The FDA has approved pembrolizumab (Keytruda) and its subcutaneous version, Keytruda Qlex, for adults with platinum-resistant ovarian, fallopian tube, or primary peritoneal cancer. The approval is for patients whose tumors test positive for PD-L1 (Combined Positive Score of 1 or higher) and who have already received one or two prior treatment regimens.
The decision is based on results from the Phase 3 KEYNOTE-B96 trial. In patients with PD-L1–positive tumors, adding pembrolizumab to paclitaxel (with or without bevacizumab) improved progression-free survival to 8.3 months compared with 7.2 months for the placebo group. Overall survival also improved to 18.2 months compared with 14.0 months. The FDA also approved a companion diagnostic test, the PD-L1 IHC 22C3 pharmDx assay, to help identify eligible patients.
Keytruda can be given intravenously at 200 mg every 3 weeks or 400 mg every 6 weeks. The subcutaneous version is given at 395 mg/4,800 units every 3 weeks or 790 mg/9,600 units every 6 weeks. Treatment continues until the cancer progresses or for up to 24 months.
Side effects are similar to previous pembrolizumab studies. Because it works by activating the immune system, it can cause inflammation in organs such as the lungs, liver, or intestines. Common side effects include nausea, low white blood cell counts, high blood pressure, fatigue, and diarrhea. Doctors need to monitor liver, kidney, and thyroid function during treatment, and there are warnings about risks during pregnancy and in patients undergoing stem cell transplants.