Mirvetuximab Soravtansine in Platinum-Sensitive Ovarian Cancer

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Kathleen N. Moore, MD, of Stephenson Cancer Center, The University of Oklahoma, and colleagues found that mirvetuximab soravtansine (also known as IMGN853)—an antibody-drug conjugate targeting folate receptor alpha (FRα)—is active in FRα-positive platinum-resistant ovarian cancer, according to a phase I expansion cohort study reported in the Journal of Clinical ­Oncology.

In the study, 46 patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer received mirvetuximab soravtansine at 6.0 mg/kg (adjusted ideal body weight) once every 3 weeks. Patients had to be FRα-positive on immunohistochemistry, defined as ≥ 25% of tumor cells with ≥ 2+ staining intensity.

Response Rates and Adverse Events

Among all patients, the confirmed objective response rate was 26%, including a complete response in 1 patient and a partial response in 11 patients; the median progression-free survival was 4.8 months; and the median duration of response was 19.1 weeks. Among 23 patients with ≤ 3 prior lines of therapy, the objective response rate was 39%, the median progression-free survival was 6.7 months, and the median duration of response was 19.6 weeks.

The most common treatment-related adverse events of any grade were diarrhea (44%), blurred vision (41%), nausea (37%), and fatigue (30%). Grade 3 fatigue and grade 3 hypotension each occurred in 2 patients (4%), with no other grade 3 event occurring in > 1 patient.

The investigators concluded: “IMGN853 [mirvetuximab soravtansine] exhibited a manageable safety profile and was active in platinum-resistant ovarian cancer, with the strongest signals of efficacy observed in less heavily pretreated individuals. On the basis of these findings, the dose, schedule, and target population were identified for a phase III trial of IMGN853 monotherapy in patients with platinum-resistant ­disease.”

The study was supported by ImmunoGen.

Moore KN, et al: J Clin Oncol. December 28, 2016 (early release online).