Mirvetuximab Soravtansine Shows Survival Benefit in Ovarian Cancer Subtype

Treatment with mirvetuximab soravtansine-gynx (Elahere) yielded improved outcomes compared with chemotherapy in patients with folate receptor α (FRα)–positive platinum-resistant ovarian cancer who have received prior therapy, according to a press release on topline data from the phase 3 MIRASOL (GOG 3045/ENGOT OV-55) trial (NCT04209855).¹

The FDA previously granted accelerated approval to mirvetuximab soravtansine in FRα-positive platinum-resistant ovarian cancer in November 2022.

The median overall survival (OS) was 16.46 months with mirvetuximab vs 12.75 months with chemotherapy of investigator’s choice (Hazard ratio [HR], 0.67; P = .0046). Additionally, the median progression-free survival (PFS) was 5.62 months vs 3.98 months in each respective arm (HR, 0.65; P <.0001).

The investigator-assessed objective response rate (ORR) was 42.3% with 12 patients achieving complete responses (CRs) with mirvetuximab vs 15.9% with no CRs with investigator’s choice chemotherapy. The PFS and ORR by blinded independent central review were consistent with the investigator assessments.

Based on data from the MIRASOL trial, investigators will submit a supplemental biologics license application to the FDA seeking conversion to a regular approval for mirvetuximab in FRα-positive platinum-resistant ovarian cancer following the agency’s decision to grant accelerated approval to the agent in November 2022.² Investigators also plan to submit a marketing authorization application for mirvetuximab’s approval in Europe.

“We believe these data will provide the foundation for pursuing a marketing authorization in Europe and elsewhere, and seeking full approval in the U.S., support our goal of delivering [mirvetuximab] to FRα-positive patients worldwide, and reinforce our conviction in our clinical development program to move this therapy into broader populations, including platinum-sensitive disease,” Mark Enyedy, president and chief executive officer of ImmunoGen, said in the press release.

Investigators of the randomized, open-label phase 3 MIRASOL trial evaluated mirvetuximab compared with chemotherapy in the treatment of patients with platinum-resistant FRα-positive ovarian cancer. In the experimental arm, patients received 6 mg/kg adjusted ideal body weight of mirvetuximab every 3 weeks. In the comparator arm, patients received either 80 mg/m² of paclitaxel once per week, 40 mg/m² of pegylated liposomal doxorubicin every 4 weeks, or 4 mg/m² of topotecan on days 1, 8, and 15 every 4 weeks or 1.25 mg/m² on days 1 to 5 every 3 weeks.

The primary end point was PFS by investigator assessment. Secondary end points included ORR, OS, duration of response, and safety and tolerability.

Patients 18 years and older who had a confirmed diagnosis of high-grade serous epithelial ovarian cancer, primary peritoneal cancer, or fallopian tube cancer with platinum-resistant disease were eligible for enrollment on the trial. Additional inclusion criteria included having tumors positive for FRα expression, progressive disease on or after the most recent line of therapy, and at least 1 measurable lesion per RECIST v1.1 criteria.

Investigators of the MIRASOL trial enrolled 453 patients. Overall, 14% of patients received 1 prior line of therapy, 39% received 2 prior lines, and 47% received 3 prior lines. Additionally, 62% of patients previously received treatment with bevacizumab (Avastin), and 55% received prior treatment with a PARP inhibitor.

There were no new safety signals identified in the MIRASOL trial. Grade 3 or higher treatment-emergent adverse effects (TEAEs) occurred in 42% of patients in the mirvetuximab arm vs 54% of those in the chemotherapy arm. Additionally, serious AEs occurred in 24% vs 33% of patients in each respective arm. TEAEs leading to treatment discontinuation occurred in 9% vs 16% of patients in each respective arm.

References

1. ELAHERE® demonstrates overall survival benefit in the phase 3 MIRASOL trial in patients with FRα-positive platinum-resistant ovarian cancer. News release. ImmunoGen. May 3, 2023. Accessed May 3, 2023. bit.ly/42pdZ6h
2. ImmunoGen announces FDA accelerated approval of ELAHERE™ (mirvetuximab soravtansine-gynx) for the treatment of platinum-resistant ovarian cancer. News release. ImmunoGen. November 14, 2022. Accessed May 3, 2023. https://bwnews.pr/3AayMyH