Immune checkpoint inhibitor⇓mediated diarrhea and colitis: A clinical review

Immune-mediated diarrhea and colitis (IMDC) is among the most common immune-related adverse events in patients with cancer treated with immune checkpoint inhibitors (ICIs). Many factors will affect the risk of IMDC, including the type of ICI used, the type of underlying cancer, and patient characteristics. A recent study showed that preexisting inflammatory bowel disease significantly increases the risk of diarrhea and colitis with ICI treatment. In terms of management, early endoscopic evaluation improves clinical outcome by identifying high-risk patients who will benefit from early add-on immunosuppressants. Inflammatory markers, including fecal lactoferrin and calprotectin, are good screening tools to predict which patients are at risk for colitis. Calprotectin especially is associated with colitis outcome and can be used as a surrogate marker to follow treatment response. Corticosteroids remain the first-line medical treatment of IMDC management, and add-on therapy with vedolizumab or infliximab should be considered in selected patients. Fecal microbiota transplantation may be considered in refractory cases. The decision to resume ICI should be decided by balancing the risk of recurrent IMDC and the likelihood of benefiting from further ICI treatment. There is no clear evidence about whether the use of immunosuppressants will result in a worse cancer outcome. With emerging evidence, our understanding and management strategies are likely to evolve in the future.