Although IO’s exact role in rectal cancer treatment has not been determined to date, the 100% complete clinical response rates achieved with anti-PD1 treatment (dostarlimab) in 12 stage II–III rectal cancer patients with mismatch-repair (MMR)-deficient tumors have suggested that the exploitation of anti-tumor immunity could significantly improve rectal cancer patient prognosis [6]. Here, PDCD1 is linked to rectal cancer.