Merck’s KEYTRUDA plus chemotherapy gains EU approval for PD-L1–positive platinum-resistant ovarian cancer, supported by Phase 3 KEYNOTE-B96 data showing improved PFS and OS.
Written By: A. Musharaf Mohammad, BPharm
Reviewed By: Pharmacally Editorial Team
Merck & Co. has received European Union approval for its anti–PD-1 therapy KEYTRUDA (pembrolizumab) in combination with paclitaxel, with or without bevacizumab, for the treatment of adult patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal carcinoma whose tumors express PD-L1 (combined positive score ≥1) and who have received one or two prior systemic regimens.
The approval establishes the regimen as the first PD-1 inhibitor–based treatment option for this patient population in the EU. It applies across all 27 EU member states, as well as Iceland, Liechtenstein, and Norway, with country-level availability dependent on national reimbursement processes.
Clinical Context and Unmet Need
Patients with ovarian cancer who develop resistance to platinum-based chemotherapy have limited treatment options and poor prognosis. Dr. Nicoletta Colombo, Director of the Gynecologic Oncology Program at the European Institute of Oncology, highlighted that disease progression after standard therapy represents a significant unmet need, and described the pembrolizumab-based regimen as an important addition for eligible patients with PD-L1–positive disease.
Phase 3 KEYNOTE-B96 Trial Results
The approval is supported by data from the Phase 3 KEYNOTE-B96 (ENGOT-ov65) trial (NCT05116189), a randomized, double-blind, placebo-controlled study evaluating pembrolizumab in combination with chemotherapy. In patients with PD-L1–positive platinum-resistant ovarian cancer, the regimen demonstrated a 28% reduction in the risk of disease progression or death (HR 0.72; p=0.0014), with a median progression-free survival of 8.3 months compared with 7.2 months in the control group. The treatment also reduced the risk of death by 24% (HR 0.76; p=0.0053), with median overall survival improving to 18.2 months versus 14.0 months with chemotherapy alone. These findings indicate statistically significant and clinically meaningful improvements in both primary and key secondary endpoints.
KEYNOTE-B96 enrolled 643 patients with recurrent ovarian cancer who had received one or two prior lines of therapy, including platinum-based chemotherapy. Patients were randomized to receive pembrolizumab plus paclitaxel, with or without bevacizumab, or placebo plus chemotherapy. Approximately 72% of enrolled patients had PD-L1–positive tumors.
Regulatory Background
The EU decision follows a positive recommendation from the European Medicines Agency’s Committee for Medicinal Products for Human Use in February 2026. A similar indication was approved earlier by the U.S. Food and Drug Administration in February 2026 for patients with PD-L1–positive platinum-resistant disease.
Dr. Gursel Aktan, Vice President of Global Clinical Development at Merck Research Laboratories, stated that the approval expands access to a new immunotherapy-based option for patients in Europe and reflects ongoing efforts to broaden treatment choices in women’s cancers.
Disease Burden
Ovarian cancer remains a major global health challenge, with more than 324,000 new cases and nearly 207,000 deaths reported worldwide in 2022. More than 80% of patients experience disease progression after first-line platinum-based therapy, and approximately one-quarter develop platinum-resistant disease within six months.
Mechanism of Action
Pembrolizumab is a monoclonal antibody targeting the PD-1 receptor. By blocking interaction with PD-L1 and PD-L2, it enhances T-cell–mediated immune responses against tumor cells.
This approval adds to Merck’s expanding immuno-oncology portfolio and supports continued development of combination strategies in gynecologic cancers.
Reference
Pembrolizumab/Placebo Plus Paclitaxel with or Without Bevacizumab for Platinum-resistant Recurrent Ovarian Cancer (MK-3475-B96/KEYNOTE-B96/ENGOT-ov65), ClinicalTrials.gov ID NCT05116189, https://clinicaltrials.gov/study/NCT05116189
About the Writer
Mohamed Musharaf A is a Pharmacy graduate from Ariyur, Puducherry, with a strong interest in data analysis and its application in healthcare. He is particularly interested in using data-driven insights to support pharmacovigilance and medical writing, with a focus on understanding complex datasets and translating them into meaningful, actionable solutions. Known for his dedication to learning and attention to detail, he continuously works to strengthen his analytical and domain knowledge.