UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No.)

Filed by the Registrant ☒                     Filed by a Party other than the Registrant ☐

Check the appropriate box:

☐       Preliminary ProxyStatement

☐       Confidential, for Use of the Commission Only (as permitted by Rule14a-6(e)(2))

☒       Definitive ProxyStatement

☐       Definitive AdditionalMaterials

☐       Soliciting Material Under Rule14a-12

SYNLOGIC, INC.

(Name of Registrant as Specified In Its Charter)

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

Payment of Filing Fee (Check the appropriate box):

April 18, 201927, 2022

To Our Stockholders:

You are cordially invited to attend the 2019 annual meeting2022 Annual Meeting of stockholdersStockholders (“Annual Meeting”) of Synlogic, Inc. to(“Synlogic”) The meeting will be held on Thursday, June 9, 2022 at 9:00 a.m. Eastern Time on Wednesday, June 5, 2019 at 301 Binney Street, Suite 402, Cambridge, MA 02142.

Details regardingEDT. The Annual Meeting will be held in a virtual meeting format only. You can attend the meeting, the business to be conducted at the meeting, and information about Synlogic that you should consider when youAnnual Meeting online, vote your shares electronically, and submit your questions during the Annual Meeting by visiting www.virtualshareholdermeeting.com/SYBX2022and entering your 16-digit control number found on the Notice of Internet Availability or the proxy card that you receive. For further information about the Annual Meeting, please see the Information About the Annual Meeting and Voting beginning on page 3. You will not be able to attend the Annual Meeting in person.

Over the last year we have continued to make progress advancing our Synthetic Biotics to patients. Most notably, in September of last year, we delivered our first proof of concept (“PoC”) with the positive interim analysis from our phenylketonuria (“PKU”) program’s Phase 2 study. Our PKU program demonstrated clinically meaningful reductions of phenylalanine (“Phe”) in patients with PKU, in an interim analysis of the Phase 2 SynPheny-1 study, supporting the ability of Synthetic Biotic medicines to make a meaningful difference to patients.

We closed 2021 having made additional progress in multiple programs, including clinical proof of mechanism in enteric hyperoxaluria, a research collaboration with Roche in inflammatory bowel disease (“IBD”) and a new clinical candidate for homocystinuria (“HCU”) developed in partnership with Ginkgo Bioworks. We are describedbuilding on this progress in 2022 with multiple readouts expected across our programs.  

The agenda for this proxy statement.

AtAnnual Meeting includes (i) the annual meeting,election of three people will be elected(3) Class I directors, each to serve a three-year term, (ii) an advisory vote on the compensation paid to our Boardnamed executive officers, and (iii) the ratification of Directors. In addition, we will ask stockholders to ratify the selectionappointment of KPMG LLP as our independent registered public accounting firm for ourthe fiscal year ending December 31, 2019. The2022. Our Board of Directors recommends the approval of eachelection of the two proposals.three nominees to our Board of Directors and a vote in favor of proposals (ii) and (iii). Such other business will be transacted as may properly come before the annual meeting.Annual Meeting.

Under Securities and Exchange Commission rules that allow companies to furnish proxy materials to stockholders over the Internet, we have elected to deliver our proxy materials to the majority of our stockholders over the Internet. This delivery process allows us to provide stockholders with the information they need, while at the same time conserving natural resources and lowering the cost of delivery.digitally. On April 18, 2019,27, 2022, we intend to begin sending to our stockholders a Notice of Internet Availability of Proxy Materials (the “Notice”) containing instructions on how to access our proxy statement for our 2019 annual meeting2022 virtual-only Annual Meeting of stockholders and our 20192021 annual report to stockholders. The Notice also provides instructions on how to vote online or by telephone, and how to receive a paper copy of the proxy materials by mail.mail and how to access the virtual Annual Meeting.

We hope you will be able to attend the annual meeting.Annual Meeting. Whether you plan to attend the annual meetingAnnual Meeting or not, it is important that you cast your vote either in person or by proxy.vote. You may vote over the Internet as well as by telephone or by mail. When you have finished reading the proxy statement, you are urged to vote in accordance with the instructions set forth in this proxy statement. We encourage you to vote by proxy so that your shares will be represented and voted at the meeting, whether or not you can attend.meeting.

Thank you for your continued support of Synlogic.Synlogic, Inc. We look forward to seeing you joining us at the annual meeting.this year’s Annual Meeting.

Sincerely,

Aoife Brennan

President and CEO, CMO

April 18, 201927, 2022

NOTICE OF 20192022 ANNUAL MEETING OF STOCKHOLDERS

TIME: 9:00 a.m. Eastern Time

DATE: Wednesday, June 5, 2019

PLACE:

All stockholders are cordially invited to attend the virtual annual meeting.Whether you plan to attend the annual meetingAnnual Meeting or not, we urge you to vote by following the instructions in the Notice of Internet Availability of Proxy Materials that you previously received and submit your proxy by the Internet, telephone or mail in order to ensure the presence of a quorum.You may change or revoke your proxy at any time before it is voted at the meeting.

BY ORDER OF THE BOARD OF DIRECTORS

Maiken Keson-Brookes

Secretary

TABLE OF CONTENTS

i

SYNLOGIC, INC.

301 Binney Street, Suite 402

Cambridge, MA 02142

PROXY STATEMENT FOR THE 20192022 ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON JUNE 5, 20199, 2022

This proxy statement, along with the accompanying notice of 2019 annual meeting2022 Annual Meeting of stockholders, contains information about the 2019 annual meeting2022 Annual Meeting of stockholders of Synlogic, Inc., including any adjournments or postponements of the annual meeting.Annual Meeting. We are holding the annual meeting at 9:00 a.m., Eastern Time, on Wednesday,Thursday, June 5, 2019, at our corporate offices located at 301 Binney Street, Suite 402, Cambridge, MA 02142.9, 2022. You will be able to attend the annual meeting, vote and submit your questions during the meeting by visiting www.virtualshareholdermeeting.com/SYBX2022.

In this proxy statement, we refer to Synlogic, Inc. as “Synlogic,” “the Company,” “we”, and “us.”

This proxy statement relates to the solicitation of proxies by our Board of Directors, or Board, for use at the annual meeting.

On or about April 18, 2019,27, 2022, we intend to begin sending to our stockholders the Important Notice Regarding the Availability of Proxy Materials containing instructions on how to access our proxy statement for our 20192022 virtual-only annual meeting of stockholders and our 20182021 annual report to stockholders.

EXPLANATORY NOTE

On August 28, 2017, Synlogic, Inc., formerly known as Mirna Therapeutics, Inc. (NASDAQ: MIRN) (“Mirna”), completed its business combination with Synlogic, Inc. (“Private Synlogic”) in accordance with the terms of the Agreement and Plan of Merger and Reorganization, dated as of May 15, 2017, by and among Mirna, Meerkat Merger Sub, Inc. (“Merger Sub”), and Private Synlogic (the “Merger Agreement”), pursuant to which Merger Sub merged with and into Private Synlogic, with Private Synlogic surviving as a wholly owned subsidiary of Mirna (the “Merger”). On August 28, 2017, immediately after completion of the Merger, Mirna changed its name to “Synlogic, Inc.” (“Public Synlogic”) (NASDAQ: SYBX).

In this proxy statement, unless the context specifically indicates otherwise, “the Company”, “we”, “us”, “our”, and “Synlogic” refer to Public Synlogic and its subsidiaries following the Merger, effective on August 28, 2017, and to Private Synlogic and its subsidiaries prior to the Merger. References to“Pre-Merger Mirna” means Mirna prior to the Merger effective on August 28, 2017.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE

SHAREHOLDER STOCKHOLDER MEETING TO BE HELD ON JUNE 5, 20199, 2022

This proxy statement, the Notice of Annual Meeting of Stockholders, our form of proxy card and our 2018 annual report2021 Annual Report to stockholders are available for viewing, printing and downloading at www.proxyvote.com.To view these materials please have your12-digit 16-digit control number(s) available that appears on your Notice or proxy card. On this website, you can also elect to receive future distributions of our proxy statements and annual reports to stockholders by electronic delivery.

Additionally, you can find a copy of our Annual Report on Form10-K, which includes our financial statements, for the fiscal year ended December 31, 20182021 on the website of the Securities and Exchange Commission, or the SEC, atwww.sec.gov, or in the “Financials” section of the “Investors & Media” section of our website atwww.synlogictx.com. You may also obtain a printed copy of our Annual Report on Form10-K, including our financial statements, free of charge, from us by sending a written request to: Attn: Investor Relations, Synlogic, Inc., 301 Binney Street, Suite 402, Cambridge, MA 02142. Exhibits will be provided upon written request and payment of an appropriate processing fee.

shares should be voted for or withheld for each nominee for director, and whether your shares should be voted for, against or abstain with respect to the other proposal. If you properly submit a proxy without giving specific voting instructions, your shares will be voted in accordance with the Board’s recommendations as noted below. Voting by proxy will not affect your right to attend the annual meeting. If your shares are registered directly in your name through our stock transfer agent, American Stock Transfer & Trust Company, LLC, or you have stock certificates registered in your name, you may vote:

Telephone and Internet voting facilities for stockholders of record will be available 24 hours a day and will close at 11:59 p.m. Eastern Time on June 4, 2019.8, 2022.

If your shares are held in “street name” (held in the name of a bank, broker or other holder of record), you will receive instructions from the holder of record. You must follow the instructions of the holder of record in order for your shares to be voted. Telephone and Internet voting also will be offered to stockholders owning shares through certain banks and brokers. If your shares are not registered in your own name and you plan to vote your shares in person at the time of the virtual annual meeting, you should contact your broker or agent to obtain a legal proxy or broker’s proxy card and bring it tovote your shares online at the annual meeting in order to vote.time of the meeting.

How Does the Board Recommend That I Vote on the Proposals?

The Board recommends that you vote as follows:

If any other matter is presented at the annual meeting, your proxy provides that your shares will be voted by the proxy holder listed in the proxy in accordance with his or her best judgment. At the time this proxy statement was first made available, we knew of no matters that needed to be acted on at the annual meeting, other than those discussed in this proxy statement.

May I Change or Revoke My Proxy?

If you give us your proxy, you may change or revoke it at any time before the annual meeting. You may change or revoke your proxy in any one of the following ways:

Is Voting Confidential?

We will keep all the proxies, ballots and voting tabulations private. We only let our Inspector of Election, our Secretary,Elections examine these documents. Management will not know how you voted on a specific proposal unless it is necessary to meet legal requirements. We will, however, forward to management any written comments you make on the proxy card or otherwise provide.

Where Can I Find the Voting Results of the Annual Meeting?

The preliminary voting results will be announced at the annual meeting, and we will publish preliminary results, or final results if available, in a Current Report on Form8-K within four business days of the annual meeting. If final results are unavailable at the time we file the Form8-K, then we will file an amended report on Form8-K to disclose the final voting results within four business days after the final voting results are known.

What Are the Costs of Soliciting these Proxies?

We will pay all of the costs of soliciting these proxies. Our directors and employees may solicit proxies in person or by telephone, fax or email. We will pay these employees and directors no additional compensation for these services. We will ask banks, brokers and other institutions, nominees and fiduciaries to forward these proxy materials to their principals and to obtain authority to execute proxies. We will then reimburse them for their expenses.

What Constitutes a Quorum for the Annual Meeting?

The presence, in person or by proxy, of the holders of a majority of the voting power of all outstanding shares of our common stockentitledstock entitled to vote at the annual meeting is necessary to constitute a quorum at the annual meeting. Votes of stockholders of record who are present at the annual meeting in person or by proxy, abstentions, and brokernon-votes are counted for purposes of determining whether a quorum exists.

Attending the Annual Meeting

The annual meetingThis year, we will be heldhost our Annual Meeting at 9:00 a.m. Eastern timeon Wednesday,time on Thursday, June 5, 2019at 301 Binney Street, Suite 402, Cambridge, MA 02142. When you arrive, signs9, 2022. You will direct yoube able to participate in the appropriateAnnual Meeting, vote your shares electronically and submit your questions during the live webcast of the meeting rooms. by visiting www.virtualshareholdermeeting.com/SYBX2022 and entering your 16-digit control number found on the enclosed voting form. You doneed not need to attend the annual meetingAnnual Meeting in order to vote.

Householding of Annual Disclosure Documents

SEC rules concerning the delivery of annual disclosure documents allow us or your broker to send a single Notice or, if applicable, a single set of our proxy materials to any household at which two or more of our stockholders reside, if we or your broker believe that the stockholders are members of the same family. This practice, referred to as “householding,” benefits both you and us. It reduces the volume of duplicate information received at your household and helps to reduce our expenses. The rule applies to our Notices, annual reports, proxy statements and information statements. Once you receive notice from your broker or from us that communications to your address will be “householded,” the practice will continue until you are otherwise notified or until you revoke your consent to the practice. Stockholders who participate in householding will continue to have access to and utilize separate proxy voting instructions.

If your household received a single Notice or, if applicable, a single set of proxy materials this year, but you would prefer to receive your own copy, please contact our corporate secretaryCorporate Secretary at Synlogic, Inc., 301 Binney Street, Suite 402, Cambridge MA 02142.

If you do not wish to participate in “householding” and would like to receive your own Notice or, if applicable, set of Synlogic’s proxy materials in future years, follow the instructions described below. Conversely,

Conversely, if you share an address with another Synlogic stockholder and together both of you would like to receive only a single Notice or, if applicable, set of proxy materials, follow these instructions:

Electronic Delivery of Company Stockholder Communications

Most stockholders can elect to view or receive copies of future proxy materials over the Internet instead of receiving paper copies in the mail.

You can choose this option and save the Company the cost of producing and mailing these documents by:

Israel Deaconess Medical Center in Boston and is a graduate of the Harvard Medical School Scholars in Clinical Science Program. The Board has concluded that Dr. Brennan possesses specific attributes that qualify her to serve as a member of our Board, including the perspective and experience she brings as our Chief Executive OfficerPresident and Chief MedicalExecutive Officer, which brings operational expertise to our Board.

Richard P. Shea, age 67, has served as a member of our Board since the Merger closed on August 28, 2017. Mr. Shea has served as the Chief Financial Officer of Syndax Pharmaceuticals, Inc. since February 2017. Mr. Shea previously served as a member of the Syndax Pharmaceuticals board of directors from January 2014 to February 2017. From July 2007 through December 2016, Mr. Shea served as Senior Vice President and Chief Financial Officer of Momenta Pharmaceuticals Inc., a publicly-traded biotechnology company, and was its Vice President and Chief Financial Officer since October 2003. Prior to joining Momenta, Mr. Shea served as Chief Operating Officer and Chief Financial Officer of Variagenics Inc., a publicly-traded pharmacogenomics company, that was merged with Hyseq Pharmaceuticals Inc., and as Vice President, Finance of Genetics Institute, Inc., a publicly-traded biotechnology company, which was acquired by Wyeth Pharmaceuticals, Inc., which was then acquired by Pfizer, Inc. Mr. Shea received an A.B. from Princeton University and an M.B.A. from the Public Management Program at Boston University. The Board has concluded Mr. Shea possesses specific attributes that qualify him to serve as a member of our Board, including his experience with the healthcare and pharmaceutical industries and his broad life sciences industry knowledge.

Patricia Hurter, Ph.D., age 55, has served as a member of Synlogic’s Board since February 2019. Dr. Hurter has been Senior Vice President at Vertex since 2011, during which time her responsibilities grew to include all CMC and preclinical development activities of Vertex’s R&D portfolio, as well as the internal GMP manufacturing facility that provides drug substance and product for clinical development and commercial supply. From 2013 to 2014, she served as Interim Head of Global Regulatory Affairs at Vertex and oversaw the submission of the new drug application for Orkambi^®, as well as several label expansions for Kalydeco^®. She has played a leadership role in the development and commercialization of four transformative therapies for Vertex: Incivek^®, Kalydeco^®, Orkambi^® and Symdeko^®. Prior to joining Vertex, Dr. Hurter was Director, Formulation Design and Characterization for Merck where she was a key member of the early development team for Januvia^®, a treatment for Type II diabetes. Dr. Hurter serves as a member of the Board of Trustees of Harvard Conservation Trust. She holds a Ph.D. in chemical engineering from the Massachusetts Institute of Technology, an M.S. in mechanical engineering from West Virginia University and earned a B.Sc. in chemical engineering,cum laude, from the University of KwaZulu-Natal in Durban, South Africa. The Board has concluded that Dr. Hurter possesses specific attributes that qualify her to serve as a member of our Board, including her experience in drug research and development, global regulatory affairs and GMP manufacturing.

Peter Barrett, Ph.D., age 66,69, has served as Chairman of our Board since the Merger (defined below) closed on August 28, 2017, and prior to that time served as the Chairman of the Private Synlogic (defined below) board of directors since March 2014. Dr. Barrett joinedis a partner at Atlas Venture L.P., an early-stage venture capital fund,and has been involved in 2002,the creation of several novel therapeutic and drug discovery platform companies. He is also a Senior Fellow at Harvard Business School, where he is the Faculty Chair of the Key Advisory Board of the Blavatnik Fellowship Program. Dr. Barrett currently serves as a Partner. From 1998on the board of Larimar Therapeutics and Obsidian Therapeutics. Prior to 2002,joining Atlas, Dr. Barrett was Co-founder, Executive Vice Presidentpresident, and Chief Business Officer of Celera Genomics, Group (nowwhich announced the first successful sequencing of the human genome in 2001. While at Celera, Corporation,Dr. Barrett led strategic alliances, acquisitions, and business strategy and helped launch it as a subsidiary of Quest Diagnostics), a biotechnologypublic company whichhe co-founded. From 1979in 1999. Prior to 1998,founding Celera, Dr. Barrett held senior management positions at Perkin-Elmer Corporation,Applera, most recently serving as Vice President Corporate Planningof corporate planning and Business Development.business development. During his tenure, he ran several businesses and expanded the life science business through a series of licensing agreements, partnerships, and acquisitions. Dr. Barrett currentlyalso serves on the boards of directors of PerkinElmer, Inc., Zafgen, Inc. and several privately held companies. Dr. Barrett is a Senior Fellow at Harvard Business School and is the faculty chair of the key advisory board of the Blavatnik Fellowship Program.Perkin-Elmer Corporation. Dr. Barrett isreceived a member of the research council at Boston Children’s Hospital. Dr. Barrett holds a B.S.BS in Chemistrychemistry from Lowell Technological Institute (now known as the University of Massachusetts, Lowell), and a Ph.D. in Analytical Chemistryanalytical chemistry from Northeastern University. He also

9

completed Harvard Business School’s Management Development Program. The Board has concluded that Dr. Barrett possesses specific attributes that qualify him to serve as a member and chairman of the Board, including his extensive leadership, executive, managerial and business experience with life sciences companies, including experience in the formation, development and business strategy of multiplestart-up companies in the life sciences sector.

Edward MathersMichael Burgess, M.B., Ch.B., Ph.D., age 59, has served as a member of our Board since January 2020. Dr. Burgess joined SpringWorks Therapeutics, a clinical-stage biopharmaceutical company that applies a precision medicine approach to acquiring, developing and commercializing life-changing medicines, in May 2021 as Head of Research and Development. Dr. Burgess currently serves on the board of directors at Turnstone Biologics, a clinical stage viral immunotherapy cancer company, and previously served as President of Research and Development at Turnstone Biologics, since October 2017, where he led the build out of the cancer immunotherapy R&D organization. Prior to Turnstone, Dr. Burgess led strategy and execution of translational medicine, early-stage clinical trials and clinical pharmacology across all therapeutic areas, including oncology at Bristol-Myers Squibb from January 2013 to September 2017. Prior to this, at Roche Pharmaceuticals, he held several senior leadership positions, including acting global head of Roche Pharma Research and Early Development (pRED) and Senior Vice President and Global Head of Oncology Research and Early Development. Before joining Roche, Dr. Burgess spent 7 years at Eli Lilly and Company working on early stage oncology trials. Dr. Burgess received his medical degree (M.B., Ch.B.) and a Ph.D. in molecular biology from the University of Bristol, UK and spent 10 years as a practicing physician in pediatrics and pediatric oncology. The Board has concluded that Dr. Burgess possesses specific attributes that qualify him to serve as a member of our Board, including his experience in the pharmaceutical industry and drug research and development.

Michael Heffernan, age 57, has served as a member of or Board since December 2020. Mr. Heffernan is a successful entrepreneur and biopharmaceutical leader with over 30 years of experience in building and leading development stage and commercial companies. He is the Founder and Chairman of Collegium Pharmaceutical, a publicly traded pharmaceutical company that he founded that is focused on developing and commercializing products for the treatment of chronic pain and related disorders. He served as its President and CEO from company inception until June 2018. Mr. Heffernan is currently an advisor, investor and board member in numerous public and private biotech companies. He recently co-founded Avenge Bio, Inc., an immuno-oncology company that he is actively managing and serves as the Chairman and CEO. Mr. Heffernan has held previous positions as CEO of Onset Dermatologics, a dermatology company that he founded and spun out of Collegium to create PreCision Dermatology which was sold to Valeant. He was co-founder and CEO of Clinical Studies Ltd., a pharmaceutical contract research organization that was sold to PhyMatrix Corp, a public healthcare services company, where he later served as CEO and Chairman. Mr. Heffernan began his career at Eli Lilly and Company and served in numerous sales and marketing roles. In addition to Collegium, Mr. Heffernan is currently on the board of directors of Akebia Therapeutics, Inc., Trevi Therapeutics, Inc., Biohaven Pharmaceuticals where he also serves as Chairman. He has served in a number of non-profit roles as both an advisor and board member. Mr. Heffernan was named E&Y Entrepreneur of the Year, Northeast Regional Winner in 2016. He is a registered pharmacist and earned his B.S. Degree in Pharmacy from the University of Connecticut. The Board has concluded that Mr. Heffernan possesses specific attributes that qualify him to serve as a member our Board, including his experience with the healthcare and pharmaceutical industries and his broad management experience.

Patricia Hurter, Ph.D., age 58, has served as a member of our Board since February 2019. Since September 2019, Dr. Hurter has served as CEO of Lyndra Therapeutics. Lyndra is a clinical-stage biopharmaceutical company pioneering long-acting oral therapies with a pipeline focused on therapies in central nervous system (CNS) disorders. Prior to Lyndra, Dr. Hurter was Senior Vice President of Pharmaceutical and Preclinical Sciences at Vertex Pharmaceuticals, Inc. from June 2014 to April 2019. She also served as Interim Head of Global Regulatory Affairs from 2013-2014 and oversaw several label expansions for Kalydeco® and the submission of the new drug application for Orkambi®. She played a leadership role in the development and commercialization of 5 transformative therapies for Vertex: Incivek®, Kalydeco®, Orkambi®, Symdeko® and Trikafta®. Prior to joining Vertex, Dr. Hurter was Director, Formulation Design and Characterization for Merck where she was a key member of the early development team for Januvia®, a treatment for Type II diabetes. A respected thought leader in the pharmaceutical industry, Dr. Hurter is a frequent contributor to many scientific publications. At Vertex, she founded and was the executive sponsor of “IWILL,” a Vertex employee network devoted to the advancement of women leaders. She holds a Ph.D. in chemical engineering from the Massachusetts Institute of Technology, an M.S. in mechanical engineering from West Virginia University and earned a B.Sc. in chemical engineering, cum laude, from the University of KwaZulu-Natal in Durban, South Africa. She was elected to the National Academy of Engineering in 2021. The Board has concluded that Dr. Hurter possesses specific attributes that qualify her to serve as a member of our Board, including her experience in drug research and development, global regulatory affairs and GMP manufacturing.

Lisa Kelly-Croswell, age 55, has served as a member of our Board since February 2021. Ms. Kelly-Croswell serves as Senior Vice President and Chief Human Resources Officer for Boston Medical Center Health System (BMCHS), an academic medical center including a health plan as well as biomedical and clinical research portfolios. Prior to BMCHS, Ms. Kelly-Croswell was Senior Vice President, Human Resources at Vertex Pharmaceuticals, from July 2006 to June 2013, where she was part of the executive team evolving the company from an early stage biotech to a fully commercialized pharmaceutical company.  Prior to Vertex, she served in senior leadership positions at Nitromed, CIGNA, and Monsanto Company. Ms. Kelly-Croswell began her career in a series of progressive HR positions at Frito-Lay, Inc. with a deeper focus in manufacturing. Ms. Kelly-Croswell received a B.S., Finance and M.A., Labor and Industrial Relations from the University of Illinois at Urbana-Champaign and is a current and past board member for multiple non-profit boards of directors. The Board has concluded that Ms. Kelly Croswell possesses specific attributes that qualify her to serve as a member of our Board, including her experience as a global human resources executive, and involvement in rapid business growth environments and innovative organizations.

Nick Leschly, age 49, has served as a member of our Board since the Merger (defined below) closed on August 28, 2017, and prior to that time served on the Private Synlogic (defined below) board of directors since March 2016. Mr. Leschly is the chief executive officer at 2Seventy Bio. Prior to that, he served as the chief bluebird of bluebird bio, Inc., a publicly-traded clinical-stage biotechnology company, since September 2010.  Formerly a founding partner of Third Rock Ventures, L.P. since 2007, Mr. Leschly played an integral role in the overall formation, development and business strategy of several of Third Rock’s portfolio companies, including Agios Pharmaceuticals. Prior to joining Third Rock, he worked at

10

Millennium Pharmaceuticals, Inc. (now a subsidiary of Takeda), leading several early-stage drug development programs and served as the product and alliance leader for VELCADE®.  He received his B.S. in Molecular Biology from Princeton University and his M.B.A. from Wharton Business School. He also serves on the advisory boards for Princeton University Molecular Biology Department and the Special Olympics of Massachusetts. The Board has concluded that Mr. Leschly possesses specific attributes that qualify him to serve as a member of our Board, including his experience in the venture capital industry and drug research and development.

Edward Mathers, age 62, has served as a member of our Board since October 2012. Mr. Mathers previously served on the Private Synlogic (defined below) board of directors since July 2014.  Since 2008, Mr. Mathers has beenis a General Partner at NEA, a private venture capital firm focusing on technology and healthcare investments. Mr. Mathers serves on the board of directors of the following publicly-traded pharmaceutical companies: ObsEva SA, RaTrevi Therapeutics, Akouos, Inc, Inozyme Pharma, Mirum Pharmaceuticals, Rhythm Pharmaceuticals, Inc., and RhythmReneo Pharmaceuticals, Inc. Mr. Mathers also serves on the board of directors of several privately held companies. From 2002 to 2008, Mr. Mathers served as Executive Vice President, Corporate Development and Venture at MedImmune, Inc., a biopharmaceutical company, and led its venture capital subsidiary, MedImmune Ventures, Inc. Before joining MedImmune in 2002, Mr. Mathers was Vice President, Marketing and Corporate Licensing and Acquisitions at Inhale Therapeutic Systems, a biotechnology company. Previously, Mr. Mathers spent 15 years at Glaxo Wellcome, Inc. (GlaxoSmithKline), a pharmaceutical company, where he held various sales and marketing positions. Mr. Mathers received a B.S. in Chemistry from North Carolina State University. The Board has concluded that Mr. Mathers possesses specific attributes that qualify him to serve as a member our Board, including his experience with the healthcare and pharmaceutical industries and his broad management experience.

Michael Powell, Ph.D.,

Richard P. Shea, age 64,70, has served as a member of our Board since October 2012. Dr. Powell previously served as Chairman of our Board from October 2012 until the Merger (defined below) closed on August 28, 2017. Since 1997, Dr. Powell has beenMr. Shea served as the Chief Financial Officer of Syndax Pharmaceuticals, Inc. from February 2017 through July 2020. Mr. Shea previously served as a General Partnermember of Sofinnova Ventures, a venture capital firm. Previously, Dr. Powell has held positions at Genentech,the Syndax Pharmaceuticals board of directors from January 2014 to February 2017. From July 2007 through December 2016, Mr. Shea served as Senior Vice President and Chief Financial Officer of Momenta Pharmaceuticals Inc., a publicly traded biotechnology company, Cyteland was its Vice President and Chief Financial Officer since October 2003. Prior to joining Momenta, Mr. Shea served as Chief Operating Officer and Chief Financial Officer of Variagenics Inc., a researchpublicly traded pharmacogenomics company, that was merged with Hyseq Pharmaceuticals Inc., and developmentas Vice President, Finance of Genetics Institute, Inc., a publicly traded biotechnology company, which was acquired by Wyeth Pharmaceuticals, Inc., which was then acquired by Pfizer, Inc. Mr. Shea received an A.B. from Princeton University and Syntex Research Group, a pharmaceutical company. Dr. Powell currently serves on the board of directors of numerous privately-held companies. Dr. Powell is an Adjunct Professor at the University of Kansas. Dr. Powell is the Board President of the AIDS Vaccine Advocacy Coalition and serves on the advisory board of the Institute for the Advancement of Medical Innovation at the University of Kansas. Dr. Powell received a B.S. in Chemistry from Scarborough College, a Ph.D. in Physical ChemistryM.B.A. from the University of Toronto and completed his post-doctoral work in Bioorganic ChemistryPublic Management Program at the University of California.Boston University. The Board has concluded that Dr. PowellMr. Shea possesses specific attributes that qualify him to serve as a member of our Board, including his experience with the life scienceshealthcare and pharmaceutical industries and the venture capital industry.

Chau Khuong, age 43, has served as a member of our Board since the Merger closed on August 28, 2017, and prior to that time served on the Private Synlogic board of directors since February 2016. Mr. Khuong has worked at OrbiMed Advisors LLC, a private equity and venture capital firm, since 2003 and is Private Equity Partner. Mr. Khuong gained experiencein start-up operations and business development at Veritas Medicine, Inc., a healthcare company, and in basic science research at the Yale School of Medicine and Massachusetts General Hospital. Mr. Khuong currently serves as a director of the following publicly-traded companies: Aerpio Pharmaceuticals, Inc. and Pieris Pharmaceuticals, Inc. Mr. Khuong also serves on the board of directors of several privately held companies. Mr. Khuong holds a B.S. in Molecular, Cellular and Developmental Biology with concentration in Biotechnology and an M.P.H. with concentration in Infectious Diseases, both from Yale University. The Board has concluded that Mr. Khuong possesses specific attributes that qualify him to serve as a member of our Board, including his experience as an investor, particularly with respect to healthcare companies, and his broad life sciences industry knowledge. Mr. Khuong also has extensive experience overseeing the operations and research and development of biotechnology companies.

Nick Leschly, age 46, has served as a member of our Board since the Merger closed on August 28, 2017, and prior to that time served on the Private Synlogic board of directors since March 2016. Mr. Leschly has served as the President and Chief Executive Officer of bluebird bio, Inc. (“bluebird bio”), a publicly-traded clinical-stage biotechnology company, since September 2010. Previously, he served as the Interim Chief Executive Officer of bluebird bio from March 2010 to September 2010. Formerly a partner of Third Rock Ventures, L.P. (“Third Rock”) since its founding in 2007, Mr. Leschly played an integral role in the overall formation, development and business strategy of several of Third Rock’s portfolio companies, including Agios Pharmaceuticals, Inc. and Edimer Pharmaceuticals, Inc. Prior to joining Third Rock, he worked at Millennium Pharmaceuticals, Inc. (now a subsidiary of Takeda), leading several early-stage drug development programs and served as the product and

alliance leader for VELCADE^®. Mr. Leschly also founded and served as Chief Executive Officer of MedXtend Corporation. He received his B.S. in Molecular Biology from Princeton University and his M.B.A. from Wharton Business School. He serves on the board of Biotechnology Innovation Organization (BIO) and Proclara Biosciences. He also serves on the advisory boards for Princeton University Molecular Biology Department and the Special Olympics of Massachusetts. The Board has concluded that Mr. Leschly possesses specific attributes that qualify him to serve as a member of our Board, including his experience in the venture capital industry and drug research and development.

Committees of the Board of Directors and Meetings

Meeting Attendance.During the fiscal year ended December 31, 2018,2021, Synlogic’s Board held four meetings, and the various committees of the Board met a total of twelvefifteen times. All directors attended at least 75% of the total number of meetings of the Board and of committees of the Board on which he or she served during fiscal 2018.2021. Synlogic’s annual meeting was held on June 13, 20189, 2021 and fiveall of Synlogic’s sixnine directors attended the meeting. We encourage our directors to attend the annual meeting.Annual Meeting.

Audit Committee.Synlogic’s Audit Committee met seveneight times during fiscal 2018.2021. This committee currently has threefour members, Richard P. Shea (Chairman), Peter Barrett, Michael Burgess and Michael Powell.Heffernan. Our Audit Committee’s role and responsibilities are set forth in the Audit Committee’s written charter and include the authority to retain and terminate the services of our independent registered public accounting firm. In addition, the Audit Committee reviews annual financial statements, considers matters relating to accounting policy and internal controls and reviews the scope of annual audits. All members of the Audit Committee satisfy the current independence standards promulgated by the Securities and Exchange Commission and by the Nasdaq Stock Market, as such standards apply specifically to members of audit committees. The Board has determined that Mr. Barrett is independent even though he falls outside the “safe harbor” definition set forth in Rule10A-3(e)(1)(ii) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”) because Atlas Venture L.P. and its affiliates own in excess of 10% of our common stock. Among other things, the Board considered Mr. Barrett’s history of service and the percentage of common stock held by others, and it determined that he is not an “affiliated person” of our company who would be ineligible to serve on the Audit Committee. The Board has determined that Mr. Shea is an “audit committee financial expert,” as the Securities and Exchange Commission has defined that term in Item 407 of RegulationS-K. Please also see the report of the Audit Committee set forth elsewhere in this proxy statement.

A copy of the Audit Committee’s written charter is publicly available on our website atwww.synlogictx.com.

Compensation Committee.Synlogic’s Compensation Committee met three times during fiscal 2018.2021. This committee currently has three members, Edward Mathers (Chairman)Lisa Kelly-Croswell (Chair), Chau KhuongNick Leschly and Nick Leschly.Ed Mathers. Our Compensation Committee’s role and responsibilities are set forth in the Compensation Committee’s written charter and includes reviewing, approving and making recommendations regarding our compensation policies, practices and procedures to ensure that legal and fiduciary responsibilities of the Board are carried out and that such policies, practices and procedures contribute to our success. Our Compensation Committee also administers our 2015 Equity Incentive Award Plan, and 2017 Stock Incentive Plan, and 2015 Employee Stock Purchase Plan. The Compensation Committee reviews and recommends policies relating to compensation and benefits of our officers and employees. The Compensation Committee reviews and recommends corporate goals and objectives relevant to compensation of our Chief Executive Officer and other executive officers, evaluates the performance of these officers in light of those goals and objectives and may approve the compensation of the executive officers, other than the Chief Executive Officer, whose compensation the Compensation Committee recommends to the Board, based on such evaluations. The Compensation Committee also recommends to the Board the issuance of stock options and other awards under our stock plans. The Board has delegated authority to our Chief Executive Officer to grant options to new hire employees as well as certain other employees in connection with their promotion who (i) are not then subject or who are reasonably expected to become subject to Section 16 of the Exchange Act, or (iii)(ii) persons

then or who are reasonably expected to be “covered employees” for purposes of Section 162(m) of the Internal Revenue Code of 1986, as amended. The purpose of this delegation of authority is to enhance the flexibility of option administration within the Company and to facilitate the timely grant of options within specified limits approved by the Board. All members of the Compensation Committee qualify as independent under the definition promulgated by the Nasdaq Stock Market.

11

The Compensation Committee has the authority to directly retain the services of independent consultants and other experts to assist in fulfilling its responsibilities. The Compensation Committee has engaged the services of Radford, a business unit of Aon plc (“Radford”), a national executive compensation consulting firm, to review and provide recommendations concerning all of the components of the Company’s executive compensation program. Radford performs services solely on behalf of the Compensation Committee and has no relationship with the Company or management except as it may relate to performing such services. Radford assists the Committee in defining the appropriate market of the Company’s peer companies for executive compensation and practices and in benchmarking our executive compensation program against the peer group each year. Radford also assists the Committee in benchmarking our director compensation program and practices against those of our peers. In compliance with the SEC and the corporate governance rules of the Nasdaq Stock Market, Radford provided the Compensation Committee with a letter addressing each of the six independence factors. Their responses affirm the independence of Radford and the partners, consultants, and employees who service the Compensation Committee on executive compensation matters and governance issues.

A copy of the Compensation Committee’s written charter is publicly available on our website atwww.synlogictx.com.

Nominating and Governance Committee.Synlogic’s Nominating and Governance Committee met twofour times during fiscal 2018.2021. This committee currently has three members, Michael PowellHeffernan (Chairman), Peter BarrettLisa Kelly-Croswell and Patricia Hurter. Our Board has determined that all members of the Nominating and Governance Committee qualify as independent under the definition promulgated by the Nasdaq Stock Market. The Nominating and Governance Committee’s responsibilities are set forth in the Nominating and Governance Committee’s written charter and include:

Generally, our Nominating and Governance Committee considers candidates recommended by stockholders as well as from other sources such as other directors or officers, third party search firms or other appropriate sources. Once identified, the Nominating and Governance Committee will evaluate a candidate’s qualifications in accordance with our Corporate Governance Guidelines. Threshold criteria include: personal and professional integrity, ethics and values; absence of conflict of interest; fair and equal representation of all stockholders; commitment to promoting long term value of the company; experience in corporate management, such as serving as an officer or former officer

of a publicly held company; strong finance experience; experience relevant to the Company’s industry; experience as a board member or executive officer of another publicly held company; diversity of expertise and experience in substantive matters pertaining to the Company’s business relative to other members of the Board; diversity of background and perspective, including with respect to age, gender, race, place of residence and specialized business or career experience relevant to the success of the Company; practical and mature business judgment, including the ability to make independent analytical inquiries; and any other relevant qualifications, attributes or skills. Our Nominating and Governance Committee has not adopted a formal diversity policy in connection with the consideration of director nominations or the selection of nominees. However, the Nominating and Governance Committee will consider issues of diversity among its members in identifying and considering nominees for director and strive where appropriate to achieve a diverse balance of backgrounds, perspectives, business and career experience on the Board and its committees.

If a stockholder wishes to propose a candidate for consideration as a nominee for election to the Board, it must follow the procedures described in our bylaws, the “Policy on Stockholder Recommendation of Candidates for Election as Directors” set forth as Appendix B of the Committee Charter, and in “Stockholder Proposals and Nominations for Director” at the end of this proxy statement. In general, persons recommended by stockholders will be considered in accordance with our Corporate Governance Guidelines. Any such recommendation should be made in writing to the Nominating and Governance Committee, care of our Secretary at our principal office and should be accompanied by the following information concerning each recommending stockholder and the beneficial owner,if any, on whose behalf the nomination is made:

The recommendation must also be accompanied by the following information concerning the proposed nominee:

12

A copy of the Nominating and Governance Committee’s written charter including its appendices, is publicly available on the Company’s website atwww.synlogictx.com.

Board Leadership Structure and Role in Risk Oversight

Leadership Structure of the Board

Our Board has separated the positions of Chairman of the Board and Chief Executive Officer. Separating these positions allows our Chief Executive Officer to focus onour day-to-day business, while allowing the Chairman of our Board to lead the Board in its fundamental role of providing advice to and independent oversight of management. Our Board recognizes the time, effort and energy that the Chief Executive Officer is required to devote to such position in the current business environment, as well as the commitment required to serve as Chairman of our Board, particularly as the Board’s oversight responsibilities continue to grow. While our bylaws and corporate governance guidelines do not require that the Chairman and Chief Executive Officer positions be separate, our Board believes that having separate positions and having an independent outside director serve as Chairman is the appropriate leadership structure for us and demonstrates our commitment to good corporate governance. However, ourcurrently. Our Board will continue to periodically review our leadership structure and may make such changes in the future as it deems appropriate.

Role of Board in Risk Oversight Process

Risk assessment and oversight are an integral part of our governance and management processes. Our Board encourages management to promote a culture that incorporates risk management into our corporate strategyand day-to-day business operations. Management discusses strategic and operational risks at regular management meetings and conducts specific strategic planning and review sessions during the year that include a focused discussion and analysis of the risks facing us. Throughout the year, senior management reviews these risks with our Board at regular Board meetings as part of management presentations that focus on particular business functions, operations or strategies, and presents the steps taken by management to mitigate or eliminate such risks.

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 the Board that address risks inherent in their respective areas of oversight. In particular, our Board is responsible for monitoring and assessing strategic risk exposure and the Audit Committee is responsible for overseeing our major financial risk exposures, information technology, cybersecurity and other risks, and the steps management has taken to monitor and control these exposures. The Audit Committee also monitors compliance with legal and regulatory requirements and considers and approves or disapproves any related-persons transactions. Our Nominating and Governance Committee monitors the effectiveness of our corporate governance. The Compensation Committee assesses and monitors whether any of our compensation policies and programs has the potential to encourage excessive risk-taking.

Corporate Responsibility

We are committed to developing transformative medicines for patients in a socially responsible and sustainable manner.

Environmental Awareness:  We lease our office and manufacturing facilities. Nevertheless, we recognize the importance of taking other measures to reduce our environmental footprint. Some of our efforts include our commitment to reduce, reuse or recycle where possible or appropriate.

Social and Human Capital: At Synlogic, we believe in fostering diversity, equity and inclusion (DEI) as it is critical to our success. Strengthening our diversity is an expression of our values and imperative for our business. We believe our science has the potential to deliver transformative benefit to patients, and we are committed to bringing innovation forward by embracing the diversity of our team and the patients we serve, and by ensuring all of our community has access to opportunities and innovative therapies.

We are committed to creating a diverse and inclusive environment, embracing individuality in all forms including ability, age, color, ethnicity, family or marital status, gender identity or expression, genetics, language, national origin, political affiliation, race, religion, sexual orientation, socio-economic status, veteran status, and any other individual differences or characteristics, education, skill sets and experience. We are focused on inclusive hiring practices, fair and equitable treatment, organizational flexibility and training and resources.

We recognize that our employees are essential to our success. To this end, we support business growth by seeking to attract and retain best-in-class talent. We use internal and external resources to recruit highly skilled candidates for open positions. We believe that we are able to attract and retain the talent that is required to meet our business goals. In addition to full-time hiring, we currently partner with three separate organizations focused on under-represented and underserved communities to provide internship opportunities.

While we strive to provide real-time recognition of employee performance, we have a formal annual review process not only to determine pay and equity adjustments tied to individual contributions, but to identify areas where employees may benefit from additional training and development opportunities.

We believe in encouraging employees to be lifelong learners by providing ongoing learning and leadership training opportunities which helps us to promote key talent from within. We have partnered with the Commonwealth Corporation and a leading external training provider to provide a broad training curriculum of professional skills to all employees.  

Our total rewards philosophy has been to invest in our workforce by offering a competitive compensation and benefits package. We provide employees with compensation packages that include base salary, annual incentive bonuses and long-term equity incentive awards. Our equity incentive awards ensure alignment between our employees and shareholders and encourage an ownership mentality. We also recognize success through an ongoing peer-to-peer and manager-led recognition program, and annual awards aligned to our goals and values.  

We also offer comprehensive employee benefits, such as life, disability and health insurance, health savings and flexible spending accounts, paid time off, a 401(k) plan with market-competitive company matching contributions, and an Employee Stock Purchase Plan (ESPP). It is our express intent to be an employer of choice in our industry by providing a market-competitive compensation and benefits package.

We also conduct employee engagement surveys on a regular basis to help us understand employee satisfaction and how best to improve as an organization. Our Social Committee, consisting of employees from various functions, is dedicated to organizing activities, such as themed social gatherings, volunteer opportunities, and other events that enrich our culture and bring employees together. We also encourage employees to take one paid day off a calendar year to volunteer for the organization of their choice.

We also have an Equity, Diversity, and Inclusion Committee, comprised of employees at various levels of our organization, focused on increasing the inclusive culture of the company, and diversity of our workforce.  As of December 31, 2021, women comprise 48% of our workforce, and 50% of our Executive Team including our CEO.  Our employees are 28% BIPOC (Black, Indigenous, and people of color), with a focus on ensuring our candidate pools, and thus hires, appropriately represents our communities and the patients we serve. 

We have always invested, and will continue to invest, in the health, safety, and wellness of our employees. We provide our employees with access to a variety of innovative, flexible, and convenient health and wellness programs. Program benefits are intended to provide protection and security, so employees can have peace of mind concerning events that may require time away from work or that may impact their financial well-being. We provide an Employee Assistance Program (“EAP”) which provides consultation, referrals and resources to help employees and their household manage everyday life and work challenges. We also reimburse for fitness and other similar programs, as well as offer periodic health challenges to encourage health and well-being.

We have occupational health and safety measures that apply to all our employees, contractors and visitors. We have convened a cross-functional Safety Committee to identity and address concerns and look for areas to improve. We train individuals commensurate with their level of risk and employees are required to report incidents and are encouraged to voice any health or safety concerns to management or a Safety team member.

Our investments and the prioritization of employee health, safety, and wellness have taken on particular significance in light of the COVID-19 pandemic. To protect and support our team members, we have created a cross-functional COVID response team and implemented health and safety measures that include maximizing personal workspaces, altering work schedules, mandating vaccines, and providing asymptomatic COVID-19 testing regularly for employees who work on site. To aid in containing the spread of COVID-19, we have implemented remote-work options and have at times limited employee travel.

We are committed to the community and we and our employees participate in multiple charitable endeavors each year.  We partner with external non-profits, such as Life Science Cares, to provide further opportunities to engage with our local community. We also regularly engage directly with patients to better understand the lives of people living with rare disease which we believe can help us discover and develop potential therapies, design and execute our clinical trials, and enrich our culture. We benefit from periodic company-wide patient speaking events to ensure all our employees understand the challenges faced by the patients we serve.

Governance, Ethics, and Compliance: Our Board is committed to corporate governance, risk oversight, and ethics and compliance. Our Board has adopted Corporate Governance Guidelines, which present a framework for good corporate governance practices. The Board has also adopted a Code of Conduct and Business Ethics for all directors, officers and employees as well as a Whistleblower Policy applicable to its employees that provides for protection from retaliation due to reporting issues relating to compliance with applicable laws and regulations. We also provide for continuing education for Directors, a separate CEO and Chair Role, full independence among standing members of audit, compensation and nominating and corporate governance committees, and regular Board and Committee self-evaluation.

14

We will continue to evolve and strengthen our corporate responsibility efforts and anticipate reporting on other measures over time.

Policy Prohibiting Hedging and Pledging

Pursuant to our Insider Trading Policy, our officers, directors, employees and consultants are prohibited from engaging in transactions in publicly traded options, such as puts and calls, and other derivative securities with respect to our common stock at any time. This prohibition extends to any hedging, pledging or similar transaction designed to decrease the risks associated with holding our securities.

Stockholder Communications to the Board

Generally, stockholders who have questions or concerns should contact our Investor Relations department at (617) 639 9122.401-9975. However, any stockholders who wish to address questions regarding our business directly with the Board, or any individual director, should direct his or her questions in writing to the Chairman of the Board at Synlogic, Inc., 301 Binney Street, Suite 402, Cambridge MA 02142. Communications will be distributed to the Board, or to any individual director or directors as appropriate, depending on the facts and circumstances outlined in the communications. Items that are unrelated to the duties and responsibilities of the Board may be excluded, such as:

In addition, any material that is unduly hostile, threatening, or illegal in nature may be excluded, provided that any communication that is filtered out will be made available to any outside director upon request.

Executive Officers

The following table sets forth certain information regarding our executive officers who are not also directors.directors as of April 1, 2022. We have employment or consulting agreements with each of our executive officers.

Todd Shegog,

Antoine (Tony) Awad, age 54,42, joined Synlogic as a consultant in October 2018 and became a full-time employee in December 2018 as Head of Technical Operations and has served as Synlogic’s Chief Operating Officer since July 2020.  He is responsible for process sciences and manufacturing functions for the Company, as well as operations, information technology and facilities. Mr. Awad has over 18 years of experience in the biotechnology and pharmaceutical industry with substantial and notable experience in the development and manufacturing of multiple modalities of novel therapeutics from pre-IND studies through global commercialization. Mr. Awad resides as an advisor to the board of directors and executive team of Verseau, the macrophage company.  Prior to joining Synlogic, Mr. Awad was most recently at Abpro Therapeutics and served as Senior Vice President of CMC and Operations, from October 2017 to October 2018, where he was responsible for the development of bi-specific antibodies for oncology focused therapeutics while leading corporate operational functions, including HR, IT and facilities. Prior to that, from March 2017 to May 2017, he served as Senior Vice President of Technical Operations and Manufacturing at L.E.A.F. Pharmaceuticals focused on developing small molecules and nanotechonology based drugs for solid tumors. Previously, Mr. Awad held positions of increasing responsibilities over a ten-year period at Merrimack Pharmaceuticals, from August 2007 to March 2017. As Head of Process Sciences & Manufacturing, Mr. Awad led CMC development, manufacturing and approval of ONIVYDE® for treatment of advanced pancreatic cancer and transitioned to Ipsen Bioscience to integrate and lead commercial manufacturing of ONIVYDE®. Mr. Awad has broad experience in partnerships, collaboration and M&A, most notably with Sanofi, Baxalta/Shire plc, Actavis Pharma/Teva Pharmaceutical Industries and Ipsen Bioscience. Mr. Awad is a graduate of Boston University and holds degree in biochemistry and molecular biology and conducted graduate research at Boston University School of Dental Medicine.

Michael Jensen, age 46, joined Synlogic in September 2016March 2022 as our Chief Financial Officer, and is responsible for the oversight and direction of ourfinance, tax, accounting, treasury, and investor relations. He brings with him two decades of experience in finance and accounting leadership roles within the life science industry, ranging from venture-backed start-ups to global publicly traded pharmaceutical and medical device companies. Prior to joining Synlogic, from March 2020 to March 2022, Mr. Jensen was the CFO at Intrinsic Therapeutics, a commercial-stage medical device company focused on delivering treatments to improve surgical efficacy. Prior to Intrinsic Therapeutics, from March 2019 to March 2020, Mr. Jensen was the CFO at Taconic Biosciences. Prior to Taconic Biosciences, Mr. Jensen was the CFO at IWP, from December 2016 to February 2019. Mr. Jensen has held financial strategyleadership roles at several biotech and management as well as facilitieshealthcare companies including Straumann North America, Siemens Healthcare Diagnostics, Novartis, and information systems. From April 2014 to August 2016,Novo Nordisk Inc.  Mr. ShegogJensen holds a Master of Economics and Business Administration degree from Copenhagen Business School in Copenhagen, Denmark, and a Bachelor of Business Administration degree from Towson University in Baltimore, MD. Mr. Jensen also served as senior vice president and chief financial officer at Forum Pharmaceuticals Inc., a pharmaceutical company, where he was responsible for finance, operations and information systemsan Officer in support of the pursuit of innovative therapies for schizophrenia and Alzheimer’s disease. From 1998 to March 2014, Mr. Shegog worked in a variety of roles at Millennium Pharmaceuticals, including as Senior Vice President and Chief Financial Officer from 2008 to 2014, where he was responsible for management of Millennium’s financial resources, corporate planning, financial reporting and compliance. During his tenure at Millennium Pharmaceuticals, Mr. Shegog held key leadership roles supporting the early evolution of Millennium and its transformation from a genomics company to a fully-integrated drug developer, the approval and launch of its flagship oncology product, VELCADE^®, and the $8.8 billion acquisition of Millennium Pharmaceuticals by Takeda Pharmaceutical Co Ltd. Mr. Shegog began his career in healthcare at Genetics Institute, Inc. (now Pfizer), a biotechnology research and development company, in a variety of financial positions supporting its research and development organizations and was a member of the commercial operations team that supported the launch of BeneFIX^®. Mr. Shegog holds an M.B.A. from the Tepper School of Management at Carnegie Mellon University and a bachelor’s degree in electrical engineering from Lafayette College.Royal Danish Army.

EXECUTIVE OFFICER AND DIRECTOR COMPENSATION

Summary Compensation Table

The following table presents information regarding the total compensation paid or accrued during the last two fiscal years for (1) our Chief Executive Officer, (2) our twonexttwo next most highly compensated executive officers who earned more than $100,000 during the fiscal year ended December 31, 20182021 and who were serving as executive officers as of such date, and (3) the Company’sour former Chief ExecutiveMedical Officer (collectively the “Named Executive Officers”).

Narrative Disclosure to Summary Compensation Table

Historically, the Company’s executive compensation program has reflected our innovative and growth- orientedgrowth-oriented corporate culture and is designed to attract, retain and incentivize and align executives with both short- and long-term company objectives. To date, the compensation of the Company’s Chief Executive Officer and our other executive officers has consisted of a combination of base salary, cash bonuses and long-term incentive compensation paid in the form of equity. The named executive officers, like all full-time employees, are eligible to participate in the Company’s health and welfare benefit plans. The Company will continue to evaluate its compensation values and philosophy and compensation plans and arrangements as circumstances require. The Company will review executive compensation from time to time at the discretion of the Compensation Committee. As part of this review process, the Board and Compensation Committee will apply the values and philosophy, while considering the compensation levels needed to ensure the organization’s executive compensation program remains competitive and aligns incentives with the goals of the organization.

Base Salary

In March 2018,2022, the Compensation Committee and the Board approved an annual increase in base salaries for certain employees effective as of January 1, 2022, resulting in an annual base salary of $397,901$595,128 for Dr. Brennan $366,488 for Mr. Shegog, and $401,980 for Mr. Gengos. In May 2018, the Board approved an annual increase in base salary for Dr. Brennan to $474,701 in connection with her appointment as Interim President and Chief Executive Officer and in October 2018 an increase to $490,000 in connection with her transition to President and Chief Executive Officer. In March 2019, the Compensation Committee and the Board approved base salary increases for certain members of the Company’s management team effective January 1, 2019, resulting in an annual base salary of $505,000 for Dr. Brennan and $377,500$410,592 for Mr. Shegog.Awad. In October 2019, the Company appointed Gregg Beloff as Interim Chief Financial Officer. Mr. Beloff is the founder and Managing Director of Danforth Advisors, LLC (“Danforth”). The Company entered into a Consulting Agreement with Danforth and will pay Danforth at an hourly rate for Mr. Beloff’s services, subject to an annual increase each year and will reimburse Danforth for expenses. Pursuant to the Consulting Agreement, the Company paid Danforth $225,472 in 2021 and $267,400 in 2020 for Mr. Beloff’s services.

Annual Bonuses

The Company’s employment agreements with its executive officers provide for the opportunity to earn a cash bonus based upon achievement of both corporate and individual goals determined by the Board based on a target percentage of annual base salary. In March 2019,2022, the Board awarded Dr. Brennan a cash bonus of $186,200,$313,225, which represented 38.0%55.0% of her annual base salary, in recognition of her services provided in the year ended December 31, 20182021 and in accordance with the terms of her amended employment agreement and bonus assessment. In March 2019,2022, the Compensation Committee awarded Mr. ShegogAwad a cash bonus of $103,300,$173,622, which represented 28.2%44.0% of his annual base salary in recognition of his services provided in the year ended December 31, 20182021 and in accordance with the terms of his employment agreement and bonus assessment.

2019 Stock16

Equity Awards

In 2019,2022, in connection with the Compensation Committee and the Board’s assessment of 20182021 performance, the Company granted the following options to its current named executive officers: Dr. Brennan was granted an option to purchase 185,000434,160 shares of common stock, and Mr. ShegogAwad was granted an option to purchase 58,500165,490 shares of common stock, with each option having an exercise price of $8.59$1.95 per share and subject to vesting at a rate of 1/48th of the total number of shares subject thereto per month over four years. Additionally, Dr. Brennan was granted 106,920 shares of restricted common stock, and Mr. Awad was granted 40,820 shares of restricted common stock, each subject to vesting in equal annual installments over four years. In December 2021, the Company made a one-time grant of an option to Mr. Beloff to purchase an aggregate of 50,000 shares of the Company’s common stock at an exercise price of $2.34 per share (the fair market value on the date of the grant) which option will vest on a monthly basis in 1/12 increments starting November 1, 2021, with 100% of the shares to be vested on November 1, 2022, so long as Mr. Beloff continues providing his services to the Company, and otherwise to be in accordance with the Company’s form of stock option agreement, provided however, that an aggregate of 50% of the shares covered by the option shall be vested immediately if the Company terminates Mr. Beloff’s services before May 1, 2022.

Outstanding Equity Awards at Fiscal Year End

The following table presents the outstanding equity awards held by each of the named executive officers as of December 31, 2018.2021. All equity awards set forth in the table below were granted under the 2015 Stock Incentive Plan except for the awards with a grant date of May 15, 2017 which were granted under the 2017 Equity Incentive Award Plan.

Synlogic Reorganization

Employment and Merger

Synlogic, LLC completed a corporate reorganization from an LLC to a corporation on May 15, 2017. As part of the reorganization, equity incentive awards granted by Synlogic, LLC were converted into equity incentive awards for shares of Private Synlogic common stock. Common units of Synlogic, LLC were converted one for one into shares of Private Synlogic common stock and incentive units of Synlogic, LLC were converted into a number of shares of Private Synlogic common stock equal to (x) the value of the appreciation of such incentive units between the date of grant and immediately prior to the reorganization divided by (y) the value of a share of Private Synlogic common stock on the date of such reorganization. To the extent that such shares of Private Synlogic common stock were unvested, they remained Private Synlogic restricted stock. All shares of

Private Synlogic restricted stock were issued under the Private Synlogic 2017 Stock Incentive Plan which was assumed by the Company in the Merger and continue to vest on the same schedule as the original restricted stock awards.

All equity awards set forth above are set forth on a post-Merger basis. Pursuant to the terms of the Merger Agreement and after giving effect to the 1:7 reverse stock split, at the effective time of the Merger (the “Effective Time”), each outstanding share of capital stock of Private Synlogic was converted into the right to receive approximately 0.5532 shares of Company common stock on a post-Merger basis (the “Exchange Ratio”). In addition, at the Effective Time, the Company assumed all outstanding options to purchase shares of common stock of Private Synlogic, which were exchanged for options to purchase shares of the Company’s common stock, in each case appropriately adjusted based on the Exchange Ratio and all shares of Private Synlogic restricted stock were exchanged for shares of Company common stock in accordance with the Exchange Ratio and continue to vest on the same schedule as the original restricted stock awards.

EmploymentConsulting Agreements and Potential Payments Upon Termination of Employment or Change in Control

The Company has entered into employment agreements with each of our named executive officers as described below, as well as standard confidential information and/or inventions assignment agreements under which each of the named executive officers has agreed not to disclose confidential information. These employment agreements provide for “at will” employment.

Aoife M. Brennan, MB, BCh, BAO, MMSc

We originally entered into an employment agreement with Dr. Brennan in June 2016 that initially provided for a base salary of $345,000, subject to review and adjustment. Dr. Brennan’s base salary was subsequently increased to $349,036 for 2017 and $397,901 for 2018. Pursuant to the June 2017 amendment to the original employment agreement, Dr. Brennan was eligible to earn an annual cash incentive bonus of up to 30% of her base salary based on the achievement of corporate and/or individual performance goals, as determined by the Board. Dr. Brennan is also eligible to participate in the employee benefit plans available to employees, subject to the terms of those plans. In addition, Dr. Brennan’s original employment agreement, as amended, also provided her with a signing bonus of $85,000, plus a gross up for taxes to be paid on such compensation in connection with her commencement of employment.

In connection with her appointment as Interim President and Chief Executive Officer, we entered into an amendment to Dr. Brennan’s employment arrangement in June 2018, pursuant to which Dr. Brennan received (i) an additional cash payment of $6,400 per calendar month for the period which Dr. Brennan served as Interim President and Chief Executive Officer, (ii) a target bonus of 40% for the period which Dr. Brennan served as Interim President and Chief Executive Officer and (iii) a grant of an option to purchase an aggregate of 54,000 shares of the Company’s common stock at an exercise price of $9.55 (the fair market value on the date of the grant) which option vests in equal monthly installments for 48 months.

In connection with her appointment as President and Chief Executive Officer in October 2018, we entered into an amended and restated employment arrangement with Dr. Brennan (the “Amended and Restated Employment Agreement”), pursuant to which Dr. Brennan was entitled to receive (i) an annual base salary of $490,000 commencing as of October 2, 2018 (the “CEO Salary”), (ii) a target bonus of 40% of the CEO Salary and (iii) aone-time grant of an option to purchase an aggregate of 150,000 shares of common stock at an exercise price of $7.91 (the fair market value on the date of the grant), which option will vest as toone-fourth of the shares on the first anniversary of Dr. Brennan’s start date as President and Chief Executive Officer and as to the remainder in equal monthly installments for the following 36 months, continuing for so long as Dr. Brennan continues to serve as the Company’s President and Chief Executive Officer. In March 2019, the Board, upon recommendation of the Compensation Committee, approved an increase in Dr. Brennan’s base salary to $505,000, effective as of January 1, 2019, and an increase in the target annual cash bonus amount for 2019 for Dr. Brennan from 40% of base salary to 50% of base salary. In March 2022, the Board, upon recommendation of the Compensation Committee, approved an increase in Dr. Brennan’s base salary to $595,128, effective as of January 1, 2022.

The Amended and Restated Employment Agreement provides that, in the event that Dr. Brennan’s employment is terminated for any reason other than for “cause,” death or “disability,” or by Dr. Brennan for “good reason” (each as defined in the Amended and Restated Employment Agreement), she will be entitled to receive (i) continuing severance pay at a rate equal to 100% of her base salary, as then in effect, for a period of 12 months from the date of such termination, to be paid periodically in accordance with normal Company payroll practices; (ii) the right to continue health care benefits under COBRA, paid by the Company until the earlier of (a) 12 months from termination, or (b) the date on which Dr. Brennan becomes eligible for healthcare insurance with a subsequent employer, and (iii) alump-sum payment equal to the prorated portion of the target bonus for the fiscal year in which Dr. Brennan is terminated.

The Amended and Restated Employment Agreement provides that, in the event Dr. Brennan’s employment is terminated on account of death, “disability,” resignation for “good reason” or without “cause,” in any case, within the12-month period immediately following or the30-day period immediately prior to a “change in control,” then Dr. Brennan’s outstanding unvested restricted stock and/or options shall become fully vested.

In addition, Dr. Brennan has entered into anon-solicitation andnon-competition agreement that applies for 12 months following her employment.

Todd ShegogAntoine (Tony) Awad

We entered into an employment agreement with Mr. ShegogAwad in June 2016 thatDecember 2018 as Head of Technical Operations, which initially provided for a(i) an annual base salary of $345,000, subject to review and adjustment. Mr. Shegog’s base salary was increased to $349,036 for 2017 and $366,488 for 2018. In February 2019, Mr. Shegog’s base salary was increased to $377,500, effective$325,000 commencing as of January 1, 2019. Pursuant to the May 8, 2017 amendment to his employment agreement, Mr. Shegog was eligible to earn an annual cash incentiveDecember 17, 2018 (the “Start Date”), (ii) a target bonus of up to 30% of his base salary based on the achievement of corporate and/or individual performance goals, as determined by the Board.Board, (iii) a one-time grant of an option to purchase an aggregate of 55,000 shares of common stock at an exercise price of $8.69 (the fair market value on the date of the grant), which option will vest as to one-fourth of the shares on the first anniversary of Mr. Shegog is also eligibleAwad’s start date as Head of Technical Operations and as to participatethe remainder in equal monthly installments for the following 36 months, continuing for so long as Mr. Awad continues to serve as the Company’s Head of Technical Operations, and (iv) a sign-on bonus in the employee benefit plans availableamount of $25,000, less any applicable withholding or other taxes, paid out by December 31, 2018.

In connection with his appointment as Chief Operating Officer in July 2020, the Board, upon recommendation of the Compensation Committee, approved: (1) an increase in Mr. Awad’s base salary to employees, subject$376,000, effective as of July 1, 2020, (ii) a target bonus of 40% and (iii) a grant of an option to purchase an aggregate of 70,000 shares of the termsCompany’s common stock at an exercise price of those plans.$1.85 (the fair market value on the date of the grant) which option vests in equal monthly installments for 48 months. In March 2019,2022, the Board, upon recommendation of the Compensation Committee, approved an increase in the target annual cash bonus amount for 2019 for Mr. Shegog from 30% ofAwad’s base salary to 40%$410,592, effective as of base salary.January 1, 2022.

Mr. Shegog’sAwad’s employment agreement provides that, in the event that Mr. Shegog’sAwad’s employment is terminated for any reason other than for “cause,” death or “disability,” or by Mr. ShegogAwad for “good reason” (each as defined in his employment agreement), he will be entitled to receive (i) continuing severance pay at a rate equal to 100% of his base salary, as then in effect, for a period of six months from the date of such termination, to be paid periodically in accordance with normal Company payroll practices; (ii) the right to continue health care benefits under COBRA, paid by the Company until the earlier of (a) six months from termination, or (b) the date on which Mr. ShegogAwad becomes eligible for healthcare insurance with a subsequent employer, and (iii) alump-sum payment equal to the prorated portion of the target bonus for the fiscal year in which Mr. ShegogAwad is terminated.

Mr. Shegog’sAwad’s employment agreement provides that, in the event Mr. Shegog’sAwad’s employment is terminated on account of death, “disability,” resignation for “good reason” or without “cause,” in any case, within the12-month period immediately following or the30-day period immediately prior to a “change in control,” then Mr. Shegog’sAwad’s outstanding unvested restricted stock and/or options shall become fully vested.

In addition, Mr. ShegogAwad has entered into anon-solicitation andnon-competition agreement that applies for 12 months following his employment.

18

Richard Riese, M.D., Ph.D.

We entered into an employment agreement with Dr. Riese in July 2019 as Chief Medical Officer, that initially provided for (i) an annual base salary of $400,000 commencing as of September 16, 2019 (the “Start Date”), (ii) a target bonus of 40% of his base salary based on the achievement of corporate and/or individual performance goals, as determined by the Board, (iii) a one-time grant of an option to purchase an aggregate of 150,000 shares of common stock at an exercise price of $2.58 (the fair market value on the date of the grant), which option will vest as to one-fourth of the shares on the first anniversary of Dr. Riese’s start date as Chief Medical Officer and as to the remainder in equal monthly installments for the following 36 months, continuing for so long as Dr. Riese continues to serve as the Company’s Chief Medical Officer, and (iv) a sign-on bonus in the amount of $50,000, less any applicable withholding or other taxes, payable in the first quarter of 2020.

In March 2021, the Board, upon recommendation of the Compensation Committee, approved an increase in Dr. Riese’s base salary to $426,420, effective as of January 1, 2021.

Dr. Riese’s employment agreement provided that, in the event that Dr. Riese’s employment was terminated for any reason other than for “cause,” death or “disability,” or by Dr. Riese for “good reason” (each as defined in his employment agreement), he would be entitled to receive (i) continuing severance pay at a rate equal to 100% of his base salary, as then in effect, for a period of six months from the date of such termination, to be paid periodically in accordance with normal Company payroll practices; (ii) the right to continue health care benefits under COBRA, paid by the Company until the earlier of (a) six months from termination, or (b) the date on which Dr. Riese becomes eligible for healthcare insurance with a subsequent employer, and (iii) a lump-sum payment equal to the prorated portion of the target bonus for the fiscal year in which Dr. Riese is terminated.

Dr. Riese’s employment agreement provided that, in the event Dr. Riese’s employment was terminated on account of death, “disability,” resignation for “good reason” or without “cause,” in any case, within the 12-month period immediately following or the 30-day period immediately prior to a “change in control,” then Dr. Riese’s outstanding unvested restricted stock and/or options would become fully vested.

In addition, Dr. Riese has entered into a non-solicitation and non-competition agreement that applies for 12 months following his employment.

Dr. Riese resigned as our Chief Medical Officer, effective July 29, 2021, in order to pursue another opportunity.

The following definitions apply to Dr. Brennan’s and Mr. Shegog’sAwad’s employment agreements:agreements, and prior to his resignation, Dr. Riese’s employment agreement:

“Cause” is defined as the executive’s (i) conviction of a felony, plea of guilty or “no contest” to a felony, or confession of guilt to a felony, in each case whether or not in connection with the performance of the executive’s

duties to the Company,; (ii) act or omission which constitutes willful misconduct or negligence that results in loss, damage or injury to the Company or its prospects, including, but not limited to (A) disloyalty, dishonesty or a breach of fiduciary duty to the Company or Stockholders, (B) theft, fraud, embezzlement or other illegal conduct, or (C) deliberate disregard of a rule or policy of the Company; (iii) failure, refusal or unwillingness to perform, to the reasonable satisfaction of the Board determined in good faith, any duty or responsibility assigned to the executive, which failure of performance continues for a period of more than two weeks after written notice thereof has been provided by the Board, setting forth in reasonable detail the nature of such failure of performance; or (iv) the material breach by the executive of any of the provisions of the employment agreement or its related agreements.

“Good reason” is defined as a resignation that occurs within 30 days following: (i) a change in the principal location at which the executive provides services to the Company beyond 50 miles from Cambridge, Massachusetts; (ii) a reduction in the executive’s compensation or a material reduction in the executive’s benefits, except such a reduction in connection with a general reduction in compensation or other benefits of all senior executives of the Company; (iii) a material breach of the executive’s employment agreement by the Company that has not been cured within 10 days after written notice thereof by the executive; or (iv) a failure by the Company to obtain the assumption of the employment agreement by any successor of the Company.

“Disability” is defined as the executive’s inability, due to physical or mental illness or disease, to perform the functions then performed by the executive for 180 consecutive days, accompanied by the likelihood, in the opinion of a physician chosen by the Company and reasonably acceptable to the executive, that the executive will be unable to perform such functions within the reasonably foreseeable future, provided that the foregoing definition shall not include a disability for which the Company is required to provide reasonable accommodation pursuant to the Americans with Disabilities Act or other similar statute or regulation.

“Change in control” is defined as (i) the sale of the Company by merger in which the stockholders in their capacity as such no longer own a majority of the outstanding equity securities of the Company (or its successor); (ii) any sale of all or substantially all of the assets or capital stock of the Company (other than in aspin-off or similar transaction) or (iii) any other acquisition of the business of the Company, as determined by the board of directors in its sole discretion. For the avoidance of doubt, in no event shall a bona fide equity or debt financing, including a financing in which greater than 50% of the Company’s outstanding equity securities are acquired by a third-party, be deemed a “change in control.”

Gregg Beloff

In October 2019, we entered into a Consulting Agreement with Danforth, as amended, pursuant to which Danforth will provide finance, accounting and administrative functions to the Company, including the services to be provided by Mr. Beloff as the Company’s Interim Chief Financial Officer, principal accounting officer and principal financial officer. The Company entered into a Consulting Agreement with Danforth and will pay Danforth at an hourly rate for Mr. Beloff’s services, subject to an annual increase each year and will reimburse Danforth for expenses. The Consulting Agreement’s term continues until either party gives notice of termination. The Consulting Agreement may be terminated by the Company or Danforth with cause, upon 10 days written notice and without cause, upon 30 days written notice. The Company also made a one-time grant of an option to Mr. Beloff to purchase an aggregate of 50,000 shares of the Company’s common stock at an exercise price of $2.30 per share (the fair market value on the date of the grant) which vested with respect to 25% of the shares six months from the date of the grant date and with respect to the remaining 75% in equal monthly instalments over the subsequent 18 months.  In December 2021, the Company made a one-time grant of an option to Mr. Beloff to purchase an aggregate of 50,000 shares of the Company’s common stock at an exercise price of $2.34 per share (the fair market value on the date of the grant) which option will vest on a monthly basis in 1/12 increments starting November 1, 2021, with 100% of the shares to be vested on November 1, 2022, so long as Mr. Beloff continues providing his services to the Company, and otherwise to be in accordance with the Company’s form of stock option agreement, provided however, that an aggregate of 50% of the shares covered by the option shall be vested immediately if the Company terminates Mr. Beloff’s services before May 1, 2022.

Other Benefits

Executive officers are eligible to participate in all of the Company’s employee benefit plans, including life insurance, medical, dental, vision, group life, short and vision,long-term disability, a 401(k)-retirement retirement plan, an Employee Stock Purchase Plan (ESPP), and a flex spending account plan.plan, in each case on the same basis as other employees, subject to applicable laws. We also providepaid-time-off benefits to all similarly-situatedemployees, including our executive officers.

401(k) Retirement Plan

We maintain a defined contribution retirement plan for our eligible employees.

Terms and Conditions Employees are eligible to participate in the plan beginning on their date of Dr. Gutierrez-Ramos’s Separation Agreement

On May 10, 2018, we entered into an agreement (the “Gutiérrez-Ramos Separation Agreement”) with Dr. Gutiérrez-Ramos related to his resignation as our President and Chief Executive Officer that provides Dr. Gutiérrez-Ramos the following severance and benefits: (i) continued payments of his base salary for 13 months following his cessation of employment; (ii) continued vesting of all of his outstanding equity awards in accordance with their terms through June 9, 2018; (iii) payment or reimbursement of COBRA premiums for Dr. Gutiérrez-Ramos for up to 13 months following his cessation of employment or until the date on which Dr. Gutiérrez-Ramos becomes eligible for healthcare insurance with a subsequent employer; and (iv) alump-sum payment of $83,592 equal to the prorated portion of Dr. Gutiérrez-Ramos’ target bonus for 2018. In addition, pursuant tohire. Under the terms of the Gutiérrez-Ramos Separation Agreement, Dr. Gutiérrez-Ramos continuedplan, employees may make voluntary contributions as a percentage of compensation, up to veststatutory limits. Under our 401(k) plan, each employee is fully vested in his previously granted restricted stock award grant dated May 14, 2015 until November 15, 2018.

The Gutiérrez-Ramos Separation Agreement includes a release of claimsor her deferred salary contributions. Employee contributions are held and invested by Dr. Gutiérrez-Ramos against us. In connection with the entry into the Gutiérrez-Ramos Separation Agreement, Dr. Gutiérrez-Ramos agreed that he would continueplan’s trustee. Our 401(k) plan also permits us to bemake discretionary and matching contributions, subject to established limits. We started to match employee contributions effective January 1, 2019. We matched 50% of the Invention andNon-Disclosure Agreement and theNon-Compete andNon-Solicitation Agreement between us and Dr. Gutiérrez-Ramos that contains a covenant protecting our confidential information.

Terms and Conditions of Mr. Gengos’ Separation Agreement

On December 17, 2018, the Company entered into a separation agreement (the “Gengos Separation Agreement”) with Mr. Gengos, pursuant to which Mr. Gengos’ employment with the Company was terminated without cause as a result of his role at the Company being materially diminished. Pursuantemployee contributions to the terms401(k) plan up to a maximum of 4% of the Gengos Separation Agreement, Mr. Gengos was employed byparticipating employee’s eligible earnings, resulting in a maximum company match of 2% of the Company as its Chief Operating Officerparticipating employee’s eligible earnings, and Headsubject to certain additional statutory dollar limitations. In 2021, our Compensation Committee approved the increase in the Company’s matching contribution to 50% of Corporate Development through January 15, 2019.

Under the Gengos Separation Agreement, in exchange for a full general release of claims and continued compliance with the Invention and Nondisclosure Agreement and theNon-Competition andNon-Solicitation Agreement entered into between Mr. Gengos and the Company, which covers a period of 12 months following his employment, Mr. Gengos will receive: (i) continued payments of his base salary for six months following his cessation of employment; (ii) continued vesting of all of his outstanding equity awards in accordance with their terms through his cessation of employment; (iii) payment or reimbursement of COBRA premiums for Mr. Gengos foremployee contributions up to six months following his cessationa maximum of employment or until6% of the date on which Mr. Gengos becomesparticipating employee’s eligible earnings, resulting in a maximum company match of 3% of the participating employee’s eligible earnings, and subject to certain additional statutory dollar limitations. This increase in the Company’s matching contributions was retroactive for healthcare insurance with a subsequent employer; and (iv)(a) alump-sumall 2021 contributions. payment amount of $121,558.78 equal to Mr. Gengos’ target bonus for 2018 and (b) alump-sum payment amount of $5,781.91 equal to Mr. Gengos’ target bonus for 2019,pro-rated for 15 days.

20,000 54,000 shares of our common stock (subject to adjustment as provided in the applicable equity plan). In addition, eachnon-employee director who has been serving as a director for at least three months prior to any annual stockholder meeting and will continue to serve as a director immediately following such annual stockholder meeting will be automatically granted, on the date of such annual stockholder meeting, an option (the Annual Grant) to purchase 10,00027,000 shares of our common stock (subject to adjustment as provided in the applicable equity plan). The Initial Grant will vest in substantially equal installments on each of the first three anniversaries of the applicable grant date, subject to continued service through each applicable vesting date, and the Annual Grant will vest in full on the earlier of the first anniversary of the applicable grant date or immediately prior to the next annual stockholder meeting after the applicable grant date, subject to continued service through such vesting date. In addition, pursuant to the terms of the Amended and Restated Director Compensation Program, all equity awards outstanding and held by anon-employee director will vest in full immediately prior to the occurrence of a change in control.

We reimburse ournon-employee directors for all reasonable and customary business expenses incurred providing services to us in accordance with Company policy.