Positive Topline Data From MIRASOL Supports Mirvetuximab for Patients With Platinum-Resistant Ovarian Cancer

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The novel antibody-drug conjugate is the first to demonstrate overall survival benefits in patients who were already treated with therapy.

Mirvetuximab soravtansine-gynx (mirvetuximab; Elahere, ImmunoGen), a first-in-class antibody-drug conjugate (ADC), reduced risk of death by 33% compared to chemotherapy in patients with folate receptor alpha (FRα)-positive platinum-resistant ovarian cancer (OC) who have had 1 to 3 lines of therapy, according to positive topline data from the phase 3 randomized MIRASOL (NCT04209855) study.

Further, mirvetuximab decreased risk of tumor progression or death by 35% compared to chemotherapy, showing statistically significant and clinically meaningful improvement in the primary endpointof progression-free survival (PFS).

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"Last year's accelerated approval of [mirvetuximab] was a paradigm-shifting development in the treatment landscape for this disease,” said lead investigator Kathleen Moore, associate director of clinical research and director of the Oklahoma TSET/Sarah Cannon Phase I Program and professor of the Section of Gynecologic Oncology at The University of Oklahoma, in the press release.

The ADC also had statistically significant and clinically meaningful improvement in key secondary endpoints; 42.3% of patients showing an objective response rate (ORR) and patients experienced longer overall survival (OS) compared to chemotherapy (16.46 months and 12.75 months, respectively). It is the first drug of its kind to improve OS in this patient population.

The MIRASOL study compared the safety and efficacy of mirvetuximab to an investigator’s choice (IC) of single-agent chemotherapy in 453 patients with platinum-resistant OC and high Frα expression who have had at least 1 prior line of therapy. Median PFS was 5.62 months with mirvetuximab compared to 3.98 months with chemotherapy. Among the 42.3% of patients with ORR, 12 experienced complete response (CR), with ORR of 15.9% and 0 patients experiencingCR in the IC arm.

Investigators noted they did not observe any new safety signals. The most common adverse events (AEs) were low-grade ocular and gastrointestinal symptoms. At least 42% of patients experienced a grade 3 or higher AE, with 24% experiencing serious AEs and 9% discontinuing the drug.

OC is often diagnosed at a later stage and is currently the leading cause of mortality among US gynecological cancers. The traditional route of care is surgery followed by standard of care (SOC) platinum-based chemotherapy. Unfortunately, patients often develop difficult-to-treat platinum-resistant disease that renders future single-agent chemotherapies ineffective and leaves patients with significant toxicities.

In November 2022, the FDA granted mirvetuximab accelerated approval for adults with patients with FRα-positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer who had prior treatment due to SORAYA data. ImmunoGen will submit a supplemental biologics license application (sBLA) later in 2023.

“[The data] demonstrate mirvetuximab’s superiority to chemotherapy based on all efficacy endpoints, in particular OS, and build on the clinical benefit of mirvetuximab previously reported in the SORAYA trial," Moore said in the press release.

Reference

ImmunoGen Inc. ELAHERE® Demonstrates Overall Survival Benefit in the Phase 3 MIRASOL Trial in Patients with FRα-Positive Platinum-Resistant Ovarian Cancer. News Release. May 3, 2023. Accessed on May 4, 2023. https://www.businesswire.com/news/home/20230503005305/en