As reported in the Journal of Clinical Oncology by Ursula A. Matulonis, MD, and colleagues, results from the phase II SORAYA study showed activity of mirvetuximab soravtansine-gynx, an antibody-drug conjugate targeting folate receptor alpha (FRα), in patients with platinum-resistant ovarian cancer and high FRα expression.

The study supported the November 2022 accelerated approval of the agent for treatment of patients with FRα-positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer who have received one to three prior systemic treatments.

Ursula A. Matulonis, MD

Study Details

In the study, 106 patients from sites in 11 countries were enrolled between June 2020 and May 2021 and received mirvetuximab soravtansine at 6 mg/kg every 3 weeks until progressive disease or unacceptable toxicity. Patients had to have received one to three prior therapies, including bevacizumab. About 51% of patients had received three prior lines of therapy, and 48% had received prior poly (ADP-ribose) polymerase (PARP) inhibitor treatment. 

The primary endpoint was investigator-assessed confirmed objective response rate.

Responses

Median follow-up was 13.4 months. Among 105 patients evaluable for response, objective response was observed in 34 patients (32.4%, 95% confidence interval [CI] = 23.6%–42.2%), including complete response in 5 (4.8%). An additional 48 patients (45.7%) had stable disease. The disease control rate (including objective responses and stable disease of ≥ 12 weeks) was 51.4%. A total of 75 patients (71.4%) exhibited tumor reduction.

Median duration of response was 6.9 months (95% CI = 5.6–9.7 months). Median progression-free survival was 4.3 months (95% CI = 3.7–5.2 months). Median overall survival was 13.8 months (95% CI = 12.0 months to not reached) with 46% of events reported.

Objective response rates were 35.3% (95% CI = 22.4%–49.9%) among patients with one or two prior lines of therapy, 30.2% (95% CI = 18.3%–44.3%) among those with three prior lines, 38.0% (95% CI = 24.7%–52.8%) among those with prior PARP inhibitor treatment, and 27.5% (95% CI = 15.9%–41.7%) among those who had not received prior PARP inhibitor treatment.

Among 96 patients assessed by blinded independent review committee, objective response was observed in 29 (30.2%, 95% CI = 21.3%–40.4%), with compete response in 6 (6.3%). Median response duration was not reached (95% CI = 5.0 months to not reached). Median progression-free survival was 5.5 months (95% CI = 3.8–6.9 months).

Adverse Events

Among 106 patients in the safety population, the most common treatment-related adverse events of any grade were blurred vision (41%), keratopathy (29%), nausea (29%), and dry eye (25%). Treatment-related grade 3 or 4 adverse events occurred in 29% of patients (grade 4 in 1%), with the most common being keratopathy (9%) and blurred vision (6%). Treatment-related peripheral neuropathy occurred in 18% of patients (all grade 1 or 2).

Serious treatment-related adverse events occurred in 11% of patients. Treatment-related adverse events led to dose delay, dose reduction, and treatment discontinuation in 33%, 20%, and 9% of patients, respectively.

The investigators concluded, “Mirvetuximab soravtansine demonstrated consistent clinically meaningful antitumor activity and favorable tolerability and safety in patients with FRα-high platinum-resistant ovarian cancer who had received up to three prior therapies, including bevacizumab, representing an important advance for this biomarker-selected population.”

Dr. Matulonis, of Dana-Farber Cancer Institute, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was funded by ImmunoGen, Inc. For full disclosures of the study authors, visit ascopubs.org.