THU093 Pituitary Enlargement And Hypopituitarism In Patients Treated With Immune Checkpoint Inhibitors: Two Sides Of The Same Coin?

Disclosure: S. Menotti: None. S. Chiloiro: None. A. Giampietro: None. A. Bianchi: None. F. Angelini: None. T. Tartaglione: None. G. Antonini Cappellini: None. F. De Galitiis: None. E. Rossi: None. G. Schinzari: None. A. Scoppola: None. A. Pontecorvi: None. L. De Marinis: None. M. Fleseriu: None. Introduction: Immune checkpoint inhibitors hypophysitis (IIHs) represents an emerging problem in cancer patients treated with immune checkpoint inhibitors (ICIs). In this study, we aimed to describe the clinical and molecular features, therapeutic management and outcome of a multicentre series of IIHs. Material and Methods: Demographic and clinical features were retrospectively collected for all cases. Patients with new onset of pituitary disfunction during ICI treatment underwent contrasted pituitary magnetic resonance images (MRI). IIH was diagnosed if presence of typical radiological finding of hypophysitis. The immunotherapy induced hypopituitarism was defined as patients without the radiological finding of hypophysitis. Anti-pituitary and anti-hypothalamus autoantibodies were also measured. Results: Nine patients were included; 7 with metastatic melanoma, 1 metastatic lung adenocarcinoma and 1 metastatic kidney adenocarcinoma. Six patients were treated with nivolumab and three with ipilimumab. All patients had new-onset asthenia. Secondary hypoadrenalism was diagnosed in all patients. Pituitary MRI showed pituitary enlargement in 2 cases and no abnormalities in the other 7 cases. APA were positive in 57.1% and AHA in 85.7% of cases. Multidisciplinary treatments were established by neuro-endocrinologist and oncologists: all patients were treated with hydrocortisone replacement; ICI was withdrawn in 2 cases, until the clinical stabilization of the hypoadrenalism. None of the patients were prescribed immunosuppressive high dose glucocorticoids (over 40 mg /day). At follow-up, hypoadrenalism persisted in all cases. Pituitary enlargement (hypophysitis per se) on MRI spontaneously recovered in the two affected patients. We found that the typical features of hypophysitis involved more frequently females in our study and in patients treated with ipilimumab. Conclusion: Although this study did not clarify if autoimmune secondary hypoadrenalism and ICI hypophysitis on brain imaging are two sides of the same disease, our preliminary data underline the need for molecular studies of IIHs and of autoimmune ICIs-related hypopituitarism, especially central hypoadrenalism. Presentation: Thursday, June 15, 2023