POU1F1 and pituitary gland adenoma: The authors proposed the use of PD-1 inhibitors in combination with radiotherapy or temozolomide for the treatment of aggressive PPA (Wang et al., 2017) John et al. also found a higher incidence of significant PD-L1 in PIT-1-positive multihormone tumors than in other pituitary adenomas, and PD-L1 overexpression was very rare in ACTH and gonadotropin cells.