Merck & Co. Inc. (MRK) just added another notch to Keytruda's belt. The FDA approved the cancer immunotherapy on Wednesday for use in previously treated ovarian cancer patients, marking yet another expansion for what's already one of the pharmaceutical industry's biggest revenue generators.
The approval covers both Keytruda (pembrolizumab) and Keytruda Qlex (pembrolizumab and berahyaluronidase alfa-pmph) when combined with paclitaxel, with or without bevacizumab. It's specifically for adults with PD-L1-positive platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal carcinoma who've already been through one or two prior treatment regimens.
If you're wondering what Keytruda Qlex is, it's the subcutaneous injection version that the FDA cleared back in September 2025. Think of it as the one-minute cancer shot alternative to traditional IV administration, now approved across most solid tumor indications.
What the Trial Actually Showed
The approval stems from the Phase 3 KEYNOTE-B96 trial (also called ENGOT-ov65), and the numbers are pretty compelling. Patients who received Keytruda plus paclitaxel, with or without bevacizumab, saw their risk of disease progression or death drop by 28% compared to those getting placebo plus paclitaxel.
More importantly, the Keytruda regimen cut the risk of death by 24% overall. In patients whose tumors expressed PD-L1 (CPS ≥1), median progression-free survival hit 8.3 months versus 7.2 months for the placebo group. That might sound like a modest difference, but for platinum-resistant ovarian cancer, every additional month matters.
Overall survival told a similar story. Patients on the Keytruda regimen lived a median of 18.2 months (95% CI, 15.3-21.0) compared to 14.0 months (95% CI, 12.5-16.1) for those on placebo. That's an extra four months of survival in a patient population with historically limited treatment options.
The Blockbuster Keeps Growing
This approval matters for Merck (MRK) because Keytruda is basically carrying the company's growth story. The drug pulled in $8.37 billion in global sales during the fourth quarter of 2025 alone, representing a 7% year-over-year jump. That growth comes from exactly these kinds of expansions into earlier-stage indications and sustained demand in metastatic cancer treatment.
Keytruda's approval list keeps getting longer. Back in June 2025, the FDA approved it for resectable locally advanced head and neck squamous cell carcinoma patients with PD-L1-expressing tumors, making it the first immunotherapy approved for use around surgery in that indication. The drug gets used as a single agent for neoadjuvant treatment, then continued as adjuvant treatment combined with radiotherapy with or without cisplatin, and finally as a single agent again.
Merck shares were up 0.22% at $117.00 at the time of the announcement on Wednesday.
