merger, consolidation, sale or other disposition of our business on the warrant agreements and the warrants;

the terms of any rights to redeem or call the warrants;

any provisions for changes to or adjustments in the exercise price or number of securities issuable upon exercise of the warrants;

the dates on which the right to exercise the warrants will commence and expire;

the manner in which the warrant agreements and warrants may be modified;

a discussion of material or special U.S. federal income tax considerations of holding or exercising the warrants;

the terms of the securities issuable upon exercise of the warrants; and

any other specific terms, preferences, rights or limitations of or restrictions on the warrants.

Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:

in the case of warrants to purchase common stock or preferred stock, the right to receive dividends, if any, or, payments upon our liquidation, dissolution or winding up or to exercise voting rights, if any; or

in the case of warrants to purchase debt securities, the right to receive payments of principal of, or premium, if any, or interest on, the debt securities purchasable upon exercise or to enforce covenants in the applicable indenture.

Exercise of Warrants

Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to the specified time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information, and paying the required amount to the warrant agent in immediately available funds, as provided in the applicable prospectus supplement. We will set forth on the reverse side of the warrant certificate and in the applicable prospectus supplement the information that the holder of the warrant will be required to deliver to the warrant agent in connection with the exercise of the warrant.

Upon receipt of the required payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the securities purchasable upon such exercise. If fewer than all of the warrants represented by the warrant certificate are exercised, then we will issue a new warrant certificate for the remaining amount of warrants. If we so indicate in the applicable prospectus supplement, holders of the warrants may surrender securities as all or part of the exercise price for warrants.

Governing Law

Unless we provide otherwise in the applicable prospectus supplement, the warrants and warrant agreements, and any claim, controversy or dispute arising under or related to the warrants or warrant agreements, will be governed by and construed in accordance with the laws of the State of New York.

Enforceability of Rights by Holders of Warrants

Each warrant agent, if any, will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

LEGAL OWNERSHIP OF SECURITIES

We can issue securities in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have securities registered in their own names on the books that we or any applicable trustee, depositary or warrant agent maintain for this purpose as the “holders” of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names, as “indirect holders” of those securities. As we discuss below, indirect holders are not legal holders, and investors in securities issued in book-entry form or in street name will be indirect holders.

Book-Entry Holders

We may issue securities in book-entry form only, as we will specify in the applicable prospectus supplement. This means securities may be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary’s book-entry system. These participating institutions, which are referred to as participants, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.

Only the person in whose name a security is registered is recognized as the holder of that security. Securities issued in global form will be registered in the name of the depositary or its participants. Consequently, for securities issued in global form, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.

As a result, investors in a global security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary’s book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not legal holders, of the securities.

Street Name Holders

We may terminate a global security or issue securities in non-global form. In these cases, investors may choose to hold their securities in their own names or in “street name.” Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she maintains at that institution.

For securities held in street name, we or any applicable trustee or depositary will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we or any such trustee or depositary will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be indirect holders, not legal holders, of those securities.

Legal Holders

Our obligations, as well as the obligations of any applicable trustee or any third party employed by us or a trustee, run only to the legal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.

For example, once we make a payment or give a notice to the legal holder, we have no further responsibility for the payment or notice even if that legal holder is required, under agreements with its participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the holders to amend an indenture, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of an indenture, or for other purposes. In such an event, we would seek approval only from the legal holders, and not the indirect holders, of the securities. Whether and how the legal holders contact the indirect holders is up to the legal holders.

Special Considerations for Indirect Holders

If you hold securities through a bank, broker or other financial institution, either in book-entry form or in street name, you should check with your own institution to find out:

how it handles securities payments and notices;

whether it imposes fees or charges;

how it would handle a request for the holders’ consent, if ever required;

whether and how you can instruct it to send you securities registered in your own name so you can be a holder, if that is permitted in the future;

how it would exercise rights under the securities if there were a default or other event triggering the need for holders to act to protect their interests; and

if the securities are in book-entry form, how the depositary’s rules and procedures will affect these matters.

Global Securities

A global security is a security that represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.

Each security issued in book-entry form will be represented by a global security that we issue to, deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, DTC will be the depositary for all securities issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under the section titled “Special Situations When a Global Security Will Be Terminated.” As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a legal holder of the security, but only an indirect holder of a beneficial interest in the global security.

If the prospectus supplement for a particular security indicates that the security will be issued in global form only, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.

Special Considerations for Global Securities

The rights of an indirect holder relating to a global security will be governed by the account rules of the investor’s financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.

If securities are issued only in the form of a global security, an investor should be aware of the following:

an investor cannot cause the securities to be registered in his or her name, and cannot obtain non-global certificates for his or her interest in the securities, except in the special situations we describe below;

an investor will be an indirect holder and must look to his or her own bank or broker for payments on the securities and protection of his or her legal rights relating to the securities, as we describe above;

an investor may not be able to sell interests in the securities to some insurance companies and to other institutions that are required by law to own their securities in non-book-entry form;

an investor may not be able to pledge his or her interest in a global security in circumstances where certificates representing the securities must be delivered to the lender or other beneficiary of the pledge in order for the pledge to be effective;

the depositary’s policies, which may change from time to time, will govern payments, transfers, exchanges and other matters relating to an investor’s interest in a global security;

we and any applicable trustee have no responsibility for any aspect of the depositary’s actions or for its records of ownership interests in a global security, nor do we or any applicable trustee supervise the depositary in any way;

the depositary may, and we understand that DTC will, require that those who purchase and sell interests in a global security within its book-entry system use immediately available funds, and your bank or broker may require you to do so as well; and

financial institutions that participate in the depositary’s book-entry system, and through which an investor holds its interest in a global security, may also have their own policies affecting payments, transfers, exchanges, notices and other matters relating to the securities.

There may be more than one financial intermediary in the chain of ownership for an investor. We do not monitor and are not responsible for the actions of any of those intermediaries.

Special Situations When a Global Security Will Be Terminated

In a few special situations described below, a global security will terminate and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in securities transferred to their own name, so that they will be direct holders. We have described the rights of holders and street name investors above.

Unless we provide otherwise in the applicable prospectus supplement, a global security will terminate when the following special situations occur:

if the depositary notifies us that it is unwilling, unable or no longer qualified to continue as depositary for that global security and we do not appoint another institution to act as depositary within 90 days;

if we notify any applicable trustee that we wish to terminate that global security; or

if an event of default has occurred with regard to securities represented by that global security and has not been cured or waived.

The applicable prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the applicable prospectus supplement. When a global security terminates, the depositary, and neither we nor any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.

PLAN OF DISTRIBUTION

We may sell the securities covered hereby from time to time pursuant to underwritten public offerings, direct sales to the public, negotiated transactions, block trades or a combination of these methods. A distribution of these securities offered by this prospectus may also be effected through the issuance of derivative securities, including, without limitation, warrants. We may sell the securities to or through underwriters or dealers, through agents, or directly to one or more purchasers. We may distribute securities from time to time in one or more transactions:

·	at a fixed price or prices, which may be changed;

·	at market prices prevailing at the time of sale;

·	at prices related to such prevailing market prices; or

·	at negotiated prices.

We may also sell equity securities covered by this registration statement in an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act. Such offering may be made into an existing trading market for such securities in transactions at other than a fixed price, either:

·	on or through the facilities of The Nasdaq Capital Market or any other securities exchange or quotation or trading service on which such securities may be listed, quoted or traded at the time of sale; and/or

·	to or through a market maker other than on The Nasdaq Capital Market or such other securities exchanges or quotation or trading services.

Such at-the-market offerings, if any, may be conducted by underwriters acting as principal or agent.

A prospectus supplement or supplements (and any related free writing prospectus that we may authorize to be provided to you) will describe the terms of the offering of the securities, including, to the extent applicable:

·	the name or names of any underwriters, dealers or agents, if any;

·	the purchase price of the securities and the proceeds we will receive from the sale;

·	any options pursuant to which underwriters may purchase additional securities from us;

·	any agency fees or underwriting discounts and other items constituting agents’ or underwriters’ compensation;

·	any public offering price;

·	any discounts or concessions allowed or reallowed or paid to dealers; and

·	any securities exchange or market on which the securities may be listed.

Only underwriters named in the prospectus supplement will be underwriters of the securities offered by the prospectus supplement.

If underwriters are used in the sale, they will acquire the securities for their own account and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Subject to certain conditions, the underwriters will be obligated to purchase all of the securities offered by the prospectus supplement, other than securities covered by any option to purchase additional securities. Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may change from time to time. We may use underwriters with whom we have a material relationship. We will describe in the prospectus supplement, naming the underwriter, the nature of any such relationship.

We may sell securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities, and we will describe any commissions and other compensation we will pay the agent in the prospectus supplement. Unless the prospectus supplement states otherwise, our agent will act on a best-efforts basis for the period of its appointment.

We may authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

We may provide agents and underwriters with indemnification against civil liabilities related to this offering, including liabilities under the Securities Act, or contribution with respect to payments that the agents or underwriters may make with respect to these liabilities. Agents and underwriters may engage in transactions with, or perform services for, us in the ordinary course of business.

All securities we may offer, other than common stock, will be new issues of securities with no established trading market. Any agents or underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities. There is currently no market for any of the offered securities, other than our common stock which is listed on The Nasdaq Capital Market. We have no current plans for listing of the preferred stock, debt securities or warrants on any securities exchange or quotation system; any such listing with respect to any particular preferred stock, debt securities or warrants will be described in the applicable prospectus supplement or other offering materials, as the case may be.

Any underwriter may engage in overallotment, stabilizing transactions, short covering transactions and penalty bids in accordance with Rule 103 of Regulation M under the Exchange Act. Overallotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum. Short covering transactions involve purchases of the securities in the open market after the distribution is completed to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a stabilizing or covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time. These transactions may be effected on any exchange or over-the-counter market or otherwise.

Any agents and underwriters who are qualified market makers on The Nasdaq Capital Market may engage in passive market making transactions in the securities on The Nasdaq Capital Market in accordance with Rule 103 of Regulation M, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the securities. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker’s bid, however, the passive market maker’s bid must then be lowered when certain purchase limits are exceeded. Passive market making may stabilize the market price of the securities at a level above that which might otherwise prevail in the open market and, if commenced, may be discontinued at any time.

LEGAL MATTERS

Unless otherwise indicated in the applicable prospectus supplement, certain legal matters in connection with the offering and the validity of the securities offered by this prospectus, and any prospectus supplement thereto, will be passed upon by Cooley LLP, Chicago, Illinois. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

EXPERTS

The consolidated financial statements of Outlook Therapeutics, Inc. as of September 30, 2023 and 2022, and for the years then ended, have been incorporated by reference herein in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing. The audit report covering the September 30, 2023 consolidated financial statements contains an explanatory paragraph that states that the Company has incurred recurring losses and negative cash flows from operations and has an accumulated deficit, that raise substantial doubt about its ability to continue as a going concern. The consolidated financial statements do not include any adjustments that might result from the outcome of that uncertainty.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of a registration statement we filed with the SEC. This prospectus does not contain all of the information set forth in the registration statement and the exhibits to the registration statement. For further information with respect to us and the securities we are offering under this prospectus, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement. You should rely only on information contained in this prospectus or incorporated by reference into this prospectus. We have not authorized any person to provide you with different information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information in this prospectus is accurate as of any date other than the date on the front page of this prospectus, regardless of the time of delivery of this prospectus or any sale of the securities offered by this prospectus.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public at the SEC’s website at http://www.sec.gov.

We maintain a website at http://www.outlooktherapeutics.com. Information contained in or accessible through our website does not constitute a part of this prospectus.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to incorporate by reference the information we file with it, which means that we can disclose important information to you by referring you to another document that we have filed separately with the SEC. You should read the information incorporated by reference because it is an important part of this prospectus. Information in this prospectus supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus, while information that we file later with the SEC will automatically update and supersede the information in this prospectus. We incorporate by reference into this prospectus and the registration statement of which this prospectus is a part the information and documents listed below that we have filed with the SEC (Commission File No. 001-37759):

our Annual Report on Form 10-K for the fiscal year ended September 30, 2023, filed with the SEC on December 22, 2023, or the 2023 Form 10-K, and amended on January 24, 2024;

our Quarterly Report on Form 10-Q for the quarter ended December 31, 2023 filed with the SEC on February 14, 2024;

our Current Reports on Form 8-K, filed with the SEC on October 20, 2023, November 2, 2023, December 6, 2023, January 24, 2024, March 7, 2024, March 18, 2024 and March 26, 2024, to the extent the information in such reports is filed and not furnished; and

We also incorporate by reference any future filings (other than Current Reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items unless such Form 8-K expressly provides to the contrary) made with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (i) after the date of the filing of the registration statement of which this prospectus is a part and prior to effectiveness of the registration statement and (ii) after the effectiveness of the registration statement of which this prospectus is a part but prior to the termination of all offerings of securities covered by this prospectus (Commission File No. 001-37759). Information in such future filings updates and supplements the information provided in this prospectus. Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements.

We will furnish without charge to each person, including any beneficial owner, to whom a prospectus is delivered, upon written or oral request, a copy of any or all of the documents incorporated by reference into this prospectus but not delivered with the prospectus, including exhibits that are specifically incorporated by reference into such documents. You should direct any requests for documents to Outlook Therapeutics, Inc., Attention: Corporate Secretary, 485 Route 1 South, Building F, Suite 320, Iselin, New Jersey 08830. Our phone number is (609) 619-3990. You may also view the documents that we file with the SEC and incorporate by reference in this prospectus on our corporate website at www.outlooktherapeutics.com. The information on our website is not incorporated by reference and is not a part of this prospectus.

Shares of Common Stock

Pre-Funded Warrants to Purchase up to Shares of Common Stock

Shares of Common Stock Underlying Pre-Funded Warrants

Common Warrants to Purchase up to Shares of Common Stock

Shares of Common Stock Underlying Common Warrants

Placement Agent Warrants to Purchase up to Shares of Common Stock

Shares of Common Stock Underlying Placement Agent Warrants

PROSPECTUS SUPPLEMENT

H.C. Wainwright & Co.

, 2026

SEC Form 424B5 filed by Outlook Therapeutics Inc.