CD274 and pituitary tumor: Fourthly, the incomplete understanding of the microenvironment of PitNETs (which may be key for the responses to ICIs), as well as the lack of biomarkers predicting good response to ICIs in patients with PitNETs (including the positive expression of PD-L1 in pituitary tumour cells [27]), may lead to an inadequate selection of patients to receive such treatments [34,46].