Clinical and Pathological Features of Immune Checkpoint Inhibitor-induced Liver Injury in Comparison with Drug-induced Liver Injury and Autoimmune Hepatitis

Background and Aims: Immune checkpoint inhibitors may cause various types of organ damage as immune-related adverse events, of which, liver damage is the most common. Herein, we evaluated the clinicopathological features of immune checkpoint inhibitor-related liver injury and investigated the differences between immune checkpoint inhibitor-related liver injury and drug-induced liver injury or autoimmune hepatitis. Methods: We selected patients with ≥ grade 3 liver injury who were diagnosed with immune checkpoint inhibitor-related liver injury (n=15). Liver biopsies were performed in 10 of the 15 cases. We also selected cases in which a liver biopsy was performed and drug-induced liver injury (n=7) or autoimmune hepatitis [n=21: acute exacerbation (n=13) was diagnosed and cases of acute onset (n=8), in which liver function test results corresponded to ≥ grade 3]. Results: Portal fibrosis and periportal activity scores were significantly higher in the acute exacerbation autoimmune hepatitis group than in the other groups. Portal and lobular activity were not different between the groups. Plasma cell infiltration showed a higher trend in the autoimmune hepatitis group than in the other groups. Granuloma formations were seen in 90% of immune checkpoint inhibitor-related liver injury cases. The CD4/8 ratio was significantly lower in the immune checkpoint inhibitor-related liver injury group than in the other groups. Patients with bile duct injury had poorer response to corticosteroid therapy than those without. Conclusions: There are some obvious differences among immune checkpoint inhibitor-related liver injury, drug-induced liver injury, and autoimmune hepatitis in liver histology. Liver biopsy is helpful for the diagnosis and severity evaluation of liver injury.