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:

XILIO THERAPEUTICS, 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):

828 Winter Street, Suite 300

Waltham, Massachusetts 02451

NOTICE OF 2026 ANNUAL MEETING OF STOCKHOLDERS

To Be Held on June 10, 2026

Dear Stockholders:

You are cordially invited to attend the 2026 annual meeting of stockholders of Xilio Therapeutics, Inc. to be held on June 10, 2026 at 11:00 a.m., Eastern Daylight Time, virtually at www.virtualshareholdermeeting.com/XLO2026.

At the annual meeting, stockholders will consider and vote on the following matters:

We have elected to provide access to our proxy materials over the internet under the U.S. Securities and Exchange Commission’s, or the SEC’s, “notice and access” rules. We believe that providing our proxy materials over the internet expedites stockholders’ receipt of proxy materials, lowers costs and reduces the environmental impact of our annual meeting. Accordingly, on or about April 28, 2026, we are sending to our stockholders a notice of internet availability of proxy materials, or the notice of availability, instead of a paper copy of our proxy materials.

Only stockholders of record at the close of business on April 16, 2026, the record date for the annual meeting, are entitled to notice of and to vote at the annual meeting or any adjournment or postponement thereof. As noted above, our annual meeting will be a virtual meeting of stockholders, which will be conducted exclusively via the internet as a virtual web conference. You will be able to attend the annual meeting online, vote your shares during the annual meeting and submit questions for consideration during the annual meeting through www.virtualshareholdermeeting.com/XLO2026. Please carefully review the enclosed proxy statement and the notice of availability for additional details.

Your vote is important, and we encourage all stockholders to attend the annual meeting online. Whether or not you plan to attend the annual meeting online, we encourage you to read this proxy statement and submit your proxy or voting instructions as soon as possible by following the instructions in the notice of availability and submitting your proxy by the internet, telephone, or by signing, dating and returning your proxy card or voting instruction form. Please review the instructions on each of youro voting options described in the attached proxy statement. Further information about how to register for and attend the annual meeting online, vote your shares and submit questions for consideration at the meeting is included in the accompanying proxy statement.

Thank you for your ongoing support and continued interest in Xilio Therapeutics, Inc.

Waltham, Massachusetts

April 28, 2026

TABLE OF CONTENTS

828 Winter Street, Suite 300

Waltham, Massachusetts 02451

(857) 524-2466

PROXY STATEMENT

2026 ANNUAL MEETING OF STOCKHOLDERS

To Be Held on June 10, 2026

INFORMATION CONCERNING SOLICITATION AND VOTING

This proxy statement and the enclosed proxy card are being furnished in connection with the solicitation of proxies by the board of directors of Xilio Therapeutics, Inc., or Xilio, for use at the annual meeting of stockholders, or annual meeting, to be held virtually on June 10, 2026 at 11:00 a.m., Eastern Daylight Time, and at any adjournment thereof.

The annual meeting will be held exclusively online as a virtual meeting at www.virtualshareholdermeeting.com/XLO2026. There will not be a physical meeting location, and stockholders will not be able to attend the annual meeting in person. Further information about how to attend the annual meeting online, vote your shares and submit questions during the meeting is included in this proxy statement.

In this proxy statement, unless expressly stated or the context otherwise requires, references to “Xilio,” “the company,” “we,” “us,” “our” and similar terms refer to Xilio Therapeutics, Inc. References to our website are inactive textual references only, and the contents of our website are not incorporated by reference into this proxy statement.

We are making this proxy statement, the related proxy card and our 2025 annual report to stockholders available to stockholders on or about April 28, 2026. All properly submitted proxies will be voted in accordance with the instructions contained in those proxies. If no instructions are specified, the shares represented by the proxies will be voted in accordance with the recommendation of our board of directors. If you are a stockholder of record, you may change your vote or revoke your proxy at any time before it is exercised at the meeting by following the instructions set forth in this proxy statement.

Important Notice Regarding the Availability of Proxy Materials

This proxy statement and our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, as filed with the SEC, are available for viewing, printing and downloading at www.proxyvote.com. In addition, this proxy statement and our Annual Report on Form 10-K are available on the SEC’s website at www.sec.gov and the “Investors & Media - Financials & Filings - SEC Filings” section of our website, which is located at https://ir.xiliotx.com. A printed copy of our Annual Report on Form 10-K, excluding exhibits, will be furnished without charge to any stockholder upon written request to Xilio Therapeutics, Inc., 828 Winter Street, Suite 300, Waltham, Massachusetts 02451 or by calling 1-800-579-1639, e-mailing sendmaterial@proxyvote.com and including your control number in the subject line, or by submitting a request at www.proxyvote.com.

EXPLANATORY NOTE

Unless otherwise indicated, all share amounts and per share amounts have been adjusted retroactively in this proxy statement to give effect to the 1-for-14 reverse stock split of our common stock effected on March 13, 2026.

IMPORTANT INFORMATION ABOUT THE ANNUAL MEETING AND VOTING

Why Did I Receive These Proxy Materials?

We have made these materials available to you on the internet in connection with the solicitation of proxies for use at our 2026 annual meeting of stockholders to be held online on Wednesday, June 10, 2026 at 11:00 a.m., Eastern Daylight Time, at www.virtualshareholdermeeting.com/XLO2026. As a holder of common stock, you are invited to attend the annual meeting online and are requested to vote on the items of business described in this proxy statement. This proxy statement includes information that we are required to provide to you under applicable SEC rules and regulations and that is designed to assist you in voting your shares.

Purpose of the Annual Meeting

At the annual meeting, our stockholders will consider and vote on the following matters:

As of the date of this proxy statement, we are not aware of any business to come before the meeting other than the first three items noted above. Should any other business come before the annual meeting, the persons named on the company’s proxy card will have discretionary authority to vote the shares represented by such proxies. If you hold shares through a broker, bank or other nominee as described below, we expect that they will not be able to vote your shares on any other business that comes before the annual meeting unless they receive instructions from you with respect to such matter.

Board of Directors Recommendation

Our board of directors unanimously recommends that you vote:

Availability of Proxy Materials

The proxy materials, including this proxy statement, a proxy card and our 2025 Annual Report on Form 10-K are available for viewing, printing and downloading at www.proxyvote.com. On or about April 28, 2026, we will mail the notice of availability to stockholders, unless they have requested a printed copy of proxy materials. If you would like to receive a paper copy of our proxy materials, you should follow the instructions for requesting paper materials in the notice of availability. To facilitate delivery prior to the annual meeting, please make your request prior to May 27, 2026.

Who Can Vote at the Annual Meeting?

Only stockholders of record at the close of business on April 16, 2026, the record date for the annual meeting, are entitled to notice of and to vote at the annual meeting or any adjournment or postponement thereof. As of the record date, there were 5,982,839 shares of our common stock outstanding and entitled to vote at the annual meeting. Each share of common stock that you own as of the record date is entitled to one vote on each matter properly brought before the annual meeting.

Difference Between a “Stockholder of Record” and a Beneficial Owner of Shares Held in “Street Name”

How to Virtually Attend the Annual Meeting

The annual meeting will start at 11:00 a.m., Eastern Daylight Time, on June 10, 2026 and will be a virtual meeting of stockholders where stockholders will participate by accessing a website using the internet. There will not be a physical meeting location. We believe that hosting a virtual meeting will facilitate stockholder attendance and participation at our annual meeting by enabling stockholders to participate from any location around the world. We have designed the virtual annual meeting to provide the same rights and opportunities to participate as stockholders would have at an in-person meeting, including the right to vote and ask questions during the meeting through the virtual meeting platform.

Stockholders of record as of April 16, 2026 will be able to attend and participate in the annual meeting by accessing www.virtualshareholdermeeting.com/XLO2026. You may log into the virtual meeting starting at 10:45 a.m., Eastern Daylight Time, on the day of the meeting. To join the annual meeting, you will need to have your 16-digit control number, which is included on your notice of availability and your proxy card. In the event that you do not have a control number, please contact your broker, bank, or other nominee as soon as possible so that you can be provided with a control number and gain access to the annual meeting. Stockholders will also have the opportunity to submit questions during the annual meeting through www.virtualshareholdermeeting.com/XLO2026. A technical support telephone number will be posted on the log-in page that you can call if you encounter any difficulties accessing the virtual meeting during the check-in or during the meeting.

How to Vote and Voting Deadlines

If you are the stockholder of record of your shares, meaning that your shares are registered in your name in the records of our transfer agent, Computershare Trust Company, N.A., and not in the name of a bank, brokerage firm or other nominee, you can vote your shares by proxy prior to the annual meeting or online during the annual meeting as follows:

If the annual meeting is adjourned or postponed, the foregoing deadlines may be extended.

If your shares are held in “street name,” meaning your shares are held for your account by an intermediary, such as a bank, brokerage firm or other nominee, then you are deemed to be the beneficial owner of your shares, and the bank, brokerage firm or other nominee that actually holds the shares for you is the record holder and is required to vote the shares it holds on your behalf according to your instructions. The proxy materials, as well as voting and revocation instructions, should have been forwarded to you by the bank, broker or other nominee that holds your shares. In order to have your broker or other nominee vote your shares, you will need to follow the instructions that your bank, broker or other nominee provides you. The voting deadlines and availability of telephone and internet voting for beneficial owners of shares held in “street name” will depend on the voting processes of the bank, broker or other nominee that holds your shares. Therefore, we urge you to carefully review and follow the voting instruction card and any other materials that you receive from that organization.

Under applicable stock exchange rules, banks, brokerage firms and other nominees may use their discretion to vote “uninstructed” shares (i.e., shares of record held by banks, brokers or other nominees, but with respect to which the beneficial owner of such shares has not provided instructions on how to vote on a particular proposal) with respect to matters that are considered to be “discretionary,” but not with respect to “non-discretionary” matters. With respect to non-discretionary items for which you do not give your broker voting instructions, your shares will be treated as broker non-votes. A “broker non-vote” occurs when shares held by a bank, brokerage firm or other nominee are not voted with respect to a particular proposal because the bank, brokerage firm or other nominee does not have or did not exercise discretionary authority to vote on the matter and has not received voting instructions from its client. For a discussion of how broker non-votes will be treated, see the discussion under “Votes Required to Approve Each Proposal.”

Regardless of whether your shares are held in street name, you are welcome to attend the annual meeting online. To do so, you will need your control number included on your notice of availability, proxy card or voting instruction form in order to demonstrate proof of beneficial ownership. However, you may not vote shares held in street name at the annual meeting, unless you obtain a legal proxy from your bank, brokerage firm or other nominee issued in your name giving you the right to vote your shares.

Even if you plan to attend the annual meeting online, we urge you to vote your shares by proxy in advance of the annual meeting so that if you become unable to attend the annual meeting, your shares will be voted as directed by you.

Can I Vote My Shares by Filling Out and Returning the Notice of Internet Availability of Proxy Materials?

No. The notice of availability and proxy card contain instructions on how to vote by proxy via the internet, by telephone, by requesting and returning a paper proxy card, or by voting online while virtually attending the annual meeting.

How Do I Submit a Question at the Annual Meeting?

If you wish to submit a question during the annual meeting, beginning at 10:45 a.m., Eastern Daylight Time, on June 10, 2026, you may log into the virtual meeting platform using the unique link provided to you via e-mail following the completion of your registration at www.virtualshareholdermeeting.com/XLO2026 and follow the instructions there. Our virtual meeting will be governed by our Rules of Conduct and Procedures which will be posted at www.virtualshareholdermeeting.com/XLO2026 during the annual meeting. The Rules of Conduct and Procedures will address the ability of stockholders to ask questions during the meeting, including rules on permissible topics and rules for how questions and comments will be recognized and disclosed to meeting participants.

May I See a List of Stockholders Entitled to Vote as of the Record Date?

A complete list of registered stockholders as of the close of business on the record date will be available for inspection by our stockholders of record at least 10 days prior to the annual meeting during normal business hours at our headquarters at 828 Winter Street, Suite 300, Waltham, MA 02451. If you are unable to inspect this list in person, please contact our Corporate Secretary by mail at Xilio Therapeutics, Inc., 828 Winter Street, Suite 300, Waltham, Massachusetts 02451, Attention: Corporate Secretary, or by e-mail at investors@xiliotx.com to request such list. When making such request, please ensure that you have your notice of availability or proxy card available so that you can prove that you are a registered stockholder.

Quorum

A majority of our shares of common stock outstanding as of the record date must be present or represented by proxy to constitute a quorum and hold the annual meeting. For purposes of determining whether a quorum exists, we count as present any shares that are voted over the internet, by telephone, by mail or that are represented at the virtual annual meeting. Further, for purposes of establishing a quorum, we will count as present shares that a stockholder holds even if the stockholder votes to abstain or only votes on one of the proposals. In addition, because we expect that brokers, banks or other nominees will be able to vote on at least one proposal, we expect that the shares held by these entities will be counted for purposes of determining whether a quorum is present. If a quorum is not present, we expect to adjourn the annual meeting until we obtain a quorum. Votes cast by proxy will be tabulated by the inspector of election appointed for the annual meeting, who will also determine whether a quorum is present.

Votes Required to Approve Each Proposal

Although stockholder approval of our audit committee’s selection of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026 is not required, we believe that it is advisable to give stockholders an opportunity to ratify this selection. If this proposal is not approved at the annual meeting, our audit committee will reconsider its selection of Ernst & Young LLP as our independent registered public accounting firm for the year ending December 31, 2026.

Revoking a Proxy; Changing Your Vote

If you are a stockholder of record, you may revoke your proxy and change your vote at any time before the vote is taken at the annual meeting. To do so, you must do one of the following:

If your shares are held in “street name,” you may submit new voting instructions by contacting your bank, broker or other nominee holding your shares. You may also vote online during the annual meeting, which will have the effect of revoking any previously submitted voting instructions, if you obtain a legal proxy from the organization that holds your shares and follow the procedures described in the “How to Vote and Voting Deadlines” section above.

Your virtual attendance at the annual meeting, without voting online during the annual meeting, will not automatically revoke your proxy.

Costs of Proxy Solicitation

We will bear the costs of soliciting proxies and tabulating your votes. In addition to solicitation by mail, our directors, officers and employees may solicit proxies personally, by telephone, e-mail or in person without additional compensation for the solicitation, but these directors, officers and employees may be reimbursed for out-of-pocket expenses incurred in connection with the solicitation. Copies of solicitation materials will be furnished to brokerage firms, fiduciaries, and other custodians who hold shares of our common stock of record for beneficial owners for forwarding to such beneficial owners. We may reimburse banks, brokers and other holders of record for their reasonable, out-of-pocket expenses for forwarding these proxy materials to beneficial owners.

Voting Results

We plan to announce preliminary voting results at the annual meeting and expect to report final voting results in a Current Report on Form 8-K to be filed with the SEC within four business days following the annual meeting.

Whom Should I Contact With Any Additional Questions?

If you hold your shares directly or have additional questions about the annual meeting, please contact us at Xilio Therapeutics, Inc., 828 Winter Street, Suite 300, Waltham, Massachusetts 02451, Attn: Investor Relations, or by e-mail at investors@xiliotx.com.

If your shares are held in street name, please call the telephone number provided on your voting instruction form or contact your bank, brokerage firm or other nominee directly.

PROPOSAL NO. 1-ELECTION OF DIRECTORS

In accordance with the terms of our certificate of incorporation, our board of directors is divided into three classes (Class I, Class II and Class III), with members of each class serving staggered three-year terms. Directors in each class are elected at the annual meeting of stockholders held in the year in which the term for their class expires and hold office for a three-year term and until their resignation or removal or their successors are duly elected and qualified. In accordance with our certificate of incorporation and our second amended and restated bylaws, or our bylaws, our directors may fill existing vacancies on the board of directors.

The term of office of our Class II directors, Akintunde Bello, Ph.D., Daniel Curran, M.D., Robert Ross, M.D. and Yuan Xu, Ph.D., will expire at the 2026 annual meeting of stockholders. Our board of directors has nominated Akintunde Bello, Daniel Curran, Robert Ross and Yuan Xu for election as Class II directors at the annual meeting. Drs. Bello, Curran, Ross and Xu have indicated a willingness to continue to serve as directors, if elected. If Drs. Bello, Curran, Ross or Xu is elected at the 2026 annual meeting of stockholders, such individual will be elected to serve for a three-year term that will expire at our 2029 annual meeting of stockholders and until such individual’s successor is elected and qualified.

If no contrary indication is made, proxies in the accompanying form will be voted for Drs. Bello, Curran, Ross and Xu, or, in the event that any of Drs. Bello, Curran, Ross or Xu is not a candidate or is unable to serve as a director at the time of the election (which is not currently expected), for any nominee who is designated by our board of directors to fill the vacancy.

If all four Class II directors are elected at the 2026 annual meeting of stockholders, the board of directors will consist of three directors in Class I, four directors in Class II, and two directors in Class III. For the sole purpose of achieving an equal balance of membership among the three classes of the board of directors, and assuming all four Class II directors are elected, Dr. Curran has indicated he is willing to resign from the board of directors following the 2026 annual meeting of stockholders, at which time the board of directors would appoint him to serve as a Class III director, with a term expiring at the 2027 annual meeting of stockholders. Following this rebalancing, the board of directors is expected to consist of three directors in each of Classes I, II and III.

Information Regarding Directors

Set forth below are the names and certain information for each member of our board of directors as of April 15, 2026, including the nominees for election as Class II directors. The information presented includes each director’s and nominee’s principal occupation and business experience for the past five years, and the names of other public companies of which he or she has served as a director during the past five years. The information presented below regarding the specific experience, qualifications, attributes and skills of each director and nominee led our board of directors to conclude that he or she should serve as a director. In addition, we believe that all of our directors and nominees possess the attributes or characteristics described in “-Director Nomination Process” that the nominating and corporate governance committee expects of each director. There is no arrangement or understanding between any of our directors and any other person or persons pursuant to which he or she was or is to be selected as a director.

Class II Director Nominees-For a Three-Year Term Expiring at the 2029 Annual Meeting of Stockholders

Akintunde Bello, Ph.D., has served as a member of our board of directors since June 2025. He has more than 25 years of oncology drug development and leadership experience, with deep expertise in early translational medicine and clinical pharmacology across complex biologics and immunotherapies. Dr. Bello held roles of increasing responsibility at Bristol Myers Squibb Company, or BMS, a pharmaceutical company, since October 2018, and most recently served as senior vice president, head of clinical pharmacology, pharmacometrics and bioanalysis from January 2015 until his retirement in January 2025. Previously, Dr. Bello spent more than a decade at Pfizer Inc., or Pfizer, from October 2003 to January 2015 where he was responsible for overseeing clinical pharmacology for Pfizer's late-stage oncology development programs. Dr. Bello received a B.Sc. in biomedical sciences from Portsmouth Polytechnic, an M.Sc. in instrumentation and analytical science from University of Manchester and a Ph.D. in pharmaceutical sciences from King's College, University of London. We believe Dr. Bello is qualified to serve on our board of directors because of his experiences as a pharmaceutical executive with more than 25 years of experience.

Daniel Curran, M.D., has served as a member of our board of directors since December 2020. He has more than 20 years of pharmaceutical experience in strategy, business development, project leadership and development roles. Dr. Curran currently serves as a managing partner at Mountainfield Venture Partners, LLC, a company-creation firm, since March 2024. Previously, Dr. Curran held roles of increasing responsibility at Takeda Pharmaceutical Company Ltd., or Takeda, a pharmaceutical company, since 2008, and most recently served as a senior vice president and the head of

the rare genetics and hematology therapeutic area unit from January 2019 until December 2023. Prior to Takeda, he served as vice president, corporate development at Millennium Pharmaceuticals, Inc., or Millennium, a wholly owned subsidiary of Takeda, from 1999 to 2008. Prior to Millennium, Dr. Curran held a business development role in the product planning and acquisition group at DuPont Merck Pharmaceuticals, a pharmaceutical company. Dr. Curran currently serves as a member on the boards of directors of Catalyst Pharmaceuticals, Inc., a public biotechnology company, and ALX Oncology Holdings Inc., a public biotechnology company. Dr. Curran received a B.S. in chemistry from King’s College, an M.B.A. from The Wharton School of the University of Pennsylvania and an M.D. from the University of Pennsylvania School of Medicine. We believe Dr. Curran is qualified to serve on our board of directors because of his diverse experience in the life sciences industry.

Robert Ross, M.D., has served as a member of our board of directors since June 2022. Dr. Ross currently serves as chief executive officer, president and a member of the board of directors of Clasp Therapeutics, Inc., or Clasp, a private biotechnology company, since November 2023. Prior to Clasp, Dr. Ross served as chief executive officer and a member of the board of directors of Surface Oncology, Inc., or Surface, a biotechnology company, from April 2021 until its acquisition by Coherus Biosciences, Inc. in September 2023. Dr. Ross also served as Surface’s chief medical officer from October 2016 to April 2021. Before Surface, Dr. Ross served as the head of oncology at bluebird bio, Inc., or bluebird bio, and earlier served in roles as senior vice president of clinical development and pharmacovigilance and vice president of clinical development. Prior to bluebird bio, Dr. Ross worked at Genentech and Infinity Pharmaceuticals, Inc. Dr. Ross was a Fellow in Medical Oncology and a faculty member at the Dana Farber Cancer Institute, or DFCI, from 2003 to 2007, and then he maintained a clinical practice at DFCI until 2015. In addition to serving on the board of directors of Clasp, Dr. Ross currently serves on the board of directors of Obsidian Therapeutics, Inc., a private biotechnology company. Dr. Ross received a B.S. in biological sciences and a B.A. in philosophy from Stanford University, an M.S. in medical science from Harvard Medical School and an M.D. from Columbia University College of Physicians and Surgeons. He completed his residency training in Internal Medicine at the University of California, San Francisco. We believe Dr. Ross is qualified to serve on our board of directors because of his experience as a biopharmaceutical executive with more than 25 years of experience and his diverse experience in the life sciences industry.

Yuan Xu, Ph.D., has served as a member of our board of directors since January 2022. Dr. Xu served as chief executive officer at Legend Biotech Corporation, or Legend Biotech, a biotechnology company, from March 2018 to August 2020. In this capacity, she played a leading role in Legend Biotech’s initial public offering, global clinical development of Legend Biotech’s autologous CAR T-cell therapy CARVYKTI® (ciltacabtagene autoleucel) and a strategic partnership with Janssen Biotech, Inc. Prior to joining Legend Biotech, she served as senior vice president at Merck & Co., Inc., or Merck, from August 2015 to August 2017, where she led discovery, preclinical and technical development, and manufacturing for Merck’s biologics and vaccines subdivision. Prior to that, Dr. Xu served as general manager and vice president of biologics at Gilead Sciences, or Gilead, from March 2014 to August 2015, where she led biologics and vaccines development and oversaw all operational aspects of Gilead’s Oceanside manufacturing facility as site head. Prior to Gilead, Dr. Xu served as vice president at Novartis and led several functions in the U.S. and Europe, including the biotherapeutics development unit focusing on innovative medicines. Earlier in her career, Dr. Xu held positions of increasing responsibility at Amgen Inc., Chiron, Inc., GlaxoSmithKline PLC and Genentech Inc. Dr. Xu currently serves as a member of the board of directors of Fate Therapeutics, Inc., a public biotechnology company, and previously served as a member of the board of directors of Akero Therapeutics, Inc., a public biotechnology company, from April 2021 until its acquisition by Novo Nordisk A/S in December 2025. Dr. Xu received a B.S. in biochemistry from Nanjing University and a Ph.D. in biochemistry from the University of Maryland, and she completed her post-doctoral training in virology and gene therapy at the University of California, San Diego. We believe Dr. Xu is qualified to serve on our board of directors because of her experience as a biopharmaceutical executive with more than 25 years of experience.

OUR board of directors recommends voting “FOR” the election of Akintunde bello, daniel curran, robert ross and yuan xu TO serve as Class II directors for a three-year term ending at the annual meeting of stockholders to be held in 2029.

Class III Directors-Term Expiring at the 2027 Annual Meeting of Stockholders

Aoife Brennan, M.D., has served as a member of our board of directors since June 2024. Dr. Brennan has over 16 years of industry leadership and drug development experience and currently serves as chief executive officer, president and a member of the board of directors of Climb Bio, Inc. (formerly Eliem Therapeutics, Inc.), or Climb Bio, since June 2024. Prior to Climb Bio, Dr. Brennan served as chief executive officer, president and a member of the board of directors of Synlogic, Inc., or Synlogic, from October 2018 until March 2024, and previously served as its chief medical officer from September 2016 until October 2018. Prior to joining Synlogic, Dr. Brennan was vice president and head of the Rare Disease Innovation Unit at Biogen Inc., where she was responsible for research and development for programs ranging from preclinical to commercial-stage within Biogen’s rare disease portfolio. Dr. Brennan also currently serves on the board of directors of Cerevance, LLC, a private pharmaceutical company. Dr. Brennan served as a member of the boards of directors of FibroGen, Inc., a public biopharmaceutical company, from August 2020 to June 2025 and RA Pharmaceuticals, Inc., a public pharmaceutical company, from September 2018 to April 2020. Dr. Brennan received her medical degree from Trinity College in Dublin, Ireland and completed her post-graduate training in internal medicine, endocrinology and metabolism at the Royal College of Physicians in Ireland. In addition, she completed post-doctoral training in clinical research and metabolism at the Beth Israel Deaconess Medical Center in Boston and is a graduate of the Harvard Medical School Scholars in Clinical Science Program. We believe Dr. Brennan is qualified to serve on our board of directors because of her extensive experience with drug development, executive leadership, and prior board experience.

Cheryl Blanchard, Ph.D., has served as a member of our board of directors since April 2026. Dr. Blanchard also currently serves as the executive chair of the board of directors of Anika Therapeutics, Inc., or Anika, a public biotechnology and medical technology company, a position she has held since February 2026, and she formerly served as the president and chief executive officer of Anika between February 2020 and January 2026. In addition, Dr. Blanchard is currently the principal of Blanchard Consulting, LLC, a company she founded in 2012. Before Anika, Dr. Blanchard served as president and chief executive officer of Microchips Biotech, Inc., a biotechnology company, from July 2014 to November 2019 until its acquisition by Daré Bioscience, Inc., or Daré, a public biopharmaceutical company. Earlier in her career, Dr. Blanchard held roles of increasing responsibility at Zimmer, Inc.(now Zimmer Biomet Holdings, Inc.), a public medical technology company, and Southwest Research Institute. Dr. Blanchard has served on the board of directors of Surgicure Technologies, Inc., a private medical device company, since August 2025, and Lumicell, Inc., a private biotechnology company, since February 2026. Dr. Blanchard previously served on the boards of directors of Vigil Neuroscience, Inc., a public biotechnology company, from November 2020 until its acquisition by Sanofi in August 2025, and Daré from November 2019 to June 2024. Dr. Blanchard received a B.S. in ceramic engineering with a minor in mathematics from Alfred University and an M.S. and Ph.D. in materials science and

engineering from the University of Texas in Austin. Dr. Blanchard is a member of the National Academy of Engineering. We believe Dr. Blanchard is qualified to serve on our board of directors because of her diverse experience in the life sciences and medical technology industry.

Class I Directors-Term Expiring at the 2028 Annual Meeting of Stockholders

René Russo, Pharm.D., has served as our chief executive officer and as a member of our board of directors since May 2019 and served as our president from May 2021 to August 2022 and since September 2023. Dr. Russo served as entrepreneur-in-residence at New Enterprise Associates, a venture capital firm, from November 2018 to May 2019. Prior to that, she served as president and chief executive officer of Arsanis, Inc., or Arsanis, a biopharmaceutical company, from May 2016 to December 2018, and as its chief development officer from June 2015 to May 2016. Prior to joining Arsanis, Dr. Russo served in various roles of increasing responsibility over an 11-year period, culminating in her serving as vice president, global medical affairs, at Cubist Pharmaceuticals, Inc., or Cubist, a pharmaceutical development company, focused on the development and commercialization of infectious disease therapeutics, from 2004 until its acquisition by Merck Research Laboratories, a healthcare company, in May 2015. Prior to Cubist, Dr. Russo held R&D roles at Bristol-Myers Squibb Company from 1999 to 2004, where she contributed to the successful development and global commercialization of multiple therapeutics. Dr. Russo served as chair of the board of directors of Invivyd, Inc. (formerly, Adagio Therapeutics, Inc.), a biotechnology company that she co-founded, from July 2020 to June 2022. Additionally, she served as a member of the board of directors of Arsanis from May 2016 to March 2019 and, following its merger with X4 Pharmaceuticals, Inc., or X4 Pharmaceuticals, served as a member of the board of directors of X4 Pharmaceuticals from March 2019 to November 2021. Dr. Russo currently serves as executive chair of Ropirio Therapeutics, a private biotechnology company, on the board of directors of PRxCision, Inc., a private healthcare technology company, and on the supervisory board of Leyden Laboratories B.V., a private biopharmaceutical company. Prior to joining the biotechnology industry, Dr. Russo held clinical positions at Robert Wood Johnson University Hospital and Princeton Hospital. Dr. Russo received her Pharm.D. and B.S. from Rutgers University and completed a post-doctoral fellowship in infectious diseases with Bristol-Myers Squibb. We believe Dr. Russo is qualified to serve on our board of directors because of her expertise and experience as our president and chief executive officer and her expertise in clinical development and commercialization of therapeutics in the life sciences industry.

Sara M. Bonstein has served on our board of directors since August 2021 and has served as chair of our board of directors since January 2026. Ms. Bonstein has more than two decades of operational and financial leadership in the life sciences industry and has served as chief financial officer of Insmed, Inc., or Insmed, a biopharmaceutical company, since January 2020, where she is responsible for Insmed’s key financial functions, including accounting, financial planning and analysis, procurement, and investor relations. Prior to joining Insmed, she served as chief financial officer and chief operating officer of OncoSec Medical Incorporated, a biotechnology company, from May 2018 to January 2020 and as the chief financial officer at Advaxis, Inc., or Advaxis, a biotechnology company, from February 2014 to April 2018. In these roles, Ms. Bonstein has led multiple capital markets and licensing transactions, while establishing strong financial controls, streamlined business operations, and building high performing teams. Prior to Advaxis, Ms. Bonstein served in various finance roles of increasing responsibility, including at Eli Lilly & Company and Johnson & Johnson, or J&J. Ms. Bonstein also serves on the board of directors of Latigo Biotherapeutics, Inc., a private biopharmaceutical company, and previously served on the board of directors of scPharmaceuticals Inc., a public pharmaceutical company, from July 2020 until its acquisition by MannKind Corporation in October 2025. She holds a B.S. in finance from The College of New Jersey and an M.B.A. from Rider University. We believe Ms. Bonstein is qualified to serve on our board of directors because of her experience as a senior executive of several life sciences companies, including her finance and operations expertise and knowledge of the life sciences industry.

James Shannon, M.D., has served as a member of our board of directors since June 2024. Dr. Shannon has more than 30 years of drug development and leadership experience. From 2012 until his retirement in 2015, Dr. Shannon served as the chief medical officer of GlaxoSmithKline PLC. Prior to that, Dr. Shannon spent more than a decade with Novartis, including as global head of pharma development, where he was responsible for all of Novartis’ development activities, from preclinical through Phase 4 clinical development, and oversaw an annual development budget of approximately $4 billion. Dr. Shannon currently serves as chair of the board of directors of MannKind Corporation, a public biopharmaceutical company, ProQR Therapeutics N.V., a public biotechnology company, and Kyowa Kirin (NA), a private biopharmaceutical company and subsidiary of Kyowa Kirin Co., Ltd. Dr. Shannon also serves on the board of directors of myTomorrows, a private health technology company, and the supervisory board of Leyden Laboratories B.V., a private biopharmaceutical company. Dr. Shannon previously served on the board of directors of Horizon Therapeutics plc, a public biopharmaceutical company. Dr. Shannon is trained in Medicine and Cardiology and received his undergraduate degree and M.D. from Queen’s University in Belfast, Northern Ireland. Dr. Shannon is also a Member of the Royal College of Physicians (UK). We believe Dr. Shannon is qualified to serve on our board of directors because of his extensive experience in the life sciences and pharmaceutical industry.

PROPOSAL NO. 2-RATIFICATION OF THE SELECTION OF

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

Our audit committee has selected the firm of Ernst & Young LLP, an independent registered public accounting firm, as independent auditors for the fiscal year ending December 31, 2026. Although stockholder approval of our audit committee’s selection of Ernst & Young LLP is not required by law, our board of directors believes that it is advisable to give stockholders an opportunity to ratify this selection. If this proposal is not approved at the annual meeting, our audit committee will consider whether it is appropriate to select another independent registered public accounting firm. Even if the selection is ratified, the audit committee in its discretion may select a different registered public accounting firm at any time during the year if it determines such a change would be in the best interests of the company and our stockholders.

Representatives of Ernst & Young LLP are expected to be present at the annual meeting online and will have the opportunity to make a statement, if they desire to do so, and will be available to respond to appropriate questions from our stockholders.

Audit Fees and Services

Pre-Approval Policy and Procedures

Our audit committee has adopted policies and procedures relating to the approval of all audit and non-audit services that are to be performed by our independent registered public accounting firm. This policy provides that we will not engage our independent registered public accounting firm to render audit or non-audit services unless the service is specifically approved in advance by our audit committee, or the engagement is entered into pursuant to the pre-approval procedure described below.

From time to time, our audit committee may pre-approve specified types of services that are expected to be provided to us by our independent registered public accounting firm during the next fiscal quarter. Any such pre-approval is detailed as to the particular service or type of services to be provided and is also generally subject to a maximum dollar amount.

During our 2025 and 2024 fiscal years, no services were provided to us by Ernst & Young LLP other than in accordance with the pre-approval policies and procedures described above.

OUR board of directors recommends voting “FOR” the RATIFICATION OF THE SELECTION of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026.

PROPOSAL NO. 3-APPROVAL OF OUR AMENDED AND RESTATED 2021 STOCK INCENTIVE PLAN

Our board of directors believes that stock-based incentive awards can play an important role in the success of our company by encouraging and enabling our employees, officers and non-employee directors whose judgment, initiative, and efforts we largely depend upon for the successful conduct of our business to acquire an ownership interest in our company. Our board of directors believes that providing such persons with a direct stake in our company assures closer alignment of the interests of such individuals with ours and our stockholders, thereby stimulating their efforts on our behalf and strengthening their desire to remain with us. Furthermore, we compete for talent in a highly competitive environment and equity awards are key tools used to attract and retain employees.

On March 24, 2026, as recommended by our compensation committee, our board of directors approved, subject to and contingent on the approval by the stockholders of the company, the amendment and restatement of the Xilio Therapeutics, Inc. 2021 Stock Incentive Plan, which as amended and restated, we refer to as the Amended and Restated 2021 Plan. The Amended and Restated 2021 Plan amends the evergreen provision in the current Xilio Therapeutics, Inc. 2021 Stock Incentive Plan, which we refer to as the Original 2021 Plan, to provide that the number of shares of common stock underlying the company’s outstanding prefunded warrants shall be added to the number of shares of outstanding common stock for purposes of calculating the annual evergreen increase. The Amended and Restated 2021 Plan is attached as Appendix A to this proxy statement. Appendix A is marked to show the proposed changes to the Original 2021 Plan.

All share and per share amounts included in the Amended and Restated 2021 Plan and described below have been adjusted to reflect the 1-for-14 reverse stock split of our common stock, which became effective on March 13, 2026, or the Reverse Stock Split, which adjustments are purely proportional to reflect the Reverse Stock Split, effected in accordance with the terms of the Original 2021 Plan and do not require stockholder approval. No other changes are being made to the Original 2021 Plan, and we are not otherwise requesting an increase in the shares available for the grant of awards under the Original 2021 Plan.

If the Amended and Restated 2021 Plan is not approved by our stockholders, the Original 2021 Plan will continue in its current form without the change to the evergreen provision; however, the Original 2021 Plan will be updated to reflect the Reverse Stock Split as described above.

We intend to utilize the Amended and Restated 2021 Plan as we have utilized the Original 2021 Plan to date; specifically, to grant equity awards to our employees and non-employee directors, and on a limited basis to consultants or advisors in order to incentivize, retain and reward those who are critical to our success. As more fully described below, our compensation committee developed the amendment to the evergreen provision in the Amended and Restated 2021 Plan after considering the projected annual equity grants to our employees and non-employee directors and an assessment of the dilution from the share reserve that our stockholders would find acceptable. If stockholders approve the Amended and Restated 2021 Plan, subject to adjustment in the event of future stock splits and similar events, the maximum number of shares of common stock available for issuance under the Amended and Restated 2021 Plan will be equal to the sum of: (1) 875,208 (which number is the sum of the initial reserve under the Original 2021 Plan and each annual evergreen increase from January 1, 2022 to January 1, 2026); plus (2) such additional number of shares of common stock (up to 283,359 shares) as is equal to the sum of (x) the number of shares of common stock that were reserved for issuance under the Xilio Therapeutics, Inc. 2020 Stock Incentive Plan, as amended, or the 2020 Plan, that were available for grant under the 2020 Plan immediately prior to the effectiveness of the registration statement for the company’s initial public offering, which we refer to as the initial effective date, and (y) the number of shares of common stock subject to awards, whether granted under the 2020 Plan or outside of the 2020 Plan prior to the initial effective date, which awards expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by the company at their original issuance price pursuant to a contractual repurchase right and that, prior to the initial effective date, would have become available for issuance under the 2020 Plan (subject, however, in the case of incentive stock options, to any limitations of the Internal Revenue Code of 1986, as amended, or the Code); plus (3) an annual increase to be added on the first day of each fiscal year, commencing on January 1, 2027 and continuing for each fiscal year until, and including, January 1, 2031, equal to the lesser of (i) 5% of the sum of (a) the number of outstanding shares of common stock on such date and (b) the number of shares of common stock subject to prefunded warrants issued by the company and outstanding as of such date, and (ii) the number of shares of common stock determined by the board of directors. The Amended and Restated 2021 Plan would only affect future annual increases to our share reserve starting in 2027, and would not retroactively affect annual increases effected before the approval of the Amended and Restated 2021 Plan, The Amended and Restated 2021 Plan includes several features that are consistent with protecting the interests of our stockholders and sound corporate governance practices, as described below.

We have relied on the inducement grant exception under Nasdaq Listing Rule 5635(c)(4) to grant nonstatutory stock options, or Inducement Awards, under the Xilio Therapeutics, Inc. Second Amended and Restated 2022 Inducement Stock Incentive Plan, or the 2022 Inducement Plan, to our newly hired employees who are eligible under the rules of the Nasdaq Stock Market, or Nasdaq, to receive such grants. Because the number of shares available for issuance under the Original 2021 Plan has been (and the number of shares available under the Amended and Restated 2021 Plan, if approved, will be) carefully calibrated to enable us to make equity grants to our current employees and non-employee directors, we expect to continue using Inducement Awards for our new hire equity grants for the foreseeable future.

Rationale for Amendment to the Evergreen Provision

We operate in a competitive market and equity grants are essential in helping us attract, motivate and retain talented individuals. Our compensation committee and the board of directors believe our equity-based compensation programs enable us to maintain our competitive position regarding recruiting and retaining highly skilled and engaged personnel. We also believe that equity grants are a key element of our compensation program.

The current evergreen provision calculation is based solely on shares of common stock that are issued and outstanding. In order for us to continue to leverage equity grants consistently with our historic practice as part of our strategy to attract, motivate and retain employees and non-employee directors, we propose to include the shares of common stock underlying our outstanding prefunded warrants in calculating the total number of shares of common stock that are issued and outstanding for purposes of calculating the annual evergreen increase. The Amended and Restated 2021 Plan would only affect future annual increases to our share reserve starting on January 1, 2027.

The issuance of prefunded warrants has provided significant benefits to our investors and to us. Investors often prefer to limit their ownership of a public company’s voting securities to certain thresholds (ranging from 4.99% to 19.99%), as exceeding such limits could cause undesirable accounting and reporting obligations for the investor. By purchasing prefunded warrants, our investors defer owning the underlying common stock until such time as the investor elects to exercise the prefunded warrant. Prefunded warrants therefore allow our investors to make larger investments than they otherwise might be willing or able to make. Importantly, prefunded warrants are also beneficial to us, because they are issued at substantially the same offering price as shares of our common stock, and the cash proceeds are received by us immediately upon issuance of the prefunded warrant. Prefunded warrants therefore allow us to raise more capital from investors who have concerns over undesirable accounting or reporting obligations than if we were to issue only common stock.

Accordingly, we have issued prefunded warrants on multiple occasions during the past several years. In connection with private placements and follow-on public offerings, we issued and sold prefunded warrants and warrants to purchase shares of common stock (which can be exercised by the holder for prefunded warrants in lieu of common stock), as described further below:

As of April 15, 2026, an aggregate of 13,107,620 prefunded warrants to purchase shares of common stock remain outstanding and are exercisable at any time at an exercise price of $0.0014 per share (subject to the applicable beneficial ownership limitation for each holder) and an aggregate of 8,206,109 warrants to purchase shares of common stock (which can be exercised by the holder for prefunded warrants in lieu of common stock) remain outstanding.

Upon the closing of each of those offerings, the investors who purchased the prefunded warrants effectively paid the per share offering price of our common stock less a fractional $0.0014 per share for each prefunded warrant. By issuing prefunded warrants at substantially the same offering price as our common stock, we increased the proceeds received by us from the applicable offering, which provided the funds needed to progress our research and develop our product candidates. However, despite the company receiving the financial benefit of the cash proceeds from issuance of prefunded warrants, these offerings also resulted in significant dilution to the equity holdings of our executives, employees and directors, such that our key talent no longer holds market-competitive interests in the company. The evergreen provision in the Original 2021 Plan does not reflect this dilution, because the number of outstanding shares of our common stock did not increase as a result of the prefunded warrant issuances, and therefore the number of outstanding shares of common stock that is used to calculate the annual increases under the evergreen provision in the Original 2021 Plan did not increase proportionally. We are seeking to remedy this to maintain a proportional annual increase in our equity-based compensation program, which we rely on to attract and retain talented individuals.

As of April 15, 2026, we had an aggregate of 5,982,839 shares of common stock outstanding and an aggregate of prefunded warrants to purchase 13,107,620 shares of common stock outstanding. If these were the numbers of outstanding shares of common stock and prefunded warrants on January 1, 2027, under the evergreen provision in the Original 2021 Plan, an additional 299,141 shares would be added to the share reserve (assuming the full 5% evergreen is applied). Under the same scenario, if the Amended and Restated 2021 Plan is approved by stockholders, an additional 954,522 shares would be added to the share reserve (assuming the full 5% evergreen is applied), which reflects an increase of 655,381 shares over the evergreen provision in the Original 2021 Plan. If stockholders approve the Amended and Restated 2021 Plan, the change to the evergreen calculation would start in 2027 and continue through 2031 (the year in which the plan expires) but would not retroactively affect the annual increases that previously occurred under the Original 2021 Plan.

We believe that the approval of the Amended and Restated 2021 Plan to amend the evergreen provision is consistent with the spirit of the evergreen provision in the Original 2021 Plan, namely to annually increase the share reserve under the plan on a percent-of-company basis, consistent with our peers and other companies that we compete with for talent. Our board of directors and compensation committee, with the guidance of its independent compensation consultant, Aon’s Human Capital Solutions practice, a division of Aon plc, or Aon (formerly known as Radford), have determined that the inclusion of prefunded warrants in calculating the total number of shares of common stock that are issued and outstanding on each January 1 for purposes of calculating the annual increase is reasonable based on our modeling and will not result in excessive dilution to our stockholders. In addition, including the prefunded warrants would allow us to have a number of shares reserved under our Amended and Restated 2021 Plan that is comparable in size to similarly situated companies that do not have prefunded warrants outstanding.

We anticipate that if the Amended and Restated 2021 Plan is approved by our stockholders, the number of shares reserved under the Amended and Restated 2021 Plan, as increased annually pursuant to the evergreen provision, will be sufficient to provide equity incentives to attract, retain, and motivate employees for at least the next several years. If our stockholders do not approve the Amended and Restated 2021 Plan, our plans to operate our business may be materially impacted because we may not have sufficient shares available under the Original 2021 Plan to attract and retain new

employees or to motivate and retain our existing employees in the future. This could require us to offer a different mix of equity and cash-based incentives, including increasing our annual cash incentive bonuses rather than relying heavily on equity awards to compete for talent. We believe that the alternatives to our current compensation program would not have significant long-term retention value and would not serve to align our employees’ interests as closely with those of our stockholders in the absence of equity incentives. As we scale our growth to progress our research and product candidates, we want to continue a culture of ownership that aligns directly with our mission and values.

The following table sets forth information, as of April 15, 2026, regarding all of our outstanding equity awards under all of our equity-based compensation plans and arrangements under which shares of common stock may be issued. This includes shares subject to outstanding equity awards under our 2020 Plan, the Original 2021 Plan, the 2022 Inducement Plan and the Xilio Therapeutics, Inc. 2025 Equity Incentive Plan, or the 2025 Plan (which was adopted and approved by stockholders in November 2025 and was specifically designed to provide equity incentives to employees that are tied to the warrants issued in connection with our June 2025 follow-on offering); 356,869 shares available for grant under the Original 2021 Plan as of such date; 49,555 shares available for grant under the 2022 Inducement Plan as of such date; and 21,805 shares available for grant under the 2025 Plan as of such date; but does not include shares issuable under our 2021 Employee Stock Purchase Plan, or the 2021 ESPP.

As of April 15, 2026, there were no outstanding stock appreciation rights, or SARs, nor other stock-based awards outstanding under any of the 2020 Plan, the Original 2021 Plan, the 2022 Inducement Plan or the 2025 Plan.

We believe that our equity compensation programs have been integral to our success in the past and will be important to our ability to succeed in the future. If the Amended and Restated 2021 Plan is not approved by our stockholders, we will not be able to make equity incentive awards to meet our retention needs in a highly competitive market, which could have an adverse impact on our business. Further, if the Amended and Restated 2021 Plan is not approved, we could be forced to increase cash compensation, which will reduce the resources we are able to allocate to meeting our business needs and objectives. Therefore, the approval of the Amended and Restated 2021 Plan is vital to our future success.

Our board of directors believes approval of the Amended and Restated 2021 Plan is in the best interests of the company and its stockholders and recommends a vote “FOR” the approval of the Amended and Restated 2021 Plan.

Following below is a discussion of:

Summary of Material Features of the Amended and Restated 2021 Plan

The material features of the Amended and Restated 2021 Plan are:

Information Regarding Overhang and Burn Rate

In developing the amendment to the evergreen provision in the Amended and Restated 2021 Plan and analyzing the impact of utilizing equity as a means of compensation on our stockholders, our management and board of directors considered both our “overhang” and our “burn rate.”

Overhang is a measure of potential dilution, which we define as the sum of (i) the total number of shares underlying all equity awards outstanding and (ii) the total number of shares available for future grants, divided by the number of shares of common stock outstanding. As of April 15, 2026, there were 2,786,451 shares underlying all equity awards outstanding, 428,229 shares available for future awards under our equity incentive plans and 5,982,839 shares of common stock outstanding. Accordingly, our overhang was 16.8% as of April 15, 2026 if the 13,107,620 prefunded warrants were treated as outstanding common stock for purposes of the overhang calculation. Assuming the Amended and Restated 2021 Plan is approved, the 2027 annual evergreen increase would be 954,522 shares if the same number of shares of common stock and same number of prefunded warrants remain outstanding on January 1, 2027. In such case, our overhang on January 1, 2027 would be 21.8% if the outstanding prefunded warrants were treated as outstanding common stock for purposes of the calculation.

Burn rate provides a measure of the potential dilutive impact of our equity award program, which we calculate by dividing the number of shares subject to equity awards granted during the year (including inducement grants) by the basic weighted average number of shares outstanding. Set forth below is a table that reflects our burn rate for the 2025, 2024 and 2023 calendar years, excluding the one-time grants made under the 2025 Plan in 2025, as well as an average over those years.

Equity Compensation Plan Information

For more information on our equity compensation plans, please see the section titled “Securities Authorized for Issuance Under Equity Compensation Plans—Equity Compensation Plan Information” contained elsewhere in this proxy statement.

If this proposal is approved by our stockholders, we intend to register the shares subject to the evergreen increase in 2027 and future years under the Amended and Restated 2021 Plan by filing a Registration Statement on Form S-8 as soon as practicable following such annual increases.

Summary of the Amended and Restated 2021 Plan

The following description of certain features of the Amended and Restated 2021 Plan is intended to be a summary only. The full text of the Amended and Restated 2021 Plan is attached hereto as Appendix A.

Shares Available for Issuance. The Amended and Restated 2021 Plan provides that the maximum number of shares that can be granted subject to awards under the plan is equal to the sum of (1) 875,208 (which number is the sum of the initial reserve under the Original 2021 Plan and each annual evergreen increase from January 1, 2022 to January 1, 2026); plus (2) such additional number of shares of common stock (up to 283,359 shares) as is equal to the sum of (x) the number of shares of common stock that were reserved for issuance under the 2020 Plan that were available for grant under the 2020 Plan as of the initial effective date and (y) the number of shares of common stock subject to awards, whether granted under the 2020 Plan or outside of the 2020 Plan prior to the initial effective date, which awards expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the company at their original issuance price pursuant to a contractual repurchase right and that, prior to the initial effective date, would have become available for issuance under the 2020 Plan (subject, however, in the case of incentive stock options, to any limitations of the Code); plus (3) an annual increase to be added on the first day of each fiscal year, commencing on January 1, 2027 and continuing for each fiscal year until, and including, January 1, 2031, equal to the lesser of (i) 5% of the sum of (a) the number of outstanding shares of common stock on such date and (b) the number of shares of common stock subject to prefunded warrants issued by the company and outstanding as of such date, and (ii) the number of shares of common stock determined by the board of directors. The maximum number of shares of common stock that can be issued under the Amended and Restated 2021 Plan as incentive stock options is 379,261.

The Amended and Restated 2021 Plan provides that the maximum aggregate amount of cash and value of awards (calculated based on grant date fair value for financial reporting purposes) granted to any individual non-employee director in any calendar year may not exceed $1,000,000; provided, however, that fees paid by the company on behalf of any non-employee director in connection with regulatory compliance and any amounts paid to a non-employee director as reimbursement of an expense will not count against this limit. Exceptions to this limitation may only be made by our board of directors in extraordinary circumstances provided that any non-employee director receiving additional compensation does not participate in the decision to award such compensation. This limitation does not apply to cash or awards granted to a non-employee director in his or her capacity as an advisor or consultant to the company.

For purposes of counting the number of shares available for the grant of awards under the Amended and Restated 2021 Plan, all shares of common stock covered by SARs shall be counted against the number of shares available for the grant of awards under the Amended and Restated 2021 Plan. However, SARs that may be settled only in cash will not be so counted. Similarly, to the extent that a restricted stock unit award may be settled only in cash, no shares will be counted against the shares available for the grant of awards under the Amended and Restated 2021 Plan. In addition, if we grant a SAR in tandem with a stock option for the same number of shares of our common stock and provide that only one such award may be exercised, referred to as a tandem SAR, only the shares covered by the stock option, and not the shares covered by the tandem SAR, will be so counted, and the expiration of one in connection with the other’s exercise will not restore shares to the Amended and Restated 2021 Plan.

Shares covered by awards under the Amended and Restated 2021 Plan that expire or are terminated, surrendered, or cancelled without having been fully exercised or are forfeited in whole or in part (including as the result of shares subject to such award being repurchased by us at the original issuance price pursuant to a contractual repurchase right) or that result in any shares not being issued (including as a result of an award being settled in cash rather than stock) will again be available for the grant of awards under the Amended and Restated 2021 Plan (subject, in the case of incentive stock options, to any limitations under the Code). In the case of the exercise of a SAR, the number of shares counted against the shares available for the grant of awards under the Amended and Restated 2021 Plan will be the full number of shares subject to the SAR multiplied by the percentage of the SAR actually exercised, regardless of the number of shares actually used to settle the SAR upon exercise, and the shares covered by a tandem SAR will not again become available for grant upon the expiration or termination of the tandem SAR.

Shares of common stock that are delivered (by actual delivery, attestation, or net exercise) to us by a participant to purchase shares of common stock upon exercise of an award or to satisfy tax withholding obligations (including shares retained from the award creating the tax obligation) will be added back to the number of shares available for the future grant of awards under the Amended and Restated 2021 Plan.

In connection with a merger or consolidation of an entity with us or our acquisition of property or stock of an entity, our board of directors may grant awards under the Amended and Restated 2021 Plan in substitution for any stock options or other stock or stock-based awards granted by such entity or an affiliate thereof on such terms as our board of directors determines appropriate in the circumstances, notwithstanding any limitation on awards contained in the Amended and Restated 2021 Plan. No such substitute awards shall count against the overall share limit contained in the Amended and Restated 2021 Plan, except as required by reason of Section 422 and related provisions of the Code.

Types of Awards. The Amended and Restated 2021 Plan provides for the following types of awards:

Descriptions of Awards

Stock Options. A participant who is awarded a stock option receives the right to purchase a specified number of shares of common stock at a specified exercise price and subject to the other terms and conditions that are specified in connection with the award agreement. A stock option that is not intended to be an “incentive stock option” is a “nonstatutory stock option.” Stock options may not be granted at an exercise price that is less than 100% of the fair market value of our common stock on the date of grant. If our board of directors approves the grant of a stock option with an exercise price to be determined on a future date, the exercise price may not be less than 100% of the fair market value of our common stock on that future date. Under present law, incentive stock options may not be granted at an exercise price less than 110% of the fair market value in the case of stock options granted to participants who hold more than 10% of the total combined voting power of all classes of our stock or any of our subsidiaries. Under the terms of the Amended and Restated 2021 Plan, stock options may not be granted for a term in excess of ten years (and, under present law, five years in the case of incentive stock options granted to participants who hold greater than 10% of the total combined voting power of all classes of our stock or any of our subsidiaries).

The Amended and Restated 2021 Plan permits participants to pay the exercise price of stock options using one or more of the following manners of payment: (i) payment by cash or by check, (ii) except as may otherwise be provided in the applicable award agreement or approved by our board of directors, in connection with a “cashless exercise” through a broker, (iii) to the extent provided in the applicable award agreement or approved by our board of directors, and subject to certain conditions, by delivery to us (either by actual delivery or attestation) of shares of common stock owned by the participant valued at their fair market value, (iv) to the extent provided in an applicable nonstatutory stock option award agreement or approved by our board of directors, by delivery of a notice of “net exercise” as a result of which we will retain a number of shares of common stock otherwise issuable pursuant to the stock option equal to the aggregate exercise price for the portion of the stock option being exercised divided by the fair market value of our common stock on the date of exercise, (v) to the extent permitted by applicable law and provided for in the applicable award agreement or approved by our board of directors, by any other lawful means, or (vi) to the extent provided for in the applicable award agreement or approved by our board of directors, by any combination of these forms of payment. No stock option granted under the Amended and Restated 2021 Plan may contain a provision entitling the participant to the automatic grant of additional stock options in connection with any exercise of the original stock option. No stock options granted under the Amended and Restated 2021 Plan may provide for the payment or accrual of dividend equivalents.

SARs. A participant who is awarded a SAR receives, upon exercise, a number of shares of our common stock, or cash (or a combination of shares of our common stock and cash) determined by reference to appreciation, from and after the date of grant, in the fair market value of a share of our common stock over the measurement price. The Amended and Restated 2021 Plan provides that the measurement price of a SAR may not be less than 100% of the fair market value of our common stock on the date the SAR is granted (provided, however, that if our board of directors approves the grant of a SAR effective as of a future date, the measurement price shall not be less than 100% of the fair market value on such future date) and that SARs may not be granted with a term in excess of 10 years. No SARs granted under the Amended and Restated 2021 Plan may contain a provision entitling the participant to the automatic grant of additional SARs in connection with any exercise of the original SAR. No SARs granted under the Amended and Restated 2021 Plan may provide for the payment or accrual of dividend equivalents.

Limitation on Repricing of Stock Options or SARs. Unless such action is approved by our stockholders or otherwise permitted under the terms of the Amended and Restated 2021 Plan in connection with certain changes in capitalization and reorganization events, we may not (i) amend any outstanding stock option or SAR granted under the Amended and Restated 2021 Plan to provide an exercise price or measurement price per share that is lower than the then-current exercise price or measurement price per share of such outstanding stock option or SAR, (ii) cancel any outstanding stock option or SAR (whether or not granted under the Amended and Restated 2021 Plan) and grant in substitution therefor new awards under the Amended and Restated 2021 Plan (other than certain substitute awards issued in connection with a merger or consolidation of an entity with us or an acquisition by us, described above) covering the same or a different number of shares of our common stock and having an exercise price or measurement price per share lower than the then-current exercise price or measurement price per share of the cancelled stock option or SAR, (iii) cancel in exchange for a cash payment any outstanding stock option or SAR with an exercise price or measurement price per share above the then-current fair market value of our common stock, or (iv) take any other action under the Amended and Restated 2021 Plan that constitutes a “repricing” within the meaning of the rules of the Nasdaq Stock Market or any other exchange or marketplace on which the company’s common stock is listed or traded.

Restricted Stock Awards. A participant who is granted a restricted stock award is entitled to acquire shares of our common stock, subject to our right to repurchase all or part of such shares at their issue price or other stated or formula price (or to require forfeiture of such shares if issued at no cost), in the event that the conditions specified in the applicable award are not satisfied prior to the end of the applicable restriction period established for such award. Any dividends (whether paid in cash, stock or property) declared and paid by us with respect to shares of restricted stock will be paid to the participant only if and when such shares become free from the restrictions on transferability and forfeitability that apply to such shares. No interest will be paid on unvested dividends.

Restricted Stock Unit Awards. A participant who is granted a restricted stock unit award is entitled to receive shares of our common stock, or cash equal to the fair market value of such shares or a combination thereof, in the event that the conditions specified in the applicable award are satisfied, with such shares to be delivered at the time such award vests or on a deferred basis pursuant to the terms and conditions established by our board of directors. Our board of directors may provide that settlement of restricted stock units will be deferred, on a mandatory basis or at the election of the participant, in a manner that complies with Section 409A of the Code. A participant has no voting rights with respect to any restricted stock unit award. A restricted stock unit award agreement may provide the applicable participant with the right to receive an amount equal to any dividends or other distributions declared and paid on an equal number of outstanding shares of our common stock. Any such dividend equivalents may be settled in cash and/or shares of our common stock and will be subject to the same restrictions on transfer and forfeitability as the restricted stock units with respect to which such dividend equivalents are awarded. No interest will be paid on dividend equivalents.

Other Stock-Based Awards. Under the Amended and Restated 2021 Plan, our board of directors may grant other awards of shares of our common stock, and other awards that are valued in whole or in part by reference to, or are otherwise based on, shares of our common stock or other property, having such terms and conditions as our board of directors may determine. We refer to these types of awards as other stock-based awards. Other stock-based awards may be available as a form of payment in settlement of other awards granted under the Amended and Restated 2021 Plan or as

payment in lieu of compensation to which a participant is otherwise entitled. Other stock-based awards may be paid in shares of our common stock or in cash, as our board of directors may determine. The award agreements for other stock-based awards may provide the participant who receives such award with the right to receive dividend equivalents. Dividend equivalents may be settled in cash and/or shares of our common stock and will be subject to the same restrictions on transfer and forfeitability as the other stock-based award with respect to which they are awarded. No interest will be paid on dividend equivalents.

Eligibility to Receive Awards

All of our employees, officers, and directors, as well as our consultants and advisors, are eligible to receive awards under the Amended and Restated 2021 Plan. However, incentive stock options may only be granted to our employees, employees of our present or future parent or subsidiary corporations as defined in Sections 424(e) or (f) of the Code, and employees of any other entities the employees of which are eligible to receive incentive stock options under the Code.

As of April 15, 2026, approximately 106 persons were eligible to receive awards under the Amended and Restated 2021 Plan, including 83 employees (including four executive officers who are current employees), eight non-employee directors, seven consultants and eight advisors (excluding consultants).

On April 27, 2026, the last reported sale price of our common stock on the Nasdaq Stock Market was $8.18.

Transferability of Awards

Awards may not be sold, assigned, transferred, pledged or otherwise encumbered by a participant, either voluntarily or by operation of law, except by will or the laws of descent and distribution or, other than in the case of an incentive stock option, pursuant to a qualified domestic relations order. During the life of the participant, awards are exercisable only by the participant. However, except with respect to awards that are subject to Section 409A of the Code and incentive stock options, our board of directors may permit or provide in an award for the gratuitous transfer of the award by the participant to or for the benefit of any immediate family member, family trust or other entity established for the benefit of the participant and/or an immediate family member thereof if we would be eligible to use a Form S-8 under the Securities Act of 1933, as amended, for the registration of the sale of the common stock subject to such award to the proposed transferee. Further, we are not required to recognize any such permitted transfer until such time as the permitted transferee has, as a condition to the transfer, delivered to us a written instrument in form and substance satisfactory to us confirming that such transferee will be bound by all of the terms and conditions of the award. None of the restrictions described in this paragraph prohibit a transfer from the participant to the company.

No Rights as a Stockholder

No participant or designated beneficiary shall have any rights as a stockholder with respect to any shares of common stock to be distributed with respect to an award granted under the Amended and Restated 2021 Plan until becoming a record holder of such shares, subject to the terms of an award agreement.

Clawback

In accepting an award under the Amended and Restated 2021 Plan, a participant agrees to be bound by any clawback policy that the company has in effect or may adopt in the future, including without limitation the company’s Executive Compensation Clawback Policy. A participant further agrees to promptly take any action necessary to effectuate any forfeiture or reimbursement that may be required by such clawback policy.

Awards Granted under the Original 2021 Plan

The following table sets forth information about equity-based awards granted under the Original 2021 Plan since adoption of the Original 2021 Plan through April 15, 2026, to the individuals and groups described in the below table.

New Plan Benefits Table

The granting of awards under the Amended and Restated 2021 Plan is discretionary, and we cannot now determine the number or type of awards to be granted in the future to any particular person or group, other than as set forth below. We are obligated, pursuant to the terms of our Amended and Restated Director Compensation Policy, to grant each of our non-employee directors (i) upon initial election to the board of directors, an initial stock option award to purchase 10,000 shares of common stock and (ii) after serving for at least six months, on the first business day following the date of each annual meeting of stockholders, including the 2026 Annual Meeting, a stock option award to purchase 5,000 shares of common stock.

Administration

The Amended and Restated 2021 Plan will be administered by our board of directors. Our board of directors has the authority to grant awards and to adopt, amend and repeal the administrative rules, guidelines and practices relating to the Amended and Restated 2021 Plan that it deems advisable and to construe and interpret the provisions of the Amended and Restated 2021 Plan and any award agreements entered into under the Amended and Restated 2021 Plan. Our board of directors may correct any defect, supply any omission or reconcile any inconsistency in the Amended and Restated 2021 Plan or any award. All actions and decisions by our board of directors with respect to the Amended and Restated 2021 Plan and any awards made under the Amended and Restated 2021 Plan will be made in our board of directors’ discretion and will be final and binding on all persons having or claiming any interest in the Amended and Restated 2021 Plan or in any award.

Pursuant to the terms of the Amended and Restated 2021 Plan, our board of directors may delegate any or all of its powers under the Amended and Restated 2021 Plan to one or more committees or subcommittees of our board of directors. The board of directors has authorized the compensation committee to administer the Amended and Restated 2021 Plan.

Subject to any requirements of applicable law, the board of directors may delegate to one or more officers the power to grant awards (subject to any limitations under the Amended and Restated 2021 Plan) to employees or officers of the company and to exercise such other powers under the Amended and Restated 2021 Plan as the board of directors may determine, provided that the board of directors shall fix the terms of the awards to be granted by such officers, the maximum number of shares subject to the awards that the officers may grant and the time period in which such awards may be granted; and provided further that no officer shall be authorized to grant awards to any “executive officer” (as defined by Rule 3b-7 under the Securities Exchange Act of 1934, as amended, or the Exchange Act), or to any “officer” (as defined by Rule 16a-1(f) under the Exchange Act).

Subject to applicable limitations contained in the Amended and Restated 2021 Plan, the board of directors, the compensation committee, or any other committee or subcommittee or officer to whom the board of directors has delegated authority pursuant to the Amended and Restated 2021 Plan, as the case may be, selects the recipients of awards and determines (i) the number of shares of common stock, cash or other consideration covered by awards and the terms and conditions of such awards, including the dates upon which such awards become exercisable or otherwise vest, (ii) the exercise or measurement price of awards, if any, and (iii) the duration of awards.

Except as otherwise provided in the Amended and Restated 2021 Plan, each award under the Amended and Restated 2021 Plan may be made alone or in addition or in relation to any other award. The terms of each award need not be identical, and our board of directors need not treat participants uniformly. Our board of directors will determine the effect on an award of the disability, death, termination or other cessation of employment or service, authorized leave of absence or other change in the employment or other service status of a participant, and the extent to which, and the period during which, the participant (or the participant’s legal representative, conservator, guardian or designated beneficiary) may exercise rights or receive any benefits under an award.

The board of directors may at any time provide that any award shall become immediately exercisable in whole or in part, free from some or all restrictions or conditions or otherwise realizable in whole or in part, as the case may be.

In the event of any stock split, reverse stock split, stock dividend, recapitalization, combination of shares, reclassification of shares, spin-off or other similar change in capitalization or event, or any dividend or distribution to holders of our common stock, other than an ordinary cash dividend, we are required to make equitable adjustments (or make substituted awards, as applicable), in the manner determined by our board of directors, to (i) the number and class of securities available under the Amended and Restated 2021 Plan and the number and class of securities that may be issued as

incentive stock options under the Amended and Restated 2021 Plan, (ii) the share counting rules set forth in the Amended and Restated 2021 Plan, (iii) the number, class, exercise, measurement or purchase price and any other per share related provisions of shares subject to each outstanding award, and (iv) any performance goals applicable to an award. In the event we effect a split of our common stock by means of a stock dividend and the exercise price of and the number of shares subject to an outstanding stock option are adjusted as of the date of the distribution of the dividend (rather than as of the record date for such dividend), then a participant who exercises a stock option between the record date and the distribution date for such stock dividend shall be entitled to receive, on the distribution date, the stock dividend with respect to the shares of common stock acquired upon such stock option exercise, notwithstanding the fact that such shares were not outstanding as of the close of business on the record date for such stock dividend.

We will indemnify and hold harmless each director, officer, employee or agent to whom any duty or power relating to the administration or interpretation of the Amended and Restated 2021 Plan has been or will be delegated against any cost or expense (including attorneys’ fees) or liability (including any sum paid in settlement of a claim with our board of directors’ approval) arising out of any act or omission to act concerning the Amended and Restated 2021 Plan unless arising out of such person’s own fraud or bad faith.

Amendment of Awards. Except as otherwise provided under the Amended and Restated 2021 Plan with respect to repricing outstanding stock options or SARs and with respect to actions requiring stockholder approval, our board of directors may amend, modify or terminate any outstanding award, including but not limited to, substituting therefor another award of the same or a different type, changing the date of exercise or realization, and converting an incentive stock option to a nonstatutory stock option, provided that the participant’s consent to any such action will be required unless our board of directors determines that the action, taking into account any related action, does not materially and adversely affect the participant’s rights under the Amended and Restated 2021 Plan or the change is otherwise permitted under the terms of the Amended and Restated 2021 Plan in connection with certain corporate events.

Reorganization Events

The Amended and Restated 2021 Plan contains provisions addressing the consequences of any reorganization event. A reorganization event is defined under the Amended and Restated 2021 Plan as (i) any merger or consolidation of us with or into another entity as a result of which all of our common stock is converted into or exchanged for the right to receive cash, securities or other property, or is cancelled, (ii) any transfer or disposition of all of our common stock for cash, securities or other property pursuant to a share exchange or other transaction or (iii) our liquidation or dissolution.

Provisions Applicable to Awards Other than Restricted Stock. Under the Amended and Restated 2021 Plan, if a reorganization event occurs, our board of directors may take any one or more of the following actions as to all or any (or any portion of) outstanding awards other than restricted stock on such terms as our board of directors determines (except to the extent specifically provided otherwise in an applicable award agreement, another agreement between a participant and us, or another company plan): (i) provide that such awards shall be assumed, or substantially equivalent awards shall be substituted, by the acquiring or succeeding corporation (or an affiliate thereof), (ii) upon written notice to a participant, provide that all unvested awards will be forfeited immediately before the reorganization event and/or that all unexercised awards will terminate immediately prior to the consummation of such reorganization event unless exercised by the participant (to the extent then exercisable) within a specified period following the date of such notice, (iii) provide that outstanding awards shall become exercisable, realizable, or deliverable, or restrictions applicable to an award shall lapse, in whole or in part prior to or upon such reorganization event, (iv) in the event of a reorganization event under the terms of which holders of common stock will receive upon consummation thereof a cash payment for each share surrendered in the reorganization event, or the Acquisition Price, make or provide for a cash payment to participants with respect to each award held by a participant equal to (A) the number of shares of common stock subject to the vested portion of the award (after giving effect to any acceleration of vesting that occurs upon or immediately prior to such reorganization event multiplied by (B) the excess, if any of the Acquisition Price over the exercise, measurement or purchase price of such and any applicable tax withholdings, in exchange for the termination of such award, (v) provide that, in connection with our liquidation or dissolution, awards shall convert into the right to receive liquidation proceeds (if applicable, net of the exercise, measurement or purchase price thereof and any applicable tax withholdings) and (vi) any combination of the foregoing.

Our board of directors is not obligated to treat all awards, all awards held by a participant, or all awards of the same type, identically. Certain restricted stock unit awards that are subject to Section 409A of the Code will be settled in accordance with the terms of the applicable award agreement or as otherwise specified in the Amended and Restated 2021 Plan.

Provisions Applicable to Restricted Stock. Upon the occurrence of a reorganization event other than our liquidation or dissolution, our repurchase and other rights with respect to outstanding restricted stock will inure to the benefit of our successor and will, unless our board of directors determines otherwise, apply to the cash, securities or other property which our common stock was converted into or exchanged for pursuant to such reorganization event in the same manner and to the same extent as they applied to such restricted stock. However, our board of directors may either provide for termination or deemed satisfaction of such repurchase or other rights under the instrument evidencing any restricted stock or any other agreement between a participant and us, either initially or by amendment or provide for forfeiture of such restricted stock if issued at no cost. Upon the occurrence of a reorganization event involving our liquidation or dissolution, except to the extent specifically provided to the contrary in the instrument evidencing any award of restricted stock or any other agreement between the participant and us, all restrictions and conditions on all restricted stock then outstanding shall automatically be deemed terminated or satisfied.

Provisions for Foreign Participants

The board of directors may establish one or more sub-plans under the Amended and Restated 2021 Plan to satisfy applicable securities, tax or other laws of various jurisdictions. The board of directors will establish such sub-plans by adopting supplements to the Amended and Restated 2021 Plan containing any limitations on the board of directors’ discretion under the Amended and Restated 2021 Plan and any additional terms and conditions not otherwise inconsistent with the Amended and Restated 2021 Plan as the board of directors deems necessary or desirable. All supplements adopted by the board of directors will be deemed to be part of the Amended and Restated 2021 Plan, but each supplement will only apply to participants within the affected jurisdiction.

Withholding

The participant must satisfy all applicable federal, state, and local or other income and employment tax withholding obligations before we will deliver stock certificates or otherwise recognize ownership of common stock under an award. We may elect to satisfy the withholding obligations through additional withholding on salary or wages. If we elect not to or cannot withhold from other compensation, the participant must pay us the full amount, if any, required for withholding or have a broker tender to us cash equal to the withholding obligations. Payment of withholding obligations is due before we will issue any shares on exercise, vesting or release from forfeiture of an award or at the same time as payment of the exercise or purchase price, unless we determine otherwise. If provided for in an award or approved by the board of directors, a participant may satisfy the tax obligations in whole or in part by delivery (either by actual delivery or attestation) of shares of common stock, including shares retained from the award creating the tax obligation, valued at their fair market value. However, except as otherwise provided by the board of directors, the total tax withholding where stock is being used to satisfy such tax obligations cannot exceed our minimum statutory withholding obligations (based on minimum statutory withholding rates for federal and state tax purposes, including payroll taxes, that are applicable to such supplemental taxable income), except that, to the extent that we are able to retain shares of common stock having a fair market value that exceeds the statutory minimum applicable withholding tax without financial accounting implications or we are withholding in a jurisdiction that does not have a statutory minimum withholding tax, we may retain such number of shares (up to the number of shares having a fair market value equal to the maximum individual statutory rate of tax) as we shall determine to be necessary to satisfy the tax liability associated with any award. Shares used to satisfy tax withholding requirements cannot be subject to any repurchase, forfeiture, unfulfilled vesting or other similar requirements.

Amendment or Termination

No award may be granted under the Amended and Restated 2021 Plan after October 12, 2031, but awards previously granted may extend beyond that date. Our board of directors may amend, suspend or terminate the Amended and Restated 2021 Plan or any portion of the Amended and Restated 2021 Plan at any time, except that (i) no amendment may be made to the plan to permit a stock option or SAR to be repriced without stockholder approval and (ii) no amendment that would require stockholder approval under the rules of the national securities exchange on which we maintain our primary listing may be made effective unless and until such amendment has been approved by our stockholders. If at any time the approval of our stockholders is required as to any other modification or amendment under Section 422 of the Code or any successor provision with respect to incentive stock options, our board of directors may not effect such modification or amendment without such approval.

Unless otherwise specified in the amendment, any amendment to the Amended and Restated 2021 Plan adopted in accordance with the procedures described above will apply to, and be binding on the holders of, all awards outstanding under the Amended and Restated 2021 Plan at the time the amendment is adopted, provided that our board of directors determines that such amendment, taking into account any related action, does not materially and adversely affect the rights of participants under the Amended and Restated 2021 Plan. No award will be made that is conditioned on stockholder approval of any amendment to the Amended and Restated 2021 Plan unless the award provides that (i) it will terminate or be forfeited if stockholder approval of such amendment is not obtained within no more than 12 months from the date the award was granted and (ii) it may not be exercised or settled (or otherwise result in the issuance of shares of our common stock) prior to the receipt of such stockholder approval.

If stockholders do not approve the Amended and Restated 2021 Plan, the Amended and Restated 2021 Plan will not go into effect; however, the Original 2021 Plan will remain in effect and we will continue to grant awards under that plan subject to its existing terms. In this event, the board of directors will consider whether to adopt alternative arrangements based on its assessment of our needs.

Federal Income Tax Consequences

The following is a summary of the United States federal income tax consequences that generally will arise with respect to awards granted under the Amended and Restated 2021 Plan. This summary is based on the federal tax laws in effect as of the date of this proxy statement. In addition, this summary assumes that all awards are exempt from, or comply with, the rules under Section 409A of the Code regarding nonqualified deferred compensation. Changes to these laws could alter the tax consequences described below.

Incentive Stock Options. A participant will not have income upon the grant of an incentive stock option. Also, except as described below, a participant will not have income upon exercise of an incentive stock option if the participant has been employed by the company or its corporate parent or 50% or majority-owned corporate subsidiary at all times beginning with the stock option grant date and ending three months before the date the participant exercises the stock option. If the participant has not been so employed during that time, then the participant will be taxed as described below under “Nonstatutory Stock Options.” The exercise of an incentive stock option may subject the participant to the alternative minimum tax.

A participant will have income upon the sale of the stock acquired under an incentive stock option at a profit (if sales proceeds exceed the exercise price). The type of income will depend on when the participant sells the stock. If a participant sells the stock more than two years after the stock option was granted and more than one year after the stock option was exercised, then all of the profit will be long-term capital gain. If a participant sells the stock prior to satisfying these waiting periods, then the participant will have engaged in a disqualifying disposition and a portion of the profit will be ordinary income and a portion may be capital gain. This capital gain will be long-term if the participant has held the stock for more than one year and otherwise will be short-term. If a participant sells the stock at a loss (sales proceeds are less than the exercise price), then the loss will be a capital loss. This capital loss will be long-term if the participant held the stock for more than one year and otherwise will be short-term.

Nonstatutory Stock Options. A participant will not have income upon the grant of a nonstatutory stock option. A participant will have compensation income upon the exercise of a nonstatutory stock option equal to the value of the stock on the day the participant exercised the stock option less the exercise price. Upon sale of the stock, the participant will have capital gain or loss equal to the difference between the sales proceeds and the value of the stock on the day the stock option was exercised. This capital gain or loss will be long-term if the participant has held the stock for more than one year and otherwise will be short-term.

Stock Appreciation Rights. A participant will not have income upon the grant of a SAR. A participant generally will recognize compensation income upon the exercise of a SAR equal to the amount of the cash and the fair market value of any stock received. Upon the sale of the stock, the

participant will have capital gain or loss equal to the difference between the sales proceeds and the value of the stock on the day the SAR was exercised. This capital gain or loss will be long-term if the participant held the stock for more than one year and otherwise will be short-term.

Restricted Stock Awards. A participant will not have income upon the grant of restricted stock unless an election under Section 83(b) of the Code is made within 30 days of the date of grant. If a timely 83(b) election is made, then a participant will have compensation income equal to the value of the stock less the purchase price, if any. When the stock is sold, the participant will have capital gain or loss equal to the difference between the sales proceeds and the value of the stock on the date of grant. If the participant does not make an 83(b) election, then when the stock vests the participant will have compensation income equal to the value of the stock on the vesting date less the purchase price, if any. When the stock is sold, the participant will have capital gain or loss equal to the sales proceeds less the value of the stock on the vesting date. Any capital gain or loss will be long-term if the participant held the stock for more than one year and otherwise will be short-term.

Restricted Stock Units. A participant will not have income upon the grant of a restricted stock unit award. A participant is not permitted to make a Section 83(b) election with respect to a restricted stock unit award. When the shares of common stock are delivered with respect to the restricted stock units (which may be upon vesting or may be at a later date), the participant will have income on the date of delivery in an amount equal to the fair market value of the stock on such date less the purchase price, if any. When the stock is sold, the participant will have capital gain or loss equal to the sales proceeds less the value of the stock on the delivery date. Any capital gain or loss will be long-term if the participant held the stock for more than one year and otherwise will be short-term.

Other Stock-Based Awards. The tax consequences associated with any other stock-based award will vary depending on the specific terms of such award. Among the relevant factors are whether or not the award has a readily ascertainable fair market value, whether or not the award is subject to forfeiture provisions or restrictions on transfer, the nature of the property to be received by the participant under the award, and the participant’s holding period and tax basis for the award or underlying common stock.

Tax Consequences to the Company. There will be no tax consequences to the company except that the company will be entitled to a deduction when a participant has compensation income, subject to the limitations of Section 162(m) of the Code.

Interests of Certain Persons in this Proposal

Our executive officers and members of our board of directors have an interest in this proposal by virtue of their being eligible to receive equity awards under the Amended and Restated 2021 Plan.

It is not possible to determine the benefits that will be received by participants in the Amended and Restated 2021 Plan, including our named executive officers and our non-employee directors, in the future because all grants are made in the discretion of our board of directors or our compensation committee. Neither our board of directors nor our compensation committee has approved any awards that are conditioned upon stockholder approval of the Amended and Restated 2021 Plan.

Other than as described herein, we do not believe that our executive officers or directors have substantial interests in this proposal that are different from or greater than those of any other of our stockholders.

OUR board of directors recommends voting “FOR” THE APPROVAL OF OUR AMENDED AND RESTATED 2021 STOCK INCENTIVE PLAN.

CORPORATE GOVERNANCE

Director Nomination Process

Our nominating and corporate governance committee of the board of directors is responsible for identifying and evaluating individuals qualified to serve as directors, consistent with criteria approved by our board of directors, and recommending the persons to be nominated for election as directors, except where we are legally required by contract, law or otherwise to provide third parties with the right to nominate director candidates. Our nominating and corporate governance committee establishes the process for identifying and evaluating director candidates, which generally includes initially seeking recommendations from our board of directors and members of management. Dr. Bello, who was first elected as a director in June 2025, and Dr. Blanchard, who was first elected as a director on April 15, 2026, were initially introduced to the nominating and corporate governance committee by another member of our board of directors. The nominating and corporate governance committee reviews the qualifications, experience, and background of candidates and selects the candidates. The committee may elect to use a third-party search firm in situations where particular qualifications or expertise are required or where existing contacts are not sufficient to identify an appropriate candidate. Final candidates are interviewed by the members of the nominating and corporate governance committee, and all members of the board of directors are also given the opportunity to meet with the candidate and provide their feedback. After review and deliberation of all feedback and data, the nominating and corporate governance committee makes its recommendation to our board of directors.

Board Member Selection Criteria

Our board of directors aspires to have a board that, taken as a whole, embodies a broad spectrum of skills, experiences and backgrounds. Accordingly, the board of directors strives to attract potential nominees with different skills, experiences and backgrounds in the candidate pool from which the nominating and corporate governance committee recommends candidates. Our nominating and corporate governance committee’s and our board of directors’ priority in selecting board members is identification of persons who will further the interests of our stockholders. In addition, our board of directors periodically reviews our corporate governance practices, including our classified board structure and supermajority voting provisions in light of our stage of development, stockholder feedback, and evolving governance practices.

In considering whether to recommend to our board of directors any particular candidate for inclusion in our board of directors’ slate of recommended director nominees, including candidates recommended by stockholders, the nominating and corporate governance committee applies the criteria set forth in our corporate governance guidelines. These criteria include the candidate’s reputation for integrity, honesty, and adherence to high ethical standards, demonstrated business acumen and experience, ability to exercise sound judgment in matters that relate to our current and long-term objectives, willingness to participate in meetings and contribute positively to our decision-making process, commitment to understanding our company and our industry, and the ability to understand the sometimes conflicting interests of our stakeholders and to act in the interests of all of our stockholders. In addition, nominees should not have, nor appear to have, a conflict of interest that would impair the nominee’s ability to represent the interests of all stockholders and to fulfill the responsibilities of a director.

The director biographies included in this proxy statement indicate each nominee’s experience, qualifications, attributes and skills that led our nominating and corporate governance committee and our board of directors to conclude such individual should continue to serve as a director. Our nominating and corporate governance committee and our board of directors believe that each of the nominees has the individual attributes and characteristics required of each of our directors, and the nominees as a group possess the skill sets and specific experience desired of our board of directors as a whole.

Stockholder Nominations

Stockholders may recommend individuals to the nominating and corporate governance committee for consideration as potential director candidates. Any such proposals must be submitted to our corporate secretary at our principal executive offices in accordance with the procedures and deadlines referenced below under the heading “Stockholder Proposals for our 2027 annual meeting.” For such recommendation to be considered, the nominating stockholder must comply with the procedural requirements and provide the specific information required by our bylaws, which includes, without limitation, appropriate biographical information and background materials to allow the nominating and corporate governance committee to properly evaluate the potential director candidate, information with respect to the stockholder or group of stockholders proposing the candidate, including the number of shares of common stock owned by such stockholder or group of stockholders, as well as other information required by our bylaws or SEC regulations.

Assuming that the required information has been provided on a timely basis, any recommendations received from stockholders will be evaluated in the same manner as potential nominees proposed by the nominating and corporate governance committee. If our board of directors decides to nominate a stockholder-recommended candidate and recommends his or her election, then his or her name will be included on our proxy card for the next annual meeting.

Director Independence

Under the listing rules of Nasdaq, independent directors must comprise a majority of a listed company’s board of directors within one year of listing. In addition, the Nasdaq listing rules require that, subject to specified exceptions, each member of a listed company’s audit, compensation, and nominating and corporate governance committees be independent under the Securities Exchange Act of 1934, as amended, or the Exchange Act. Under applicable Nasdaq rules, a director will only qualify as an “independent director” if, in the opinion of the listed company’s board of directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director.

Audit committee members must also satisfy the independence criteria set forth in Rule 10A-3 under the Exchange Act. In order to be considered independent for purposes of Rule 10A-3, a member of an audit committee of a listed company may not, other than in his or her capacity as a member of the audit committee, the board of directors or any other board committee, accept, directly or indirectly, any consulting, advisory or other compensatory fee from the listed company or any of its subsidiaries or otherwise be an affiliated person of the listed company or any of its subsidiaries.

In addition, compensation committee members must also satisfy the independence criteria set forth in Rule 10C-1 under the Exchange Act. In affirmatively determining the independence of any director who will serve on a company’s compensation committee, Rule 10C-1 under the Exchange Act requires that the board of directors must consider, for each member of a compensation committee, all factors specifically relevant to determining whether a director has a relationship to such company which is material to that director’s ability to be independent from management in connection with the duties of a compensation committee member, including, but not limited to: (1) the source of compensation of the director, including any consulting, advisory or other compensatory fee paid by such company to the director; and (2) whether the director is affiliated with the company or any of its subsidiaries or affiliates.

In March 2026, our board of directors undertook a review of the composition of our board of directors and its committees and the independence of each director. Based upon information requested from and provided by each director concerning his or her background, employment and affiliations, including family relationships, our board of directors has determined that each of our directors serving on the board of directors at that time, with the exception of Dr. Russo, is an “independent director” as defined under applicable Nasdaq rules, including, in the case of all the members of our audit committee, the independence criteria set forth in Rule 10A-3 under the Exchange Act, and in the case of all the members of our compensation committee, the independence criteria set forth in Rule 10C-1 under the Exchange Act. In April 2026, (i) in connection with her initial appointment, our board of directors determined that Dr. Blanchard is an “independent director” as defined under applicable Nasdaq rules, including the independence criteria set forth in Rules 10A-3 and 10C-1 under the Exchange Act, and (ii) in connection with her appointment to the compensation committee, our board of directors determined that Dr. Brennan is an “independent director” as defined under applicable Nasdaq rules, including the independence criteria set forth in Rule 10C-1 under the Exchange Act. In making such determinations, our board of directors considered the relationships that each such non-employee director has with our company and all other facts and circumstances that our board of directors deemed relevant in determining his or her independence, including the beneficial ownership of our capital stock by each non-employee director. Dr. Russo is not an independent director under these rules because she is our president and chief executive officer.

Board Committees

Our board of directors has established an audit committee, a compensation committee, a nominating and corporate governance committee and a research and development committee. Each of these committees operates under a written charter. A current copy of each committee’s charter is posted on the “Corporate Governance” section of the “Investors & Media” section of our website, which is located at https://ir.xiliotx.com. Our board of directors also appoints from time-to-time ad hoc committees to address specific matters.

Audit Committee

The current members of our audit committee are James Shannon, M.D., Sara M. Bonstein and Cheryl Blanchard, Ph.D. During fiscal 2025, and until Dr. Blanchard’s appointment to the audit committee in April 2026, the members of our audit committee were Ms. Bonstein, Dr. Shannon and Aoife Brennan, M.D. Ms. Bonstein served as chair of the audit committee during fiscal 2025 and until January 2026, and Dr. Shannon has served as the chair of the audit committee since January 2026. Our audit committee met six times during 2025. Our audit committee’s responsibilities include:

All audit and non-audit services, other than de minimis non-audit services, to be provided to us by our independent registered public accounting firm must be approved in advance by our audit committee.

Our board of directors has determined that Ms. Bonstein is an “audit committee financial expert” as defined in applicable SEC rules. We believe that the composition of our audit committee meets the requirements for independence under current Nasdaq and SEC rules and regulations. Our board of directors has also determined that each member of our audit committee can read and understand fundamental financial statements, in accordance with applicable Nasdaq requirements. In arriving at these determinations, the board of directors has examined each audit committee member’s scope of experience and the nature of their employment in the corporate finance sector. The audit committee may form and delegate authority to one or more subcommittees as it deems appropriate from time to time under the circumstances.

Compensation Committee

The current members of our compensation committee are Cheryl Blanchard, Ph.D., Aoife Brennan, M.D. and Robert Ross, M.D. During fiscal 2025, the members of our compensation committee were Christina Rossi, Dr. Ross and Paul Clancy. Mr. Clancy resigned from our board of directors in January 2026, and the members of our compensation committee were Ms. Rossi and Dr. Ross until Dr. Blanchard’s appointment to the committee and Ms. Rossi’s resignation from our board of directors in April 2026. Dr. Blanchard began serving as chair of the compensation committee in April 2026, succeeding Ms. Rossi who served as the chair of the compensation committee until April 2026. Our compensation committee met five times during 2025. Our compensation committee’s responsibilities include:

We believe that the composition of our compensation committee meets the requirements for independence under current Nasdaq and SEC rules and regulations. The compensation committee may form and delegate authority to one or more subcommittees as it deems appropriate from time to time under the circumstances (including (a) a subcommittee consisting of a single member and (b) a subcommittee consisting of at least two members, each of whom qualifies as a “non-employee director,” as such term is defined from time to time in Rule 16b-3 promulgated under the Exchange Act and the rules and regulations thereunder). As part of determining the performance and compensation of our named executive officers and directors, our compensation committee receives recommendations from our chief executive officer (except with respect to her own performance and compensation). Our chief executive officer’s performance and compensation is approved by our board of directors based upon the recommendation of our compensation committee. No member of the management team, including our chief executive officer, has a role in determining his or her own compensation.

The compensation committee has the authority, in its sole discretion, to retain or obtain, at our expense, the advice of compensation consultants, legal counsel or other advisors to assist the compensation committee in performing its responsibilities. In 2025, the compensation committee used the services of Aon’s Human Capital Solutions practice, a division of Aon plc, or Aon (formerly known as Radford) to provide analysis and recommendations to the compensation committee regarding cash and equity compensation for our executive officers and directors. Aon was retained exclusively by the compensation committee and has not been retained by management to perform any work for the company other than projects performed at the direction of the compensation committee. Aon reports to the compensation committee and not to management, although it meets with management for purposes of gathering information for its analyses and recommendations. Representatives of Aon attend regular meetings of the compensation committee, including executive sessions from time to time without any members of management present. The compensation committee has assessed the independence of Aon pursuant to SEC and Nasdaq rules and concluded that no conflict of interest exists that would prevent Aon from independently representing the compensation committee.

Nominating and Corporate Governance Committee

The current members of our nominating and corporate governance committee are Akintunde Bello, Ph.D., Daniel Curran, M.D. and Yuan Xu, Ph.D. Dr. Curran serves as chair of the nominating and corporate governance committee. Our nominating and corporate governance committee met three times during 2025. Our nominating and corporate governance committee’s responsibilities include:

We believe that the composition of our nominating and corporate governance committee meets the requirements for independence under current Nasdaq and SEC rules and regulations. The nominating and corporate governance committee may form and delegate authority to one or more subcommittees as it deems appropriate from time to time under the circumstances.

Research and Development Committee

The current members of our research and development committee are Akintunde Bello, Ph.D., Aoife Brennan, M.D., Daniel Curran, M.D., Robert Ross, M.D., James Shannon, M.D. and Yuan Xu, Ph.D. Dr. Ross serves as chair of the research and development committee. Our research and development committee was formed on December 9, 2025 and did not meet during 2025. Our research and development committee's responsibilities include:

Board of Director Meetings and Attendance

Our board of directors recognizes the importance of director attendance at board and committee meetings. The full board of directors met seven times during 2025. During 2025, each member of the board of directors attended in person or participated in 75% or more of the aggregate of (i) the total number of meetings held by the board of directors (during the period that such person served as a director) and (ii) the total number of meetings held by all committees of the board of directors on which such person served (during the periods that such person served).

Director Attendance at Annual Meeting of Stockholders

Our corporate governance guidelines provide that directors are responsible for attending the annual meeting of stockholders. For our annual meeting of stockholders in 2025, eight of the ten directors serving on the board at such time were in attendance.

Code of Business Conduct and Ethics and Corporate Governance Guidelines

We have adopted a written code of business conduct and ethics that applies to our directors, officers and employees, including our principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. We have posted a current copy of the code on the “Corporate Governance” section of the “Investors & Media” section of our website, which is located at https://ir.xiliotx.com. In addition, we intend to post on our website all disclosures that are required by law or Nasdaq listing standards concerning any amendments to, or waivers from, any provision of the code of business conduct and ethics.

Our board of directors has also adopted corporate governance guidelines to assist the board of directors in the exercise of its duties and responsibilities and to serve the best interests of our company and our stockholders. A copy of the corporate governance guidelines is available on the “Corporate Governance” section of the “Investors & Media” section of our website, which is located at https://ir.xiliotx.com.

Insider Trading Policy

We have adopted an insider trading policy governing the purchase, sale and/or other dispositions of company securities by our directors, officers, employees and other covered persons. We believe the insider trading policy is reasonably designed to promote compliance with insider trading laws, rules and regulations, and Nasdaq listing standards. A copy of our insider trading policy is filed as Exhibit 19 to our Annual Report on Form 10-K for the fiscal year ended December 31, 2025.

Policies and Practices Related to the Grant of Certain Equity Awards

Board Leadership Structure

Our corporate governance guidelines provide that the nominating and corporate governance committee shall periodically assess the board of directors’ leadership structure, including whether the offices of chief executive officer and chair of the board of directors should be separate. Our guidelines provide the board of directors with flexibility to determine whether the two roles should be combined or separated based upon our needs and the board of directors’ assessment of its leadership from time to time. We do not currently have a lead independent director because the chair of our board of directors is independent within the meaning of the Nasdaq listing rules.

We currently separate the roles of chief executive officer and chair of the board of directors, and our nominating and corporate governance committee and board of directors believe it is appropriate for our chief executive officer to serve as a member of our board of directors. Our chief executive officer is responsible for setting the strategic direction for our company and the day-to-day leadership and performance of our company, while the chair of our board of directors presides over meetings of the board of directors, including executive sessions of the board of directors, and performs oversight responsibilities. Separating the duties of the chair from the duties of the chief executive officer allows our chief executive officer to focus on our day-to-day business, while allowing the chair to lead the board of directors in its fundamental role of providing advice to and independent oversight of management. Specifically, our chair runs meetings of our independent directors, facilitates communications between management and the board of directors, and assists with other corporate governance matters. Our board of directors believes that this structure ensures a greater role for the independent directors in the oversight of our company and active participation of the independent directors in setting agendas and establishing priorities and procedures for the work of our board of directors. Our board of directors believes its administration of its risk oversight function has not affected its leadership structure. Our board of directors has concluded that the current leadership structure described above is appropriate for us at this time, however, the nominating and corporate governance committee will continue to periodically review our leadership structure and may recommend such changes in the future as it deems appropriate.

Role of the Board in Risk Oversight

One of the key functions of our board of directors is informed oversight of our risk management processes. Our board of directors does not have a standing risk management committee, but rather administers this oversight function directly through the board of directors as a whole, as well as through various standing committees of our board of directors that address risks inherent in their respective areas of oversight. In particular, our board of directors is responsible for monitoring and assessing strategic risk exposure, including reviewing our policies and practices with respect to risk assessment and risk management, and regularly discusses with management our significant risk exposures, the potential impact of these risks on our business and the steps we take to manage them. Additionally, our audit committee has the responsibility to consider and discuss our major financial risk exposures and the steps our management has taken to monitor and control these exposures, including discussing guidelines and policies to govern the process by which risk assessment and risk management is undertaken, including the process by which we manage our exposure to cybersecurity risks, as well as directors’ and officers’ liability insurance. The audit committee discusses these matters with members of management on a periodic basis, and the audit committee is notified between such updates regarding significant new risks, including with respect to cybersecurity threats or incidents. The audit committee also monitors compliance with legal and regulatory requirements.

Communication with Our Directors

Any interested party with concerns about our company may report such concerns to the board of directors, or the chair of our board of directors, or otherwise the chair of the nominating and corporate governance committee, by submitting a written communication to the attention of such director at the following address:

Xilio Therapeutics, Inc.

828 Winter Street, Suite 300

Waltham, Massachusetts 02451

Attention: Corporate Secretary

You may submit your concern anonymously or confidentially by postal mail. You may also indicate whether you are a stockholder, customer, supplier, or other interested party.

A copy of any such written communication may also be forwarded to our legal counsel and a copy of such communication may be retained for a reasonable period of time. The director may discuss the matter with our legal counsel, with independent advisors, with non-management directors, or with our management, or may take other action or no action as the director determines in good faith, using reasonable judgment and discretion.

Communications may be forwarded to all directors if they relate to important substantive matters and include suggestions or comments that may 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.

The audit committee oversees the procedures for the receipt, retention, and treatment of complaints received by us regarding accounting, internal accounting controls, or audit matters, and the confidential, anonymous submission by employees of concerns regarding questionable accounting, internal accounting controls or auditing matters. Concerns regarding questionable accounting or auditing matters or complaints regarding accounting, internal accounting controls or auditing matters may be submitted in writing to our chief operating officer and the chair of our audit committee at 828 Winter Street, Suite 300, Waltham, MA 02451 or via the toll-free telephone number 866-454-2061.

EXECUTIVE OFFICERS

Set forth below is certain information, as of April 15, 2026, regarding our executive officers.

René Russo, Pharm.D.'s biography is on page 8 of this proxy statement.

Christopher Frankenfield has served as our chief financial officer since August 2024 and our chief operating officer since August 2023. Mr. Frankenfield previously served as our chief legal and administrative officer from August 2022 to August 2023 and as our general counsel from March 2021 to August 2022. Prior to joining us, Mr. Frankenfield served in roles of increasing responsibility at Blueprint Medicines Corporation, or Blueprint, from August 2015 to March 2021, including as vice president of corporate legal affairs from July 2019 to March 2021. While at Blueprint, Mr. Frankenfield was responsible for a range of corporate legal activities, including public company reporting, capital markets strategy and follow-on equity offerings, collaborations and partnerships, and supporting commercial product launches. Prior to joining Blueprint, Mr. Frankenfield was a senior associate at Wilmer Cutler Pickering Hale and Dorr LLP, where his practice focused on capital markets and strategic transactions, public company reporting and corporate governance matters. Mr. Frankenfield began his career in the advisory practice at PricewaterhouseCoopers LLP. He received his B.A. in economics from the College of William & Mary and his J.D. from the University of Virginia School of Law.

Katarina Luptakova, M.D. has served as our chief medical officer since September 2023. Dr. Luptakova previously served as our senior vice president, medical, from October 2022 to September 2023 and as our vice president, clinical research, from December 2021 to October 2022. Dr. Luptakova is a hematologist and oncologist with 20 years of experience in clinical practice and oncology drug development. Prior to joining us, Dr. Luptakova served as vice president, clinical development at Constellation Pharmaceuticals, Inc., a biopharmaceutical company, from April 2020 to October 2021, through its acquisition by MorphoSys AG in July 2021. Prior to that, Dr. Luptakova served as senior medical director and clinical lead at Tesaro, Inc., or Tesaro, a pharmaceutical company, from March 2018 to April 2020, and as medical director from September 2017 to March 2018. While at Tesaro, Dr. Luptakova contributed to the successful development and commercialization of multiple cancer therapies, including Zejula® (niraparib) and Blenrep® (belantamab mafodotin-blmf). Prior to Tesaro, Dr. Luptakova held roles of increasing responsibility in medical affairs at Takeda Oncology, the global oncology business unit of Takeda Pharmaceutical Company Limited. Earlier in her career, Dr. Luptakova was an attending physician in the Bone Marrow Transplant and Malignant Hematology division at Beth Israel Deaconess Medical Center. Dr. Luptakova received an M.D. from the Comenius University School of Medicine, Bratislava, Slovakia and completed her residency training in Internal Medicine at Caritas St. Elizabeth’s Medical Center and a clinical and research fellowship in hematology/oncology at the Beth Israel Deaconess Medical Center in Boston.

Kevin Brennan has served as our senior vice president, finance and accounting, since March 2023. Mr. Brennan has more than 25 years of finance and accounting experience within the biotechnology industry. Prior to joining us, Mr. Brennan most recently served as vice president of finance at Allena Pharmaceuticals, Inc., or Allena, a public biopharmaceutical company, from November 2020 to March 2023, where he oversaw Allena’s accounting and finance operations and strategy, as well as public company reporting. From October 2011 to October 2020, Mr. Brennan held finance and accounting roles of increasing responsibility at Allena. Prior to Allena, Mr. Brennan served in finance and accounting roles at various companies within the biotechnology industry. Mr. Brennan began his career in the audit practice at KPMG LLP, and he received a B.S. in accounting from the Wallace Carroll School of Management at Boston College.

Executive Compensation

The following discussion provides an overview of the compensation for each of René Russo, Pharm.D., our president and chief executive officer, Christopher Frankenfield, our chief financial and operating officer, and Katarina Luptakova, M.D., our chief medical officer, whom we collectively refer to as our named executive officers. This section also provides qualitative information regarding the manner and context in which compensation is awarded to and earned by our executive officers and is intended to place in perspective the data presented in the tables and narrative that follow.

Summary Compensation Table

The following table sets forth information regarding compensation awarded to, earned by or paid to each of our named executive officers for the years ended December 31, 2025 and 2024.

Narrative Disclosure to Summary Compensation Table

Base Salary

We use base salaries to recognize the experience, skills, knowledge and responsibilities required of all our employees, including our named executive officers. None of our named executive officers is currently party to an employment agreement or other agreement or arrangement that provides for automatic or scheduled increases in base salary. However, on an annual basis, our compensation committee reviews and evaluates, with input from our chief executive officer, the need for adjustment, if any, of the base salaries of our named executive officers (other than with respect to herself), and our compensation committee review and evaluates without input from our chief executive officer, the need for adjustment, if any, of the base salary of our chief executive officer, in each case based on, among other things, changes and expected changes in the scope of a named executive officer’s responsibilities, including promotions, the individual contributions made by and performance of the named executive officer during the prior year, our overall growth and development as a company, general salary or other market trends in our industry and among a peer group of companies, and where the named executive officer’s salary falls in the salary range presented by that data.

Effective January 1, 2026, Dr. Russo, Mr. Frankenfield and Dr. Luptakova received annual base salary increases to $666,225, $552,000 and $500,000, respectively.

Annual Bonus

Our board of directors may, in its discretion, award bonuses to our named executive officers from time to time. Our employment agreements with each of our named executive officers provide that they will be eligible for annual performance-based bonuses up to a specified percentage of their salary, subject to approval by our board of directors. For 2025, the target annual bonus, expressed as a percentage of base salary, was 55% for Dr. Russo, 50% for Mr. Frankenfield, and 40% for Dr. Luptakova. We typically establish annual bonus targets based on a set of specified corporate goals for our named executive officers and conduct an annual performance review to determine the attainment of such goals. Our management may propose bonus awards to our compensation committee primarily based on such review process. For each of 2024 and 2025, our chief executive officer made recommendations to the compensation committee for bonus awards to our named executive officers (other than herself), and our board of directors made the final determination of the eligibility requirements for and the amount and form of such bonus awards based on the recommendation of the compensation committee. The final evaluation made by our board of directors does not involve a predetermined mathematical formula and final bonus amounts may be greater than 100% of the established bonus targets, but may not exceed a maximum of 150% of the established bonus target for each individual.

The categories of corporate goals that we used to propose performance-based bonuses to our compensation committee included: progressing clinical development for our most advanced product candidates; advancing our discovery pipeline for the next generation of transformative tumor-selective therapies and immune cell engagers; and extending our cash runway to enable continued development of our pipeline. In December 2025, based on our achievement or partial achievement of specific goals within each category, as well as additional achievements that were not reflected in the approved corporate goals, and key challenges that were outside of the company’s control in 2025, our board of directors determined that the company achieved 105% of the corporate goals. Based upon these corporate achievements, and considering subjective factors related to individual performance, the compensation committee approved the following 2025 annual cash bonus payments for each of our named executive officers:

In addition to the annual performance-based bonus program described above, the board of directors approved one-time discretionary bonuses of $128,740 for Dr. Russo and $106,620 for Mr. Frankenfield in recognition of their extraordinary efforts in negotiating and executing our collaboration, license and option agreement with AbbVie Group Holdings Limited, or AbbVie, and the related stock purchase agreement with AbbVie Inc., which agreements we refer to as the AbbVie collaboration. Our board of directors viewed the transaction as strategically significant because it provided external validation of our platform, established a collaboration with a major biopharmaceutical company, and generated substantial upfront cash proceeds for our company. These bonuses were outside our regular annual incentive program and are not intended to be a recurring element of compensation.

For 2026, the target annual bonus percentage is 60% for Dr. Russo, 50% for Mr. Frankenfield and 40% for Dr. Luptakova.

Equity Incentives

Although we do not have a formal policy with respect to the grant of equity incentive awards to our executive officers, or any formal equity ownership guidelines applicable to them, we believe that equity grants provide our executives with a strong link to our long-term performance, create an ownership culture and help to align the interests of our executives and our stockholders and our compensation committee reviews executive equity holdings and retention levels as part of its annual compensation review. In addition, we believe that equity grants with a time-based vesting feature promote executive retention because this feature provides an incentive for our executive officers to remain in our employment during the vesting period. Accordingly, our board of directors periodically reviews the equity incentive compensation of our executive officers, including our named executive officers, and from time to time may grant equity incentive awards to them in the form of stock options or restricted stock units.

Prior to our initial public offering in October 2021, our executive officers were eligible to participate in our 2020 Plan. Following our initial public offering in October 2021, our employees and executive officers became eligible to receive stock options and other equity awards pursuant to our 2021 Plan and our 2025 Plan, approved by our stockholders in November 2025.

Awards of stock options, restricted stock units and, prior to our initial public offering, restricted stock, to our executive officers have been made by our board of directors or a committee delegated by our board of directors, and these awards have typically been subject to time-based vesting, generally over four years following the vesting commencement date. Upon certain terminations of employment in connection with a change of control, vesting is fully accelerated. During fiscal year 2025, we granted stock options to purchase shares of our common stock to Dr. Russo, Mr. Frankenfield and Dr. Luptakova, as described in more detail in the table below under “-Outstanding Equity Awards at 2025 Fiscal Year End.” These grants included stock options awards granted in January 2025 as annual awards, one-time stock option awards to Dr. Russo and Mr. Frankenfield in April 2025 in recognition of their efforts negotiating and executing the AbbVie collaboration, as well as stock option awards granted in October 2025 in connection with the 2025 Plan. Additionally, on November 21, 2025, our stockholders approved a one-time repricing of certain outstanding employee stock options, pursuant to which the exercise price of stock options representing 157,009 shares held by Dr. Russo, 60,577 shares held by Mr. Frankenfield, and 16,082 shares held by Dr. Luptakova, was reduced to $21.00 per share. If a repriced stock option is exercised prior to the 12-month anniversary of the repricing date, then the original exercise price applicable to the stock option, rather than the new exercise price, must be paid by the option holder, except in the case of the death or disability of the option holder or a change in control of the company. In light of the 2025 Plan stock option awards and the stock option repricing, both of which were effected in November 2025, our board of directors and compensation committee determined that employees who received stock options under the 2025 Plan would not be eligible for an annual equity award in 2026. As a result, no annual equity awards were made to Dr. Russo, Mr. Frankenfield or Dr. Luptakova in 2026.

Outstanding Equity Awards at 2025 Fiscal Year End

The following table sets forth information regarding all outstanding stock options and shares of restricted stock held by each of our named executive officers as of December 31, 2025.