Anticancer immunotherapy by CTLA4 blockade relies on the gut microbiota. gut metagenome

Blockade of CTLA4 by ipilimumab often results in immune-related adverse events atsites that are exposed to commensal microorganisms, mostly the gut. Patients treated withipilimumab develop antibodies to components of the enteric flora, suggesting that suchimmune reactions may contribute to colitis. Therefore, addressing the role of gut microbiota inthe immunomodulatory effects of CTLA4 blockade is crucial for the future development ofimmune checkpoint blockers in oncology.