The FDA approved Merck’s Keytruda (pembrolizumab) + chemotherapy, with or without bevacizumab, for adults with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal carcinoma with PD-L1–positive tumors after 1–2 prior systemic regimens, based on Phase III KEYNOTE-B96. In PD-L1–positive disease, the regimen improved median PFS to 8.3 months vs 7.2 months and median OS to 18.2 months vs 14.0 months versus placebo.

Why It Matters To Oncology

• Establishes an immunotherapy-based regimen with a statistically meaningful survival signal in a hard-to-treat, heavily pretreated Ovarian Cancer–adjacent population (platinum-resistant epithelial ovarian/fallopian tube/primary peritoneal).

• Broadens the clinical footprint of PD-1 blockade beyond prior ovarian cancer niches, potentially reshaping sequencing decisions around anti-VEGF use (bevacizumab optional).

• Pairs therapeutic expansion with a companion diagnostic: FDA also cleared Agilent’s PD-L1 IHC 22C3 pharmDx to identify eligible patients.

The Financials

• Keytruda generated >$30B in sales last year, but Merck is approaching a 2028 patent expiration—making label expansion strategically high value.

• The approval covers both infused and subcutaneous formulations, potentially supporting site-of-care flexibility and administration economics.

• No pricing or incremental cost-effectiveness details were disclosed in the announcement.

What They're Saying

• The approval is framed as a first: KEYNOTE-B96 is described as the first time an immunotherapy-based regimen has shown such a broad benefit in this specific patient population.

• Regulators also emphasized test-and-treat alignment by clearing a companion diagnostic alongside the label.

What's Next

• Clinicians will watch for deeper subgroup detail (e.g., PD-L1 expression thresholds, bevacizumab vs no-bevacizumab outcomes, prior bevacizumab exposure) to guide regimen selection.

• Drug discovery teams will parse KEYNOTE-B96 for resistance biology in platinum-resistant disease and combinations that can extend benefit beyond PD-L1–positive tumors.

• Expect real-world uptake questions around testing workflows (22C3), toxicity management with triplet regimens, and sequencing versus other post-platinum options.