ELAHERE Demonstrates Overall Survival Benefit in the Phase 3 MIRASOL Trial in Patients with FRα-Positive Platinum-Resistant Ovarian Cancer

ImmunoGen Inc. (Nasdaq: IMGN), a leader in the expanding field of antibody-drug conjugates (ADCs) for the treatment of cancer, today announced positive top-line data from the Phase 3 confirmatory MIRASOL trial (GOG 3045/ENGOT OV-55) evaluating the safety and efficacy of ELAHERE (mirvetuximab soravtansine-gynx) compared to chemotherapy in patients with folate receptor alpha (FRα)-positive platinum-resistant ovarian cancer who have received one to three prior lines of therapy. Based on these data, the Company plans to submit a Marketing Authorization Application (MAA) in Europe and a supplemental Biologics License Application (sBLA) in the US for the conversion to a regular approval of ELAHERE.

"I believe the data from the confirmatory MIRASOL trial are practice-changing. They demonstrate ELAHERE's superiority to chemotherapy based on all efficacy endpoints, in particular overall survival, and build on the clinical benefit of ELAHERE previously reported in the SORAYA trial," said Kathleen Moore, Associate Director of Clinical Research and Director of the Oklahoma TSET/Sarah Cannon Phase I Program, Professor of the Section of Gynecologic Oncology at The University of Oklahoma and MIRASOL Principal Investigator. "Last year's accelerated approval of ELAHERE was a paradigm-shifting development in the treatment landscape for this disease and I am confident that, with the MIRASOL data, ELAHERE has the potential to become the new standard of care for patients with FRα-positive, platinum-resistant ovarian cancer. FRα status is a 'must know' for all ovarian cancer patients and, for those with platinum-resistant disease who test positive, I believe ELAHERE should be their first treatment option."

MIRASOL (NCT04209855) is a randomized Phase 3 trial of ELAHERE versus investigator's choice (IC) of single-agent chemotherapy (weekly paclitaxel, pegylated liposomal doxorubicin, or topotecan). Eligibility criteria include patients with platinum-resistant ovarian cancer whose tumors express high levels of FRα, using the Ventana FOLR1 Assay, and who have been treated with up to three prior regimens. The primary endpoint of this trial is progression-free survival (PFS) by investigator assessment. Key secondary endpoints include objective response rate (ORR) and overall survival (OS).