Dr Van Gorp on the Long-Term Efficacy of Mirvetuximab Soravtansine in FRα+ Platinum-Resistant Ovarian Cancer

“We looked at OS, PFS, and all the other efficacy end points, and it was clear that the benefit that we saw during the primary analysis in 2023 [with mirvetuximab soravtansine over chemotherapy] is still maintained [after long-term follow-up].”

Toon Van Gorp, MD, PhD, a gynecologic oncologist at Universitair Ziekenhuis Leuven in Belgium, discusses data from the final analysis of the phase 3 MIRASOL trial (NCT04209855), which evaluated mirvetuximab soravtansine-gynx (Elahere) in patients with folate receptor alpha (FRα)–positive platinum-resistant ovarian cancer.

MIRASOL enrolled patients with platinum-resistant disease, FRα positivity, and high-grade serous histology, who had previously received 1 to 3 lines of therapy. Participants were randomized 1:1 to receive 6 mg/kg of the antibody-drug conjugate (ADC; n = 227) every 3 weeks or investigator’s choice of chemotherapy which could have been paclitaxel, pegylated liposomal doxorubicin, or topotecan (n = 226). Investigator-assessed progression-free survival (PFS) served as the trial’s primary end point.

The final analysis of the study had a median follow-up of 30.5 months, which Van Gorp noted to be very long follow-up for platinum-resistant disease. Data shared during the 2025 SGO Meeting on Women’s Cancers showed that median overall survival (OS) with mirvetuximab was 16.85 months (95% CI, 14.36-19.78) vs 13.34 months (95% CI, 11.37-15.15) with chemotherapy (HR, 0.68; 95% CI, 0.54-0.84; P = .0004). The median progression-free survival in the respective arms was 5.59 months (95% CI, 4.34-5.88) and 3.98 months (95% CI, 2.86-4.47; HR, 0.63; 95% CI, 0.51-0.79; P < .0001).

Mirvetuximab is the first treatment to demonstrate a clinically significant and meaningful OS benefit over chemotherapy in this population. Van Gorp underscored that the efficacy benefits observed in the primary analysis with mirvetuximab over chemotherapy were maintained with longer follow-up. Moreover, he noted that the survival curves were still separated 2 to 3 years later, suggestive that the effects of the ADC continue even after the next treatments that they may receive.