ImmunoGen Presents Preclinical Data on IMGC936 at the AACR Virtual Annual Meeting

First-in-Class ADAM9-Targeting ADC Demonstrates Anti-Tumor Activity in Multiple Solid Tumor Models

ImmunoGen Inc. (Nasdaq: IMGN), a leader in the expanding field of antibody-drug conjugates (ADCs) for the treatment of cancer, today announced that a poster highlighting preclinical data for its novel ADAM9-targeting ADC, IMGC936, which is being investigated in multiple solid tumor types, is being presented at the American Association of Cancer Research (AACR) Virtual Annual Meeting April 10-15, 2021.

“ADAM9 is overexpressed in a wide range of solid tumors and minimally expressed on normal tissue, which makes it an ideal ADC target,” said Eric Westin, MD, Vice President, Clinical Development and Translational Sciences at ImmunoGen. “IMGC936 showed compelling anti-tumor activity against multiple patient-derived xenograft models with clinically relevant levels of ADAM9 and was well-tolerated across all models tested. We continue to enroll patients in our Phase 1 dose-escalation study of IMGC936 in multiple tumor types and look forward to sharing initial data by the end of 2021 or early 2022.”

POSTER PRESENTATION

• Title: “IMGC936, an investigational ADAM9-targeting antibody-drug conjugate, is active against patient-derived ADAM9-expressing xenograft models”
• Day/Time: Saturday, April 10, 2021 at 8:30 AM ET
• Session Category: Immunology
• Session Title: PO.IM02.10 - Therapeutic Antibodies, Including Engineered Antibodies
• Abstract: 1841

Additional information can be found at www.aacr.org.

ABOUT IMGC936

IMGC936 is a first-in-class ADAM9-targeting antibody-drug conjugate (ADC) that is comprised of a humanized antibody engineered to include a YTE mutation for enhanced exposure through improved recycling, a tri-peptide cleavable linker stable in circulation, and a next-generation DM21 maytansinoid payload, which is more potent and hydrophobic, resulting in increased bystander activity.

ADAM9 is a cell surface protein that belongs to the ADAM (a disintegrin and metalloproteinase) family of proteases, which have been implicated in cytokine and growth factor shedding and cell migration. Dysregulation of ADAM9 has been involved in tumor progression and metastasis, as well as pathological neovascularization. ADAM9 is overexpressed in multiple solid tumor types (e.g., non-small cell lung, gastric, pancreatic, triple-negative breast, and colorectal cancers) and minimally expressed on normal tissue, making ADAM9 an attractive target for ADC development.

IMGC936 is being co-developed with MacroGenics and is currently in a Phase 1 study enrolling patients with solid tumors that express ADAM9.

ABOUT IMMUNOGEN

ImmunoGen is developing the next generation of antibody-drug conjugates (ADCs) to improve outcomes for cancer patients. By generating targeted therapies with enhanced anti-tumor activity and favorable tolerability profiles, we aim to disrupt the progression of cancer and offer our patients more good days. We call this our commitment to TARGET A BETTER NOW™.

Learn more about who we are, what we do, and how we do it at www.immunogen.com.

FORWARD-LOOKING STATEMENTS

This press release includes forward-looking statements based on management's current expectations. These statements include, but are not limited to, ImmunoGen’s expectations related to: the occurrence, timing, and outcome of potential preclinical, clinical, and regulatory events related to the Company’s product candidates; and the presentation of preclinical and clinical data on the Company’s product candidates. For these statements, ImmunoGen claims the protection of the safe harbor for forward-looking statements provided by the Private Securities Litigation Reform Act of 1995. Various factors could cause ImmunoGen’s actual results to differ materially from those discussed or implied in the forward-looking statements, and you are cautioned not to place undue reliance on these forward-looking statements, which are current only as of the date of this release. Factors that could cause future results to differ materially from such expectations include, but are not limited to: the timing and outcome of the Company’s preclinical and clinical development processes; the difficulties inherent in the development of novel pharmaceuticals, including uncertainties as to the timing, expense, and results of preclinical studies, clinical trials, and regulatory processes; the Company’s ability to financially support its product programs; risks and uncertainties associated with the scale and duration of the COVID-19 pandemic and the resulting impact on ImmunoGen’s industry and business; and other factors as set forth in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 1, 2021, and other reports filed with the Securities and Exchange Commission.

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