The most common irAEs for PD-1/PD-L1 blockade are endocrine (thyroid disorders such as hypothyroidism and hyperthyroidism), gastrointestinal (diarrhea, colitis, nausea), lung (pneumonitis), skin (rash, pruritus, and vitiligo) and musculoskeletal (arthralgia, arthritis, and myalgia), and constitutional symptoms (fatigue, pyrexia, and anorexia) 34, as shown in Figure 1. Here, PDCD1 is linked to colitis.