ImmunoGen Shares Rally After Ovarian Cancer Trial Meets Primary Endpoint Goal

ImmunoGen Inc IMGN shares have gained more than 30% during premarket trading in reaction to positive topline data from the SORAYA trial of mirvetuximab soravtansine for ovarian cancer.

• The trial is evaluating mirvetuximab as monotherapy in patients with folate receptor alpha (FRα)-high platinum-resistant ovarian cancer who have been previously treated with Roche Holdings AG's RHHBY Avastin (bevacizumab).
• SORAYA study enrolled 106 patients with a median of three prior lines of therapy.
• The investigator's objective response rate (ORR) was 32.4%, including five complete responses (CRs), meeting the primary endpoint. ORR by BICR was 31.6%, including five CRs. 
• Responses were observed regardless of prior PARP inhibitor or the number of prior lines of therapy.
• The median Duration of Response (DOR) is 5.9 months. With nearly half of responders continuing on therapy, median DOR could range from 5.7 to just above 7 months. Mirvetuximab was well-tolerated. 
• Treatment-related adverse events led to dose reductions in 19% of patients, dose delays in 32% of patients, and discontinuations in 7% of patients. 
• The marketing submission for mirvetuximab is on track for Q1 2022.
• Beyond SORAYA, Immunogen expects to generate topline data from confirmatory MIRASOL trial in Q3 of 2022 to support the potential full approval of mirvetuximab.
• Price Action: IMGN shares are up 30.3% at $6.19 during the premarket session on the last check Tuesday.