To analyze the clinical characteristics of programmed death-1(PD-1)/programmed death-ligand 1(PD-L1) inhibitors-induced hypophysitis in patients with malignant tumors, and to improve the understanding of this disease.

The clinical manifestations, laboratory tests, and imaging features of 18 cases of PD-1/PD-L1 inhibitors-related hypophysitis cases treated in recent 3 years were analyzed retrospectively.

Among the 18 patients(0.49%, 18/3 689) with PD-1/PD-L1 inhibitors-associated hypophysitis, there were 11 males and 7 females, with the average age of(58.6±10.3) years old. There were 6 cases treated with Sindilizumab, 6 cases of Pabolizumab, and 3 cases of Duvaliumab, acounting for 83.3%(15/18). The median time to diagnosis of hypophysitis was 5.9(3.5, 9.6)months, which was related to the type of PD-1/PD-L1 inhibitors. The main clinical manifestations were fatigue, poor appetite, nausea(72.2%, 13/18), with 4 patients experiencing coma and 15 cases of hyponatremia(83.3%). The incidence of adrenocorticotropic hormone(ACTH) deficiency, thyroid stimulating hormone(TSH) deficiency, gonadotropins deficiency, growth hormone(GH) deficiency and hyperprolactinemia were 100%, 27.8%, 16.7%, 11.1% and 44.4%, respectively. No posterior pituitary was involved. There was no statistical difference between male and female patients with pituitary inflammation. 53.3% of the patients had no abnormal pituitary magnetic resonance imaging(MRI), and the rest were mildly abnormal, without pituitary enlargement. There were 5 patients with primary thyroid involvement and 2 patients with damaged pancreas. Four cases (22.2%) of immune-related reactions (irAEs) were grade 3 and above according to the Common Terminology Criteria for adverse Events (cTCAE), and the rest of the patients were CTCAE grade 1-2.

When patients receiving PD-1/PD-L1 inhibitors present with symptoms such as fatigue, poor appetite, and hyponatremia, caution should be exercised for the possibility of drug-related hypophysitis. Hypophysitis induced by PD-1/PD-L1 inhibitors primarily affects the anterior pituitary lobe with a decrease in ACTH hormone levels, while the posterior lobe is less affected, and there is no significant enlargement of the pituitary gland. Physiological doses of glucocorticoids can effectively alleviate symptoms.

Malignant tumor; PD-1/PD-L1 inhibitors; Hypophysitis; Glucocorticoid