Novel Antibody-Drug Conjugate Demonstrates Durable Responses in Patients With Platinum-Resistant Ovarian Cancer

An investigational antibody-drug conjugate demonstrated clinically meaningful and durable responses in patients with platinum-resistant ovarian cancer, including patients whose tumors had low or no expression of folate receptor alpha (FRalpha), according to findings from the Phase 1/2 RAINFOL-01 clinical trial.

By
October 8, 2026
4 min

Dana-Farber

Overview

In the Phase 1/2 RAINFOL-01 trial, the investigational FRα-targeted antibody-drug conjugate rinatabart sesutecan (Rina-S) produced a confirmed objective response in 45.9% of 109 treated patients with platinum-resistant ovarian, primary peritoneal, or fallopian tube cancer. Median duration of response was 12.1 months and median progression-free survival was 9.5 months; antitumor activity was reported across FRα expression levels, including low or absent expression.

Background

Platinum-resistant ovarian cancer is described by study investigator Elizabeth K. Lee as difficult to treat, with limited options as disease progresses through successive lines of therapy. RAINFOL-01 enrolled patients with platinum-resistant high-grade serous ovarian, primary peritoneal, or fallopian tube cancer after one to three prior lines of therapy, with up to four permitted for patients whose most recent treatment was mirvetuximab. All participants had previously received bevacizumab and a taxane, and more than half had received three or four prior lines. Rina-S is an investigational antibody-drug conjugate comprising an FRα-directed monoclonal antibody, a cleavable linker, and the topoisomerase I inhibitor exatecan.

Data Highlights

Measure	Finding
Patients treated	109
Confirmed objective response rate	45.9%, including 5 complete responses
Median duration of response	12.1 months
Responders remaining in response at 1 year	51%
Median progression-free survival	9.5 months
Median duration of response among patients previously treated with mirvetuximab	13.1 months
Treatment-related adverse events leading to discontinuation	1.8%

Key Findings

RAINFOL-01 was an open-label, multicenter Phase 1/2 study evaluating Rina-S safety and efficacy at different doses in patients with selected solid tumors; the reported cohort had platinum-resistant ovarian, primary peritoneal, or fallopian tube cancer.
Among 109 treated patients, 45.9% had a confirmed objective response, including five complete responses.
Median duration of response was 12.1 months; 51% of responders remained in response at one year, and median progression-free survival was 9.5 months.
Antitumor activity was reported regardless of FRα expression, including in patients with low FRα expression or tumors reported not to express FRα.
Responses were reported regardless of prior mirvetuximab treatment; among patients previously treated with mirvetuximab, median duration of response was 13.1 months.
Commonly reported adverse effects included fatigue and gastrointestinal symptoms, as well as anemia, neutropenia, and thrombocytopenia. Treatment-related adverse events led to discontinuation in 1.8% of patients; the study reported no safety signals for ocular toxicity, peripheral neuropathy, interstitial lung disease, or stomatitis.

Clinical Implications

Lee stated that further studies are needed to determine Rina-S's role in ovarian cancer treatment. The source reports that the randomized Phase 3 RAINFOL-02 trial is enrolling patients; Rina-S remains investigational.

Conclusion

RAINFOL-01 reported objective responses and durable disease control with Rina-S in a heavily pretreated platinum-resistant population, with activity described across FRα expression levels. The treatment's role remains under investigation in further clinical trials.