Clinical Summary:

• Design/Context: The phase 1/2 RAINFOL-01 study evaluated rinatabart sesutecan plus bevacizumab in recurrent ovarian cancer.
• Key Outcomes:The regimen was generally well tolerated, with predominantly hematologic and gastrointestinal toxicities and no significant neuropathy, ocular toxicity, or interstitial lung disease observed.
• Clinical Relevance: These findings support continued development of this folate receptor alpha-targeted antibody drug conjugate combination in ovarian cancer, including ongoing studies in the maintenance setting.

Cara Mathews, MD, Brown University, Providence, Rhode Island, discusses results from the cohort D2 of the phase 1/2 RAINFOL-01 study assessing rinatabart sesutecan plus bevacizumab in patients with recurrent ovarian cancer. 

Results demonstrated that this combination demonstrates manageable safety with limited nonhematologic toxicity, supporting ongoing evaluation in platinum-sensitive maintenance settings.

Dr Mathews presented these results at the 2026 Society of Gynecologic Oncology (SGO) Annual Meeting in San Juan, Puerto Rico. 

Transcript: 

I’m Cara Mathews and I’m an associate professor of obstetrics and gynecology as gynecologic oncologist in the Legorreta Cancer Center at Brown University.

This study was a phase 1b expansion cohort in patients with recurrent ovarian cancer who were treated with a combination of rinatabart sesutecan (Rina-S), a novel antibody-drug conjugate, and bevacizumab.

Rina-S had been previously studied in patients with recurrent ovarian cancer to identify a potential dose level, and a dose of 120 mg/m² had been identified. This study was really looking at that dose in combination with bevacizumab because both drugs have different toxicities and mechanisms of action. Rina-S itself is a folate receptor alpha–targeted antibody-drug conjugate with an exatecan payload and a drug-to-antibody ratio of 8. In previous studies, its toxicities were primarily hematologic, along with some fairly well-managed gastrointestinal toxicity. Importantly, there was no ocular toxicity, no interstitial lung disease, and no neuropathy – this was unique compared to other folate receptor–targets currently available.

This study primarily looked at toxicity as the primary outcome. There were 40 patients with recurrent ovarian cancer enrolled and they represented a very heterogeneous population including platinum-sensitive, platinum-resistant, and platinum-refractory disease. Patients could also have multiple epithelial histologic subtypes of ovarian cancer. All folate receptor alpha expression levels were accepted, this was not part of the eligibility criteria, and was instead evaluated after enrollment. Patients were treated with the combination of Rina-S and bevacizumab every 21 days and evaluated for toxicity. 

Overall, the combination was very well tolerated with primarily manageable GI and hematologic toxicities observed. About 50% of patients experienced a grade 3/4 toxicity, and those were almost exclusively hematologic including anemia, thrombocytopenia, and neutropenia. About 80% of patients experienced grade 1/2 gastrointestinal toxicities, primarily nausea.

After approximately 14 patients had enrolled, there was a protocol amendment mandating growth factor support to prevent the severe neutropenia that had been observed. Subsequently, the majority of patients received G-CSF support. Overall, the drug was well tolerated. Nearly 85% of patients received more than 6 cycles and it was rare for patients to discontinue treatment due to toxicity. Importantly, there was again no neuropathy, interstitial lung disease, or ocular toxicity observed. 

These findings were exciting in terms of the tolerability of the combination and really support moving this regimen forward into an efficacy study in a more homogeneous patient population. The study is currently ongoing, and this combination will be studied in the maintenance setting for platinum-sensitive ovarian cancer following platinum-based doublet therapy.

Source: 

Mathews C, Pepin JT, Cloven N, et al. Rinatabart sesutecan (Rina-S) plus bevacizumab (BEV) for patients (pts) with recurrent ovarian cancer (OC): First disclosure from cohort D2 of the phase 1/2 RAINFOL-01 study. Presented at SGO Annual Meeting on Women’s Cancer. April 10 - 13, 2026; San Juan, Puerto Rico.