Merck (NYSE:MRK) reached a historic milestone in oncology today as the FDA approved KEYTRUDA (pembrolizumab) and its new subcutaneous twin, KEYTRUDA QLEX, for the treatment of platinum-resistant ovarian cancer.
This marks the first time a PD-1 inhibitor has been authorized for this notoriously difficult-to-treat patient population, offering a new lifeline to those who have exhausted standard platinum-based therapies.
The approval, which includes fallopian tube and primary peritoneal cancers, specifically targets adults whose tumors are PD-L1 positive (CPS ≥1).
In a major win for patient quality of life, the new QLEX formulation—developed using Halozyme’s hyaluronidase technology—can be administered as a simple under-the-skin injection in as little as one to two minutes, compared to the traditional 30-minute intravenous (IV) infusion.
The FDA’s decision was underpinned by the Phase 3 KEYNOTE-B96 trial (also known as ENGOT-ov65), which demonstrated that adding Keytruda to paclitaxel (with or without bevacizumab) significantly extended lives.
For the roughly 70-80% of advanced ovarian cancer patients who experience recurrence, "platinum resistance" has long been a clinical dead end.
The approval of a subcutaneous option is particularly transformative for the 2026 healthcare landscape, as it allows clinics to free up infusion chairs and reduces patient "chair time" by nearly 50%.
While the results are groundbreaking, the regimen carries a high rate of immune-mediated side effects.
Serious adverse reactions occurred in 54% of trial participants, with pneumonia and urinary tract infections being the most frequent.