Press release

Mar 24, 2018
ImmunoGen Presents Data from FORWARD II Assessment of Mirvetuximab Soravtansine in Combination with Pembrolizumab at the Society of Gynecologic Oncology Annual Meeting

WALTHAM, Mass.--()--ImmunoGen, Inc. (Nasdaq: IMGN), a leader in the expanding field of antibody-drug conjugates (ADCs) for the treatment of cancer, today announced encouraging efficacy and favorable tolerability data from the FORWARD II cohort assessing mirvetuximab soravtansine in combination with Merck’s anti-PD-1 therapy pembrolizumab in patients with platinum-resistant epithelial ovarian cancer (EOC). These data are being presented at the Society of Gynecologic Oncology (SGO) Annual Meeting, March 24-27, 2018 in New Orleans, LA.

Key findings in 14 heavily pre-treated patients are as follows:

  • In the subset of 8 patients with medium or high folate receptor alpha (FRα) expression levels, the confirmed overall response rate (ORR) was 63 percent (95% CI 25, 92), with a median progression-free survival (PFS) of 8.6 months (95% CI 1.6, upper bound not yet reached).
  • For all patients, the confirmed ORR was 43 percent (95% CI 18, 71), with a median PFS of 5.2 months (95% CI 1.6, 9.5); patients in this cohort had received a median of 4.5 prior lines of systemic therapy, with 64% of patients receiving 4 or more prior lines.
  • As previously reported, at full dosing, the combination of mirvetuximab (6 mg/kg) and pembrolizumab (200 mg, supplied by Merck) demonstrates favorable tolerability, consistent with the known safety profiles of each agent, with primarily mild to moderate (≤ grade 2) adverse events observed.

Based on these data, ImmunoGen is enrolling an additional 35 patients with medium or high FRα expression levels in an expansion cohort in the FORWARD II study.

“We are encouraged by the early evidence of anti-tumor activity with durable responses and the tolerability profile of mirvetuximab in combination with pembrolizumab, particularly among the subset of patients with medium or high folate receptor alpha expression where we saw the greatest benefit,” said Anna Berkenblit, M.D., Vice President and Chief Medical Officer of ImmunoGen. “Across multiple combinations, we’ve demonstrated that our Phase 3 single agent dose level for mirvetuximab combines readily with other therapies. The consistency of these findings further underscore the potential of mirvetuximab for ovarian cancer – both as monotherapy, and in combination with other therapies in earlier lines of treatment.”

Featured Poster Presentation Details

Title: "Initial safety and activity findings from a phase 1b escalation study of mirvetuximab soravtansine, a folate receptor alpha (FRα)-targeting antibody-drug conjugate (ADC), in combination with pembrolizumab in platinum-resistant epithelial ovarian cancer (EOC) patients" (abstract #74)

Lead author: Ursula Matulonis, M.D., Director and Program Leader, Gynecologic Oncology Program, Dana-Farber Cancer Institute, Boston, MA

The findings will be presented during featured poster presentation discussion sessions:

  • Sunday, March 25 at 3:30pm CT
  • Monday, March 26 at 3:30pm CT

Additional information can be found at www.sgo.org

About FORWARD II
FORWARD II is a Phase 1b/2 study of mirvetuximab in combination with Avastin® (bevacizumab), pegylated liposomal doxorubicin, or Keytruda® (pembrolizumab) in patients with FRα-positive platinum-resistant EOC, primary peritoneal, or fallopian tube tumors, as well as a doublet combination of mirvetuximab with carboplatin and a triplet combination of mirvetuximab plus carboplatin and Avastin in patients with platinum-sensitive ovarian cancer.

About Mirvetuximab Soravtansine
Mirvetuximab soravtansine (IMGN853) is the first FRα-targeting ADC. It uses a FRα-binding antibody to target the ADC specifically to FRα-expressing cancer cells and a potent anti-tumor agent, DM4, to kill the targeted cancer cells.

About ImmunoGen, Inc.
ImmunoGen is a clinical-stage biotechnology company that develops targeted cancer therapeutics using its proprietary ADC technology. The Company’s lead product candidate, mirvetuximab soravtansine, is in the Phase 3 FORWARD I trial for FRα-positive platinum-resistant ovarian cancer, and is in the Phase 1b/2 FORWARD II trial in combination regimens for earlier-stage disease. ImmunoGen has three additional clinical-stage product candidates, two of which are being developed in collaboration with Jazz Pharmaceuticals. ImmunoGen's ADC technology is also used in Roche's marketed product, Kadcyla®, and in programs in development by Amgen, Bayer, Biotest, CytomX, Debiopharm, Lilly, Novartis, Sanofi and Takeda. More information about the Company can be found at www.immunogen.com.

Keytruda®, Avastin® and Kadcyla® are registered trademarks of their respective owners.

This press release includes forward-looking statements. 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. It should be noted that there are risks and uncertainties related to the development of novel anticancer products, including mirvetuximab soravtansine, and risks related to preclinical and clinical studies, their timings and 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.

Contacts

For Investors
ImmunoGen, Inc.
Sarah Kiely, 781-895-0600
sarah.kiely@immunogen.com
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ImmunoGen, Inc.
Courtney O’Konek, 781-895-0600
courtney.okonek@immunogen.com
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Robert Stanislaro, 212-850-5657
robert.stanislaro@fticonsulting.com