Biotechnology company Promega Corporation announced on Tuesday that the US Food and Drug Administration has approved its OncoMate MSI Dx Analysis System as a companion diagnostic for identifying patients with microsatellite stable endometrial carcinoma who may benefit from treatment with KEYTRUDA, Merck's anti-PD-1 therapy, in combination with LENVIMA, Eisai's tyrosine kinase inhibitor.

This marks the first FDA-approved companion diagnostic from Promega.

OncoMate MSI Dx is a PCR-based assay that evaluates microsatellite instability (MSI) status in tumour tissue, providing key insights for treatment selection and precision oncology strategies.

The approval stems from Promega's collaboration with Merck and Eisai, which co-market the KEYTRUDA plus LENVIMA regimen. The partnership aims to advance personalised medicine and improve access to molecular diagnostics that inform targeted therapy decisions.

Previously, the OncoMate MSI Dx System was cleared as the first PCR-based molecular diagnostic for identifying colorectal cancer patients for additional Lynch syndrome testing. The latest approval covers the United States and its territories, adding to prior regulatory clearances in China and the European Union.