Diagnosis and follow-up of immune-related hypophysitis with MRI of pituitary gland.

Abstract

e24087 Background: Immune checkpoint inhibitors (ICIs) have transformed the prognosis of many solid malignancies. However, their use has also been associated with distinct endocrine immune-related adverse events (irAEs), hypophysitis being among the most common. Purpose: To describe in a real-world patient cohort, how ICI-induced hypophysitis is depicted on pituitary MRI and how these imaging findings are evolved overtime. Methods: A retrospective analysis of pituitary MRIs was performed on ICI-treated cancer patients who developed biochemically confirmed pituitary insufficiency from January 2016 to September 2024.The initial MRI was performed at the time of diagnosis of ICI-induced hypophysitis, and the follow-up MRI was performed at the same center and assessed by the same radiologist. Both MRIs were evaluated by a central team of radiologists, blinded to the onset of ir-hypophysitis. Results: Sixty-six ICI-treated cancer patients (median age,67 years;35 males) were biochemically diagnosed with pituitary deficiency of one or multiple axis were eligible for inclusion in our analysis. The majority received immunotherapy(70% an anti-PD-1/anti-PD-L1 ICI, and 19% anti-PD-1/anti-PD-L1 and anti-CTLA-4 combinations) for melanoma (90.9%), whereas 4.5% of cases had lung cancer, 1.5% colon cancer and 3% hepatocellular carcinoma. The initial pituitary MRI was performed on 60 patients at a median time of 2 weeks post-diagnosis of ir-hypophysitis (6 excluded due to recently administered steroids for other irAE). Abnormalities were found in 32 patients (53.3%), including enlargement (25%) or reduced enhancement of pituitary gland (10%), empty sella turcica (8.3%), heterogeneous enhancement (5%), or reduced dimensions of pituitary gland (3.3%) and slight deviation of stalk (1.7%). A 2 nd pituitary MRI assessment, after a median follow-up of 1.6 years, was available in 37 patients; 45% of them presented alteration of their initial abnormal MRI findings. Abnormalities were described in 62.2% of cases, including reduced dimensions (18.9%), or enlargement of pituitary gland (16.2%), partially empty sella turcica (16.2%), heterogeneous (8.1%) and reduced (2.7%) enhancement of pituitary gland. No ICI-regimen was associated with a specific MRI abnormality; while subjects receiving an anti-PD-1 ICI or an ICI doublet continued to show abnormal imaging at follow up in similar rates (31.8%-31.5%). Patients with multiple axes deficiencies presented an increased frequency of MRI abnormalities compared to those with isolated corticotrope deficiency in both assessments. Conclusions: MRI pituitary abnormalities were found in approximately 50% of patients with ir-hypophysitis; were not specific to the underlying malignancy and the administered ICI and may persist overtime, transforming their abnormal imaging. The other half presented normal pituitary MRI in both assessments, keeping the challenge of imaging for this irAE.