Updated MIRASOL Data Confirm Efficacy of Mirvetuximab Soravtansine for FRα+ Platinum-Resistant Ovarian Cancer

Mirvetuximab soravtansine-gynx (Elahere; AbbVie) continued to demonstrate superior clinical benefits in patients with folate receptor alpha-positive (FRα+), platinum-resistant ovarian cancer in the final analysis of the phase 3 MIRASOL trial (NCT04209855), as presented in a late-breaking session at the Society of Gynecologic Oncology (SGO) Annual Meeting on Women’s Cancer on Saturday.1

The final data analysis confirmed that mirvetuximab soravtansine-gynx (Elahere; AbbVie) significantly improves progression-free survival, overall survival, and objective response in patients with folate receptor alpha-positive (FRα+) platinum-resistant ovarian cancer. | Image Credit: Queenmoonlite Studio - stock.adobe.com

Primary Findings Led to FDA Approval

Mirvetuximab soravtansine received full FDA approval last March for the treatment of FRα+, platinum-resistant ovarian cancer following 1 to 3 prior lines of therapy based on the primary analysis of the phase 3 MIRASOL trial.2 It was previously granted accelerated approval in November 2022 based on results from the SOYAYA study (Study 0417).3

The randomized, phase 3 MIRASOL trial included 453 patients with FRα+, platinum-resistant ovarian cancer who received either mirvetuximab soravtansine (n = 227) or investigator’s choice chemotherapy (n = 226).2 The primary end point was progression-free survival, which was longer in the mirvetuximab soravtansine cohort (5.62 months [95% CI, 4.34-5.95]) than in the chemotherapy cohort (3.98 months [95% CI, 2.86-4.47]).

Additionally, patients in the mirvetuximab soravtansine cohort experienced significantly longer median overall survival at 16.46 months (95% CI, 14.46-24.57) vs 12.75 months (95% CI, 10.91-14.36) in the chemotherapy group (HR, 0.67; 95% CI, 0.50-0.89; P = .005).

Also, the objective response rate was significantly higher in the mirvetuximab soravtansine group (42.3%; 95% CI, 35.8-49.0) than in the chemotherapy group (15.9%; 95% CI, 11.4-21.4), translating to an OR of 3.81 (95% CI, 2.44-5.94; P < .001).

Of those who responded to mirvetuximab soravtansine in the primary analysis, 5.3% (n = 12) experienced a complete response and 37% (n = 84) had a partial response. Conversely, no patients in the chemotherapy cohort experienced a complete response, but 15.9% (n = 36) experienced a partial response.

Lastly, those taking mirvetuximab soravtansine experienced fewer adverse events of grade 3 or higher than the chemotherapy group. The most common adverse events among the mirvetuximab soravtansine group included blurred vision (n = 89; 40.8%), keratopathy (n = 70; 32.1%), abdominal pain (n = 66; 30.3%), and fatigue (n = 66; 30.3%).

Final Analysis Reinforces Clinical Benefits

As presented at the SGO Annual Meeting on Women's Cancer on Saturday, the final analysis of the phase 3 MIRASOL trial determined that patients treated with mirvetuximab soravtansine vs investigator’s choice chemotherapy continued to show significant improvements in progression-free and overall survival at 30.5 months median follow-up.1

More specifically, the mirvetuximab soravtansine group achieved a median progression-free survival of 5.59 months vs 3.98 months in the chemotherapy group, representing a 37% reduction in the risk of tumor progression or death (HR, 0.63; 95% CI, 0.51-0.79). Similarly, the mirvetuximab soravtansine group had a higher objective response rate (41.9%) than the chemotherapy group (15.9%).

Additionally, patients in the mirvetuximab soravtansine cohort experienced significantly longer median overall survival than those in the chemotherapy cohort (16.85 vs 13.34 months), representing a 32% reduction in the risk of death (HR, 0.68; 95% CI, 0.54-0.84).

Lastly, the safety data was consistent with that of the primary analysis. Therefore, the most common treatment-emergent adverse events among patients treated with mirvetuximab soravtansine were blurred vision, abdominal pain, keratopathy, and fatigue. Similarly, treatment with mirvetuximab soravtansine continued to be associated with lower rates of grade 3 or higher adverse events, treatment-emergent adverse events, serious adverse events, and treatment discontinuations due to adverse events.

In an interview with The American Journal of Managed Care®, investigator and presenter Toon Van Gorp, MD, PhD, of the University of Leuven, reflected on the final analysis, expressing confidence in mirvetuximab soravtansine as an effective treatment for this patient population.

“In my opinion, this means that mirvetuximab soravtansine should be considered as the standard of care for FRα+, platinum-resistant ovarian cancer,” he said. "It's also very important that we include FRα testing in our standard of care, that we do this from the start when the patient is first diagnosed with platinum-resistant ovarian cancer because I think it's really necessary that our patients receive this treatment.”

References

1. Elahere (mirvetuximab soravtansine-gynx) shows consistent survival benefit in long-term analysis for certain ovarian cancer patients. News release. AbbVie; March 15, 2025. Accessed March 17, 2025. https://news.abbvie.com/2025-03-15-ELAHERE-R-mirvetuximab-soravtansine-gynx-Shows-Consistent-Survival-Benefit-in-Long-Term-Analysis-for-Certain-Ovarian-Cancer-Patients
2. McNulty R. Mirvetuximab soravtansine-gynx granted full FDA approval for FRα+ platinum-resistant ovarian cancer. AJMC®. March 22, 2024. Accessed March 17, 2025. https://www.ajmc.com/view/mirvetuximab-soravtansine-gynx-granted-full-fda-approval-for-fr-platinum-resistant-ovarian-cancer
3. Joszt L. FDA approves mirvetuximab soravtansine-gynx for platinum-resistant ovarian cancer. AJMC. November 15, 2022. Accessed March 17, 2025. https://www.ajmc.com/view/fda-approves-mirvetuximab-soravtansine-gynx-for-platinum-resistant-ovarian-cancer