The VENTANA MMR RxDx Panel is the first and only immunohistochemistry-based assay panel approved to identify endometrial carcinoma patients eligible for treatment with dostarlimab. Endometrial cancer (EC) is the most common gynaecological malignancy in the U.S. and the fourth most common cancer in women in North America.1,2 It has the highest rates of mismatch repair (MMR) deficiency of all tumors (20-40%).3,4,5 There are limited treatment options for women whose disease progresses on or after first-line therapy.6