Table of Contents

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.  )

​

​

​

​

Table of Contents

April 26, 2022

Dear Shareholder:

You are cordially invited to attend the 2022 Annual Meeting of Shareholders of ImmunoGen, Inc. (“Annual Meeting”) to be held on Wednesday, June 15, 2022, beginning at 9:00 a.m., Eastern Time, in a virtual-only meeting format.

The accompanying Notice of Annual Meeting of Shareholders and proxy statement describe the matters that will be presented at our Annual Meeting. The agenda for the meeting includes proposals to fix the number of members of our Board of Directors at nine, to elect nine members to our Board of Directors, to amend our Restated Articles of Organization to increase the number of authorized shares of our common stock, to increase the number of shares issuable pursuant to our 2018 Employee, Director and Consultant Equity Incentive Plan (the “2018 Plan”), to hold an advisory vote on executive compensation, and to ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm for the year ending December 31, 2022. The Board of Directors recommends that you vote FOR its proposal to fix the number of members of our Board of Directors at nine, FOR the election of its slate of directors, FOR the proposed increase in the number of authorized shares of our common stock, FOR the proposed increase in the number of shares issuable under our 2018 Plan, FOR approval of the compensation of our named executive officers as disclosed in the proxy statement, and FOR the ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm.

Please refer to the proxy statement for detailed information on each of the proposals. Your vote is important. Whether or not you expect to attend the virtual meeting, your shares should be represented. Therefore, we urge you to vote promptly to ensure that your shares are represented at the Annual Meeting and in accordance with the instructions set forth in either the Notice Regarding the Availability of Proxy Materials or the proxy card that you received. This will ensure your proper representation at our Annual Meeting.

​

YOUR VOTE IS IMPORTANT. PLEASE RETURN YOUR PROXY PROMPTLY.

​

​

​

​

​

​

​

​

Table of Contents

Table of Contents

TABLE OF CONTENTS

​

​

​

​

Table of Contents

830 Winter Street

Waltham, MA 02451

Table of Contents

of these materials, you may complete, sign, and return the accompanying proxy card or submit your proxy by telephone as described below in order to have your shares voted at the meeting on your behalf.

Why did I receive a notice in the mail regarding the internet availability of proxy materials instead of a full set of proxy materials?

As permitted by the rules of the U.S. Securities and Exchange Commission (the “SEC”), we may furnish our proxy materials to our shareholders by providing access to such documents on the Internet, rather than mailing printed copies of these materials to each shareholder. Most shareholders will not receive printed copies of the proxy materials unless they request them. We believe that this process should lower the costs of the annual meeting and help to conserve natural resources. If you received the Notice by mail or electronically, you will not receive a printed or email copy of the proxy materials unless you request one by following the instructions included in the Notice. Instead, the Notice instructs you as to how you may access and review all of the proxy materials and submit your proxy on the Internet. If you requested a paper copy of the proxy materials, you may authorize the voting of your shares by following the instructions on the proxy card.

What am I voting on?

There are six matters scheduled for a vote:

Who can attend and vote at the meeting?

Shareholders of record at the close of business on April 8, 2022 are entitled to attend and vote at the meeting. Each share of our common stock is entitled to one vote on all matters to be voted on at the meeting and can be voted only if the record owner is present to vote or is represented by proxy.

What constitutes a quorum at the meeting?

The presence at the meeting, virtually or represented by proxy, of the holders of a majority of our common stock outstanding on April 8, 2022, the record date, will constitute a quorum for purposes of the meeting. On the record date, 220,536,032 shares of our common stock were outstanding. For purposes of determining whether a quorum exists, proxies received but marked “abstain” and so-called “broker non-votes” (described below) will be counted as present.

How many votes do I have?

Each share of our common stock that you own entitles you to one vote.

How do I vote by proxy?

Your vote is very important. Whether or not you plan to attend the meeting, we urge you to either:

Table of Contents

Requests for printed copies of the proxy materials should be made no later than June 1, 2022, to ensure that they will be received in time for you to cast your vote on a timely basis. Please note that the Notice is not a proxy card or a ballot, and any attempt to vote your shares by marking and returning the Notice will be ineffective.

If you properly complete and deliver your proxy (whether electronically, by mail, or by telephone) and it is received by 11:59 p.m. Eastern Time on June 14, 2022, your shares will be voted as you direct. If you sign, date, and return a proxy card but do not specify how your shares are to be voted, then your shares will be voted as follows:

If any other matter properly comes before the meeting or at any adjournments or postponements thereof, the person acting as your proxy will vote your shares in his discretion. At present we do not know of any other business that is intended to be brought before or acted upon at the meeting.

How do I vote if my shares are held by my broker?

If your shares are held by your broker in “street name,” you will need to instruct your broker how to vote your shares in the manner provided by your broker. You may also log into the Annual Meeting by entering your 16-digit control number found on your voting instruction form and vote your shares during the meeting.

What discretion does my broker have to vote my shares held in “street name”?

A broker holding your shares in “street name” must vote those shares according to any specific instructions it receives from you. If specific instructions are not received, your broker’s ability to vote your shares in its discretion is dependent on the type of proposal involved. A broker generally may not vote on “non-routine” matters without receiving your specific voting instructions. Although the determination of whether a 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 proposals for the election of directors, the amendment to the 2018 Plan, and the advisory proposal on executive compensation will be considered “non-routine” matters. Accordingly, if such a matter comes before the meeting and you have not specifically instructed your broker how to vote your shares, your shares will not be voted on that matter, giving rise to what is called a “broker non-vote.” Shares represented by broker non-votes will be counted for purposes of determining the existence of a quorum for the transaction of business, but for purposes of determining the number of shares voting on a particular proposal broker non-votes will not be counted as votes cast or shares voting. We expect that the votes on fixing the number of members of our Board of Directors, the amendment to our Restated Articles of Organization, and the ratification of the selection of our independent auditors will be considered “routine” matters, and a broker would therefore be able to vote on these proposals even if it does not receive your specific instructions. As a result, we do not expect any broker non-votes will exist in connection with such proposals.

Can I change my vote after I have already voted?

Yes. You may change your vote at any time before your proxy is exercised. To change your vote, you may:

Your last properly cast vote will be counted. Your attendance at the virtual meeting will not by itself be deemed to revoke a previously delivered proxy.

Table of Contents

If your shares are held in “street name,” you should contact your broker, bank, or other nominee for instructions on changing your vote.

How are votes counted?

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, or final results if available, in a Current Report on Form 8-K within four business days of the Annual Meeting. If final results are unavailable at the time we file the Form 8-K, then we will file an amended report on Form 8-K to disclose the final voting results within four business days after the final voting results are known. 

How is ImmunoGen soliciting proxies?

We bear the cost of preparing, assembling, and mailing the proxy material relating to the solicitation of proxies by the Board of Directors for the meeting, as well as the cost of making such materials available on the Internet. In addition to the use of the mails and the Internet, certain of our officers and regular employees may, without additional compensation, solicit proxies in person, by telephone, or other means of communication. We will also request brokerage houses, custodians, nominees, and fiduciaries to forward copies of the proxy material to those persons for whom they hold shares, and will reimburse those record holders for their reasonable expenses in transmitting this material. In addition, we have engaged The Alliance Advisors, LLC to assist in the solicitation of proxies and provide related advice and informational support for a services fee and reimbursement of customary disbursements that are not expected to exceed $15,000, in the aggregate.

VOTING SECURITIES

The following tables set forth certain information with respect to the beneficial ownership of our common stock as of April 8, 2022 for (a) each shareholder known by us to own beneficially more than 5% of our common stock and (b) each of our directors and director nominees, each of our named executive officers, and all of our directors and executive officers as a group.

Beneficial ownership is determined in accordance with the rules of the SEC and includes voting or investment power with respect to the securities. We deem shares of common stock that may be acquired by an individual or group within 60 days of April 8, 2022 pursuant to the exercise of options or warrants, or the vesting of stock units to be outstanding for the

Table of Contents

purpose of computing the percentage ownership of such individual or group, but those shares are not deemed to be outstanding for the purpose of computing the percentage ownership of any other person shown in the tables. Except as indicated in footnotes to the tables, we believe that the shareholders named in these tables have sole voting and investment power with respect to all shares of common stock shown to be beneficially owned by them based on information provided to us by these shareholders. Percentage of ownership is based on 220,536,032 shares of our common stock outstanding as of April 8, 2022.

Who owns more than 5% of our stock?

To our knowledge, as of April 8, 2022, there were seven shareholders who beneficially owned more than 5% of our common stock. The table below contains information regarding the beneficial ownership of these entities.

Table of Contents

How many shares do ImmunoGen’s directors and executive officers own?

The following information is furnished as of April 8, 2022, with respect to common stock beneficially owned by: (1) our directors (including our chief executive officer); (2) our named executive officers; and (3) all directors and executive officers as a group.

*Unless otherwise indicated, the address is c/o ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451.

**Less than 1.0%.

​

Table of Contents

​

ELECTION OF DIRECTORS

(Proposals 1 and 2)

Who sits on the Board of Directors?

Our by-laws provide that, at each annual meeting of shareholders, our shareholders will fix the number of directors to be elected to our Board of Directors. At our 2021 annual meeting of shareholders, the shareholders voted to fix the number of directors at seven. The Board subsequently fixed the number of directors at nine and our Board of Directors currently consists of nine members. The shareholders may increase or decrease the number of directors constituting the full Board of Directors, provided that such number may not be less than three.

We are proposing that shareholders fix the number of directors to be elected at the meeting at nine. We are nominating the nine directors listed below for election. Persons elected as directors at the meeting will serve in office until the next annual meeting of shareholders and until their successors have been elected and qualified or until they die, resign, or are removed.

Recommendation

The Board recommends a vote “FOR” the proposal fixing the number of directors at nine and “FOR” the election of the nine nominees listed below.

Information About the Director Nominees

The persons named as proxies will vote, unless authority is withheld, for the election of the nominees named below. We have no reason to believe that any of the nominees will be unavailable for election. However, if any one of them becomes unavailable, the persons named as proxies have discretionary authority to vote for a substitute chosen by the Board.

Table of Contents

The names of our director nominees and certain other information about them are set forth below.

Stephen C. McCluski has served as the Chair of our Board of Directors since 2009. Mr. McCluski served as Senior Vice President and Chief Financial Officer of Bausch & Lomb Incorporated, a manufacturer of health care products for the eye, from 1995 to his retirement in 2007. Mr. McCluski is also a director of Monro, Inc.

We believe Mr. McCluski’s qualifications to serve on our Board include his global management experience and knowledge of financial and accounting matters and mergers and acquisitions. As a result of these experiences, Mr. McCluski has a wide-ranging understanding of business organizations generally and healthcare businesses in particular. Mr. McCluski also has significant corporate governance experience through his current and past service on other company boards.

Stuart A. Arbuckle has served as Executive Vice President and Chief Operating Officer of Vertex Pharmaceuticals Incorporated, a pharmaceutical company, since 2020 and previously served as Vertex’s Executive Vice President and Chief Commercial Officer from 2012 to 2020. Prior to that he spent eight years at Amgen Inc., a pharmaceutical company, in multiple commercial leadership roles, including Vice President and General Manager for Amgen’s oncology business unit, where he was responsible for sales, marketing, and patient advocacy and access efforts for Amgen’s portfolio of cancer medicines including Aranesp^® (darbepoetin alfa), Neulasta^® (pegfilgrastim) injection, and NEUPOGEN^® (filgrastim), and led the successful launches of XGEVA^® (denosumab) injection and Nplate^® (romiplostim) injection. He also served as Vice President and Regional General Manager and led efforts to expand Amgen’s presence in Japan, Asia, the Middle East and Africa. Prior to joining Amgen, he spent more than 15 years at GlaxoSmithKline (GSK) plc, a pharmaceutical company, and its predecessors, where he held positions of increasing responsibility in sales and marketing for medicines aimed at treating respiratory, metabolic, musculoskeletal, cardiovascular, and other diseases. Mr. Arbuckle is also a director of Rhythm Pharmaceuticals, Inc. He also serves as a national board member of the Cancer Support Community, an international non-profit dedicated to providing support, education, and hope to people affected by cancer, and on the Executive Committee and Health Section Governing Board for the Biotechnology Innovation Organization (BIO) and serves as co-chair of the BIO Standing Committee on Access & Value. Within the past five years, Mr. Arbuckle also served as a director of Cerulean Pharma Inc. prior to its merger with Daré Bioscience, Inc.

We believe Mr. Arbuckle’s qualifications to serve on our Board include his extensive commercial experience in oncology, commercial manufacturing and supply chain functions, human resources, corporate communications, and portfolio management, as well as in the pharmaceutical industry generally.

Mark J. Enyedy has served as our President and Chief Executive Officer since 2016. Prior to joining ImmunoGen, he served in various executive capacities at Shire PLC, a pharmaceutical company, from 2013 to 2016, including as Executive Vice President and Head of Corporate Development from 2014 to 2016, where he led Shire’s strategy, M&A, and corporate planning functions and provided commercial oversight of Shire’s pre-Phase 3 portfolio. Prior to joining Shire, he served as Chief Executive Officer and a director of Proteostasis Therapeutics, Inc., a biopharmaceutical company, from 2011 to 2013. Prior to joining Proteostasis, he served for 15 years at Genzyme Corporation, a biopharmaceutical company, most recently as President of the Transplant, Oncology, and Multiple Sclerosis divisions. Mr. Enyedy holds a JD from Harvard Law School and practiced law prior to joining Genzyme. Mr. Enyedy is also a director of LogicBio Therapeutics, Inc., Ergomed PLC, the Biotechnology Innovation Organization (BIO), and The American Cancer Society of Eastern New England. Within the past five years, he also served as a director of Akebia Therapeutics, Fate Therapeutics, Inc., and Keryx Biopharmaceuticals, Inc.

Table of Contents

We believe that Mr. Enyedy should serve on our Board in recognition of his leadership role as our President and Chief Executive Officer. As a result of his position, Mr. Enyedy has a thorough understanding of all aspects of our business and operations.

Mark Goldberg, M.D., served in various executive capacities of increasing responsibility at Synageva BioPharma Corp., a biopharmaceutical company, from 2011 to 2014, including as Executive Vice President, Medical and Regulatory Strategy from January to October 2014. From October 2014 through the acquisition of Synageva by Alexion Pharmaceuticals, Inc. in 2015, Dr. Goldberg, while no longer an officer, remained employed by Synageva contributing to medical and regulatory strategy. Prior to joining Synageva he served in various management capacities of increasing responsibility at Genzyme Corporation, a biopharmaceutical company, from 1996 to 2011, most recently as Senior Vice President, Clinical Development and Global Therapeutic Head, Oncology, Genetic Health, and as Chair of Genzyme’s Early Product Development Board. Prior to joining Genzyme, he was a full-time staff physician at Brigham and Women’s Hospital and the Dana-Farber Cancer Institute. Dr. Goldberg is also a Lecturer in Medicine (part-time) at Harvard Medical School. From 2015 to 2018, he served as acting chief medical officer of CANbridge Life Sciences Ltd., a biopharmaceutical company. Dr. Goldberg holds a Doctor of Medicine degree from Harvard Medical School. He is also a director of Blueprint Medicines Corporation, GlycoMimetics, Inc., Idera Pharmaceuticals, Inc., Walden Biosciences, Avacta Group plc, and The American Cancer Society. Within the past five years, he also served as a director of aTyr Pharma, Inc. and Audentes Therapeutics, Inc.

We believe that Dr. Goldberg's qualifications to serve on our Board include his comprehensive experiences in clinical research and medical affairs, as well as early-stage research, at his former employers, which give him a wide-ranging understanding of the drug development process for biopharmaceutical products from the research stage through clinical development.

Tracey L. McCain, Esq. has been a director of ImmunoGen since 2021. Since September 2016, Ms. McCain has served as Executive Vice President & Chief Legal and Compliance Officer of Blueprint Medicines Corporation, a commercial-stage global precision therapy company focused on genomically-defined cancers and hematological disorders. Prior to that, from January 2016 to September 2016, Ms. McCain was Senior Vice President and Head of Legal for Sanofi Genzyme, a global business unit of the biopharmaceutical company Sanofi S.A. From May 1997 to January 2016, Ms. McCain held various roles at Genzyme Corporation, a biopharmaceutical company, including as General Counsel following Genzyme’s acquisition by Sanofi in 2011. Prior to joining Genzyme, she was an Associate at Palmer & Dodge LLP. Ms. McCain holds a J.D. from Columbia University School of Law and a B.A. from the University of Pennsylvania. She is also a director of Kiniksa Pharmaceuticals, Ltd.

We believe Ms. McCain is qualified to serve on our Board based on her legal expertise and her experience working with numerous biotechnology and pharmaceutical companies, including serving on the executive team of commercial-stage companies.

Dean J. Mitchell served as Executive Chair of the Board of Covis Pharma Holdings, a specialty pharmaceutical company, from 2013 to 2020, and as Chair of PaxVax Corporation, a specialty vaccine company, from 2016 to 2018. Prior to that, he served as President and Chief Executive Officer of Lux Biosciences, Inc., a biotechnology company focusing on the treatment of ophthalmic diseases, from 2010 to 2013. Prior to that, he served as President and Chief Executive Officer of Alpharma, Inc., a publicly traded human and animal pharmaceutical company, from 2006 until its acquisition by King Pharmaceuticals, Inc. in 2008. Prior to that he served as President and Chief Executive Officer of Guilford Pharmaceuticals, Inc., a publicly traded specialty pharmaceutical company from 2004 until its acquisition by MGI PHARMA, INC. in 2005. Prior to that he served in various senior executive capacities in the worldwide medicines group of Bristol-Myers Squibb Company, a pharmaceutical company, from 2001 to 2004. Prior to that, he spent 14 years at GlaxoSmithKline plc, a pharmaceutical company, in assignments of increasing responsibility spanning sales, marketing, general management, commercial strategy and clinical development and product strategy. Mr. Mitchell is also a director of Precigen (formerly Intrexon, Inc.), Theravance BioPharma, Inc., Kinnate Biopharma Inc., and Praxis Precision Medicines, Inc.

We believe that Mr. Mitchell’s qualifications to serve on our Board include his management experience in the pharmaceutical and biotherapeutics industries, in particular as it relates to later-stage drug development and commercialization, and his experience as a CEO and board member of multiple biotechnology companies.

Kristine Peterson has most recently served as Chief Executive Officer of Valeritas, Inc., a medical technology company focusing on innovative drug delivery systems, from 2009 to 2016. Prior to that she served as Company Group Chair of the biotech groups at Johnson & Johnson, a healthcare products and pharmaceutical company, from 2006 to 2009, and as Executive Vice President for J&J’s global strategic marketing organization from 2004 to 2006. Prior to that she served as

Table of Contents

Senior Vice President, Commercial Operations for Biovail Corporation, a pharmaceutical company, and President of Biovail Pharmaceuticals from 2003 to 2004. Prior to that she spent 20 years at Bristol-Myers Squibb Company, a pharmaceutical company, in assignments of increasing responsibility spanning marketing, sales and general management, including running a cardiovascular/metabolic business unit and a generics division. Ms. Peterson is also a director of Amarin Corporation plc, Enanta Pharmaceuticals, Inc., ImmunoCore, Inc., and Paratek Pharmaceuticals, Inc. and, within the past five years, she also served as a director of Valeritas, Inc. and Eyepoint Pharmaceuticals, Inc.

We believe Ms. Peterson’s qualifications to serve on our Board include her extensive executive management and sales and marketing experience in both mature pharmaceutical and smaller biotechnology companies, in particular as it relates to later-stage development and commercialization, and her other public company board experience.

Helen M. Thackray, M.D. has been a director of ImmunoGen since 2021. Dr. Thackray is the Chief Research and Development Officer for BioCryst Pharmaceuticals, Inc., a commercial-stage biotech company that advances novel therapeutics for patients with rare and serious diseases, a position she has held since 2021. Prior to that, she served in various executive capacities of increasing responsibility at GlycoMimetics, Inc. from 2006 to 2021, including most recently as Chief Medical Officer and Senior Vice President, Clinical Development. She also served in positions of increasing responsibility leading clinical development in rare diseases from 2001 to 2006 at Biosynexus, Inc. From 2000 to 2014, she was a Volunteer Clinician at Children's National Medical Center, in Washington, D.C.; and from 1998 to 1999, she was Chief Resident there. Dr. Thackray is a board-certified pediatrician, and, since 2002, has been an Assistant Clinical Professor in Pediatrics at the George Washington University School of Medicine and Health Sciences. She holds a Doctor of Medicine degree from the George Washington University School of Medicine and Health Sciences. Within the past five years, Dr. Thackray also served as a director of BioCryst Pharmaceuticals.

We believe Dr. Thackray’s qualifications to serve on our Board include her extensive clinical development and executive experience in rare diseases and oncology.

Richard J. Wallace served as a Senior Vice President for Research and Development at GlaxoSmithKline plc (GSK), a pharmaceutical company, from 2004 until his retirement in 2008. Prior to that, he served in various executive capacities for GSK and its predecessor companies and their subsidiaries from 1992 to 2004. Mr. Wallace’s experience prior to joining GSK included eight years with Bristol-Myers Squibb Company, a pharmaceutical company, and seven years at Johnson & Johnson, a healthcare products and pharmaceutical company, in assignments spanning marketing, sales, manufacturing, and general management. Within the past five years, he also served as a director of GNC Holdings, Inc.

We believe Mr. Wallace’s qualifications to serve on our Board include former experience in various capacities of increasing responsibility at several large pharmaceutical companies. As a result of these experiences, Mr. Wallace has a wide-ranging understanding of drug development both in the U.S. and internationally. Mr. Wallace also has significant corporate governance experience through his current and past service on other company boards.

CORPORATE GOVERNANCE

Independence

Our Board of Directors has determined that a majority of the members of the Board should be “independent directors,” determined in accordance with the applicable listing standards of The Nasdaq Stock Market (“Nasdaq”) as in effect from time to time. Directors who are also ImmunoGen employees are not considered to be independent for this purpose. For a non-employee director to be considered independent, he or she must not have any direct or indirect material relationship with ImmunoGen. A material relationship is one which, in the opinion of the Board, would interfere with the exercise of independent judgment in carrying out the responsibilities of a director. In determining whether a material relationship exists, the Board considers the circumstances of any direct compensation received by a director or a member of a director’s immediate family from ImmunoGen; any professional relationship between a director or a member of a director’s immediate family and ImmunoGen’s independent registered public accounting firm; any participation by an ImmunoGen executive officer in the compensation decisions of other companies employing a director or a member of a director’s immediate family as an executive officer; and commercial relationships between ImmunoGen and other entities with which a director is affiliated (as an executive officer, partner, or controlling shareholder). In addition, the Board has determined that directors who serve on the Audit Committee and the Compensation Committee must qualify as independent under applicable SEC rules and Nasdaq listing standards, which limit the compensation a member of the Audit Committee or Compensation Committee may receive directly or indirectly from ImmunoGen and require that Audit Committee members not be “affiliated persons” of ImmunoGen or its subsidiaries. Consistent with these considerations, the Board has determined that all of the current members of the Board are independent directors, except Mr. Enyedy, who is also our chief executive officer.

Table of Contents

How are nominees for the Board selected?

Our Governance and Nominating Committee is responsible for identifying and recommending nominees for election to the Board. The committee will consider nominees recommended by shareholders if the shareholder submits the nomination in compliance with applicable requirements. All of the nominees for director standing for election at the meeting (other than Dr. Thackray and Ms. McCain) were most recently re- elected as directors at our 2021 annual meeting of shareholders.

Director Qualifications

When considering a potential candidate for membership on the Board, the Governance and Nominating Committee examines a candidate’s specific experience, knowledge, skills, expertise, integrity, ability to make independent analytical inquiries, understanding of our business environment, and willingness to devote adequate time and effort to Board responsibilities. In addition to these qualifications, when considering potential candidates for the Board, the committee seeks to ensure that the Board is comprised of a majority of independent directors and that the committees of the Board are comprised entirely of independent directors. The committee may also consider any other standards that it deems appropriate, including whether a potential candidate’s skill and experience would enhance the ability of a particular Board committee to fulfill its duties.

We believe it is important that our Board members collectively bring the experiences and skills appropriate to effectively carry out their responsibilities with respect to our business both as conducted today and as we plan to achieve our longer-term strategic objectives. We therefore seek as members of our Board individuals with a variety of perspectives, racial, ethnic, and gender diversity, and the expertise and ability to provide advice and oversight in the areas of financial and accounting controls; biotechnology research and drug development; business strategy; clinical development and regulatory affairs; compensation practices; product commercialization, including pricing and reimbursement; and corporate governance.

Potential candidates may come to the attention of the Governance and Nominating Committee from current directors, executive officers, shareholders, or other persons. Dr. Thackray and Ms. McCain, who were first elected as a director by the Board on September 22, 2021 and November 15, 2021, respectively, were initially introduced to the Governance and Nominating Committee by a current director. The committee also, from time to time, engages firms that specialize in identifying director candidates. In 2021, the committee engaged a third-party firm to expand the committee’s search for candidates and compile information about potential candidates. Once a person has been identified by the Governance and Nominating Committee as a potential candidate, the committee may collect and review publicly available information regarding the person to assess whether the person should be considered further. If the committee determines that the

Table of Contents

candidate warrants further consideration, and the person expresses a willingness to be considered and to serve on the Board, the committee requests information from the candidate, reviews the person’s accomplishments and qualifications, compares those accomplishments and qualifications to those of any other candidates that the committee might be considering, and conducts one or more interviews with the candidate. In certain instances, members of the committee may contact one or more references provided by the candidate or may contact other members of the business community or other persons that may have greater first-hand knowledge of the candidate’s credentials and accomplishments. The committee’s evaluation process does not vary based on whether a candidate is recommended by a shareholder, although the Board may take into consideration the number of shares held by the recommending shareholder and the length of time that such shares have been held.

Process for Shareholder Recommendations

Shareholders who wish to submit director candidates for consideration by our Governance and Nominating Committee should send such recommendations to our corporate secretary at ImmunoGen’s executive offices not fewer than 120 days prior to the first anniversary of the date on which ImmunoGen’s proxy statement for the prior year’s annual meeting of shareholders was released. Such recommendations must include the following information: (1) the name and address of the shareholder submitting the recommendation, as they appear on our books, and of the beneficial owner on whose behalf the recommendation is being submitted; (2) the class and number of our shares that are owned beneficially and held of record by such shareholder and such beneficial owner, and the period for which such shares have been held; (3) if the recommending shareholder is not a shareholder of record, a statement from the record holder (usually a broker or bank) verifying the holdings of the shareholder (or alternatively, a current Schedule 13D or 13G, or a Form 3, 4, or 5 filed with the SEC), and a statement from the recommending shareholder of the length of time that the shares have been held (if the recommendation is submitted by a group of shareholders, the foregoing information must be submitted for each shareholder in the group); (4) a statement from the shareholder as to whether he or she has a good faith intention to continue to hold the reported shares through the date of our next annual meeting of shareholders; (5) as to each proposed director candidate, all information relating to such person or persons that is required to be disclosed in solicitations of proxies for election of directors pursuant to Regulation 14A under the Securities Exchange Act of 1934, as amended; (6) a description of the qualifications and background of the proposed director candidate that addresses the minimum qualifications and other criteria for Board membership described above; (7) a description of all arrangements or understandings between the proposed director candidate and the shareholder submitting the recommendation; (8) a description of all relationships between the proposed director candidate and any of our competitors, customers, suppliers, or other persons with special interests regarding ImmunoGen; and (9) the consent of each proposed director candidate to be named in the proxy statement and to serve as a director if elected. Shareholders must also submit any other information regarding the proposed director candidate that SEC rules require to be included in a proxy statement relating to the election of directors.

Can I communicate with ImmunoGen’s directors?

Yes. Shareholders who wish to communicate with the Board or with a particular director may send a letter to ImmunoGen, Inc., 830 Winter Street, Waltham, MA 02451, attention: Legal Department. The mailing envelope should contain a clear notation that the enclosed letter is a “Shareholder-Board Communication” or “Shareholder-Director Communication.” All such letters should clearly state whether the intended recipients are all members of the Board, the Chair, or certain specified individual directors. The legal department will make copies of all such letters and circulate them as appropriate to the appropriate director or directors. Items that are unrelated to the duties and responsibilities of our Board may be excluded, such as: junk mail and mass mailings; resumes and other forms of job inquiries; surveys; and solicitations or advertisements. In addition, any material that is unduly hostile, threatening, or illegal in nature may be excluded.

What is the Board’s leadership structure?

We do not have a policy on whether the same person should serve as both the principal executive officer and Chair of the Board or, if the roles are separate, whether the Chair of the Board should be selected from the non-employee directors or should be an employee. Our Board believes that it should have the flexibility to make these determinations in the way that it believes best provides appropriate leadership for ImmunoGen at a given time.

Our Board believes that its current leadership structure, with Mr. Enyedy serving as CEO and Mr. McCluski serving as Chair of the Board, is appropriate for ImmunoGen at this time. We believe that this separation is appropriate since the CEO has overall responsibility for all aspects of our operations and implementation of our strategy, while the Chair of the Board has a greater focus on corporate governance, including leadership of the Board, and he facilitates communication between the CEO and the other members of the Board.

Table of Contents

What is the Board’s role in risk oversight?

Our Board’s role in risk oversight is to oversee the executive management team to assure that the long-term interests of shareholders are being properly served, including understanding and assessing the principal risks associated with our businesses and operations and reviewing options for the mitigation or management of such risks. The Board as a whole is responsible for such risk oversight, but administers certain of its risk oversight functions through the Audit Committee and the Compensation Committee.

The Audit Committee is responsible for the oversight of our accounting and financial reporting processes, including our systems of internal accounting control. In addition, the Audit Committee discusses guidelines and policies governing the process by which executive management and the relevant company departments assess and manage ImmunoGen’s exposure to risk and discuss our major financial risk exposures and the steps management has taken to monitor and control such exposures.

The Compensation Committee evaluates our compensation policies and practices from the perspectives of whether they support organizational objectives and shareholder interests, and whether or not they create incentives for inappropriate risk-taking.

What committees has the Board established?

The Board of Directors has standing Audit, Compensation, and Governance and Nominating Committees. In addition, the Board of Directors has a Clinical Committee, which assists the Board in oversight of the Company’s research and development programs. Each of these committees, except the Clinical Committee, acts under a written charter, copies of which can be found on ImmunoGen’s website at www.immunogen.com on the Investor Information page under “Corporate Governance.”

Each of the Audit, Compensation, and Governance and Nominating Committees is authorized to obtain advice and assistance from independent compensation consultants, outside legal counsel, and other advisors as it deems appropriate, at ImmunoGen’s expense.

Audit Committee

The Audit Committee is comprised of Stephen C. McCluski, Tracey L. McCain, Kristine Peterson, and Richard J. Wallace, with Mr. McCluski as Chair. All members of the Audit Committee qualify as independent under the definitions promulgated by the SEC and Nasdaq. The Audit Committee assists the Board in its oversight of:

The Audit Committee also reviews the qualifications, independence, and performance of our independent registered public accounting firm and pre-approves all audit and non-audit services provided by such firm and its fees. The Audit Committee is directly responsible for the appointment, compensation, retention, and oversight of the work of our independent registered public accounting firm, which reports directly to the Audit Committee. The Audit Committee also is responsible for reviewing and approving related person transactions in accordance with our written related person transaction policy.

Our Board has also determined that Mr. McCluski and Ms. Peterson each qualifies as an “audit committee financial expert” under SEC rules. Please also see the report of the Audit Committee set forth elsewhere in this proxy statement.

Compensation Committee

The Compensation Committee is comprised of Dean Mitchell, Mark Goldberg M.D., and Stuart A. Arbuckle, with Mr. Mitchell as Chair. All members of the Compensation Committee qualify as independent under the definition promulgated by the SEC and Nasdaq. The Compensation Committee is responsible for:

Table of Contents

Additional information concerning the role of the Compensation Committee, and its processes and procedures, is set forth elsewhere in this proxy statement under “Compensation Discussion and Analysis – Process for Setting Executive Compensation.” Please also see the report of the Compensation Committee set forth elsewhere in this proxy statement.

Governance and Nominating Committee

The Governance and Nominating Committee is comprised of Kristine Peterson, Mark Goldberg M.D., Helen Thackray M.D., and Richard J. Wallace, with Ms. Peterson as Chair. All members of the Governance and Nominating Committee qualify as independent under the definition promulgated by the SEC and Nasdaq. The Governance and Nominating Committee is responsible for:

How often did the Board and committees meet during 2021?

Our Board of Directors met or acted by unanimous written consent 11 times during 2021. The Audit, Compensation, and Governance and Nominating Committees met or acted by unanimous written consent seven, 18, and six times, respectively, during 2021. All of the directors attended at least 75% of the meetings of the Board of Directors and committees of the Board on which they served.

Does ImmunoGen have a policy regarding director attendance at annual meetings of the shareholders?

It is the Board’s policy that, absent any unusual circumstances, all director nominees standing for election will attend our annual meeting of shareholders. All of our directors attended our 2021 annual meeting of shareholders.

Table of Contents

Does ImmunoGen have a Code of Corporate Conduct?

Yes. We have adopted a Code of Corporate Conduct applicable to our officers, directors, and employees. The code is posted on our website at www.immunogen.com on the Investors & Media page under “Corporate Governance.” We intend to satisfy our disclosure requirements regarding any amendment to, or waiver of, a provision of our Code of Corporate Conduct by disclosing such matters on our website. Shareholders may request copies of our Code of Corporate Conduct free of charge by writing to ImmunoGen, Inc., 830 Winter Street, Waltham, MA 02451, attention: Legal Department.

Does ImmunoGen have a written policy governing related person transactions?

Yes. We have adopted a written policy that provides for the review and approval by the Audit Committee of transactions involving ImmunoGen in which a related person is known to have a direct or indirect interest and that are required to be reported under Item 404(a) of Regulation S-K promulgated by the SEC. For purposes of this policy, a related person includes: (1) any of our directors, director nominees, or executive officers; (2) any known beneficial owner of more than 5% of any class of our voting securities; or (3) any immediate family member of any of the foregoing. In situations where it is impractical to wait until the next regularly scheduled meeting of the Audit Committee or to convene a special meeting of the Audit Committee, the Chair of the Audit Committee has been delegated authority to review and approve related person transactions. Transactions subject to this policy may be pursued only if the Audit Committee (or the Chair of the Audit Committee acting pursuant to delegated authority) determines in good faith that, based on all the facts and circumstances available, the transactions are in, or are not inconsistent with, the best interests of ImmunoGen and its shareholders. Other than as described below, there have been no related party transactions since January 1, 2021.

In August of 2021, we entered into a Securities Purchase Agreement (the “Securities Purchase Agreement”) with RA Capital Healthcare Fund, L.P., a beneficial owner of more than 5% of our common stock, to sell a pre-funded warrant to purchase up to 5,434,782 shares of our common stock, for aggregate consideration of $29,945,648.82. The transaction was approved by the Audit Committee in accordance with the terms of our related person transaction policy.

Does ImmunoGen have a written policy prohibiting certain transactions in its shares, such as hedging transactions?

Yes. Such policy is described elsewhere in this proxy statement under “Compensation Discussion and Analysis – Additional Compensation Policies and Practices.”

Does ImmunoGen have a clawback policy related to executive compensation?

Yes. Such policy is described elsewhere in this proxy statement under “Compensation Discussion and Analysis – Additional Compensation Policies and Practices.”

ENVIRONMENTAL, SOCIAL, AND GOVERNANCE

Our mission is to develop the next-generation of antibody-drug conjugates to improve outcomes for cancer patients. By delivering targeted therapies with improved anti-tumor activity and favorable tolerability profiles, we believe that we can disrupt the progression of disease and return patients to better living today. To achieve this mission, we strive to create and maintain a corporate culture centered on people: both our patients and the employees of ImmunoGen who will deliver our therapies to those patients. To that end, how we do our work is equally as important as what we achieve. The foundation of how we go about our work is our core values:

ImmunoGen’s culture and diversity, equity, and inclusion (DEI) philosophy also shape our approach to environmental, social, and governance (ESG). As we look forward, we see that the success of our business relies on our effective management of key ESG matters. That is why, in 2021, we formalized oversight of ESG matters within our Board committees. The Governance and Nominating Committee now oversees the Company’s ESG strategy, initiatives, and policies. These responsibilities have been codified in the committee charter. Governance and Nominating Committee members will receive regular reports from management on ESG-related matters and initiatives. The Board also strengthened its oversight of the Company’s human capital management and DEI strategies by embedding their review within the Compensation Committee. This update to the Compensation Committee charter is consistent with the Company’s commitment to attract, retain, and develop the highest quality talent now and in the future. Taken together, these expanded Board responsibilities mark an important first step in developing an effective ESG strategy.

Table of Contents

Table of Contents

our predecessor equity plans, the 2016 Plan (as defined below) or the 2006 Employee, Director and Consultant Equity Incentive Plan (the “2006 Plan”), depending on the grant date of the deferred stock units) at a rate of one share for each vested deferred stock unit then held. Any deferred stock units that remain unvested at that time will be forfeited. All unvested deferred stock units will automatically vest immediately prior to the occurrence of a change of control, as defined in the 2018 Plan (or the substantially identical definition in the 2016 Plan or 2006 Plan, as applicable). We believe that the requirement that non-employee directors hold their deferred stock units for the duration of their tenure on our Board mitigates excessive risk-taking and directly aligns a substantial portion of director compensation with the creation of long-term shareholder value.

Stock Options

Non-employee directors also receive stock option awards as follows:

All unvested stock option awards granted to non-employee directors will automatically vest immediately as of the date of a change of control, as defined in the 2018 Plan.

The Governance and Nominating Committee will periodically review the size of the foregoing deferred stock unit and stock option awards to ensure that, in light of changes in the market price of our common stock, these awards are generally aligned with equity awards granted to the outside directors of our peer group.

Compensation paid to the non-employee members of our Board of Directors with respect to 2021 was as follows:

Table of Contents

Are the outside directors subject to share ownership guidelines?

Yes. Our Board of Directors adopted, effective as of July 1, 2014, share ownership guidelines for our outside directors. The guidelines provide that outside directors are expected to own shares of our common stock having an aggregate value equal to at least three times the annual meeting fee (whether such fee is paid in cash or, at the director’s option, in deferred stock units), excluding Lead Director/Chair of the Board and committee-related fees. The current outside directors (other than Mr. Arbuckle, Ms. McCain, and Dr. Thackray, who became directors in 2018, 2021, and 2021, respectively) had five years from the date of the 2014 annual meeting of shareholders to achieve the ownership requirement, and new outside directors (Mr. Arbuckle, Ms. McCain, and Dr. Thackray) will have a similar five-year period following their election. The outside directors may satisfy the guidelines with shares owned directly or indirectly in a trust or by a spouse and/or minor children, vested deferred stock units, and vested stock options. In the case of deferred stock units or stock options, the aggregate exercise price or other cash consideration, if any, required to be paid for such shares is deducted in determining the aggregate value of the shares represented by such awards.

As of the initial measurement date of November 11, 2019, all but one of our outside directors who had served for at least five years met the ownership threshold in our guidelines. As previously disclosed, because of unexpected volatility in the price of our common stock, we extended that one director’s measurement date to November 11, 2020, at which time this director met the ownership threshold. The next measurement date for the directors, except for Mr. Arbuckle, Ms. McCain, and Dr. Thackray, will be November 11, 2022.

AMENDMENT TO OUR RESTATED ARTICLES OF ORGANIZATION
TO INCREASE THE NUMBER OF AUTHORIZED SHARES OF COMMON STOCK
FROM 300,000,000 TO 600,000,000
(Proposal 3)

There will be presented at the meeting a proposal to approve an amendment to our Restated Articles of Organization, which amendment was approved by our Board of Directors on April 1, 2022 and is subject to shareholder approval. The amendment increases the number of authorized shares of our common stock from 300,000,000 to 600,000,000.

The additional common stock to be authorized by approval of the amendment will have rights that are identical to our currently authorized common stock. Approval of the proposed amendment will not affect the rights of the holders of currently outstanding shares of our common stock, except for the effects incidental to increasing the number of shares of common stock if and when the additional shares are issued. If the amendment is approved, it will become effective upon the filing of Articles of Amendment of our Restated Articles of Organization with the Secretary of the Commonwealth of Massachusetts.

Table of Contents

As of April 8, 2022, there were 220,536,032 shares of our common stock issued, 32,798,418 shares of common stock reserved for issuance upon exercise of pre-funded warrants, and 36,929,607 shares of common stock reserved for issuance under our equity compensation plans, including our Employee Stock Purchase Plan (ESPP). Accordingly, as of that date, of the 300,000,000 shares of common stock currently authorized, there were fewer than 10,000,000 shares of common stock available for general corporate purposes.

Recommendation

The Board recommends that you vote “FOR” the proposal to amend our Restated Articles of Organization to increase the number of authorized shares of common stock from 300,000,000 to 600,000,000.

Purpose of the Proposed Amendment

Although as of the mailing date of this proxy statement the Board has no specific plans to issue shares of common stock in excess of the number currently authorized, the Board believes it continues to be in our best interest to have sufficient additional authorized but unissued shares of common stock available in order to provide flexibility for corporate action in the future. Our Board believes that the currently available unissued shares do not provide sufficient flexibility for corporate action in the future, without the delay and expense associated with repeated separate amendments to our Articles of Organization and convening a special meeting of shareholders. The additional shares may be used for various purposes, including, without limitation, raising capital, expanding our business or research and development programs through the acquisition of other businesses or products, equity compensation, and stock splits and dividends.

Possible Effects of the Proposed Amendment

If the shareholders approve the proposed amendment, the Board may cause the issuance of the additional shares of our common stock without further shareholder approval, except as may be required by law, regulatory authorities, or the rules of the Nasdaq Stock Market or any other stock exchange on which our shares may be listed at the time of any proposed issuance. Under our Restated Articles of Organization, shareholders do not have preemptive rights to subscribe for additional securities that may be issued by us, which means that current shareholders do not have a prior right to purchase any new issue of our securities in order to maintain their proportionate ownership of our common stock. In addition, if the Board elects to issue additional shares of common stock, such issuance could have a dilutive effect on earnings per share, voting power, and holdings of current shareholders.

In addition to the corporate purposes discussed above, the proposed amendment could, under certain circumstances, have an anti-takeover effect, although this is not the intent of the Board. For example, it may be possible for the Board to delay or impede a takeover or transfer of control of ImmunoGen by causing such additional authorized shares to be issued to holders who might side with the Board in opposing a takeover bid that the Board determines is not in the best interests of ImmunoGen and our shareholders. The amendment therefore may have the effect of discouraging unsolicited takeover attempts. By potentially discouraging initiation of any such unsolicited takeover attempt, the proposed amendment may limit the opportunity for our shareholders to dispose of their shares in takeover attempts or under a merger proposal. However, the Board is not aware of any attempt to take control of ImmunoGen and the Board has not presented this proposal with the intent that it be utilized as a type of anti-takeover defense.

​

AMENDMENT TO OUR 2018 EMPLOYEE, DIRECTOR AND CONSULTANT EQUITY INCENTIVE PLAN TO
INCREASE THE NUMBER OF SHARES AUTHORIZED FOR ISSUANCE THEREUNDER BY 13,000,000

(Proposal 4)

In 2018, our Board adopted, and our shareholders subsequently approved the 2018 Plan. Following shareholder approval of the 2018 Plan, our 2016 Employee, Director and Consultant Equity Incentive Plan (the “2016 Plan”) was terminated. All outstanding awards under the 2016 Plan remain in effect, but no additional awards may be made under the 2016 Plan after June 20, 2018.

There will be presented at the meeting a proposal to approve an amendment to the 2018 Plan, which was approved by our Board of Directors on April 1, 2022 and is subject to shareholder approval. The amendment provides as follows:

●   an increase in the number of shares of our common stock authorized for issuance thereunder by 13,000,000.

Recommendation

The Board recommends a vote “FOR” the proposal to amend the 2018 Plan to increase the number of shares of our common stock issuable thereunder by 13,000,000.

Table of Contents

Summary of and Reasons for the Amendment to the 2018 Plan

We believe that the effective use of stock-based long-term compensation is vital to our ability to achieve strong performance in the future. Awards under the 2018 Plan are intended to attract, retain, and motivate key individuals, further align employee and shareholder interests, and closely link compensation with our corporate performance. We believe that the 2018 Plan is essential to allow us to continue to provide long-term, equity-based incentives to present and future employees, consultants, and directors.

Increase in the number of shares of our common stock authorized for issuance under the Amended 2018 Plan

The Board believes that the number of shares currently remaining available for issuance pursuant to future awards under the 2018 Plan (4,714,338 shares as of April 8, 2022) is not sufficient for future granting needs given planned future growth of the company. Accordingly, the proposed amendment to the 2018 Plan increases the number of shares of common stock authorized for issuance thereunder by 13,000,000. Based on the closing price of our common stock as reported on the Nasdaq Global Select Market on April 8, 2022 ($5.53), the market value of the shares currently available for issuance under future awards, plus the additional 13,000,000 shares, would be $97,960,289.

As of April 8, 2022, 24,027,675 shares were subject to outstanding stock option and other stock-based awards granted under the 2018 Plan and the discontinued 2016 and 2006 Plans (in all cases, assuming performance goals are met in full with respect to performance-based awards). The foregoing number also includes shares of our common stock issuable upon redemption of outstanding deferred share units credited to our non-employee directors under our Compensation Policy for Non-Employee Directors but does not include the number of shares subject to outstanding stock options and other stock-based awards granted under the ImmunoGen, Inc. Inducement Equity Incentive Plan (the “Inducement Plan”) (3,586,300 shares outstanding as of April 8, 2022). Accordingly, as of April 8, 2022, the equity overhang, represented by the sum of all outstanding stock option and other stock-based awards, other than those granted under the Inducement Plan, plus the number of shares available for issuance pursuant to future awards under the 2018 Plan, was 11.5%. If the proposed amendment to the 2018 Plan is approved by shareholders, the equity overhang would be 15.9%, not taking into account awards granted under the Inducement Plan. Equity overhang was calculated in each instance above as (a) the sum of (i) all shares issuable upon exercise, vesting, or redemption of outstanding awards, plus (ii) all shares available for issuance pursuant to future awards, as a percentage of (b) the sum of (i) the number of shares of our common stock outstanding as of April 8, 2022, plus (ii) the number of shares described in clause (a) above.

The Compensation Committee of our Board of Directors has considered our historical annual burn rate in granting awards under the 2018 Plan and previous plans, and believes that our burn rate, determined on this basis, is reasonable for a development stage company that is prudently planning for success. We also believe that it is appropriate to exclude the impact of new hire awards, which are determined primarily by competitive market conditions, in evaluating our burn rate. The following table shows our 3-year burn rate history (adjusted to exclude new hire awards under the Inducement Plan):

1)    Adjusted gross burn rate is calculated as a result of (a) shares subject to awards granted during the applicable calendar year (excluding new hire awards), divided by (b) the weighted average common shares outstanding during the applicable calendar year.

2)    Adjusted net burn rate is calculated as the result of (a) shares subject to awards granted during the applicable calendar year (excluding new hire awards), minus shares subject to awards that were forfeited, canceled, or terminated (other than upon exercise) during the applicable calendar year, divided by (b) the weighted average common shares outstanding during the applicable calendar year.

Our Board believes that if the proposed amendment to the 2018 Plan is approved by shareholders, the additional shares, when added to the shares currently available for issuance under future awards, will, based on data available as of the date of this proxy statement, enable us to continue to grant equity-based awards in line with our historical practices for approximately two additional years following the current year.

Summary of Material Features of the Amended 2018 Plan

The following description of the material features of the 2018 Plan, giving effect to the adoption of the proposed amendment (the “Amended 2018 Plan”), is intended to be a summary only. This summary is qualified in its entirety by the full text of the Amended 2018 Plan that is attached to this proxy statement as Exhibit A.

Table of Contents

Eligibility. The Amended 2018 Plan allows us, under the direction of the Compensation Committee, to make grants of stock options, restricted and unrestricted stock awards, and other stock-based awards to employees, directors, and consultants (123 employees, eight non-employee directors, and zero consultants are eligible to receive awards under the Amended 2018 Plan as of April 8, 2022) who, in the opinion of the Compensation Committee, are in a position to make a significant contribution to our long-term success.

Shares Available for Issuance. The Amended 2018 Plan provides for the issuance of a number of shares equal to the sum of (i) 13,000,000 plus (ii) 4,714,338 shares remaining under the Amended 2018 Plan as of April 1, 2022, the date the Board of Directors approved the amendment to the 2018 Plan, plus (iii) the number of shares underlying any stock option and other stock-based awards previously granted under the Amended 2018 Plan, the 2016 Plan, and the 2006 Plan that are forfeited, expire, or are canceled without delivery of shares of common stock or which result in the forfeiture of shares of common stock back to the Company on or after April 1, 2022 (in the case of (ii) and (iii) not to exceed 28,742,013 shares in the aggregate). Shares of common stock reserved for awards under the Amended 2018 Plan that expire or are forfeited, canceled, or otherwise terminated (other than by exercise), or result in any shares not being issued, generally are added back to the share reserve available for future awards. However, shares of common stock tendered in payment for an award or shares of common stock withheld for taxes are not available again for future awards. In addition, shares purchased by us with the proceeds of the option exercise price of any option award may not be reissued under the Amended 2018 Plan.

Any awards under the Amended 2018 Plan having an intrinsic value that is not solely dependent on appreciation in the price of our common stock after the date of grant, also known as “full-value awards,” will be treated, for purposes of determining the number of shares of our common stock available for issuance under the Amended 2018 Plan, as one and one-quarter (1.25) shares for each share subject to such full-value awards. In addition, the aggregate grant date fair value of shares to be awarded to any non-employee director in any calendar year may not exceed $500,000, except that this limitation shall not apply to stock-based awards made pursuant to an election by a non-employee director to receive such stock-based award in lieu of cash for all or a portion of cash fees to be received for service on our Board of Directors or any committee thereof.

Stock Options. Stock options granted under the Amended 2018 Plan may be either incentive stock options, which are intended to satisfy the requirements of Section 422 of the Internal Revenue Code (the “Code”), or non-qualified stock options, which are not intended to meet those requirements. Incentive Stock Options may be granted to employees of ImmunoGen and its affiliates. The exercise price of a stock option may not be less than 100% of the closing price of a share of our common stock on the date of grant. The term of stock options granted under the Amended 2018 Plan may not be longer than ten years. Moreover, if an incentive stock option is granted to an individual who owns more than 10% of the combined voting power of all classes of our capital stock, the exercise price may not be less than 110% of the closing price of a share of our common stock on the date of grant and the term of the option may not be longer than five years.

Award agreements for stock options include rules for exercise of the stock options after termination of service. Options may not be exercised unless they are vested, and no option may be exercised after the end of the term set forth in the award agreement. Generally, stock options will be exercisable for three months after termination of service for any reason other than death or total and permanent disability, and for 12 months after termination of service on account of death or total and permanent disability. Options, however, will not be exercisable if the termination of service was due to cause.

Restricted Stock. Restricted stock is common stock that is subject to restrictions, including a prohibition against transfer and a substantial risk of forfeiture, until the end of a “restricted period” during which the grantee must satisfy certain vesting conditions. If the grantee does not satisfy the vesting conditions by the end of the restricted period, the restricted stock is forfeited.

During the restricted period, the holder of restricted stock has certain of the rights and privileges of a regular shareholder, except that the restrictions set forth in the applicable award agreement apply. For example, the holder of restricted stock may vote the shares, but he or she may not sell the shares until the restrictions are lifted. In addition, dividends may accrue but shall not be paid prior to and only to the extent that, the shares subject to the restrictions vest.

Restricted Stock Units and Performance Stock Units. Restricted stock units and performance stock units provide the grantee with the right to receive a fixed number of shares of common stock in the future based on the grantee providing continuing service for the period specified in the award agreement, in the case of restricted stock units, and if the performance goals are met, in the case of performance stock units. If the vesting is achieved the grantee shall be entitled to receive such number of shares based on the number of units specified in the award agreement. Dividend equivalents may accrue but shall not be paid prior to and only to the extent that, the grantee receives the shares related to the stock units upon vesting. If the grantee does not satisfy the vesting conditions by the end of the applicable period specified in the award agreement the award is forfeited and shares are not issued.

Table of Contents

Other Stock-Based Awards. The Amended 2018 Plan also authorizes the grant of other types of stock-based compensation including, but not limited to, stock appreciation rights, phantom stock awards, deferred stock units, and unrestricted stock awards. Under no circumstances may the agreement covering stock appreciation rights (a) have an exercise price per share that is less than 100% of the closing price of a share of our common stock on the date of grant or (b) expire more than ten years following the date of grant. We will issue shares of our common stock under the Amended 2018 Plan to our non-employee directors upon redemption of deferred share units that may be granted to our non-employee directors under our Compensation Plan for Non-Employee Directors after June 20, 2018.

Except in the case of death, disability, or “change of control” (as defined in the Amended 2018 Plan), no award shall vest, and no right of ImmunoGen to restrict or reacquire shares subject to full value awards shall lapse, less than one year from the date of grant. However, awards may be granted having time-based vesting of less than one year from the date of grant so long as no more than 5% of the shares reserved for issuance under the Amended 2018 Plan are granted in the aggregate pursuant to such awards.

Plan Administration. In accordance with the terms of the Amended 2018 Plan, our Board of Directors has authorized the Compensation Committee to administer the Amended 2018 Plan. The Compensation Committee may delegate part of its authority and powers under the Amended 2018 Plan to one or more of our directors, but only the Compensation Committee can make awards to participants who are subject to the reporting and other requirements of Section 16 of the Securities Exchange Act of 1934. In accordance with the provisions of the Amended 2018 Plan, the Compensation Committee determines the terms of awards, including:

In addition, the Compensation Committee may, in its discretion, amend any term or condition of an outstanding award provided (i) such term or condition as amended is not prohibited by the Amended 2018 Plan, and (ii) any such amendment does not impact the rights of a participant to whom such award was made without the participant’s consent (or in the event of the death of the participant, the participant’s survivors).

Stock Dividends and Stock Splits. If our common stock is subdivided or combined into a greater or smaller number of shares or if we issue any shares of common stock as a stock dividend, the number of shares of our common stock thereafter deliverable upon the exercise of an outstanding option or upon issuance under another type of award shall be appropriately increased or decreased proportionately, and appropriate adjustments shall be made in the per share purchase price and performance goals applicable to performance-based awards, if any, to reflect such subdivision, combination, or stock dividend.

Other Dividends. Except as expressly provided in the Amended 2018 Plan, no adjustments shall be made for dividends paid in cash or in property (including without limitation, securities) of the Company prior to any issuance of shares pursuant to an award.

Corporate Transactions. Upon a merger, consolidation, or other reorganization event, our Board of Directors (or an entity assuming the obligations of the company under the Amended 2018 Plan), may, in its sole discretion, take any one or more of the following actions pursuant to the Amended 2018 Plan, as to some or all outstanding awards:

Table of Contents

Amendment and Termination. The Amended 2018 Plan may be amended by our shareholders. It may also be amended by our Board of Directors, provided that any amendment approved by our Board which requires shareholder approval (1) under the rules of Nasdaq, (2) in order to ensure favorable federal income tax treatment for any incentive stock options under Section 422 of the Code, or (3) for any other reason, is subject to obtaining such shareholder approval. However, no such action may adversely affect any rights under any outstanding awards without the holder’s consent unless such amendment is required by applicable law or necessary to preserve the economic value of such award. Other than in connection with stock dividends, stock splits, and corporate transactions, as summarized above, (i) the exercise price of an option may not be reduced, (ii) an option may not be canceled in exchange for a replacement option having a lower exercise price, or for another award or for cash, and (iii) no other action may be taken that is considered a direct or indirect “repricing,” in each case without shareholder approval. In addition, except in the case of death, disability or “change of control” (as defined in the Amended 2018 Plan), outstanding awards may not be amended in a manner that would accelerate the exercisability or vesting of, or lapsing of any right by ImmunoGen to restrict or reacquire shares subject to, all or any portion of any award.

Duration of the Amended 2018 Plan. The Amended 2018 Plan will expire on March 28, 2028. No awards may be made after termination of the Amended 2018 Plan, although previously granted awards may continue beyond the termination date in accordance with their terms.

Federal Income Tax Consequences

The material federal income tax consequences of the issuance and exercise of stock options and other awards under the Amended 2018 Plan, based on the current provisions of the Code and regulations, are as follows. Changes to these laws could alter the tax consequences described below. This summary assumes that all awards granted under the Amended 2018 Plan are exempt from or comply with the rules under Section 409A of the Code related to nonqualified deferred compensation.

Incentive Stock Options. Incentive stock options are intended to qualify for treatment under Section 422 of the Code. An incentive stock option does not result in taxable income to the optionee or deduction to us at the time it is granted or exercised, provided that no disposition is made by the optionee of the shares acquired pursuant to the option within two years after the date of grant of the option nor within one year after the date of issuance of shares to the optionee (referred to as the “ISO holding period”). However, the difference between the fair market value of the shares on the date of exercise and the option price will be an item of tax preference includible in “alternative minimum taxable income” of the optionee. Upon disposition of the shares after the expiration of the ISO holding period, the optionee will generally recognize long term capital gain or loss based on the difference between the disposition proceeds and the option price paid for the shares. If the shares are disposed of prior to the expiration of the ISO holding period, the optionee generally will recognize taxable compensation, and we will have a corresponding deduction (subject to certain limitations imposed under the Code), in the year of the disposition, equal to the excess of the fair market value of the shares on the date of exercise of the option over the option price (or, in some cases, the excess of the shares’ fair market value at time of disposition over the option price). Any additional gain realized on the disposition will normally constitute capital gain.

Non-Qualified Options. Options otherwise qualifying as incentive stock options, to the extent the aggregate fair market value of shares with respect to which such options are first exercisable by an individual in any calendar year exceeds $100,000, and options designated as non-qualified options, will be treated as options that are not incentive stock options.

A non-qualified option ordinarily will not result in income to the optionee or deduction to us at the time of grant. The optionee will recognize compensation income at the time of exercise of such non-qualified option in an amount equal to the excess of the then fair market value of the shares over the option price per share. Such compensation income of optionees may be subject to withholding taxes, and a deduction may then be allowable to us in an amount equal to the optionee’s compensation income (subject to certain limitations imposed under the Code).

An optionee’s initial basis in shares so acquired will be the amount paid on exercise of the non-qualified option plus the amount of any corresponding compensation income. Any gain or loss as a result of a subsequent disposition of the shares so acquired will be capital gain or loss (subject to certain limitations imposed under the Code).

Stock Grants. With respect to stock grants under the Amended 2018 Plan that result in the issuance of shares that are either not restricted as to transferability or not subject to a substantial risk of forfeiture, the grantee must generally recognize ordinary income equal to the fair market value of shares received. Thus, deferral of the time of issuance will generally result in the deferral of the time the grantee will be liable for income taxes with respect to such issuance. We generally will be entitled to a deduction in an amount equal to the ordinary income recognized by the grantee.

Table of Contents

With respect to stock grants involving the issuance of shares that are restricted as to transferability and subject to a substantial risk of forfeiture, the grantee must generally recognize ordinary income equal to the fair market value of the shares received at the first time the shares become transferable or are not subject to a substantial risk of forfeiture, whichever occurs earlier. A grantee may elect to be taxed at the time of receipt of shares rather than upon lapse of restrictions on transferability or substantial risk of forfeiture, but if the grantee subsequently forfeits such shares, the grantee would not be entitled to any tax deduction, including as a capital loss, for the value of the shares on which he previously paid tax. The grantee must file such election with the Internal Revenue Service within 30 days of the receipt of the shares. We generally will be entitled to a deduction in an amount equal to the ordinary income recognized by the grantee (subject to certain limitations imposed under the Code).

Stock Units. The grantee recognizes no income until the issuance of the shares. At that time, the grantee must generally recognize ordinary income equal to the fair market value of the shares received. We generally will be entitled to a deduction in an amount equal to the ordinary income recognized by the grantee (subject to certain limitations imposed under the Code).

New Plan Benefits

None of the 13,000,000 additional shares of common stock for which shareholder approval is being sought may be made the basis of awards under the Amended 2018 Plan prior to shareholder approval of the amendment to that plan. Future options and other awards under the Amended 2018 Plan are subject to the discretion of the Compensation Committee, and therefore it is not possible to identify the persons who will receive options or other awards under the Amended 2018 Plan in the future, nor the amount of any such future options or other awards. The following table shows the awards that were granted to our named executive officers, executive officers as a group, non-executive officers as a group, and directors as a group, in each case for the year ended December 31, 2021 under the 2018 Plan:

Table of Contents

Outstanding Awards under Equity Incentive Plans. As of April 8, 2022, there were 26,937,508 shares subject to issuance upon exercise of outstanding options under all of our equity compensation plans, at a weighted average exercise price of $6.08, and a weighted average remaining life of 7.75 years. There were a total of 75,000 issued and outstanding restricted stock units that remain subject to forfeiture, 72,500 shares subject to DSUs that remain subject to forfeiture, and 528,966 shares subject to vested DSUs. All DSUs are held by non-management directors. As of April 8, 2022, 8,125,063 shares were available for future issuance under those plans (4,714,338 shares remaining under the Amended 2018 Plan and 3,410,725 under the Inducement Plan).

Where can I obtain more information about ImmunoGen’s executive officers?

Biographical information concerning our executive officers and their ages can be found in Item 1 entitled “Business – Information about our Executive Officers” in our Annual Report on Form 10-K for the year ended December 31, 2021, which information is incorporated by reference into this proxy statement.

Table of Contents

Table of Contents

IMGN151

​

Leadership and Financials

​

Due to the significant progress across the business in the past year, we enter 2022 with significant momentum and strong prospects for the business, including: the potential launch of our first product, expected top-line data for our second pivotal program, anticipated advancement of our earlier-stage portfolio, and continued expansion of our pipeline and research capabilities.

2021 Compensation Highlights

Our compensation program is well-structured to incentivize our leadership team to focus on the strategic objectives that, when achieved, will help to create shareholder value. To this end, we regularly evaluate and make changes to our executive program to ensure that our approach aligns with shareholder interests as well as with competitive and appropriate pay practices for our industry.

Annual Incentive Plan Payout

We experienced delays in site activation and patient accrual in some of our clinical studies primarily due to the impact of the COVID-19 pandemic, which led to a shortfall in our enrollment objectives for the year. In collaboration with our vendors, our team responded quickly to adapt to the pandemic environment. These efforts mitigated enrollment delays and resulted in approximately a one quarter extension to our timelines for BLA submission. Apart from clinical delays, we met or exceeded most of the remaining objectives set forth in our annual incentive plan. After considering our overall performance, including the missed enrollment objectives, our Compensation Committee determined that the corporate objectives under our annual incentive plan were achieved at 90% of target.

Continued Strong Say-on-Pay Support

Our annual “say-on-pay” proposal received the support of over 98% of votes cast at our annual shareholder meeting held in June 2021. The Compensation Committee believes this reflects strong shareholder support for not only the executive compensation program structure and pay philosophy, but also for the steps that the committee has taken in the last several years to improve the executive compensation program, incorporate shareholder feedback, and navigate the uncertainties brought on by the pandemic. While this level of support is encouraging, the committee will continue to seek shareholder feedback on our executive compensation program to ensure that executive interests continue to be closely aligned with shareholder perspectives and interests.

How Our Pay Program Works

The Compensation Committee has structured our executive compensation program to ensure that our NEOs are compensated in a manner consistent with shareholder interests as well as with competitive and appropriate pay practices for our industry. The following are important features of the design and operation of our executive compensation program:

Components of Pay

The components of our executive compensation program consist primarily of elements that are available to all of our employees, including base salary, annual performance-based bonuses, long-term equity awards, and broad-based benefits.

​

Table of Contents

​

Target Pay Mix

The Compensation Committee does not apply a specific formula for allocating total compensation among the various components. Instead, the Compensation Committee uses its judgment, in consultation with Radford, the Compensation Committee’s independent executive compensation consultant, to establish a mix of current, short-term, and long-term incentive compensation, and cash and equity compensation, for each NEO. As can be seen in the graphs below, a large percentage of executive pay is variable and “at-risk” (90% for the CEO, and 78% on average for other NEOs), meaning that value will only be received by the executive if corporate and stock price performance are strong. Our use of a substantial level of variable and “at risk” compensation supports our pay-for-performance culture and pay program. The balance between these components may change from year to year based on corporate strategy and objectives, among other considerations.

For 2021, our NEOs had the following target pay mix:

Pay and Performance

The Compensation Committee has designed an executive compensation program that carefully balances our desire to attract, retain, and motivate the industry’s top talent, while focusing on creating long-term sustainable growth in shareholder value. We believe that the foundation of our program is a pay-for-performance philosophy. As indicated below in the graphic of CEO pay over the past three years, the reported pay value – pay that is displayed in the Summary Compensation Table – is

Table of Contents

much different than the realizable pay that the CEO may actually receive. The significant difference in values is attributable to share price movement and reflects a clear picture of our pay-for-performance philosophy in action, as well as an example of how management and shareholder interests are closely aligned. The value of our CEO pay packages as of the end of the last three fiscal years are displayed in the green bars. As of year-end 2021, Mr. Enyedy’s 2021 options were underwater, and were therefore not realizable.

“Reported CEO Pay” is the value reported in the Summary Compensation Table for base salary, non-equity incentive compensation, and option awards, adjusted to include, for 2020, the grant date value of performance-based awards granted in such year, assuming performance goals are met in full; and adjusted to exclude, for 2021, $1.1 million of incremental fair value pursuant to FASB ASC Topic 718 resulting from a modification of the performance-based awards granted in 2020.

“Realizable CEO Pay” is defined as the compensation earned or deliverable for each year, including: actual salary received, actual annual bonus received, and the intrinsic value of stock options granted in that year, including performance-based awards assuming performance goals are met in full, as valued on December 31, 2021 using the year-end share price of $7.42 per share.

Table of Contents

Our executive compensation philosophy is designed to enable us to attract, retain, and motivate key executives to achieve our long-term objective of creating significant shareholder value through our antibody-drug conjugate technology and expertise. In this regard, we set executive compensation with two principal goals: first, generally to align fixed compensation and target incentive compensation with the market median for our peer group; and second, to align a substantial portion of that compensation with the creation of long-term value for our shareholders.

Attracting and retaining key executives is particularly challenging in the biotechnology industry, where executives are required to remain focused and committed throughout years of product development, regulatory approvals, and, at times, financial instability. The market for executive talent in our industry is highly competitive, with many biotechnology companies that are at a similar stage of development located in general proximity to our corporate office outside of Boston, Massachusetts.

Role of the Compensation Committee

The Compensation Committee has responsibility for establishing our executive compensation philosophy and the design of our executive compensation program, as well as for determining the level of compensation awarded to our NEOs. Information about the Compensation Committee, including its composition, responsibilities, and processes, can be found elsewhere in this proxy statement.

In addition to evaluating our executives’ contributions and performance in light of corporate objectives and individual performance, we also base our compensation decisions on market considerations. The Compensation Committee benchmarks our cash and equity incentive compensation against programs available to executive officers in comparable roles at peer companies. All forms of compensation are evaluated relative to the market median for our peer group. Individual compensation pay levels may vary from this reference point based on recent individual performance and other considerations, including breadth of experience, the anticipated out-of-pocket costs and level of difficulty in replacing an executive with someone of comparable experience and skill, and the initial compensation levels required to attract qualified new hires.

Role of Independent Compensation Consultant

The Compensation Committee retained the services of Radford as its independent executive compensation consultant due to its extensive analytical and compensation expertise in the biotechnology and pharmaceutical industry. In this capacity,

Table of Contents

Radford has advised the Compensation Committee on compensation matters related to the executive and director compensation programs. In 2021, Radford assisted the Compensation Committee with, among other things:

The Compensation Committee has the sole authority to engage and terminate Radford’s services, as well as to approve Radford’s compensation. Radford makes recommendations to the Compensation Committee but has no authority to make compensation decisions on our behalf or on behalf of the Compensation Committee. Radford reported to the Compensation Committee and had direct access to the Chair and the other members of the Compensation Committee. Beyond advice related to the executive and director compensation programs as described above, Radford did not provide other services to us in 2021.

The Compensation Committee conducted a specific review of its relationship with Radford in the past year and determined that Radford’s work for the Compensation Committee did not raise any conflicts of interest. Radford’s work has conformed to the independence factors and guidance provided by the Dodd-Frank Wall Street Reform and Consumer Protection Act, the SEC, and Nasdaq.

Role of Management

To aid the Compensation Committee in its responsibilities, the CEO presents to the Compensation Committee his assessment of the performance and achievements for each of the NEOs (other than himself) for the prior year. The Compensation Committee gives considerable weight to the CEO’s performance evaluations of the other NEOs, since he has direct knowledge of the criticality of their work, performance, and contributions. Our CEO does not participate in the Compensation Committee’s deliberations or decisions regarding his own compensation.

The Compensation Committee has delegated to our CEO the authority to grant stock options and restricted stock awards under our 2018 Plan to individuals who are not subject to the reporting and other requirements of Section 16 of the Securities Exchange Act of 1934, including new hire awards and equity recognition awards, both subject to guidelines established by the Compensation Committee.

Use of Market Data and Peer Group Analysis

When considering executive compensation decisions, the Compensation Committee believes it is important to be informed as to the current compensation practices of comparable publicly-held companies in the life sciences industry, especially to understand the competitive compensation required to attract and retain individuals with the necessary specific expertise and experience.

As in prior years, the Compensation Committee considered numerous factors when setting executive pay levels for 2021. While the Compensation Committee believes that referencing peer group compensation levels as part of the pay setting process is helpful in determining market-competitive compensation for our executives, it does not tie any pay elements directly to specific benchmarks within the peer group. Instead, the Compensation Committee considers peer data as part of a market-check analysis that is used in conjunction with its assessments of numerous other factors, including: a review of industry survey data; employee knowledge, skill, and experience; individual performance and contribution; scope of current and expected future responsibilities; and any retention concerns.

2021 Peer Group

In September 2020, based on the recommendations and assistance of Radford, the Compensation Committee reviewed the members of our then-current peer group to determine if each peer company continued to be an appropriate reference point for purposes of making 2021 executive compensation decisions. With the assistance of Radford, the Compensation Committee considered several factors in determining the appropriate peer group for 2021, including:

Table of Contents

Using the aforementioned criteria, in consultation with Radford, the Compensation Committee determined that the 2021 peer group would consist of the following 21 companies:

* New for 2021

For 2021, ChemoCentryx, Dicerna Pharmaceuticals, Idera Pharmaceuticals, and Momenta Pharmaceuticals were removed as a result of not meeting market capitalization selection criteria, and Stemline Therapeutics was removed due to its acquisition by the Menarini Group.

Compensation Risk Oversight

Our compensation program aims to avoid any incentives for executives to take imprudent risks that might harm us or our shareholders. Our Compensation Committee has reviewed the compensation program with regards to compensation-related risk and concluded that our compensation policies and practices are not reasonably likely to have a material adverse effect on us.

Our overall executive compensation program consists of fixed elements, such as base salary and benefits, and variable performance-based elements, such as annual and long-term incentives. Our fixed compensation elements are designed to provide a predictable source of income to our executives. Our variable performance-based elements are designed to reward performance at three levels: individual performance, actual corporate performance compared to annual business goals, and long-term shareholder value creation.

We compensate our executives principally through base salary, performance-based annual cash incentives, and equity awards. Additionally, executives generally receive sign-on cash incentives upon hire. The objective of this approach is to remain competitive with other companies in our industry, while ensuring that our executives are given the appropriate incentives to achieve near-term objectives and at the same time create long-term shareholder value.

Base Salaries

We provide our executive officers with a level of fixed cash compensation in the form of a base salary that reflects their scope of responsibility and organizational impact, as well as individual performance. In setting salaries for our executive officers, the Compensation Committee reviews independently prepared surveys of biotechnology industry compensation as well as other available information on base salaries in our peer group for executive officers in comparable positions.

When setting base salaries, considerations include, but are not limited to:

The Compensation Committee does not apply any specific formulas to determine increases in base salaries for our executive officers, but instead makes an evaluation of the aforementioned considerations. In setting base salaries for our executive officers (other than the CEO), the Compensation Committee will also consider the recommendation of the CEO and the CEO’s evaluation of each executive’s respective performance.

Table of Contents

Based on the foregoing considerations, the Compensation Committee adjusted base salaries for our NEOs for 2021, effective as of March 1, 2021, as follows:

Annual Performance-Based Cash Incentives

Historically, we have provided our executives with short-term incentive compensation through our annual cash incentive program. We believe that annual incentives hold executives accountable, reward executives based on actual business results, and help create a “pay-for-performance” culture.

2021 Incentive Opportunities

Under our annual cash incentive plan, every employee, including each NEO, has an established annual performance-based incentive target, which is equal to a percentage of the employee’s base salary. This percentage increases as levels of responsibility increase. A participant’s annual base salary and target cash incentive opportunity as of the last day of the performance period are generally used to calculate earned incentives. The actual earned annual incentive amount, (“AIP”), if any, is calculated based on the achievement of corporate and individual goals and objectives. For 2021, our NEOs had the following annual cash incentive opportunities:

The 2021 target incentive opportunities were unchanged from 2020 targets for all continuing NEOs, including our CEO.

2021 Performance Criteria

Annual incentives are based on two sets of objectives: corporate and individual.

First, the Compensation Committee annually establishes key performance criteria, based upon the corporate goals and objectives for the year, and evaluates our performance against those criteria in its determination of whether annual bonuses will be paid to our employees, including our executives. Key corporate performance criteria may include any or all of the following:

Table of Contents

In establishing key performance criteria for the annual incentive program, the Compensation Committee selects specific corporate objectives directed primarily to the future success of our business and the creation of long-term shareholder value.

For 2021, the Compensation Committee established the key corporate performance criteria to be used in determining annual cash incentives. However, consistent with recent practice, the Compensation Committee chose to not assign weights to specific criteria, preferring to take a more holistic view of our achievements against the corporate objectives, as well as considerations, where warranted, of exemplary performance.

Once achievement versus corporate objectives is determined, our CEO will evaluate the other executive officers’ achievement against pre-established individual objectives and, based on these evaluations, the Compensation Committee will determine a percentage for each executive officer that can range from 0% to 125%, which percentage will then be applied to the corporate performance percentage to determine the executive officer’s payout. Our CEO’s payout under our annual incentive plan is based solely on the corporate performance percentage.

To illustrate, annual cash incentives are determined as follows (for all employees other than the CEO, whose annual incentive opportunity does not contain an "Individual Objectives” component, as discussed above):

2021 Corporate Objectives

The Compensation Committee determines an overall bonus pool consisting of a percentage of the aggregate target cash incentives for all eligible employees based on the achievement of pre-established corporate objectives. The percentage may range from 0% to 150%. If the Compensation Committee determines that, based on its evaluation of our performance toward the corporate objectives, the earned incentive percentage would be less than 50% of target, then no cash incentives associated with the corporate performance portion of the annual incentive plan would be paid. Establishing a corporate performance percentage exceeding 100% would be based on the Compensation Committee’s determination of exceptional performance.

Table of Contents

In January 2021, the Compensation Committee approved 2021 corporate objectives, which were set to align with the short-term strategic priorities of the business. The corporate objectives, and achievement versus those objectives, were as follows in the past year:

After considering our performance as a whole versus these corporate objectives and factoring in delays resulting from the COVID-19 pandemic, the Compensation Committee approved a 90% corporate performance achievement level for 2021.

Table of Contents

Individual Objectives

Individual performance multipliers for each NEO (other than the CEO, whose annual incentive opportunity is entirely tied to corporate objectives) were determined by the Compensation Committee after receiving our CEO’s evaluation of the other executive officers’ achievement against pre-established individual objectives and his recommendation regarding each officer’s individual performance multiplier. These individual objectives were tailored based on the executive’s role, responsibilities, and oversight.

For 2021, these individual objectives were as follows:

Ms. Harrington-Smith was hired on November 15, 2021 and, as such, was not eligible for the 2021 annual performance-based incentive.

Table of Contents

Sign-On Cash Incentives

Sign-on cash incentives are a standard component of our executive compensation program as it relates to new hire compensation. The CEO recommends to the Compensation Committee a sign-on cash incentive amount for new executive officers based on the individual’s role, experience, and market conditions. The Compensation Committee ultimately determines the amount of the sign-on cash incentive to be awarded.

In 2021, a sign-on cash incentive in the amount of $500,000 was awarded to Ms. Harrington-Smith as a component of her total compensation. If, within 12 months of her hire date, Ms. Harrington-Smith terminates her employment with us (other than by reason of death or disability), or we terminate her employment for cause, she must reimburse ImmunoGen a pro rata amount of the sign-on incentive (based on a period of 365 days) within 30 days of the termination date.

Equity Awards

Equity compensation is a key component of our executive compensation program. Our equity incentive plans are designed to retain our executive officers and other employees and align their long-term interests with the creation of long-term value for our shareholders.

The Compensation Committee determines the size of equity grants according to each executive officer’s position. To do so, the committee references peer group data and practices as provided by Radford. The Compensation Committee also considers each executive’s recent performance history, his or her potential for future responsibility, and criticality of his or her work to the long-term success of our company, among other factors. The Compensation Committee has the discretion to give relative weight to each of these factors as it determines an appropriate size of equity grants.

Historically, we have primarily relied on stock options to provide a long-term incentive for our executives to focus on creating long-term value and to help us to attract and retain key talent. We believe, as a general matter, that stock options provide an effective long-term incentive for all employees to create shareholder value as the benefit of the options cannot be realized unless there is an appreciation in the price of our common stock following the date they are granted. Stock option awards are commonly provided to a broad range of employees in the biotechnology industry due to the competitive nature of the industry.

In 2020, we granted performance-based stock options in addition to time-vesting stock options. This decision was based, in part, on shareholder input and was confirmed through market analysis as an appropriate addition to our equity program. Each of these performance-based stock options vest subject to the achievement of certain key goals over a four-year performance period. Twenty-five percent (25%) of the award is eligible to vest based on acceptance of a BLA for mirvetuximab by the FDA based on data from our SORAYA clinical trial, and the remaining 75% is eligible to vest based on the receipt of marketing approval for mirvetuximab from the FDA.

The first performance goal was contingent on the Company completing its submission of such BLA to the FDA on or prior to December 31, 2021. However, due to unanticipated delays in the clinical development of mirvetuximab that were primarily related to the COVID-19 pandemic, the Compensation Committee determined that this deadline was not aligned with the original purpose of the award and used its authority to extend the deadline to April 30, 2022. No other modifications were made to these awards.

The 2020 performance-based stock options provide a significant and ongoing performance-based incentive that aligns management’s interests with the achievement of key strategic and operational goals of the Company. As such, the Compensation Committee determined that it was appropriate to grant only time-based stock options in the annual equity granting cycle of 2021.

The following table shows the 2021 equity awards granted to our NEOs on February 5, 2021, unless otherwise noted:

Table of Contents

In accordance with our equity grant practices, the exercise price for these stock option grants was equal to the closing price of our common stock as reported by the Nasdaq Global Select Market on the date of grant.

All time-vesting stock options in the above table vest 25% on the first year anniversary of the grant date and the balance vests in twelve equal installments of 6.25%, quarterly over the following three years starting one quarter after the first year anniversary, subject to the executive officer’s continuous provision of service to us.

The time-vesting restricted stock units granted to Ms. Harrington-Smith vest annually over three years, starting on the first anniversary of the date of grant, subject to her continuous provision of service to us. The Compensation Committee provided part of Ms. Harrington-Smith’s sign-on award in the form of restricted stock units to compensate her for a portion of the equity awards from her prior employer that she forfeited as a result of joining the Company, to provide an additional incentive to motivate her to join the Company, and to encourage retention once she commenced employment.

Clawback Policy

We have adopted an incentive compensation recoupment policy that is applicable to our executive officers, and such other of our senior executive team as may be determined by the Compensation Committee. If we determine that we must restate our financial results as reported in a periodic or other report filed with the SEC to correct an accounting error due to material noncompliance with any financial reporting requirement under the U.S. securities laws, we will seek to recover, at the direction of the Compensation Committee, after it has reviewed the facts and circumstances that led to the requirement of the restatement and the costs and benefits of seeking recovery, incentive compensation, both cash and equity-based, awarded or paid to an officer covered by the policy whose intentional misconduct caused or contributed to the need for the restatement for a fiscal period if a lower award or payment would have been made to such officer based on the restated financial results.

Each NEO has five years from the later of the effective date of the guidelines, from their hiring date or from the date of designation as an executive officer, to achieve the ownership requirement. Our executive officers may satisfy the guidelines with shares owned directly or indirectly in a trust or by a spouse and/or minor children and with vested stock options. In the case of vested stock options, the aggregate exercise price required to be paid for such shares is deducted in determining the aggregate value of the shares represented by such awards.

Anti-Hedging and Pledging Policies

As part of our insider trading policy, we prohibit employees and directors from engaging in transactions that are designed to or have the effect of hedging or offsetting any decrease in the market value of our shares owned by such employees or directors. In particular, our insider trading policy prohibits the following transactions:

​

With respect to the last three items described above, the policy does authorize our General Counsel to approve such transactions in limited cases. However, no director or employee has requested approval to engage in any such transaction, nor has our General Counsel determined any circumstances under which such approval would be granted.

Table of Contents

Broad-Based Benefits

We offer employee benefit programs that are intended to provide financial protection and security for our employees and to reward them for the commitment we expect from them while employed by us. All of our named executive officers are eligible to participate in these programs on the same basis as our other employees.

These benefits include the following: medical, dental, and vision insurance; company-paid group life and accident insurance in an amount equal to two times base salary (up to $750,000); employee-paid supplemental group life and accident insurance (up to $500,000); short- and long-term disability insurance; and a qualified 401(k) retirement savings plan with a 50% company match of the first 6% of the participant’s eligible bi-weekly compensation contributed by the participant to the plan.

Severance Pay Plan for Vice Presidents and Higher

We maintain a severance pay plan for vice presidents and higher in which our NEOs participate. The Compensation Committee recognizes that, in order to induce candidates for executive positions to join us, it has been necessary to offer them certain severance benefits in the event their employment with us is involuntarily terminated without cause outside the context of a change in control.

An executive is entitled to severance benefits under this plan if the executive’s employment is terminated by us without cause outside the context of a change in control. Severance benefits include:

Change in Control Severance Agreements

We recognize that as a publicly-traded company, we may become the target of a proposal that could result in a change in control, and that such possibility and the uncertainty and questions that such a proposal may raise among management could cause our executive officers to leave or could distract them in the performance of their duties, to our detriment and that of our shareholders. We have entered into severance agreements with each of our executive officers that are designed to compensate them for the loss of their positions and the loss of anticipated benefits under their unvested equity compensation awards following a change in control. The agreements are intended to reinforce and encourage the continued attention of our executive officers to their assigned duties without distraction and to ensure the continued availability of each of our executive officers in the event of a proposed change in control transaction. We believe that these objectives are in our best interests and those of our shareholders. We also believe that it is in our best interests and those of our shareholders to offer such agreements to our executive officers insofar as we compete for executive talent in a highly competitive market in which companies routinely offer similar benefits to senior executives.

An executive officer is entitled to severance benefits if, within a period of two months before or 12 months after a change in control, the executive’s employment is terminated (1) by us other than for cause or disability or (2) by the executive for good reason. Severance benefits include:

Table of Contents

We believe these severance benefits are reasonable and appropriate for our executive officers in light of the anticipated time it takes high-level executives to secure new positions with responsibilities and compensation that are commensurate with their experience. We further believe that the equity awards granted to our executive officers have been reasonable in amount and that, in the event of a loss of employment within a year following a change in control, it is appropriate that our executive officers receive the full benefit under their equity compensation awards of the increase in our value attributable to the performance of the current management team.

Tax and Accounting Implications of Executive Compensation

Generally, Section 162(m) of the Internal Revenue Code disallows a tax deduction to any publicly-held corporation for any remuneration in excess of $1 million paid in any taxable year to certain current and former executive officers.

The Compensation Committee believes that it is in the best interests of our shareholders to maintain flexibility in our approach to executive compensation and to structure a program that we consider to be the most effective in attracting, motivating, and retaining key employees even if compensation paid under that program is not deductible in whole or in part.

​

Table of Contents

Table of Contents