Mirvetuximab Soravtansine Proves Safe and Effective in FRα-High Ovarian Cancer

Ursula A. Matulonis, MD

Mirvetuximab soravtansine (IMGN853) led to improved responses when used for patients with folate receptor alpha (FRα)-high platinum-resistant ovarian cancer, according to findings from the internationally conducted phase 3 SORAYA trial (NCT04296890) led by investigators at Dana-Farber Cancer Institute.¹

Findings showed that at a median follow-up of 13.4 months, objective anti-cancer responses were observed in 32.4% of patients, including 5 who had a complete response and 29 who had a partial response (95% CI, 23.6-42.2), and the median duration of response (DOR) was 6.9 months (95% CI, 5.6-9.7). Regarding safety, mirvetuximab was well-tolerated and the most common adverse events (AEs) included blurred vision, keratopathy, and nausea.²

As a result of these positive findings, the FDA granted accelerated approval to mirvetuximab soravtansine in November 2022.

“We’ve learned that mirvetuximab, which is an antibody drug conjugate targeting folate receptor alpha, when used as a single agent has very impressive anti-cancer activity in folate receptor alpha positive platinum resistant ovarian cancer. Platinum resistant ovarian cancer is a very tough cancer to treat, and the last drug approval for this cancer was in 2014. So, the SORAYA study which led to the accelerated approval of mirvetuximab to treat folate receptor alpha positive platinum resistant ovarian cancer is a huge step forward for our patients,” Ursula A. Matulonis, MD, chief of the Division of Gynecologic Oncology at Dana-Farber Cancer Institute, lead author and co-principal investigator of the study, told Targeted Oncology^TM.

In the SORAYA trial, 106 patients with platinum-resistant high-grade serous ovarian cancer were enrolled. Patients in the trial had previously received 1-3 therapies, including required bevacizumab (Avastin).²

Investigators evaluated the primary end point of confirmed objective response rate (ORR) and the secondary end point of DOR. Additional secondary end points included safety, progression-free survival, Gynecological Cancer InterGroup CA-125 response rate, and overall survival.

Among the 105 patients evaluable for efficacy, all patients had received prior bevacizumab, 51% received 3 prior lines of therapy, and 48% received a prior poly ADP-ribose polymerase inhibitor. The median age of patients was 62 years, all patients had high-grade serous histology, 59% had stage III disease at the time of diagnosis, and 38% had stage IV disease.

Ultimately, the study met its primary end point of ORR. In patients who had 1-2 prior lines of therapy, the ORR by investigator was 35.3% (95% CI, 22.4-49.9). Patients with 3 prior lines had an ORR of 30.2% (95% CI, 18.3-44.3). For patients with prior poly ADP-ribose polymerase inhibitor exposure, the ORR by investigator was 38.0% (95% CI, 24.7-52.8) and 27.5% (95% CI, 15.9-41.7) for patients without.

All grade and grade 3-4 treatment-related AEs included blurred vision (41% and 6%), keratopathy (29% and 9%), and nausea (29% and 0%). Treatment-related AEs resulted in dose delays in 33% of patients, reductions in 20%, and discontinuations in 9%, respectively.

“[T]he SORAYA trial demonstrated that [mirvetuximab soravtansine] monotherapy elicited high ORRs, durable responses, and a tolerable safety profile in patients with high-FRα [platinum-resistant ovarian cancer]. Activity was observed irrespective of number of previous lines of therapy received or PARP [inhibitor] exposure in patients having received prior bevacizumab. Given the lack of effective therapies and poor prognosis for patients in this setting, the findings reported here underscore the potential for [mirvetuximab soravtansine] to become a biomarker-driven, standard-of-care option in this difficult-to-treat population,” concluded study authors in findings published in the Journal of Clinical Oncology.

“The approval of mirvetuximab is very significant for patients with FRα-positive platinum-resistant ovarian cancer since there are limited treatment options with poor results, and this has been a very difficult cancer to treat. Mirvetuximab is a very important new therapeutic agent in our armamentarium to treat platinum resistant ovarian cancer,” added Matulonis.

REFERENCES:

Results of the SORAYA study show conjugate therapy produced remissions in one-third of patients with drug-resistant ovarian cancer. News Release. Dana-Farber Cancer Institute. January 30, 2023. Accessed February 1, 2023. https://bit.ly/3jkQ2Mj

Matulonis UA, Lorusso D, Oaknin A, et al. Efficacy and safety of mirvetuximab soravtansine in patients with platinum-resistant ovarian cancer with high folate receptor alpha expression: results from the SORAYA study. Published online January 30, 2023. J Clin Oncol. 2023;JCO2201900. doi:10.1200/JCO.22.01900