MSI-H/dMMR Locally Advanced Rectal Adenocarcinoma

Observation and evaluation of the safety and efficacy of PD-1 antibody combined with IBI310 and neoadjuvant chemotherapy in the treatment of locally advanced rectal cancer Primary objectives: Pathological complete response (pCR) rate; Secondary objectives: Treatment-related adverse events (CTCAE 5.0), clinical complete response (cCR) rate, major pathological response (MPR) rate, R0 resection rate, sphincter preservation rate, surgical complications, 3-year disease-free survival (DFS), and overall survival (OS);