Genmab's Rina-S hits 46% response rate in PROC trial

Genmab has presented Phase 2 results showing its antibody-drug conjugate (ADC) rinatabart sesutecan (Rina-S) achieved a confirmed objective response rate of 45.9% (95% CI: 36.3–55.7) in 109 patients with platinum-resistant ovarian cancer (PROC), including five complete responses. The median duration of response was 12.1 months, with 51% of responders remaining in response at one year. Data were presented in a late-breaking oral session at the International Gynecologic Cancer Society Congress 2026 in Montreal.

The study also reported a median progression-free survival of 9.5 months (95% CI: 7.6–11.3), described by Genmab as the first PFS data disclosed for the programme. More than half the patients (53%) had received three or four prior lines of therapy; all had received prior bevacizumab and taxane, 49.5% had received a prior PARP inhibitor, and 33% had previously received mirvetuximab soravtansine.

Clinical significance

A notable feature of the dataset is that antitumour activity was observed irrespective of folate receptor alpha (FRα) expression level, including in patients with low expression and non-expressors. This distinguishes the profile of Rina-S from mirvetuximab soravtansine, the only approved FRα-targeting ADC in PROC, which carries a biomarker-selected label requiring high FRα expression. If the expression-agnostic signal is confirmed in Phase 3, it would meaningfully broaden the eligible patient population.

Elizabeth K. Lee, medical oncologist at Dana-Farber Cancer Institute and a study investigator, said the "antitumor activity and durability observed with Rina-S in this heavily pretreated population are encouraging and suggest the potential to meaningfully impact outcomes for patients facing a particularly challenging stage of disease."

The safety profile was largely consistent with other TOPO1-inhibitor ADCs. The most common treatment-emergent adverse events were gastrointestinal, including nausea (67.9%), fatigue (57.8%), and haematologic events such as anaemia and neutropenia (both 57.8%). Serious adverse events were reported in approximately one-third of participants. Treatment discontinuation due to adverse events was low at 5.5%, and no signals for ocular toxicity, peripheral neuropathy, interstitial lung disease, or stomatitis were observed.

Competitive landscape and Phase 3 path

PROC is a crowded and increasingly competitive space. Beyond mirvetuximab, a number of next-generation ADCs and TOPO1-payload compounds are in development across the sector, and the expression-agnostic activity of Rina-S will be closely watched by both investors and clinicians. The ADC field more broadly has seen rapid expansion since the approvals of trastuzumab deruxtecan and sacituzumab govitecan, and the TOPO1-inhibitor payload class that Rina-S employs has become a preferred warhead for several programmes in solid tumours.

Genmab is advancing four Phase 3 trials under its RAINFOL programme: RAINFOL-02 in PROC, RAINFOL-03 in recurrent endometrial cancer, RAINFOL-04 in platinum-sensitive ovarian cancer maintenance, and RAINFOL-07 in second-line platinum-sensitive ovarian cancer. Phase 2 trials in non-small cell lung cancer and advanced gastrointestinal cancers are also under way. The breadth of the programme reflects Genmab's ambition to establish Rina-S as a platform asset across gynaecological and other solid tumours, though regulatory approval in any indication remains contingent on Phase 3 outcomes.