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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a)
of the Securities Exchange Act of 1934

Filed by the Registrant ☒

Filed by a Party other than the Registrant ☐

Check the appropriate box:

☐

Preliminary Proxy Statement

☐

Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

☒

Definitive Proxy Statement

☐

Definitive Additional Materials

☐

Soliciting Material Pursuant to § 240.14a-12

SELLAS LIFE SCIENCES GROUP, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement if Other Than the Registrant)

Payment of Filing Fee (Check the appropriate box):

☒

No fee required.

☐

Fee previously paid with preliminary materials.

☐

Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11.

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April 23, 2026

To Our Stockholders:

You are cordially invited to attend the 2026 Annual Meeting of Stockholders of SELLAS Life Sciences Group, Inc. (the “Company”) to be held at 8:30 a.m. Eastern Time on June 16, 2026 (the “2026 Annual Meeting”), unless postponed or adjourned to a later date. We will hold the 2026 Annual Meeting virtually as a live webcast at www.virtualshareholdermeeting.com/SLS2026. You will not be able to attend the 2026 Annual Meeting in person. Please refer to the proxy materials for more information on how to access the 2026 Annual Meeting.

The enclosed Notice of Annual Meeting of Stockholders sets forth the proposals that will be presented at the 2026 Annual Meeting, which are described in more detail in the enclosed Proxy Statement. Our Board of Directors recommends that you vote “FOR” Proposals 1, 2, 3, 4, and 5 as set forth in the Proxy Statement.

Under Securities and Exchange Commission rules that allow companies to furnish proxy materials to stockholders over the Internet instead of a printed copy of proxy materials, we have elected to deliver our proxy materials to our stockholders over the Internet. This delivery process allows us to provide stockholders with the information they need, while at the same time conserving natural resources and lowering the cost of delivery. On or about May 1, 2026, we expect to mail to our stockholders a Notice of Internet Availability of Proxy Materials (the “Notice”), which contains instructions on how to access our Proxy Statement and our Annual Report on Form 10-K for the year ended December 31, 2025. The Notice will also provide instructions on how to vote via the Internet as well as by telephone or mail.

We hope you will be able to attend the 2026 Annual Meeting. Whether you plan to attend the 2026 Annual Meeting or not, it is important that you cast your vote. When you have finished reading the Proxy Statement, we urge you to submit your vote so that your shares will be represented and voted at the 2026 Annual Meeting, whether or not you can attend.

On behalf of the Board and the management team, we thank you for your ongoing support of, and continued interest in, SELLAS Life Sciences Group, Inc.

				Very truly yours,

				Angelos M. Stergiou, M.D., Sc.D. h.c. President and Chief Executive Officer

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SELLAS LIFE SCIENCES GROUP, INC.
Times Square Tower, 7 Times Square, Suite 2503
New York, New York 10036

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To the Stockholders of SELLAS Life Sciences Group, Inc.:

You are invited to attend the 2026 Annual Meeting of Stockholders (“2026 Annual Meeting”) of SELLAS Life Sciences Group, Inc. (“SELLAS,” “we,” “us,” “our,” or “Company”) on June 16, 2026, at 8:30 a.m. Eastern Time. The 2026 Annual Meeting will be held exclusively online as a live webcast at www.virtualshareholdermeeting.com/SLS2026. There is no physical location for the 2026 Annual Meeting.

The 2026 Annual Meeting will be held for the following purposes, which are more fully described in the proxy statement accompanying this notice:

To elect two (2) Class I directors to serve on our Board of Directors for a three-year term expiring on the date on which our annual meeting of stockholders is held in 2029;

To ratify the appointment by our Audit Committee of Baker Tilly US, LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026;

To approve an amendment to the Company’s 2023 Amended and Restated Equity Incentive Plan (the “2023 Equity Plan”) to increase the number of shares of Common Stock authorized for issuance under the 2023 Equity Plan by 20,000,000 shares;

To approve, on a non-binding advisory basis, the compensation of the Company’s named executive officers; and

To approve any postponement or adjournment of the 2026 Annual Meeting, from time to time, if necessary, to solicit additional proxies if there are not sufficient votes at the time of the 2026 Annual Meeting to adopt the proposals set forth above or to establish a quorum.

In addition, stockholders may be asked to consider and vote upon such other business as may be properly brought before the meeting and any adjournment or postponement thereof.

Only stockholders of record of SELLAS common stock at the close of business on April 21, 2026, the record date, are entitled to notice of and to vote at the 2026 Annual Meeting and at any adjournments or postponements thereof. A list of stockholders of record will be available at the 2026 Annual Meeting and, during the 10 days prior to the annual meeting, at our principal executive offices located at Times Square Tower, 7 Times Square, Suite 2503, New York, New York 10036.

Important Notice Regarding Internet Availability of Proxy Materials for the Annual Meeting to be Held on June 16, 2026: SELLAS’ Proxy Statement and our Annual Report on Form 10-K for the year ended December 31, 2025 (the “2026 Annual Report”) are available at www.proxyvote.com. To access these proxy materials, please follow the instructions found on your Notice of Internet Availability of Proxy Materials (the “Notice”) or proxy card.

Your vote is important regardless of the number of shares of common stock you own. Whether or not you expect to attend the 2026 Annual Meeting, please submit your proxy by Internet, telephone, or mail by following the instructions found on the Notice or proxy card so that your shares of common stock may be represented and voted at the 2026 Annual Meeting.

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Regardless of the number of shares of common stock of the Company that you own, your vote is important. Thank you for your continued support, interest and investment in the Company.

By Order of the Board of Directors,

Stacy E. Yeung
Vice President, General Counsel &
Corporate Secretary

New York, New York
April 23, 2026

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	Page
Questions And Answers About These Proxy Materials And Voting		2
Security Ownership Of Certain Beneficial Owners And Management		9
Management And Corporate Governance		10
Board of Directors		10
Independence of the Board of Directors		12
Board Leadership Structure		13
Role of the Board in Risk Oversight		13
Corporate Governance Guidelines		13
Clawback Policy		14
Committees of the Board of Directors and Meeting Attendance		14
Executive Officer And Director Compensation		23
Summary Compensation Table		23
Narrative Disclosure to Summary Compensation Table		23
Outstanding Equity Awards At 2025 Fiscal Year-End		28
Director Compensation		32
Director Compensation Policy		32
Securities Authorized for Issuance Under Equity Compensation Plans		33
Related Person Transactions Policy and Procedures		34
Proposal 1: Election of Directors		35
Proposal 2: Appointment of Independent Registered Public Accounting Firm		36
Principal Accountant Fees and Services		36
Pre-Approval Procedures		37
Proposal 3: To Approve an Amendment to the Company’s 2023 Amended and Restated Equity Incentive Plan		38
Proposal 4: To Approve, on a Non-Binding Advisory Basis, the Compensation of our Named Executive Officers		46
Proposal 5: To Approve Any Postponement or Adjournment of the 2026 Annual Meeting, From Time to Time, if Necessary, to Solicit Additional Proxies if There Are Not Sufficient Votes at the Time of the 2026 Annual Meeting to Adopt the Proposals Set Forth Above or to Establish a Quorum		48
Other Matters		49

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SELLAS LIFE SCIENCES GROUP, INC.
Times Square Tower, 7 Times Square, Suite 2503
New York, New York 10036

PROXY STATEMENT

FOR THE ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON

Tuesday, June 16, 2026 at 8:30 a.m. (Eastern Time) via Live Webcast

In this Proxy Statement, “SELLAS,” the “Company,” “we,” “us,” and “our” refer to SELLAS Life Sciences Group, Inc., unless the context otherwise provides.

The 2026 Annual Meeting of Stockholders (the “2026 Annual Meeting”) to be held on Tuesday, June 16, 2026, beginning at 8:30 a.m. Eastern Time, will be held exclusively online via the Internet as a virtual webcast at: www.virtualshareholdermeeting.com/SLS2026. There will not be a physical meeting location.

Only stockholders of record at the close of business on April 21, 2026 (the “Record Date”) will be entitled to vote at the 2026 Annual Meeting. The Notice of Internet Availability of Proxy Materials (the “Notice”) containing instructions on how to access this Proxy Statement and the Annual Report on Form 10-K for the fiscal year ended December 31, 2025 (“2026 Annual Report”) is first being mailed to stockholders of record on or about May 1, 2026.

You may attend the 2026 Annual Meeting live online by visiting www.virtualshareholdermeeting.com/SLS2026, where you will be able to listen to the meeting live, submit questions, and vote online. The webcast will start at 8:30 a.m. Eastern Time, on June 16, 2026. To attend the 2026 Annual Meeting, vote online, and submit questions during the Annual Meeting, you will need the control number included in your Notice, voting instruction form, or proxy card. You may also attend the virtual meeting website as a “Guest.” Online access will open approximately 15 minutes before the start of the 2026 Annual Meeting. If you choose to request paper copies of proxy materials, the instructions for doing so can be found on the Notice and proxy card.

If you wish to submit a question before the meeting, you may send your question, along with proof of ownership of our common stock, to annualmeeting@sellaslife.com. Registered stockholders and beneficial owners may submit a question in writing during the 2026 Annual Meeting through the virtual meeting website. If you join the virtual meeting as a “Guest,” you will not be permitted to ask a question during the meeting. Our virtual meeting will be governed by our Annual Meeting Rules of Conduct, which will be posted at www.proxyvote.com in advance of the meeting.

Holders of our common stock at the close of business on April 21, 2026 will be entitled to vote at the 2026 Annual Meeting. As of April 21, 2026, 184,532,574 shares of our common stock were issued and outstanding and entitled to vote. Stockholders are entitled to one vote for each share of common stock held. A majority, or 92,266,288, of these shares, present in person or represented by proxy at the 2026 Annual Meeting, will constitute a quorum for the transaction of business.

The Notice of Annual Meeting of Stockholders, this Proxy Statement, our 2026 Annual Report, and the proxy card are also available on the Internet. Web links and addresses contained in this Proxy Statement are provided for convenience only, and the content on the referenced websites does not constitute a part of this Proxy Statement.

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QUESTIONS AND ANSWERS ABOUT THESE PROXY MATERIALS AND VOTING

Why is the Company soliciting my proxy?

Our Board of Directors (the “Board”) is soliciting your proxy to vote at the 2026 Annual Meeting to be held via live webcast, on June 16, 2026, at 8:30 a.m., Eastern Time, and any adjournments or postponements of the meeting. This Proxy Statement, along with the accompanying Notice of Annual Meeting of Stockholders, summarizes the purposes of the meeting and the information you need to know to vote at the 2026 Annual Meeting.

We intend to commence distribution of the Important Notice Regarding the Availability of Proxy Materials (the “Notice”) to stockholders on or about May 1, 2026, which, together with this Proxy Statement, the proxy card, and a copy of the 2026 Annual Report, are referred to as proxy materials. The proxy materials are available online at www.proxyvote.com.

You received the Notice because you owned shares of our common stock on April 21, 2026 (the “Record Date”).

Why did I receive a notice in the mail regarding the Internet availability of proxy materials instead of a full set of proxy materials?

As permitted by the rules of the U.S. Securities and Exchange Commission (the “SEC”) we may furnish our proxy materials to our stockholders by providing access to such documents on the Internet, rather than mailing printed copies of these materials to each stockholder. Stockholders will not receive printed copies of the proxy materials unless they request them. We believe that this process will expedite stockholders’ receipt of proxy materials, lower the costs of the 2026 Annual Meeting and help to conserve natural resources. If you received the Notice by mail or electronically, you will not receive a printed or email copy of the proxy materials, unless you request one by following the instructions included in the Notice. Instead, the Notice provides instructions on how you may access and review all of the proxy materials and submit your proxy via the Internet. If you requested a paper copy of the proxy materials, you may authorize the voting of your shares by following the instructions on the proxy card, in addition to the other methods of voting described in this Proxy Statement.

What proxy materials are available on the Internet?

This Proxy Statement and the 2026 Annual Report are available online at www.proxyvote.com. The Notice and proxy card contain additional information on how to access the proxy materials online or to request a paper copy.

How do I attend the 2026 Annual Meeting?

To attend the virtual 2026 Annual Meeting, visit www.virtualshareholdermeeting.com/SLS2026 on June 16, 2026 and follow the instructions included on your proxy card, your Notice, or voting instruction card. The meeting will begin promptly at 8:30 a.m. Eastern Time on June 16, 2026. We encourage you to access the meeting prior to the start time. Online access opens approximately 15 minutes before the start of the annual meeting. If you do not have your proxy card, Notice, or voting instruction card, you may join as a “Guest,” but you will not be able to vote or ask questions.

Who may vote at the 2026 Annual Meeting?

Only stockholders of record at the close of business on the Record Date will be entitled to vote at the 2026 Annual Meeting. On the Record Date, there were 184,532,574 shares of common stock issued and outstanding. Our common stock is our only class of voting stock.

A list of our stockholders of record will be open for examination by any stockholder beginning 10 days prior to the 2026 Annual Meeting at our headquarters located at 7 Times Square, Suite 2503, New York, NY 10036. If you would like to view the list, please contact our Corporate Secretary to schedule an appointment by writing to the Corporate Secretary at the address above. In addition, the list will be available

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for inspection by stockholders on the virtual meeting website during the Annual Meeting. Those who join the virtual annual meeting as a “Guest” will not be able to view the list of stockholders of record.

Stockholder of record: If, on the Record Date, your shares of SELLAS common stock were registered directly in your name with our transfer agent, Computershare Investor Services, then you are a stockholder of record. As stockholder of record, you may vote live online at the 2026 Annual Meeting or by proxy.

Beneficial holder or street name holder: If, on the Record Date, your shares of SELLAS common stock were held in an account by an intermediary, such as a bank, broker, or other agent, then you are the beneficial holder or street name holder. You should have received the proxy materials or Notice from your bank, broker, or other agent. As a beneficial holder, you have the right to direct your bank, broker, or other agent on how to vote your shares. Please follow the instructions provided by your bank, broker, or other agent on how to vote, or contact your broker, bank, or other agent to request a proxy form.

How do I submit questions?

You may submit questions in advance of the 2026 Annual Meeting by emailing the question, along with proof of stock ownership, to annualmeeting@sellaslife.com prior to 5:00 p.m. Eastern Time on Friday, June 12, 2026. If you are a stockholder of record, you may also submit questions during the 2026 Annual Meeting by visiting: www.virtualshareholdermeeting.com/SLS2026. We will, subject to time constraints, answer all questions that are pertinent to the business of the 2026 Annual Meeting and will give priority to questions submitted in advance. If you attend the 2026 Annual Meeting as a “Guest,” then you will not be permitted to submit questions during the meeting.

How do I vote?

Whether you plan to attend the 2026 Annual Meeting or not, we urge you to vote by proxy. All shares represented by valid proxies that we receive through this solicitation, and that are not revoked, will be voted in accordance with your instructions on the proxy card or as instructed via the Internet or telephone. If you properly submit a proxy without giving specific voting instructions, your shares will be voted in accordance with our Board’s recommendations as noted below. Voting by proxy will not affect your right to attend the 2026 Annual Meeting.

To cast your vote before the 2026 Annual Meeting, you may vote by one of the following methods:

				By Internet: Please follow the instructions on the proxy card or voting instructions sent to you. Your vote must be received by 11:59 p.m. Eastern Time on Monday, June 15, 2026, to be counted.
				By Telephone: To vote over the telephone, dial the number listed on the proxy card or voting instructions sent to you, and follow the instructions. Your vote must be received by 11:59 p.m. Eastern Time on Monday, June 15, 2026, to be counted.
				By Proxy by Mail: Mark, sign, and date your proxy card and mail the proxy to the address stated on the proxy card. If you return your signed proxy card to us before the 2026 Annual Meeting, we will vote your shares as you direct.

If you are a stockholder of record, you may also cast your vote during the 2026 Annual Meeting by accessing the annual meeting website and following the instructions on the Notice or proxy card.

If you are a beneficial holder, you should have received voting instructions from the bank, broker, or other agent. Follow the voting instructions you received from that intermediary to ensure that your vote is counted. To vote during the 2026 Annual Meeting, you must obtain a valid proxy from your bank, broker, or other agent. Follow the instructions from your bank, broker, or other agent included with the proxy materials, or contact your bank or broker to request a proxy form.

If you attend the annual meeting online as a “Guest,” you will not be able to cast your vote during the 2026 Annual Meeting.

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What is the difference between holding shares as a stockholder of record and as a beneficial holder/owner?

If, on the Record Date, your shares were registered directly in your name with our transfer agent, Computershare, then you are a stockholder of record. If, on the Record Date, your shares were not held in your name, but rather in an account at a brokerage firm, bank or other similar organization, then you are the beneficial owner of shares held in “street name.”

Stockholder of Record: Shares Registered in Your Name

If you are a stockholder of record, you may vote during the 2026 Annual Meeting, vote by proxy over the telephone or through the Internet, or vote by proxy using a proxy card.

Beneficial Owner: Shares Registered in the Name of Broker, Bank or Other Nominee

If you are a beneficial owner of shares registered in the name of your broker, bank, or other intermediary, you should have received a voting instruction form with the proxy materials from that organization rather than from us. To vote prior to the 2026 Annual Meeting, follow the instructions provided by your broker, bank, or other nominee. If you are a beneficial owner, your deadline for submitting your vote before the 2026 Annual Meeting is 11:59 p.m. Eastern Time on Monday, June 15, 2026.

What am I voting on?

This Proxy Statement describes the proposals on which we would like you, as a stockholder, to vote at the 2026 Annual Meeting. This Proxy Statement provides you with information on the proposals, as well as other information about us, so that you can make an informed decision as to whether and how to vote your stock.

At the 2026 Annual Meeting, stockholders will act upon the following five proposals:

	Proposal 1:			To elect two (2) Class I directors to serve on the Company’s Board of Directors for a three-year term expiring in 2029.
	Proposal 2:			To ratify the appointment by our Audit Committee of Baker Tilly US, LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026.
	Proposal 3:			To approve an amendment to the Company’s 2023 Amended and Restated Equity Incentive Plan (the “2023 Equity Plan”) to increase the number of shares of Common Stock authorized for issuance under the 2023 Equity Plan by 20,000,000 shares.
	Proposal 4:			To approve, on a non-binding advisory basis, the compensation of our named executive officers.
	Proposal 5:			To approve any postponement or adjournment of the 2026 Annual Meeting, from time to time, if necessary, to solicit additional proxies if there are not sufficient votes at the time of the 2026 Annual Meeting to adopt the proposals set forth above or to establish a quorum.

How does our Board of Directors recommend that I vote on the proposals?

Our Board of Directors recommends that you vote as follows:

•

“FOR” the election of the two (2) nominees for Class I directors to serve on the Company’s Board for a three-year term expiring in 2029.

•

“FOR” the ratification of the appointment of Baker Tilly US, LLP as our independent registered public accounting firm for our fiscal year ending December 31, 2026.

•

“FOR” the amendment to the Company’s 2023 Equity Plan to increase the number of shares of Common Stock authorized for issuance under the 2023 Equity Plan by 20,000,000 shares.

•

“FOR” the compensation of our named executive officers, as disclosed in this Proxy Statement.

•

“FOR” any postponement or adjournment of the 2026 Annual Meeting, from time to time, if necessary, to solicit additional proxies if there are not sufficient votes at the time of the 2026 Annual Meeting to adopt the proposals set forth above or to establish a quorum.

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How many votes do I have?

On each matter to be voted upon, you have one vote for each share of common stock you owned as of the Record Date.

What happens if I do not vote?

Stockholder of Record: Shares Registered in Your Name

If you are a stockholder of record and do not vote, your shares will not be voted.

Beneficial Owner: Shares Registered in the Name of Broker or Bank

If you are a beneficial owner of shares held in “street name” and you do not provide instructions on how to vote your shares, your broker, bank, or other nominee may still be able to vote your shares in its discretion. A broker, bank, or other nominee may generally vote in their discretion on routine matters. In this regard, Proposals 1, 3, and 4 are considered to be “non-routine,” meaning that if your broker, bank, or other nominee does not receive instructions from you on how to vote your shares on such non-routine matter, it will not have the authority to vote on the matter with respect to your shares. This is generally referred to as a “broker non-vote.” Therefore, broker non-votes may exist in connection with Proposals 1, 3, and 4. However, Proposals 2 and 5 are considered to be “routine” matters, meaning that if you do not return voting instructions to your broker, bank, or other nominee by its deadline, your shares may be voted by it in its discretion on Proposals 2 and 5.

What if I return a proxy card or otherwise vote but do not make specific choices?

If you return a signed and dated proxy card or otherwise vote without marking voting selections, your shares will be voted, as applicable:

•

“FOR” the election of the two (2) nominees for Class I directors to serve on the Company’s Board for a three-year term expiring in 2029.

•

“FOR” the ratification of the appointment of Baker Tilly US, LLP as our independent registered public accounting firm for our fiscal year ending December 31, 2026.

•

“FOR” the amendment to the Company’s 2023 Equity Plan to increase the number of shares of Common Stock authorized for issuance under the 2023 Equity Plan by 20,000,000 shares.

•

“FOR” the compensation of our named executive officers, as disclosed in this Proxy Statement.

•

If any other matter is properly presented at the 2026 Annual Meeting, your proxyholder will vote your shares using their best judgment.

Who is paying for this proxy solicitation?

We will pay for the entire cost of soliciting proxies. In addition to these proxy materials, our directors and employees may also solicit proxies in person, by telephone, or by other means of communication. Directors and employees will not be paid any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks and other nominees for the cost of forwarding proxy materials to beneficial owners. We have retained Alliance Advisors to act as a proxy solicitor in conjunction with the 2026 Annual Meeting. We have agreed to pay Alliance Advisors $30,000, plus reasonable out-of-pocket expenses, for proxy solicitation services.

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Can I change my vote after submitting my proxy?

Stockholder of Record: Shares Registered in Your Name

Yes. You can revoke your proxy at any time before the final vote at the 2026 Annual Meeting. If you are the record holder of your shares, you may revoke your proxy in any one of the following ways:

•

You may submit another properly completed proxy card with a later date.

•

You may grant a subsequent proxy by telephone or through the Internet.

•

You may send a timely written notice that you are revoking your proxy to our Corporate Secretary at SELLAS Life Sciences Group, Inc., Times Square Tower, 7 Times Square, Suite 2503, New York, New York 10036.

•

You may cast a vote online at the meeting.

Your most current proxy card or telephone or Internet proxy is the one that is counted.

Beneficial Owner: Shares Registered in the Name of Broker or Bank

If your shares are held by your broker, bank, or other nominee, you should follow the instructions provided by your broker, bank or other nominee.

How are votes counted?

Votes will be counted by the inspector of election appointed for the 2026 Annual Meeting, who will separately count, with respect to (i) Proposal 1, votes “For,” “Withhold,” and broker non-votes; and (ii) Proposals 2, 3, 4, and 5 votes “For” and “Against,” abstentions, and, if applicable, broker non-votes.

What are “broker non-votes”?

As discussed above, when a beneficial owner of shares held in “street name” does not give instructions to his or her broker, bank or nominee holding the shares as to how to vote on matters deemed to be “non-routine” under NYSE rules, the broker, bank or nominee cannot vote the shares. These unvoted shares are counted as “broker non-votes.” Proposals 1, 3, and 4 are considered to be “non-routine” under NYSE rules and we, therefore, expect broker non-votes to exist in connection with those proposals.

As a reminder, if you are a beneficial owner of shares held in “street name,” in order to ensure your shares are voted in the way you would prefer, you must provide voting instructions to your broker, bank, or other nominee holding the shares by the deadline provided in the materials you receive from your broker or bank.

How many votes are needed to approve each proposal?

The holders of a majority of the shares of our common stock issued and outstanding and entitled to vote at the 2026 Annual Meeting will constitute a quorum for the transaction of business at the 2026 Annual Meeting. Shares of common stock represented in person or by proxy (including shares which abstain or do not vote with respect to one or more of the matters presented for stockholder approval) will be counted for purposes of determining whether a quorum is present at the 2026 Annual Meeting. The following votes are required for approval of the proposals being presented at the 2026 Annual Meeting:

Proposal 1: To Elect Two (2) Class I Directors. Directors are elected by a plurality of the votes of the holders of shares present in person or represented by proxy and entitled to vote on the election of directors. Accordingly, the two nominees receiving the highest number of affirmative votes will be elected. The nominees for Class I directors to be considered at the 2026 Annual Meeting are Robert Van Nostrand and Jane Wasman. Shares represented by executed proxies will be voted, if authority to do so is not withheld, for the election of the foregoing Class I directors.

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Proposal 2: To Ratify the Appointment by the Audit Committee of Baker Tilly US, LLP as our Independent Registered Public Accounting Firm for the Fiscal Year Ending December 31, 2026. A majority of the votes cast is required for the ratification of the appointment of Baker Tilly US, LLP as our independent registered public accounting firm for the current fiscal year.

Proposal 3: To Approve an Amendment to the Company’s 2023 Amended and Restated Equity Incentive Plan (the “2023 Equity Plan”) to increase the number of shares of Common Stock authorized for issuance under the 2023 Equity Plan by 20,000,000 shares. A majority of the votes cast is required for the approval of the amendment to the 2023 Equity Plan.

Proposal 4: To Approve, on a Non-Binding Advisory Basis, the Compensation of our Named Executive Officers. This proposal calls for a non-binding advisory vote, and accordingly there is no “required vote” that would constitute approval. However, our Board, including our compensation committee, values the opinion of our stockholders and we will consider our stockholders’ concerns to the extent there are a substantial number of votes cast against the executive officer compensation as disclosed in this Proxy Statement and evaluate what actions may be appropriate to address those concerns.

Proposal 5: To approve any postponement or adjournment of the 2026 Annual Meeting, from time to time, if necessary, to solicit additional proxies if there are not sufficient votes at the time of the 2026 Annual Meeting to adopt the proposals set forth above or to establish a quorum. A majority of the votes present or represented by proxy and entitled to vote at the 2026 Annual Meeting is required to approve any postponement or adjournment of the 2026 Annual Meeting, from time to time, if necessary, to solicit additional proxies if there are not sufficient votes at the time of the 2026 Annual Meeting to adopt the proposals set forth above or to establish a quorum.

Shares that abstain from voting as to a particular matter and shares held in “street name” by brokerage firms who indicate on their proxies that they do not have discretionary authority to vote such shares as to a particular matter will not be counted as votes cast on such matter. Accordingly, abstentions and “broker non-votes” will have no effect on the voting on Proposals 1, 3, and 4. Brokerage firms have authority to vote customers’ unvoted shares held by the firms in “street name” on Proposals 2 and 5. If a broker does not exercise this authority, such broker non-votes will have no effect on the results of this vote; abstentions will have no effect on the results of Proposal 2 and will have the effect of a vote against on the results of Proposal 5.

What is the quorum requirement?

A quorum of stockholders is necessary to hold a valid meeting. A quorum will be present if stockholders holding at least a majority of our outstanding shares of the common stock entitled to vote are present at the 2026 Annual Meeting in person or represented by proxy. On the Record Date, there were 184,532,574 shares issued and outstanding and entitled to vote.

Your shares will be counted towards the quorum only if you submit a valid proxy (or one is submitted on your behalf by your broker, bank or other nominee) or if you cast your vote online. If there is no quorum, the holders of a majority of shares present at the 2026 Annual Meeting or represented by proxy may adjourn the 2026 Annual Meeting to another date.

How can I find out the 2026 Annual Meeting voting results?

Preliminary voting results will be announced at the 2026 Annual Meeting. In addition, final voting results will be published in a Current Report on Form 8-K that we expect to file within four business days following the 2026 Annual Meeting. If final voting results are not available to us in time to file a Current Report on Form 8-K within four business days following the 2026 Annual Meeting, we intend to file a Current Report on Form 8-K to publish preliminary results and, within four business days following the final results are known to us, file an additional Current Report on Form 8-K to publish the final results.

What if I receive more than one notice or proxy card?

You may receive more than one Notice or proxy card if you hold shares of our common stock in more than one account, which may be in registered form or held in street name. Please vote in the manner described above under “How Do I Vote?” for each account to ensure that all of your shares of our common stock are voted.

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How may I obtain an additional copy of the proxy materials if I share an address with another stockholder?

Some brokers or other nominee record holders may be sending you a single Notice or, if applicable, a single set of our proxy materials if multiple stockholders of the Company live in your household. This practice, which has been approved by the SEC, is called “householding.” Once you receive notice from your broker or other nominee record holder that it will be “householding” the Notice or if, applicable, our proxy materials, the practice will continue until you are otherwise notified or until you notify them that you no longer want to participate in the practice. Stockholders who participate in householding will continue to have access to and utilize separate proxy voting instructions.

We will promptly deliver a separate copy of our Notice or if applicable, our proxy materials to you if you write to our Corporate Secretary at: SELLAS Life Sciences Group, Inc., Times Square Tower, 7 Times Square, Suite 2503, New York, NY 10036, (646) 200-5278. If you want to receive your own Notice or, if applicable, set of our proxy materials in the future or, if you share an address with another stockholder and together both of you would like to receive only a single Notice or, if applicable, set of proxy materials, you should contact your broker or other nominee record holder directly or you may contact us at the above address and phone number.

When are stockholder proposals and director nominations due for next year’s annual meeting?

Proposals of stockholders intended to be presented at next year’s annual meeting of stockholders pursuant to Rule 14a-8 promulgated under the Securities Exchange Act of 1934, as amended (the “Exchange Act”) must be received by us at our principal offices, Times Square Tower, 7 Times Square, Suite 2503, New York, New York 10036, Attention: Corporate Secretary, no later than December 23, 2026, the date that is 120 days prior to the first anniversary of the date of this Proxy Statement, in order to be included in the proxy statement and proxy card relating to that meeting.

If a stockholder wishes to present a proposal at our 2026 Annual Meeting, but does not wish to have the proposal considered for inclusion in our proxy statement and proxy card, pursuant to the advance notice provision in our bylaws, such stockholder must give written notice to our Corporate Secretary at our principal executive offices at the address noted above. The Corporate Secretary must receive such notice no earlier than February 16, 2027, and no later than March 18, 2027, provided that if the date of the annual meeting of stockholders is held before June 16, 2027, such notice must instead be received by the Corporate Secretary no earlier than the 120th day prior to the annual meeting of stockholders and not later than the close of business on the 90th day prior to the annual meeting of stockholders or the 10th day following the day on which public disclosure of the date of such annual meeting is first made by us in order for such notice to be timely.

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SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The following table sets forth certain information with respect to the beneficial ownership of our common stock as of April 15, 2026 for (i) the named executive officers named in the Summary Compensation Table on page 23 of this Proxy Statement, (ii) each of our directors and director nominees, (iii) all of our current directors and executive officers as a group and (iv) each stockholder known by us to own beneficially more than 5% of our common stock. Beneficial ownership is determined in accordance with the rules of the SEC and includes voting or investment power with respect to the securities. We deem shares of common stock that may be acquired by an individual or group within 60 days of April 15, 2026 pursuant to the exercise of options or warrants or the vesting of restricted stock units to be outstanding for the purpose of computing the percentage ownership of such individual or group, but those shares are not deemed to be outstanding for the purpose of computing the percentage ownership of any other person shown in the table. Except as indicated in footnotes to this table, we believe that the stockholders named in this table have sole voting and investment power with respect to all shares of common stock shown to be beneficially owned by them based on information provided to us by these stockholders. Percentage of ownership is based on 184,532,574 shares of common stock outstanding April 15, 2026.

Name of Beneficial Owner

Number

Percentage of
Shares
Beneficially
Owned

Directors and Executive Officers:

Angelos M. Stergiou, President, Chief Executive Officer and Director

1,133,328(1)

Dragan Cicic, Senior Vice President, Chief Development Officer

401,224(2)

John T. Burns, Senior Vice President, Chief Financial Officer

364,104(3)

John Varian, Chair of the Board

82,855(4)

David L. Scheinberg, Director

83,037(5)

Robert Van Nostrand, Director

92,855(6)

Jane Wasman, Director

102,855(7)

Katherine Bach Kalin, Director

161,400(8)

All current executive officers and directors as a group (8 persons)

2,421,658

1.3%

Represents beneficial ownership of less than one percent (1%) of the outstanding common stock.

(1)

Represents 312,433 shares of our common stock and options to purchase 820,895 shares of our common stock exercisable within 60 days.

(2)

Represents 126,443 shares of our common stock and options to purchase 274,781 shares of our common stock exercisable within 60 days.

(3)

Represents 132,373 shares of our common stock and options to purchase 231,731 shares of our common stock exercisable within 60 days.

(4)

Represents 22,900 shares of our common stock and options to purchase 59,955 shares of our common stock exercisable within 60 days.

(5)

Represents 23,082 shares of our common stock and options to purchase 59,955 shares of our common stock exercisable within 60 days.

(6)

Represents 32,900 shares of our common stock and options to purchase 59,955 shares of our common stock exercisable within 60 days.

(7)

Represents 42,900 shares of our common stock and options to purchase 59,955 shares of our common stock exercisable within 60 days.

(8)

Represents 104,400 shares of our common stock and options to purchase 57,000 shares of our common stock exercisable within 60 days.

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MANAGEMENT AND CORPORATE GOVERNANCE

Board of Directors

Our Amended and Restated Bylaws provide that our business shall be managed by or under the direction of our Board. Our Board is divided into three classes for purposes of election. One class is elected at each annual meeting of stockholders to serve for a three-year term. The size of our Board had been set at six members since 2022. The Board is currently classified into three classes as follows: (i) Robert Van Nostrand and Jane Wasman are members of Class I with a term ending at the 2026 Annual Meeting; (ii) Katherine Bach Kalin and David A. Scheinberg are members of Class II with a term ending at the 2027 annual meeting; and (iii) Angelos M. Stergiou and John Varian are members of Class III with a term ending at the 2028 annual meeting.

Our Board, upon the recommendation of the Nominating and Corporate Governance Committee, has nominated each of Robert Van Nostrand and Jane Wasman for election at the 2026 Annual Meeting as a Class I director for a term of three years to serve until the 2029 annual meeting of stockholders, and until their successors have been elected and qualified.

Set forth below are the names of (i) the persons nominated for election as directors, and (ii) those directors whose terms do not expire this year, their ages, their offices in the Company, if any, their principal occupations or employment for at least the past five years, the length of their tenure as directors and the names of other public companies in which such persons hold or have held directorships during the past five years as of April 15, 2026. Additionally, information about the specific experience, qualifications, attributes or skills that led to our Board’s conclusion at the time of filing of this Proxy Statement that each person listed below should serve as a director is set forth below.

John Varian. Mr. Varian has been a director of the Company since December 2017 and Chair of the Board since June 2024. He was the Chair of the Audit Committee from December 2017 to June 2023 and remains a member. He was Chair of the Compensation Committee from June 2023 to June 2024 and remains a member. Mr. Varian served as Chief Executive Officer of XOMA Corporation (NASDAQ: XOMA) from August 2011 through December 2016 and served as a member of the board of directors of XOMA from December 2008 through May 2017. Mr. Varian served as a member of the board of directors of Acorda Therapeutics, Inc. (NASDAQ: ACOR) from January 2022 to August 2024, when its assets were sold to Merz Therapeutics, the board of directors of Versartis, Inc. (NASDAQ: VSAR) from March 2014 through October 2018, when it acquired Aravive, and the board of directors of Egalet Corporation (NASDAQ: EGLT) from June 2018 through February 2019, when it acquired the assets of Iroko. Mr. Varian has also been a director on the board of AmMax Bio, Inc. (a privately held clinical stage biotechnology company) since February 2021. Mr. Varian previously served as Chief Operating Officer of ARYx Therapeutics, Inc. from December 2003 through August 2011. Beginning in May 2000, Mr. Varian was Chief Financial Officer of Genset S.A. in France, where he was a key member of the team negotiating Genset’s sale to Serono S.A. in 2002. From 1998 to 2000, Mr. Varian served as Senior Vice President, Finance and Administration of Elan Pharmaceuticals, Inc., joining the company as part of its acquisition of Neurex Corporation. Prior to the acquisition, he served as Neurex Corporation’s Chief Financial Officer from 1997 until 1998. From 1991 until 1997, Mr. Varian served as the VP Finance and Chief Financial Officer of Anergen Inc. Mr. Varian was an Audit Principal/Senior Manager at Ernst & Young LLP from 1987 until 1991, where he focused on life sciences. Mr. Varian was also a founding committee member of Bay Bio and a former chairman of the Association of Bioscience Financial Officers International Conference. Mr. Varian holds a BBA from Western Michigan University. He was a Certified Public Accountant. The Company believes Mr. Varian’s significant experience working with biopharmaceutical companies, including developing and implementing strategy, with a focus on drug development, financing, corporate financial management, and related matters, qualifies him to serve on our Board.

Katherine Bach Kalin. Ms. Kalin has been a director of the Company since August 2022. She has been Chair of the Compensation Committee since June 2024 and a member of the Nominating and Corporate Governance Committee since October 2022. Ms. Kalin currently serves as a non-executive director on the boards of Genfit S.A., a French, public biopharmaceutical company, where she serves on the Strategy and Alliances Committee and the ESG Committee, and two private companies, Brown Advisory LLC, an independent investment and strategic advisory firm (Audit & Finance Committees), and

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FemHealth Ventures, a venture capital firm that seeks to invest in women’s health. She was a member of the board of directors of Athersys, Inc. (OTC: ATHX), a biotech focused on regenerative medicine from 2020 to 2022 (Audit and Compensation Committees) and Clinical Genomics, a private, biotech company dedicated to improving patient outcomes through early detection of colorectal cancer (Audit and Financial Risk Committee) from 2018 to 2021. Ms. Kalin has more than 25 years of experience in healthcare and professional services. At Celgene, she led Corporate Strategy from 2012 to 2017, and at Johnson & Johnson, she held executive leadership roles in marketing, sales and new business development from 2002 to 2011. Prior to that, Ms. Kalin was a partner in the global healthcare practice at McKinsey & Co., from 1990 to 2002. Her healthcare industry experience spans pharmaceuticals, diagnostics, medical devices, and digital health. Earlier in her career, she served as a Manager in Corporate Finance at Nomura International in the U.K. and Japan from 1984 to 1988. She has a B.A. from Durham University, U.K. and an M.B.A. from Harvard Business School. The Company believes Ms. Kalin’s healthcare industry experience, business strategy, and marketing expertise as well as her past and present experience on the board of other publicly traded companies, qualifies her to serve on our Board.

Angelos M. Stergiou, M.D., Sc.D. h.c. Dr. Stergiou has served as our President and Chief Executive Officer, and a director, since December 2017. Dr. Stergiou founded, in 2012, our predecessor entity, or Private SELLAS, that completed a business combination with Galena Biopharma on December 29, 2017, and served as the President and Chief Executive Officer and a director since that time, both as Chairman from 2012 to July 2016, and as Vice Chairman from July 2016 to December 2017. In connection therewith, Dr. Stergiou led the negotiation of an exclusive license agreement with Memorial Sloan Kettering Cancer Center (“MSK”) to develop and commercialize MSK’s WT1 peptide vaccine technology, which was satisfied in part by the transfer to MSK of certain of Dr. Stergiou’s shares in Private SELLAS. Dr. Stergiou also co-founded Genesis Life Sciences, Ltd. (now Genesis Research), a boutique health economics and pricing-reimbursement and health access company where he served as President and Chief Operating Officer from 2009 to 2011. From 2004 to 2008, Dr. Stergiou served as Vice President and Head of Drug Development at Accentia Biopharmaceuticals, Inc. and also served in the same capacity as well as Chief Medical Officer at its subsidiary Biovest International, Inc. during the same time. While at Biovest International, Inc., Dr. Stergiou led the Phase 3 development of a therapeutic cancer vaccine, BiovaxID, which was presented at the American Society of Clinical Oncology plenary session in 2009. Dr. Stergiou started his biotechnology career in 2002 at PAION AG where he served as its U.S. program lead of desmoteplase (DEDAS) and served on the joint steering and oversight committee of PAION AG with Forest Laboratories, Inc. in 2003-2004. Dr. Stergiou holds an M.D. from the U.S. American Institute of Medicine and a Sc.D. h.c. from Kentucky Wesleyan College and received his undergraduate degree in pre-medicine, biology and chemistry from Kentucky Wesleyan College. Dr. Stergiou was a member of the Board of Trustees at Kentucky Wesleyan College from March 2017 to January 2021, and is a Fellow of the Royal Society of Medicine, an active member of the World Medical Association, and a member of the American Academy of Physicians in Clinical Research and the Association of Clinical Research Professionals. Dr. Stergiou has served on the Board of Directors of Cleara Biotech B.V., a private biotech company located in the Netherlands, since January 2022. The Company believes that Dr. Stergiou’s experience as the founder of Private SELLAS and as President, Chief Executive Officer and Director of the Company, as well as his extensive experience in the biopharmaceutical industry and his significant management experience, qualifies him to serve on our Board.

David A. Scheinberg, M.D., Ph.D. Dr. Scheinberg has been a director of the Company and Chair of the Science Committee since December 2017. Dr. Scheinberg is currently the Vincent Astor Chair and Chairman of the Center for Experimental Therapeutics at Memorial Sloan Kettering Cancer Center (MSK) and is the Deputy Director of the Sloan Kettering Institute for Therapeutic Discovery, where he spearheaded the discovery and early clinical development of galinpepimut-S. Additionally, Dr. Scheinberg is a Professor of Medicine and Pharmacology and until 2022, was co-chair of the Pharmacology graduate program at the Weill-Cornell University Medical College. He is a Professor in the Gerstner-Sloan Kettering Graduate School at MSK. Dr. Scheinberg is also an attending physician in the Department of Medicine, on the Leukemia Service, which he led as Chief from 1992 to 2001. Dr. Scheinberg has been an advisor to charitable foundations, cancer centers and elite universities. He sat on the board of directors of Progenics Pharmaceuticals, Inc., a biotechnology company, from 1996 to 2019, which then merged with Lantheus (NASDAQ: LNTH), and currently sits on the board of directors of Sapience Therapeutics, Inc., a privately held, clinical stage biotechnology company. Dr. Scheinberg also served on Private SELLAS’ Scientific

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Advisory Board from 2015 to 2017. From 2010 through 2016, he served on the board of directors of Contrafect Corporation, a publicly traded clinical-stage biotechnology company. Dr. Scheinberg holds an M.D. and a Ph.D. in Pharmacology and Experimental Therapeutics from the Johns Hopkins University School of Medicine. Dr. Scheinberg earned his undergraduate degree in Biology from Cornell University. The Company believes Dr. Scheinberg’s experience on Private SELLAS’ Scientific Advisory Board and other public board experience, as well as his expertise as a leading academic oncologist and drug developer at MSK, including broad knowledge of and contacts in the highest levels of medical research, qualifies him to serve on our Board.

Robert L. Van Nostrand. Mr. Van Nostrand has been a director of the Company since December 2017. He was Chair of the Compensation Committee from December 2017 to June 2023. In June 2023, Mr. Van Nostrand became Chair of the Audit Committee and he has been a member of the Nominating and Corporate Governance Committee since 2018. He was a member of the board of directors and lead outside director of Intra-Cellular Therapies, Inc. (NASDAQ: ITCI), a biopharmaceutical company, until it was acquired in April 2025, and chairman of the board of directors of Yield10 Bioscience, Inc. (NASDAQ: YTEN), a bio-agricultural bioscience company which filed a voluntary petition for relief under Chapter 11 of Title 11 of the U.S. Bankruptcy Code in December 2024. He was a member of the board of directors of Achillion Pharmaceuticals, Inc. (NASDAQ: ACHN), a biotechnology company, until it was acquired in January 2020. Mr. Van Nostrand is also a member of the board of directors of Likeminds, Inc., a private biotech company, and the Biomedical Research Alliance of New York, a private company providing clinical trial services. Mr. Van Nostrand was Executive Vice President and Chief Financial Officer of Aureon Laboratories, Inc., a pathology life science company, from January 2010 to July 2010. Prior to joining Aureon Laboratories, Mr. Van Nostrand served as Executive Vice President and Chief Financial Officer of AGI Dermatics, a private biotechnology company, from July 2007 to September 2008, when the company was acquired. Between 1986 and 2007, Mr. Van Nostrand held various executive and other management positions, including Chief Financial Officer and Chief Compliance Officer at OSI Pharmaceuticals, Inc. (“OSI”), then a public biotechnology company focused on oncology. Prior to joining OSI, Mr. Van Nostrand served in a managerial position with the accounting firm, Touche Ross & Co., currently Deloitte. He is a treasurer and member of the board of NewYorkBIO. Mr. Van Nostrand holds a B.S. in Accounting from Long Island University, New York and completed advanced management studies at the Wharton School of the University of Pennsylvania. He was a Certified Public Accountant. The Company believes Mr. Van Nostrand’s vast board and industry experience in life sciences, his qualification as a financial expert, as well as his experience in transaction structuring and risk management qualifies him to serve on our Board.

Jane Wasman. Ms. Wasman has been a director of the Company since December 2017 and served as Chair of the Board from December 2017 through June 2024. Ms. Wasman has served as Chair of the Nominating and Corporate Governance Committee of the Board since December 2017, became a member of the Audit Committee in 2019, and previously served as a member of the Compensation Committee. Ms. Wasman was President, International & General Counsel of Acorda Therapeutics, Inc., a publicly traded biopharmaceutical company, from October 2012 until December 2019, managing its international, legal, quality, IP and compliance functions. From January 2012 until October 2012, she was Acorda’s Chief, Strategic Development, General Counsel and Corporate Secretary, and from May 2005 until January 2012, she was Acorda’s Executive Vice President, General Counsel and Corporate Secretary. Before joining Acorda, Ms. Wasman was with Schering-Plough Corporation, a global pharmaceutical company, for over eight years, holding various U.S. and international leadership positions, including Staff Vice President and Associate General Counsel. Ms. Wasman earned a J.D. from Harvard Law School and her undergraduate degree magna cum laude from Princeton University. Ms. Wasman is also a member of the board of directors of Rigel Pharmaceuticals, Inc. (NASDAQ: RIGL), a publicly traded biopharmaceutical company. She previously served as chair of the board of Athersys, Inc. (OTC: ATHX), a publicly traded biopharmaceutical company, and a member of the boards of Cytovia Therapeutics, a private company, and NewYorkBIO (including its Executive Committee). The Company believes Ms. Wasman’s significant executive and management experience at publicly traded biopharmaceutical companies qualifies her to serve on our Board.

Independence of the Board of Directors

As required under Nasdaq listing standards, a majority of the members of a listed company’s board of directors must qualify as “independent,” as affirmatively determined by the board of directors of such listed

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company. Our Board consults with our internal and outside counsel to ensure that its determinations are consistent with relevant securities and other laws and regulations regarding the definition of “independent,” including those set forth in pertinent listing standards of Nasdaq, as in effect from time to time.

Consistent with these considerations, after review of all relevant identified transactions or relationships between each director, or any of his or her family members, and us, our senior management and our independent auditors, our Board has affirmatively determined that the following directors are independent directors within the meaning of the applicable Nasdaq listing standards: Robert L. Van Nostrand and Jane Wasman, each Class I directors, Katherine Bach Kalin and David A. Scheinberg, M.D., Ph.D., each Class II directors, and John Varian, a Class III director. In making this determination, our Board found that none of these directors had a material or other disqualifying relationship with the Company. Dr. Stergiou, who is a Class III director, is an employee and is therefore not “independent.”

Board Leadership Structure

Our Board has an independent Chair, John Varian, who began serving as Chair in June 2024, and has authority, among other things, to preside over Board meetings and stockholder meetings, and shall have such powers and duties as may from time to time be assigned by the Board. Accordingly, the Chair has substantial ability to shape the work of the Board. We believe that separation of the positions of Chair and Chief Executive Officer reinforces the independence of the Board in its oversight of our business and affairs. In addition, we believe that having an independent Chair creates an environment that is more conducive to objective evaluation and oversight of management’s performance, increasing management accountability and improving the ability of our Board to monitor whether management’s actions are in our best interests and those of our stockholders. As a result, we believe that having an independent Chair can enhance the effectiveness of our Board as a whole. In addition, we have a separate chair for each committee of our Board. The chairs of each committee report to our Board at each quarterly Board meeting on the activities of their committees in fulfilling the responsibilities as detailed in the respective charters or advise of any shortcomings should that be the case.

Role of the Board in Risk Oversight

One of the Board’s key functions is informed oversight of our risk management process. Our Board does not have a standing risk management committee, but rather administers this oversight function directly through the Board as a whole, as well as through the standing committees that address risks inherent in their respective areas of oversight. In particular, our Board is responsible for monitoring and assessing strategic risk exposure, including a determination of the nature and level of risk appropriate for us. Our Audit Committee has the responsibility to consider and discuss our major financial risk exposures and the steps management has taken to monitor and control these exposures, including guidelines and policies to govern the process by which risk assessment and management is undertaken. Our Audit Committee also monitors compliance with certain legal and regulatory requirements, including requirements related to privacy and data protection, and oversees the performance of the internal audit function. Our Nominating and Corporate Governance Committee monitors the effectiveness of our corporate governance guidelines, including whether they are successful in preventing illegal or improper liability-creating conduct. Our Compensation Committee assesses and monitors whether any of our compensation policies and programs has the potential to encourage excessive risk-taking.

Management periodically reports to the Board or relevant committee, which provides guidance on risk assessment and mitigation. Each committee charged with risk oversight reports to the Board on risk matters.

Corporate Governance Guidelines

We have adopted Corporate Governance Guidelines to assure that the Board has the necessary authority and practices in place to review and evaluate our business operations as needed and to make decisions that are independent of our management. The guidelines are also intended to align the interests of directors and management with those of our stockholders. The Corporate Governance Guidelines set forth the practices the Board follows with respect to board composition and selection, board meetings and involvement of senior management, Chief Executive Officer performance evaluation and succession planning, and board committees and compensation. The Corporate Governance Guidelines, as well as the charters

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for each committee of the Board, may be viewed at https://www.sellaslifesciences.com/investors/corporate-governance/default.aspx#section=documents.

Clawback Policy

In March 2021, our Board adopted a clawback policy. The clawback policy applies to all incentive-based compensation granted after the policy’s adoption, including cash and equity incentive awards. The policy provides that if both (1) an accounting restatement is required due to our material noncompliance with any financial reporting requirement under the U.S. federal securities laws and (2) our Board (or a committee thereof), in its sole discretion, determines that an act or omission of a current or former executive officer contributed to the circumstances requiring the restatement and that such act or omission involved fraud or intentional misconduct then we will use reasonable efforts to recover from such person up to 100% of any incentive-based compensation awarded during the three-year period preceding the date on which we are required to prepare such accounting restatement. In light of the adoption by the SEC in October 2022 of new Rule 10D-1 under the Exchange Act implementing Section 954 of the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010, we amended and restated our clawback policy, effective September 12, 2023, in accordance with updated Nasdaq listing standards.

Committees of the Board of Directors and Meeting Attendance

Board of Directors. During the fiscal year ended December 31, 2025, our Board met eight times and took action by written consent one time. During 2025, each of our directors attended 100% of the regular meetings of the Board, and no director attended fewer than 75% of the total number of meetings of committees of our Board on which he or she served. Our Board makes every effort to but is not required to attend each annual meeting of our stockholders. All then-serving directors attended our annual meeting of stockholders held in 2025.

Committees of the Board of Directors. Our Board has three standing committees: an Audit Committee, a Compensation Committee, and a Nominating and Corporate Governance Committee. Each of the committees has authority to engage legal counsel or other experts or consultants, as it deems appropriate to carry out its responsibilities. Our Board has determined that each member of these committees meets the applicable Nasdaq rules and regulations regarding “independence” and each member is free of any relationship that would impair his or her individual exercise of independent judgment regarding the Company. Our Board also has a Science Committee, which is a standing committee that meets to review the Company’s clinical programs.

Name

Age

Position

Term
Expires

Audit
Committee

Compensation
Committee

Nominating
and
Corporate
Governance
Committee

Science
Committee

John Varian

Chair of the Board

2028

✔

Katherine Bach Kalin

Director

2027

✔*

✔

Angelos M. Stergiou

Director, President and
Chief Executive Officer

2028

✔

David A. Scheinberg

Director

2027

✔

✔*

Robert L. Van Nostrand

Director

2026

✔*

✔

Jane Wasman

Director

2026

✔

✔*

Denotes Chair of Committee

Audit Committee

The Audit Committee is currently comprised of three directors: Messrs. Van Nostrand, as chair, and Varian, and Ms. Wasman. The Audit Committee met four times in 2025. Our Board has adopted a written Audit Committee charter that is available to stockholders in the corporate governance section of our website

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at: https://ir.sellaslifesciences.com/corporate-governance/default.aspx. On March 19, 2024, we amended the charter of the Audit Committee to include the provision of oversight of the Company’s cybersecurity strategy, policies, and other initiatives.

The Audit Committee was established by our Board in accordance with Section 3(a)(58)(A) of the Exchange Act to oversee our corporate accounting and financial reporting processes and audits of our financial statements. The Audit Committee’s responsibilities include, among other things:

•

appointing our independent registered public accounting firm;

•

evaluating the qualifications, independence and performance of our independent registered public accountants;

•

reviewing and approving the audit and non-audit services to be performed by the independent registered public accountants and the compensation therefor;

•

reviewing the design, implementation, adequacy and effectiveness of our internal accounting controls and our critical accounting policies;

•

reviewing the design, implementation, adequacy and effectiveness of our internal controls regarding privacy and data protection and our related policies;

•

conferring with management and the independent registered public accountants regarding the effectiveness of internal control over financial reporting;

•

discussing with management and the independent registered public accounting firm the results of our annual audit and the review of our quarterly unaudited financial statements;

•

reviewing, overseeing and monitoring the integrity of our financial statements and our compliance with legal and regulatory requirements as they relate to financial statements or accounting matters;

•

reviewing and approving transactions between the Company and any related persons;

•

providing oversight of the Company’s cybersecurity risk management, strategy, and governance; and

•

reviewing and evaluating, at least annually, the performance of the Audit Committee and its members including compliance of the Audit Committee with its charter.

Our Board reviews the Nasdaq listing standards’ definition of “independence” for Audit Committee members on an annual basis and has determined that all members of our Audit Committee are independent (as currently defined in Rule 5605(c)(2)(A)(i) and (ii) of the Nasdaq listing standards and under Rule 10A-3 under the Exchange Act).

Our Board has also determined that Messrs. Varian and Van Nostrand each qualify as an “audit committee financial expert,” as defined in applicable SEC rules. Our Board made a qualitative assessment of the level of knowledge and experience of both Mr. Varian and Mr. Van Nostrand based on a number of factors, including the formal education and experience of each of Messrs. Van Nostrand and Varian as former chief financial officers for public reporting companies, and the status of Messrs. Van Nostrand and Varian as former Certified Public Accountants.

Compensation Committee

The Compensation Committee is currently comprised of three directors: Ms. Kalin, as chair, Dr. Scheinberg, and Mr. Varian. Each of Mr. Varian, Dr. Scheinberg and Ms. Kalin are independent (as independence is currently defined in Rule 5605(d)(2) of the Nasdaq listing standards). The Compensation Committee met four times and took action by written consent twice in 2025. Our Board has adopted a written Compensation Committee charter that is available to stockholders in the corporate governance section of our website at: https://ir.sellaslifesciences.com/corporate-governance/default.aspx.

The Compensation Committee acts on behalf of the Board to review, recommend for adoption and oversee our compensation strategy, policies, plans and programs, including:

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•

reviewing and recommending to the full Board for approval corporate performance goals and objectives relevant to the compensation of our executive officers, directors and other senior management and evaluation of performance in light of these stated goals and objectives;

•

engaging a compensation consultant to support the evaluation of long and short-term executive compensation, director compensation, and executive severance plans;

•

reviewing and recommending to the Board for approval of the compensation and other terms of employment or service, including severance and change-in-control arrangements, of our Chief Executive Officer and the other executive officers and directors;

•

reviewing and approving (or if it deems it appropriate, making recommendations to the full Board regarding) the equity incentive plans, compensation plans and similar programs advisable for us, as well as modifying, amending or terminating existing plans and programs;

•

evaluating risks associated with our compensation policies and practices and assessing whether risks arising from our compensation policies and practices for our employees are reasonably likely to have a material adverse effect on us;

•

reviewing and making recommendations to the full Board regarding the type and amount of compensation to be paid or awarded to our non-employee Board members;

•

establishing policies with respect to votes by our stockholders to approve executive compensation as required by Section 14A of the Exchange Act and determining our recommendations regarding the frequency of advisory votes on executive compensation, to the extent required by law;

•

reviewing and assessing the independence of compensation consultants, legal counsel and other advisors as required by Section 10C of the Exchange Act;

•

administering our equity incentive plans;

•

establishing policies with respect to equity compensation arrangements;

•

reviewing the competitiveness of our executive compensation programs and evaluating the effectiveness of our compensation policy and strategy in achieving expected benefits to us; and

•

reviewing and assessing on an annual basis the performance of the Compensation Committee and the Compensation Committee charter.

Each year, our Compensation Committee reviews with management our executive compensation tables and accompanying narrative disclosure and considers whether to recommend that it be included in proxy statements and other filings.

Compensation Committee Processes and Procedures

Typically, the Compensation Committee meets three times a year and with greater frequency if necessary. The agenda for each meeting is usually developed by the Chair of the Compensation Committee, in consultation with the Chief Executive Officer. The Compensation Committee meets regularly in executive session. From time to time, various members of management and other employees as well as outside advisors or consultants may be invited by the Compensation Committee to make presentations, to provide financial or other background information or advice or to otherwise participate in Compensation Committee meetings. The Chief Executive Officer may not participate in, or be present during, any deliberations or determinations of our Compensation Committee regarding his compensation or individual performance objectives. The charter of the Compensation Committee grants the Compensation Committee full access to all books, records, facilities and personnel of the Company. In addition, under the charter, the Compensation Committee has the authority to obtain, at the expense of the Company, advice and assistance from compensation consultants and internal and external legal, accounting or other advisors and other external resources that the Compensation Committee considers necessary or appropriate in the performance of its duties. The Compensation Committee has direct responsibility for the oversight of the work of any consultants or advisers engaged for the purpose of advising our Compensation Committee. In particular, the Compensation Committee has the authority to retain, in its sole discretion, compensation consultants to assist in its evaluation of executive and director compensation, including the authority to

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approve the consultant’s reasonable fees. Under the charter, the Compensation Committee may select, or receive advice from, a compensation consultant, legal counsel or other adviser to the Compensation Committee, other than in-house legal counsel and certain other types of advisers, only after taking into consideration six factors, prescribed by the SEC and Nasdaq, that bear upon the adviser’s independence; however, there is no requirement that any adviser be independent.

The Compensation Committee has engaged Radford, a division of Aon Hewitt, which is a subsidiary of Aon plc, as its compensation consultant. The Compensation Committee has assessed the independence of Radford pursuant to SEC rules and has concluded that Radford’s work for the Compensation Committee does not raise any conflict of interest. On an annual basis, Radford reviews our executive officer and director compensation relative to a peer group and against survey data available to Radford. Working with Radford, the Compensation Committee reviews and adjusts our peer group in the latter part of each year for upcoming end-of-year compensation decisions. Decisions regarding 2025 salaries and short-term non-equity incentive plan compensation were made by our Compensation Committee in early 2025 by reference to the peer group determined by our Compensation Committee in late 2024. In establishing the peer group of companies to be used for purposes of setting 2025 executive compensation, the Compensation Committee and Radford, using industry standard parameters for establishing a peer group, sought to identify companies that fit the following criteria:

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Publicly-traded, pre-commercial biopharma companies, with a focus on oncology;

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Phase 2 or Phase 3 stage of clinical development;

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Market capitalization at or below $250 million; and

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Fewer than 50 employees.

Based on these criteria, the Compensation Committee identified the following companies for our 2025 peer group: Actinium Pharmaceuticals, Inc., BeyondSpring Inc., Cardiff Oncology, Cellectar Biosciences, Inc., Checkpoint Therapeutics, Inc., Cidara Therapeutics, Inc., Compass Therapeutics, Corvus Pharmaceuticals, Inc., Cue Biopharma, Inc., Elevation Oncology, Inc., Equillium, Inc., Genelux Corporation, Immunic, Inc., Leap Therapeutics, Inc., PDS Biotechnology Corporation, Syros Pharmaceuticals, and Verastem, Inc.

Radford ultimately developed recommendations that were presented to the Compensation Committee for its consideration. Based on these recommendations, we determined our current compensation levels for our executive officers, including base salary and target bonus payments.

Nominating and Corporate Governance Committee

The Nominating and Corporate Governance Committee is responsible for identifying, reviewing and evaluating candidates to serve as directors of the Company (consistent with criteria approved by the Board), reviewing and evaluating incumbent directors, selecting candidates for election to our Board, making recommendations to our Board regarding the membership of the committees of the Board, and assessing the performance of management and our Board.

The Nominating and Corporate Governance Committee is currently comprised of three directors: Ms. Wasman, as chair, Ms. Kalin, and Mr. Van Nostrand. All members of our Nominating and Corporate Governance Committee are independent (as independence is currently defined in Rule 5605(a)(2) of the Nasdaq listing standards). The Nominating and Corporate Governance Committee met three times and took action by written consent one time in 2025. Our Board has adopted a written Nominating and Corporate Governance Committee charter that is available to stockholders in the corporate governance section of our website at: https://ir.sellaslifesciences.com/corporate-governance/default.aspx. The functions of this committee include, among other things:

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identifying, reviewing and evaluating candidates to serve on our Board consistent with criteria approved by our Board;

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evaluating director performance on the Board and applicable committees of the Board and determining whether continued service on our Board is appropriate;

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•

evaluating, nominating and recommending individuals for membership on our Board;

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evaluating nominations by stockholders of candidates for election to our Board;

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considering and assessing the independence of members of our Board;

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developing a set of corporate governance principles, periodically reviewing and assessing these principles and their application and recommending to our Board any changes to such policies and principles;

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considering questions of possible conflicts of interest of directors as such questions arise; and

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reviewing and assessing on an annual basis the performance of the Nominating and Corporate Governance Committee and the Nominating and Corporate Governance Committee charter.

On March 2, 2023, we amended the charter of the Nominating and Corporate Governance Committee to include the provision of oversight of the Company’s environmental, social and governance (“ESG”) strategy, policies and initiatives.

Our Nominating and Corporate Governance Committee believes that it is in the best position to identify, review, evaluate and select qualified candidates for Board membership, based on the comprehensive criteria for Board membership approved by the Board. Generally, our Nominating and Corporate Governance Committee will consider candidates recommended from several sources, such as other directors or officers, stockholders, third party search firms or other appropriate sources. Once identified, the Nominating and Corporate Governance Committee will evaluate a candidate’s qualifications. The Nominating and Corporate Governance Committee believes that candidates for director should have certain qualifications, including the ability to read and understand basic financial statements and the possession of the highest personal integrity and ethics. Candidates for director should also be over 21 years of age. Our Nominating and Corporate Governance Committee also considers such factors as possessing relevant expertise enabling the candidate to offer advice and guidance to management, having sufficient time to devote to the affairs of the Company, demonstrated excellence in his or her field, having the ability to exercise sound business judgment and having the commitment to rigorously represent the long-term interests of our stockholders. However, our Nominating and Corporate Governance Committee retains the right to modify these qualifications from time to time. Candidates for director nominees are reviewed in the context of the current composition of the Board, the operating requirements of the Company and the long-term interests of stockholders. In conducting this assessment, our Nominating and Corporate Governance Committee typically considers age, skills and such other factors as it deems appropriate, given our current needs and the needs of our Board, to maintain a balance of knowledge, experience and capability among its members in identifying and considering nominees for director, striving where appropriate to achieve a diverse balance of backgrounds, perspectives, experience, age, gender, ethnicity and country of citizenship on our Board of Directors and its committees. Our Nominating and Corporate Governance Committee also determines whether the nominee is independent for Nasdaq purposes, which determination is based upon applicable Nasdaq listing standards, applicable SEC rules and regulations and the advice of counsel, if necessary.

In the case of incumbent directors whose terms of office are set to expire, our Nominating and Corporate Governance Committee reviews these directors’ overall service to the Company during their terms, including the number of meetings attended, level of participation, quality of performance and any other relationships and transactions that might impair the directors’ independence. The Committee also takes into account the results of the Board’s self-evaluation, conducted annually on a group and individual basis.

Although the Nominating and Corporate Governance Committee does not have a formal policy with regard to the consideration of director candidates recommended by stockholders, it has the power and authority to consider recommendations for Board nominees and proposals submitted by the Company’s stockholders.

If a stockholder wishes to propose a candidate for consideration as a nominee for election to our Board, that stockholder must follow the procedures described in our Amended and Restated Bylaws. Any such recommendation should be made in writing on a timely basis as set forth in our Amended and Restated

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Bylaws to our Corporate Secretary at our principal office and should be accompanied by the following information concerning the proposed nominee:

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all information relating to such person that would be required to be disclosed in a proxy statement;

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certain biographical information about the proposed nominee;

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the class and number of shares of each class of capital stock of the corporation which are owned of record and beneficially by such proposed nominee; and

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the date or dates on which such shares were acquired and the investment intent of such acquisition.

The Company may require any proposed nominee to furnish such other information as it may reasonably require to determine the eligibility of such proposed nominee to serve as an independent director of the Company or that could be material to a reasonable stockholder’s understanding of the independence, or lack thereof, of such proposed nominee.

Science Committee

The Board has a Science Committee that meets at least quarterly to review the Company’s clinical programs and is currently comprised of Dr. Scheinberg, as Chair, and Dr. Stergiou and Mr. Varian, as members. The Science Committee met four times in 2025.

Report of the Audit Committee of the Board of Directors

The Audit Committee of the Board of SELLAS Life Sciences Group, Inc. consists of three members, each of whom the Board has determined meets the independence and experience requirements of the Nasdaq Capital Market and includes two “audit committee financial experts” within the meaning of the U.S. Securities and Exchange Commission’s rules.

In fulfilling its responsibilities for the financial statements for fiscal year December 31, 2025, the Audit Committee took the following actions:

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Reviewed and discussed the audited financial statements for the fiscal year ended December 31, 2025 with management and Baker Tilly US, LLP (“Baker Tilly”), our independent registered public accounting firm;

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Discussed with Baker Tilly the matters required to be discussed in accordance with Auditing Standard No. 1301- Communications with Audit committees; and

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Received written disclosures and the letter from Baker Tilly regarding its independence as required by applicable requirements of the Public Company Accounting Oversight Board regarding Baker Tilly’s communications with the Audit Committee and the Audit Committee further discussed with Baker Tilly their independence. The Audit Committee also considered taxation matters and other areas of oversight relating to the financial reporting and audit process that the committee determined appropriate.

Based on the Audit Committee’s review of the audited financial statements and discussions with management and Baker Tilly, the Audit Committee recommended to our Board, and the Board approved, that the audited financial statements be included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2025 for filing with the SEC.

Members of the Company’s Audit Committee: Messrs. Van Nostrand, as chair, and Varian, and Ms. Wasman.

Insider Trading Policy and Prohibition on Pledges

We have an Insider Trading Policy that, among other things, governs the buying and selling of our securities by all of our personnel, including directors, officers, employees and consultants and certain other covered persons. Our policy is designed to prevent violations of insider trading laws by our personnel and to avoid even the appearance of improper conduct in this regard by our personnel. The Insider Trading Policy prohibits covered persons from purchasing, selling, or otherwise disposing of our securities while in

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possession of material non-public information (except in limited circumstances, such as pursuant to a previously established trading plan). In addition, the Insider Trading Policy prohibits all employees, officers and directors from engaging in any transaction in which they may profit from short-term speculative swings in the value of our securities, including any of the following activities: (1) “short sales” (selling borrowed securities that the seller hopes can be purchased at a lower price in the future) of our securities; (2) use of our securities to secure a margin or other loan; (3) transactions in our securities involving hedging devices; (4) transactions in put or call options; and (5) other inherently speculative transactions with respect to our securities at any time. Our Insider Trading Policy also provides that no employee, officer or director may purchase Company securities on margin, borrow against Company securities held in a margin account, or pledge Company securities as collateral for a loan. However, an exception may be granted where a person wishes to pledge Company securities as collateral for a loan and clearly demonstrates the financial capacity to repay the loan without resorting to the pledged securities. The Insider Trading Policy includes quarterly and other trading blackouts and sets forth the procedures covered persons must follow before transacting in our securities, including pre-clearance by policy administrator of all transactions by officers, directors, certain members of management and certain other employees, as well as members of their households. A copy of the policy is filed as an exhibit to our Annual Report on Form 10-K for the year ended December 31, 2025 as filed with the SEC.

Stockholder Communications with the Board of Directors

The Board expects that the views of our stockholders pertinent to matters relating to our business will be heard by the Board, its committees, or individual directors, as applicable, and that appropriate responses be provided to stockholders on a timely basis. Stockholders wishing to formally communicate with the Board, any committee of the Board, the independent directors as a group or any individual director may send communications directly to us at SELLAS Life Sciences Group, Inc., Times Square Tower, 7 Times Square, Suite 2503, New York, New York 10036, Attention: Corporate Secretary. All clearly marked written communications, other than unsolicited advertising or promotional materials, are logged and copied, and forwarded, as may be warranted, to the director(s) to whom the communication was addressed. Undirected communications will be distributed to our entire Board, or to any individual director or directors as appropriate, depending on the facts and circumstances outlined in the communications. Please note that the foregoing communication procedure does not apply to (i) stockholder proposals pursuant to Exchange Act Rule 14a-8 and communications made in connection with such proposals or (ii) service of process or any other notice in a legal proceeding.

Stock Ownership Guidelines

On September 12, 2023, the Board approved the Company’s stock ownership guidelines (“Ownership Guidelines”) to encourage the Company’s directors and executive officers (“Covered Persons”) to maintain significant ownership interest in the Company, thereby helping to align their interests with those of our stockholders. The following are the Ownership Guidelines by Covered Persons:

	President and CEO			3 x annual base salary
	Other Executive Officers			1 x annual base salary
	Non-Employee Directors			3 x annual cash retainer

Covered Persons serving on the date of the initial adoption of these Ownership Guidelines are expected to achieve the applicable ownership levels by October 1, 2028. Newly hired and newly promoted executive officers and newly elected directors are expected to achieve the applicable levels within five years from the date of hire, promotion, or initial election. In the event of an increase in an executive officer’s annual base salary or a non-employee director’s annual cash retainer, such Covered Person will have two years from the time of the increase to acquire any additional shares to meet the Ownership Guidelines. Compliance will be determined as of October 1 of each year. In the event that a Covered Person does not satisfy the Ownership Guideline as of October 1, then the Covered Person is expected to thereafter retain all shares of common stock (vested or unvested) held by the Covered Person as of October 1, and at least 75% of the net after-tax shares of common stock thereafter acquired by the Covered Person (whether by option exercise, stock award, upon the vesting of RSUs or PSUs, through open market purchases or otherwise), until such

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time as the Covered Person satisfies the Ownership Guideline, measured as of any subsequent date on which the Covered Person wishes to dispose of shares of common stock. As of the date of this Proxy Statement, all of the Covered Persons, including all of our named executive officers, are making appropriate progress toward the Ownership Guidelines.

Code of Ethics

We have adopted a Code of Business Conduct and Ethics (the “Code”) which, along with our Amended and Restated Certificate of Incorporation, Amended and Restated Bylaws and the charters of our Board committees, provides a framework for the governance of our company. The Board’s Nominating and Corporate Governance Committee is responsible for periodically reviewing our governance practices and principles. The Code applies to all of our directors, officers and employees. Upon such periodic review in 2024, the Nominating and Corporate Governance Committee recommended to the Board amendments to the Code, including, among other things, clarification of examples of potential conflicts of interest, more clearly defining Company assets which are expected to be protected and efficiently used, and updating confidentiality obligations, which the Board approved on June 20, 2024.

The Code reflects current best practices and enhances our personnel’s understanding of our standards of ethical business practices, promotes awareness of ethical issues that may be encountered in carrying out an employee’s or director’s responsibilities, and provides clarity as to how to address ethical issues that may arise.

The foregoing description of the Code does not purport to be complete and is qualified in its entirety by reference to the full text of the Code, a copy of which is posted on our website at: https://ir.sellaslifesciences.com/corporate-governance/default.aspx. A printed copy may also be obtained by any stockholder upon request directed to SELLAS Life Sciences Group, Inc., Times Square Tower, 7 Times Square, Suite 2503, New York, NY 10036, Attention: Corporate Secretary. We also anticipate posting any future amendment or waiver of the Code on our website within four business days of the date of such amendment or waiver. The contents of our website are not incorporated by reference in this report or made a part hereof for any purpose.

Executive Officers

The names and ages of our current executive officers and their positions are as follows:

Name	Age	Position with the Company
Angelos M. Stergiou, M.D., Sc.D. h.c.	50	President, Chief Executive Officer and Director
John T. Burns	41	Senior Vice President, Chief Financial Officer
Dragan Cicic, M.D.	62	Senior Vice President, Chief Development Officer

Biographical Information Regarding Executive Officers

Set forth below is a biographical description of each executive officer based on information supplied by such executive officer:

Angelos M. Stergiou, M.D., Sc.D. h.c., see “Board of Directors.”

John T. Burns. Mr. Burns has served as the Company’s Senior Vice President, Chief Financial Officer since February 2023. Mr. Burns previously served as the Company’s Vice President, Finance, and Corporate Controller from December 2017 to December 2020, as Vice President, Finance, Corporate Controller and Principal Accounting Officer from January 2021 to December 2021 and as Senior Vice President, Finance, and Chief Accounting Officer from January 2022 to January 2023. Mr. Burns has over 15 years of experience in finance and accounting. Mr. Burns joined the Company in May 2013 and has held various positions of increasing responsibility during his tenure. Prior to joining the Company, Mr. Burns was a Securities and Exchange Reporting Manager at Pixelworks, Inc. (NASDAQ: PXLW), and began his career in public accounting at Moss Adams LLP, predecessor of Baker Tilly US, LLP. Burns received a B.S.M. in Finance and Master of Accounting degree from Tulane University. He is an active Certified Public Accountant.

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Dragan Cicic, M.D. Dr. Cicic has served as the Company’s Senior Vice President, Chief Development Officer since January 2024. Dr. Cicic previously served as the Company’s Senior Vice President, Clinical Research & Development from February 2020 to December 2023. Dr. Cicic has over 20 years of experience in the biopharmaceutical industry. Before joining SELLAS, he was Senior Vice President, Clinical Lead, at Klus Pharma, a wholly owned U.S. subsidiary of Kelun, a major China-based multinational pharmaceutical company. At Klus Pharma, Dr. Cicic led the global clinical development of targeted solid cancer biologicals and was involved in the development of novel checkpoint inhibitors as well as other innovative biological and small molecule drug candidates. Prior to Klus Pharma, Dr. Cicic held senior management positions at Actinium Pharmaceuticals, where he launched key clinical trials, both early and late stage, in hematologic malignancies, primarily in acute myeloid leukemia. Dr. Cicic also worked with QED Technologies, a consulting company focused on life sciences. He received his medical degree from the University of Belgrade and an MBA from the Wharton School of the University of Pennsylvania. Dr. Cicic also did a Fellowship at Harvard University. Dr. Cicic has published extensively in the fields of hematologic malignancies and solid cancers.

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EXECUTIVE OFFICER AND DIRECTOR COMPENSATION

Summary Compensation Table

The following table shows the compensation paid or accrued to our named executive officers (“NEOs”) for 2025 during the last two fiscal years ended December 31, 2025 and 2024. The NEOs are (i) our President and Chief Executive Officer, Angelos M. Stergiou, M.D., Sc.D. h.c., and (ii) our other two most highly compensated executive officers earning more than $100,000 who were serving as executive officers at the end of the year ended December 31, 2025.

Name	Year		Salary ($)		Non-Equity Incentive Plan Compensation ($)(1)		Bonus ($)		Option Awards ($)(2)		Stock Awards ($)(3)		All Other Compensation ($)		Total ($)
Angelos M. Stergiou, M.D., Sc.D. h.c. President and Chief Executive Officer		2025		676,000		390,390		—		327,695		477,107		6,618(5)		1,877,810
		2024		650,000		339,625		—		112,787		82,601		4,760(5)		1,189,773
Dragan Cicic, M. D. Senior Vice President, Chief Development Officer		2025		451,234		193,128		—		143,990		185,071		18,372(6)		991,795
		2024		427,710		164,240		50,000(4)		30,739		23,378		17,414(7)		713,480
John T. Burns Senior Vice President, Chief Financial Officer		2025		429,605		185,589		—		143,990		185,071		15,398(6)		959,653
		2024		401,500		154,176		50,000(4)		35,468		24,417		15,218(7)		680,778

(1)

For additional information regarding the non-equity incentive plan short-term compensation, see the section entitled “Non-Equity Incentive Plan Short Term Compensation.”

(2)

The amounts reflected in this column represent the aggregate grant date fair value computed in accordance with ASC Topic 718. To determine the value of stock option awards, we use a Black Scholes pricing model to value stock options at the time of their grant. This model requires us to estimate the future value of our stock price based in part on the historic price volatility of our stock. See Note 10 to our consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, “Consolidated Financial Statements — Notes to Consolidated Financial Statements — Stock-Based Compensation,” for details as to the assumptions used to determine the fair value of equity awards.

(3)

The amounts reflected in this column represent the aggregate grant date fair value of restricted stock units computed in accordance with ASC Topic 718. The grant date fair value of restricted stock units is based on the closing price of our common stock on the date of grant.

(4)

Represents an additional bonus award.

(5)

Represents the following Company benefits paid on behalf of the employee: medical, dental, vision, short-term/long-term liability insurances, education, basic life insurance, personal accident insurance, workers’ compensation insurance and employer liability insurance.

(6)

Represents 401(k) Plan matching contributions by the Company of $14,000 and benefits paid on behalf of the employee: medical, dental, vision, short-term/long-term liability insurances, education, basic life insurance, personal accident insurance, workers’ compensation insurance and employer liability insurance.

(7)

Represents 401(k) Plan matching contributions by the Company of $13,820 and benefits paid on behalf of the employee: medical, dental, vision, short-term/long-term liability insurances, education, basic life insurance, personal accident insurance, workers’ compensation insurance and employer liability insurance.

Narrative Disclosure to Summary Compensation Table

Elements of Compensation

In addition to each officer’s base salary, our executive officer compensation program consists of a cash incentive bonus plan and discretionary stock option awards in addition to customary benefits. The amounts

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of compensation awarded for each element of the Company’s compensation program (i.e., base salary, bonuses and stock options) are reviewed in connection with the Company’s performance.

Base Salary

Annual base salaries compensate our executive officers for fulfilling the requirements of their respective positions and provide them with a level of cash income predictability and stability with respect to a portion of their total compensation. We believe that the level of an executive officer’s base salary should reflect the executive’s performance, experience and breadth of responsibilities, our understanding of salaries for similar positions within our industry and any other factors relevant to that particular job.

Base salaries are typically negotiated at the outset of an executive’s employment in connection with an offer of employment and employment agreement. Salary levels are considered annually as part of our performance review process, but also in cases including promotion or other changes in the job responsibilities of an executive officer. Merit and Company-wide general increases are also taken into consideration when determining increases to base salary.

Non-Equity Incentive Plan Short Term Compensation

For 2024 and 2025, short-term incentive cash compensation for our executive officers was determined based on the achievement of performance metrics related to our corporate goals. The corporate goals are proposed by senior management and reviewed and approved by our Compensation Committee and our Board on an annual basis at the start of each year. Our annual corporate goals are typically focused on the achievement of specified clinical development goals with a focus on advancing our clinical pipeline. The annual goals also usually include the pursuit of certain corporate development goals, such as business development initiatives and achievement of cash management strategies in order to assure adequate funding for our clinical development programs. The goals are designed to require significant effort in order to achieve our clinical development and operational goals while also being achievable with the requisite hard work and dedication. Awards made under our short-term cash incentive program utilize a pay-for-performance strategy and award our NEOs for the level of achievement of specified annual corporate goals, as well as individual goals for our NEOs other than our CEO whose short-term incentive compensation is based 100% on the level of achievement of our corporate goals.

Equity Grants

In January 2025, the Compensation Committee recommended, and our Board approved, the grant of 385,750, 169,500, and 169,500 options to Dr. Stergiou, Mr. Burns, and Dr. Cicic, respectively, at an exercise price of $0.9525 per share, which was the fair market value on the grant date. One quarter of the shares subject to these options vested in January 2026 and the remaining shares subject to the options will vest and become exercisable in equal monthly installments for 36 months thereafter. In January 2025, the Compensation Committee also recommended, and our Board approved, the grant of 257,000, 113,000, and 113,000 restricted stock units to Dr. Stergiou, Mr. Burns, and Dr. Cicic, respectively (the “2025 RSUs”). The 2025 RSUs vest 25% each December 1, commencing December 1, 2025, until fully vested, provided that the NEO remains in service with the Company through each such vesting date. Additionally, in January 2025, the Compensation Committee also recommended, and our Board approved, the grant of 243,900, 81,300, and 81,300 restricted stock units to Dr. Stergiou, Mr. Burns, and Dr. Cicic, respectively (the “2025 Additional RSUs”). The 2025 Additional RSUs vested in full on December 1, 2025.

In January 2024, the Compensation Committee recommended, and our Board approved, the grant of 238,500, 75,000, and 65,000 options to Dr. Stergiou, Mr. Burns, and Dr. Cicic, respectively, at an exercise price of $0.5195 per share, which was the fair market value on the grant date. One quarter of the shares subject to these options vested in January 2025 and the remaining shares subject to the options will vest and become exercisable in equal monthly installments for 36 months thereafter. In January 2024, the Compensation Committee also recommended, and our Board approved, the grant of 159,000, 47,000, and 45,000 restricted stock units to Dr. Stergiou, Mr. Burns, and Dr. Cicic, respectively (the “2024 RSUs”). The 2024 RSUs vest 25% each December 1, commencing December 1, 2024, until fully vested, provided that the NEO remains in service with the Company through each such vesting date.

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Employment Agreements

We have entered into employment agreements with each of the named executive officers described below, which include standard confidential information and/or inventions assignment agreements, and under which each of the named executive officers has agreed not to disclose our confidential information. The named executive officers are each eligible to participate in, subject to applicable eligibility requirements, all of our employee retirement and welfare benefit plans and programs made available to senior level executives. All severance benefits payable to the named executive officers under their employment agreements are subject to their signing, not revoking and complying with a release of claims in favor of us and are subject to applicable taxes and withholding.

Angelos M. Stergiou, M.D., Sc.D. h.c.

The 2019 Stergiou Agreement became effective as of July 1, 2019, at which time it replaced and superseded the 2016 Stergiou Agreement. The 2019 Stergiou Agreement has an initial two-year term unless terminated prior thereto (i) by us with cause (at any time) or without cause (upon at least 30 days’ prior written notice), or (ii) by Dr. Stergiou for good reason (upon at least 90 days prior written notice of the reason with a cure period of 30 days for us to correct the act or failure to act that constitutes good reason), or without good reason (upon at least 90 days prior written notice) or (iii) due to Dr. Stergiou’s death or disability. The 2019 Stergiou Agreement shall continue until terminated in accordance with its terms.

Pursuant to the terms of the 2019 Stergiou Agreement, Dr. Stergiou is entitled to an annual base salary of $525,000 (subject to review and adjustment in the sole discretion of the Board or the compensation committee thereof) and a discretionary annual cash bonus, with a target amount no less than 50% of Dr. Stergiou’s then effective base salary (subject to continued employment and the achievement of certain performance objectives established by the Board or Compensation Committee of the Board). The agreement also provides that to the extent that any benefit distributable pursuant to the terms of the agreement would be subject to the excise tax imposed under Section 4999 of the Internal Revenue Code of 1986, as amended (the “IRC”) , then the total payments payable to Dr. Stergiou will be reduced as set forth in the agreement (but not below zero) so that the maximum amount of such payments (after the reduction) shall be one dollar ($1.00) less than the amount which would cause such payments to be subject to the excise tax.

In addition, Dr. Stergiou is eligible to receive equity awards in the sole discretion of the Board or the Compensation Committee.

John T. Burns

Effective December 30, 2017, we entered into an employment agreement with Mr. Burns. Under this agreement, Mr. Burns is entitled to an annual base salary of $235,000 (subject to review and adjustment in the discretion of Company’s management team, the Board, or the Compensation Committee) and a discretionary annual cash bonus, with a target amount of up to 30% of Mr. Burns’ then-effective base salary. In connection with Mr. Burns’ appointment as Chief Financial Officer on February 2, 2023, Mr. Burns’ base salary was increased to $365,000 per year, and his annual target bonus was increased to 40% of his base salary.

Pursuant to the terms of his employment agreement, Mr. Burns is eligible to purchase stock options pursuant to and in accordance with the terms and conditions of a stock incentive plan upon adoption of said stock incentive plan by us and the Board. In addition, Mr. Burns is eligible to participate in any employee benefit plans of the Company of general applicability to other of our employees including, without limitation, group medical, dental, vision, disability, life insurance, and flexible spending account plans.

Mr. Burns’ employment agreement does not have a specified term and may be terminated (i) by us with or without cause at any time or (ii) by Mr. Burns with or without cause upon at least 45 days’ prior written notice. In December 2021, we entered into a severance agreement with Mr. Burns (the “Burns Severance Agreement”) pursuant to which Mr. Burns is entitled to receive additional compensation in the event that Mr. Burns’ employment is terminated under certain conditions. In March 2025, we amended the Burns Severance Agreement (the “Burns Amended Severance Agreement”). See the discussion below under “Potential Payments Upon Termination or Change of Control.” In addition to the payment of severance

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amounts, the Burns Severance Agreement also provides that to the extent that any benefit distributable pursuant to the terms of the Burns Severance Agreement would be subject to the excise tax imposed under Section 4999 of the IRC, then the total payments payable to Mr. Burns shall be reduced as set forth in the Burns Severance Agreement (but not below zero) so that the maximum amount of such payments (after the reduction) shall be one dollar ($1.00) less than the amount which would cause such payments to be subject to the excise tax.

Dragan Cicic, M.D.

Effective February 3, 2020, we entered into an employment agreement with Dr. Cicic. Under this agreement, Dr. Cicic was entitled to an annual base salary of $330,000 (subject to review and adjustment in the discretion of the Compensation Committee) and a discretionary annual cash bonus, with a target amount of up to 30% of Dr. Cicic’s then-effective base salary (subject to continued employment and the achievement of certain performance objectives established by our Board or Compensation Committee).

Pursuant to the terms of his employment agreement, Dr. Cicic is eligible to purchase stock options pursuant to and in accordance with the terms and conditions of a stock incentive plan upon adoption of said stock incentive plan by us and the Board. In addition, Dr. Cicic is eligible to participate in any employee benefit plans of the Company of general applicability to other of our employees including, without limitation, group medical, dental, vision, disability, life insurance, and flexible spending account plans.

Dr. Cicic’s employment agreement did not have a specified term and either party was permitted to terminate Dr. Cicic’s employment agreement by providing written notice at any time, with or without cause. In January 2024, we entered into a severance agreement with Dr. Cicic (the “Cicic Severance Agreement”) pursuant to which Dr. Cicic is entitled to receive additional compensation in the event that Dr. Cicic’s employment is terminated under certain conditions. In March 2025, we amended the Cicic Severance Agreement (the “Cicic Amended Severance Agreement”). See the discussion below under “Potential Payments Upon Termination or Change of Control.” In addition to the payment of severance amounts, the Cicic Severance Agreement also provides that to the extent that any benefit distributable pursuant to the terms of the Cicic Severance Agreement would be subject to the excise tax imposed under Section 4999 of the IRC, then the total payments payable to Dr. Cicic shall be reduced as set forth in the Cicic Severance Agreement (but not below zero) so that the maximum amount of such payments (after the reduction) shall be one dollar ($1.00) less than the amount which would cause such payments to be subject to the excise tax.

Potential Payments Upon Termination or Change of Control

Angelos M. Stergiou

Potential Payments Made Upon Termination with Cause or Without Good Reason. The 2019 Stergiou Agreement provides that if Dr. Stergiou’s employment is terminated with cause by us, or by Dr. Stergiou without good reason, we will pay Dr. Stergiou all his accrued benefits, and all other rights and benefits of Dr. Stergiou will terminate upon such termination, except for any right to the continuation of benefits otherwise provided by law.

Potential Payments Made Upon Termination Without Cause or for Good Reason. The 2019 Stergiou Agreement provides that if we terminate Dr. Stergiou’s employment without cause or Dr. Stergiou resigns for good reason, we will pay Dr. Stergiou the following amounts in equal installments over a defined 12 month period: (i) an amount equal to 18 months of his then-current base salary, less standard employment-related withholdings and deductions and (ii) an amount equal to a pro-rated portion of his annual short-term incentive compensation for the year in which his employment terminates, without regard to whether the performance goals with respect to such bonus have been established or met and less standard employment-related withholdings and deductions. In addition, Dr. Stergiou will be entitled, if he so elects, to receive reimbursement for Consolidated Omnibus Budget Reconciliation Act of 1986 (“COBRA”) monthly premiums for a specified period of time.

Potential Payments Upon Termination Related to Change in Control. The 2019 Stergiou Agreement provides that if we terminate Dr. Stergiou’s employment without cause or he resigns for good reason within a one month period prior to or one year following a change in control we will pay him the following

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amounts in equal installments over a 12 month period: (i) an amount equal to 24 months of his then-current base salary, less standard employment-related withholdings and deductions; and (ii) an amount equal to one and one-half times his target bonus for the year in which his employment terminates, without regard to whether the performance goals with respect to such target bonus have been established or met and less standard employment-related withholdings and deductions. In addition, Dr. Stergiou will be entitled, if he so elects, to receive reimbursement for COBRA monthly premiums for a specified period of time. Furthermore, the vesting of all of his equity awards will immediately vest in full and become exercisable as of the date of termination.

John T. Burns

Potential Payments Made Upon Termination with Cause or Without Good Reason. Pursuant to the terms of the Burns Employment Agreement, commencing on the 18-month anniversary of the effective date of the Burns Employment Agreement, in the event that Mr. Burns’ employment is terminated by us without cause or by Mr. Burns for good reason, we will pay Mr. Burns an amount equal to nine months of his then-current base salary, less standard employment-related withholdings and deductions.

Potential Payments Upon Termination Related to Change in Control. The Burns Severance Agreement provided that if we terminate Mr. Burns’ employment without cause or he resigns for good reason within one year following a change in control, we would pay him the following amounts in equal installments over a 12 month period: (i) an amount equal to 12 months of his then-current base salary, less standard employment-related withholdings and deductions; and (ii) an amount equal to his target bonus for the year in which his employment terminates, without regard to whether the performance goals with respect to such target bonus have been established or met and less standard employment-related with holdings and deductions. In addition, Mr. Burns will be entitled, if he so elects, to receive reimbursement for COBRA monthly premiums for a specified period of time. Under the Burns Amended Severance Agreement, the equal installments over a 12 month period has been amended to a 15 month period, and the amount equal to 12 months of his then-current base salary (less standard employment-related withholdings and deductions), has been amended to the amount equal to 15 months of his then-current base salary (less standard employment-related withholdings).

Dragan Cicic, M.D.

Potential Payments Made Upon Termination with Cause or Without Good Reason. Pursuant to the terms of the Cicic Employment Agreement, in the event that Dr. Cicic’s employment is terminated by us without cause or by Dr. Cicic for good reason, we will pay Dr. Cicic an amount equal to nine months of his then-current base salary, less standard employment-related withholdings and deductions, and (ii) an amount equal to a pro-rated portion of Dr. Cicic’s annual short-term incentive compensation. In addition, Dr. Cicic will be entitled, if he so elects, to receive reimbursement for COBRA monthly premiums for a specified period of time.

Potential Payments Upon Termination Related to Change in Control. The Cicic Severance Agreement provides that if we terminate Dr. Cicic’s employment without cause or he resigns for good reason within one year following a change in control, we will pay him the following amounts in equal installments over a 12 month period: (i) an amount equal to 12 months of his then-current base salary, less standard employment-related withholdings and deductions; and (ii) an amount equal to his target bonus for the year in which his employment terminates, without regard to whether the performance goals with respect to such target bonus have been established or met and less standard employment-related with holdings and deductions. In addition, Dr. Cicic will be entitled, if he so elects, to receive reimbursement for COBRA monthly premiums for a specified period of time. Under the Cicic Amended Severance Agreement, the equal installments over a 12 month period has been amended to a 15 month period, and the amount equal to 12 months of his then-current base salary (less standard employment-related withholdings and deductions) has been amended to the amount equal to 15 months of his then-current base salary (less standard employment-related withholdings).

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Outstanding Equity Awards At 2025 Fiscal Year-End

The following table discloses certain information regarding all outstanding equity awards at fiscal year-end for each of the officers named in the Summary Compensation Table.

Name	Grant Date		Number of Securities Underlying Unexercised Options Exercisable		Number of Securities Underlying Unexercised Options (#) Unexercisable(1)		Option Exercise Price ($)(2)			Option Expiration Date		Number of Shares or Units of Stock That Have Not Vested (#)(3)		Market Value of Shares or Units of Stock That Have Not Vested ($)(4)
Angelos M. Stergiou		03/13/2018		1,900		—		$	262.00		03/13/2028		—			—
		03/18/2019		8,500		—		$	69.00		03/18/2029		—			—
		03/12/2020		70,000		—		$	1.89		03/12/2030		—			—
		03/12/2020		—		—			—		—		95,000		$	358,150
		03/04/2021		118,500		—		$	8.00		03/04/2031		—			—
		01/31/2022		161,563		3,438		$	5.34		01/31/2032		—			—
		01/31/2022		—		—			—		—		—			—
		02/02/2023		154,063		63,438		$	3.34		02/02/2033		—			—
		02/02/2023		—		—			—		—		14,500		$	54,665
		01/02/2024		114,281		124,219		$	0.5195		01/22/2034		—			—
		01/22/2024		—		—			—		—		79,500		$	299,715
		01/10/2025		—		385,750		$	0.9525		01/10/2035		—			—
		01/10/2025		—		—			—		—		192,750		$	726,668
Dragan Cicic		03/12/2020		35,000		—		$	1.89		03/12/2030		—			—
		03/12/2020		—		—			—		—		25,000		$	94,250
		03/04/2021		47,250		—		$	8.00		03/04/2031		—			—
		01/31/2022		47,734		1,016		$	5.34		01/31/2032		—			—
		01/31/2022		—		—			—		—		—			—
		02/02/2023		38,958		16,042		$	3.34		02/02/2033		—			—
		02/02/2023		—		—			—		—		4,000		$	15,080
		01/22/2024		31,146		33,854		$	0.5195		01/22/2034		—			—
		01/22/2024		—		—			—		—		22,500		$	84,825
		01/10/2025		—		169,500		$	0.9525		01/10/2035		—			—
		01/10/2025		—		—			—		—		84,750		$	319,508
John T. Burns		03/13/2018		400		—		$	262.00		03/13/2028		—			—
		03/18/2019		1,800		—		$	69.00		03/18/2029		—			—
		03/12/2020		10,000		—		$	1.89		03/12/2030		—			—
		03/12/2020		—		—			—		—		15,000		$	56,550
		03/04/2021		17,250		—		$	8.00		03/04/2031		—			—
		01/31/2022		35,250		750		$	5.34		01/31/2032		—			—
		01/31/2022		—		—			—		—		—			—
		02/02/2023		53,125		21,875		$	3.34		02/02/2033		—			—
		02/02/2023		—		—			—		—		5,000		$	18,850
		01/22/2024		35,938		39,063		$	0.5195		01/22/2034		—			—
		01/22/2024		—		—			—		—		23,500		$	88,595
		01/10/2025		—		169,500		$	0.9525		01/10/2035		—			—
		01/10/2025		—		—			—		—		84,750		$	319,508

(1)

These unvested shares underlying each option grant are scheduled to vest at a rate of one quarter on the first anniversary of the grant date and with the remainder over 36 equal monthly installments.

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(2)

The exercise price was determined by using the market price for our common stock at the close of business on the grant date.

(3)

The March 2020 RSUs are scheduled to vest as follows: (i) 50% on meeting the primary endpoint in our Phase 3 REGAL study for GPS and (ii) 50% upon approval by the FDA of a BLA for GPS. The March 2021 RSUs, the January 2022 RSUs, the February 2023 RSUs, the January 2024 RSUs, and the January 2025 RSUs vest 25% on each December 1, commencing in the year of grant, until fully vested, provided that the Reporting Person remains in service with the Company through each such vesting date.

(4)

Each RSU entitles the holder thereof to receive one share of our common stock for each RSU granted upon vesting or settlement. The market value is calculated by multiplying $3.77, the closing price of a share of our common stock on December 31, 2025, the last trading day of the year, as reported on Nasdaq, by the number of unvested units.

Pay versus Performance

As required by SEC rules, we are providing the following information about the relationship between executive compensation actually paid and our financial performance.

Year(a)	Summary Compensation Table Total for PEO(b)			Compensation Actually Paid to PEO(c)			Average Summary Compensation Table Total for Non-PEO NEOs(d)			Average Compensation Actually Paid to Non-PEO NEOs(e)			Value of Initial Fixed $100 Investment Based On Total Shareholder Return(f)			Net Loss (thousands)(g)
2025		$	1,877,810		$	4,426,030		$	975,724		$	1,963,473		$	159.75		$	(26,863)
2024		$	1,189,773		$	1,333,403		$	697,129		$	734,057		$	44.07		$	(30,881)
2023		$	1,752,638		$	801,284		$	855,814		$	536,561		$	44.92		$	(37,340)

(a)

Dr. Stergiou served as our Principal Executive Officer (“PEO”) in all years presented. For 2024, Mr. Burns and Dr. Cicic served as our other NEOs. For 2023, our General Counsel at the time and Mr. Burns served as our other NEOs.

(b)

The dollar amounts reported in column (b) represent the amount of total compensation reported for Dr. Stergiou (our PEO) for each corresponding year in the “Total” column of the Summary Compensation Table.

(c)

The dollar amounts reported in column (c) represent the amount of “compensation actually paid” to Dr. Stergiou. The amounts are computed in accordance with SEC rules by deducting and adding the following amounts from the “Total” column of the Summary Compensation Table (pursuant to SEC rules, fair value at each measurement date is computed in a manner consistent with the fair value methodology used to account for share-based payments in our financial statements under GAAP). The dollar amounts do not reflect the actual amount of compensation earned by or paid to Dr. Stergiou during the applicable year.

Year	Reported Summary Comp Table Total for PEO			Reported Value of Equity Awards(1)			Equity Award Adjustments(2)			Compensation Actually Paid to PEO
2025		$	1,877,810		$	(804,802)		$	3,353,022		$	4,426,030
2024		$	1,189,773		$	(195,388)		$	339,018		$	1,333,403
2023		$	1,752,638		$	(848,395)		$	(102,959)		$	801,284

(1)

The dollar amounts reported are the total value of equity awards for Dr. Stergiou for each corresponding year in the “Option Awards” and “Stock Awards” columns of the Summary Compensation Table.

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(2)

The amounts deducted or added in calculating the equity award adjustments are as follows:

Year	Year End Fair Value of Outstanding and Unvested Equity Awards Granted in the Year			Year over Year Change in Fair Value of Outstanding and Unvested Equity Awards Granted in Prior Years			Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year			Year over Year Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year			Total Equity Award Adjustments
2025		$	2,083,854		$	709,059		$	462,225		$	97,884		$	3,353,022
2024		$	343,659		$	(27,979)		$	44,918		$	(21,580)		$	339,018
2023		$	238,628		$	(315,187)		$	15,660		$	(42,060)		$	(102,959)

(d)

The dollar amounts reported in column (d) represent the average of the amounts reported for the Company’s non-PEO NEOs for each corresponding year in the “Total” column of the Summary Compensation table.

(e)

The dollar amounts reported in column (e) represent the average amount of “compensation actually paid” to the Company’s non-PEO NEOs, as computed in accordance with SEC rules by deducting and adding the following amounts from the “Total” column of the Summary Compensation Table using the same methodology described above in Note (c)2. The dollar amounts do not reflect the actual average amount of compensation earned by or paid to the Company’s non-PEO NEOs during the applicable year.

Year	Average Reported Summary Compensation Table Total for Non-PEO NEOs			Average Reported Value of Equity Awards(1)			Average Equity Award Adjustments(2)			Average Compensation Actually Paid to Non-PEO NEOs
2025		$	975,724		$	(329,061)		$	1,316,810		$	1,963,473
2024		$	697,129		$	(57,000)		$	93,928		$	734,057
2023		$	855,814		$	(300,075)		$	(19,178)		$	536,561

(1)

The dollar amounts reported are the total value of equity awards for the non-PEO NEOs for each corresponding year in the “Option Awards” and “Stock Awards” columns of the Summary Compensation Table.

(2)

The amounts added (or deducted, if applicable) in calculating the total average equity award adjustments in each applicable year are as follows:

Year	Average Year End Fair Value of Outstanding and Unvested Equity Awards Granted in the Year			Year over Year Average Change in Fair Value of Outstanding and Unvested Equity Awards Granted in Prior Years			Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year			Year over Year Average Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year			Total Average Equity Award Adjustments
2025		$	915,860		$	208,374		$	164,325		$	28,251		$	1,316,810
2024		$	100,344		$	(7,840)		$	7,751		$	(6,327)		$	93,928
2023		$	69,008		$	(82,509)		$	5,400		$	(11,077)		$	(19,178)

(f)

Cumulative Total Shareholder Return (“TSR”) measures the cumulative value of $100 invested on the last trading day before the earliest fiscal year in the table, or December 31, 2022, including the reinvestment of dividends, through and including the end of the applicable fiscal year for which TSR is calculated, or December 31, 2023, 2024, and 2025. We did not pay dividends in the periods presented.

(g)

The dollar amounts reported represent the amount of net loss reflected in the Company’s audited financial statements for the applicable year.

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Relationship between Compensation Actually Paid and the Company’s Net Loss and Total Shareholder Return

As described in more detail in the section “Narrative Disclosure to Summary Compensation Table,” the Company’s executive compensation program reflects a variable pay-for-performance philosophy. Because we are not a commercial-stage company, we did not have any revenue during the periods presented, other than milestone-based licensing revenue in the reported years. Consequently, the Company has not historically looked to net income (loss) as a performance measure for our executive compensation program. Moreover, the Company generally seeks to incentivize long-term performance, and therefore does not specifically align the Company’s performance measures with compensation that is actually paid (as computed in accordance with SEC rules) for a particular year. A large component of our executive compensation is equity-based to align compensation with performance, but compensation also includes other appropriate incentives such as cash bonuses that are designed to incentivize our executives to achieve annual corporate goals. In accordance with SEC rules, the Company is providing the following descriptions of the relationships between information presented in the Pay versus Performance table above.

The graph below compares the amount of compensation actually paid to Dr. Stergiou and the average amount of compensation actually paid to the Company’s non-PEO NEOs with the Company’s net loss for the past three years.

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Director Compensation

The following table shows the total compensation paid or accrued during the fiscal year ended December 31, 2025 to each of our non-employee directors. Directors who are employed by us are not compensated for their service on our Board.

Name	Fees Earned or Paid in Cash ($)(1)		Option Awards ($)(2)		Stock Awards ($)(3)		Total ($)(4)
John Varian		94,000		15,011		11,906		120,917
Robert L. Van Nostrand		66,000		15,011		11,906		92,917
Jane Wasman		66,000		15,011		11,906		92,917
David A. Scheinberg		66,000		15,011		11,906		92,917
Katherine Bach Kalin		66,000		15,011		11,906		92,917

(1)

Represents cash compensation earned or paid for services rendered by each non-employee director for services on our Board or a committee thereof.

(2)

Amounts shown reflect the grant date fair value computed in accordance with FASB ASC 718. Each director received 18,500 stock options on January 10, 2025. The assumptions we used in valuing options are described more fully in “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and in the footnotes to our financial statements incorporated in the Annual Report on Form 10-K for the fiscal year ended December 31, 2025.

(3)

(4)

Dr. Angelos M. Stergiou, our Chief Executive Officer, is also a member of our Board, but does not receive any additional compensation for his service as a director.

Director Compensation Policy

Non-Employee Director Compensation Policy

Upon the recommendation of the Compensation Committee, the Board adopted a formal Non-Employee Director Compensation Policy, effective as of March 2, 2023.

The Non-Employee Director Compensation Policy provides for the following compensation for our directors:

Compensation Category	Amount
Annual Base Compensation		$	40,000
Additional Non-Executive Chair Compensation		$	30,000
Additional Committee Chair Compensation:
Audit		$	18,000
Compensation		$	18,000
Nominating and Corporate Governance		$	18,000
Science		$	18,000

SEC Form DEF 14A filed by SELLAS Life Sciences Group Inc.