PDCD1 and rectal cancer: As a result, ICIs have become the standard of care for patients with MSI-H/dMMR metastatic colorectal disease.1, 2, 3 In rectal cancer, the efficacy of ICIs has been further highlighted in a recent phase II trial, where single-agent programmed cell death protein 1 (PD-1) dostarlimab led to a 100% clinical complete response rate in all 49 patients who completed treatment and were managed non-operatively.4