Dr Lee on the Future Development of Rina-S in FRα+ Platinum-Resistant Ovarian Cancer

“With these very encouraging results [from RAINFOL-01] we are hopeful to continue to advance the treatment landscape for patients with platinum-resistant ovarian cancer as a whole.”

Elizabeth Lee, MD, a medical oncologist at Dana-Farber Cancer Institute and an instructor in medicine at Harvard Medical School, discussed next steps with the novel folate receptor alpha (FRα)–directed antibody-drug conjugate rinatabart sesutecan (Rina-S; PRO1184) for the treatment of patients with FRα-expressing high-grade serous or endometrioid platinum-resistant ovarian cancer.

Findings from cohort B1 of the phase 1/2 RAINFOL-01 trial (NCT05579366) presented during the 2025 SGO Annual Meeting on Women’s Cancer showed that, at a median follow-up of 46 months, patients who received Rina-S at 100 mg/m2 every 3 weeks (n = 22) achieved a confirmed overall response rate (ORR) of 22.7% (95% CI, 7.8%-45.4%), including 1 patient with a complete response, and a disease control rate of 86.4% (95% CI, 65.1%-97.1%). Notably, the median duration of response was not reached (NR; 95% CI, 16.3-NR).

In terms of safety, common treatment-emergent adverse effects included anemia, nausea, neutropenia, leukopenia, fatigue, thrombocytopenia, vomiting, diarrhea, alopecia, and hypokalemia. No new safety signals were reported, and dose reductions and therapy discontinuations were not common.

Investigators are hopeful that data from RAINFOL-01 will continue to advance the treatment paradigm in platinum-resistant ovarian cancer, Lee said. She noted that the dose-expansion data presented during the 2025 SGO Annual Meeting were in a limited subset of patients. Part C of RAINFOL-01, which will enroll approximately 100 patients with advanced ovarian cancer, will provide additional data, she added. However, based on the encouraging findings from RAINFOL-01, investigators have initiated the phase randomized phase 3 RAINFOL-02 trial (NCT06619236) comparing Rina-S with investigator’s choice of chemotherapy, she concluded.

RAINFOL-02 is an open-label trial that is enrolling patients irrespective of FRα levels with platinum-resistant ovarian cancer. Patients are required to have received 1 to 4 prior lines of therapy. The primary end point is progression-free survival (PFS). Secondary end points include overall survival, ORR, DOR, time to second PFS, quality of life measures, and safety.