Merck's KEYNOTE-B96 Trial Achieves PFS Endpoint in Platinum-Resistant Ovarian Cancer

Merck, operating under the name MSD outside the U.S. and Canada, has announced positive results from the Phase 3 KEYNOTE-B96 trial, also referred to as ENGOT-ov65. This study, focused on treating patients with platinum-resistant recurrent ovarian cancer, met its primary endpoint, which is progression-free survival. The trial also achieved a secondary endpoint of overall survival in patients whose tumors express PD-L1. The treatment under investigation involves KEYTRUDA® (pembrolizumab), an anti-PD-1 therapy by Merck, combined with chemotherapy (paclitaxel), with or without bevacizumab.

The trial showed promising outcomes in terms of progression-free survival, regardless of PD-L1 status, when compared to a placebo combined with chemotherapy, with or without bevacizumab. The safety profile of KEYTRUDA in this context remained consistent with previous studies, and no new safety concerns were identified. The detailed results are expected to be shared at an upcoming medical gathering and with regulatory bodies globally.

Dr. Gursel Aktan, Vice President of Global Clinical Development at Merck Research Laboratories, emphasized that this is the first instance where a KEYTRUDA-based regimen has demonstrated the capability to extend the lives of patients with platinum-resistant ovarian cancer. Additionally, it marks the first time an immune checkpoint inhibitor-based regimen has shown a survival benefit in ovarian cancer, highlighting a significant advancement in treatment options for this challenging condition.

Currently, KEYTRUDA is not approved for ovarian cancer treatment. However, LYNPARZA® (olaparib), another drug co-developed by AstraZeneca and Merck, has received approval in the U.S. for three ovarian cancer indications. These include first-line maintenance treatment for BRCA-mutated advanced ovarian cancer following platinum-based chemotherapy, HRD-positive advanced ovarian cancer in combination with bevacizumab, and maintenance treatment for BRCA-mutated recurrent ovarian cancer.

In 2024, Merck announced the initiation of the Phase 2/3 REJOICE-Ovarian01 trial. This study will evaluate raludotatug deruxtecan (R-DXd), a potential first-in-class CDH6 directed DXd antibody-drug conjugate discovered by Daiichi Sankyo, developed in collaboration with Merck, targeting platinum-resistant ovarian cancer.

The KEYNOTE-B96 or ENGOT-ov65 trial is a randomized, double-blind study sponsored by Merck, carried out in collaboration with European Network for Gynecologic Oncology Trial (ENGOT) groups. This trial is exploring the efficacy of combining KEYTRUDA with chemotherapy, with or without bevacizumab, against a placebo plus chemotherapy, for platinum-resistant recurrent ovarian cancer patients. The trial enrolled around 643 participants, who were randomly assigned to receive either KEYTRUDA or a placebo, both in combination with chemotherapy, with or without bevacizumab.

Ovarian cancer typically originates in the fallopian tubes or on the ovarian surface and is the third most common gynecologic cancer globally, ranking as the seventh most common cancer in women. In 2022, approximately 324,603 women were diagnosed worldwide, and about 206,956 succumbed to the disease. In the United States, projections for 2025 estimate around 20,890 new ovarian cancer cases and about 12,730 deaths. The primary aim of initial treatments is to delay disease progression, aiming for long-term remission.

Merck remains committed to advancing research in women's cancers, striving to expand treatment options and improve outcomes for patients with breast and gynecologic cancers. These cancers rank as the first and second most common cancer types among women globally. Through over 20 clinical trials involving more than 18,000 participants worldwide, Merck is dedicated to elevating standards of care in women's cancers, exploring its medications in earlier stages, and identifying novel mechanisms and combinations for treatment. The company's efforts focus on addressing the impact of these cancers on patients and their communities globally.

KEYTRUDA, Merck’s prominent immunotherapy, increases the immune system's ability to detect and fight tumor cells by blocking interactions between PD-1 and its ligands. Merck currently leads one of the largest immuno-oncology clinical research programs, with over 1,600 trials exploring KEYTRUDA’s potential across various cancers and treatment settings.