Anti-PD-1 and anti-PD-L1 drugs are overall less toxic than standard chemotherapy, but a lot of clinical and SRs have found some immune-related AEs, such as colitis, hepatitis, pneumonitis, and hypothyroidism as well as more general AEs related to immune activation, including fatigue, diarrhea, and rash, have been common.[8,28] However, the conclusions of these studies are not uniform. This evidence concerns the gene PDCD1 and hypothyroidism.