Agilent Technologies (NYSE:A) announced today that the U.S. Food and Drug Administration (FDA) has approved its PD-L1 IHC 22C3 pharmDx as the first and only companion diagnostic to identify first-line patients with epithelial ovarian cancer (EOC) eligible for Merck’s blockbuster immunotherapy, KEYTRUDA.
This milestone is a significant win for precision medicine in a field where therapeutic options have historically been limited.
The diagnostic tool allows pathologists to measure PD-L1 protein expression levels—specifically requiring a Combined Positive Score (CPS) ≥ 1—at the time of diagnosis, ensuring that patients who are most likely to benefit from immunotherapy are identified early in their treatment journey.
The FDA's decision was bolstered by the results of the KEYNOTE-B96 clinical trial.
In the study, patients with tumors expressing PD-L1 (CPS ≥ 1) showed a median progression-free survival (PFS) of 8.3 months when treated with pembrolizumab, compared to 7.2 months in the placebo arm.
With ovarian cancer causing over 12,000 deaths in the U.S. in 2025, this tool addresses a critical unmet need in oncology.
This marks the seventh FDA-approved companion diagnostic indication for the 22C3 pharmDx assay, which is already used to guide treatment for lung, breast, and gastric cancers.