DEF 14A

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

(Amendment No. )

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 under §240.14a-12

BOUNDLESS BIO, 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 all boxes that apply):


☒	No fee required


☐	Fee paid previously 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

Boundless Bio, Inc.

10955 Alexandria Way, Suite 100

San Diego, CA 92121

Notice of Annual Meeting of Stockholders

To be held on June 23, 2025

Dear Stockholder:

Notice is hereby given that the 2025 Annual Meeting of Stockholders of Boundless Bio, Inc., a Delaware corporation, will be held on Monday, June 23, 2025 at 8:00 a.m. Pacific Time for the following purposes, as more fully described in the accompanying proxy statement:

to elect Christine Brennan, Ph.D. and Nancy Whiting, Pharm.D. as Class I directors to hold office until our 2028 annual meeting of stockholders;

to ratify the appointment of KPMG LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2025; and

to transact any other business properly brought before the meeting.

The record date for the meeting is April 25, 2025. Only stockholders of record at the close of business on the record date, or their legal proxy holders, are entitled to notice of and vote at the meeting.

The meeting will be held entirely online via live audio webcast. Please visit www.proxydocs.com/BOLD for more details. You may register to attend the meeting at www.proxydocs.com/BOLD. You will be able to vote online during the meeting as further described beginning on page 2 of the accompanying proxy statement. You will need the control number included on your Notice of Internet Availability of Proxy Materials, your proxy card, or on the instructions that accompanied your proxy materials to attend the meeting. If your shares are held in “street name,” you should contact your bank, broker, or other organization that holds your shares to obtain your control number to attend the meeting. Stockholders and proxy holders attending the meeting online will be deemed to be present in person.

By Order of the Board of Directors,

     /s/ Jessica Oien

    

     Jessica Oien

    

     Chief Legal Officer

    

     San Diego, California

    

     May 6, 2025

    

Please vote your shares promptly to help ensure the presence of a quorum at the meeting. You may vote your shares over the Internet or via a toll-free telephone number. If you received a paper copy of a proxy or voting instruction card by mail, you may submit your proxy or voting instruction card by completing, signing, dating, and returning it. Please follow the instructions in the accompanying proxy statement to vote.

TABLE OF CONTENTS


	Page
GENERAL INFORMATION ABOUT THE MEETING	1
SUMMARY OF MATTERS TO BE VOTED ON	1
QUESTIONS AND ANSWERS ABOUT THE ANNUAL MEETING AND VOTING	2
BOARD OF DIRECTORS	7
CORPORATE GOVERNANCE	10
EXECUTIVE OFFICERS	15
EXECUTIVE COMPENSATION AND OTHER INFORMATION	16
SECURITIES AUTHORIZED FOR ISSUANCE UNDER EQUITY COMPENSATION PLANS	25
SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT	26
CERTAIN RELATIONSHIPS AND RELATED PARTY TRANSACTIONS	29
REPORT OF THE AUDIT COMMITTEE OF THE BOARD	31
PROPOSAL 1 ELECTION OF DIRECTORS	32
PROPOSAL 2 RATIFICATION OF APPOINTMENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM	33
OTHER MATTERS	34
SECTION 16(a) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE	34
ANNUAL REPORT	34

PROXY STATEMENT

2025 ANNUAL MEETING OF STOCKHOLDERS

To be held on June 23, 2025

GENERAL INFORMATION ABOUT THE MEETING

Boundless Bio, Inc. (“Boundless,” “we,” “us,” “our,” or the “Company”) has prepared these materials for use at its 2025 Annual Meeting of Stockholders and any adjournment or postponement thereof (the “Annual Meeting”). The Annual Meeting is scheduled to begin at 8:00 a.m. Pacific Time on Monday, June 23, 2025.

The Annual Meeting will be entirely online via live audio webcast. We believe this technology provides expanded access, improved communication, and cost savings for our stockholders. Hosting a virtual meeting enables increased stockholder attendance and participation from any location around the world.

In accordance with Securities and Exchange Commission (“SEC”) rules, we opted to use the Internet as the primary means of furnishing proxy materials to our stockholders. Accordingly, unless a stockholder previously elected to receive a printed copy of our proxy materials, a Notice of Internet Availability of Proxy Materials (“Notice of Internet Availability”) will be sent to stockholders instead of mailing a printed copy. The Notice of Internet Availability provides instructions on how to access our proxy materials via the Internet and how to request a printed set at no charge. In addition, stockholders can elect to receive future proxy materials electronically or by email or in printed form by mail, and any such election will remain in effect until terminated by the stockholder. We encourage all stockholders to take advantage of the availability of our proxy materials on the Internet to help reduce the cost and environmental impact of our annual meetings.

Our proxy materials will be sent or made available to stockholders on or about May 6, 2025. We are soliciting proxies pursuant to this proxy statement for use at the Annual Meeting.

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting of Stockholders to be held on June 23, 2025: This proxy statement and our 2024 Annual Report are available electronically at www.proxydocs.com/BOLD.

SUMMARY OF MATTERS TO BE VOTED ON


Matter	Board Recommendation	Page Reference for More Information
Proposal 1 – To elect Christine Brennan, Ph.D. and Nancy Whiting, Pharm.D. as Class I directors to hold office until our 2028 annual meeting of stockholders	FOR all nominees	32
Proposal 2 – To ratify the appointment of KPMG LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2025	FOR	33

QUESTIONS AND ANSWERS ABOUT THE ANNUAL MEETING AND VOTING

The information provided in the “question and answer” format below addresses certain frequently asked questions, but is not intended to be a summary of all matters contained in this proxy statement. Please read the entire proxy statement carefully before voting your shares.

Who can attend and vote at the Annual Meeting?

Only our stockholders of record at the close of business on the record date, or their legal proxy holders, are entitled to attend and vote at the Annual Meeting. The record date for the Annual Meeting is April 25, 2025. There were 22,300,043 shares of common stock outstanding and entitled to vote on the record date.

How do I attend the Annual Meeting?

As noted above, the Annual Meeting will be held entirely online via live audio webcast. To attend the Annual Meeting, you will need the control number included on your Notice of Internet Availability, your proxy card, or on the instructions that accompanied your proxy materials. If your shares are held in “street name,” you should contact your bank, broker, or other organization that holds your shares to obtain your control number to attend the Annual Meeting, and if you want to vote online during the meeting, you will need to obtain a legal proxy. See “How do I vote?” below. You must register to attend the Annual Meeting at www.proxydocs.com/BOLD and provide your control number by 2:00 p.m. Pacific Time on June 22, 2025. After completion of your registration, further instructions, including a unique link to access the Annual Meeting, will be emailed to you. Please be aware that you must bear any costs associated with your Internet access, such as usage charges from Internet access providers and telephone or similar companies.

You may submit a question in advance of the Annual Meeting as a part of the registration process. Questions pertinent to the Annual Meeting and that are submitted in accordance with our rules of conduct for the Annual Meeting will be answered during the Annual Meeting, subject to applicable time constraints. Questions and answers may be grouped by topic and substantially similar questions may be grouped and answered once. In order to promote fairness, efficient use of time, and in order to ensure all stockholders are responded to, we will respond to up to two questions from a single stockholder.

What am I voting on?

The list below sets out the matters scheduled for a vote at the Annual Meeting. Each share of our common stock has one vote on each matter.


Proposal 1:		To elect Christine Brennan, Ph.D. and Nancy Whiting, Pharm.D. as Class I directors to hold office until our 2028 annual meeting of stockholders
Proposal 2:		To ratify the appointment of KPMG LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2025

How do I vote?

You are invited to attend the Annual Meeting online to vote on the proposals described in this proxy statement during the meeting, however, you may vote your shares by simply following the instructions below to vote via the Internet, by telephone, or by mail. Even if you intend to attend the Annual Meeting online, we encourage you to vote your shares in advance using one of the methods described below to ensure that your vote will be represented at the Annual Meeting.

Stockholder of Record: Shares Registered in Your Name

If, on the record date, your shares were registered directly in your name with our transfer agent, Computershare Trust Company, N.A., then you are a stockholder of record and you may vote those shares as follows:

•

During the Annual Meeting: You may attend the Annual Meeting online and vote during the meeting online by visiting www.proxydocs.com/BOLD. To vote online during the meeting, you must register to attend the meeting. See “How do I attend the Annual Meeting?” above.

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By Phone: Dial (866) 390-5243, 24 hours a day, seven days a week using any touch-tone telephone and follow the recorded instructions. You will need to use the control number included on your Notice of Internet Availability, your

proxy card, or on the instructions that accompanied your proxy materials to vote by phone. Please vote by 8:59 p.m. Pacific Time on June 22, 2025 to ensure that your vote is counted.

•

By Internet: Complete an electronic proxy card at www.proxypush.com/BOLD, 24 hours a day, seven days a week, by following the instructions provided on the Notice of Internet Availability. You will need to use the control number included in your Notice of Internet Availability, your proxy card, or on the instructions that accompanied your proxy materials to vote via the Internet. Please vote by 8:59 p.m. Pacific Time on June 22, 2025 to ensure that your vote is counted. Please be aware that you must bear any costs associated with your internet access, such as usage charges from internet access providers and telephone companies.

•

By Mail: Complete, sign, and date the proxy card that may be delivered to you and return it in the self-addressed, postage-paid envelope provided. The proxy holders identified in the proxy card will vote all shares of our stock represented by a properly completed and executed proxy received in time for the Annual Meeting in accordance with the stockholder’s instructions. If you submit your executed proxy but do not fill out the voting instructions on the proxy card, the shares represented by your proxy will be voted “FOR” each of the director nominees identified in this proxy statement and “FOR” Proposal 2. If any other matter is properly presented at the Annual Meeting, the proxy holders will vote shares represented by a proxy submitted by a stockholder in accordance with the recommendation of our board of directors.

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

If, on the record date, your shares were held, not 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.” The organization holding those shares is considered to be the stockholder of record for purposes of the Annual Meeting. As a beneficial owner, you have the right to direct the organization holding those shares regarding how to vote such shares. You should have received a notice containing voting instructions from the organization that holds those shares. Follow the instructions provided by that organization to ensure that your vote is counted. If you wish to vote online during the Annual Meeting, you must obtain a legal proxy from the organization that holds those shares. A legal proxy is a written document that authorizes you to vote your shares held in street name at the Annual Meeting. Please contact the organization that holds your shares for instructions regarding obtaining a legal proxy.

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 by completing your proxy card, by telephone, through the Internet, or during the Annual Meeting, your shares will not be voted.

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

If your shares are held in street name, the organization that holds your shares may vote your shares only on certain of the proposals described in this proxy statement without receiving voting instructions from you. If you hold your shares in street name and you do not submit voting instructions to the organization that holds your shares, whether that organization may exercise its discretion to vote your shares depends on whether a particular proposal is considered a “routine” or “non-routine” matter under the rules of the New York Stock Exchange applicable to securities intermediaries (even though we are a Nasdaq-listed company).

We expect the organization that holds your shares will have discretionary voting authority to vote your shares on proposals considered to be “routine” matters even if that organization does not receive voting instructions from you. However, certain organizations may elect not to vote shares without an instruction from the beneficial owner even if they have discretionary authority to do so. We expect Proposal 2 to be considered a “routine” matter.

On the other hand, if you do not provide voting instructions to the organization that holds your shares, we do not expect those shares will be voted on any proposal considered a “non-routine” matter because the organization that holds your shares typically lacks discretionary authority to vote uninstructed shares on non-routine matters. We expect Proposal 1 to be considered a “non-routine” matter.

Organizations may reach conclusions regarding their ability to vote your shares on a particular proposal that differ from our expectations expressed in this proxy statement. Accordingly, we encourage you to provide voting instructions to the organization that holds your shares on all proposals to ensure that your vote is counted. We expect that organizations will vote shares as you have instructed.

What is a “broker non-vote”?

A “broker non-vote” occurs if the organization that holds your shares cannot vote your shares on a particular matter because it has not received instructions from you and it does not have discretionary voting authority on that matter or because the organization that holds your shares chooses not to vote on a matter for which it does have discretionary voting authority.

Can I change my vote after submitting my proxy?

Stockholder of Record: Shares Registered in Your Name

Yes. If you are a stockholder of record, you may revoke your proxy and change your vote:

•

During the Annual Meeting: By attending the Annual Meeting online and voting during the meeting as described above. Your attendance at the Annual Meeting will not automatically revoke your proxy unless you properly vote during the Annual Meeting or specifically request that your prior proxy be revoked by delivering a written notice of revocation that is received by our corporate secretary prior to the Annual Meeting. Any such notice is to be sent to Boundless Bio, Inc., Attention: Corporate Secretary, 10955 Alexandria Way, Suite 100, San Diego, CA 92121.

•

By Phone: By using the phone voting method described above, in which case only your latest telephone proxy received before the deadline for phone voting will be counted.

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By Internet: By using the online voting method described above, in which case only your latest Internet proxy received before the deadline for online voting will be counted.

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By Mail: By signing and returning a new proxy card dated as of a later date, in which case only your latest proxy card received prior to the Annual Meeting will be counted.

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

If you are a beneficial owner of shares held in street name, follow the instructions provided by the organization that holds your shares.

How many votes are required to approve each proposal?

Election of Directors

If a quorum is present at the Annual Meeting, the election of directors will be determined by a plurality of the votes cast by the stockholders entitled to vote on the election. Accordingly, the two nominees receiving the most “FOR” votes from the holders of shares present during the meeting or represented by proxy and entitled to vote on the election of directors will be elected.

You may vote “FOR” or “WITHHOLD” authority to vote for each of the director nominees. If you “WITHHOLD” authority to vote with respect to one or more director nominees, your vote will have no effect on the election of such nominees. Broker non-votes will have no effect on the election of directors.

Other Proposals

If a quorum is present at the Annual Meeting, the outcome of each other proposal presented to the stockholders will be decided by the affirmative vote of the holders of a majority in voting power of the votes cast (excluding abstentions and broker non-votes) on such proposal. Accordingly, abstentions and broker non-votes will have no effect on the outcome of Proposal 2. However, we expect Proposal 2 will be considered a “routine” matter, and therefore broker non-votes are not expected on this proposal. You may vote “FOR,” “AGAINST,” or “ABSTAIN” from voting on each proposal presented at the Annual Meeting other than on the election of directors.

What is the quorum requirement?

A quorum is necessary to hold the Annual Meeting. The holders of a majority in voting power of the shares of our common stock issued and outstanding and entitled to vote, present in person, or by remote communication, or represented by proxy, will constitute a quorum for the transaction of business at the Annual Meeting.

Your shares will be counted for purposes of determining if there is quorum if you are entitled to vote and you are present during the Annual Meeting or you have properly voted by proxy online, by phone or by submitting a proxy card or voting instruction form by mail. Abstentions and broker non-votes will be counted for purposes of determining whether a quorum is present.

A quorum, once established at the Annual Meeting, will not be broken by the withdrawal of enough votes to leave less than a quorum. If, however, a quorum is not present or represented at the Annual Meeting, then either (i) the person presiding over the Annual Meeting, or (ii) a majority in voting power of the stockholders entitled to vote at the Annual Meeting, present in person, or by remote communication, or represented by proxy, will have the power to recess the meeting or adjourn the meeting from time to time until a quorum is present or represented. At any recessed or adjourned meeting at which a quorum is present or represented, any business may be transacted that might have been transacted at the meeting as originally noticed.

What does it mean if I receive more than one Notice of Internet Availability?

If you receive more than one Notice of Internet Availability, your shares may be registered in more than one name or held in different registered accounts. Please follow the voting instructions on each Notice of Internet Availability to ensure that all of your shares are voted.

Am I entitled to dissenters’ rights or appraisal rights?

No. Our stockholders are not entitled to dissenters’ rights or appraisal rights on any of the matters being submitted to stockholders at the Annual Meeting.

How can I find out the results of the voting at the Annual Meeting?

We plan to announce preliminary voting results at the Annual Meeting. Final voting results will be published in a current report on Form 8-K that we expect to file with the SEC within four business days after the Annual Meeting. If final voting results are not available to us in time to file a Form 8-K within four business days after the Annual Meeting, we intend to file a Form 8-K to publish preliminary results and, within four business days after the final results are known to us, file an additional Form 8-K to publish the final results.

Who is paying for this proxy solicitation?

We will pay for the entire cost of soliciting proxies. Our directors and employees may solicit proxies in person, by telephone, or by other means of communication. None of our directors or employees will be paid any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks, and other similar organizations for the cost of forwarding proxy materials to beneficial owners.

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

Stockholders who intend to have a proposal considered for inclusion in our proxy materials for presentation at next year’s annual meeting of stockholders pursuant to Rule 14a-8 under the Securities Exchange Act of 1934, as amended (“Exchange Act”) must submit the proposal to our corporate secretary at our principal executive offices in writing not later than January 6, 2026, which is 120 days prior to the one-year anniversary of the date this proxy statement will be released to stockholders. However, if the date of next year’s annual meeting of stockholders is changed by more than 30 days from the anniversary of this year’s annual meeting of stockholders, then the deadline for such proposals will be a reasonable time before we begin to print and send our proxy materials. These proposals must comply with the requirements as to form and substance established by the SEC in Rule 14a-8 of the Exchange Act for such proposals in order to be included in the proxy statement.

Stockholders intending to present a proposal at next year’s annual meeting of stockholders, but not to include the proposal in our proxy statement, or to nominate a person for election as a director, must comply with the requirements set forth in our amended and restated bylaws. Our amended and restated bylaws require, among other things, that our corporate secretary receive written notice from the stockholder of record of their intent to present such proposal or nomination not earlier than the close of business on the 120th day and not later than the close of business on the 90th day prior to the anniversary of the preceding year’s annual meeting. Therefore, we must receive notice of such a proposal or nomination for next year’s annual meeting of stockholders no earlier than the close of business on February 26, 2026 and no later than the close of business on March 28, 2026. The notice must contain the information required by our amended and restated bylaws, a copy of which is available upon written request to our corporate secretary. In the event that the date of next year’s annual meeting of stockholders is more than 30 days before or more than 60 days after the one-year anniversary of this year’s annual meeting of stockholders, then our

corporate secretary must receive such written notice not earlier than the close of business on the 120th day and not later than the close of business on the 90th day prior to next year’s annual meeting of stockholders or, if later, the close of business on the 10th day following the day on which public disclosure of the date of such annual meeting is first made by the Company. SEC rules permit management to vote proxies in its discretion in certain cases if the stockholder does not comply with this deadline and, in certain other cases, notwithstanding the stockholder’s compliance with this deadline. Stockholders are advised to review our amended and restated bylaws which also specify requirements as to the form and content of a stockholder’s notice.

In addition to satisfying the foregoing requirements under our amended and restated bylaws, including with respect to the deadline for notices disclosed above, to comply with the universal proxy rules, stockholders who intend to solicit proxies in support of director nominees other than our nominees must provide notice that sets forth the information required by Rule 14a-19 under the Exchange Act.

We intend to file a proxy statement and WHITE proxy card with the SEC in connection with the solicitation of proxies for next year’s annual meeting of stockholders. We reserve the right to reject, rule out of order, or take other appropriate action with respect to any proposal that does not comply with these or other applicable requirements.

Our principal executive offices are currently located at 10955 Alexandria Way, Suite 100, San Diego, CA 92121.

If a stockholder does not also comply with the requirements of Rule 14a-4(c)(2) under the Exchange Act, we may exercise discretionary voting authority under proxies that we solicit to vote in accordance with our best judgment on any such stockholder proposal or nomination.

Householding

We have adopted an SEC-approved procedure called “householding.” This procedure potentially means extra convenience for stockholders and cost savings for companies. Under this procedure, we send only one copy of the Notice of Internet Availability, and if applicable, Notice of Annual Meeting of Stockholders, Proxy Statement, and Annual Report, to stockholders of record who share the same address and last name, unless one of those stockholders notifies us that the stockholder would like a separate copy of such documents. If, at any time, you no longer wish to participate in householding and would prefer to receive a separate copy of the Notice of Internet Availability, and if applicable, Notice of Annual Meeting of Stockholders, Proxy Statement, and Annual Report, from the other stockholder(s) sharing your address, please direct your written request to our transfer agent, Computershare Trust Company, N.A., at P.O. Box 43078, Providence, RI 02940-3078, or contact our transfer agent by phone at 800-736-3001. We undertake to deliver promptly, upon any such oral or written request, a separate copy of the Notice of Internet Availability, and if applicable, Notice of Annual Meeting of Stockholders, Proxy Statement, and Annual Report, to a stockholder at a shared address to which a single copy of these documents was delivered. Similarly, if stockholders of record sharing the same address are receiving multiple copies of the Notice of Internet Availability, or if applicable, Notice of Annual Meeting of Stockholders, Proxy Statement, and Annual Report, and such stockholders would like a single copy to be delivered to them in the future, such stockholders may make such a request by contacting us by the means described above.

If you wish to update your participation in householding and you are a beneficial owner who holds shares in “street name” with a broker, bank, or similar organization, you may contact your broker, bank, or other organization.

BOARD OF DIRECTORS

The business and affairs of the Company is managed under the direction of our board of directors (“Board”), which is currently comprised of seven members. In accordance with our amended and restated certificate of incorporation, our Board is divided into three classes, with one class of directors standing for election each year, for a three-year term. The current terms of our Class I directors will expire at the Annual Meeting. Our Class I directors have been nominated for re-election at the Annual Meeting with the new term to expire at our annual meeting of stockholders to be held in 2028. The current terms of our Class II and Class III directors will expire at our annual meetings of stockholders to be held in 2026 and 2027, respectively.

The following table sets forth the name, age, and certain other information of each member of our Board as of April 25, 2025.


Name	Director Class	Age	Position	Independent
Jonathan E. Lim, M.D.	III	53	Chairman of the Board	X
Christine Brennan, Ph.D.	I	56	Director	X
Kristina Burow	II	51	Director	X
James Christensen, Ph.D.	II	57	Director	X
Zachary D. Hornby	III	46	President, Chief Executive Officer, and Director
Jennifer Lew	III	52	Director	X
Nancy Whiting, Pharm.D.	I	52	Director	X

Nominees for Election at the Annual Meeting

Class I Directors

Christine Brennan, Ph.D. has served as a member of our Board since February 2022. Dr. Brennan has been a Managing Director at Vertex Ventures HC since 2022 and previously was Partner at MRL Ventures Fund from 2017 to 2021 and Principal at the Novartis Venture Fund from 2013 to 2017. During her career as a venture capital investor, Dr. Brennan has served on the board of directors of biotechnology and biopharmaceutical companies, including Alector, Inc., Entrada Therapeutics, Inc., and Altimmune, Inc. (while the companies were privately held). Prior to the Novartis Venture Fund, Dr. Brennan was Chief Business Officer at Vitae Pharmaceuticals (acquired by Allergan) from 2010 to 2013. Dr. Brennan received a B.S. in Biochemistry from the University of New Hampshire, a Ph.D. in Neuroscience from Dartmouth Medical School, and conducted a postdoctoral fellowship in Developmental Neurobiology at the National Institutes of Health. Dr. Brennan’s extensive investment experience in the biopharmaceutical industry, as well as her experience on numerous biotechnology and biopharmaceutical company boards of directors, contributed to our Board’s conclusion that she should serve as a director of our Company.

Nancy Whiting, Pharm.D. has served as a member of our Board since October 2023. Since September 2021, Dr. Whiting has been the Chief Executive Officer and a member of the board of directors of Recludix Pharma, a privately held company developing novel treatments for inflammatory disease and cancer. Prior to Recludix, Dr. Whiting held various positions at Seagen Inc. (formerly Seattle Genetics, Inc.) for approximately 15 years from March 2007 to September 2021, where she served most recently as Executive Vice President of Corporate Strategy, Alliances, and Communication. Prior to this role at Seagen, Dr. Whiting served as Executive Vice President of Late Stage Development, Senior Vice President of Clinical Development and Medical Affairs, and Head of Experimental Medicine. During her tenure at Seagen, Dr. Whiting played a central role in the development and regulatory approvals of cancer medicines Adcetris® (brentuximab vedotin), Padcev® (enfortumab vedotin-ejfv), Tukysa® (tucatinib), and Tivdak® (tisotumab vedotin). Prior to her career in the pharmaceutical industry, Dr. Whiting practiced as a clinical oncology pharmacist at the Seattle Cancer Care Alliance. Dr. Whiting has served as a member of the board of directors of Caribou Biosciences, a publicly traded biopharmaceutical company since August 2021. She received her Pharm.D. from the University of Washington and her B.Sc. in Pharmaceutical Sciences from the University of British Columbia. Dr. Whiting’s extensive experience in all phases of drug development contributed to our Board’s conclusion that she should serve as a director of our Company.

Continuing Directors

Class II Directors

Kristina Burow has served as a member of our Board since June 2019. Ms. Burow has served as a Managing Director of ARCH Venture Partners, a venture capital firm, since November 2011 and previously held positions of increasing responsibility at ARCH from August 2002 to November 2011. Ms. Burow is a co-founder and member of the board of directors of Neumora Therapeutics, Inc., a publicly traded biopharmaceutical company, and Orbital Therapeutics Inc., a privately held biotechnology company. Ms. Burow currently serves on the board of directors of Metsera, Inc., a publicly traded biotechnology company, and Scholar Rock Holding Corporation, a publicly traded biopharmaceutical company. She is also a member of the

board of directors of several privately held biopharmaceutical and biotechnology companies, including: Architect Therapeutics, Inc.; Autobahn Therapeutics, Inc.; Magnet Biomedicine, Inc.; Mirador Therapeutics, Inc.; Pretzel Therapeutics, Inc.; ROME Therapeutics, Inc.; and Treeline Biosciences, Inc. Ms. Burow previously was a co-founder and member of the board of directors of Receptos Inc., a publicly traded pharmaceutical company, until its acquisition by Celgene Corporation in 2015. Ms. Burow also previously served as a member of the board of directors of a number of other publicly traded and privately held biopharmaceutical and biotechnology companies, including the following publicly traded companies: Beam Therapeutics Inc.; Gossamer Bio, Inc.; Metacrine, Inc.; Unity Biotechnology, Inc.; and Vir Biotechnology Inc. Ms. Burow has participated and led investments in many other ARCH portfolio companies including: Erasca, Inc.; Aledade, Inc.; Kythera Biopharmaceuticals, Inc. (acquired by Allergan plc); Kura Oncology, Inc.; and Ikaria, Inc. (acquired by Madison Dearborn Partners, a private equity firm). Prior to joining ARCH, Ms. Burow served as an associate with the Novartis BioVenture Fund and was an early employee at the Genomics Institute of the Novartis Research Foundation. Ms. Burow received a B.S. in Chemistry from the University of California, Berkeley, an M.A. in Chemistry from Columbia University, and an M.B.A. from the University of Chicago. Ms. Burow’s extensive experience serving on the board of directors of clinical-stage biotechnology companies and her investment experience in the life sciences industry contributed to our Board’s conclusion that she should serve as a director of our Company.

James “Jamie” Christensen, Ph.D. has served as a member of our Board since October 2023. Dr. Christensen has been the President and Head of Research and Development of Terremoto Biosciences, Inc., a privately held biotechnology company, since January 2025. Prior to Terremoto, he served as the Chief Scientific Officer of Mirati Therapeutics, a publicly traded precision oncology company, from January 2014 to October 2024, Senior Vice President from January 2014 to December 2018, and Vice President, Research from June 2013 to January 2014. In his roles at Mirati, Dr. Christensen was responsible for overseeing drug discovery, early clinical development, manufacturing, and companion diagnostics research, and led activities related to the discovery and advancement of key clinical and preclinical programs, including Mirati’s first approved product, Krazati® (adagrasib). Prior to Mirati, Dr. Christensen was the Head of Oncology Precision Medicine and a member of the executive leadership team in the Oncology Research Unit at Pfizer. He joined Pfizer in 2003, where his responsibilities included leading oncology nonclinical research and translational sciences for programs including Sutent® (sunitinib malate) and Xalkori® (crizotinib). Prior to Pfizer, Dr. Christensen held positions at Sugen Inc. (acquired by Pharmacia), as a group leader in preclinical research and exploratory development. He began his career in the pharmaceutical industry at Warner Lambert/Parke-Davis. Dr. Christensen has authored or co-authored numerous peer-reviewed research articles in scientific journals including Science, Nature, Cancer Cell, Cancer Discovery, New England Journal of Medicine, and many others. He received his Ph.D. and M.S. in Pharmacology and Toxicology at North Carolina State University and his B.S. in Biology from Northern Illinois University. Dr. Christensen’s extensive executive and research experience in the biopharmaceutical industry contributed to our Board’s conclusion that he should serve as a director of our Company.

Class III Directors

Zachary D. Hornby has served as our President, Chief Executive Officer, and as a member of our Board since May 2019. Previously, Mr. Hornby served in several executive positions at Ignyta, Inc., a publicly traded precision oncology company acquired by Roche in February 2018, including as its Chief Operating Officer from June 2014 to July 2018 and prior to that as its Chief Financial Officer from July 2013 to May 2014 and Vice President of Corporate Development from August 2012 to July 2013. In these roles, Mr. Hornby led the operational team responsible for the development of Rozlytrek® (entrectinib) and the efforts ultimately leading to the acquisition by Roche. Prior to Ignyta, Mr. Hornby served as Senior Director of Business Development at Fate Therapeutics, a cellular immunotherapy company focused on oncology and immunology, and various business and corporate development roles at Halozyme Therapeutics, Inc. In addition, Mr. Hornby held earlier roles in new product planning, marketing, and strategy at Neurocrine Biosciences and L.E.K. Consulting. Mr. Hornby serves as a member of the board of directors of Radionetics Oncology, Inc., a privately held biotechnology company. Mr. Hornby received a B.S and a M.S. in Biology from Stanford University, and an M.B.A. from Harvard Business School. Mr. Hornby’s knowledge of our business, his background in corporate strategy and finance, and his extensive executive experience at multiple biopharmaceutical companies contributed to our Board’s conclusion that he should serve as a director of our Company.

Jennifer Lew has served as a member of our Board since January 2022. Ms. Lew has been the Executive Vice President and Chief Financial Officer of Annexon, Inc., a publicly traded biopharmaceutical company, since June 2019. Prior to Annexon, she served as Chief Financial Officer and previously Senior Vice President, Finance for Aduro Biotech, Inc., which merged with Chinook Therapeutics, Inc. (acquired by Novartis), from 2013 to May 2019. Prior to Aduro, Ms. Lew held various finance roles at Dynavax Technologies Corporation, a publicly traded biopharmaceutical company, from 2004 to 2013, and QRS Corporation, a publicly held technology company, from 2000 to 2004. Ms. Lew began her career in the audit practice at Ernst & Young from 1994 to 1999. Ms. Lew received a B.A. in Economics/Accounting and Government from Claremont McKenna College and is a Certified Public Accountant (inactive status). Ms. Lew’s background in leadership, finance, and accounting at privately held and publicly traded biotechnology and biopharmaceutical companies contributed to our Board’s conclusion that she should serve as a director of our Company.

Jonathan E. Lim, M.D. co-founded Boundless and has served as our Chairman since December 2018. Dr. Lim also co-founded Erasca, Inc., a publicly traded precision oncology company, in July 2018, joined as Executive Chairman in October 2018, and has served as Chairman and Chief Executive Officer since March 2019. Dr. Lim has also served as a Venture Partner at ARCH Venture Partners since December 2018 and as Managing Partner at City Hill, LLC since founding it in 2010. Prior to co-founding each of Boundless and Erasca, Dr. Lim co-founded and served as Chairman of Ignyta, Inc., a publicly traded precision oncology company, and led it from 2012 as Chairman, Chief Executive Officer, and President through its acquisition by Roche in February 2018 and subsequent integration into Roche and Genentech in July 2018. During his tenure at Ignyta, Dr. Lim co-founded Bonti, Inc., a privately held biotechnology company, and served as its Chairman from February 2016 until its acquisition by Allergan plc in October 2018. Prior to joining Ignyta, Dr. Lim served as Chairman and Chief Executive Officer of Eclipse Therapeutics, Inc., a privately held oncology company targeting cancer stem cells that he co-founded in March 2011 as a spinout from Biogen Idec and that was sold to Bionomics Ltd. in 2012. Prior to Eclipse, Dr. Lim served as the President, Chief Executive Officer, and a Director (including as Chairman from 2004 to 2005) of Halozyme Therapeutics, Inc., a publicly traded biotechnology company, from May 2003 to December 2010. Prior to Halozyme, Dr. Lim’s experience included management consulting at McKinsey & Company, a National Institutes of Health Postdoctoral Fellowship at Harvard Medical School and the Dana-Farber Cancer Institute, and two years of general surgery residency at New York Hospital- Cornell and Memorial Sloan Kettering Cancer Center. Dr. Lim has also served as a member of the board of directors of Maze Therapeutics, Inc., a publicly traded biopharmaceutical company advancing precision medicines for both rare and common diseases, since October 2019. Dr. Lim has been a member of the Board of Overseers at Scripps Research since October 2018, a member of the Board of Visitors of the Moores Cancer Center at the University of California, San Diego since 2015, and a member of the Stanford Interdisciplinary Biosciences Council since 2014. Dr. Lim has B.S. and M.S. degrees from Stanford University, an M.D. from McGill University, and an M.P.H. from Harvard University. Dr. Lim’s intimate knowledge of our business as a co-founder and his extensive experience as an executive officer and director of multiple public and private biotechnology companies contributed to our Board’s conclusion that he should serve as a director of our Company.

CORPORATE GOVERNANCE

Code of Conduct and Ethics

We have adopted a written Code of Business Conduct and Ethics that applies to all of our directors, officers, and employees, including our principal executive officer and our principal financial and accounting officer, which is accessible in the “Investors” section of our website at https://investors.boundlessbio.com under “Governance Overview.” Our directors, officers, and employees are expected to be familiar with our Code of Business Conduct and Ethics and to adhere to the principles and procedures set forth therein. We intend to disclose any changes to our Code of Business Conduct and Ethics or waivers from it that apply to our principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions by posting such information on our website or by filing with the SEC a current report on Form 8-K, in each case in accordance with applicable SEC rules and Nasdaq listing rules. Information contained on or available through our website is not incorporated by reference in, or considered part of, this proxy statement. We will provide any person, without charge, a copy of our Code of Business Conduct and Ethics upon written request to Boundless Bio, Inc., 10955 Alexandria Way, Suite 100, San Diego, CA 92121, Attention: Investor Relations.

Corporate Governance Guidelines

We believe in sound corporate governance practices and our Board adopted formal Corporate Governance Guidelines to assist our Board in the exercise of its responsibilities and to serve our interests and those of our stockholders. The Corporate Governance Guidelines provide a framework within which our Board conducts its business, and they address matters including board size and composition, director qualification standards and additional selection criteria, conflicts of interest, board meetings, board committees, succession planning, oversight of risk management, and investigation of reports received through our ethics hotline. Our Corporate Governance Guidelines are accessible in the same section of our website as our Code of Business Conduct and Ethics.

Director Independence

As required under Nasdaq listing rules, 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. Our Board consults with our legal counsel to ensure that our Board’s determinations are consistent with relevant securities and other laws and regulations regarding the definition of “independent,” including those set forth in Nasdaq listing rules, as in effect from time to time. Consistent with these considerations, our Board affirmatively determined that all of our directors, other than Mr. Hornby, our president and chief executive officer, are “independent directors” in accordance with the pertinent Nasdaq listing rules. Mr. Hornby is not considered independent because he is one of our executive officers.

The Nasdaq independence definition includes a series of objective tests, including that the director is not, and has not been for at least three years, one of our employees and that neither the director nor any of his or her family members has engaged in various types of business dealings with us. In addition, as required by Nasdaq listing rules, our Board made a subjective determination as to each independent director that no relationships exist, which, in the opinion of our Board, would interfere with the exercise of independent judgment in carrying out the responsibilities of the director. In making these determinations, our Board reviewed and discussed information provided by the directors and us with regard to each director’s business and personal activities and relationships as they may relate to us and our management. There are no family relationships among any of our directors or executive officers.

As required under Nasdaq listing rules, our independent directors meet in regularly scheduled executive sessions without our non-independent director or other management present.

Director Nominations

Our Nominating and Corporate Governance Committee is responsible for identifying individuals qualified to become members of our Board, consistent with criteria approved by our Board, and recommending director nominees to our Board. To that end, our Nominating and Corporate Governance Committee is responsible for ensuring that our Board has the requisite expertise and that its membership consists of persons with sufficiently diverse and independent backgrounds. Our Nominating and Corporate Governance Committee monitors the mix of specific experience, qualifications, skills, and backgrounds of our directors to help assure that our Board, as a whole, has the necessary tools to perform its oversight function effectively in light of our business and structure. In evaluating the suitability of individual candidates (both new candidates and current members) for election or appointment, our Nominating and Corporate Governance Committee, in recommending director candidates, and our Board, in nominating (and, in the case of any vacancy, appointing) such candidates, evaluates candidates in accordance with the qualification standards set forth in our Corporate Governance Guidelines. Namely, they consider candidates who have a high

level of personal and professional integrity, strong ethics and values, and ability to make mature business judgments, as well as whether there are potential conflicts of interest with the candidate’s other personal and professional pursuits. Our Nominating and Corporate Governance Committee and our Board may also consider the following factors, as well as any other factor that they deem relevant:

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experience in corporate management, such as serving as an officer or former officer of a publicly-held company;

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experience as a board member or executive officer of another publicly-held company;

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professional and academic experience relevant to our industry;

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strength of leadership skills;

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diversity of expertise and experience in substantive matters pertaining to our business relative to other board members;

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diversity of background and perspective, including, but not limited to, with respect to age, gender, race, place of residence, and specialized experience;

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experience in finance and accounting and/or executive compensation practices; and

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time required for preparation, participation, and attendance at Board meetings and committee meetings, if applicable.

Currently, our Board evaluates each individual in the context of our Board as a whole, with the objective of assembling a group that can best maximize the success of the business and represent stockholder interests through the exercise of sound judgment using its diversity of experience in these various areas.

If our Nominating and Corporate Governance Committee determines that an additional or replacement director is required or advisable, then the committee will identify the desired skills and experience of a new nominee in light of the criteria above and generally with input from other directors and management, and may take such measures as it considers appropriate in connection with its identification and evaluation of a director candidate, including engagement of an outside search firm, consideration of candidates recommended by members of our Board, management, and other sources, inquiry of the person or persons making the recommendation, candidate interviews, and background checks.

We do not have a formal policy with regard to the consideration of director candidate recommendations from our stockholders. However, any such recommendations received from stockholders will be evaluated in the same manner that individuals recommended by our directors, management, or other parties are evaluated. Accordingly, our Board does not believe a formal policy regarding consideration of stockholder director nomination recommendations is necessary. Any such recommendations should be made in writing directed to our Nominating and Corporate Governance Committee, care of our corporate secretary at our principal executive offices, and should include the information required by the advance notice procedures with respect to director nominations by stockholders described in our amended and restated bylaws, including information regarding the recommended candidate and recommending stockholder. To give our Nominating and Corporate Governance Committee sufficient time to evaluate a recommended candidate and include the candidate in our proxy statement for the annual meeting, the recommendation should be received by our corporate secretary at our principal executive offices in accordance with such advance notice procedures described in our amended and restated bylaws. If a stockholder wishes to propose a candidate for consideration as a nominee for election to our Board, the stockholder must follow the procedures described in our amended and restated bylaws, including the advance notice procedures therein. For information regarding the advance notice procedures, please see “Questions and Answers About the Annual Meeting and Voting— When are stockholder proposals and director nominations due for next year’s annual meeting?” above.

Board Leadership Structure

Our Board is currently chaired by Dr. Lim. Our Board recognizes that it is important to determine an optimal board leadership structure to ensure the independent oversight of management as the Company continues to grow. We separate the roles of chief executive officer and chairman of the board of directors in recognition of the differences between the two roles. Our chief executive officer is responsible for setting the strategic direction of our company and the day-to-day leadership and performance of our company, while the chairman of the board provides guidance to our chief executive officer and presides over meetings of the full Board. We believe that this separation of responsibilities provides a balanced approach to managing our Board and overseeing our Company. Our Nominating and Corporate Governance Committee recommended and our Board concluded that our current leadership structure continues to be appropriate for us at this time. However, our Nominating and Corporate Governance Committee and our Board will continue to periodically review our leadership structure and our Board may make such changes in the future as it deems appropriate.

Role of Board in Risk Oversight Process

Our Board has responsibility for the oversight of our risk management processes and, either as a whole or through its committees, regularly discusses with management our major risk exposures, their potential impact on our business, and the steps we take to manage them. The risk oversight process includes receiving regular reports from Board committees and members of senior management to enable our Board to understand our risk identification, risk management, and risk mitigation strategies with respect to areas of potential material risk, including operations, finance, legal, regulatory, strategic, and reputational risk.

Our Audit Committee reviews information regarding liquidity and operations and oversees our management of financial risks. Our Audit Committee also oversees the management of our information technology risks, including cybersecurity and data privacy risks. Periodically, our Audit Committee reviews our policies with respect to risk assessment, risk management, loss prevention, and regulatory compliance. Oversight by our Audit Committee includes direct communication with our external auditors and discussions with management regarding significant risk exposures and the actions management has taken to limit, monitor, or control such exposures. Our Compensation Committee is responsible for assessing whether any of our compensation policies or programs has the potential to encourage excessive risk-taking. Our Nominating and Corporate Governance Committee manages risks associated with the independence of our Board, corporate disclosure practices, and potential conflicts of interest. While each committee is responsible for evaluating certain risks and overseeing the management of such risks, our entire Board is regularly informed through committee reports about such risks. Matters of significant strategic risk are considered by our Board as a whole.

Committees of the Board and Committee Member Independence

Our Board has established three standing committees – Audit, Compensation, and Nominating and Corporate Governance – comprised of the directors identified in the table below. Each committee operates under a written charter adopted by our Board that sets out its role and responsibilities and satisfies applicable SEC rules and regulations and Nasdaq listing rules. A copy of each committee charter is available in the “Investors” section of our website at https://investors.boundlessbio.com under “Governance Overview.” Information contained on or available through our website is not incorporated by reference in, or considered part of, this proxy statement.


			Nominating and
Name of Director	Audit	Compensation	Corporate Governance
Jonathan E. Lim, M.D.	X	C
Christine Brennan, Ph.D.	X		C
Kristina Burow		X	X
James Christensen, Ph.D.		X
Zachary D. Hornby
Jennifer Lew	C†	X
Nancy Whiting, Pharm.D.			X

C Committee Chair

† Audit Committee Financial Expert

Our Board has determined that all committee members are independent under applicable Nasdaq listing rules and SEC rules and regulations of committee membership. With respect to the members of our Audit Committee, our Board also determined that all members meet the requirements for financial literacy under the applicable SEC rules and regulations and Nasdaq listing rules, and that Ms. Lew is an “audit committee financial expert” as defined in Item 407(d)(5) of Regulation S-K. With respect to the members of our Compensation Committee, our Board also determined that each of Ms. Burow, Dr. Christensen, Ms. Lew, and Dr. Lim is a “non-employee director” as defined in Rule 16b-3 promulgated under the Exchange Act. Each of our Board’s committees report regularly to our Board regarding its activities in fulfilling its responsibilities as detailed in the committee’s charter.

Audit Committee

Our Audit Committee was established in accordance with Section 3(a)(58)(A) of the Exchange Act. Our Audit Committee’s main function is to oversee our accounting and financial reporting processes and the audits of our financial statements. This committee’s responsibilities include, among other things:

•

appointing our independent registered public accounting firm;

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

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approving the audit and non-audit services to be performed by our independent registered public accounting firm;

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

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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;

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reviewing on a periodic basis, or as appropriate, any investment policy and recommending to our Board any changes to such investment policy;

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reviewing our earnings announcements and other public announcements regarding our results of operations;

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preparing the report of our Audit Committee that the SEC requires in our annual proxy statement;

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reviewing our policies with respect to risk assessment and management and oversee management of our information technology risks, including cybersecurity and data privacy risks;

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adopting and overseeing procedures to address complaints regarding accounting, internal accounting controls and auditing matters, including confidential, anonymous submissions by our employees of concerns regarding questionable accounting or auditing matters;

•

reviewing and approving any related party transactions and periodically reviewing our written related person transaction policy;

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reviewing and monitoring compliance with our Code of Business Conduct and Ethics; and

•

periodically reviewing and evaluating the performance of our Audit Committee.

Compensation Committee

Our Compensation Committee approves policies relating to compensation and benefits of our officers and employees. Our Compensation Committee approves corporate goals and objectives relevant to the compensation of our chief executive officer and other executive officers, evaluates the performance of these officers in light of those goals and objectives, and has the authority to approve or make recommendations to our Board regarding the compensation of these officers based on such evaluations. Our Compensation Committee has the authority to review and approve or make recommendations to our Board regarding the Company’s incentive compensation and equity-based plans and arrangements, administer such plans, and make grants of stock options and other awards under our such plans. Our Compensation Committee also administers and oversees compliance with our Policy for Recovery of Erroneously Awarded Compensation. In fulfilling its responsibilities, our Compensation Committee has the authority to delegate any or all of its responsibilities to a subcommittee of the committee and the authority to authorize an officer of the Company to grant rights or options to officers (other than executive officers) and employees, in a manner that is in accordance with applicable law. Our Compensation Committee is responsible for periodically reviewing and evaluating its performance.

Our Compensation Committee is authorized to retain the services of one or more executive compensation advisors, as it sees fit, in connection with the establishment of our compensation programs and related policies. In 2024, our Compensation Committee retained Alpine Rewards, LLC (“Alpine Rewards”), which is an independent compensation consultant, to provide it with information, recommendations, and other advice relating to executive compensation and director compensation. Our Compensation Committee assessed the independence of Alpine Rewards pursuant to SEC rules and regulations and Nasdaq listing rules and concluded that no conflict of interest existed that would have prevented Alpine Rewards from serving as an independent consultant to our Compensation Committee currently or during 2024.

Nominating and Corporate Governance Committee

Our Nominating and Corporate Governance Committee is responsible for assisting our Board in discharging our Board’s responsibilities regarding the identification of qualified candidates to become Board members, the selection of nominees for election as directors at our annual meetings of stockholders (or special meetings of stockholders at which directors are to be elected), and the selection of candidates to fill any vacancies on our Board and any committees thereof. In addition, our Nominating and Corporate Governance Committee is responsible for overseeing our corporate governance policies, reporting, and making recommendations to our Board concerning governance matters, reviewing, and assisting our Board with oversight of matters relating to environmental, social, and governance matters affecting the Company, and oversight of the self-evaluations

of our Board and its committees. Our Nominating and Corporate Governance Committee is responsible for periodically reviewing and evaluating its performance.

Meetings of the Board and its Committees

During 2024, our Board met five times, our Audit Committee met four times, our Compensation Committee met three times, and our Nominating and Corporate Governance Committee did not meet. Each director attended at least 75% of the aggregate number of meetings of our Board and meetings of the committees on which such director served during 2024 during the periods that such director served.

Communication with the Board

Our Board will give appropriate attention to written communications that are submitted by stockholders, and will respond if and as appropriate. Our corporate secretary is primarily responsible for reviewing such communications from stockholders and for providing copies or summaries to the directors as she considers appropriate. Communications are forwarded to all directors if they relate to important substantive matters and include suggestions or comments that our corporate secretary and chairman of our Board consider to be important for the directors to know. In general, communications relating to corporate governance and long-term corporate strategy are more likely to be forwarded than communications relating to ordinary business affairs, personal grievances, and matters as to which we tend to receive repetitive or duplicative communications. Stockholders who wish to send communications on any topic to our Board should address such communications to our Board in writing: Boundless Bio, Inc., Attention: Corporate Secretary, 10955 Alexandria Way, Suite 100, San Diego, CA 92121.

Attendance of Directors at the Annual Meeting of Stockholders

Our Board has adopted a policy under which all directors are encouraged to attend our annual meeting of stockholders.

Insider Trading Compliance Policy and Procedures

We have adopted an Insider Trading Compliance Policy and Procedures governing the purchase, sale, and/or other dispositions of our securities by our directors, officers, and employees that we believe are reasonably designed to promote compliance with insider trading laws, rules and regulations, and any applicable Nasdaq listing rules. A copy of our Insider Trading Compliance Policy and Procedures was filed as Exhibit 19.1 to our Annual Report on Form 10-K for the year ended December 31, 2024 filed with the SEC on March 27, 2025. In addition, it is our policy to comply with applicable laws, rules and regulations, and any applicable Nasdaq listing rules when engaging in transactions in our own securities.

Prohibition Against Hedging

Our Insider Trading Compliance Policy and Procedures prohibits our directors, officers, and employees from engaging in hedging transactions involving our securities, such as prepaid variable forward contracts, equity swaps, collars, and exchange funds, or other transactions that hedge or offset, or are designed to hedge or offset, any decrease in the market value of our equity securities.

EXECUTIVE OFFICERS

The following table sets forth the name, age, and position(s) of each of our executive officers as of April 25, 2025.


Name	Age	Position
Zachary D. Hornby	46	President, Chief Executive Officer, and Director
Robert Doebele, M.D., Ph.D.	54	Chief Medical Officer
Christian Hassig, Ph.D.	53	Chief Scientific Officer
David Hinkle	63	Senior Vice President, Finance, Controller, and Corporate Treasurer
Jessica Oien, J.D.	54	Chief Legal Officer and Corporate Secretary

The following is biographical information for our executive officers other than Mr. Hornby, whose biographical information is included under the section titled “Board of Directors” above.

Robert Doebele, M.D., Ph.D. has served as our Chief Medical Officer since February 2025. Prior to joining Boundless, in April 2017, Dr. Doebele co-founded Rain Oncology Inc., a publicly traded, clinical-stage precision oncology company acquired by Pathos AI, Inc. in January 2024. At Rain and until its acquisition, Dr. Doebele served as President since April 2021, Chief Scientific Officer since May 2021, and Chief Medical Officer since June 2023. Prior to Rain, from July 2008 to September 2020, he was an Assistant, and then Associate Professor of Medicine in the Division of Medical Oncology at the University of Colorado School of Medicine. He also served as the Director of the Thoracic Oncology Research Initiative and co-Director of the Molecular Tumor Board at the University of Colorado Cancer Center. Dr. Doebele led the research at the University of Colorado that launched the tropomyosin receptor kinase (TRK) fusion cancer field by demonstrating that NTRK1/2/3 gene fusions represent a novel tumor agnostic target in cancer, a strategy that ultimately led to the approvals of Vitrakvi® (larotrectinib) and Rozlytrek® (entrectinib). Dr. Doebele received his A.B. in Molecular Biology from Princeton University and received his M.D. and Ph.D. in Immunology from the University of Pennsylvania. He conducted his internal medicine residency and a medical oncology fellowship at the University of Chicago.

Christian “Chris” Hassig, Ph.D. has served as our Chief Scientific Officer since November 2019. Before Boundless, Dr. Hassig was with Sierra Oncology, Inc., a publicly traded precision oncology company, where he served in various leadership roles including Chief Scientific Officer and Senior Vice President of Research, from June 2016 to November 2019. Prior to Sierra, Dr. Hassig served as Vice President of Drug Discovery at the Sanford Burnham Prebys Medical Discovery Institute where he led the discovery and development of novel small molecule therapeutics against innovative targets. Dr. Hassig also held several positions within the Biology and Lead Discovery departments at Kalypsys, Inc., a private biopharmaceutical company specializing in small molecule drug discovery and development. Dr. Hassig received a B.A. in Chemistry and Biochemistry from the University of California, San Diego, a Ph.D. in Molecular and Cellular Biology from Harvard University, and completed a Postdoctoral Fellowship at the University of California, Berkeley.

David Hinkle has served as our Senior Vice President, Finance and Controller since June 2023 and as our Treasurer since October 2024. He joined us in June 2021 as our Vice President, Finance and Controller. Prior to Boundless, Mr. Hinkle served as Vice President, Finance and Controller at Crinetics Pharmaceuticals, Inc., a publicly traded clinical-stage pharmaceutical company, from July 2018 to May 2021, where he was responsible for developing and leading their accounting team after their initial public offering in July 2018. Prior to Crinetics, Mr. Hinkle served in similar capacities at Ignyta, Inc., a publicly traded precision oncology company acquired by Roche in February 2018, Receptos Inc., a publicly traded biopharmaceutical company acquired by Celgene Corporation in 2015, Somaxon Pharmaceuticals, Inc., a publicly traded specialty pharmaceutical company acquired by Pernix Therapeutics Holdings, Inc. in 2013, and Digirad, where he was responsible for accounting operations. Mr. Hinkle began his career at Deloitte. He earned a B.S. from California State University, Northridge and is a Certified Public Accountant (inactive status) in California.

Jessica Oien has served as our Chief Legal Officer and Corporate Secretary since January 2024 and previously served as our General Counsel and Corporate Secretary from August 2021 through December 2023. Prior to joining Boundless, Ms. Oien served as General Counsel and Corporate Secretary at Cidara Therapeutics, Inc., a publicly traded biotechnology company, from September 2018 to August 2021. Before Cidara, Ms. Oien served as Vice President, Legal and Compliance at Otonomy, Inc., a publicly traded biopharmaceutical company, where she was the legal lead for the commercial business from 2015 to 2018 and spearheaded the commercial compliance program. She served in similar roles as Vice President, Legal and Compliance for Pernix Therapeutics, Vice President, Legal Affairs and Compliance for Somaxon Pharmaceuticals, Senior Director, Legal Affairs for Verus Pharmaceuticals, and Senior Director, Legal Affairs at Elan Pharmaceuticals. Ms. Oien began her legal career as corporate counsel at national law firms including Brobeck, Phleger & Harrison LLP and Milbank, Tweed, Hadley & McCloy LLP. Ms. Oien received a B.A. in Economics and Political Science from North Dakota State University and a J.D. from Loyola Law School.

EXECUTIVE COMPENSATION AND OTHER INFORMATION

Our named executive officers (“NEOs”) for 2024, which consist of our principal executive officer, our next two most highly compensated executive officers who were serving as executive officers as of December 31, 2024, and two additional individuals who served as our executive officers during 2024 but were not serving in such capacity as of December 31, 2024, are:

•

Zachary D. Hornby, Chief Executive Officer, President, and Director;

•

Christian Hassig, Ph.D., Chief Scientific Officer;

•

Klaus Wagner, M.D., Ph.D., our former Chief Medical Officer (whose employment ended on December 29, 2024);

•

Jami Rubin, our former Chief Financial Officer (whose employment ended on October 11, 2024); and

•

Neil Abdollahian, our former Chief Business Officer (whose employment ended on January 10, 2025).

Summary Compensation Table

The primary elements of compensation for our NEOs are base salary, annual performance bonuses, and equity awards. Our NEOs also participate in employee benefit plans and programs that we offer to our other employees, as described below. The following table presents summary information regarding the compensation that was awarded to, earned by, or paid to our NEOs for services rendered during the years ended December 31, 2024 and 2023.


						Non-equity
				Option		incentive plan		All other
		Salary		awards		compensation		compensation		Total
Name and principal position	Year	($)		($)(1)		($)(2)		($)(3)		($)
Zachary D. Hornby	2024		594,558		5,175,279		281,586		3,450		6,054,873
President, Chief Executive Officer, and Director	2023		495,000		1,651,813		222,750		3,300		2,372,863

Christian Hassig, Ph.D.	2024		453,118		1,541,030		158,276		3,450		2,155,874
Chief Scientific Officer	2023		415,000		339,960		145,250		3,300		903,510

Klaus Wagner, M.D., Ph.D.	2024		491,827		1,353,457		—		—		1,845,284
Former Chief Medical Officer	2023		465,840		363,572		163,044		3,300		995,756

Jami Rubin	2024		354,118		1,034,798		—		352,162		1,741,078
Former Chief Financial Officer

Neil Abdollahian	2024		403,680		740,577		—		3,450		1,147,707
Former Chief Business Officer

(1)

With respect to the option awards in 2024, the amounts disclosed represent both the aggregate grant date fair value of the options granted in 2024 as calculated in accordance with Financial Accounting Standards Board Accounting Standards Codification Topic 718 (“ASC 718”) and also include the following incremental fair value associated with the modification in 2024 of the exercise prices of our NEOs’ options in connection with our option repricing in August 2024, also calculated in accordance with ASC 718: $235,666 for Mr. Hornby, $70,290 for Dr. Hassig, $61,404 for Dr. Wagner, $47,124 for Ms. Rubin, and $33,711 for Mr. Abdollahian. With respect to the option awards in 2023, the amounts disclosed represent the aggregate grant date fair value of the award as calculated in accordance with ASC 718 and also include the following incremental fair value associated with the modification in 2023 of the exercise prices of our NEOs’ options in connection with our option repricing in June 2023, also calculated in accordance with ASC 718: $170,293 for Mr. Hornby, $41,722 for Dr. Hassig, and $65,334 for Dr. Wagner. All options are also subject to vesting acceleration under certain circumstances as more fully described in the section titled “Severance and Change in Control Severance Plan.” The amounts in this column do not correspond to the actual value that may be recognized by the NEOs upon vesting of the applicable awards. For a discussion of the assumptions used in calculating the grant date fair value of the awards and the incremental fair value reported in this column, see Notes 2 and 11 to the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2024 filed with the SEC on March 27, 2025.

(2)

The amounts reported represent annual performance bonuses earned with respect to the applicable year.

(3)

The amounts reported represent matching contributions earned by the NEOs under our 401(k) plan ($3,450 for 2024 and $3,300 for 2023). In addition, for Ms. Rubin, the amount includes a severance payout of $345,000 pursuant to our Severance Plan (discussed below in the section titled “Severance and Change in Control Severance Plan”) and $7,162.46 in continued subsidized health benefits following her termination of employment.

Annual Base Salary

We pay our NEOs a base salary to compensate them for their performance of services rendered to us. The base salary payable to each NEO is intended to provide a fixed component of compensation reflecting the executive’s skill set, experience, role, and responsibilities. Base salaries for our NEOs have generally been set at levels deemed necessary to attract and retain individuals with superior talent. We expect that base salaries for our NEOs will be reviewed periodically by our Compensation Committee, with adjustments expected to be made generally in accordance with the considerations described above and to maintain base salaries at competitive levels.

The annual base salaries for our NEOs for 2024 were established in late 2023 by our Compensation Committee in connection with our standard annual review, as well as in April 2024 in connection with the completion of our initial public offering (“IPO”), to further align our NEOs’ cash compensation with market practice.

Effective January 1, 2024, our NEOs’ annual base salaries were increased as follows: Mr. Hornby, from $495,000 to $515,000; Dr. Hassig, from $415,000 to $431,600; Dr. Wagner, from $465,840 to $482,144; Ms. Rubin, from $425,000 to $431,198; and Mr. Abdollahian, from $380,000 to $393,300.

In connection with our IPO, effective April 1, 2024, our NEOs’ annual base salaries were further increased as follows: Mr. Hornby, from $515,000 to $620,000; Dr. Hassig, from $431,600 to $460,000; Dr. Wagner, from $482,144 to $500,000; Ms. Rubin, from $431,198 to $460,000; and Mr. Abdollahian, from $393,300 to $407,000.

Non-Equity Incentive Plan Compensation

In addition to base salaries, our NEOs are eligible to receive annual performance-based cash bonuses, which are designed to provide appropriate incentives to our executives to achieve annual corporate goals and to reward our executives for individual achievement towards these goals. The annual performance-based bonus each NEO is eligible to receive is based on the extent to which we achieve the corporate goals that our Board establishes each year. At the end of the year, our Board reviews our performance against each corporate goal and determines the extent to which we achieved each of our corporate goals.

For 2024, Mr. Hornby was eligible to receive a target annual bonus equal to 55% of his annual base salary, and our other NEOs were eligible to receive target annual bonuses equal to 40% of their respective annual base salaries.

The corporate goals our Board established for 2024 related to product development and pipeline goals, as well as corporate development goals. Bonuses are usually determined and paid in the first quarter of the following year. Based on our performance against the approved company objectives, our Compensation Committee determined to fund the 2024 bonus plan at 90% of the target level.

Actual amounts paid to each NEO for 2024 performance, to the extent such NEOs were eligible for 2024 annual bonus payouts, are set forth in the “Non-equity incentive plan compensation” column of the “Summary Compensation Table” above.

Equity-Based Incentive Awards

Our equity-based incentive awards are designed to align our interests and the interests of our stockholders with those of our employees and consultants, including our NEOs. Our Board and Compensation Committee are responsible for approving equity grants. We typically grant equity awards to new hires upon their commencing employment with us. Generally, our equity awards vest over four years, subject to the employee’s continued employment with us on each vesting date. Option awards are eligible for accelerated vesting on the terms provided in the Severance Plan.

We granted our NEOs stock options during 2024 as part of their total compensation packages.

In February 2024, we granted Mr. Hornby, Dr. Hassig, Dr. Wagner, Ms. Rubin, and Mr. Abdollahian options to purchase 257,207, 76,172, 68,080, 51,420, and 36,852 shares of our common stock, respectively, under our 2018 Equity Incentive Plan (the “2018 Plan”). The options were granted with an exercise price of $8.19 per share and vest over a period of four years in equal monthly installments beginning on the first monthly anniversary of the vesting commencement date, subject to the NEOs continuous service with us as of each vesting date.

In March 2024, in connection with the completion of our IPO, we granted Mr. Hornby, Dr. Hassig, Dr. Wagner, Ms. Rubin, and Mr. Abdollahian options to purchase 162,343, 48,703, 41,745, 32,468, and 23,191 shares of our common stock, respectively, under our 2024 Incentive Award Plan (the “2024 Plan”). The options were granted with an exercise price of $16.00

per share and vest over a period of four years in equal monthly installments beginning on the first monthly anniversary of the vesting commencement date, subject to the NEOs continuous service with us as of each vesting date.

The options granted to our NEOs in 2024 were repriced in August 2024, as discussed below under “Repricing of Outstanding Options.”

Repricing of Outstanding Options

In August 2024, our Compensation Committee approved an option repricing, which was effective on August 19, 2024 (the “Repricing Effective Date”). The repricing applied to options to purchase up to an aggregate of 3,484,346 shares of our common stock with an exercise price per share in excess of the closing price per share of our common stock on the Repricing Effective Date, held by our eligible employees, including our NEOs, that were granted under the 2024 Plan or the 2018 Plan and were outstanding as of the Repricing Effective Date (the “Repriced Options”). As of the Repricing Effective Date, our NEOs held the following aggregate number of Repriced Options: Mr. Hornby, 1,147,242 Repriced Options (with original exercise prices ranging from $4.10 to $16.00); Dr. Hassig, 292,821 Repriced Options (with original exercise prices ranging from $3.71 to $16.00); Dr. Wagner, 316,893 Repriced Options (with original exercise prices ranging from $4.10 to $16.00); Ms. Rubin, 280,553 Repriced Options (with original exercise prices ranging from $4.10 to $16.00); and Mr. Abdollahian, 216,913 Repriced Options (with original exercise prices ranging from $4.10 to $16.00).

As of the Repricing Effective Date, the exercise price of each of the Repriced Options was reduced to $3.56 per share, which was the closing price of our common stock on the Repricing Effective Date; provided, however, that if prior to the Premium End Date (as defined below), a Repriced Option is exercised or an employee’s employment or service with us terminates for any reason other than due to a Qualifying Termination (as defined below), the exercise price per share that applied to the Repriced Option immediately prior to the Repricing Effective Date will apply in lieu of the reduced exercise price. The “Premium End Date” means the earliest of: (1) August 19, 2026, (2) the date immediately prior to the closing of a change in control (as defined in the 2024 Plan), or (3) the date of the employee’s Qualifying Termination. A “Qualifying Termination” means (a) the involuntary termination of the employee’s employment by us due to a reduction in force (and other than for cause (as defined in the 2024 Plan)), subject to the employee’s execution of an effective general release of claims in our favor, (b) the employee’s death, or (c) termination of the employee’s employment by us following the employee’s disability (as defined in the 2024 Plan). Except for the reduction in the exercise prices of the Repriced Options as described above, the Repriced Options retain their existing terms, including their respective original vesting schedules.

Our Board believes that the option repricing with the Premium End Date will provide added incentives to retain and motivate our key contributors, including our NEOs, without incurring the stock dilution resulting from significant additional equity grants to the eligible participants or significant additional cash expenditures resulting from additional cash compensation.

Health and Welfare Benefits; Perquisites

All of our current NEOs are eligible to participate in our employee benefit plans, including our medical, dental, vision, disability, and life insurance plans, in each case on the same basis as all of our other employees. We generally do not provide perquisites or personal benefits to our NEOs, except in limited circumstances. Our Board may elect to adopt qualified or non-qualified benefit plans in the future if it determines that doing so is in our best interests.

401(k) Plan

Our NEOs are eligible to participate in a defined contribution retirement plan that provides eligible employees with an opportunity to save for retirement on a tax advantaged basis. Eligible employees may defer eligible compensation on a pre-tax or after-tax (Roth) basis, up to the statutorily prescribed annual limits on contributions under the Internal Revenue Code of 1986, as amended (the “Code”). Contributions are allocated to each participant’s individual account and are then invested in selected investment alternatives according to the participants’ directions. The 401(k) plan is intended to be qualified under Section 401(a) of the Code with the 401(k) plan’s related trust intended to be tax exempt under Section 501(a) of the Code. As a tax-qualified retirement plan, contributions to the 401(k) plan (except for Roth contributions) and earnings on those contributions are not taxable to the employees until distributed from the 401(k) plan. The 401(k) plan provides for discretionary matching and profit sharing contributions. In 2024, we provided matching contributions equal to 25% of the first 4% of eligible contributions deferred by our employees, not to exceed 1% of an employee’s eligible compensation. Our Board may elect to adopt qualified or nonqualified retirement plans in the future, if it determines that doing so is in our best interests.

Nonqualified Deferred Compensation

We do not maintain nonqualified defined contribution plans or other nonqualified deferred compensation plans. Our Board may elect to provide our officers and other employees with nonqualified defined contribution or other nonqualified deferred compensation benefits in the future if it determines that doing so is in our best interests.

Clawback Policy

We have adopted a Policy for Recovery of Erroneously Awarded Compensation (also known as a clawback policy) that is compliant with the Nasdaq listing rules, as required by the Dodd-Frank Act, and can be accessed in our Annual Report on Form 10-K for the year ended December 31, 2024 filed with the SEC on March 27, 2025.

Equity Award Grant Practices

We have had no program, plan, or practice pertaining to the timing of stock option grants to NEOs coinciding with the release of material non-public information (“MNPI”). Annual grants of stock options to employees are typically approved by our Compensation Committee or our president and chief executive officer pursuant to a delegation of authority from our Compensation Committee in the first quarter of each year as part of our annual compensation cycle. Our Board or Compensation Committee may also approve grants at other times as they deem appropriate, such as the stock option awards granted on March 27, 2024, in connection with the completion of our IPO. The timing of any equity grants to newly-hired employees, or in connection with promotions or other non-routine grants, is generally tied to the event giving rise to the award, although non-executive new hire stock option awards are generally approved at the beginning of the calendar month following the individual’s commencement of employment. For all stock option awards, the exercise price is no less than the closing price of our common stock on the date of the grant.

The following table sets forth information for certain stock options granted to our NEOs during 2024 as required under Item 402(x) of Regulation S-K. In the event a company grants stock options or option-like instruments within the period commencing four business days prior to and ending one business day following the filing by such company of a Form 10-K, Form 10-Q, or Form 8-K containing MNPI, Item 402(x) of Regulation S-K requires tabular disclosure of certain information related to such awards. The table below is being provided because certain of the stock options granted to our NEOs during 2024 were granted within the period commencing four business days prior to and ending one business day following our filing of a Form 10-K, Form 10-Q, or Form 8-K containing MNPI.


Name	Grant Date	Number of Securities Underlying the Award	Exercise Price of the Award at Time of Grant ($) (1)	Grant Date Fair Value of the Award ($)	Percentage Change in the Closing Market Price of the Securities Underlying the Award Between the Trading Day Ending Immediately Prior to the Disclosure of MNPI and the Trading Day Beginning Immediately Following the Disclosure of MNPI
Zachary D. Hornby	3/27/2024	162,343	16.00	2,041,479	(0.66%)
Christian Hassig, Ph.D.	3/27/2024	48,703	16.00	612,445	(0.66%)
Klaus Wagner, M.D., Ph.D.	3/27/2024	41,745	16.00	524,947	(0.66%)
Jami Rubin	3/27/2024	32,468	16.00	408,288	(0.66%)
Neil Abdollahian	3/27/2024	23,191	16.00	291,629	(0.66%)

(1)

This column reflects the exercise price of the options as of the date of grant. These options were repriced on August 19, 2024, as described above. The exercise price of the Repriced Options, after giving effect to the option repricing, and assuming achievement of the Premium End Date, is $3.56.

Outstanding Equity Awards at Fiscal Year-End

The following table presents information regarding the outstanding stock options held by each of our NEOs as of December 31, 2024.


	Option awards
					Number of		Number of
					securities		securities
					underlying		underlying
					unexercised		unexercised		Option
				Vesting	options		options		exercise			Option
		Grant		commencement	exercisable		unexercisable		price			expiration
		date		date	(#)		(#)		($)			date
Zachary D. Hornby		6/10/2020	(1)	6/10/2020		128,205		—		3.12		6/9/2030
		6/7/2021	(1)	6/7/2021		224,357		32,053		3.56	(3)	6/6/2031
		6/13/2023	(1)	6/13/2023		176,724		294,558		3.56	(3)	6/12/2033
		2/15/2024	(1)	2/15/2024		53,580		203,627		3.56	(3)	2/14/2034
		3/27/2024	(1)	3/27/2024		30,439		131,904		3.56	(3)	3/26/2034

Christian Hassig, Ph.D.		12/3/2019	(2)	10/28/2019		38,461		—		3.56	(3)	12/2/2029
		12/2/2020	(1)	1/1/2021		10,042		214		3.56	(3)	12/1/2030
		6/7/2021	(1)	6/7/2021		54,965		7,854		3.56	(3)	6/6/2031
		6/13/2023	(1)	6/13/2023		35,572		59,299		3.56	(3)	6/12/2033
		2/15/2024	(1)	2/15/2024		15,866		60,306		3.56	(3)	2/14/2034
		3/27/2024	(1)	3/27/2024		9,131		39,572		3.56	(3)	3/26/2034

Klaus Wagner, M.D., Ph.D.		2/24/2022	(2)	2/22/2022		72,644		29,919		3.56	(3)	12/13/2032
		12/13/2022	(1)	12/13/2022		4,814		4,820		3.56	(3)	12/12/2032
		6/13/2023	(1)

SEC Form DEF 14A filed by Boundless Bio Inc.