Ipilimumab-Induced Hypophysitis: A Detailed Longitudinal Analysis in a Large Cohort of Patients With Metastatic Melanoma

Context: Ipilimumab (Ipi) is approved by the Food and Drug Administration for the treatment of unresectable or metastatic melanoma. Little is known about Ipi-induced hypophysitis (IH), an important treatment complication. Objective: The objectives of the study were as follows: 1) to examine the prevalence of IH, 2) to characterize the clinical course and treatment outcomes in IH, 3) to identify the risk factors for the development of IH, and 4) to determine optimal strategies for the management of IH. Design: This was a retrospective review. Setting: The study was conducted at a tertiary referral center. Subjects: One hundred fifty-four adult patients with metastatic melanoma were evaluated at Massachusetts General Hospital and were treated with Ipi between March 2008 and December 2013. Intervention(s): The intervention included treatment with Ipi. Main Outcome Measure(s): Pituitary magnetic resonance imaging, pituitary hormone assessment, and patient survival were measured. Results: IH was diagnosed in 17 patients (11%). Male gender (P = .02) and older age (P = .005), but not the cumulative dose of Ipi, were risk factors for IH. All patients with IH had anterior hypopituitarism (none had diabetes insipidus). Hypopituitarism was persistent in most individuals (76%). Diffuse pituitary enlargement was observed exclusively in all cases of IH and, upon retrospective review of magnetic resonance imaging scans, this finding preceded the clinical diagnosis of hypophysitis in eight patients. Pituitary enlargement resolved rapidly (within 40 d in seven of seven patients). Median survival in patients with IH was 19.4 vs 8.8 months (P = .05) in the remainder of the cohort. Conclusions: Male gender and older age are risk factors for IH. Pituitary enlargement is sensitive and specific for IH in the appropriate setting, can precede the clinical diagnosis, and resolves rapidly. Anterior pituitary function recovery is uncommon. The incidence of hypophysitis may positively predict survival in melanoma patients treated with Ipi.