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World J Gastrointest Pathophysiol. Sep 10, 2019; 10(2): 17-28
Published online Sep 10, 2019. doi: 10.4291/wjgp.v10.i2.17
Immune checkpoint inhibitor-induced diarrhea/colitis: Endoscopic and pathologic findings
Tsutomu Nishida, Hideki Iijima, Shiro Adachi
Tsutomu Nishida, Department of Gastroenterology, Toyonaka Municipal Hospital, Osaka 560-8565, Japan
Hideki Iijima, Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
Shiro Adachi, Department of Pathology, Toyonaka Municipal Hospital, Osaka 560-8565, Japan
Author contributions: Nishida T wrote the initial draft of the manuscript; Adachi S wrote the pathology section; Iijima H and Adachi S critically reviewed the manuscript.
Conflict-of-interest statement: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Tsutomu Nishida, MD, PhD, Doctor, Department of Gastroenterology, Toyonaka Municipal Hospital, 4-14-1 Shibahara, Toyonaka, Osaka 560-8565, Japan. tnishida.gastro@gmail.com
Telephone: +81-6-68430101 Fax: +81-6-68583531
Received: April 28, 2019
Peer-review started: May 9, 2019
First decision: June 6, 2019
Revised: June 30, 2019
Accepted: August 21, 2019
Article in press: August 21, 2019
Published online: September 10, 2019
Processing time: 134 Days and 21.1 Hours
Abstract

The indications of immune checkpoint inhibitors (ICPIs) for cancer treatment have rapidly expanded, and their use is increasing in clinical settings worldwide. Despite the considerable clinical benefits of ICPIs, frequent immune-related adverse events (irAEs) have become nonnegligible concerns. Among irAEs, ICPI-induced colitis/diarrhea is frequent and recognized not only by oncologists but also by gastroenterologists or endoscopists. The endoscopic findings show similarity to those of inflammatory bowel disease to a certain extent, particularly ulcerative colitis, but do not seem to be identical. The pathological findings of ICPI-induced colitis may vary among drug classes. They show acute or chronic inflammation, but it may depend on the time of colitis suggested by colonoscopy, including biopsy or treatment intervention. In the case of chronic inflammation determined by biopsy, the endoscopy findings may overlap with those of inflammatory bowel disease. Here, we provide a comprehensive review of ICPI-induced colitis based on clinical, endoscopic and pathologic findings.

Keywords: Immune checkpoint inhibitor; Colitis; Diarrhea; Endoscopic; Pathologic

Core tip: Immune checkpoint inhibitor (ICPI)-induced colitis/diarrhea is frequent and recognized not only by oncologists but also by gastroenterologists or endoscopists. The endoscopic findings resemble those of inflammatory bowel disease to a certain extent, particularly ulcerative colitis, but are not identical. The pathological findings of ICPI-induced colitis may vary among drug classes. The findings show acute or chronic phases but may depend on the diagnostic timing or treatment intervention. Colonoscopy with biopsy is necessary to confirm ICPI-induced colitis, and early evaluation may avoid exacerbating or prolonging colitis due to treatment resistance.