Summary
The purpose of this study is to investigate dostarlimab monotherapy in participants with
locally advanced Mismatch-repair deficient (dMMR)/Microsatellite instability-high (MSI-H)
rectal cancer who have received no prior treatment. Participants who achieve complete
clinical response (cCR) following dostarlimab treatment will undergo non-operative
management (NOM), including close surveillance for recurrent disease. The goal of the
study is to determine if Dostarlimab therapy alone is an effective treatment that can
allow participants to avoid chemotherapy, radiation, and surgery.