This increase most likely reflects wider use of ICI therapy in more cancer patients - (a) more melanoma patients (the original indication) are now treated with 2 classes of ICIs; (b) as new indications are approved for other cancers, more patients are now treated with ICIs (Table 1); and (c) more cases of anti-PD-1-induced endocrinopathies were reported in the past 3 years after their approval in 2014 (Fig. 2). Here, PDCD1 is linked to endocrine system disorder.