Genmab reports a 45.9% response rate, 12.1-month response duration and 9.5-month PFS with Rina-S in platinum-resistant ovarian cancer.
Written By: Neha Vishwakarma, PharmD
Reviewed By: Pharmacally Editorial Team
Genmab has reported results from Part C of the Phase 1/2 RAINFOL-01 trial evaluating rinatabart sesutecan (Rina-S, GEN1184), an investigational folate receptor alpha (FRα)-targeted topoisomerase I (TOPO1) inhibitor antibody-drug conjugate (ADC). The data were presented on October 3, 2026, in a Late-Breaking Oral Session at the International Gynecologic Cancer Society (IGCS) Congress 2026 in Montreal, Canada.
The Part C analysis evaluated Rina-S in heavily pretreated patients with platinum-resistant ovarian cancer (PROC) and provided the first progression-free survival data from the program.
Disease Background
Ovarian cancer is diagnosed in more than 320,000 people worldwide each year and is frequently diagnosed at an advanced stage because early symptoms can be subtle and nonspecific. Genmab reports that approximately 70% to 90% of patients with advanced-stage disease experience recurrence after initial treatment, while five-year survival generally ranges from 30% to 50%.
Once ovarian cancer becomes resistant to platinum-based treatment, therapeutic options become more limited and responses to subsequent therapies may be less durable. This makes sustained tumor control an important treatment goal in this population.
RAINFOL-01 Study Design
RAINFOL-01 (NCT05579366) is an open-label, multicenter Phase 1/2 study evaluating Rina-S at different doses every three weeks in patients with selected solid tumors across a range of FRα expression levels.
Part C evaluated Rina-S at 120 mg/m² every three weeks as monotherapy in 109 treated patients with platinum-resistant high-grade serous ovarian, primary peritoneal, or fallopian tube cancer.
Patients had received one to three prior lines of therapy, or up to four prior lines if mirvetuximab was their most recent treatment. Among the treated population:
- 53% had received three or four prior lines of therapy.
- All patients had previously received bevacizumab and a taxane.
- 49.5% had received a prior PARP inhibitor.
- 33% had previously received mirvetuximab soravtansine.
- Median follow-up exceeded one year.
Rina-S Shows 45.9% Confirmed Response Rate
At the 120 mg/m² dose administered every three weeks, Rina-S produced a confirmed objective response rate of 45.9% (95% CI, 36.3–55.7) among the 109 treated patients. Five patients achieved a complete response.
The median duration of response was 12.1 months (95% CI, 6.5–15.4), with 51% of responders remaining in response at one year.
The median progression-free survival was 9.5 months (95% CI, 7.6–11.3).
Antitumor activity was observed across different levels of FRα expression, including patients with low FRα expression and patients classified as non-expressors. Activity was also observed regardless of prior treatment with mirvetuximab soravtansine.
These findings are notable because the study population had received multiple prior therapies and included patients with platinum-resistant disease, a setting in which durable responses can be difficult to achieve.
Safety Profile of Rina-S
The safety profile was characterized primarily by fatigue, gastrointestinal events and hematologic toxicities.
Fatigue occurred in 57.8% of patients. Gastrointestinal adverse events were predominantly Grade 1–2 and included nausea (67.9%), vomiting (36.7%), constipation (26.6%), decreased appetite (23.9%) and abdominal pain (18.3%).
Hematologic adverse events included anemia (57.8%), neutropenia (57.8%), decreased platelet count (34.9%) and thrombocytopenia (34.9%).
Serious adverse events were reported in approximately one-third of participants, while 5.5% discontinued treatment because of treatment-emergent adverse events.
Genmab reported no safety signals for ocular toxicity, peripheral neuropathy, interstitial lung disease or stomatitis.
Rina-S Development Expands Beyond Ovarian Cancer
Rina-S is an ADC comprising a human monoclonal antibody targeting FRα, a hydrophilic protease-cleavable linker and exatecan as the TOPO1 inhibitor payload.
Genmab is advancing Rina-S through a broad clinical development program that includes four Phase 3 studies:
- RAINFOL-02 (NCT06619236): platinum-resistant ovarian cancer
- RAINFOL-03 (NCT07166094): recurrent or progressive endometrial cancer
- RAINFOL-04 (NCT07225270): maintenance treatment in platinum-sensitive ovarian cancer
- RAINFOL-07 (NCT07564141): second-line treatment of platinum-sensitive ovarian cancer
Phase 2 studies are also evaluating Rina-S in non-small cell lung cancer (RAINFOL-05, NCT07288177) and advanced gastrointestinal cancers (RAINFOL-09, NCT07539311).
Elizabeth K. Lee, M.D., a study investigator at Dana-Farber Cancer Institute, said the activity and durability observed in this heavily pretreated population were encouraging. Tahamtan Ahmadi, M.D., Ph.D., Genmab’s Chief Medical Officer, said the results, including the first progression-free survival data from the program, support continued development of Rina-S as the Phase 3 program advances.
Interpretation and Limitations
The RAINFOL-01 Part C results are from a single-arm, open-label study, meaning there was no randomized comparator against standard chemotherapy. The results therefore cannot establish comparative efficacy, and cross-trial comparisons with other FRα-directed therapies or treatments for platinum-resistant ovarian cancer should be avoided because of differences in patient populations and study designs.
The median duration of response was estimated with a relatively wide 95% confidence interval of 6.5 to 15.4 months, while five complete responses were reported. Hematologic toxicities were common, and serious adverse events occurred in approximately one-third of participants.
The observed activity across FRα expression levels is an important finding, but whether this apparent broader activity translates into a clinically meaningful advantage requires confirmation in larger, controlled studies, including the ongoing Phase 3 RAINFOL-02 trial.
Rina-S remains investigational, and its safety and efficacy have not been established.
Reference
Genmab Announces Rinatabart Sesutecan (Rina-S®) Phase 2 RAINFOL™-01 Results Demonstrated Durable and Clinically Meaningful Responses in Patients with Platinum-Resistant Ovarian Cancer, Genmab, 03 October 2026
Rinatabart Sesutecan (Rina-S, PRO1184, GEN1184) for Advanced Solid Tumors (GCT1184-01/ PRO1184-001) (RAINFOL-01), ClinicalTrials.gov ID NCT05579366
About the Writer
Neha Vishwakarma (Linkedin) is a Pharm.D professional with experience in clinical pharmacy, pharmacovigilance, and clinical research. She has hands-on experience in ADR assessment, ICSR processing, medication safety, and clinical data evaluation. Her research background in surgical site infections and antibiotic use supports her focus on evidence-based healthcare writing.