Can Immune Checkpoint Inhibitors Induce Microscopic Colitis or a Brand New Entity?

Area of Science:

• Gastroenterology
• Oncology
• Immunology

Background:

• Microscopic colitis (MC) is a recognized pattern of injury in immune checkpoint inhibitor (ICPI)-induced colitis.
• Characterizing ICPI-induced MC is crucial for understanding its unique risk factors, treatment, and outcomes.

Purpose of the Study:

• To compare risk factors, treatments, endoscopic features, and clinical outcomes of ICPI-induced MC with MC in cancer patients without ICPI exposure and in noncancer patients.
• To elucidate the distinct characteristics of MC associated with ICPI therapy.

Main Methods:

• Retrospective chart review of MC patients from January 2012 to January 2018.
• Categorization into three groups: ICPI-exposed cancer patients, non-ICPI cancer patients, and noncancer patients.
• Comparison of risk factors, colitis treatments, endoscopic findings, and clinical outcomes.

Main Results:

• Proton pump inhibitor use was higher in the ICPI-induced MC cohort (P = 0.040).
• Mucosal abnormalities were more common endoscopically in ICPI-induced MC (P = 0.106).
• ICPI-induced MC patients required more steroid and immunosuppressive treatments (all P < 0.001) and had higher hospitalization rates (P < 0.001).

Conclusions:

• ICPI-induced MC exhibits a more aggressive disease course compared to MC without ICPI exposure.
• Treatment for ICPI-induced MC necessitates potent immunosuppressive regimens and increased hospitalization.