RAHWAY - Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced results from the final analysis of the pivotal Phase 3 KEYNOTE-B96 trial, also known as ENGOT-ov65, showing that KEYTRUDA (pembrolizumab), Merck's anti-PD-1 therapy, in combination with chemotherapy (paclitaxel) with or without bevacizumab significantly improved overall survival (OS), a key secondary endpoint, for patients with platinum-resistant recurrent ovarian cancer regardless of PD-L1 status versus paclitaxel with or without bevacizumab alone, the most active standard of care control arm for patients who are bevacizumab-eligible.
These data will be presented for the first time today during a Best Oral Session at the European Society of Gynaecological Oncology (ESGO) 2026 Congress (abstract #526).
As previously reported at the European Society for Medical Oncology (ESMO) Congress 2025, KEYTRUDA plus paclitaxel with or without bevacizumab met its primary endpoint of progression-free survival (PFS) in the all comers population of patients with platinum-resistant recurrent ovarian cancer, as well as in patients whose tumors express PD-L1 (Combined Positive Score [CPS] =1). The KEYTRUDA regimen also met its key secondary endpoint of OS in patients with platinum-resistant recurrent ovarian cancer whose tumors express PD-L1 (CPS =1).
At the final analysis, after a median follow-up of 32.7 months (range, 26.1-44.1), KEYTRUDA plus paclitaxel with or without bevacizumab demonstrated a statistically significant and clinically meaningful improvement in OS in all comers, reducing the risk of death by 18% (HR=0.82 [95% CI, 0.69-0.97]; p=0.0115) compared to paclitaxel with or without bevacizumab alone. For patients who received the KEYTRUDA regimen, median OS was 17.7 months versus 14.0 months for patients receiving the placebo regimen. The observed OS is among the longest reported in any clinical trial for platinum-resistant recurrent ovarian cancer, showing a clinically meaningful benefit of this regimen relative to the most active standard of care control arm, weekly paclitaxel with bevacizumab in bevacizumab-eligible patients.
'Patients with platinum-resistant ovarian cancer show reduced responses to traditional treatment regimens and may experience poor overall survival,' said Dr. Nicoletta Colombo, director of the Gynecologic Oncology Program at the European Institute of Oncology in Milan, Italy. 'These results build on prior data from the KEYNOTE-B96 trial and further define the clinical impact of this pembrolizumab-based regimen in appropriate patients with platinum-resistant recurrent ovarian cancer.'
Additionally, the European Medicines Agency's Committee for Medicinal Products for Human Use (CHMP) adopted a positive opinion recommending approval of KEYTRUDA in combination with paclitaxel with or without bevacizumab for the treatment of platinum-resistant epithelial ovarian, fallopian tube or primary peritoneal carcinoma in adults whose tumors express PD-L1 (CPS =1), and who have received one or two prior systemic treatment regimens.
In February, KEYTRUDA plus paclitaxel with or without bevacizumab was approved by the U.S. Food and Drug Administration (FDA) to treat adult patients with platinum-resistant epithelial ovarian, fallopian tube or primary peritoneal carcinoma whose tumors express PD-L1 (CPS =1) as determined by an FDA-authorized test, and who have received one or two prior systemic treatment regimens based on previous data from the KEYNOTE-B96 trial.
'Results from the final analysis of KEYNOTE-B96, including overall survival data in the all comers population, demonstrate the continued clinical benefit of KEYTRUDA plus paclitaxel with or without bevacizumab for certain patients with platinum-resistant recurrent ovarian cancer,' said Dr. Gursel Aktan, vice president, global clinical development, Merck Research Laboratories. 'Taken together, the recent FDA approval and CHMP positive opinion underscore our commitment to the ovarian cancer community and our ongoing focus on delivering therapies that can help patients with unmet needs across women's cancers.'
Study design and additional data from KEYNOTE-B96/ENGOT-ov65
KEYNOTE-B96, also known as ENGOT-ov65, is a multicenter, randomized, double-blind placebo-controlled Phase 3 trial (ClinicalTrials.gov, NCT05116189) sponsored by Merck and conducted in collaboration with the European Network for Gynecologic Oncology Trial (ENGOT) groups investigating KEYTRUDA, Merck's anti-PD-1 therapy, in combination with chemotherapy (paclitaxel) with or without bevacizumab compared to placebo plus paclitaxel with or without bevacizumab for the treatment of platinum-resistant recurrent ovarian cancer. The primary endpoint is PFS, as assessed by investigator according to Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1), and OS is a key secondary endpoint. The trial enrolled 643 patients with epithelial ovarian, fallopian tube or primary peritoneal carcinoma, regardless of PD-L1 tumor expression status, who received one or two prior lines of systemic therapy for ovarian carcinoma, including at least one line of platinum-based chemotherapy. Of the 643 enrolled patients, 72% of patients had tumors expressing PD-L1 (CPS =1). Patients were enrolled in KEYNOTE-B96 regardless of PD-L1 tumor expression status. Patients were randomized (1:1) to receive either KEYTRUDA plus paclitaxel with or without bevacizumab, or placebo plus paclitaxel with or without bevacizumab. KEYTRUDA (400 mg) or placebo were administered on Day 1 of each six-week treatment cycle and paclitaxel (80 mg/m2) was administered on Days 1, 8 and 15 of each three-week treatment cycle. The option to use bevacizumab was by investigator choice prior to randomization. Bevacizumab (10 mg/kg) was administered on Day 1 of a two-week treatment cycle.
At the final analysis, in the all comers population, KEYTRUDA plus paclitaxel with or without bevacizumab reduced the risk of disease progression or death by 27% (HR=0.73 [95% CI, 0.62-0.87]) compared to paclitaxel with or without bevacizumab alone. In patients with platinum-resistant recurrent ovarian cancer whose tumors express PD-L1 (CPS =1), the KEYTRUDA regimen reduced the risk of disease progression or death by 24% (HR=0.76 [95% CI, 0.62-0.93]) versus paclitaxel with or without bevacizumab alone. The KEYTRUDA regimen also continued to demonstrate a clinically meaningful improvement in OS, a key secondary endpoint of the study, in patients with platinum-resistant recurrent ovarian cancer whose tumors express PD-L1 (CPS =1), reducing the risk of death by 24% (HR=0.76 [95% CI, 0.62-0.93]) compared to paclitaxel with or without bevacizumab.
The safety profile of KEYTRUDA in this trial was consistent with that observed in previously reported studies; no new safety concerns were identified. Grade =3 treatment-related adverse events (TRAEs) occurred in 67.8% of patients receiving the KEYTRUDA regimen (n=320) versus 55.3% of patients receiving the placebo regimen (n=318). TRAEs led to death in 1.3% of patients receiving the KEYTRUDA regimen and 1.6% of patients receiving the placebo regimen.
Immune-mediated adverse events (AEs) and infusion reactions of any grade occurred in 39.4% of patients receiving the KEYTRUDA regimen and 18.9% of patients receiving the placebo regimen. The most common of these events (occurring in =10% of patients) was hypothyroidism (18.1%) in patients receiving the KEYTRUDA regimen. Immune-mediated AEs led to death in 0.6% of patients in the KEYTRUDA arm and in no patients in the placebo arm.
About platinum-resistant ovarian cancer
Ovarian cancer often begins in the fallopian tubes or the ovaries. As of 2022, it is the eighth most commonly diagnosed cancer and the eighth leading cause of cancer death among women worldwide. Globally, there were more than 324,000 patients diagnosed with ovarian cancer and almost 207,000 deaths from the disease in 2022. In many regions, its incidence has been increasing, with estimates projecting a 42% increase in new cases worldwide by 2040. Over 80% of patients diagnosed with ovarian cancer will experience disease progression following standard treatment with platinum-based chemotherapy regimens. Of these patients, approximately 25% will experience disease progression within six months of completing first-line platinum-based chemotherapy - defined as primary platinum-resistant ovarian cancer. Prognosis is particularly poor for these patients and approved treatment options are limited.
About Merck's research in women's cancers
Merck is advancing research aimed at expanding treatment options for certain breast and gynecologic (ovarian, cervical and endometrial) cancers, with a goal of improving outcomes for more patients affected by these diseases. Breast cancer and gynecologic cancers are the first and second most commonly occurring cancer types among women worldwide, respectively, and Merck aims to give patients facing these devastating diseases options. With more than 20 clinical trials in nearly 20,000 patients around the world, Merck is driving innovative research to purposefully advance standards of care in women's cancers. Merck's research efforts include trials focused on evaluating its medicines in earlier stages, as well as identifying novel mechanisms and new combinations with these treatments. Merck is working to develop a portfolio and pipeline to address the impact of women's cancers on patients, their families and communities globally.
About KEYTRUDA (pembrolizumab) injection for intravenous use, 100 mg
KEYTRUDA is an anti-programmed death receptor-1 (PD-1) therapy that works by increasing the ability of the body's immune system to help detect and fight tumor cells. KEYTRUDA is a humanized monoclonal antibody that blocks the interaction between PD-1 and its ligands, PD-L1 and PD-L2, thereby activating T lymphocytes which may affect both tumor cells and healthy cells.
Merck has the industry's largest immuno-oncology clinical research program. There are currently more than 1,600 trials studying KEYTRUDA across a wide variety of cancers and treatment settings. The KEYTRUDA clinical program seeks to understand the role of KEYTRUDA across cancers and the factors that may predict a patient's likelihood of benefitting from treatment with KEYTRUDA, including exploring several different biomarkers.
Merck's focus on cancer
Every day, we follow the science as we work to discover innovations that can help patients, no matter what stage of cancer they have. As a leading oncology company, we are pursuing research where scientific opportunity and medical need converge, underpinned by our diverse pipeline of more than 25 novel mechanisms. With one of the largest clinical development programs across more than 30 tumor types, we strive to advance breakthrough science that will shape the future of oncology. By addressing barriers to clinical trial participation, screening and treatment, we work with urgency to reduce disparities and help ensure patients have access to high-quality cancer care. Our unwavering commitment is what will bring us closer to our goal of bringing life to more patients with cancer.
About Merck
At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world - and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities.
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