The marked differences in the incidences of anti-CTLA-4 antibody-induced and anti-PD-1 or anti-PD-L1 antibody-induced hypophysitis may be attributed to functional differences in the process of T cell activation (27), and the expression of CTLA-4 in human pituitary gland cells that may be targeted by an anti-CTLA-4 antibody (28). This evidence concerns the gene CTLA4 and hypophysitis.