Genmab reports ‘encouraging anti-tumor activity’ for Rina-S in Phase 1/2 trial

Genmab (GMAB) announced new data from cohort B2 of the Phase 1/2 RAINFOL-01 trial evaluating rinatabart sesutecan, or Rina-S, an investigational folate receptor alpha-targeted, TOPO1-inhibitor antibody-drug conjugate. The study showed that with a median on-study follow-up of 7.7 months, treatment with Rina-S 100 mg/m2 every 3 weeks resulted in a 50.0 percent confirmed objective response rate, including two complete responses, in heavily pre-treated advanced endometrial cancer patients who experienced disease progression on or after treatment with platinum-based chemotherapy and an immune checkpoint inhibitor. The median duration of response was not reached. These data are from the endometrial cancer monotherapy dose expansion B2 cohort of the multi-part RAINFOL-01 trial evaluating the safety and efficacy of Rina-S in solid tumors and were presented at the 2025 American Society of Clinical Oncology Annual Meeting in Chicago, Illinois. The B2 cohort of the Phase 1/2 RAINFOL-01 study is a dose expansion cohort evaluating the efficacy and safety of Rina-S in patients with advanced or recurrent endometrial cancer. In the study, 64 patients with heavily pretreated advanced or recurrent endometrial cancer whose disease had progressed on or after an anti-PD-(L)1 and platinum-based chemotherapy were enrolled and treated with Rina-S. Patients were administered either 100 mg/m2 or 120 mg/m2 of Rina-S. In the 100 mg/m2 cohort, the confirmed ORR was 50.0 percent, including two CRs. Anti-tumor activity was also observed in patients treated with Rina-S 120 mg/m2 Q3W, which resulted in 47.1 percent confirmed ORR. The mDoR was not reached after a median follow-up of 7.7 months in the 100 mg/m2 cohort and a median follow-up of 9.8 months in the 120 mg/m2 cohort. Median age was 67.0 years and 69.5 years in the 100 mg/m2 and 120 mg/m2 cohorts, respectively. Study participants were previously treated with a median of three lines of therapy. “Rina-S represents the kind of innovation that defines our focus at Genmab, which is to develop wholly owned, novel antibody-based medicines that have the potential to transform the treatment of cancer and address an unmet need, including for patients with advanced endometrial cancer,” said Judith Klimovsky, M.D., Executive Vice President and Chief Development Officer of Genmab. “The encouraging early signals in endometrial cancer underscore our deep commitment to making a meaningful impact for women with gynecologic cancers, where treatment advances have long lagged behind the need.”