Rina-S Elicited Responses With/Without FRα Expression in Ovarian Cancer

Elizabeth Lee, MD, presented results from dose expansion cohort B1 of the phase 1/2 RAINFOL-01 trial (NCT05579366) at the 2025 Society of Gynecologic Oncology Annual Meeting on Women’s Cancer (SGO) that found rinatabart sesutecan (Rina-S) elicited “encouraging” antitumor activity in patients with ovarian cancer who were heavily pretreated.

Specifically, results found that Rina-S generated responses regardless of folate-receptor (FR)α expression levels. Pertaining to this, Lee, a medical oncologist in the gynecologic oncology program at Dana-Farber Cancer Institute and the gynecologic oncology program’s liaison to the Center for Cancer Therapeutics Innovation, told CancerNetwork® that FRα expression levels may correlate with whether certain patient subgroups have greater benefits with Rina-S than others.

The presentation did show that FRα was able to generate responses in the overall patient population, though there were greater responses in the group of patients that received the 120 mg/m² dose compared with the 100 mg/m² dose.

According to Lee, even though they need more data, there is a role for Rina-S, or another antibody-drug conjugate (ADC), to target epitopes on the cancer cell surface.

Transcript:

One of the factors that tie into [if there are any patient subgroups who have more benefit with Rina-S] is whether there’s a correlation—or not—with FRα expression level. The patients who were enrolled in the RAINFOL-01 study in cohort B1 of the dose expansion [phase] were allowed to enroll regardless of FRα expression level, so FRα expression level was only tested retrospectively. There are some preliminary data that we went through in our Focused Forum oral presentation [at SGO], but it does seem like there were responses with Rina-S 120 mg/m² [with] cutoffs both [higher] as well as below the 75% positive staining 2-plus threshold that we think about as being tied to the use of mirvituximab soravtansine-gynx [Elahere]. I would say that we’re still waiting for more numbers, more testing, and more biomarker correlation, but that there is, potentially, a role for Rina-S or other novel ADCs targeting different epitopes on the cancer cell surface. That could be very potent, even now, to very low levels of expression.

Reference

Lee EK, Yeku O, Winer I, et al. Rinatabart sesutecan (Rina-S®) for patients with advanced ovarian cancer: results from dose expansion cohort B1 of a phase 1/2 study. Presented at the 2025 Society of Gynecologic Oncology Annual Meeting on Women’s Cancer (SGO); March 14-17, 2025; Seattle, WA. Abstract 809034.