PDCD1 and colitis: Regarding safety, TRAEs were generally tolerable; however, the incidence of irAEs was higher in the PD-1 inhibitor combined with chemotherapy group, including hypothyroidism, hyperthyroidism, pneumonitis, colitis, thyroiditis, adrenal insufficiency, hepatitis, severe skin reactions, increased amylase, rash, etc. The activation of the immune system by ICIs can lead to an increased occurrence of inflammation or irAEs.