Genmab: Rina-S 120 mg/m2 led to ORR of 55.6% in Phase 2 RAINFOL trial

Genmab (GMAB) announced updated data from cohort B1 of the Phase 1/2 RAINFOL-01 study of rinatabart sesutecan, an investigational folate receptor-alpha-targeted, TOPO1 antibody-drug conjugate that showed Rina-S 120 mg/m2 every 3 weeks resulted in a confirmed objective response rate of 55.6% in heavily pre-treated ovarian cancer patients regardless of FRalpha expression levels. With a median on-study follow-up of 48 weeks, 1 out of 10 patients experienced disease progression and the median duration of response was not reached. The data are from the dose expansion cohort of the multi-part study evaluating the safety and efficacy of Rina-S as a single agent in solid tumors that are known to express FRalpha and were presented at the 2025 Society of Gynecologic Oncology Annual Meeting on Women’s Cancer in Seattle, Washington. “The antitumor activity observed in the dose expansion cohort continues to demonstrate the potential for a much-needed treatment option for patients with PROC, who have historically had poor prognosis. I am hopeful that further exploration of Rina-S will lead to advancements in the treatment landscape.” said Elizabeth Lee, M.D., a medical oncologist in the gynecologic oncology program at Dana-Farber. The B1 cohort is a dose expansion study in patients with histologically or cytologically confirmed advanced OC. Rina-S 120 mg/m2 Q3W at a median on-study follow-up of 48 weeks showed encouraging antitumor activity; the confirmed ORR was 55.6%, the disease control rate was 88.9%, and the median duration of response was not reached. In the 18 patients evaluable for response treated with 120 mg/m2 Q3W, complete responses were observed in 4 patients and 8 patients experienced confirmed partial responses (44.4%). Most responses with Rina-S 120 mg/m2 were observed early (at week 6). Only one patient in the 120 mg/m2 treatment arm was not evaluable. In the Rina-S 100 mg/m2 Q3W treatment arm, at a median on study follow-up of 46 weeks, the confirmed ORR was 22.7%, the DCR was 86.4%, and the mDOR was not reached. Partial responses were observed in 4 patients (18.2%) and 1 patient (4.5%) experienced a complete response. Rina-S 120 mg/m2 has been selected for further evaluation in the RAINFOL-01 and Phase 3 RAINFOL-02 trials for patients with platinum resistant ovarian cancer. In this Phase 1/2 study, common treatment-emergent adverse events included anemia, nausea, neutropenia, leukopenia, fatigue, thrombocytopenia, vomiting, diarrhea, alopecia, and hypokalemia. Dose reductions and treatment discontinuations were infrequent and no new safety signals were observed.