Merck (NYSE: MRK), known as MSD outside the United States and Canada, has announced that the U.S. Food and Drug Administration (FDA) approved KEYTRUDA® (pembrolizumab) and KEYTRUDA QLEX™ (pembrolizumab and berahyaluronidase alfa-pmph) in combination with paclitaxel, with or without bevacizumab. The approval covers adults with PD-L1–positive (CPS ≥1) platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal carcinoma who have received one or two prior systemic regimens.
Phase 3 Data Demonstrate Survival Benefit
The FDA based its decision on results from the Phase 3 KEYNOTE-B96 (ENGOT-ov65) trial, presented at the 2025 ESMO Congress. In patients with PD-L1–expressing tumors (CPS ≥1), the KEYTRUDA combination reduced the risk of disease progression or death by 28% (HR=0.72; p=0.0014) compared with placebo plus chemotherapy. Moreover, it reduced the risk of death by 24% (HR=0.76; p=0.0053).
Median progression-free survival improved to 8.3 months versus 7.2 months, while median overall survival increased to 18.2 months compared with 14.0 months in the control arm.
Addressing an Area of High Unmet Need
As per the Merck Press release, experts emphasize that platinum-resistant ovarian cancer carries a poor prognosis and limited treatment options. According to Dr. Bradley Monk, the approval offers patients who have progressed on platinum-based therapy a meaningful opportunity for extended survival.
Dr. Gursel Aktan of Merck highlighted that introducing the first PD-1 inhibitor in this setting marks a significant advancement for women’s cancers and expands therapeutic possibilities.
Safety Profile and Key Considerations
Investigators evaluated safety in 463 patients with PD-L1–positive tumors. Serious adverse events occurred in 54% of patients, while 3.9% experienced fatal adverse reactions. Common side effects included diarrhea, fatigue, nausea, alopecia, peripheral neuropathy, and anemia.
Clinicians should monitor for immune-mediated reactions, infusion-related events, and other serious complications. KEYTRUDA QLEX remains contraindicated in patients with hypersensitivity to hyaluronidase components.