ImmunoGen’s Elahere Aces Confirmatory Trial, Poised to Win Full Approval

ImmunoGen President and CEO Mark Enyedy/Courtesy ImmunoGen

Pictured: ImmunoGen President and CEO Mark Enyedy/Courtesy ImmunoGen

Wednesday, Massachusetts-based ImmunoGen released topline data showing its antibody-drug conjugate Elahere (mirvetuximab soravtansine-gynx) met its primary outcome in the Phase III confirmatory MIRASOL trial, inducing significant improvements in progression-free and overall survival in platinum-resistant ovarian cancer.

With these data, ImmunoGen will file a supplemental Biologics License Application with the FDA to seek full approval for Elahere during the second half of 2023, ImmunoGen CEO Mark Enyedy said during an investor call on Wednesday.

The antibody-drug conjugate won the regulator’s nod in November 2022 under the accelerated pathway for ovarian, fallopian tube or primary peritoneal cancer patients who had received one to three previous lines of systemic therapies. ImmunoGen will also file a Marketing Authorization Application for approval in Europe later this year.

“MIRASOL is a home run,” Enyedi said during Wednesday’s call, pointing out that Elahere satisfied not only its primary endpoint, but also demonstrated significant benefit in treatment response and overall survival. “Simply put, Elahere is the first medicine to demonstrate a survival benefit in this patient population,” he added.

MIRASOL enrolled 453 ovarian cancer patients who had undergone one to three prior lines of therapy, were resistant to platinum chemotherapy, and were positive for folate receptor alpha expression. Participants were randomized to receive either Elahere or an investigator’s choice of single-agent chemotherapy, which could include weekly paclitaxel, pegylated liposomal doxorubicin or topotecan.

Compared with chemotherapy, Elahere led to a significant and clinically meaningful 35% drop in the risk of disease progression or death. Median progression-free survival in Elahere participants was 5.62 months, as opposed to only 3.98 months in counterparts who received standard chemotherapy.

Elahere also induced a clinically meaningful improvement in overall survival, cutting the risk of death by 33% relative to the chemotherapy comparator. This effect was statistically significant, according to ImmunoGen’s announcement.

Objective response rate, as assessed by the MIRASOL investigator, was also higher in the Elahere arm at 42.3% with 12 complete responses, as opposed to only 15.9% in the chemotherapy group, which saw no complete responders.

As for safety, Elahere’s side effects consisted predominantly of low-grade ocular and gastrointestinal events. Treatment-emergent adverse events that were grade three or higher or led to study discontinuation, as well as serious toxicities, were all less frequent in the Elahere arm.

Still, under its current approval status, the antibody-drug conjugate’s label carries a boxed warning for severe ocular toxicities, such as visual impairment, dry eye, photophobia, eye pain and uveitis. The label also warns prescribers of pneumonitis, peripheral neuropathy and embryo-fetal toxicity.

Tristan Manalac is an independent science writer based in metro Manila, Philippines. He can be reached at or

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