Roche announced the European Union In Vitro Diagnostic Regulation (IVDR) approval of several label expansions for the VENTANA MMR RxDx Panel, an immunohistochemistry (IHC) companion diagnostic test that aids in identifying a cancer patient's mismatch repair (MMR) status. MMR is a process that scans a person's genetic code and fixes errors to prevent mutations that can lead to cancer. The test evaluates a panel of MMR proteins in tumours to provide this important treatment information to clinicians.

The VENTANA MMR RxDx Panel is now available in countries regulated by IVDR as a companion diagnostic for the following therapies and cancer types: KEYTRUDA (pembrolizumab), Merck & Co. Inc., Rahway, NJ, USA's anti-PD-1 therapy: For the treatment of mismatch repair deficient (dMMR) tumors in certain adults with: metastatic colorectal cancer; advanced or recurrent endometrial carcinoma; unresectable or metastatic gastric, small intestine or biliary cancer. IMFINZI (durvalumab), AstraZeneca's anti-PD-L1 therapy: For adult patients with dMMR primary advanced or recurrent endometrial cancer.

IMFINZI + LYNPARZA (olaparib), AstraZeneca's anti-PD-L1 therapy and PARP inhibitor: For adult patients with mismatch repair proficient (pMMR) primary advanced or recurrent endometrial cancer. JEMPERLI (dostarlimab-gxly), GSK's anti-PD-1 therapy: for dMMR patients with endometrial cancer. The VENTANA MMR RxDx Panel is intended for the assessment of expression of MMR proteins in formalin-fixed, paraffin-embedded (FFPE) tumour tissue stained with OptiView DAB IHC Detection Kit and ancillary reagents in the panel for VENTANA anti-MLH1 (M1), VENTANA anti-MSH2 (G219-1129) and VENTANA anti-MSH6 (SP93), and OptiView DAB IHC Detection Kit with the OptiView Amplification Kit and ancillary reagents for VENTANA anti-PMS2 (A16-4) on a BenchMark ULTRA instrument.

MMR proteins have been clinically proven to be predictive biomarkers for PD-1 targeted therapy; specifically, a loss of expression of one or more MMR proteins might predict an increased likelihood of response to such therapy. PD-1 inhibitors can be effective in cancers with MMR deficiency. MMR is a conserved molecular mechanism that functions to correct the improper base substitutions that spontaneously occur during DNA replication.

Defects in the MMR machinery have been attributed to mutations in the MMR proteins.