ImmunoGen Announces Mature Data from FORWARD II Study Evaluating Mirvetuximab Soravtansine in Combination with Avastin® in Recurrent Ovarian Cancer, Regardless of Platinum Status

Rhea-AI Summary

ImmunoGen Inc. (Nasdaq: IMGN) announced mature data from the FORWARD II study, evaluating the combination of mirvetuximab soravtansine and Avastin® in recurrent ovarian cancer patients. The data will be presented at the 2021 ASCO Virtual Annual Meeting. Notably, the combination achieved a 64% overall response rate (ORR) in patients with high folate receptor alpha expression. The study included 60 patients, revealing a median duration of response of 11.8 months and a median progression-free survival of 10.6 months in high FRα patients. These findings underscore the potential of mirvetuximab as a viable treatment option.

Positive

• 64% overall response rate (ORR) in high FRα recurrent ovarian cancer.
• Median duration of response (mDOR) of 11.8 months in patients with high FRα.
• Median progression-free survival (mPFS) of 10.6 months in high FRα patients.
• Promising anti-tumor activity and favorable tolerability profile.

Negative

• Reported adverse events included diarrhea (62%), blurred vision (60%), fatigue (60%), and nausea (57%).
• Grade 3+ events included hypertension (17%) and neutropenia (13%).

ImmunoGen Inc. (Nasdaq: IMGN), a leader in the expanding field of antibody-drug conjugates (ADCs) for the treatment of cancer, today announced mature data from the FORWARD II study evaluating mirvetuximab soravtansine in combination with Avastin^® (bevacizumab) in patients with medium and high folate receptor alpha (FRα)-expressing recurrent ovarian cancer for whom a non-platinum based combination regimen is appropriate. These findings will be highlighted in an oral presentation at the 2021 American Society of Clinical Oncology (ASCO) Virtual Annual Meeting, which is being held June 4-8, 2021. Two posters highlighting mirvetuximab combination regimens will also be presented by ImmunoGen’s collaborators during the meeting.

"Due to the introduction of effective maintenance therapies, patients with recurrent ovarian cancer are living longer and comprise an increasing population in need of effective, well-tolerated non-platinum based regimens," said Anna Berkenblit, MD, Senior Vice President and Chief Medical Officer of ImmunoGen. "With a 64% ORR, 11.8 month mDOR, and 10.6 month mPFS, the combination of mirvetuximab plus bevacizumab shows compelling activity in patients with high FRα recurrent ovarian cancer. We are extremely pleased to present these data during an oral presentation at ASCO, as they build on previous findings and provide us with further evidence of mirvetuximab's potential to become the combination agent of choice for ovarian cancer patients."

MATURE DATA FROM FORWARD II DOUBLET COHORT WITH BEVACIZUMAB

The cohort enrolled 60 patients with a median age of 60 and a median number of 2 prior lines of therapy (range 1-4). 53% had platinum-resistant disease with a platinum-free interval (PFI) of less than or equal to 6 months; 33% had partially platinum-sensitive disease with a PFI greater than 6 months and less than or equal to 12 months; and 13% had a PFI greater than 12 months. 40% of patients in the cohort were previously treated with bevacizumab and 35% of patients in the cohort were previously treated with a PARP inhibitor. The combination of mirvetuximab with bevacizumab in this cohort demonstrates promising anti-tumor activity with a favorable tolerability profile, particularly among patients with high levels of FRα expression, and is encouraging relative to outcomes with available therapies reported in similar populations. In the oral presentation, key updated data include:

• In the overall patient population, objective responses were seen in 30 patients and the confirmed overall response rate (ORR) was 50% (95% CI, 34, 60), with a median duration of response (mDOR) of 9.7 months (95% CI 6.7, 12.9) and median progression-free survival (mPFS) of 8.3 months (95% CI 5.6, 10.1).
• In patients with high FRα expression (n=33), the confirmed ORR was 64% (95% CI, 45, 80), mDOR was 11.8 months (95% CI 6.7, 13.7), and mPFS was 10.6 months (95% CI 8.3, 13.3).
  • In high FRα platinum-sensitive patients, who represent a growing population, the combination of mirvetuximab plus bevacizumab achieved a 69% ORR, 12.7 month mDOR, and a 13.3 month mPFS.
  • In high FRα platinum-resistant patients, the combination of mirvetuximab plus bevacizumab achieved a 59% ORR, 9.4 month mDOR, and a 9.7 month mPFS.
• The adverse events (AEs) observed with the doublet were manageable and consistent with the side effect profiles of each agent. Treatment-related AEs were generally low grade, with diarrhea (62%), blurred vision (60%), fatigue (60%), and nausea (57%) being the most common. The most common grade 3+ events were hypertension (17%) and neutropenia (13%).

"Despite advances in the maintenance setting of ovarian cancer, a high unmet need for novel, well-tolerated, targeted treatments exists in those patients with recurrent high-grade epithelial ovarian cancer," said David O'Malley, MD, Professor, Director of Gynecologic Oncology and Co-Director, Gynecologic Oncology Phase 1 Program at The Ohio State University and the James Cancer Center, and FORWARD II Principal Investigator. "The data we continue to see when mirvetuximab is combined with bevacizumab in recurrent disease are extremely encouraging, particularly in light of outcomes reported with available therapies in even less heavily pre-treated populations. The strength of these mature data warrant further development of this novel, targeted combination and I look forward to evaluating this regimen in earlier lines of therapy."

ORAL PRESENTATION SESSION

• Title: "Mirvetuximab Soravtansine, a Folate Receptor Alpha-Targeting Antibody-Drug Conjugate, in Combination with Bevacizumab in Patients with Platinum-Agnostic Ovarian Cancer - Final Analysis"
• Day/Time: Monday, June 7 from 8:00 a.m. to 11:00 a.m. ET
• Lead Author: David M. O'Malley, MD, The Ohio State University College of Medicine
• Abstract: 5504

POSTER SESSIONS

The following posters will be available on Friday, June 4 at 9:00 a.m. ET in the ASCO Meet

FAQ

What are the latest findings from ImmunoGen regarding mirvetuximab and Avastin?

ImmunoGen reported a 64% overall response rate from the FORWARD II study combining mirvetuximab with Avastin in high FRα recurrent ovarian cancer patients.

What is the significance of the FORWARD II study data for ImmunoGen (IMGN)?

The FORWARD II study data highlights the effectiveness of mirvetuximab with a median duration of response of 11.8 months and progression-free survival of 10.6 months, reinforcing its potential in treating recurrent ovarian cancer.

When will ImmunoGen present the FORWARD II study results?

The results from the FORWARD II study will be presented during the 2021 ASCO Virtual Annual Meeting, specifically on June 7.

How many patients were involved in the FORWARD II study?

The FORWARD II study involved 60 patients with recurrent ovarian cancer.

What is the overall response rate for patients treated with mirvetuximab and Avastin?

In patients with high FRα expression, the overall response rate was reported at 64%.