FDA Grants Priority Review to Mirvetuximab Soravtansine for FRα-High, Platinum-Resistant Ovarian Cancer

The FDA has accepted and filed a biologics license application (BLA) for mirvetuximab soravtansine (IMGN853) for the treatment of patients with folate receptor alpha (FRα)–high, platinum-resistant ovarian cancer who have previously received between 1 and 3 systemic therapies.¹ The application simultaneously received priority review designation.

The BLA, which is based on findings from the pivotal phase 3 SORAYA trial (NCT04296890), seeks approval of mirvetuximab soravtansine under the accelerated approval pathway. The regulatory agency is scheduled to decide on the application by November 28, 2022, under the Prescription Drug User Fee Act.

“FDA’s acceptance of our BLA under priority review reinforces our belief in the potential for mirvetuximab soravtansine to serve as a new standard of care for patients with FRα-high platinum-resistant ovarian cancer,” Mark Enyedy, president and chief executive officer of ImmunoGen said in a press release. “We are pleased to be one step closer to realizing the promise of our technology and are working closely with FDA to support the evaluation of our application. We are moving quickly to build out the commercial and medical infrastructure required for a successful launch and look forward to the prospect of delivering mirvetuximab soravtansine to patients later this year.”

The global, single-arm SORAYA trial enrolled 106 patients with platinum-resistant ovarian cancer whose tumors expressed high levels of FRα and who had been treated with up to 3 prior regimens, at least 1 of which included bevacizumab (Avastin).

Study participants received intravenous mirvetuximab soravtansine at 6 mg/kg once every 3 weeks. The primary end point was confirmed investigator-assessed objective response rate (ORR), and the key secondary end point was duration of response (DOR). ORR was also assessed by blinded independent central review (BICR).

In the overall population, the median age was 62 years (range, 35-85). Fifty-one percent of patients had received a median of 3 prior lines of therapy (range, 1-4), and 48% had received a prior PARP inhibitor.

The study was designed to rule out a 12% ORR, based on expected outcomes with available single-agent chemotherapy from the AURELIA trial (NCT00976911), which was done in patients with platinum-resistant ovarian cancer who had received 1 or 2 prior lines of therapy.

Top-line data from SORAYA, which were announced in November 2021,² indicated that the trial met its primary end point, with an investigator-assessed ORR of 32.4% (95% CI, 23.6%-42.2%) in the overall efficacy population. At a median follow-up of 8.1 months, the median DOR was 5.9 months (95% CI, 5.6-7.7).

Full data from the study, which were presented during the 2022 SGO Annual Meeting,³ demonstrated that among the 34 responders, 5 patients achieved a complete response (CR), and 29 experienced a partial response (PR). At a data cutoff of November 16, 2021, the median investigator-assessed DOR was 6.9 months (95% CI, 5.6-8.1), and the median progression-free survival was 4.3 months (95% CI, 3.7-5.1).

In the subset of patients who received a prior PARP inhibitor (n = 50), the agent elicited an ORR of 38.0% (95% CI, 24.7%-52.8%), with a median DOR of 5.7 months (95% CI, 3.5-8.1). In those who did not receive a prior PARP inhibitor (n = 51), the ORR was 27.5% (95% CI, 15.9%-41.7%), with a median DOR of 5.9 months (95% CI, 3.0–not reached).

The BICR-assessed ORR was 31.6% (95% CI, 22.4%-41.9%) among 95 patients, which included a CR rate of 5.3% and a PR rate of 26.3%.

In terms of safety, all-grade adverse effects (AEs) occurred in 86% of patients; these effects were grade 3 in 27% of patients and grade 4 in 1% of patients. Most AEs were low-grade, reversible ocular and gastrointestinal events. Serious grade 3 or higher treatment-related AEs (TRAEs) occurred in 8% of patients.

The most common grade 3 effects with mirvetuximab soravtansine included keratopathy (8%), blurred vision (6%), dry eye (2%), diarrhea (2%), fatigue (1%), asthenia (1%), decreased appetite (1%), and neutropenia (1%). One patient experienced grade 4 keratopathy.

TRAEs led to dose reductions in 19% of patients; 32% of patients experienced dose delays, and 7% required discontinuations.

Additional efficacy and safety data from the mirvetuximab soravtansine program will be presented at the 2022 ASCO Annual Meeting.

ImmunoGen continues to enroll patients to the confirmatory phase 3 MIRASOL trial (NCT04209855), which is intended to convert the potential accelerated approval to full approval. Top-line data from this study are expected to read out in early 2023.

References

1. ImmunoGen announces acceptance of biologics license application for mirvetuximab soravtansine in ovarian cancer by US Food and Drug Administration with priority review. News release. ImmunoGen, Inc. May 23, 2022. Accessed May 23, 2022. https://bit.ly/3MV4AMt
2. ImmunoGen announces positive top-line results from pivotal SORAYA trial of mirvetuximab soravtansine in ovarian cancer. News release. ImmunoGen Inc. November 30, 2021. Accessed May 23, 2022. https://bit.ly/3Mzg9sl
3. 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. Presented at: 2022 SGO Annual Meeting on Women’s’ Cancers; March 18-21, 2022; Phoenix, AZ. Abstract 242.