In a systematic review and meta-analysis including data from 38 randomized clinical trials comprising 7551 patients investigating the use of ICIs in the treatment of various cancer types, irH incidence was reported to range from 1.5% to 13.3% in patients treated with CTLA-4 antibodies and 0.3–3% in those with PD-1 inhibitors (Barroso-Sousa et al. 2018). Here, PDCD1 is linked to cancer.