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:

EQUILLIUM, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

PRELIMINARY COPY - SUBJECT TO COMPLETION

EQUILLIUM, INC.

2223 Avenida De La Playa, Suite 105

La Jolla, CA 92037

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

Virtual Meeting Only – No Physical Meeting Location

To Be Held On May 28, 2026

Dear Stockholder:

You are cordially invited to attend the 2026 annual meeting of stockholders (the “Annual Meeting”) of Equillium, Inc., a Delaware corporation (the “Company”). The meeting will be held on Thursday, May 28, 2026, starting at 1:00 p.m. (Pacific Time). The Annual Meeting will be a virtual meeting of stockholders, which will be conducted only via a live audio webcast. You will be able to attend the Annual Meeting, submit your questions and vote online during the meeting by visiting www.proxydocs.com/EQ. A complete list of record stockholders will be available for examination on a reasonably accessible electronic network by any stockholder for any purpose germane to the Annual Meeting for a period of ten days ending on the day before the Annual Meeting date. If you would like to view the list, please email us at [email protected]. The meeting will be held for the following purposes:

These items of business are more fully described in the Proxy Statement accompanying this Notice.

The Annual Meeting will be held virtually through a live webcast. Stockholders of record at the close of business on April 1, 2026 and their proxy holders will be able to attend the Annual Meeting, submit questions and vote during the live webcast by visiting www.proxydocs.com/EQ and entering the Control Number included in your Notice of Internet Availability or in the instructions that you received via email. Please refer to the additional logistical details

and recommendations in the accompanying proxy statement. You may log in beginning at 12:45p.m. Pacific Time, on May 28, 2026.

Only stockholders of record at the close of business on April 1, 2026 and their proxy holders may vote at the meeting or any adjournment thereof.

Your vote is important. Voting your shares will ensure the presence of a quorum at the Annual Meeting and will save us the expense of further solicitation.

Important Notice Regarding the Availability of Proxy Materials for

the Annual Meeting to Be Held on May 28, 2026 starting at 1:00 p.m. (Pacific Time) at

www.proxydocs.com/EQ.

The proxy statement and annual report to stockholders are available at www.proxydocs.com/EQ.

Please promptly vote your shares by following the instructions for voting on the Notice Regarding the Availability of Proxy Materials or, if you received a paper or electronic copy of our proxy materials, by completing, signing, dating and returning your proxy card or by Internet or telephone voting as described on your proxy card.

You are cordially invited to attend the Annual Meeting online. Whether or not you expect to attend the Annual Meeting, please vote over the telephone or the internet as instructed in these materials, or, if you receive a paper proxy card by mail, by completing and returning the proxy mailed to you, as promptly as possible in order to ensure your representation at the Annual Meeting. Even if you have voted by proxy, you may still vote online if you attend the Annual Meeting.

EQUILLIUM, INC.

2223 Avenida De La Playa, Suite 105

La Jolla, CA 92037

PROXY STATEMENT

FOR THE 2026 ANNUAL MEETING OF STOCKHOLDERS

Virtual Meeting Only – No Physical Meeting Location

To Be Held On May 28, 2026

This proxy statement (the “Proxy Statement”) and our annual report for the fiscal year ended December 31, 2025 (the “Annual Report” and, together with this Proxy Statement, the “proxy materials”) are being furnished by and on behalf of the board of directors (the “Board” or “Board of Directors”) of Equillium, Inc. (the “Company,” “Equillium,” “we,” “us,” or “our”), in connection with our 2026 annual meeting of stockholders (the “Annual Meeting”). The Notice of Annual Meeting and this Proxy Statement are first being distributed or made available, as the case may be, on or about , 2026.

TABLE OF CONTENTS

QUESTIONS AND ANSWERS ABOUT THESE PROXY MATERIALS AND VOTING

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

Pursuant to rules adopted by the Securities and Exchange Commission (the “SEC”), we have elected to provide access to our proxy materials over the internet. Accordingly, we have sent you a Notice of Internet Availability of Proxy Materials (the “Notice”) because the Board of the Company is soliciting your proxy to vote at the 2026 Annual Meeting of Stockholders, including at any adjournments or postponements of the meeting. All stockholders will have the ability to access the proxy materials on the website referred to in the Notice or request to receive a printed set of the proxy materials. Instructions on how to access the proxy materials over the internet or to request a printed copy may be found in the Notice.

We intend to first mail the Notice and make this Proxy Statement and the form of proxy available to stockholders on or about , 2026.

Will I receive any other proxy materials by mail?

We may send you a proxy card, along with a second Notice, on or after , 2026.

How do I attend the Annual Meeting?

This year’s Annual Meeting will be a virtual meeting, which will be conducted entirely online via webcast to allow greater participation. You may attend, vote and ask questions at the Annual Meeting by following the instructions provided on the Notice or proxy card to log in to www.proxydocs.com/EQ. If you are a stockholder of record, you will be asked to provide the control number from your Notice or proxy card. If you are a beneficial owner of shares registered in the name of your broker, bank or other agent, follow the instructions from your broker or bank.

The webcast of the Annual Meeting will begin promptly at 1:00 p.m. Pacific Time. We encourage you to access the meeting prior to the start time. Online check-in will begin at 12:45 p.m. Pacific Time, and you should allow reasonable time for the check-in procedures.

You are entitled to attend the Annual Meeting if you were a stockholder as of the close of business on April 1, 2026, the record date, or hold a valid proxy for the meeting. To be admitted to the Annual Meeting, you will need to visit www.proxydocs.com/EQ and enter the Control Number found next to the label “Control Number” on your Notice or proxy card, or in the email sending you the Proxy Statement. If you are a beneficial stockholder, you should contact the bank, broker or other institution where you hold your account well in advance of the meeting if you have questions about obtaining your control number/proxy to vote.

Whether or not you participate in the Annual Meeting, it is important that you vote your shares.

What if I cannot find my Control Number?

Please note that if you do not have your Control Number and you are a registered stockholder, you will be able to login as a guest. To view the meeting webcast visit www.proxydocs.com/EQ and register as a guest. If you login as a guest, you will not be able to vote your shares or ask questions during the meeting.

If you are a beneficial owner (that is, you hold your shares in an account at a bank, broker or other holder of record), you will need to contact that bank, broker or other holder of record to obtain your Control Number prior to the Annual Meeting.

Where can we get technical assistance if we are having trouble accessing the meeting or during the meeting?

If you have difficulty accessing the meeting or during the meeting, please refer to the technical support telephone number posted on the virtual meeting website login page, where technicians will be available to help you.

For the Annual Meeting, how do we ask questions of management and the Board?

Stockholders may submit questions relevant to the proposals to be voted on at the Annual Meeting for approximately five days in advance of the Annual Meeting through www.proxydocs.com/EQ. We plan to spend up to 15 minutes answering appropriate stockholder questions after the proposals are formally presented and prior to the closing of voting at the Annual Meeting and will include as many stockholder questions that comply with the rules of conduct for the Annual Meeting as the allotted time permits. If we receive substantially similar questions, we will group such questions together and provide a single response to avoid repetition. Questions that are not relevant to the proposals to be voted on at the Annual Meeting and not in compliance with the rules of conduct for the Annual Meeting will not be responded to. Questions may be submitted during the Annual Meeting through www.proxydocs.com/EQ.

Who can vote at the Annual Meeting?

Only stockholders of record at the close of business on April 1, 2026 will be entitled to vote at the Annual Meeting. On this record date, there were shares of common stock outstanding and entitled to vote.

Stockholder of Record: Shares Registered in Your Name

If, on April 1, 2026, your shares were registered directly in your name with our transfer agent, Equiniti Trust Company, LLC, then you are a stockholder of record. As a stockholder of record, you may vote online during the Annual Meeting or vote by proxy. Whether or not you plan to register and attend the Annual Meeting, we urge you to fill out and return your vote by proxy over the telephone, vote by proxy through the internet or voting by proxy using a proxy card that you may request or that we may elect to deliver at a later time to ensure your vote is counted.

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

If on April 1, 2026, your shares were held, not in your name, but rather in an account at a brokerage firm, bank or other similar organization, then you are the beneficial owner of shares held in “street name” and the Notice should be forwarded to you by that organization. The organization holding your account is considered to be the stockholder of record for purposes of voting at the Annual Meeting. As a beneficial owner, you have the right to direct your broker, bank or other agent regarding how to vote the shares in your account. You must follow the instructions provided by your brokerage firm, bank, or other similar organization for your bank, broker or other stockholder of record to vote your shares per your instructions. Alternatively, many brokers and banks provide the means to grant proxies or otherwise instruct them to vote your shares by telephone and via the Internet, including by providing you with a control number via email or on your Notice or your voting instruction form. If your shares are held in an account with a broker, bank or other stockholder of record providing such a service, you may instruct them to vote your shares by telephone (by calling the number provided in the proxy materials) or over the Internet as instructed by your broker, bank or other stockholder of record. If you did not receive a control number via email or on your Notice or voting instruction form, and you wish to vote prior to or at the virtual Annual Meeting, you must follow the instructions from your broker, bank or other stockholder of record, including any requirement to obtain a valid legal proxy. Many brokers, banks and other stockholders of record allow a beneficial owner to obtain a valid legal proxy either online or by mail, and we recommend that you contact your broker, bank or other stockholder of record to do so.

Can I vote my shares by filling out and returning the Notice?

No. The Notice identifies the items to be voted on at the Annual Meeting, but you cannot vote by marking the Notice and returning it. If you would like a paper proxy card, you should follow the instructions in the Notice. The paper proxy card you may receive would also provide instructions as to how to authorize via the Internet or telephone your proxy to vote your shares according to your voting instructions. Alternatively, you can mark the paper proxy card you may receive with how you would like your shares voted, sign and date the proxy card, and return it in the envelope provided.

Will a list of record stockholders as of the record date be available?

For the ten days ending the day prior to the Annual Meeting, a list of our record stockholders as of the close of business on the record date will be available for examination by any stockholder of record for a legally valid purpose at our corporate headquarters during regular business hours. To access the list of record stockholders beginning May 18, 2026 and until the day prior to the Annual Meeting, stockholders should email [email protected].

What am I voting on?

There are four matters scheduled for a vote:

What if another matter is properly brought before the Annual Meeting?

The Board does not know of any other matters to be brought before the Annual Meeting. If other matters are presented, the proxy holders have discretionary authority to vote all proxies in accordance with their best judgment. Discretionary authority for them to do so is provided in the proxy card.

How do I vote?

For Proposal 1, you may either vote “For” all the nominees to the Board or you may “Withhold” your vote for any nominee to the Board that you specify. For each of the other matters to be voted on, you may vote “For” or “Against” or abstain from voting.

The procedures for voting are as follows:

Stockholder of Record: Shares Registered in Your Name

If you are a stockholder of record, you may vote at the Annual Meeting or you may vote by proxy over the telephone, through the internet or using a proxy card that you may request or that we may elect to deliver at a later time. Whether or not you plan to attend the Annual Meeting, we urge you to vote by proxy to ensure your vote is

counted. You may still attend the Annual Meeting and vote at the Annual Meeting even if you have already voted by proxy. This is only required if you want to change your original vote, since votes will not be double counted.

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

If you are a beneficial owner of shares registered in the name of your brokerage firm, bank or other agent, you should have received a voting instruction form with the Notice from that organization rather than from Equillium. Simply complete and mail the voting instruction form to ensure that your vote is counted. Alternatively, you may vote by telephone or over the internet as instructed by your broker, bank or other agent. To vote at the Annual Meeting, you must register at www.proxydocs.com/EQ prior to the deadline of May 27, 2026 at 2:00 p.m. (Pacific Time). You may be instructed to obtain a legal proxy from your broker, bank or other nominee and to submit a copy in advance of the Annual Meeting. Further instruction will be provided to you as part of your registration process.

Internet proxy voting will be provided to allow you to vote your shares online, with procedures designed to ensure the authenticity and correctness of your proxy vote instructions. However, please be aware that you must bear any costs associated with your internet access, such as usage charges from internet access providers and telephone companies.

How many votes do I have?

On each matter to be voted upon, you have one vote for each share of common stock you own as of the close of business on April 1, 2026.

If I am a stockholder of record and I do not vote, or if I return a proxy card or otherwise vote without giving specific voting instructions, what happens?

If you are a stockholder of record and do not vote by completing your proxy card, by telephone, through the internet or online at the Annual Meeting, your shares will not be voted.

If you return a signed and dated proxy card or otherwise vote without marking voting selections, your shares will be voted, as applicable, “For” the election of both nominees for director, “For” the approval of an amendment to our Amended and Restated Certificate of Incorporation to effect a reverse stock split of our common stock at a ratio in the range of 1-for-2 to 1-for-20, inclusive, “For” the ratification of the appointment by the Audit Committee of the Board of Crowe LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026 and

“For” the approval of an increase in authorized shares. If any other matter is properly presented at the meeting, your proxy holder (one of the individuals named on your proxy card) will vote your shares using that individual’s best judgment.

If I am a beneficial owner of shares held in street name and I do not provide my broker or bank with voting instructions, what happens?

If you are a beneficial owner of shares held in street name and you do not instruct your broker, bank or other agent how to vote your shares, your broker, bank or other agent may still be able to vote your shares in its discretion. Brokers, banks and other securities intermediaries may use their discretion to vote your “uninstructed” shares with respect to matters considered to be “routine,” but not with respect to “non-routine” matters. In this regard, Proposal 1 is considered to be “non-routine,” meaning that your broker may not vote your shares on these proposals in the absence of your voting instructions. Proposals 2, 3 and 4 are each considered to be “routine,” meaning that if you do not return voting instructions to your broker by its deadline, your shares may be voted by your broker in its discretion on Proposals 2, 3 and 4.

What are “broker non-votes”?

As discussed above, when a beneficial owner of shares held in street name does not give voting instructions to his or her broker, bank or other securities intermediary holding his or her shares as to how to vote on matters deemed to be “non-routine,” the broker, bank or other such agent cannot vote the shares. When there is at least one “routine” matter that the broker, bank or other securities intermediary votes on, the shares that are un-voted on “non-routine” matters are counted as “broker non-votes.” Proposals 2, 3 and 4 are each considered to be a “routine” matter and we therefore expect brokers, banks or other securities intermediaries to vote on such proposals. Proposal 1 is considered to be “non-routine” and we therefore expect broker non-votes to exist in connection with such proposal.

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

Who is paying for this proxy solicitation?

Equillium will pay for the entire cost of soliciting proxies. In addition to these proxy materials, our directors and employees may also solicit proxies in person, by email, by telephone, or by other means of communication. Directors and employees will not be paid any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks or other agents for the cost of forwarding proxy materials to beneficial owners.

What does it mean if I receive more than one Notice or more than one set of proxy materials?

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

Can I change my vote after submitting my proxy?

Stockholder of Record: Shares Registered in Your Name

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

Your most recent proxy card or telephone or internet proxy is the one that is counted.

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

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

What vote is required for adoption or approval of each proposal and how will votes be counted?

Who will count the vote?

A representative of Equillium will tabulate the votes and act as inspector of elections.

What is the quorum requirement?

A quorum of stockholders is necessary to hold a valid meeting. A quorum will be present if stockholders holding a majority of the outstanding shares entitled to vote are present at the Annual Meeting or represented by proxy. On the record date, there were shares of common stock outstanding and entitled to vote. Thus, the holders of shares must be present or represented by proxy at the Annual Meeting to have a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy (or one is submitted on your behalf by your brokerage firm, bank or other agent) or if you vote at the Annual Meeting. Abstentions and broker non-votes will be counted towards the quorum requirement. If there is no quorum, the holders of a majority of shares present virtually at the Annual Meeting or represented by proxy may adjourn the Annual Meeting to another date.

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

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

What proxy materials are available on the Internet?

The proxy statement and annual report to stockholders are available at www.proxydocs.com/EQ.

Why hold a virtual meeting?

We are excited to continue using the latest technology to provide expanded access, improved communication and cost savings for our stockholders and the Company while providing stockholders the same rights and opportunities to participate as they would have at an in-person meeting. We believe that hosting a virtual meeting is in the best interests of the Company and its stockholders and a virtual meeting enables increased stockholder attendance and participation because stockholders can participate from any location around the world.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Proxy Statement contains certain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, relating to future events. Such statements are only predictions and involve risks and uncertainties, resulting in the possibility that the actual events or performance will differ materially from such predictions. For a nonexclusive list of major factors which could cause the actual results to differ materially from the predicted results in the forward-looking statements, please refer to the “Risk Factors” in Part I. Item 1A of our Annual Report on Form 10-K for the fiscal year ended December 31, 2025 and in our subsequent periodic reports on Form 10-Q and Form 8-K.

PROPOSAL 1: ELECTION OF DIRECTORS

The Board is divided into three classes. Each class consists, as nearly as possible, of one-third of the total number of directors, and each class has a three-year term. Vacancies on the Board may be filled only by persons elected by a majority of the remaining directors. A director elected by the Board to fill a vacancy in a class, including vacancies created by an increase in the number of directors, shall serve for the remainder of the full term of that class and until the director’s successor is duly elected and qualified.

The Board presently has seven members. There are three Class II directors whose term of office expires in 2026: Peter Colabuono, Charles McDermott and Bruce Steel. Proxies may not be voted for a greater number of persons than the number of nominees named in this Proxy Statement. Mr. McDermott and Mr. Steel are each current directors of the Company, were each elected to the Board at the annual meeting of stockholders in 2023 and were each recommended for reelection to the Board by the Nominating and Corporate Governance Committee of the Board. Mr. Colabuono, who is currently serving on the Board, was not nominated for election at the Annual Meeting and his term as a director will end at the Annual Meeting. The Board reduced the size of the Board from seven directors to six directors effective immediately prior to the Annual Meeting. If elected at the Annual Meeting, each of Mr. McDermott and Mr. Steel would serve until the 2029 Annual Meeting of Stockholders and until a successor has been duly elected and qualified, or, if sooner, until the director’s death, resignation or removal. It is the Company’s policy to invite directors and nominees for director to attend the Annual Meeting. Seven of our then-current directors attended our annual meeting of stockholders in 2025.

Directors are elected by a plurality of the votes of the holders of shares present virtually or represented by proxy and entitled to vote on the election of directors. Accordingly, the two nominees receiving the highest number of affirmative votes will be elected. Shares represented by executed proxies will be voted, if authority to do so is not withheld, for the election of Mr. McDermott and Mr. Steel. We have no reason to believe that either nominee will be unavailable or, if elected, will decline to serve. In the event that either nominee should become unavailable for election due to any presently unforeseen reason, proxies will be voted for a substitute as designated by the Board, or alternatively, the Board may leave a vacancy on the Board or reduce the size of the Board.

Nominees for Election to the Board of Directors

The Nominating and Corporate Governance Committee seeks to assemble a Board that, as a whole, possesses the appropriate balance of professional and industry knowledge, financial expertise and high-level management experience necessary to oversee and direct the Company’s business. To that end, the Nominating and Corporate Governance Committee has identified and evaluated the nominees in the broader context of the Board’s overall composition, with the goal of recruiting members who complement and strengthen the skills of other members and who also exhibit integrity, collegiality, sound business judgment and other qualities that the Nominating and Corporate Governance Committee views as critical to effective functioning of the Board. To provide a diverse mix of experience and perspective on the Board, the Nominating and Corporate Governance Committee also takes into account geographic, gender, age, racial and ethnic diversity.

The biographies of each of our nominees for election to the Board as Class II directors, and all other directors are set forth below, including the offices held, other business directorships and the class and term of each director nominee and director. Each of the biographies highlights specific experience, qualifications, attributes, and skills that led us to conclude that such person should serve as a director. We believe that, as a whole, our Board possesses the requisite skills and characteristics, leadership traits, work ethic, and independence to provide effective oversight. No director or executive officer is related by blood, marriage, or adoption to any other director or executive officer. No arrangements or understandings exist between any director and any other person pursuant to which such person was selected as a director or nominee.

Class II Director Nominees for Election at the Annual Meeting

Charles McDermott has served as a member of our Board since September 2018. Mr. McDermott has served on the board of directors and as President and Chief Executive Officer of Primmune Therapeutics, Inc., a privately-held biotechnology company, since March 2019. Mr. McDermott has served as a Managing Member of McDermott Consulting, LLC since September 2018. From September 2017 to May 2018, Mr. McDermott served as President and Chief Business Officer of Impact Biomedicines, Inc., a privately-held biotechnology company. Prior to that, Mr. McDermott served as President and Chief Business Officer of Kala Pharmaceuticals, Inc., a publicly-held biopharmaceutical company, from June 2015 to August 2017. Mr. McDermott currently serves as chairman of the board of directors of Anavo Therapeutics GmbH, a privately-held biotechnology company. Mr. McDermott holds an M.B.A. from the University of San Diego, an M.A. in Molecular, Cellular and Developmental Biology from the University of California at Santa Barbara, a B.S. in Biochemistry and Molecular Biology from the University of California Santa Cruz and a Certificate in Clinical Trial Design and Management from the University of California San Diego Extension.

Skills and Qualifications

Our Nominating and Corporate Governance Committee and Board believe that Mr. McDermott is qualified to serve on our Board due to his biopharmaceutical and executive experience.

Mr. Steel has served as our Chief Executive Officer since January 2020 and as a member of our board of directors since March 2017. He served as our President and Chief Executive Officer from December 2019 through September 2025. He served as our President and Chief Business Officer from June 2018 through December 2019. Mr. Steel is a co-founder of Equillium. Mr. Steel is the founder and has served as the Managing Director of BioMed Ventures, an investment firm owned by BioMed Realty, LP, since 2010. From 2008 to 2010, Mr. Steel served as the Chief Business Officer at Anaphore, Inc., a privately-held pharmaceutical company. Mr. Steel received his B.A. degree from Dartmouth College and M.B.A. degree from the Marshall School of Business at the University of Southern California, and he holds the designation of Chartered Financial Analyst.

Skills and Qualifications

Our Nominating and Corporate Governance Committee and Board believe that Mr. Steel is qualified to serve on our Board due to his experience in founding, managing and building companies and investment experience.

THE BOARD OF DIRECTORS RECOMMENDS

A VOTE “FOR” EACH NAMED NOMINEE.

Class III Directors Continuing in Office Until the 2027 Annual Meeting of Stockholders

Mr. Bradbury has served as the Chairman of the Board since September 2025 and has been a member of our Board since March 2017. He served as our Executive Chairman of the Board from January 2020 to September 2025. He served as our Chief Executive Officer from June 2018 through December 2019. Mr. Bradbury is a co-founder of Equillium and served as our President from March 2017 until June 2018. Mr. Bradbury is the founder and has served as the managing member of BioBrit, LLC (“BioBrit”), a life science consulting and investment firm, since September

2012. Mr. Bradbury served as President, Chief Executive Officer and a director of Amylin Pharmaceuticals, Inc., a publicly-held biopharmaceutical company, from March 2007 until Amylin’s acquisition by Bristol-Myers Squibb Company in August 2012. Mr. Bradbury has served on the board of directors of Castle Biosciences, Inc since July 2019, where he also serves on the compensation committee and as chairman of the board. He has served on the board of directors of Biocon Biologics Ltd. since January 2019, where he also serves on the audit committee. He has served on the board of directors of Vivani Medical, Inc. since March 2024, where he also serves on the audit committee.

Additionally, Mr. Bradbury serves on the boards of many private companies. Mr. Bradbury previously served on the boards of directors of Intercept Pharmaceuticals, Inc., a publicly-held biotechnology company, from 2016 to 2023; Biocon Ltd., a publicly-held biopharmaceutical company, from 2013 to 2022; Corcept Therapeutics Incorporated, a publicly-held biotechnology company, from 2012 to 2019; Geron Corporation, a publicly-held biotechnology company, from 2012 to 2019; Illumina, Inc., a publicly-held biotechnology company, from 2004 to 2017; and Panacea Acquisition Corporation, a publicly-held special purpose acquisition company, from 2020 to 2021. Mr. Bradbury holds a Bachelor of Pharmacy from Nottingham University and a Diploma in Management Studies from the University of West London in the United Kingdom.

Skills and Qualifications

Our Nominating and Corporate Governance Committee and Board believe that Mr. Bradbury’s experience as our former Chief Executive Officer and his other executive and board experience, qualifies him to serve as a member of our Board.

Martha J. Demski has served as a member of our Board since September 2018. In August 2023 she joined the board of directors and as chair of the audit committee and a member of the compensation committee of Alpha Teknova Inc., a publicly-held biotechnology company. She previously served on the board of directors and as lead director and member of the audit committee of Chimerix, Inc. from March 2005 to April 2025. She also previously served as chair of the audit committee and member of the compensation committee of ADMA Biologics, Inc. from June 2020 to June 2023, Adamas Pharmaceuticals, Inc. from March 2014 to November 2021, and Neothetics, Inc. from July 2014 to January 2018, each a publicly-held biopharmaceutical company. Ms. Demski is a National Association of Corporate Directors Board Governance Fellow. In 2017, she received the Director of the Year in Corporate Governance award by the Corporate Directors Forum. Additionally, Ms. Demski has over 13 years of banking experience with Bank of America. Ms. Demski earned a B.A. from Michigan State University and an M.B.A. from The University of Chicago Booth School of Business with concentrations in accounting and finance.

Skills and Qualifications

Our Nominating and Corporate Governance Committee and Board believe that Ms. Demski is qualified to serve on our Board due to her more than 30 years’ experience in the fields of finance and biotechnology as well as her experience as a member of various boards of directors.

Mark Pruzanski, M.D., has served as a member of our Board since September 2018. Dr. Pruzanski is a physician and entrepreneur with more than 30 years of experience in the life sciences sector. He has served as the Chief Executive Officer Alentis Therapeutics AG since October 2025 and a member of its board of directors since December 2025. Previously, he served as Chief Executive Officer of Versanis Bio, a clinical-stage biotechnology company, from April 2022 to September 2023, where he spearheaded the development of novel therapies for obesity and other cardiometabolic diseases until the company’s acquisition in 2023 by Eli Lilly and Company, and as a member of the board from September 2021 to August 2023. Dr. Pruzanski was also a co-founder and member of the board of directors

of Intercept Pharmaceuticals, Inc., a publicly-held biopharmaceutical company where he served as President and Chief Executive Officer from September 2002 until January 2021. Prior to co-founding Intercept, Dr. Pruzanski was a venture partner at Apple Tree Partners, an early-stage life sciences venture capital firm that he co-founded, and an entrepreneur-in-residence at Oak Investment Partners, a venture capital firm. Dr. Pruzanski is a co- author of a number of scientific publications and is named as an inventor on several patents. Additionally, Dr. Pruzanski currently serves on the boards of multiple private companies, the Emerging Companies Section of the Biotechnology Innovation Organization (BIO), a biotechnology-focused trade association, and the Foundation for Defense of Democracies, a non-profit policy institute focusing on foreign policy and national security. Dr. Pruzanski received his M.D. from McMaster University in Hamilton, Canada, a M.A. degree in International Affairs from the Johns Hopkins University School of Advanced International Studies in Bologna, Italy and Washington, D.C., and a bachelor’s degree from McGill University in Montreal, Canada.

Skills and Qualifications

Our Nominating and Corporate Governance Committee and Board believe that Dr. Pruzanski is qualified to serve on our Board due to his experience in founding, managing and building life sciences companies as well as his venture capital experience.

Class I Directors Continuing in Office Until the 2028 Annual Meeting of Stockholders

Barbara Troupin, M.D., has served as a member of our Board since February 2022. Dr. Troupin has worked as a fractional Chief Medical Officer for Laguna Biotherapeutics Inc. since May 2023, and previously as a strategic advisor and advisory board member for Atacana, Inc. from January 2024 until December 2025, a strategic advisor for Terns Pharmaceuticals, Inc. from October 2024 until March 2025, and as a senior clinical advisor and advisory board member for Ilant Health, Inc. from May 2023 until December 2024. She also has been a member of the board of directors at ProSciento, a private equity-backed privately-held clinical research organization, since January 2025. Dr. Troupin was the Senior Vice President, Medical Affairs at MyoKardia, Inc., a publicly-held biopharmaceutical company, from April 2020 until March 2021, where she was responsible for launch preparation in the United States and European Union through the time of MyoKardia’s acquisition by and integration into Bristol Myers Squibb. Prior to joining MyoKardia, Dr. Troupin was the Chief Medical Officer of ERX Pharmaceuticals, a privately-held pharmaceutical company, from December 2018 until December 2019. Prior to that, Dr. Troupin held positions with Aquinox Pharmaceuticals, Inc., a publicly-held pharmaceutical company, as the Chief Medical Officer, Vice President of Clinical Development and Regulatory Affairs between March 2017 and July 2018, and Chief Medical Officer, Vice President of Clinical Development between October 2016 and March 2017. Dr. Troupin received her Doctorate in Medicine from the University of Pennsylvania School of Medicine where she also completed her M.B.A. from the Wharton School of Business, with an emphasis in health care management. She holds a B.A. in Biochemistry and Cell Biology from the University of California San Diego.

Skills and Qualifications

Our Nominating and Corporate Governance Committee and Board believe that Dr. Troupin is qualified to serve on our Board due to her extensive experience leading clinical and medical affairs functions.

INFORMATION REGARDING THE BOARD OF DIRECTORS AND CORPORATE GOVERNANCE

Independence of the Board of Directors

As required under The Nasdaq Stock Market (“Nasdaq”) listing standards, a majority of the members of a listed company’s board of directors must qualify as “independent,” as affirmatively determined by the board of directors. Our Board consults with our counsel to ensure that the Board’s determinations are consistent with relevant securities

and other laws and regulations regarding the definition of “independent,” including those set forth in pertinent listing standards of Nasdaq, as in effect from time to time.

Consistent with these considerations, after review of all relevant identified transactions or relationships between each director, or any of such director’s family members, and us, our senior management and our independent auditors, the Board has affirmatively determined that the following four currently serving directors are independent directors as defined by Rule 5605(a)(2) of the Nasdaq Listing Rules: Ms. Demski, Mr. McDermott, Dr. Pruzanski and Dr. Troupin. In addition, the Board affirmatively determined that Dr. Manian, a member of our Board from May 2017 to October 2025, and Dr. Connelly, a member of our Board from March 2017 to October 2025, each were independent during his respective term. In making these determinations, the Board found that none of these directors had a material or other disqualifying relationship with us. Mr. Bradbury and Mr. Steel are not considered independent because of their prior or current employment with us, as applicable, and the Board has preliminarily determined that, in light of Mr. Colabuono’s affiliation with Decheng Capital Management III (Cayman) LLC (with its affiliates and affiliated funds, “Decheng”), a former beneficial owner of more than 5% of our common stock, and our recent acquisition of Ariagen, Inc. (“Ariagen”), which was more than 92% owned by Decheng, Mr. Colabuono was not considered independent.

Board Leadership Structure

Our Board is currently chaired by our Chairman, Mr. Bradbury. On September 30, 2025, Mr. Bradbury transitioned from Executive Chairman of the Board to Chairman of our Board of Directors. In January 2020, Mr. Bradbury transitioned from his prior role of Chief Executive Officer to Executive Chairman of our Board of Directors. With Mr. Bradbury’s extensive history with and knowledge of our company, we believe his role as our Chairman facilitates a regular flow of information between the Board and management and ensures that they both act with a common purpose. Our Board does not have a lead independent director.

Role of the Board in Risk Oversight

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

Meetings of the Board of Directors

The Board met eight times and acted by unanimous written consent four times during 2025. No member of the Board attended fewer than 75% of the aggregate of the total number of meetings of the Board (held during the period for which he or she was a director) and the total number of meetings held by all committees of the Board on which such director served (held during the period that such director served), other than Dr. Pruzanski, who attended more than 75% of the meetings of the Board held during 2025, but fewer than 75% of each of the Nominating and Corporate Governance and Compensation Committee meetings held during 2025, in each case, due to scheduling conflicts.

Executive Sessions

Executive sessions, which are meetings at which only independent directors are present, are regularly scheduled throughout the year, typically at the end of each regular Board meeting and at the end of each committee meeting and as frequently as such independent directors deem appropriate. A director designated at each executive session by the non-management or independent directors, as applicable, presides at the executive sessions.

INFORMATION REGARDING COMMITTEES OF THE BOARD of Directors

The Board has an Audit Committee, a Compensation Committee and a Nominating and Corporate Governance Committee. The following table provides current membership and meeting information for fiscal year 2025 for each of these committees of the Board:

* Committee Chairperson

Below is a description of each committee of the Board.

Each of the committees has authority to engage legal counsel or other experts or consultants, as it deems appropriate to carry out its responsibilities. The Board has determined that each member of each committee meets the applicable Nasdaq rules and regulations regarding “independence” and that each member is free of any relationship that would impair his or her individual exercise of independent judgment with regard to us.

Audit Committee

The Audit Committee of the Board was established by the Board in accordance with Section 3(a)(58)(A) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), to oversee our corporate accounting and financial reporting processes and audits of its financial statements. For this purpose, the Audit Committee performs several functions, including, among other things:

The Audit Committee is composed of three directors: Ms. Demski (chair), Mr. McDermott and Dr. Troupin. The Audit Committee met seven times during the 2025 fiscal year. The Board has adopted a written Audit Committee charter that is available to stockholders on our website at www.equilliumbio.com. The information on our website is not incorporated by reference into this Proxy Statement or our Annual Report on Form 10-K for the fiscal year ended December 31, 2025.

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

The Board has also determined that Ms. Demski qualifies as an “audit committee financial expert,” as defined in applicable SEC rules. The Board made a qualitative assessment of Ms. Demski’s level of knowledge and experience based on a number of factors, including her formal education, prior experience, business acumen and independence.

Compensation Committee

As of October 1, 2025, the Compensation Committee of the Board is composed of two directors: Dr. Pruzanski (chair) and Ms. Demski. Our Board has determined that each of the members of our Compensation Committee is a non-employee director, as defined in Rule 16b-3 promulgated under the Exchange Act and satisfies the Nasdaq independence requirements. The Compensation Committee met three times during the 2025 fiscal year. The Board has adopted a written Compensation Committee charter that is available to stockholders on our website at www.equilliumbio.com. The information on our website is not incorporated by reference into this Proxy Statement or our Annual Report on Form 10-K for the fiscal year ended December 31, 2025.

The Compensation Committee acts on behalf of the Board to review, adopt or recommend to the Board for adoption, and oversee our compensation strategy, policies, plans and programs. For this purpose, the Compensation Committee performs several functions, including, among other things:

Compensation Committee Processes and Procedures

Typically, the Compensation Committee meets at least three times per year (but in no event less than annually) and with greater frequency, if necessary. The agenda for each meeting is usually developed by the chair of the Compensation Committee, in consultation with management. The Compensation Committee meets regularly in executive session. However, from time to time, various members of management and other employees as well as outside advisors or consultants may be invited by the Compensation Committee to make presentations, to provide financial or other background information, advice, recommendations or to otherwise participate in Compensation

Committee meetings. The Chief Executive Officer does not participate in, and is not present during, any deliberations or determinations of the Compensation Committee regarding his compensation or individual performance objectives, which are ultimately determined and approved in executive session. The charter of the Compensation Committee grants the Compensation Committee full access to all books, records, facilities and our personnel. In addition, under its charter, the Compensation Committee has the authority to obtain, at our expense, advice and assistance from internal and external legal, accounting or other advisers and other external resources that the Compensation Committee considers necessary or appropriate in the performance of its duties. The Compensation Committee has direct responsibility for the oversight of the work of any advisers engaged for the purpose of advising the Compensation Committee. In particular, the Compensation Committee has the sole authority to retain compensation consultants to assist in its evaluation of executive and director compensation, including the authority to approve the consultant’s reasonable fees and other retention terms.

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

In November 2024, after taking into account the six factors prescribed by the SEC and Nasdaq referenced above, we re-engaged Radford, an Aon Hewitt Company ("Aon"), as our compensation consultant. As part of its engagement, Aon was requested by the Compensation Committee to re-evaluate the peer group of comparative companies and to undertake a market comparison analysis to assist with evaluating our overall compensation philosophy and approach, salary, bonus and equity compensation for our executives, including our named executive officers, for 2025, as well as compensation guidelines for non-executives. Aon developed an updated peer group recommendation that was presented to the Compensation Committee for its consideration in evaluating and approving salary, bonus and equity compensation decisions for our named executive officers for 2025 and compensation guidelines for non-executives. The publicly-traded peer companies selected and used as part of Aon’s market compensation analysis for 2025 were: aTyr Pharma, Inc., BioAtla, Inc., Bolt Biotherapeutics, Inc., Cardiff Oncology, Inc., Cidara Therapeutics, Inc., Cue Biopharma, Inc., Eledon Pharmaceuticals, Inc., Immunic, Inc., RAPT Therapeutics, Inc., Regulus Therapeutics Inc., Turnstone Biologics Corp., Unity Biotechnology, Inc., Viracta Therapeutics, Inc. and Xilio Therapeutics, Inc.

The Compensation Committee holds one or more meetings at the end of the year and/or during the first quarter of the year to discuss and approve (or make recommendations to the Board for approval, as applicable) annual compensation adjustments, annual bonuses, annual equity awards, and new corporate performance objectives. However, the Compensation Committee also considers matters related to individual compensation, such as compensation for new executive hires and new hire equity grants for executives and non-executives, as well as high-level strategic issues, such as the efficacy of our compensation strategy, potential modifications to that strategy and new trends, plans or approaches to compensation, at various meetings throughout the year. Generally, the Compensation Committee’s process comprises two related elements: the determination of compensation levels and the establishment of performance objectives for the current year. For executives other than the Chief Executive Officer, the Compensation Committee solicits and considers evaluations and recommendations submitted to the Compensation Committee by the Chief Executive Officer. In the case of the Chief Executive Officer, the evaluation of his performance is conducted by the Compensation Committee. For all executives and directors as part of its deliberations, the Compensation Committee may review and consider, as appropriate, materials such as financial reports and projections, operational data, tax and accounting information, tally sheets that set forth the total compensation that may become payable to executives in various hypothetical scenarios, executive and director stock ownership information, company stock performance data, analyses of historical executive compensation levels and current Company-wide compensation levels, compensation data from comparative companies, compensation surveys, and recommendations of any compensation consultant, if applicable.

Nominating and Corporate Governance Committee

The Nominating and Corporate Governance Committee of the Board is responsible for identifying, reviewing and evaluating candidates to serve as our directors (consistent with criteria approved by the Board), reviewing and evaluating incumbent directors, selecting or recommending to the Board for selection candidates for election to the

Board, making recommendations to the Board regarding the membership of the committees of the Board, assessing the performance of the Board, and developing a set of corporate governance principles for us.

The Nominating and Corporate Governance Committee is composed of three directors: Mr. McDermott (chair), Dr. Pruzanski and Dr. Troupin. All of the members of the Nominating and Corporate Governance Committee are independent (as independence is currently defined in Rule 5605(a)(2) of the Nasdaq listing standards). The Nominating and Corporate Governance Committee met three times during the 2025 fiscal year. The Board has adopted a written Nominating and Corporate Governance Committee charter that is available to stockholders on our website at www.equilliumbio.com. The information on our website is not incorporated by reference into this Proxy Statement or our Annual Report on Form 10-K for the fiscal year ended December 31, 2025. The functions of this committee include, among other things:

The Nominating and Corporate Governance Committee believes that candidates for director should have certain minimum qualifications, including the ability to read and understand basic financial statements, being over 21 years of age and having the highest personal integrity and ethics. The Nominating and Corporate Governance Committee also considers such factors as possessing relevant expertise upon which to be able to offer advice and guidance to management, having sufficient time to devote to our affairs, demonstrated excellence in his or her field, having the ability to exercise sound business judgment and having the commitment to rigorously represent the long-term interests of our stockholders. However, the Nominating and Corporate Governance Committee retains the right to modify these qualifications from time to time. Candidates for director nominees are reviewed in the context of the current composition of the Board, our operating requirements and the long-term interests of our stockholders. In conducting this assessment, the Nominating and Corporate Governance Committee typically considers diversity of experience, age, skills and such other factors as it deems appropriate, given the current needs of the Board and us, to maintain a balance of knowledge, experience and capability.

The Nominating and Corporate Governance Committee appreciates the value of thoughtful Board refreshment, and regularly identifies and considers qualities, skills and other director attributes that would enhance the composition of the Board. In the case of incumbent directors whose terms of office are set to expire, the Nominating and Corporate Governance Committee reviews these directors’ overall service to us during their terms, including the number of meetings attended, level of participation, quality of performance and any other relationships and transactions that might impair the directors’ independence. In the case of new director candidates, the Nominating and Corporate Governance Committee also determines whether the nominee is independent for Nasdaq purposes, which

determination is based upon applicable Nasdaq listing standards, applicable SEC rules and regulations and the advice of counsel, if necessary. The Nominating and Corporate Governance Committee then uses its network of contacts to compile a list of potential candidates, but may also engage, if it deems appropriate, a professional search firm. The Nominating and Corporate Governance Committee conducts any appropriate and necessary inquiries into the backgrounds and qualifications of possible candidates after considering the function and needs of the Board. The Nominating and Corporate Governance Committee meets to discuss and consider the candidates’ qualifications and then selects candidates for recommendation to the Board by majority vote.

The Nominating and Corporate Governance Committee will consider director candidates recommended by stockholders. The Nominating and Corporate Governance Committee does not intend to alter the manner in which it evaluates candidates, including the minimum criteria set forth above, based on whether or not the candidate was recommended by a stockholder. Stockholders who wish to recommend individuals for consideration by the Nominating and Corporate Governance Committee to become nominees for election to the Board may do so by delivering a written recommendation to the Nominating and Corporate Governance Committee at the following address: c/o Equillium, Inc., 2223 Avenida de la Playa, Suite 105, La Jolla, California 92037, Attn: Secretary, no later than the close of business on the 90th day nor earlier than the close of business on the 120th day prior to the first anniversary of the preceding year’s annual meeting. Submissions must include the name and address of our stockholder on whose behalf the submission is made; the number of Company shares that are owned beneficially by such stockholder as of the date of the submission; the full name of the proposed candidate; a description of the proposed candidate’s business experience for at least the previous five years; complete biographical information for the proposed candidate; and a description of the proposed candidate’s qualifications as a director. Any such submission must be accompanied by the written consent of the proposed nominee to be named as a nominee and to serve as a director if elected.

Board Diversity

Our Board monitors the mix of skills and experience of its directors to help ensure it has the necessary tools to perform its oversight function effectively. The Board fully appreciates the value of a diversity of viewpoints, background and experiences as important to the selection of directors to enhance the Board’s cognitive diversity and quality of dialogue in the Boardroom.

We believe that our current directors possess diverse professional experiences, skills and backgrounds, in addition to, among other characteristics, high standards of personal and professional ethics and valuable knowledge of our business and our industry.

Board’s Oversight of Strategy

Our Board is deeply engaged and involved in overseeing our long-range strategy, including evaluating key market opportunities and trends, the company’s strengths, weaknesses, opportunities and threats, external changes affecting the company and industry and competitive developments. This also includes aspects of our environmental, social and governance (“ESG”) initiatives that relate to our strategy. Our Board’s oversight of risk is another integral component of the Board’s oversight and engagement on strategic matters. Strategy-related matters are regularly discussed at Board meetings and, when relevant, at Committee meetings. Matters of strategy also inform committee-level discussions of many issues, including enterprise risk. Engagement of the Board on these issues and other matters of strategic importance continues in between meetings, including through updates to the Board on significant items and discussions between the Chief Executive Officer and our Chairman on a periodic basis. Each director is expected to and does bring to bear their own talents, insights, and experiences to these strategy discussions.

Cybersecurity and Data Privacy Oversight

Our Board addresses the company’s cybersecurity risk management as part of its general oversight function. The Audit Committee is responsible for reviewing the company’s guidelines and policies with respect to risk assessment, risk management and mitigation of risks from cybersecurity threats.

Our cybersecurity risk assessment and management processes are implemented and maintained by certain company management, including our Head of IT and our Chief Operation Officer. Our Head of IT has over 30 years of IT experience in both public and private companies in the biotech pharmaceutical industry and is a Microsoft Certified Professional in Microsoft technologies. He has experience in evaluating and implementing tools and technologies that enable defense and response capabilities, developing critical cybersecurity procedures, training, and awareness programs. The Head of IT reports directly to our Chief Operating Officer who provides executive oversight of cybersecurity risk management and has over 30 years of experience with public companies in the biotech pharmaceutical industry overseeing operational and enterprise risk management processes, including the review of cybersecurity risks and mitigation strategies with management. In addition, our Chief Operating Officer has a Cybersecurity for Directors certificate from the Corporate Governance Institute

Management is also responsible for hiring appropriate personnel, helping to integrate cybersecurity risk considerations into the company’s overall risk management strategy, and communicating key priorities to relevant personnel. The Head of IT and Chief Operating Officer are responsible for helping prepare the company for cybersecurity incidents, approving cybersecurity processes, and reviewing security assessments and other security-related reports.

Our cybersecurity incident response processes are designed to escalate certain cybersecurity incidents to members of management depending on the circumstances and designated risk level, including the Chief Executive Officer, Principal Accounting Officer and/or full Executive Leadership Team, who participates in our disclosure controls and procedures. The Head of IT and Chief Operating Officer work with the company’s incident response team to help the company mitigate and remediate cybersecurity incidents of which they are notified. Notifications may be received via automated alerts and reports from electronic system monitoring tools that we have implemented to assist in the protection against phishing, malware, business email compromise, ransomware, and other cyberthreats, or may be submitted directly to our Head of IT from employees who believe they may have received a suspicious threat. In addition, the company’s incident response processes include reporting to the Audit Committee for certain cybersecurity incidents.

The Audit Committee receives periodic reports from the Head of IT and Chief Operating Officer concerning the company’s significant cybersecurity threats and risk and the processes the company has implemented to address them. The Audit Committee also receives summaries or presentations related to the company’s information systems and data and cybersecurity threats, risk and mitigation.

Stockholder Communications with The Board of Directors

The Board has adopted a formal process by which stockholders may communicate with the Board or any of its directors. Stockholders who wish to communicate with the Board may do so by sending written communications addressed to the Secretary of Equillium, Inc., 2223 Avenida de la Playa, Suite 105, La Jolla, California 92037. These communications will be reviewed by the Secretary of Equillium who will determine whether the communication is appropriate for presentation to the Board or the relevant director. The purpose of this screening is to allow the Board to avoid having to consider irrelevant or inappropriate communications (such as advertisements, solicitations and hostile communications).

Code of Business Conduct and Ethics

We have adopted a Code of Business Conduct and Ethics that applies to all officers, directors and employees, including its principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. The Code of Business Conduct and Ethics is available on our website at www.equilliumbio.com. The information on our website is not incorporated by reference into this Proxy Statement or our Annual Report on Form 10-K for the fiscal year ended December 31, 2025. If we make any substantive amendments to the Code of Business Conduct and Ethics or grants any waiver from a provision of the code to any executive officer or director, we will promptly disclose the nature of the amendment or waiver on its website or in a current report on Form 8-K.

Insider Trading Policy

We have adopted an insider trading policy governing the purchase, sale, and/or other dispositions of our securities by directors, officers and employees that is designed to promote compliance with insider trading laws, rules and regulations, as well as procedures designed to further the foregoing purposes. A copy of our insider trading policy is filed as an exhibit to our Annual Report on Form 10-K for our fiscal year ended December 31, 2025. In addition, it is our intent to comply with applicable laws and regulations relating to insider trading.

Hedging and Pledging Policy

Under our insider trading policy, our directors, officers, other employees and consultants may not hedge their ownership of our stock, including but not limited to trading in options, puts, calls, or other derivative instruments related to our stock. Additionally, directors, officers, other employees and consultants may not purchase our stock on margin, borrow against our stock held in a margin account, or pledge our stock as collateral for a loan.

PROPOSAL 2: APPROVAL OF AN AMENDMENT TO OUR AMENDED AND

RESTATED CERTIFICATE OF INCORPORATION TO EFFECT A REVERSE STOCK

SPLIT OF OUR COMMON STOCK

Background

Our Board of Directors has unanimously approved a series of alternate amendments to our Amended and Restated Certificate of Incorporation, which would:

Accordingly, effecting a Reverse Stock Split would reduce the number of outstanding shares of our common stock. The effectiveness of any one of these amendments and the abandonment of the other amendments, or the abandonment of all of these amendments, will be determined by our Board of Directors following the Annual Meeting and prior to December 31, 2027. Our Board of Directors has recommended that these proposed amendments be presented to our stockholders for approval.

Our stockholders are being asked to approve these proposed amendments pursuant to Proposal 2, and to grant authorization to our Board of Directors to determine, at its option, whether to implement a Reverse Stock Split, including its specific timing and ratio.

Should we receive the required stockholder approvals for Proposal 2, our Board of Directors will have the sole authority to elect, at any time on or prior to December 31, 2027 and without the need for any further action on the part of our stockholders, whether to effect a Reverse Stock Split and the number of whole shares of our common stock, between and including two (2) and twenty (20), that will be combined into one share of our common stock.

Notwithstanding approval of Proposal 2 by our stockholders, our Board of Directors may, at its sole option, abandon the proposed amendments and determine prior to the effectiveness of any filing with the Secretary of State of the State of Delaware not to effect any Reverse Stock Split, as permitted under Section 242(c) of the General Corporation Law of the State of Delaware. If our Board of Directors does not implement a Reverse Stock Split on or prior to December 31, 2027, stockholder approval would again be required prior to implementing any Reverse Stock Split.

By approving Proposal 2, our stockholders will: (a) approve a series of alternate amendments to our Amended and Restated Certificate of Incorporation pursuant to which any whole number of outstanding shares of common stock between and including two (2) and twenty (20) could be combined into one share of common stock; and (b) authorize our Board of Directors to file only one such amendment, as determined by the Board at its sole option, and to abandon each amendment not selected by the Board. Our Board of Directors may also elect not to undertake any Reverse Stock Split and therefore abandon all amendments.

Approval of Reverse Stock Split of our Common Stock (Proposal 2)

Our Board of Directors has adopted and is recommending that our stockholders approve a series of alternate amendments to our Amended and Restated Certificate of Incorporation to effect a Reverse Stock Split. The text of the proposed form of Certificate of Amendment to our Amended and Restated Certificate of Incorporation, which we refer to as the Certificate of Amendment, is attached hereto as Appendix A.

We are proposing that our Board of Directors have the discretion to select the Reverse Stock Split ratio from within a range between and including 1-for-2 and 1-for-20, rather than proposing that stockholders approve a specific ratio at this time, in order to give our Board of Directors the flexibility to implement a Reverse Stock Split at a ratio that reflects the Board’s then-current assessment of the factors described below under “Criteria to be Used for Determining Whether to Implement the Reverse Stock Split.” If the Board decides to implement a Reverse Stock Split, we will file the Certificate of Amendment with the Secretary of State of the State of Delaware and the Reverse Stock Split will be effective on the business day following the filing of the Certificate of Amendment with the Secretary of

State of the State of Delaware, or such later time as is chosen by the Board and set forth in the Certificate of Amendment. Except for adjustments that may result from the treatment of fractional shares as described below, each of our stockholders will hold the same percentage of our outstanding common stock immediately following the Reverse Stock Split as such stockholder holds immediately prior to the Reverse Stock Split.

Reasons for Reverse Stock Split

To potentially improve the marketability and liquidity of our common stock. Our Board of Directors believes that the increased market price of our common stock expected as a result of implementing a Reverse Stock Split could improve the marketability and liquidity of our common stock and encourage interest and trading in our common stock.

Criteria to be Used for Determining Whether to Implement Reverse Stock Split

In determining whether to implement the Reverse Stock Split and which Reverse Stock Split ratio to implement, if any, following receipt of stockholder approval of Proposal 2, our Board of Directors may consider, among other things, various factors, such as:

Certain Risks and Potential Disadvantages Associated with Reverse Stock Split

We cannot assure you that the proposed Reverse Stock Split will increase our stock price for a sustained period and, if applicable, have the desired effect of maintaining compliance with Nasdaq Marketplace Rules. However, the effect of the Reverse Stock Split upon the market price of our common stock cannot be predicted with any certainty, and the history of similar reverse stock splits for companies in like circumstances is varied, particularly since some

investors may view a reverse stock split negatively. It is possible that the per share price of our common stock after the Reverse Stock Split will not rise in proportion to the reduction in the number of shares of our common stock outstanding resulting from the Reverse Stock Split and the Reverse Stock Split may not result in a per share price that would attract brokers and investors who do not trade in lower priced stocks. In addition, although we believe the Reverse Stock Split may enhance the desirability of our common stock to certain potential investors, we cannot assure you that, if implemented, our common stock will be more attractive to institutional and other long-term investors. Even if we implement the Reverse Stock Split, the market price of our common stock may decrease due to factors unrelated to the Reverse Stock Split. In any case, the market price of our common stock may also be based on other factors which may be unrelated to the number of shares outstanding, including our future performance. If the Reverse Stock Split is consummated and the trading price of the common stock declines, the percentage decline as an absolute number and as a percentage of our overall market capitalization may be greater than would occur in the absence of the Reverse Stock Split. Additionally, we may be delisted due to a failure to meet continued listing requirements, including Nasdaq requirements related to the minimum number of shares that must be in the public float, the minimum market value of the public float and the minimum number of “round lot” holders.

The proposed Reverse Stock Split may decrease the liquidity of our common stock and result in higher transaction costs. The liquidity of our common stock may be negatively impacted by a Reverse Stock Split, given the reduced number of shares that would be outstanding after the Reverse Stock Split, particularly if the stock price does not increase as a result of the Reverse Stock Split. In addition, if a Reverse Stock Split is implemented, it will increase the number of our stockholders who own “odd lots” of fewer than 100 shares of common stock. Brokerage commission and other costs of transactions in odd lots are generally higher than the costs of transactions of more than 100 shares of common stock. Accordingly, a Reverse Stock Split may not achieve the desired results of increasing marketability and liquidity of our common stock described above.

The effective increase in the authorized number of shares of our common stock as a result of the Reverse Stock Split could have anti-takeover implications. The implementation of a Reverse Stock Split will result in an effective increase in the authorized number of shares of our common stock available for issuance, which could, under certain circumstances, have anti-takeover implications. The additional shares of common stock that would become available for issuance if this Proposal 2 is approved and a Reverse Stock Split is implemented could be used by us to oppose a hostile takeover attempt or to delay or prevent changes in control or our management. For example, without further stockholder approval, the Board could adopt a “poison pill” which would, under certain circumstances related to an acquisition of our securities that is not approved by the Board, give certain holders the right to acquire additional shares of our common stock at a low price. The Board also could strategically sell shares of common stock in a private transaction to purchasers who would oppose a takeover or favor the current Board. Although this Proposal 2 has been prompted by business and financial considerations and not by the threat of any hostile takeover attempt (nor is the Board currently aware of any such attempts directed at us), stockholders should be aware that approval of this Proposal 2 could facilitate future efforts by us to deter or prevent changes in control, including transactions in which the stockholders might otherwise receive a premium for their shares over then current market prices.

Effects of Reverse Stock Split

After the effective date of any Reverse Stock Split that our Board of Directors elects to implement, each stockholder will own a reduced number of shares of common stock. However, any Reverse Stock Split will affect all of our stockholders uniformly and will not affect any stockholder’s percentage ownership interests in Equillium, except to the extent that the Reverse Stock Split results in any of our stockholders owning a fractional share as described below. Voting rights and other rights and preferences of the holders of our common stock will not be affected by a Reverse Stock Split (other than as a result of the payment of cash in lieu of fractional shares). For example, a holder of 2% of the voting power of the outstanding shares of our common stock immediately prior to a Reverse Stock Split would continue to hold 2% (assuming there is no impact as a result of the payment of cash in lieu of issuing fractional shares) of the voting power of the outstanding shares of our common stock immediately after such Reverse Stock Split. The number of stockholders of record will not be affected by a Reverse Stock Split (except to the extent that any stockholder holds only a fractional share interest and receives cash for such interest after such Reverse Stock Split).

The principal effects of a Reverse Stock Split will be that:

The following table contains approximate information, based on share information as of April 1, 2026, relating to our authorized and outstanding common stock based on the proposed Reverse Stock Split ratios (without giving effect to the treatment of fractional shares):

After the effective date of any Reverse Stock Split that our Board of Directors elects to implement, our common stock would have a new committee on uniform securities identification procedures (CUSIP) number, a number used to identify our common stock.

Our common stock is currently registered under Section 12(b) of the Exchange Act and we are subject to the periodic reporting and other requirements of the Exchange Act. The implementation of any proposed Reverse Stock Split will not affect the registration of our common stock under the Exchange Act. Our common stock would continue to be listed on The Nasdaq Capital Market under the symbol “EQ” immediately following the Reverse Stock Split, although it is likely that Nasdaq would add the letter “D” to the end of the trading symbol for a period of twenty trading days after the effective date of the Reverse Stock Split to indicate that the Reverse Stock Split had occurred.

Effective Date

The proposed Reverse Stock Split would become effective at 5:00 p.m., Eastern Time, on the business day following the filing of a Certificate of Amendment with the office of the Secretary of State of the State of Delaware, or such later date as is chosen by the Board and set forth in the Certificate of Amendment, which date we refer to in this Proposal 2 as the Effective Date. Except as explained below with respect to fractional shares, effective as of 5:00 p.m., Eastern Time, on the Effective Date, shares of common stock issued and outstanding immediately prior thereto will be combined, automatically and without any action on the part of us or our stockholders, into a fewer number of new shares of our common stock in accordance with the Reverse Stock Split ratio determined by our Board within the limits set forth in this Proposal 2.

Cash Payment In Lieu of Fractional Shares

No fractional shares of common stock will be issued as a result of any Reverse Stock Split. Instead, in lieu of any fractional shares to which a stockholder of record would otherwise be entitled as a result of the Reverse Stock Split, Equillium will pay cash (without interest) equal to such fraction multiplied by the average of the closing sales prices of the common stock on The Nasdaq Capital Market during regular trading hours for the five consecutive trading days immediately preceding the Effective Date (with such average closing sales prices being adjusted to give effect to the Reverse Stock Split). After the Reverse Stock Split, a stockholder otherwise entitled to a fractional interest will not have any voting, dividend or other rights with respect to such fractional interest except to receive payment as described above.

As of April 1, 2026, there were stockholders of record of our common stock. Upon stockholder approval of this Proposal 2, if our Board of Directors elects to implement the proposed Reverse Stock Split, stockholders owning, prior to the Reverse Stock Split, less than the number of whole shares of common stock that will be combined into one share of common stock in the Reverse Stock Split would no longer be stockholders. For example, if a stockholder held 5 shares of common stock immediately prior to the Reverse Stock Split and the Reverse Stock Split ratio selected by the Board was 1-for-10, then such stockholder would cease to be a stockholder of Equillium following the Reverse Stock Split and would not have any voting, dividend or other rights except to receive payment for the fractional share as described above. Based on our stockholders of record as of April 1, 2026, and assuming a Reverse Stock Split ratio of 1-for-20, we do not expect that cashing out fractional stockholders will reduce the number of stockholders of record. In addition, we do not intend for this transaction to be the first step in a series of plans or proposals of a “going private transaction” within the meaning of Rule 13e-3 of the Exchange Act.

Record and Beneficial Stockholders

If this Proposal 2 is approved by our stockholders and our Board of Directors elects to implement a Reverse Stock Split, stockholders of record holding all of their shares of our common stock electronically in book-entry form under the direct registration system for securities will be automatically exchanged by the exchange agent and will receive a transaction statement at their address of record indicating the number of new post-split shares of our common stock they hold after the Reverse Stock Split along with payment in lieu of any fractional shares. Non-registered stockholders holding common stock through a bank, broker or other nominee should note that such banks, brokers or other nominees may have different procedures for processing the Reverse Stock Split and making payment for fractional shares than those that would be put in place by us for registered stockholders. If you hold your shares with such a bank, broker or other nominee and if you have questions in this regard, you are encouraged to contact your nominee.

If this Proposal 2 is approved by our stockholders and our Board of Directors elects to implement a Reverse Stock Split, stockholders of record holding some or all of their shares in certificate form will receive a letter of transmittal from Equillium or its exchange agent, as soon as practicable after the Effective Date. Our transfer agent is expected

to act as “exchange agent” for the purpose of implementing the exchange of stock certificates. Holders of pre-Reverse Stock Split shares will be asked to surrender to the exchange agent certificates representing pre-Reverse Stock Split shares in exchange for post-Reverse Stock Split shares and payment in lieu of fractional shares (if any) in accordance with the procedures to be set forth in the letter of transmittal. No new post-Reverse Stock Split share certificates will be issued to a stockholder until such stockholder has surrendered such stockholder’s outstanding certificate(s) together with the properly completed and executed letter of transmittal to the exchange agent.

STOCKHOLDERS SHOULD NOT DESTROY ANY PRE-SPLIT STOCK CERTIFICATE AND SHOULD NOT SUBMIT ANY CERTIFICATES UNTIL THEY ARE REQUESTED TO DO SO.

Accounting Consequences

The par value per share of our common stock would remain unchanged at $0.0001 per share after any Reverse Stock Split. As a result, on the Effective Date, the stated capital on our balance sheet attributable to the common stock would be reduced proportionally, based on the actual Reverse Stock Split ratio, from its present amount, and the additional paid-in capital account would be credited with the amount by which the stated capital would be reduced. The net income or loss per share of common stock would be increased because there would be fewer shares of common stock outstanding. The Reverse Stock Split would be reflected retroactively in our financial statements. We do not anticipate that any other accounting consequences would arise as a result of any Reverse Stock Split.

No Appraisal Rights

Our stockholders are not entitled to dissenters’ or appraisal rights under the General Corporation Law of the State of Delaware with respect to the proposed alternate amendments to our Amended and Restated Certificate of Incorporation to allow for a Reverse Stock Split.

Material U.S. Federal Income Tax Consequences

The following is a summary of certain material U.S. federal income tax consequences of the Reverse Stock Split that are generally expected to be applicable to stockholders that hold their shares of common stock as capital assets within the meaning of Section 1221 of the U.S. Internal Revenue Code of 1986, as amended (the “Code”) (generally property held for investment). This summary is based upon the provisions of the Code, Treasury regulations promulgated thereunder, administrative rulings and judicial decisions, all as in effect as of the date hereof, and all of which are subject to change and differing interpretations, possibly with retroactive effect. Changes in these authorities or their interpretation may result in the U.S. federal income tax consequences of the Reverse Stock Split differing substantially from the consequences summarized below. This summary, except for the discussion under “Information Reporting and Backup Withholding” below, is limited to stockholders who are U.S. Holders (as defined below).

This summary is for general information purposes only and does not address all aspects of U.S. federal income taxation that may be relevant to U.S. Holders in light of their particular circumstances or to U.S. Holders that may be subject to special tax rules, including, without limitation: (i) persons subject to the alternative minimum tax; (ii) banks, insurance companies, or other financial institutions; (iii) tax-exempt organizations; (iv) dealers in securities or commodities; (v) regulated investment companies or real estate investment trusts; (vi) partnerships (including entities or arrangements treated as partnerships for U.S. federal income tax purposes and their partners or members); (vii) traders in securities that elect to use the mark-to-market method of accounting; (viii) persons whose “functional currency” is not the U.S. dollar; (ix) persons holding our common stock in a hedging transaction, “straddle,” “conversion transaction” or other risk reduction transaction; (x) persons who acquired our common stock in connection with employment or the performance of services; (xi) retirement plans; (xii) persons who are not treated as U.S. Holders for U.S. federal income tax purposes; or (xiii) certain former citizens or long-term residents of the United States.

In addition, this summary does not address: (a) the tax consequences of transactions effectuated before, after or at the same time as the Reverse Stock Split, whether or not they are in connection with the Reverse Stock Split; (b) any U.S. federal non-income tax consequences of the Reverse Stock Split, including estate, gift or other tax consequences; (c) any state, local or non-U.S. tax consequences of the Reverse Stock Split; (d) the Medicare contribution tax on net investment income, or (e) tax consequences to holders of options, warrants or similar rights to acquire our common stock. No ruling from the Internal Revenue Service (the “IRS”), or opinion of counsel, has been or will be requested in connection with the Reverse Stock Split. Stockholders should be aware that the IRS could adopt a position which could be sustained by a court contrary to that set forth in this discussion.

Accordingly, each stockholder should consult with such stockholder’s own tax advisor with respect to all of the potential tax consequences to such stockholder of the Reverse Stock Split.

For purposes of this discussion, a “U.S. Holder” means a beneficial owner of shares of our common stock that is any of the following:

If a partnership (including any entity or arrangement treated as a partnership for U.S. federal income tax purposes) holds shares of our common stock, the tax treatment of a partner in the partnership generally will depend upon the status of the partner and the activities of the partnership. Partnerships holding our common stock and the partners therein should consult their tax advisors regarding the tax consequences to them of the Reverse Stock Split.

EACH STOCKHOLDER SHOULD CONSULT ITS TAX ADVISORS WITH RESPECT TO THE PARTICULAR TAX CONSEQUENCES OF THE REVERSE STOCK SPLIT TO SUCH STOCKHOLDER.

Taxation of U.S. Holders

The Reverse Stock Split should constitute a “recapitalization” for U.S. federal income tax purposes. As a recapitalization, except as described below with respect to cash received in lieu of fractional shares, a U.S. Holder should not recognize gain or loss as a result of the Reverse Stock Split. With respect to any U.S. Holder who receives solely a reduced number of shares of common stock (i.e., no cash in lieu of a fractional share) as a result of the Reverse Stock Split, such U.S. Holder’s aggregate tax basis in the shares of the common stock received pursuant to the Reverse Stock Split should equal the U.S. Holder’s aggregate tax basis in the shares of the common stock surrendered, and such U.S. Holder’s holding period in the shares of the common stock received should include the holding period of the shares of the common stock surrendered. Treasury regulations promulgated under the Code provide detailed rules for allocating the tax basis and holding period of shares of common stock surrendered pursuant to the Reverse Stock Split to shares of common stock received pursuant to the Reverse Stock Split. U.S. Holders holding shares of common stock that were acquired on different dates and at different prices should consult their tax advisors regarding the allocation of the tax basis and holding period of such shares.

A U.S. Holder who receives cash in lieu of a fractional share of common stock pursuant to the Reverse Stock Split generally should recognize capital gain or loss in an amount equal to the difference, if any, between the amount of cash received and the portion of the U.S. Holder’s tax basis in the shares of common stock surrendered that is allocated to such fractional share of common stock. Such capital gain or loss generally should be long-term capital gain or loss if the U.S. Holder’s holding period for the common stock surrendered in the Reverse Stock Split exceeds one year at the time of the Reverse Stock Split. Long-term capital gains of non-corporate U.S. Holders are generally subject to preferential tax rates. There are limitations on the deductibility of capital losses under the Code. Such U.S. Holder’s aggregate tax basis in the reduced number of shares of common stock received pursuant to the Reverse Stock Split should equal the U.S. Holder’s aggregate tax basis in is old shares of common stock decreased by the basis allocated to the fractional share for which such U.S. Holder is entitled to receive cash, and the holding period of the reduced number of shares received will include the holding period of the old shares exchanged.

Information Reporting and Backup Withholding

Stockholders may be subject to information reporting with respect to any cash received in exchange for a fractional share interest in a new share in the Reverse Stock Split. Stockholders who are subject to information reporting and who do not provide a correct taxpayer identification number and other required information (such as by submitting a properly completed IRS Form W-9) may also be subject to backup withholding, at the applicable rate. Any amount withheld under such rules is not an additional tax and may be refunded or credited against the stockholder’s U.S. federal income tax liability, provided that the required information is properly furnished in a timely manner to the IRS.

The preceding discussion is intended only as a summary of certain material U.S. federal income tax consequences of the Reverse Stock Split. It is not a complete analysis or discussion of all potential tax effects that may be important to a particular holder. All holders of our common stock should consult their own tax advisors as to the specific tax consequences of the Reverse Stock Split to them, including record retention and tax-reporting requirements, and the applicability and effect of any federal, state, local and non-U.S. tax laws.

THE BOARD OF DIRECTORS RECOMMENDS THAT STOCKHOLDERS VOTE “FOR” THE APPROVAL OF A REVERSE STOCK SPLIT AS SET FORTH IN PROPOSAL 2.

PROPOSAL 3: RATIFICATION OF APPOINTMENT OF INDEPENDENT REGISTERED PUBLIC

ACCOUNTING FIRM

The Audit Committee has appointed Crowe LLP (“Crowe”) as our independent registered public accounting firm for the fiscal year ending December 31, 2026 and has further directed that management submit the selection of its independent registered public accounting firm for ratification by the stockholders at the Annual Meeting and recommended that stockholders ratify such selection. Representatives of Crowe are expected to be present at the Annual Meeting. They will have an opportunity to make a statement if they so desire and will be available to respond to appropriate questions.

Neither our amended and restated bylaws nor other governing documents or law require stockholder ratification of the appointment of Crowe as our independent registered public accounting firm. However, the Audit Committee is submitting the selection of Crowe to the stockholders for ratification as a matter of good corporate practice. If the stockholders fail to ratify the appointment, the Audit Committee will reconsider whether or not to retain that firm. Even if the selection is ratified, the Audit Committee in its discretion may direct the appointment of different independent auditors at any time during the year if they determine that such a change would be in the best interests of us and our stockholders.

Change in Auditor

As previously reported, on September 30, 2025, the Audit Committee dismissed KPMG LLP ("KPMG") as our independent registered public accounting firm.

KPMG’s audit reports on our Company’s consolidated financial statements as of and for the years ended December 31, 2024 and 2023 did not contain any adverse opinion or a disclaimer of opinion and were not qualified or modified as to uncertainty, audit scope or accounting principles, except as follows: KPMG’s report on our consolidated financial statements as of and for the years ended December 31, 2024 and 2023 contained a separate paragraph stating that “The accompanying consolidated financial statements have been prepared assuming that we will continue as a going concern. As discussed in Note 1 to the consolidated financial statements, the Company has suffered significant operating losses and negative cash flows from operations that raise substantial doubt about its ability to continue as a going concern. Management’s plans in regard to these matters are also described in Note 1. The consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.”

During our fiscal years ended December 31, 2024 and 2023 and the subsequent interim period through September 30, 2025: (1) there were no “disagreements” (as defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions to Item 304) with KPMG on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedure, which disagreements, if not resolved to the satisfaction of KPMG, would have caused KPMG to make reference to the subject matter of such disagreements in connection with its reports on the consolidated financial statements for such periods and (2) there were no “reportable events” (as defined in Item 304(a)(1)(v) of Regulation S-K).

KPMG's letter to the Securities and Exchange Commission (the "SEC") stating its agreement with the statements in the two foregoing paragraphs was filed as an exhibit to our Current Report on Form 8-K dated October 6, 2025.

Principal Accountant Fees and Services

The following table represents aggregate fees billed to us by Crowe for the fiscal year ended December 31, 2025:

No fees were billed to us by Crowe in the fiscal year ended December 31, 2024. All fees described above were pre-approved by the Audit Committee.

In connection with the audit of our 2025 financial statements, we entered into an engagement agreement with Crowe on October 21, 2025 that sets forth the terms by which Crowe will perform audit services for us.

Former Principal Accountant Fees and Services

The following table represents aggregate fees billed to us by KPMG for the fiscal years ended December 31, 2025 and 2024:

Pre-Approval Policies and Procedures

The Audit Committee must pre-approve the audit and non-audit services rendered by our independent registered public accounting firm. Our Audit Committee pre-approved all such audit and permitted non-audit services in 2025.

The Audit Committee has considered whether the provision of non-audit services was compatible with maintaining the independence of KPMG and concluded that the provision of such services was compatible with maintaining the independence of the firm.

Report of the Audit Committee of the Board of Directors*

The Audit Committee has reviewed and discussed the audited consolidated financial statements for the fiscal year ended December 31, 2025 with our management. The Audit Committee has discussed with the independent registered public accounting firm the matters required to be discussed under the applicable requirements of the Public Company Accounting Oversight Board (“PCAOB”) and the Securities and Exchange Commission. The Audit Committee has also received the written disclosures and the letter from the independent registered public accounting firm required by applicable requirements of the PCAOB regarding the independent registered public accounting firm’s communications with the Audit Committee concerning independence, and has discussed with the independent registered public accounting firm the accounting firm’s independence. Based on the foregoing, the Audit Committee has recommended to the Board that the audited consolidated financial statements be included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2025.

Martha J. Demski (Chair)

Charles McDermott

Barbara Troupin, M.D.

* The material in this report is not “soliciting material,” is not deemed “filed” with the SEC and is not to be incorporated by reference in any of our filings under the Exchange Act or the Securities Act of 1933, as amended (the "Securities Act"), whether made before or after the date hereof and irrespective of any general incorporation language in any such filing.

THE BOARD OF DIRECTORS RECOMMENDS

A VOTE “FOR” PROPOSAL 3.

proposal 4: APPROVAL OF INCREASE IN NUMBER OF AUTHORIZED SHAres OF COMMON STOCK

The Board is requesting stockholder approval of an amendment to the Company’s amended and restated Certificate of Incorporation to increase the Company’s authorized number of shares of common stock from 200,000,000 shares to 400,000,000 shares.

The additional common stock to be authorized by adoption of the amendment would have rights identical to the currently outstanding common stock of the Company. Adoption of the proposed amendment and issuance of the common stock would not affect the rights of the holders of currently outstanding common stock of the Company, except for effects incidental to increasing the number of shares of the Company’s common stock outstanding, such as dilution of the earnings per share and voting rights of current holders of common stock. If the amendment is adopted, it will become effective upon filing of a Certificate of Amendment of the Company’s amended and restated Certificate of Incorporation with the Secretary of State of the State of Delaware. The text of the proposed Certificate of Amendment of the Amended and Restated Certificate of Incorporation is attached hereto as Appendix B.

In addition to the shares of common stock outstanding on April 1, 2026, the Board has reserved shares for grants of restricted stock, issuance upon exercise of options and rights and other equity awards granted under the Company’s 2018 Equity Incentive Plan, (the “2018 Plan “) 2018 Employee Stock Purchase Plan (“ESPP”), and 2024 Inducement Plan (the “Inducement Plan” and together with the 2018 Plan and ESPP, the “Plans”), and up to approximately 80,428 shares of common stock which may be issued upon the exercise of outstanding warrants at an exercise price of $3.73 per share, approximately 48,515,298 shares of common stock which may be issued upon the exercise of outstanding pre-funded warrants to purchase common stock at an exercise price of $0.0001 per share and 35,087,717 shares of common stock (or pre-funded warrants in lieu thereof) issuable pursuant to that certain Securities Purchase Agreement dated August 10, 2025, by and among the Company and the investors who are parties thereto, at a price per share of $0.57.

Although, at present, the Board has no other plans to issue the additional shares of common stock, it desires to have the shares available to provide additional flexibility to use its capital stock for business and financial purposes in the future. The additional shares may be used for various purposes without further stockholder approval. These purposes may include raising capital; providing equity incentives to employees, officers or directors; establishing strategic relationships with other companies; expanding the Company’s business or product lines through the acquisition of other businesses or products; and other purposes.

The additional shares of common stock that would become available for issuance if the proposal were adopted could also be used by the Company to oppose a hostile takeover attempt or to delay or prevent changes in control or management of the Company. For example, without further stockholder approval, the Board could strategically sell shares of common stock in a private transaction to purchasers who would oppose a takeover or favor the current Board. Although this proposal to increase the authorized common stock has been prompted by business and financial considerations and not by the threat of any hostile takeover attempt (nor is the Board currently aware of any such attempts directed at the Company), nevertheless, stockholders should be aware that approval of the proposal could facilitate future efforts by the Company to deter or prevent changes in control of the Company, including transactions in which the stockholders might otherwise receive a premium for their shares over then current market prices.

THE BOARD OF DIRECTORS RECOMMENDS

A VOTE “FOR” APPROVAL OF INCREASE IN NUMBER OF AUTHORIZED SHARES OF COMMON STOCK

(PROPOSAL 4)

EXECUTIVE OFFICERS

Set forth below is biographical information for each of our executive officers as of the record date, other than Mr. Steel, whose biographical information is set forth above under “Election of Directors”:

Stephen Connelly, Ph.D., 44, has served as our Chief Scientific Officer since January 2018 and as a member of our Board from March 2017 to September 2025. On September 30, 2025, the Board appointed Dr. Connelly as the Company's President. Dr. Connelly is a co-founder of Equillium and served as a consultant from March 2017 until January 2018. Dr. Connelly served as a principal at BioMed Ventures, an investment firm owned by BioMed Realty, LP, from March 2016 until March 2017. From March 2014 to March 2016, Dr. Connelly served as the Director of Business Development and Therapeutic Alliances at aTyr Pharma, Inc., a publicly-held biotechnology company. Dr. Connelly has broad experience in conducting novel and innovative research and has published over 30 original scientific papers and patents. Dr. Connelly received a B.S. in Medicinal Chemistry and a Ph.D. in Biological Chemistry from the University of Exeter, United Kingdom, and an M.B.A. from the Rady School at University of California, San Diego.

Christine Zedelmayer, 56, has served as our Chief Operating Officer since January 2020. Ms. Zedelmayer served as our Vice President of Operations from February 2018 through December 2019. Ms. Zedelmayer currently serves as a strategic advisor to the Office of Economic Development at the University of Nevada, Las Vegas. Ms. Zedelmayer owns and was previously principal consultant at Centerra Consulting, LLC, a project management and investor relations consulting firm focused on life sciences, from 2012 to 2018, where she led strategic business development projects for clients and served as head of investor relations for a variety of medical device companies. Prior to Centerra, from 2003 to 2012, Ms. Zedelmayer held a variety of roles at Amylin Pharmaceuticals, Inc., a publicly-held biopharmaceutical company, including Senior Director of Alliance Management, where she led the global collaboration with Eli Lilly and as Executive Director of Investor Relations. Earlier in her career, Ms. Zedelmayer held positions of increasing responsibility in engineering and program management at Amgen, Inc., a publicly held biopharmaceutical company, Ligand Pharmaceuticals, a publicly-held pharmaceutical company and at Hybritech, a diagnostics subsidiary of Eli Lilly & Company. Ms. Zedelmayer received her B.S. in Electrical Engineering from San Diego State University and an M.B.A. with Finance emphasis from California Lutheran University.

EXECUTIVE AND DIRECTOR COMPENSATION

We are a “smaller reporting company” under Item 10 of Regulation S-K promulgated under the Exchange Act, and the following compensation disclosure is intended to comply with the requirements applicable to smaller reporting companies. Although the rules allow us to provide less detail about our executive compensation program, the Compensation Committee is committed to providing the information necessary to help stockholders understand its executive compensation-related decisions. Accordingly, this section includes supplemental narratives that describe the 2025 executive compensation program for our named executive officers.

Our named executive officers for the year ended December 31, 2025, which consist of our principal executive officer and our two other most highly compensated executive officers, were:

Executive Summary

Our business strategy is to develop high-impact, novel therapeutics to treat autoimmune and inflammatory disorders, and by so doing, deliver long-term value for our stockholders. The Compensation Committee believes that it is critical to attract, retain, and incentivize highly skilled executive officers to execute on our business strategy. Accordingly, our executive compensation program is structured to provide a competitive level of base cash compensation, with the opportunity to earn meaningfully more only upon successful performance. This structure motivates our executives to achieve results for our business and value for our stockholders over the long-term because our executives are only paid cash bonuses to the extent we achieve our goals, and only realize value for stock options if our stock price increases over a multi-year period and the executive remains employed with us over that period.

Compensation Committee Role

The Compensation Committee is comprised of independent, non-employee members of the Board of Directors and is responsible for evaluating and determining the compensation paid to the named executive officers. The Compensation Committee retains an independent compensation consultant to assist it in making executive compensation decisions.

For 2025, the Compensation Committee engaged Aon as its independent compensation consultant. In making 2025 compensation decisions, the Compensation Committee reviewed market data for each named executive officer’s position, compiled by Aon, from the following peer group of companies for 2025:

The 2025 peer group was recommended by Aon and compiled by selecting companies with as many of the following parameters as possible: publicly-traded, pre-commercial stage biopharmaceutical companies, with an emphasis on companies focused on autoimmune and/or immunology therapeutic areas, and a preference for companies located in biotechnology hub locations, in particular San Diego, with market capitalizations generally under $100 million, trailing-twelve-month cash and cash equivalents of less than $100 million and headcounts below 150.

2025 Compensation Actions

Chief Executive Officer’s Realizable Compensation

The Compensation Committee believes that given the significant proportion that variable or “at-risk” pay represents of our executives’ total compensation program, realizable pay is an important measure to review in analyzing the alignment between our executive compensation program and our business/stock price performance. Compensation that is actually realizable by our Chief Executive Officer helps our Compensation Committee, Board of Directors and investors understand the sensitivity of our compensation program to our actual financial and stock performance and illustrates the alignment of our compensation program with stockholder interests. Our Chief Executive Officer’s 2025 realizable pay was 63% lower than his total compensation reported in the Summary Compensation Table. Realizable compensation, for purposes of the discussion in this paragraph, includes base salary and all bonuses or other non-equity incentive compensation paid or earned in 2025 plus the intrinsic value of equity awards granted in 2025 (calculated as of the last day of our 2025 fiscal year, and including both vested and unvested equity). Reported pay reflects the amount reported in the Summary Compensation Table, below.

Our Executive Compensation Practices

Summary Compensation Table

The following table shows the compensation earned by our named executive officers for the fiscal years ended December 31, 2025 and 2024.

Compensation Program Overview

Our compensation program for executive officers is designed to encourage our management team to achieve our short-term and long-term corporate objectives while effectively managing business risks and challenges. We provide what we believe is a competitive total compensation package to our management team through a combination of base salary, an annual performance-based bonus opportunity and long-term equity-based incentives.

Annual Base Salary

The base salaries of all of our named executive officers are reviewed from time to time and adjusted when our Board of Directors or Compensation Committee determines an adjustment is appropriate. The 2025 annual base salaries for our named executive officers are provided below.

(1) Reflects base salaries as in effect as of August 2025. Prior to August 2025, the base salaries remained at the 2024 base salary level as described above in “2025 Compensation Actions.”

Bonus

In August 2025, the Board approved one-time spot bonuses to each of our named executive officers in recognition of the Company's completion of its fundraising goal in the third quarter of 2025 and to support retention during a period of organizational transition.

The 2025 bonuses for our named executive officers are provided below:

Non-Equity Incentive Plan Compensation

In keeping with our pay-for-performance philosophy, the annual performance-based bonus that can be earned by each named executive officer is variable and at risk due to its dependency on the performance of the company as well as the company’s overall financial condition. Prior to the start of each calendar year, the Chief Executive Officer develops, with input from our named executive officers and the rest of the executive leadership team, our annual corporate goals, including recommended weightings for each goal. The weighting for each corporate goal depends on its importance and business value for the company and our stockholders. In addition, there may be certain upside goals such that the total goal achievement could be greater than 100% of target. The Chief Executive Officer submits the corporate goals and recommended weightings to the Compensation Committee and the Board for their review and approval. The Compensation Committee and Board review the corporate goals and weightings and may modify them as they deem appropriate prior to approval.

At the end of the year, the Compensation Committee assesses the extent to which each annual corporate goal has been attained, including, in its discretion, considering additional achievements by the Company not originally set forth in the annual corporate goals. Once so determined, the Compensation Committee then determines payouts against each named executive officer’s target bonus.

The Compensation Committee sets the target bonus opportunity for a new year at the end of the prior year, based primarily on benchmark data provided by Aon, including target bonus percentages and total cash compensation of similar positions at our peer companies, and considering the totality of compensation to potentially be provided to our named executive officers. The target bonus opportunity as a percentage of 2025 base salary for each of our named executive officers was as follows:

The target bonus percentage for our Chief Executive Officer changed from 75% to 60%, but did not change in 2025 compared to 2024 for the remaining named executive officers.

Our corporate goals for 2025, the weighting of each goal, and achievement against such goal, as determined by our Compensation Committee in September 2025, were as follows:

Based on the company’s performance across all of its goals in 2025 as summarized above, the Compensation Committee determined that 100% of the corporate goals had been achieved in 2025.

Equity-Based Incentive Awards

Our equity-based incentive awards are designed to align the interests of our employees and consultants with those of our stockholders.

We have historically granted stock options as the long-term compensation incentive vehicle for our named executive officers. However, we may grant equity awards at such times as our Board and/or Compensation Committee determines appropriate. Other than our founders, our executive officers generally are awarded an initial grant in the form of a stock option in connection with their commencement of employment.

Prior to our initial public offering in October 2018, we granted all stock options pursuant to our 2017 Equity Incentive Plan (“2017 Plan”). Following our initial public offering, we have granted and will grant equity incentive awards under the terms of our 2018 Equity Incentive Plan (“2018 Plan”) and 2024 Inducement Plan ("Inducement Plan"). The terms of the 2017 Plan, the 2018 Plan and the Inducement Plan are described below under “—Equity Benefit Plans.”

All options are granted with an exercise price per share that is no less than the fair market value of our common stock on the date of grant of such award. Our stock option awards generally vest over a four-year period subject to continued service and may be subject to acceleration of vesting and exercisability under certain termination and change in control events. See “— Outstanding Equity Awards at Fiscal Year-End.”

In January 2025, the Compensation Committee granted options to purchase 410,000 shares, 175,000 shares and 175,000 shares of our common stock to Mr. Steel, Dr. Connelly and Ms. Zedelmayer, respectively, each at an exercise price of $0.7688 per share. In light of the significant dilution caused by the August 2025 capital raise, to ensure our employees, including our named executive officers, remained sufficiently incentivized both on a short term and long term basis, the Compensation Committee granted additional options to our employees. The options granted to our named executive officers were for 1,695,000 shares, 1,025,000 shares and 725,000 shares of our common stock to Mr. Steel, Dr. Connelly and Ms Zedelmayer, respectively, each at an exercise price of $1.74 per share. Each of the options vests as to 25% of the shares on the first anniversary of the grant date with the balance of shares vesting in equal monthly installments over the remaining 36 months, subject to the respective named executive officer’s continued

service with us and subject to full acceleration of all of the shares in the event the respective named executive officer is terminated by us without cause or the officer resigns for good reason, in each case within 12 months after a change in control.

Agreements with our Named Executive Officers

We have entered into offer letter agreements with each of our named executive officers which are described below. For a discussion of the severance pay and other benefits available in connection with a termination of employment and/or a change in control under the arrangements with our named executive officers, please see “—Potential Payments Upon Termination or Change in Control” below. In addition, each of our named executive officers is eligible to participate in the employee benefit plans generally available to our employees.

Bruce D. Steel. In June 2018, we entered into an offer letter with Mr. Steel, which was amended in January 2020 and which governs the terms of his employment with us. The offer letter provides for an initial annual base salary and eligibility for an annual performance-based bonus, based on the attainment of individual and corporate objectives to be determined and approved by us.

Stephen Connelly, Ph.D. In June 2018, we entered into an amended and restated offer letter with Dr. Connelly, which governs the terms of his employment with us. The offer letter provides for an initial annual base salary and eligibility to receive an annual performance-based bonus, based on the attainment of individual and corporate objectives to be determined and approved by us.

Christine Zedelmayer. In January 2018, we entered into an offer letter with Ms. Zedelmayer, which was amended in January 2020 and which governs the terms of her employment with us. The offer letter provides for an initial annual base salary and eligibility to receive an annual performance-based bonus, based on the attainment of individual and corporate objectives to be determined and approved by us.

Potential Payments and Benefits upon Termination or Change in Control

Each of our named executive officer’s employment is at will and may be terminated by us at any time. Regardless of the manner in which the named executive officer’s service terminates, such named executive officer is entitled to receive any and all accrued but unpaid amounts earned during the officer’s term of service, including unpaid salary, as applicable.

In addition, the offer letter agreements with each of Mr. Steel, Dr. Connelly and Ms. Zedelmayer each provide that, if we terminate such named executive officer’s employment without cause, the named executive officer is entitled to receive (i) continuation of then-current base salary for six months and (ii) payment of premiums for group health insurance COBRA continuance coverage for six months or, if earlier, the date on which the named executive officer becomes eligible to receive comparable benefits from another employer.

Additionally, if we terminate the named executive officer’s employment without cause within one month prior to, or within 12 months following, certain change of control and asset sale transactions, the named executive officer is entitled to receive (i) continuation of then-current base salary for 12 months, (ii) an amount equal to the applicable named executive officer’s target annual bonus and (iii) payment of the premiums for group health insurance COBRA continuance coverage for 12 months or, if earlier, the date on which the named executive officer becomes eligible to receive comparable benefits from another employer.

In each case, the severance benefits are conditioned upon the execution and non-revocation of a general release of claims by the applicable named executive officer in a form provided by us.

Our named executive officers are also entitled to full acceleration of all of the shares subject to their then-outstanding options in the event the respective named executive officer is terminated by us without cause or the officer resigns for certain good reasons, in each case within 12 months after a change in control.

Outstanding Equity Awards at Fiscal Year-End

The following table sets forth certain information regarding equity awards granted to our named executive officers that remain outstanding as of December 31, 2025:

Option Repricings

There were no repricings or cancellations of any of our named executive officers’ outstanding equity awards during the fiscal year ended December 31, 2025. We did not engage in modifications to any of our named executive officers’ outstanding equity awards during the fiscal year ended December 31, 2025.

Perquisites Health, Welfare and Retirement Benefits

Our named executive officers, during their employment with us, are eligible to participate in our employee benefit plans, including our medical, dental, group term life, disability and accidental death and dismemberment insurance plans, in each case on the same basis as all of our other employees. In addition, we provide a 401(k) plan to our employees, including our named executive officers, as discussed in the section below entitled “—401(k) Plan.”

We generally do not provide perquisites or personal benefits to our named executive officers, except in limited circumstances. We do, however, pay the premiums for medical, dental, group term life, disability and accidental death and dismemberment insurance for all of our employees, including our named executive officers. Our Board may elect to adopt qualified or nonqualified benefit plans in the future if it determines that doing so is in our best interests.

401(k) Plan

We maintain a defined contribution employee retirement plan (“401(k) plan”) for our employees. Our named executive officers are eligible to participate in the 401(k) plan on the same basis as our other employees. The 401(k) plan is intended to qualify as a tax-qualified plan under Section 401(k) of the Code. The 401(k) plan provides that each participant may contribute up to the lesser of 100% of his or her compensation or the statutory limit, which was $23,500 for calendar year 2025. Participants that are 50 years or older can also make “catch-up” contributions, which in calendar year 2025 was up to an additional $18,750, depending on the age of the participant. We did not make matching contributions into the 401(k) plan on behalf of participants during our 2025 fiscal year. Participant contributions are held and invested, pursuant to the participant’s instructions, by the plan’s trustee.

Nonqualified Deferred Compensation

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

Securities Authorized for Issuance under Equity Compensation Plans

The following table provides certain information with respect to all of our equity compensation plans in effect as of December 31, 2025.

Clawbacks

As a public company, if we are required to restate our financial results due to our material noncompliance with any financial reporting requirements under the federal securities laws as a result of misconduct, executive officers including the Chief Executive Officer and Chief Financial Officer may be legally required to reimburse us for any bonus or other incentive-based or equity-based compensation they received that was based on the originally reported and restated financial results in accordance with the provisions of section 304 of the Sarbanes-Oxley Act of 2002, as amended. Additionally, we have implemented a Dodd-Frank Act-compliant clawback policy, as required by SEC rules.

Equity Benefit Plans

2018 Equity Incentive Plan

Our Board adopted our 2018 Plan in October 2018 and our stockholders approved our 2018 Plan in October 2018. The 2018 Plan became effective on October 11, 2018 in connection with our initial public offering. The 2018 Plan is a successor to and continuation of our 2017 Plan. No further grants will be made under the 2017 Plan.

Our Board approved an amended 2018 Plan in March 2025 and our stockholders approved the amended 2018 Plan in May 2025. The Amended 2018 Plan contains the following material changes from the 2018 Plan:

•Increase Share Reserve. The maximum number of shares of our common stock that may be issued under the Amended 2018 Plan was increased to 13,722,626 shares (which was an increase of 1,781,000 shares over the maximum number of shares of our common stock that could be issued under the 2018 Plan before the amendment).

•Increase ISO Limit. The maximum number of shares of our common stock that may be issued upon the exercise of incentive stock options under the Amended 2018 Plan was increased to 27,445,252 (which is an increase of 20,755,933 shares over the maximum under the 2018 Plan before the amendments).

Our 2018 Plan, as amended (the "2018 Plan") provides for the grant of incentive stock options (“ISOs”), within the meaning of Section 422 of the Code, to employees, including employees of any parent or subsidiary, and for the grant of nonstatutory stock options (“NSOs”), stock appreciation rights, restricted stock awards, restricted stock unit awards, performance stock awards, performance cash awards and other forms of stock awards to employees, directors and consultants, including employees and consultants of our affiliates.

Our Compensation Committee administers our 2018 Plan and is referred to as the “plan administrator” herein. Our Board or Compensation Committee may also delegate certain limited authority to one or more of our officers.

ISOs and NSOs are granted under stock option agreements adopted by the plan administrator. The plan administrator determines the exercise price for stock options, within the terms and conditions of the 2018 Plan, provided that the exercise price of a stock option generally cannot be less than 100% of the fair market value of our common stock on the date of grant. Options granted under the 2018 Plan vest at the rate specified in the stock option agreement as determined by the plan administrator.

The plan administrator determines the term of stock options granted under the 2018 Plan, up to a maximum of 10 years. Unless the terms of an optionholder’s stock option agreement provide otherwise, if an optionholder’s service relationship with us or any of our affiliates ceases for any reason other than disability, death, or cause, the optionholder may generally exercise any vested options for a period of three months following the cessation of service. This period may be extended in the event that exercise of the option is prohibited by applicable securities laws or our insider trading policy. If an optionholder’s service relationship with us or any of our affiliates ceases due to death, or an optionholder dies within a certain period following cessation of service, the optionholder or a beneficiary may generally exercise any vested options for a period of 18 months following the date of death. If an optionholder’s service relationship with us or any of our affiliates ceases due to disability, the optionholder may generally exercise any vested options for a period of 12 months following the cessation of service. In the event of a termination for cause, options generally terminate upon the termination date. In no event may an option be exercised beyond the expiration of its term. The aggregate fair market value, determined at the time of grant, of our common stock with respect to ISOs that are exercisable for the first time by an award holder during any calendar year under all of our stock plans may not exceed $100,000. Options or portions thereof that exceed such limit will generally be treated as NSOs. No ISO may be granted to any person who, at the time of the grant, owns or is deemed to own stock possessing more than 10% of our total combined voting power or that of any of our parent or subsidiary corporations unless (1) the option exercise price is at least 110% of the fair market value of the stock subject to the option on the date of grant and (2) the term of the ISO does not exceed five years from the date of grant.

Our 2018 Plan provides that in the event of certain specified significant corporate transactions (or a change in control, as defined in the 2018 Plan), unless otherwise provided in an award agreement or other written agreement between us and the award holder, the plan administrator may take one or more of the following actions with respect to such stock awards:

The plan administrator is not obligated to treat all stock awards or portions of stock awards in the same manner and is not obligated to take the same actions with respect to all participants.

In the event of a change in control, the plan administrator may take any of the above-mentioned actions. Awards granted under the 2018 Plan may be subject to additional acceleration of vesting and exercisability upon or after a change in control as may be provided in the applicable stock award agreement or in any other written agreement between us or any affiliate and the participant, but in the absence of such provision, no such acceleration will automatically occur.

Our Board has the authority to amend, suspend, or terminate our 2018 Plan, provided that such action does not materially impair the existing rights of any participant without such participant’s written consent. Certain material amendments also require the approval of our stockholders. No ISOs may be granted after the tenth anniversary of the date our Board adopts our 2018 Plan. No stock awards may be granted under our 2018 Plan while it is suspended or after it is terminated.

2017 Equity Incentive Plan

Our Board and our stockholders approved our 2017 Plan in December 2017. No further awards may be granted under the 2017 Plan, and all outstanding awards granted under the 2017 Plan that are repurchased, forfeited, expire or are canceled will become available for grant under the 2018 Plan in accordance with its terms.

Our 2017 Plan provided for the grant of ISOs within the meaning of Section 422 of the Code to employees, including employees of any parent or subsidiary, and for the grant of NSOs, stock appreciation rights, restricted stock, restricted stock units and other forms of stock awards to employees, directors and consultants, including employees and consultants of our affiliates.

Our Compensation Committee administers our 2017 Plan and is referred to as the “plan administrator” herein.

If an optionholder’s service relationship with us or any of our affiliates ceases for any reason other than disability, death or cause, the optionholder may generally exercise any vested options for a period of up to three months following the cessation of service. This period may be extended in the event that exercise of the option is prohibited by applicable securities laws or our insider trading policy.

If an optionholder’s service relationship with us or any of our affiliates ceases due to death, or an optionholder dies within a certain period following cessation of service, the optionholder or a beneficiary may generally exercise any vested options for a period of up to 18 months following the date of death. If an optionholder’s service relationship with us or any of our affiliates ceases due to disability, the optionholder may generally exercise any vested options for a period of up to 12 months following the cessation of service. In the event of a termination for cause, options generally terminate upon the termination date. In no event may an option be exercised beyond the expiration of its term.

Our 2017 Plan provides that in the event of a “corporate transaction” (as defined in the 2017 Plan) unless otherwise provided in an award agreement or other written agreement between us and the award holder, the plan administrator may take one or more of the following actions with respect to such stock awards:

The plan administrator is not obligated to treat all stock awards or portions of stock awards in the same manner and is not obligated to treat all participants in the same manner.

A stock award may be subject to additional acceleration of vesting and exercisability upon or after a change in control as may be provided in an applicable award agreement or other written agreement, but in the absence of such provision, no such acceleration will occur.

2024 Inducement Plan

Our Board adopted our Inducement Plan in March 2024. Our Inducement Plan was adopted without stockholder approval pursuant to Rule 5635(c) of the Nasdaq Listing Rules.

Our Inducement Plan provides for the grant of NSOs, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance stock awards, performance cash awards and other forms of stock awards. Our Inducement Plan does not provide for the grant of ISOs within the meaning of Section 422 of the Code.

Stock awards granted under our Inducement Plan may only be made to individuals who did not previously serve as our employees or non-employee directors or an affiliate of us (or following such individuals’ bona fide period of non-employment with us or an affiliate of us), as an inducement material to the individuals’ entering into employment with us or an affiliate of us or in a manner otherwise permitted by the Nasdaq Listing Rules.

The terms of our Inducement Plan are otherwise substantially similar to our 2018 Plan (including with respect to the treatment of stock awards upon corporate transactions involving us or certain changes in our capitalization), except stock awards granted under our Inducement Plan may not be repriced without stockholder approval.

The maximum number of shares of our common stock that may be issued under our Inducement Plan is 1,500,000 shares. Shares subject to stock awards granted under our Inducement Plan that expire or terminate without being

exercised in full, or that are settled in cash rather than in shares, do not reduce the number of shares available for issuance under our Inducement Plan. Additionally, shares become available for future grant under our Inducement Plan if they were issued under stock awards granted under our Inducement Plan and we repurchase or reacquire them or they are forfeited. This includes shares used to pay the exercise price of a stock award or to satisfy the tax withholding obligations related to a stock award.

2018 Employee Stock Purchase Plan

Our Board adopted, and our stockholders approved, our ESPP in October 2018 and the ESPP became effective on October 11, 2018 in connection with our initial public offering. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the Code for U.S. employees.

Our Compensation Committee administers the ESPP. The ESPP is implemented through a series of offerings under which eligible employees are granted purchase rights to purchase shares of our common stock on specified dates during such offerings. Under the ESPP, we may specify offerings with durations of not more than 27 months, and may specify shorter purchase periods within each offering. Each offering will have one or more purchase dates on which shares of our common stock will be purchased for employees participating in the offering. An offering under the ESPP may be terminated under certain circumstances.

Generally, all regular employees, including executive officers, employed by us or by any of our designated affiliates, may participate in the ESPP and may contribute, normally through payroll deductions, up to 15% of their earnings (as defined in the ESPP) for the purchase of our common stock under the ESPP, subject to certain limitations set forth in the ESPP of offering document thereunder. Unless otherwise determined by our Compensation Committee or Board, common stock will be purchased for the accounts of employees participating in the ESPP at a price per share that is at least the lesser of (1) 85% of the fair market value of a share of our common stock on the first date of an offering, or (2) 85% of the fair market value of a share of our common stock on the date of purchase.

In the event of certain significant corporate transactions (as defined in the ESPP), any then-outstanding rights to purchase our stock under the ESPP may be assumed, continued, or substituted for by any surviving or acquiring entity (or its parent company). If the surviving or acquiring entity (or its parent company) elects not to assume, continue, or substitute for such purchase rights, then the participants’ accumulated payroll contributions will be used to purchase shares of our common stock within 10 business days before such corporate transaction, and such purchase rights will terminate immediately.

Our Board has the authority to amend or terminate our ESPP, provided that except in certain circumstances such amendment or termination may not materially impair any outstanding purchase rights without the holder’s consent. We will obtain stockholder approval of any amendment to our ESPP as required by applicable law or listing requirements.

Director Compensation

The following table sets forth in summary form information concerning the compensation that we paid or awarded during the year ended December 31, 2025, to each of our directors that was not also a named executive officer. Our named executive officers who are also members of our Board did not receive additional compensation for their Board service.