ImmunoGen, Inc. announced that the first patient has been dosed in FORWARD I, the Company’s Phase 3 clinical trial evaluating mirvetuximab soravtansine as a single-agent therapy for the treatment of platinum-resistant ovarian cancer. Mirvetuximab soravtansine is a first-in-class, folate receptor alpha (FRa)-targeting ADC. FORWARD I is a Phase 3 trial in which 333 patients will be randomized 2:1 to receive either mirvetuximab soravtansine or the physician’s choice of single-agent chemotherapy (pegylated liposomal doxorubicin, topotecan, or weekly paclitaxel). Eligible patients will have been diagnosed with platinum-resistant ovarian cancer that expresses medium or high levels of FRa and will have been treated with up to three prior regimens. The primary endpoint of this study is progression free survival (PFS), which will be assessed in the entire study population and in the subset of patients with high FRa expression. ImmunoGen estimates that 12,000-14,000 patients per year in the U.S. meet these criteria, with a comparable number in the major markets in Europe.