Positive Response Rates Observed With Mirvetuximab Soravtansine for Platinum-Resistant Ovarian Cancer

Positive top-line data were seen from the phase 3 SORAYA trial (NCT04296890), investigating both the safety and efficacy of mirvetuximab soravtansine (IMGN853) monotherapy in patients with folate receptor α (FRα)–high platinum-resistant ovarian cancer who previously received bevacizumab (Avastin), according to a press release from ImmunoGen.

The confirmed overall response rate (ORR) as assessed by investigators was 32.4% (95% CI, 23.6%-42.2%) for patients treated with mirvetuximab soravtansine and included 5 complete responses (CRs). ORR as analyzed by blinded independent central review (BICR) was 31.6% (95% CI, 22.4%-41.9%), with 5 CRs observed. Responses took place regardless of prior treatment with PARP inhibitors or number of lines of therapy.

“Despite advances in the platinum-sensitive setting, most patients with ovarian cancer eventually develop platinum-resistant disease, for which there are limited treatment options, especially for those patients who have previously received bevacizumab,” co-principal investigator Robert Coleman, MD, chief scientific officer of U.S. Oncology Research at ImmunoGen, said in a press release. “Data from SORAYA have the potential to redefine the standard of care for patients with FRα-high platinum-resistant ovarian cancer, as this trial has demonstrated that mirvetuximab delivers clinically meaningful benefit in this setting, with significant and durable responses and a favorable tolerability profile.”

The single-arm study included patients with platinum-resistant ovarian cancer who had tumors expressing high levels of FRα. Patients received up to 3 prior treatments, 1 of which needed to include bevacizumab.

The primary end point of the SORAYA trial was investigator-assessed confirmed ORR, with key secondary end points including duration of response (DOR), ORR assessed by BICR, and safety.

A total of 106 patients were enrolled on the study who had received a median 3 previous lines of therapy (range, 1-4). Forty-eight percent of patients in the population previously received a PARP inhibitor. The study had a data cutoff on November 16, 2021 and had a median follow-up time of 8.1 months.

Investigators reported a median DOR of 5.9 months (95% CI, 5.6-7.7). Because nearly half of the responders continue therapy and the DOR is still evolving, investigators suggested that the DOR could range from 5.7 to over 7 months with longer-term follow-up.

In terms of safety, mirvetuximab soravtansine was well tolerated in the trial and was similar to the known safety profile seen in over 700 patients treated with the drug. Dose reductions due to treatment-related adverse effects (TRAEs) were seen in 19% of patients. TRAEs led to dose delays and discontinuations in 32% and 7% of patients, respectively. Common any grade TRAEs included blurred vision (41%), keratopathy (35%), and nausea (29%). Grade 3 or higher TRAEs included blurred vision (6%) and keratopathy (9%).

ImmunoGen anticipates submitting the Biologics License Application (BLA) to the FDA for mirvetuximab soravtansine in the first quarter of 2022.

“These data have the potential to be transformative for [patients with] ovarian cancer and their physicians,” co-principal investigator, Ursula Matulonis, MD, chief of the Division of Gynecologic Oncology at Dana-Farber Cancer Institute and professor of medicine at Harvard Medical School, said. “With an ORR above 30%, a duration of response of around six months, and a treatment-related discontinuation rate below 10%, mirvetuximab shows impressive activity and tolerability for patients with platinum-resistant ovarian cancer. If approved, mirvetuximab will become a critical therapeutic option for patients with FRα-high ovarian cancer.”

Reference

ImmunoGen announces positive top-line results from pivotal SORAYA trial of mirvetuximab soravtansine in ovarian cancer. News release. ImmunoGen. November 30, 2021. Accessed November 30, 2021. https://tinyurl.com/yckv6d5d