BLA Submitted for Mirvetuximab Soravtansine in Ovarian Cancer

ImmunoGen, Inc has submitted a Biologics License Application (BLA) to the FDA under the accelerated approval pathway for mirvetuximab soravtansine (IMGN853) monotherapy for patients with folate receptor alpha (FRα)-high platinum-resistant ovarian cancer previously treated with 1 to 3 prior systemic treatments. The drug is a first-in-class antibody-drug conjugate comprised of a folate receptor alpha-binding antibody, cleavable linker, and the maytansinoid payload DM4 to attack targeted cancer cells, according to ImmunoGen.¹

The BLA was based on findings from the phase 3 SORAYA trial presented at the Society of Gynecologic Oncology (SGO) 2022 Annual Meeting. The FDA now has a 60-day review period to evaluate the BLA. ImmunoGen said that it has requested FDA priority review, which if granted, will be completed within 6 months of the filing date.

“The BLA submission for mirvetuximab soravtansine is a key inflection point on our journey to delivering a safe and effective treatment option to patients with platinum-resistant ovarian cancer and moves us one step closer to transforming ImmunoGen into a fully-integrated oncology company,” said Mark Enyedy, ImmunoGen president and chief executive officer, in a press release. “Platinum-resistant ovarian cancer is an area with high unmet need, and we look forward to working with FDA to secure mirvetuximab soravtansine’s first approval and bringing this novel therapy to patients as quickly as possible.”

Data presented at the SGO meeting show that the use of mirvetuximab soravtansine monotherapy in patients with ovarian cancer resulted in meaningful anti-tumor activity, consistent safety, and favorable tolerability.²

The single-arm SORAYA trial enrolled 106 patients with a median of 3 prior lines of therapy. Specifically, 51% had 3 prior lines of therapy and 48% had 1 to 2 prior lines of therapy. All patients received prior bevacizumab and 48% had received a prior poly (ADP-ribose) polymerase (PARP) inhibitor.

The confirmed overall response rate (ORR) was 32.4% among patients receiving mirvetuximab soravtansine, including 5 patients with complete responses. ORR by blinded independent central review was 31.6%, including 5 complete responses. These response rates were consistent regardless of the number of prior lines of therapy or prior PARP inhibition.

Patients administered 1 to 2 prior lines of therapy had a 35.3% ORR when assessed by investigators and patients with 3 prior lines of therapy had a 30.2% ORR. Patients with prior PARP inhibitor exposure had an ORR of 38% when assessed by investigator, whereas those without prior PARP inhibitor exposure had a response rate of 27.5%.

Furthermore, the median duration of response was 6.9 months as of the March 3, 2022, data cut-off. The median progression-free survival was 4.3 months by investigator and 5.5 months by blinded independent central review.

Mirvetuximab was well-tolerated and findings were consistent with the known safety profile seen in more than 700 patients treated in the broader mirvetuximab program.

ImmunoGen continues to enroll patients in the confirmatory MIRASOL trial to produce the randomized data needed for full approval of the drug, top-line data from this study expected to be released in the third quarter of 2022.

“We are thrilled with the SORAYA results, which are remarkably consistent with data previously generated with mirvetuximab in a heavily pre-treated population of platinum-resistant ovarian cancer patients that included prior exposure to bevacizumab,” said Anna Berkenblit, MD, senior vice president and chief medical officer of ImmunoGen, in the press release. “Based on the impressive anti-tumor activity, durability of response, and safety profile observed in SORAYA, we believe mirvetuximab has the potential to displace single-agent chemotherapy as the standard of care for FRα-high platinum-resistant ovarian cancer.”

The FDA granted mirvetuximab soravtansine Fast Track Designation in June 2018 for patients with medium to high FRα-positive platinum-resistant ovarian cancer who received at least 1, but no more than 3, previous systemic treatment regimens, and for whom single-agent chemotherapy is appropriate as the next line of therapy.

References

1. ImmunoGen submits biologics license application to the US Food and Drug Administration for mirvetuximab soravtansine in ovarian cancer. News release. ImmunoGen, Inc.; March 29, 2022. Accessed March 29, 2022. https://investor.immunogen.com/news-releases/news-release-details/immunogen-submits-biologics-license-application-us-food-and-drug

2. ImmunoGen Presents Full Results from Positive Pivotal SORAYA Trial of Mirvetuximab Soravtansine in Ovarian Cancer at SGO Annual Meeting. News release. Immunogen; March 19, 2022. https://investor.immunogen.com/news-releases/news-release-details/immunogen-presents-full-results-positive-pivotal-soraya-trial