Merck’s Keytruda gains EU approval as first PD-1 therapy for hard-to-treat ovarian cancer

Merck (NYSE:MRK) has secured a landmark regulatory approval in the European Union for its blockbuster immunotherapy Keytruda, marking the region’s first PD-1 inhibitor authorized to treat a particularly aggressive form of ovarian cancer.

The European Commission’s decision clears Keytruda (pembrolizumab) for use in combination with paclitaxel, with or without bevacizumab, for adults with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal carcinoma.

The authorization is specifically targeted at patients whose tumors express the PD-L1 biomarker with a Combined Positive Score (CPS) of 1 or greater, and who have previously undergone one or two systemic treatment regimens.

The approval addresses a critical gap in the oncology landscape, as patients with platinum-resistant disease—where the cancer no longer responds to standard chemotherapy—historically face a poor prognosis and limited therapeutic alternatives.

Dr. Nicoletta Colombo of the European Institute of Oncology noted that the regimen represents a "crucial new treatment option" for a community with high unmet needs.

The EU's move was underpinned by data from the Phase 3 KEYNOTE-B96 trial.

In the study, the Keytruda-based combination reduced the risk of death by 24% compared to chemotherapy alone.

Patients treated with the immunotherapy regimen showed a median overall survival of 18.2 months, compared to 14 months for those in the control group.

Furthermore, the risk of disease progression or death was reduced by 28%, with a median progression-free survival of 8.3 months.

Beyond the standard intravenous delivery, the approval also encompasses the subcutaneous formulation, Keytruda SC.

This version, which utilizes berahyaluronidase alfa technology, is marketed as Keytruda QLEX in the United States and offers the potential for faster administration.