Dostarlimab for the first line treatment of locally advanced rectal cancer

Dostarlimab is in clinical development for the first-line treatment of locally advanced, stage 2 to 3 mismatch repair deficient (dMMR) and/or microsatellite instability-high (MSI-H) rectal cancer. Rectal cancer starts in the rectum (the back passage), which is part of the large bowel. Risk factors include age and diet or lifestyle factors. Locally advanced rectal cancer has grown through the wall of the rectum and/or spread to nearby lymph nodes. dMMR means the cancer cells have problems fixing DNA-copying mistakes and build up more mutations. MSI-H means the cancer has many mutations in small, repeated DNA sequences (microsatellites). There is a need for new first-line treatments because the current standard of care can reduce quality of life and still leads to poor outcomes for many patients.