In a metanalysis with data from 6472 patients treated with ICIs in clinical trials, hypophysitis was found to occur more frequently in patients treated with anti-cytotoxic T-lymphocyte antigen 4 (anti-CTLA4) antibodies than in patients treated with anti-programmed death 1 (anti-PD1) or anti-programmed death ligand 1 (anti-PD-L1) monoclonal antibodies (3.8% vs. 1.1%; OR 0.29, 95% CI 0.18–0.49, p < 0.0001), whilst hypothyroidism was more common in patients treated with anti-PD1/PD-L1 than in patients treated with anti-CTLA4 antibodies (7% vs. 3.8%; OR 1.89, 95% CI 1.17–3.05, p = 0.0089) [3]. Here, CTLA4 is linked to hypothyroidism.