S5844 Late Onset Immune Mediated Hepatitis Emerging After Pembrolizumab: A Case Report

Introduction: Immune checkpoint inhibitors have transformed cancer therapy by harnessing the body’s immune system to target malignancies. Hepatitis is one of the serious immune-related adverse events. However, delayed-onset hepatitis induced by immune-checkpoint inhibitors (ICIs) is rare. Immune checkpoint inhibitors (ICIs) have been increasingly used for multiple cancer types in the past decade. ICIs include CTLA-4 inhibitors (ipilimumab) and the PD-1 and PD-L1 inhibitors (nivolumab and pembrolizumab). It can occur 8-12 weeks after the initiation of ICI and presents with elevation of transaminases. Case Description/Methods: A 76-year-old woman who has a history of metastatic renal cell carcinoma and currently on pembrolizumab immunotherapy, presented to the ED with generalized weakness, shortness of breath, and fatigue. She was recently started on pembrolizumab after a previous intolerance in 2021 secondary to immune related colitis. Workup in the emergency room revealed transaminitis. Solu-Medrol started in the emergency room. The patient received a pulse dose of 125 mg of solumerol followed by 40 mg intravenous twice daily. We discharged her on oral prednisone for 2 weeks. Her liver function tests showed a significant improvement on follow up, confirming the immune mediated etiology. Discussion: ICI induced hepatitis is usually asymptomatic and discovered incidentally through abnormal liver function test. Immune-related adverse events, the unique toxicity profiles of ICIs, usually develop 4-12 weeks after initiation of ICI treatment; however, some cases can occur >3 months after cessation of ICI treatment. Timely identification and treatment of this condition is crucial as it can progress to fulminant liver failure. Hepatotoxicity is not uncommon secondary to ICI treatment. It can occur 8-12 weeks after the initiation of ICI and presents with elevation of transaminases.