Unlike hypophysitis induced by CTLA-4 inhibitors, which is typically characterized by direct lymphocytic infiltration of the pituitary, PD-1 inhibitor-associated hypophysitis is thought to be mediated by a different immune mechanism. Studies suggest that PD-1 blockade leads to sustained T-cell activation and an increase in autoreactive lymphocytes, which may target pituitary-specific antigens [7]. Here, CTLA4 is linked to hypophysitis.