ImmunoGen to Present Initial Data from FORWARD II Expansion Cohort of Mirvetuximab Soravtansine in Combination with KEYTRUDA ...

ImmunoGen, Inc., (Nasdaq: IMGN), a leader in the expanding field of antibody-drug conjugates (ADCs) for the treatment of cancer, today announced that initial findings from the FORWARD II expansion cohort of mirvetuximab soravtansine in combination with Merck’s anti-PD-1 therapy, KEYTRUDA® (pembrolizumab), will be presented at the European Society for Medical Oncology (ESMO) Congress from October 19-23, 2018 in Munich, Germany. The poster will include initial safety and preliminary anti-tumor activity for 46 patients with platinum-resistant ovarian cancer (PROC), of whom 35 have medium or high folate receptor alpha (FRα) expression.

Encouraging activity and favorable tolerability data from the FORWARD II dose-escalation cohort assessing mirvetuximab soravtansine in combination with KEYTRUDA in 14 heavily pre-treated patients with platinum-resistant epithelial ovarian cancer (EOC) were presented in March at the Society of Gynecologic Oncology (SGO) Annual Meeting. These findings supported enrollment of additional patients in an expansion cohort with full doses of both agents to further evaluate this combination in PROC.

“Based on the data presented at SGO, we advanced mirvetuximab soravtansine plus pembrolizumab into an expansion cohort focusing on PROC patients with medium and high FRα expression,” said Anna Berkenblit, M.D., Vice President and Chief Medical Officer of ImmunoGen. “We look forward to presenting initial findings at ESMO, as we evaluate several combinations that may ultimately enable us to treat more women with ovarian cancer.”

Details of ImmunoGen’s poster presentation are as follows:

Title: “Mirvetuximab soravtansine, a folate receptor alpha (FRα)-targeting antibody-drug conjugate (ADC), with pembrolizumab in platinum-resistant ovarian cancer (PROC): Initial results of an expansion cohort from FORWARD II, a Phase Ib study” (presentation number 949P)Date: October 20, 2018Time: 12:30 CESTLead author: Ursula Matulonis, M.D., Director and Program Leader, Gynecologic Oncology Program, Dana-Farber Cancer Institute, Boston, MA

Mirvetuximab soravtansine is an ADC comprised of a FRα-binding humanized antibody linked to the tubulin-disrupting maytansinoid DM4. This agent activates monocytes and upregulates immunogenic cell death markers on ovarian tumor cells, providing a rationale for combining with immune checkpoint blockade. Mirvetuximab soravtansine is being evaluated in combination with pembrolizumab in patients with PROC.

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

ABOUT IMMUNOGENImmunoGen 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.” Our lead product candidate, mirvetuximab soravtansine, is in a Phase 3 study for folate receptor alpha (FRα)-positive platinum resistant ovarian cancer, and in Phase 1b/2 testing in combination regimens. Our novel IGN candidates for hematologic malignancies, IMGN779 and IMGN632, are in Phase 1 studies.

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

KEYTRUDA® is a registered trademark of Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.

This press release includes forward-looking statements based on management's current expectations. These statements include, but are not limited to, ImmunoGen's ability to expand the addressable patient population for mirvetuximab soravtansine and the regulatory and commercial potential of mirvetuximab combinations in earlier lines of therapy. 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. It should be noted that there are risks and uncertainties related to the development of novel anticancer products, including risks related to preclinical and clinical studies, their timings and results, and the potential that earlier clinical studies may not be predictive of future results. A review of these risks can be found in ImmunoGen's Annual Report on Form 10-K for the year ended December 31, 2017 and other reports filed with the Securities and Exchange Commission.

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INVESTOR RELATIONS CONTACTImmunoGen, Inc.Sarah Kiely, [e-mail] CONTACTImmunoGen, Inc.Courtney O’Konek, [e-mail] ConsultingRobert Stanislaro, [e-mail]