FDA Approval Sought for Mirvetuximab Soravtansine in FRα-High Platinum-Resistant Ovarian Cancer

A biologics license application (BLA) had been submitted to the FDA for mirvetuximab soravtansine monotherapy as a potential treatment option for patients with folate receptor alpha (FRα)-high platinum-resistant ovarian cancer who have been previously treated with 1 to 3 prior systemic treatments, according to an announcement by ImmunoGen, Inc.¹

Data from the phase 3 SORAYA clinical trial (NCT04296890) support the BLA for single-agent mirvetuximab soravtansine, an antibody-drug conjugate. Topline data from the study recently showed that the agent achieved meaningful anti-tumor activity with consistent safety and favorable tolerability, meeting the study’s primary end point.²

"The BLA submission for mirvetuximab soravtansine is a key inflection point on our journey to delivering a safe and effective treatment option to patients with platinum-resistant ovarian cancer and moves us one step closer to transforming ImmunoGen into a fully-integrated oncology company," said Mark Enyedy, president and chief executive officer, ImmunoGen, in a press release. "Platinum-resistant ovarian cancer is an area with high unmet need, and we look forward to working with [the] FDA to secure mirvetuximab soravtansine’s first approval and bringing this novel therapy to patients as quickly as possible."

SORAYA is a phase 3, single-arm study has thus far enrolled 106 of 110 patients with platinum-resistant high-grade serous epithelial ovarian cancer, primary peritoneal, or fallopian tube cancer, whose tumors express a high-level of FRα. Patients in the study are being treated with mirvetuximab soravtansine monotherapy at 6 mg/kg adjusted by ideal body weight administered on day 1 of every 3-week cycle and assessed for the primary end point of objective response rate (ORR), as well as for secondary end points including duration of response (DOR), adverse events, progression-free survival (PFS), overall survival, and CA-125 response.³

The median number of prior lines of therapy was 3 in the 106 patients enrolled. Fifty-one percent of patients had 3 prior lines of therapy and 48% had 1 to 2 prior lines of therapy. All patients received prior bevacizumab (Avastin), and 48% of patients received a prior PARP inhibitor.²

As of the data cutoff date of November 16, 2021, mirvetuximab soravtansine demonstrated an ORR of 32.4% (95% CI, 23.6%-42.2%) in the overall efficacy patient population (n = 105). Of the 34 patients who responded to the antibody drug conjugate, 5 patients achieved a complete response (CR), and 29 patients experienced a partial response (PR). Additionally, 45.7% of patients have stable disease (SD), and 19.0% experienced disease progression. The median DOR was 6.9 months (95% CI, 5.6-8.1) with the agent, and the median PFS with mirvetuximab soravtansine was 4.3 months (95% CI, 3.7-5.1).

In the group of patients who had previously received 1 to 2 lines of treatment, mirvetuximab soravtansine achieved an ORR of 35.3% (95% CI, 22.4%-49.9%), with a 5.9-month median DOR (95% CI, 4.2-8.1). Among patients who received 3 prior lines of treatment, mirvetuximab soravtansine induced an ORR of 30.2% (95% CI, 18.3%-44.3%), with a median DOR of 7.0 months (n = 16; 95% CI, 3.5-not reached [NR]).

In subjects who previously received a PARP inhibitor, the ORR shown with mirvetuximab soravtansine was 38.0% (95% CI, 24.7%-52.8%), and the median DOR was 5.7 months (n = 19; 95% CI, 3.5-8.1). Those who were not previously exposed to a PARP inhibitor had an ORR of 27.5% (95% CI, 15.9%-41.7%) with the agent, and the median DOR was 5.9 months (n = 14; 95% CI, 3.0-NR).

Finally, the ORR as assessed by the blind independent review (BICR) committee was 31.6% (95% CI, 22.4%-41.9%) among 95 patients, which included a CR rate of 5.3% as well as a PR rate of 26.3%. A total of 55.8% of patients achieved SD, and 8.4% experienced disease progression. The BICR-assessed median DOR was 11.7 months (95% CI, 5.0-NR), and the BICR-assessed median PFS was 5.5 months (95% CI, 3.8-6.9).

Overall, mirvetuximab was well-tolerated and consistent with the known safety profile. Treatment-related adverse events (TRAEs) resulted in dose reductions in 19% of patients, dose delays in 32%, and discontinuations in 7%. The most common TRAEs observed were low-grade and generally reversible, including blurred vision, keratopathy, and nausea.

_REFERENCE:

_{1. Immunogen submits biologics license application to the US Food and Drug Administration for mirvetuximab soravtansine in ovarian cancer. News release. ImmunoGen. March 29, 2022. Accessed March 29, 2022.}

_{2. ImmunoGen Presents Full Results from Positive Pivotal SORAYA Trial of Mirvetuximab Soravtansine in Ovarian Cancer at SGO Annual Meeting. News Release. ImmunoGen, Inc. March 19, 2022. Accessed March 29, 2022.}

_{3. Study of mirvetuximab soravtansine in platinum-resistant, advanced high-grade epithelial ovarian, primary peritoneal, or fallopian tube cancers with high folate receptor-alpha expression (SORAYA). Clinicaltrials.gov. Updated March 29, 2022. Accessed March 29, 2022. https://bit.ly/3LpemVL}