Neoadjuvant Envafolimab in Resectable and Locally Advanced MSI-H/dMMR Rectal Cancer

Patients will receive single drug therapy of Envafolimab (300mg) once every two weeks. Patients who do not have tumor regression after 3 months of treatment should be judged by the investigator whether to adopt standard chemoradiotherapy plus surgery. Patients with tumor regression should continue to receive Envafolimab therapy until 6 months. For patients who do not reach complete clinical response (cCR) after 6 months of treatment, the investigator shall determine whether to perform standard chemoradiotherapy or radical surgery. For patients who reach cCR, they could receive the observation waiting or local resection which depend on the investigator. Patients should be followed up until reaching cCR or 3 years after surgery.