Merck’s KEYNOTE-B96 Trial Achieves Overall Survival Milestone In Platinum-Resistant Ovarian Cancer

Merck , known as MSD outside the U.S. and Canada, announced that its Phase 3 KEYNOTE-B96 (ENGOT-ov65) trial met its secondary endpoint of overall survival (OS) for patients with platinum-resistant recurrent ovarian cancer. The study evaluated KEYTRUDA® (pembrolizumab), Merck’s anti-PD-1 therapy, in combination with chemotherapy (paclitaxel) with or without bevacizumab. Previously, the trial achieved its primary endpoint of progression-free survival (PFS) in both PD-L1–positive patients and the overall population, as well as OS in PD-L1–positive patients. Comprehensive results will be shared at the European Society for Medical Oncology (ESMO) Congress 2025.

At the final analysis, the KEYTRUDA combination showed a statistically significant and clinically meaningful OS improvement across all patient groups compared with placebo plus chemotherapy (with or without bevacizumab). The safety profile was consistent with prior studies, and no new safety concerns were identified. These results further strengthen the clinical evidence supporting KEYTRUDA’s role in treating difficult-to-treat cancers, even though it is not yet approved for ovarian cancer.

“The results from the KEYNOTE-B96 trial mark the first time ever that an immune checkpoint inhibitor-based regimen has demonstrated the potential to help all patients with platinum-resistant recurrent ovarian cancer,” said Dr Gursel Aktan, vice president, global clinical development, Merck Research Laboratories. “These women face a very poor prognosis with limited options for treatment, and this impactful news is a testament to our tireless commitment to exploring new options for patients with gynecologic cancers who face a critical unmet need.”

Merck also highlighted ongoing progress with LYNPARZA (olaparib), co-developed with AstraZeneca, which currently holds three FDA-approved indications for ovarian cancer maintenance therapy following platinum-based chemotherapy. Additionally, Merck and Daiichi Sankyo announced new data from the REJOICE-Ovarian01 trial investigating raludotatug deruxtecan (R-DXd) for platinum-resistant ovarian cancers. R-DXd recently received Breakthrough Therapy Designation from the U.S. FDA based on promising results and continues to advance as a potential new treatment option.