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Sigilon Therapeutics, Inc.

100 Binney Street, Suite 600

Cambridge, MA 02142

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Sigilon Therapeutics, Inc.

100 Binney Street, Suite 600

Cambridge, MA 02142

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When were this proxy statement and the accompanying materials sent to stockholders?

On or about April 14, 2022, we began sending the Notice of Proxy Materials to all stockholders entitled to vote at the Annual Meeting.

When is the record date for the Annual Meeting?

The Company’s Board of Directors has fixed the record date for the Annual Meeting as of the close of business on April 7, 2022. Only stockholders who owned our common stock at the close of business on April 7, 2022 are entitled to vote at the Annual Meeting.

How many votes can be cast by all stockholders?

A total of 32,399,257 shares of common stock of the Company were outstanding on April 7, 2022 and are entitled to be voted at the meeting. Each share of common stock is entitled to one vote on each matter.

How do I vote?

If you are a stockholder of record and your shares are registered directly in your name, you may vote:

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If your shares of common stock are held in street name (held for your account by a broker or other nominee), please follow the instructions you receive from them to vote your shares.

What are the Board’s recommendations on how to vote my shares?

The Board of Directors recommends a vote:

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Who pays the cost for soliciting proxies?

Sigilon will bear the cost of solicitation of proxies. This includes the charges and expenses of brokerage firms and others for forwarding solicitation material to beneficial owners of our outstanding common stock. Sigilon may solicit proxies by mail, personal interview, telephone or via the Internet through its officers, directors and other management employees, who will receive no additional compensation for their services.

Can I change my vote?

You may revoke your proxy at any time before it is voted by notifying the Secretary in writing, by returning a signed proxy with a later date, by transmitting a subsequent vote over the Internet or by telephone prior to the close of the Internet voting facility or the telephone voting facility, or by attending the meeting and voting in person. If your stock is held in street name, you must contact your broker or nominee for instructions as to how to change your vote.

How is a quorum reached?

The presence, in person or by proxy, of holders of at least a majority of the total number of outstanding shares entitled to vote is necessary to constitute a quorum for the transaction of business at the Annual Meeting. Abstentions and “broker non-votes” (i.e., shares represented at the meeting held by brokers, bankers or other nominees as to which instructions have not been received from the beneficial owners or persons entitled to vote such shares and, with respect to one or more but not all proposals, such brokers or nominees do not have discretionary voting power to vote such shares), if any, will be counted for purposes of determining whether a quorum is present for the transaction of business at the meeting.

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What vote is required to approve each item?

A “broker non-vote” occurs when a broker, bank or other nominee holding shares for a beneficial owner does not vote the shares on a proposal because the broker, bank or other nominee does not have discretionary voting power for a particular item and has not received instructions from the beneficial owner regarding voting. Brokers, banks or other nominees who hold shares for the accounts of their clients have discretionary authority to vote shares if specific instructions are not given with respect to routine matters. Although the determination of whether a broker, bank or other nominee will have discretionary voting power for a particular item is typically determined only after proxy materials are filed with the SEC, we expect that the election of each nominee for director (Proposal 1) will be a non-routine matter and that the proposal on ratification of the appointment of our independent registered public accounting firm (Proposal 2) will be a routine matter.

If the Annual Meeting is adjourned or postponed for any purpose, at any subsequent reconvening of the meeting, your proxy will be voted in the same manner as it would have been voted at the original convening of the Annual Meeting unless you withdraw or revoke your proxy.

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Could other matters be decided at the Annual Meeting?

We do not know of any other matters that may be presented for action at the Annual Meeting. Should any other business come before the meeting, the persons named on the enclosed proxy will have discretionary authority to vote the shares represented by such proxies in accordance with their best judgment. If you hold shares through a broker, bank or other nominee as described above, they will not be able to vote your shares on any other business that comes before the Annual Meeting unless they receive instructions from you with respect to such matter.

What happens if the meeting is postponed or adjourned?

Your proxy may be voted at the postponed or adjourned meeting. You will still be able to change your proxy until it is voted.

What does it mean if I receive more than one proxy card or voting instruction form?

It means that you have multiple accounts at the transfer agent or with brokers. Please complete and return all proxy cards or voting instruction forms to ensure that all of your shares are voted.

Who should I call if I have any additional questions?

If you hold your shares directly, please call Matthew Kowalsky, Secretary of the Company, at (617) 336-7540. If your shares are held in street name, please contact the telephone number provided on your voting instruction form or contact your broker or nominee holder directly.

Electronic Delivery of Company Stockholder Communications

Most stockholders can elect to view future proxy materials and annual reports over the Internet instead of receiving paper copies in the mail. You can choose this option and save us the cost of producing and mailing these documents by following the instructions provided when you vote over the Internet.

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(12)Includes options to purchase 1,378,476 shares of common stock that are exercisable within 60 days of April 7, 2022.

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MANAGEMENT AND CORPORATE GOVERNANCE

BOARD COMPOSITION AND STRUCTURE

Our certificate of incorporation states that the Board of Directors shall consist of not fewer than three and not more than fifteen members, and the precise number of directors shall be fixed by a resolution of the Board of Directors. Each director shall hold office until his or her successor is duly elected and qualified or until his or her earlier death, resignation or removal. Our certificate of incorporation provides that our directors may be removed only for cause by the affirmative vote of the holders of a majority of the voting power of the outstanding shares of capital stock of the Company entitled to vote generally in the election of directors, voting together as a single class, at a meeting of the stockholders called for that purpose. Any vacancy in the Board of Directors, including a vacancy that results from an increase in the number of directors, may be filled by a vote of the majority of the directors then in office.

Our certificate of incorporation provides that the Board of Directors is divided into three classes of directors, with the classes as nearly equal in number as possible. Each of our directors identified below serves in the class indicated. Subject to any earlier resignation or removal in accordance with the terms of our restated certificate of incorporation and bylaws, our Class I directors will serve until the 2024 annual meeting of stockholders; our Class II directors who are re-elected at the 2022 annual meeting of stockholders will serve until the 2025 annual meeting of stockholders; and our Class III directors will serve until the 2023 annual meeting of stockholders. Any additional directorships resulting from an increase in the number of directors will be apportioned by the Board among the three classes.

The Board of Directors is currently comprised of eight members. Below is a list of the names, ages as of April 7, 2022 and classification of the individuals who currently serve as our directors.

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DIRECTOR BIOGRAPHIES

Information concerning our directors is set forth below. The biographical description of each director includes the specific experience, qualifications, attributes and skills that led to the Board of Directors’ conclusion at the time of filing of this proxy statement that each person listed below should serve as a director.

CLASS II DIRECTOR NOMINEES

Rogerio Vivaldi Coelho, M.D., has served as our President and Chief Executive Officer and as a member of our Board of Directors since 2018. Prior to joining Sigilon, Dr. Vivaldi served as Executive Vice President and Chief Global Therapeutics Officer at Bioverativ Inc. from 2016 until it was acquired by Sanofi in 2018, and served as Chief Commercial Officer at Spark Therapeutics between 2014 and 2016. Before that he led Genzyme’s rare disease business as President of both the rare disease business and the renal & endocrine group, as well as Senior Vice President and General Manager of Genzyme’s Latin America Group during his 20-year tenure at Genzyme. Dr. Vivaldi serves on the Board of Directors of Crinetics Pharmaceuticals, Inc. (Nasdaq: CRNX). Dr. Vivaldi holds his medical degree from the Universidade do Rio de Janeiro. He completed a residency in endocrinology at the Universidade do Estado do Rio de Janeiro and a fellowship at Mount Sinai Hospital Center in New York in the department of genetics, focusing on Gaucher disease. Dr. Vivaldi holds an M.B.A. degree from COPPEAD, Universidade Federal do Rio de Janeiro. We believe that Dr. Vivaldi is qualified to serve on our Board of Directors based on his extensive experience in the

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pharmaceutical industry and his expansive knowledge of our company due to his role as our President and Chief Executive Officer.

John Cox has served as a member of our Board of Directors since 2019. Mr. Cox has served as the Chief Executive Officer of Repertoire Immune Medicines since 2019, and was formerly the Chief Executive Officer of Bioverativ Inc. from 2017 until 2019, which he built, grew, and led to a successful acquisition by Sanofi S.A. Previously, Mr. Cox was Executive Vice President, Global Commercial & Technical Operations at Biogen Inc. from 2016 until 2017, where he was a member of the leadership team and was globally responsible for all aspects of an $11 billion commercial operation, as well as technical development and all drug supply. Prior to that he served as Executive Vice President of Pharmaceutical Operations & Technology at Biogen Inc. from 2015 until 2016, in which capacity he oversaw the company’s production facilities, supply chain operations, technical development, quality and engineering across the globe. He also had responsibility for the creation of the company’s biosimilar business, including its successful commercialization in Europe. Mr. Cox holds an M.B.A. from the University of Michigan, an M.S. in cell biology from California State University and a B.S. in biology from Arizona State University. We believe that Mr. Cox is qualified to serve on our Board of Directors based on his experience in the pharmaceutical industry.

Kavita Patel, M.D., has served as a member of our Board of Directors since 2020. Dr. Kavita Patel is a practicing physician in Washington, D.C., and was a Nonresident Fellow at the Brookings Institution, where her research and reports focused on patient-centered care, payment and delivery systems and health reform. She previously served in the Obama Administration as Director of Policy for the Office of Intergovernmental Affairs and Public Engagement in the White House. She also served as a policy analyst and aide to the late Senator Edward Kennedy. As Deputy Staff Director on Health, she was part of the senior staff of the Health, Education, Labor and Pensions (HELP) Committee under Senator Kennedy’s leadership. Dr. Patel also served as the Managing Director of Clinical Transformation at the Center for Health Policy at the Brookings Institution and Vice President of Payer and Provider Strategy at Johns Hopkins Health System. Dr. Patel currently serves on the Board of Directors of SelectQuote, Inc. Dr. Patel serves on the board of several non-profit organizations, including Dignity Healthcare and SSM Healthcare. She earned her M.D. from the University of Texas Health Science Center and her M.P.H. from the University of California, Los Angeles. We believe that Dr. Patel is qualified to serve on our Board of Directors based on her extensive experience as a medical practitioner.

CURRENT DIRECTORS NOT STANDING FOR ELECTION AT THE ANNUAL MEETING

Douglas Cole, M.D., has served as a member of our Board of Directors since 2016. Dr. Cole joined Flagship Pioneering, which conceives, creates, resources and develops first-in-category bioplatform companies, in 2001, and is currently a Managing Partner focused on life science investments. Dr. Cole currently serves on the Board of Directors of Denali Therapeutics, Foghorn Therapeutics, Sana Biotechnology and a number of private companies. In the past five years, Dr. Cole served on the boards of directors of Quanterix Corporation and Editas Medicine. Dr. Cole received his M.D. from the University of Pennsylvania School of Medicine and his B.A. in English from Dartmouth College. We believe that Dr. Cole is qualified to sit on our Board of Directors due to his substantial experience as an investor in emerging biopharmaceutical and life sciences companies, as well as his experience serving on the boards of directors of multiple public and private bioplatform companies.

Robert R. Ruffolo, Jr., Ph.D., has served as a member of our Board of Directors since 2016. He served as the President of Research and Development and as the Corporate Senior Vice President of Wyeth Pharmaceuticals from 2002 through 2008. In these roles, he managed an R&D organization of 9,000 scientists with an annual budget in excess of $3 billion. From 2000 to 2002 he served as an Executive Vice President at Wyeth Pharmaceuticals, where he was responsible for Pharmaceutical Research and Development. Prior to joining Wyeth Pharmaceuticals, Dr. Ruffolo spent 17 years at SmithKline Beecham Pharmaceuticals plc (now GlaxoSmithKline plc) where he was Senior Vice President and Director of Biological Sciences, Worldwide from 1984 to 2000. Before joining SmithKline Beecham Pharmaceuticals plc, Dr. Ruffolo spent six years at Eli Lilly and Company from 1978 to 1984 where he was a Senior Pharmacologist. Dr. Ruffolo currently serves on the boards of directors of Aridis Pharmaceuticals, Inc., Diffusion Pharmaceuticals, Inc. and several private companies. He received his B.S. in Pharmacy from The Ohio State University and his Ph.D. in Pharmacology from The Ohio State University. We believe that Dr. Ruffolo is qualified to serve as a

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member of our Board of Directors due to his extensive experience in the pharmaceutical industry and his technical and management expertise in product discovery and development.

Stephen Oesterle, M.D., has served as a member of our Board of Directors since 2016. Dr. Oesterle is a consultant, advising private equity and operating companies in the healthcare industry. From 2002 to 2015, he served as a member of the Executive Committee of Medtronic plc, a global medical technology, services and solutions company, and as Medtronic plc’s Senior Vice President, Medicine and Technology. Previously, he served as an Associate Professor of Medicine and Director of Invasive Cardiology Services at each of Massachusetts General Hospital from 1998 to 2002, Stanford University Medical Center from 1992 to 1998, and Georgetown University Medical Center from 1991 to 1992. Dr. Oesterle has served as a member of the Board of Directors of Baxter International Inc. since 2017, Peijia Medical Limited since 2020, and Paragon28 since 2021. He served as a director of REVA Medical, Inc. from February 2018 to May 2019 and HeartWare International, Inc. from January 2016 to November 2016, prior to Medtronic plc’s acquisition of HeartWare International, Inc. We believe that Mr. Oesterle is qualified to serve on our Board of Directors based on his extensive experience in the pharmaceutical industry as well as his experience serving on various public and private company boards.

Eric Shaff has served as a member of our Board of Directors since 2017. Mr. Shaff is President and Chief Executive Officer of Seres Therapeutics, Inc., a role that follows a series of leadership positions at Seres Therapeutics, Inc. beginning in 2015. Prior to Seres Therapeutics, Inc., Mr. Shaff worked at Momenta Pharmaceuticals, Inc. and Genzyme Corporation, where he served as global head of finance of Genzyme’s Rare Genetic Disease Division in addition to roles in corporate development and corporate Finance. Mr. Shaff has also worked in corporate finance at Pfizer Inc. and in investment banking with Broadview International LLC (now Jefferies Broadview). Mr. Shaff earned a B.A. from the University of Pennsylvania and holds an M.B.A. from the Johnson Graduate School of Management at Cornell University. We believe that Mr. Shaff is qualified to serve on our Board of Directors based on his extensive experience and executive leadership roles in the pharmaceutical industry.

Brooke Story has served as a member of our board of directors since 2021. Currently, Ms. Story serves as President of BD Integrated Diagnostic Solutions, where she is responsible for driving global strategic, operational and commercial performance and customer experience across a portfolio of diagnostic solutions. Prior to joining BD, she served in roles of increasing responsibility at Medtronic for a period of more than fifteen years. Most recently, she served as President of Pelvic Health and Gastric Therapies at Medtronic from December 2018 to March 2021. She also held leadership roles in sales and marketing within Medtronic’s Restorative Therapies Group from 2016 to 2018. She received a number of awards for her efforts to bring new technologies and therapies to market while at Medtronic, including the Wallin Award and Star of Excellence. She also served as a Board observer for an early stage device company and chair of Medtronic’s African Descent Network, an organization responsible for supporting Medtronic’s mission driven goals of increasing inclusion and diverse representation in leadership. Ms. Story holds an M.B.A. from the University of Michigan and a B.S. in industrial engineering from the University of Tennessee. We believe that Ms. Story is qualified to serve as a member of our Board of Directors due to her experience in the life sciences industry and her operating and financial expertise.

Director Independence

Under the rules of the Nasdaq Stock Market, independent directors must comprise a majority of our Board of Directors. In addition, the rules of the Nasdaq Stock Market require that, subject to specified exceptions, each member of a listed company’s audit and compensation committees be independent and that director nominees be selected or recommended for the board’s selection by independent directors constituting a majority of the independent directors or by a nominating and corporate governance committee comprised solely of independent directors. Under the rules of the Nasdaq Stock Market, a director will only qualify as “independent” if, in the opinion of that company's Board of Directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director and that such person is “independent” as defined under Nasdaq Stock Market and the rules under the Securities Exchange Act of 1934, as amended, or the Exchange Act.

Audit Committee members must also satisfy the independence criteria set forth in Rule 10A-3 under the Exchange Act. In order to be considered independent for purposes of Rule 10A-3, a member of an audit committee of a

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listed company may not, other than in his or her capacity as a member of the Audit Committee, the Board of Directors or any other board committee: (1) accept, directly or indirectly, any consulting, advisory or other compensatory fee from the listed company or any of its subsidiaries or (2) be an affiliated person of the listed company or any of its subsidiaries.

Based upon information requested from and provided by each director concerning his or her background, employment and affiliations, including family relationships, our Board of Directors has determined that each of our directors, with the exception of Dr. Vivaldi, is an “independent director” as defined under applicable rules of the Nasdaq Stock Market. In addition, all members of our audit committee satisfy the independence criteria set forth in Rule 10A-3 under the Exchange Act, and all members of our compensation committee satisfy the independence criteria set forth in Rule 10C-1 under the Exchange Act and are “non-employee directors” as defined in Section 16b-3 of the Exchange Act. In making such determination, our Board of Directors considered the relationships that each such non-employee director has with our Company and all other facts and circumstances that our Board of Directors deemed relevant in determining his or her independence, including the beneficial ownership of our capital stock by each non-employee director. Dr. Vivaldi is not an independent director under these rules because he is our President and Chief Executive Officer.

Board Membership Criteria and Diversity

Our Nominating and Corporate Governance Committee is responsible for developing and recommending to our Board of Directors criteria for membership on the Board of Directors and, consistent with those criteria, recommending to the Board of Directors director candidates and nominees for the next annual meeting of stockholders taking into account each candidate’s ability, judgment and experience and the overall diversity and composition of the Board of Directors. As reflected in our Corporate Governance Guidelines, it is the policy of the Board of Directors that all directors should possess high standards of personal and professional ethics, integrity and values, and be committed to representing the long-term interests of the Company’s stockholders. The Board of Directors believes that each director should possess the requisite ability, judgment and experience to oversee the Company’s business, and should contribute to the overall diversity of the Board of Directors. The Board of Directors considers the qualifications of directors and director candidates individually and in the broader context of its overall composition and the Company’s current and anticipated future needs. The nominating and corporate governance committee does not have a written policy regarding stockholder nominations, but has determined that it is the practice of the committee to consider candidates proposed by stockholders if made in accordance with our bylaws.

Based upon responses to questionnaires received from each of our directors with respect to diversity, the Company’s Board of Directors is currently comprised of individuals from the following diverse backgrounds:

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Board Meetings and Attendance

The Board of Directors held six meetings during the year ended December 31, 2021. Each of the directors attended at least seventy-five percent (75%) of the meetings of the Board of Directors and the committees of the Board

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of Directors on which he or she served during the year ended December 31, 2021 (in each case, which were held during the period for which he or she was a director and/or a member of the applicable committee and excluding any meetings in which a director was an interested party).

While we do not have a formal policy regarding director attendance at the annual meeting of stockholders, we expect our Board members to prepare for, attend and participate in all Board and applicable committee meetings, including by means of remote communication.

Board of Directors Leadership Structure

Our current Board leadership structure separates the positions of Chief Executive Officer and Chairperson of the Board of Directors, although we do not have a corporate policy requiring that structure, and the Board believes that it is in the best interests of the Company for the Board to make a determination regarding whether or not to separate the roles of the Chairperson and the Chief Executive Officer based on the then-current circumstances. The Board believes that this separation is appropriate for the organization at this time because it allows for a division of responsibilities and a sharing of ideas between individuals having different perspectives. Our Chief Executive Officer, who is also a member of our Board of Directors, is primarily responsible for our operations and strategic direction, while our Board Chairperson, who is an independent member of the Board, is primarily focused on matters pertaining to corporate governance, including management oversight, and strategic guidance. While the Board believes that this is the most appropriate structure at this time, the Nominating and Corporate Governance Committee evaluates the Board leadership structure from time to time, and may recommend alterations of this structure in the future.

The Board of Directors’ Role in Risk Oversight

The Board of Directors plays an important role in risk oversight at Sigilon through direct decision-making authority with respect to significant matters, as well as through the oversight of management by the Board of Directors and its committees. In particular, the Board of Directors administers its risk oversight function through (1) the review and discussion of regular periodic reports by the Board of Directors and its committees on topics relating to the risks that Sigilon faces, (2) the required approval by the Board of Directors (or a committee of the Board of Directors) of significant transactions and other decisions, (3) the direct oversight of specific areas of Sigilon’s business by the Audit, Compensation and Nominating and Corporate Governance Committees, and (4) regular periodic reports from the auditors and other outside consultants regarding various areas of potential risk, including, among others, those relating to our internal control over financial reporting. The Board of Directors also relies on management to bring significant matters impacting Sigilon to the attention of the Board of Directors.

Pursuant to the Audit Committee’s charter, the Audit Committee is responsible for reviewing and discussing with management and Sigilon’s independent registered public accounting firm, Sigilon’s system of its critical accounting practices, and policies relating to risk assessment and management. As part of this process, the Audit Committee discusses Sigilon’s major financial risk exposures and steps that management has taken to monitor and control such exposure. In addition, the Audit Committee has established procedures for the receipt, retention and treatment of complaints received by the Company regarding accounting, internal accounting controls or auditing matters, and the confidential, anonymous submissions by employees of concerns regarding accounting, internal accounting controls, auditing and compliance matters.

Because of the role of the Board of Directors and the Audit Committee in risk oversight, the Board of Directors believes that any leadership structure that it adopts must allow it to effectively oversee the management of the risks relating to Sigilon’s operations. The Board of Directors acknowledges that there are different leadership structures that could allow it to effectively oversee the management of the risks relating to the Company’s operations and believes its current leadership structure enables it to effectively provide oversight with respect to such risks.

BOARD COMMITTEES

The Board of Directors has a standing Audit, Compensation and Nominating and Corporate Governance Committee. Each our Audit Committee, Compensation Committee and Nominating and Corporate Governance

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Committee is comprised solely of independent directors, and is described more fully below. Each committee operates pursuant to a written charter and each reviews and assesses the adequacy of its charter periodically and submits its charter to the Board for approval. The charters for each committee are all available on our website (www.sigilon.com) under the “Investors/Media” section.

The following table describes which directors currently serve on each of the Board of Directors’ committees.

Audit Committee

Our Audit Committee is composed of Stephen Oesterle, M.D., Eric Shaff and Brooke Story, with Mr. Shaff serving as Chair of the committee. Dr. Cole resigned from our Audit Committee in June 2021. The Board of Directors has determined that each member of the Audit Committee meets the independence requirements of Rule 10A-3 under the Exchange Act and the applicable listing standards of Nasdaq. The Board of Directors has determined that Eric Shaff is an “audit committee financial expert” within the meaning of the Securities and Exchange Commission, or SEC, regulations and applicable listing standards of Nasdaq. The Audit Committee’s responsibilities include:

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During the year ended December 31, 2021, the Audit Committee met five times. The report of the Audit Committee is included in this proxy statement under “Audit Committee Report.”

Nominating and Corporate Governance Committee

Our Nominating and Corporate Governance Committee is composed of Douglas Cole, M.D., Stephen Oesterle, M.D., and Kavita Patel, M.D., with Dr. Cole serving as Chair of the committee. The Board of Directors has determined that each member of the Nominating and Corporate Governance Committee is “independent” as defined under the applicable listing standards of Nasdaq. The Nominating and Corporate Governance Committee’s responsibilities include:

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During the year ended December 31, 2021, the Nominating and Corporate Governance Committee met one time.

Compensation Committee

Our Compensation Committee is composed of Douglas Cole, M.D., Robert Ruffolo, Jr., Ph.D. and John Cox, with Dr. Cole serving as Chair of the committee. The Board of Directors has determined that each member of the Compensation Committee is “independent” as defined under the applicable listing standards of Nasdaq and meets the independence criteria set forth in Rule 10C-1 under the Exchange Act. The Compensation Committee’s responsibilities include:

Pursuant to its charter, the Compensation Committee has the authority to delegate any of its responsibilities to subcommittees and has the authority to delegate to the Chief Executive Officer the determination of compensation to employees other than senior officers under approved compensation programs to the maximum extent permitted by applicable law. During the year ended December 31, 2021, the Compensation Committee met four times.

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Compensation Consultant

The Compensation Committee has engaged Pay Governance, as its independent compensation consultant. Pay Governance provides analysis and recommendations to the Compensation Committee regarding:

When requested, Pay Governance consultants attend meetings of the Compensation Committee, including executive sessions in which executive compensation related matters are discussed without the presence of management. Pay Governance reports to the Compensation Committee and not to management, although Pay Governance meets with management for purposes of gathering information for its analyses and recommendations.

In determining to engage Pay Governance, the Compensation Committee considered the independence of Pay Governance, taking into consideration relevant factors, including the absence of other services provided to the Company by Pay Governance, the amount of fees the Company paid to Pay Governance as a percentage of Pay Governance’s total revenue, the policies and procedures of Pay Governance that are designed to prevent conflicts of interest, any business or personal relationship of the individual compensation advisors employed by Pay Governance with any executive officer of the Company, any business or personal relationship the individual compensation advisors employed by Pay Governance have with any member of the Compensation Committee, and any stock of the Company owned by Pay Governance or the individual compensation advisors employed by Pay Governance. The Compensation Committee has determined, based on its analysis and in light of all relevant factors, including the factors listed above, that the work of Pay Governance and the individual compensation advisors employed by Pay Governance as compensation consultants to the Compensation Committee has not created any conflicts of interest, and that Pay Governance is independent pursuant to the independence standards set forth in the Nasdaq listing standards promulgated pursuant to Section 10C of the Exchange Act.

Code of Business Conduct and Ethics

We have adopted a Code of Business Conduct and Ethics for our directors, officers and employees, including our Chief Executive Officer and President and our Chief Financial Officer. A copy of our Code of Business Conduct and Ethics may be accessed free of charge by visiting our website at www.sigilon.com and going to the “Corporate Governance” tab under the “Investors/Media” section, or by requesting a copy in writing from our Secretary at our Cambridge, Massachusetts office. We intend to post on our website any amendment to, or waiver under, a provision of the Code of Business Conduct and Ethics that applies to our directors and certain of our executive officers within four business days following the date of such amendment or waiver.

A copy of the Corporate Governance Guidelines may also be accessed free of charge by visiting the website at www.sigilon.com and going to the “Corporate Governance” tab under the “Investors/Media” section, or by requesting a copy in writing from our Secretary at our Cambridge, Massachusetts office.

Policy Against Hedging Stock

Our insider trading policy prohibits our directors, officers and employees from entering into hedging or monetization transactions, including through the use of financial instruments such as prepaid variable forwards, equity swaps, collars and exchange funds, because such transactions may permit a director, officer or employee to continue to own securities obtained through our employee benefit plans or otherwise, but without the full risks and rewards of ownership. When that occurs, the individual may no longer have the same objectives as our other shareholders.

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EXECUTIVE OFFICER BIOGRAPHIES

Rogerio Vivaldi Coelho, M.D.’s biography is included under “Director Biographies” above.

Philip Asthon-Rickardt, Ph.D., has served as our Chief Scientific Officer since 2021. Previously, Dr. Ashton-Rickardt served as Senior Vice President for Immunology at AZTherapies, Inc., where he was responsible for preclinical development of cell therapies, biologic and small molecule platform technologies to treat neurodegenerative diseases. Dr. Ashton-Rickardt joined AZTherapies in 2019 in connection with its acquisition of Smith Therapeutics, a private company founded by Dr. Ashton-Rickardt to develop a cutting-edge technology platform that he invented using modified T cells to restore a healthy balance of inflammatory and regulatory cells in the brain. Prior to launching Smith Therapeutics in 2017, Dr. Ashton-Rickardt was Chair in Immunology at Imperial College London, Visiting Professor, Brigham and Women’s Hospital, Harvard Medical School, and Associate Professor in the Department of Pathology at the University of Chicago. His work has been recognized by his peers through the award of tenure from The University of Chicago and by his fellow citizens as a recipient of the Early Career Award for Scientists and Engineers from President Bill Clinton. He has published more than 65 peer-reviewed papers in more than 30 academic journals (including Cell, Science, Immunity, and Nature Immunology), has served as an editor for several academic journals, and has been a member of grant review boards globally. Dr. Ashton-Rickardt earned a B.Sc. in Biochemistry from the University of London, King’s College and a Ph.D. in Molecular Biology from the University of Edinburgh.

May Orfali, M.D., brings more than 25 years of expertise in clinical development and medical affairs to her role as Chief Medical Officer at Sigilon. Prior to joining Sigilon, from 2018 to 2021, Dr. Orfali served as President at Rare Disease & Oncology Consulting, LLC, where she assisted a number of life science companies and worked closely with the clinical and medical affairs teams. Prior to that, in 2018, she was the Chief Medical Officer at CANbridge Life Sciences where she led the clinical development and medical affairs group, focused on progressing Phase 1 and Phase 2 oncology assets in glioblastoma multiforme and esophageal cancer, filing NDA for neratinib in China in adjuvant and metastatic breast cancer therapy, in addition to leading medical review of business development opportunities in rare disease space. Prior to that, she served in roles of increasing responsibility at Pfizer, Inc. for a period of more than eight years. During her tenure Dr. Orfali was responsible for patient-focused drug development across multiple rare disease assets in hematology, sickle cell disease, hemophilia, endocrinology, gene therapy and TTR-amyloidosis. She also held clinical leadership positions at Wyeth Pharmaceutical Company, Artisan Pharma, Inc., Aeris Therapeutics, and Women’s Health Group at Boston Scientific Corporation. Dr. Orfali holds a medical degree from the University of Baghdad and a Pharmaceutical Master of Business Administration from Cambridge University. She completed her Fellowship in Pediatric Oncology/Hematology at Massachusetts General Hospital and Children’s Hospital and practiced medicine and conducted clinical research in medical oncology at Dana Farber Cancer research Institute.

Josias Pontes has served as the Company’s Senior Vice President, Acting Chief Financial Officer and Treasurer since February 2022 and previously served as the Company's Vice President, Head of Finance since November 2019. Prior to joining the Company, Mr. Pontes was Senior Director, Financial Planning and Analysis at Zafgen, Inc., a biotechnology company, from December 2017 to August 2019. From 2016 to 2018, Mr. Pontes served as Senior Director, Accounting Reporting and Consolidation and Financial Planning and Analysis at Juniper Pharmaceuticals, Inc.

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Mr. Pontes also worked in various finance roles of increasing responsibility at Genzyme, most recently serving as the Senior Director of Finance and Controller of the Rare Diseases business unit. He holds an M.B.A. from Ohio University and a B.A. in Accounting from the FECAP University in Sao Paulo, Brazil.

Qing Sarah Yuan, Ph.D., has served as the Company’s Chief Technical Operations Officer since March 2022. Dr. Yuan brings more than 20 years of experience in process development, manufacturing sciences and CMC strategies from a broad range of leading biopharmaceutical companies. Prior to joining Sigilon, from November 2021 to March 2022, Dr. Yuan served as Vice President of Process and Analytical Development at 2seventy bio, the oncology spinoff of bluebird bio, Inc. From July 2019 to November 2021, she held a similar role at bluebird bio. Prior to that, Dr. Yuan led the External Manufacturing Organization for the Rare Blood Disorders Franchise at Sanofi for a period of four months following its acquisition of Bioverativ. From 2017 to 2019, she served as the Head of Technical Development and Manufacturing Sciences at Bioverativ. Earlier in her career, Dr. Yuan held various roles with increasing responsibilities in Biogen’s Manufacturing Sciences department, led Process Development at Agenus, and spent several years developing novel resins and membranes at Millipore. She holds a Ph.D. in Chemical Engineering from University of Wisconsin, Madison, and a B.S. in Chemical Engineering from University of California at Berkeley.

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Summary compensation table

The following table sets forth the compensation awarded to, earned by, or paid to our named executive officers in respect of their service to us for the fiscal years ended December 31, 2021 and December 31, 2020:

Overview

Our executive compensation program is designed to attract, retain and reward key employees, to incentivize them to achieve key performance goals, and to align their interests with the interests of our shareholders. The Compensation Committee is generally responsible for determining the compensation of our executive officers. Our Chief

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Executive Officer made recommendations to the Compensation Committee about the compensation of his direct reports in respect of fiscal year 2021, including the named executive officers (other than himself).

In 2021, the Compensation Committee engaged Pay Governance, an independent compensation consulting firm, to assist it in evaluating the Company’s executive and director compensation practices, including program design, identification of an appropriate peer group for compensation comparison purposes and providing pay benchmarking data. Prior to engaging Pay Governance, the Compensation Committee assessed the independence of Pay Governance from management and, on the basis of that assessment and taking into consideration the independence factors that are required to be considered under applicable stock exchange rules, satisfied itself that no relationships exist that would create a conflict of interest or that would compromise Pay Governance’s independence.

2021 Base salary and annual bonus

The letter agreement with each named executive officer, described below, establishes a base salary for such officer, which was determined at the time that the named executive officer commenced employment with us. For fiscal year 2021, the base salary for each of Drs. Vivaldi, Ashton-Rickardt, Orfali, Corzo and Smith was $578,200, $400,000, $475,000, $431,550 and $443,975 respectively.

With respect to fiscal year 2021, each of Drs. Vivaldi, Ashton-Rickardt, Corzo and Smith was eligible to receive an annual bonus, with the target amount of such bonus for each named executive officer initially set forth in his letter agreement with us, described below. For fiscal year 2021, the target bonus amounts, expressed as a percentage of base salary, for each of Drs. Vivaldi, Ashton-Rickardt, Corzo and Smith were as follows: 55%, 40%, 40% and 40%, respectively. Annual bonuses for fiscal year 2021 for our named executive officers were based on the attainment of corporate performance goals as determined by the Compensation Committee. The corporate performance goals for 2021 were generally related to clinical, regulatory, pipeline, platform, financing and business development objectives of the Company. For 2021, the corporate performance goals were partially met resulting in a corporate performance score of 50% of target. Each named executive officer who was employed with us on December 31, 2021 and eligible to receive an annual bonus received a 2021 annual bonus as follows: Dr. Vivaldi, $159,005 and Dr. Ashton-Rickardt, $44,055 (pro-rated to reflect Dr. Ashton-Rickardt’s partial year of employment with us). Dr. Orfali, who commenced employment with us in November 2021, was not eligible for a 2021 annual bonus.

Agreements with our named executive officers

Each of our named executive officers is party to a letter agreement with us that sets forth the terms and conditions of his employment with us. The material terms of the agreements are described below.

Dr. Vivaldi. We entered into a letter agreement with Dr. Vivaldi that provides for an initial base salary of $500,000 per year and a target annual bonus equal to 50% of his annual base salary (each of which has subsequently been increased), with the actual amount of the bonus earned determined by the Board of Directors or the Compensation Committee based on the achievement of specific milestones or performance criteria established by the Board of Directors or the Compensation Committee.

Dr. Vivaldi also entered into an Employee Non-Competition, Non-Solicitation, Confidentiality and Assignment Agreement under which he has agreed not to compete with us or solicit our employees, consultants, customers or suppliers during employment and for one year following his termination of employment and has agreed to a perpetual confidentiality covenant and an assignment of intellectual property covenant.

Dr. Ashton-Rickardt. We entered into a letter agreement with Dr. Ashton-Rickardt that provides for an initial base salary of $400,000 per year and a target annual bonus equal to 40% of his annual base salary, with the actual amount of the bonus earned determined by the Board of Directors or the Compensation Committee based on the achievement of specific milestones or performance criteria established by the Board of Directors or the Compensation Committee.

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Dr. Ashton-Rickardt also entered into an Employee Non-Solicitation, Confidentiality and Assignment Agreement and an Employee Non-Competition Agreement under which he has agreed not to compete with us or solicit our employees, consultants, customers or suppliers during employment and for one year following his termination of employment and has agreed to a perpetual confidentiality covenant and an assignment of intellectual property covenant.

Dr. Orfali. We entered into a letter agreement with Dr. Orfali that provides for an initial base salary of $475,000 per year and a target annual bonus equal to 40% of her annual base salary, with the actual amount of the bonus determined by the Board of Directors or the Compensation Committee based on the achievement of specific milestones or performance criteria established by the Board of Directors or the Compensation Committee.

Dr. Orfali also entered into an Employee Non-Solicitation, Confidentiality and Assignment Agreement and an Employee Non-Competition Agreement under which she has agreed not to compete with us or solicit our employees, consultants, customers or suppliers during employment and for one year following her termination of employment and has agreed to a perpetual confidentiality covenant and an assignment of intellectual property covenant.

Prior to the commencement of her employment with us in November 2021, Dr. Orfali was party to a consulting agreement with us pursuant to which she received a fee of $400 per hour for consulting and advisory services related to the clinical development and regulatory path of our product candidates.

Dr. Corzo. Prior to her termination of employment, we had been party to a letter agreement with Dr. Corzo that provided for an initial base salary of $330,000 per year and a target annual bonus equal to 30% of her annual base salary (each of which has subsequently been increased), with the actual amount of the bonus earned determined by the Board of Directors or the Compensation Committee based on the achievement of specific milestones or performance criteria established by the Board of Directors or the Compensation Committee.

In connection with her termination of employment, Dr. Corzo entered into a separation agreement pursuant to which she received three months’ base salary continuation and payment of COBRA premiums through December 31, 2021. All unvested equity awards held by Dr. Corzo as of the termination of her employment were terminated as of that date.

Dr. Smith. Prior to his termination of employment, we had been party to a letter agreement with Dr. Smith that provided for an initial base salary of $300,000 per year and a target annual bonus of 30% of his annual base salary (each of which was subsequently increased), with the actual amount of the bonus earned determined by the Board of Directors or the Compensation Committee based on the achievement of specific milestones or performance criteria established by the Board of Directors or the Compensation Committee.

Dr. Smith also entered into an Employee Non-Competition, Non-Solicitation, Confidentiality and Assignment Agreement under which he has agreed not to compete with us or solicit our employees, consultants, customers or suppliers during employment and for one year following his termination of employment and has agreed to a perpetual confidentiality covenant and an assignment of intellectual property covenant.

Dr. Smith did not receive any severance payments or benefits in connection with the termination of his employment. We entered into a consulting agreement with Dr. Smith, effective April 26, 2021, pursuant to which he agreed to provide certain transition-related services to us through May 31, 2021. The consulting agreement provided for a consulting fee of $100 per hour and for continued vesting of Dr. Smith’s unvested options through May 31, 2021. Upon the termination of the consulting agreement, all unvested equity awards held by Dr. Smith were terminated. Dr. Smith’s consulting agreement also contains a perpetual confidentiality covenant and an assignment of intellectual property covenant.

Severance and change of control payments and benefits

In lieu of any severance benefits provided under our letter agreements with our named executive officers, each of our named executive officers is entitled to receive severance benefits under our Severance and Change in Control

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Policy, as amended. The terms “cause,” “good reason” and “change in control” referred to below are defined in our Severance and Change in Control Policy.

Dr. Vivaldi. If Dr. Vivaldi’s employment is terminated by us without cause outside of a change in control, he will be entitled to receive (i) continued payment of his then-current base salary for a period of 12 months following termination and (ii) payment of COBRA premiums following his termination for up to 12 months, or, if earlier, until the date on which Dr. Vivaldi’s COBRA coverage terminates or he ceases to be eligible for such coverage for any reason (including upon becoming eligible for coverage under a subsequent employer’s medical plan), subject to his eligibility for, and timely election of, COBRA coverage.

If Dr. Vivaldi’s employment is terminated by us without cause or by him for good reason upon or within 12 months following a change in control, he will be entitled to receive (i) continued payment of his then-current base salary for a period of 18 months following termination, (ii) payment of COBRA premiums following his termination for up to 18 months, or, if earlier, until the date on which Dr. Vivaldi’s COBRA coverage terminates or he ceases to be eligible for such coverage for any reason (including upon becoming eligible for coverage under a subsequent employer’s medical plan), subject to his eligibility for, and timely election of, COBRA coverage, (iii) 150% of his target annual bonus for the year of termination and (iv) full acceleration of vesting and exercisability of any unvested equity awards, with outstanding stock options remaining outstanding and exercisable for the remainder of their full term.

Dr. Ashton-Rickardt. If Dr. Ashton-Rickardt’s employment is terminated by us without cause outside of a change in control, he will be entitled to receive (i) continued payment of his then-current base salary for a period of nine months following termination and (ii) payment of COBRA premiums following his termination for up to nine months, or, if earlier, until the date on which Dr. Ashton-Rickardt’s COBRA coverage terminates or he ceases to be eligible for such coverage for any reason (including upon becoming eligible for coverage under a subsequent employer’s medical plan), subject to his eligibility for, and timely election of, COBRA coverage.

If Dr. Ashton-Rickardt’s employment is terminated by us without cause or by him for good reason upon or within 12 months following a change in control, in addition to the severance benefits described above, Dr. Ashton-Rickardt will be entitled to receive (i) 75% of his target annual bonus for the year of termination and (ii) full acceleration of vesting and exercisability of any unvested equity awards, with outstanding stock options remaining outstanding and exercisable for the remainder of their full term.

Dr. Orfali. If Dr. Orfali’s employment is terminated by us without cause outside of a change in control, she will be entitled to receive (i) continued payment of her then-current base salary for a period of nine months following termination and (ii) payment of COBRA premiums following her termination for up to nine months, or, if earlier, until the date on which Dr. Orfali’s COBRA coverage terminates or she ceases to be eligible for such coverage for any reason (including upon becoming eligible for coverage under a subsequent employer’s medical plan), subject to her eligibility for, and timely election of, COBRA coverage.

If Dr. Orfali’s employment is terminated by us without cause or by her for good reason upon or within 12 months following a change in control, in addition to the severance benefits described above, Dr. Orfali will be entitled to receive (i) 75% of her target annual bonus for the year of termination and (ii) full acceleration of vesting and exercisability of any unvested equity awards, with outstanding stock options remaining outstanding and exercisable for the remainder of their full term.

Severance Subject to Compliance with Restrictive Covenant Obligations and Release of Claims. Our obligation to provide a named executive officer with severance payments and other benefits under our Severance and Change in Control Policy is conditioned on (i) the executive signing a release of claims in favor of us, and (ii) the executive’s continued compliance with any restrictive covenant obligations, including any non-competition, non-solicitation and confidentiality obligations.

Section 280G of the Code. Our Severance and Change in Control Policy provides for a Section 280G “better-of provision” such that payments or benefits that each or our named executive officers receives in connection with a change

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in control will be reduced to the extent necessary to avoid the imposition of any excise tax under Sections 280G and 4999 of the Code if such reduction would result in greater after-tax payment amount for such named executive officer.

Employee and retirement benefits

We currently provide broad-based health and welfare benefits that are available to our full-time employees, including our named executive officers, including health, life, disability, vision, and dental insurance. In addition, we maintain a 401(k) retirement plan for our full-time employees. The Company makes matching contributions to our 401(k) plan at a rate of 100% of employee deferrals up to a maximum matching contribution of 3% of eligible compensation. Other than the 401(k) plan, we do not provide any qualified or non-qualified retirement or deferred compensation benefits to our employees, including our named executive officers.

Equity compensation

Each of our named executive officers received incentive equity grants in fiscal year 2021 under our 2020 Equity Incentive Plan, or our 2020 Plan.

On February 11, 2021, Dr. Vivaldi was granted an option to purchase 200,000 shares of our common stock, which vested as to 25% of the underlying shares on February 11, 2022 and vests as to 6.25% of the underlying shares on the first day of each quarter following such date for the subsequent 12 calendar quarters, generally subject to Dr. Vivaldi’s continued employment with us through the applicable vesting date. On November 4, 2021, Dr. Vivaldi was granted 50,000 restricted stock units, which vest as to 20% of the restricted stock units on the first anniversary of the date of grant, 20% of the restricted stock units on the second anniversary of the date of grant, and 60% of the restricted stock units on the third anniversary of the date of grant, generally subject to Dr. Vivaldi’s continued employment with us through the applicable vesting date.

In connection with the commencement of his employment, on July 1, 2021, Dr. Ashton-Rickardt was granted an option to purchase 90,000 shares of our common stock, which vests as to 25% of the underlying shares on June 14, 2022 and vests as to 6.25% of the underlying shares on the first day of each quarter following such date for the subsequent 12 calendar quarters, generally subject to Dr. Ashton-Rickardt’s continued employment with us through the applicable vesting date.

In connection with the commencement of her employment, on December 1, 2021, Dr. Orfali was granted an option to purchase 80,000 shares of our common stock, which vests as to 25% of the underlying shares on November 29, 2022 and vests as to 6.25% of the underlying shares on the first day of each quarter following such date for the subsequent 12 calendar quarters, generally subject to Dr. Orfali’s continued employment with us through the applicable vesting date.

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Outstanding awards at fiscal year-end table

The following table sets forth information concerning outstanding equity awards held by each of our named executive officers as of December 31, 2021:

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Director compensation

The following table sets forth information concerning the compensation awarded to, earned by or paid to our non-employee directors during the fiscal year ended December 31, 2021. Dr. Vivaldi’s compensation for 2021 is included with that of our other named executive officers above.

Director compensation

Upon her initial appointment to our board of directors, and prior to the effectiveness of our director compensation policy, described below, Ms. Story received an option to purchase 17,777 shares of our common stock, which vests as to 25% of the underlying shares on the first anniversary of the grant date, and as to 6.25% of the underlying shares on the first day of each quarter following such date for the subsequent 12 calendar quarters, generally subject to Ms. Story’s continued service on our board of directors through the applicable vesting date.

Prior to our initial public offering, Dr. Anderson was party to a consulting agreement with us that set forth the terms and conditions of his consulting services and service on our board of directors. Dr. Anderson’s consulting agreement was terminated in connection with our initial public offering. Following the initial public offering, Dr. Anderson receives compensation as a non-employee director pursuant to our non-employee director compensation policy, described below. We entered into an amended consulting agreement with Dr. Anderson’s wholly-owned corporation, effective June 25, 2021, which provides for fees of $15,000 per quarter in respect of his consulting services

Director compensation policy

Under our director compensation policy, each non-employee director is eligible to receive compensation for his or her service on our board of directors. Each non-employee director is eligible to receive an annual cash retainer, pro-rated to reflect any partial year of service, as set forth in the table below. In addition, each non-employee director who is first elected or appointed to our board of directors in a calendar year will be granted an option under our 2020 Plan to purchase 17,777 shares of our common stock (but in no event will a non-employee director’s initial grant have a grant date fair value, determined in accordance with FASB ASC 718, that exceeds $600,000) upon his or her initial election to our board of directors. Each non-employee director who has served as a member of our board of directors for at least a

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six-month period prior to the first meeting of our board of directors following the annual meeting of our stockholders will annually be granted an option under our 2020 Plan to purchase 8,888 shares of our common stock (but in no event will a non-employee director’s annual grant have a grant date fair value, determined in accordance with FASB ASC 718, that exceeds $300,000).

The stock option granted to a non-employee director upon his or her initial election to our board of directors will vest as to one-third of the underlying shares on each of the first three anniversaries of the date of grant, subject to such director’s continued service on our board of directors. The annual stock options granted to our non-employee directors will vest in full on the first anniversary of the date of grant, subject to the director’s continued service on our board of directors. Upon a change in control (as defined in our 2020 Plan (or as such term or similar term is defined in any successor plan)), each initial stock option and each annual stock option that is then outstanding will vest in full, subject to the director’s continued service on our board of directors through such change in control.

A schedule of board of directors and committee fees applicable in 2021, following our initial public offering, is below.

All cash fees are paid quarterly, in arrears, or upon the earlier resignation or removal of the non-employee director. The amount of each payment will be prorated for any portion of a calendar quarter that a non-employee director is not serving on our board of directors, based on the number of calendar days served by such non-employee director.

Each non-employee director is entitled to reimbursement for reasonable travel and other expenses incurred in connection with attending meetings of our board of directors and any committee on which he or she serves.

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exercise of outstanding options and 275,400 shares of our common stock issuable upon vesting of outstanding restricted stock units under the Sigilon Therapeutics, Inc. 2020 Equity Incentive Plan.

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Eric Shaff, Chair

Stephen Oesterle, M.D.

Brooke Story

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whether the transaction is on terms comparable to those that could be obtained in an arm’s length transaction and the extent of the related person’s interest in the transaction. With the exception of the share space arrangements described above, which were approved in accordance with this policy, all of the transactions described in this section occurred prior to the adoption of this policy.

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We expect that a representative of PwC will attend the Annual Meeting and the representative will have an opportunity to make a statement if he or she so chooses. The representative will also be available to respond to appropriate questions from stockholders.

Policy on Audit Committee Pre-Approval of Audit and Permissible Non-Audit Services of Independent Registered Public Accounting Firm

The Audit Committee pre-approves all auditing services, internal control related services and permitted non-audit services (including the fees and terms thereof) to be performed by PwC, subject to the de minimis exception for non-audit services that are approved by the Audit Committee prior to the completion of an audit. The Audit Committee may delegate pre-approval authority to one or more members of the Audit Committee consistent with applicable law and listing standards, provided that the decisions of such Audit Committee member or members must be presented to the full Audit Committee at its next scheduled meeting. The Audit Committee is responsible for the audit fee negotiations associated with our retention of PwC.

Audit Fees. Audit fees consist of fees billed for professional services provided in connection with the audit of our annual financial statements, the review of our quarterly financial statements, and audit services that are normally provided by independent registered public accounting firm in connection with regulatory filings. The audit fees also include fees for professional services provided in connection with our initial public offering, incurred during the fiscal year ended December 31, 2020, including comfort letters, consents and review of documents filed with the SEC.

Audit-Related Fees. Consist of aggregate fees for accounting consultations and other services that were reasonably related to the performance of audits or reviews of our consolidated financial statements and were not reported above under “Audit Fees.”

Tax Fees. Consist of aggregate fees for tax compliance, tax advice and tax planning services including the review and preparation of our federal and state income tax returns.

All Other Fees. All other fees represent payment for access to PricewaterhouseCoopers LLP online software tools. These fees were approved by the Audit Committee.

The Audit Committee pre-approved all services performed since the pre-approval policy was adopted.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT YOU VOTE “FOR” THE RATIFICATION OF THE SELECTION OF PRICEWATERHOUSECOOPERS LLP AS THE COMPANY’S INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM, AND PROXIES SOLICITED BY THE BOARD WILL BE VOTED IN FAVOR OF SUCH RATIFICATION UNLESS A STOCKHOLDER HAS INDICATED OTHERWISE ON THE PROXY.

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GENERAL MATTERS

Availability of Certain Documents

A copy of our 2021 Annual Report on Form 10-K has been posted on the Internet along with this proxy statement. Upon written request, we will mail, without charge, a copy of our 2021 Annual Report on Form 10-K excluding exhibits. Please send a written request to our Corporate Secretary at:

Sigilon Therapeutics, Inc.

100 Binney Street, Suite 600

Cambridge, MA 02142

Attention: Secretary

Phone: (617) 336-7540

SEC rules concerning the delivery of annual disclosure documents allow us or your broker to send a single Notice of Proxy Materials 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, unless we have received contrary instructions from one or more of the stockholders. 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 of Proxy Materials, annual reports, proxy statements and information statements.

We will undertake to deliver promptly, upon written or oral request, a separate copy to a stockholder at a shared address to which a single copy of the Notice of Proxy Materials or proxy materials was delivered. You may make a written or oral request by sending a notification to our Secretary at the address or telephone number above, providing your name, your shared address, and the address to which we should direct the additional copy of the Notice of Proxy Materials or proxy materials. Multiple stockholders sharing an address who have received one copy of a mailing and would prefer us to mail each stockholder a separate copy of future mailings should contact us at our principal executive offices. Additionally, if current stockholders with a shared address received multiple copies of a mailing and would prefer us to mail one copy of future mailings to stockholders at the shared address, notification of that request may also be made through our principal executive offices. Stockholders who participate in householding will continue to have access to and utilize separate proxy voting instructions.

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Contacting the Board of Directors

Stockholders wishing to communicate with the Board of Directors may do so by writing to the Board or to the non-employee members of the Board as a group, at:

Sigilon Therapeutics, Inc.

100 Binney Street, Suite 600

Cambridge, MA 02142

Attention: Secretary

The communication must prominently display the legend “BOARD COMMUNICATION” in order to indicate to the Secretary that it is a communication for the Board. Upon receiving such a communication, the Secretary will promptly forward the communication to the relevant individual or group to which it is addressed. Certain items that are unrelated to the Board’s duties and responsibilities may be excluded, such as spam, junk mail and mass mailings, resumes and other forms of job inquiries, surveys and business solicitations or advertisements. The Secretary will not forward any communication determined in his good faith belief to be frivolous, unduly hostile, threatening, illegal or similarly unsuitable.

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