A recent systematic review and meta-analysis reported that the overall incidence rates of gastrointestinal toxicities in patients receiving anti-PD-1/PD-L1 monotherapy, ipilimumab monotherapy, and combination therapy were 1.3%, 9.1%, and 13.6%, respectively, for all grades of colitis; 0.9%, 6.8%, and 9.4%, respectively, for grade 3 or 4 colitis; and 1.2%, 7.9%, and 9.2%, respectively, for grade 3 or 4 diarrhea [96]. Here, PDCD1 is linked to colitis.