Checkpoint Inhibitor Colitis Shows Drug-Specific Differences in Immune Cell Reaction That Overlap With Inflammatory Bowel Disease and Predict Response to Colitis Therapy

Abstract Objectives Checkpoint inhibitor (CPI)–associated colitis can limit therapy and has resemblance to inflammatory bowel disease (IBD). Studies exploring mechanistic similarities between these colitides are limited, yet therapeutic targets for either disorder could emerge from shared pathophysiology. Methods The morphology content of colonic biopsy specimens anti–CTLA-4 anti–PD-1/PD-L1 antibody-treated patients with CPI were compared initial IBD. Predictors the need infliximab sought in patients. Results Biopsy showed significantly lower chronicity scores similar activity Anti–CTLA-4 IBD groups equivalent CD8, CD4, PD-1, PD-L1 expression, while FoxP3 CD68 higher specimens. Anti–PD-1/PD-L1 group had PD-1 FoxP3, PD-L1, than CD8/FoxP3 ratios among requiring those responding steroids. Conclusions proinflammatory immune phenotype anti–CTLA-4–associated significant overlap may predict response CPI-associated colitis.