Delayed immune-mediated hepatitis after three cycles of pembrolizumab for the treatment of sinonasal melanoma.

Abstract

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies that induce the anti-tumor effects of T cells by targeting co-inhibitory immune checkpoints. The development of ICIs has revolutionized the clinical practice of oncology, leading to significant improvements in outcomes; therefore, ICIs are now standard care for various types of solid cancers. 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. To date, there have been limited reports about delayed immune-mediated hepatitis (IMH) and histopathologic findings. Herein, we present a case of delayed IMH that occurred 3 months after the last dose of pembrolizumab, including histopathologic findings of the liver. This case suggests that ongoing surveillance for immune-related adverse events is required, even after cessation of ICI treatment.