Pivotal Trial Supports Use of Mirvetuximab Soravtansine in Ovarian Cancer

Use of mirvetuximab soravtansine monotherapy in patients with ovarian cancer resulted in meaningful anti-tumor activity, consistent safety, and favorable tolerability.

New data released at the Society of Gynecologic Oncology (SGO) 2022 Annual Meeting on Women’s Cancer show that the use of mirvetuximab soravtansine monotherapy in patients with ovarian cancer resulted in meaningful anti-tumor activity, consistent safety, and favorable tolerability.

Based on these data, ImmunoGen plans to submit a Biologics License Application to the FDA later this month, according to a press release. The results come from the pivotal SORAYA trial evaluating mirvetuximab soravtansine monotherapy in adults with folate receptor alpha-high platinum-resistant ovarian cancer who were previously treated with bevacizumab.

“Patients with platinum-resistant ovarian cancer have limited treatment options, and these are associated with low response rates and significant toxicity,” said Ursula Matulonis, MD, co-principal investigator in the SORAYA trial and presenter of the data at the SGO meeting. “With an objective response rate of 32.4%, far exceeding that seen with current therapies, and a median duration of response approaching 7 months, mirvetuximab continues to demonstrate impressive efficacy in patients with platinum-resistant disease who have already received bevacizumab.”

SORAYA is a single-arm study of mirvetuximab with the primary endpoint of confirmed objective response rate and a key secondary endpoint of duration of response. The 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.

“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.”

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. Treatment-related adverse events led to dose reductions in 19% of study participants, dose delays in 32% of patients, and discontinuation in 7% of patients. The most common treatment-related adverse events were low-grade and generally reversible, and included blurred vision, keratopathy, and nausea.

“The anti-tumor activity and consistent safety and tolerability data from the SORAYA trial further underscore the potential of mirvetuximab, if approved, to become a practice-changing, biomarker-driven standard of care for these patients,” Matulonis said in the press release.

REFERENCE

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. Accessed March 19, 2022. https://investor.immunogen.com/news-releases/news-release-details/immunogen-presents-full-results-positive-pivotal-soraya-trial