Why Are ImmunoGen Shares Trading Lower Today

ImmunoGen Inc IMGN shared full results from the SORAYA trial evaluating mirvetuximab in folate receptor alpha (FRα)-high platinum-resistant ovarian cancer patients, previously treated with Roche Holdings AG's RHHBY Avastin (bevacizumab). 

• The results were shared at the Society of Gynecologic Oncology (SGO) 2022 Annual Meeting.
• SORAYA enrolled 106 patients with a median of three prior lines of therapy.
• Related: ImmunoGen Shares Rally After Ovarian Cancer Trial Meets Primary Endpoint Goal.
• Confirmed objective response rate (ORR) by the investigator was 32.4%, including five complete responses (CRs). ORR by BICR was 31.6%, including five CRs. 
• The median duration of response (DOR) was 6.9 months. The investigator's median progression-free survival (PFS) was 4.3 months and 5.5 months by BICR.
• Read Next: Lilly Unites With ImmunoGen In ADC Deal Worth Up To $1.7B.
• Analyst Reaction: RBC Capital downgraded ImmunoGen to Sector Perform from Outperform with a price target of $6, down from $9, after the full data from Mirvetuximab Soravtansine's Phase 3 SORAYA trial.
• Analyst Kennen MacKay sees Mirvetuximab's median PFS of 4.3 months as adding "clinical meaningfulness" questions and suggesting substantial risk to the confirmatory MIRASOL trial and regulatory proceeding. 
• MacKay reduced the Mirvetuximab's probability of success estimates to 50% from 85%.
• Price Action: IMGN shares are down 18.1% at $4.31 during the premarket session on the last check Monday.