Immune-related hypophysitis: An analysis of a heterogeneous entity.

Abstract

e14704 Background: Immune-checkpoint inhibitors (ICIs) have led to revolutionary breakthroughs in the management of many malignancies. With the increasing use of ICIs, immune-related adverse events (irAE) have emerged and led to significant challenges and limitations. Immune-related hypophysitis, a potentially life-threatening irAE, has limited data on its diagnosis, clinical findings, and management. This was our incentive to characterize our single-institution experience with immune-related hypophysitis over the past 5 years. Methods: We retrospectively studied a cohort of adult patients who received ICIs at the Cleveland Clinic Foundation between 2017-2022. Our search was done by utilizing an outpatient oncology pharmacy database. Analyzed ICIs included atezolizumab, nivolumab, pembrolizumab, ipilimumab, avelumab, and durvalumab. The occurrence of immune-related hypophysitis was as determined by an endocrinologist or oncologist. Results: 6,615 patients received ICIs from 2017-2022, of which 27 patients were diagnosed with hypophysitis. Immune-related hypophysitis occurred with ICI monotherapy in 44.4% and combined therapy (ipilimumab and nivolumab) in 55.5%. The most commonly implicated agents were ipilimumab (74%), followed by nivolumab (59.3%), pembrolizumab (18.5%), and durvalumab (3.7%). In patients receiving ipilimumab-nivolumab, hypophysitis was detected after a median duration of 65 days (range: 29-163 days) from ICI initiation, compared to 58 days (38-112) with ipilimumab alone and 155 days (8-294) with pembrolizumab. Hypophysitis was grade 1 in 18.5%, grade 2 in 29.6%, grade 3 in 37%, and grade 4 in 14.8% of all patients. No hypophysitis-related deaths occurred. Signs and symptoms included constitutional symptoms (fever, anorexia, myalgia) in 88.89%, severe/intractable headaches in 40.7%, gastrointestinal complaints in 29.6%, dermatologic findings in 7.4%, visual symptoms in 7.4%, and syncope in 3.7% of all patients. Lab findings included abnormalities of TSH in 77.78%, ACTH in 70.60%, FSH and/or LH in 52.63%, and a positive ACTH stimulation test in 69.3%. Imaging findings were present in 62.5% of patients, and most commonly revealed pituitary gland enlargement, enhancement, or stalk thickening on brain/pituitary MRI. Treatment included glucocorticoid replacement in 92.6%, thyroid replacement in 40.7%, and testosterone in 7.4% of patients. All patients remained on glucocorticoid therapy indefinitely after hypophysitis was diagnosed. ICIs were momentarily held in 22.2% and discontinued in 51.86% of patients, while 25.9% of patients did not experience treatment interruptions. Conclusions: Immune-related hypophysitis is an uncommon irAE that presents with variable clinical and diagnostic findings. Nonetheless it is a cause of permanent glucocorticoid dependence. Healthcare professionals should be aware of this entity so treatment can be promptly started.