FDA bestows accelerated approval on ImmunoGen's ovarian cancer drug, with confirmatory answer coming soon
Three and a half years ago, ImmunoGen ran up against an FDA brick wall. Its ovarian cancer drug, mirvetuximab soravtansine, failed a Phase III study, forcing the biotech to scale back and lay off more than two-thirds of its staff. Execs tightened their belts to preserve the cash they had left.
And Monday, after shepherding the program through another pivotal trial, the move appeared to pay off.
The FDA approved ImmunoGen’s drug Monday afternoon, capping the turnaround after the biotech slashed its staff from about 300 to 80. The antibody-drug conjugate, which will be branded as Elahere, is the US’ first new treatment for advanced ovarian cancer in at least seven years. Elahere comes with a black box warning for ocular toxicity.
Pricing information was not immediately available, but an ImmunoGen spokesperson told Endpoints News management will unveil the price during an investor call Tuesday morning. This story will be updated accordingly. ImmunoGen shares $IMGN rose 12% pre-market.
ImmunoGen won an accelerated approval here, with the Phase III trial showing enough reduction in tumor shrinkage to merit a green light. The confirmatory study, which ImmunoGen says is already fully enrolled, is expected to read out topline data early next year. As part of Monday’s approval, ImmunoGen also submitted initial confirmatory data to the FDA.
Additionally, that trial is not double-blinded, but rather an open-label comparison of Elahere and investigator’s choice of chemotherapy. The primary endpoint of the study is progression-free survival.
As with all accelerated approvals, the FDA decision is contingent on the confirmatory data. Regulators have tried to crack down recently on dangling accelerated approvals, where the drugs are left on the market despite confirmatory fails. Some analysts see a small chance Elahere could fall into this category.
SVB’s Jonathan Chang estimates a 75% chance of Elahere success — pegging 64% odds the confirmatory study meets the endpoint outright, and a 30% chance the trial fails but the drug isn’t pulled.
The approval itself was based on a single-arm study showing an overall response rate of 31.7% in 106 ovarian cancer patients who’d received between one to three previous systemic treatments. Researchers saw five patients achieve a complete response and a median duration of response of 6.9 months.
Though Monday’s decision proved the capstone of a long turnaround journey, the path appeared tenuous at times. After an initial cut of data in November 2021 signaled ImmunoGen may have successfully resuscitated the drug, a deeper look disappointed the following March and sent its stock tumbling 17%.
Elahere is an antibody-drug conjugate designed to target folate receptor alpha. Between 35% and 40% of ovarian cancer patients express high levels.