Immune checkpoint inhibitors (ICIs) are monoclonal antibodies that target down-regulators of the anti-cancer immune response and have revolutionized the treatment of a variety of malignancies. However, many immune-related adverse events, especially diarrhea and colitis, limit their use.  The incidence of immune-mediated colitis (IMC) ranges from 1%-25% depending on the type of ICI and whether they are used in combination used in combination.1 Approximately 44% of patients with advanced and metastatic cancer tumors (~260,000 patients) are eligible to receive immune checkpoint inhibitors (ICIs).2 Approximately 30% of ICI patients develop diarrhea, which can progress to colitis. The onset of diarrhea in ICI-AC patients occurs within 6-7 weeks and progressively worsens, and the progression to colitis is rapid and unpredictable. For example, in patients taking ipilimumab (Yervoy), between 25-30% of patients developed diarrhea and ~8-12% developed colitis.Moreover, the trend is towards the use of combination ICI therapies (e.g. Yervoy and Opdivo) and this will lead to a concomitant increase in both diarrhea and colitis.

Administration of corticosteroids, or treatment with certain immunosuppressive biologics, while withholding ICI therapy are recommended for grade 2 or more severe colitis (National Cancer Institute 2020).  The impact of this colitis complication and treatment may reduce the goal of progression free cancer survival. An oral, non-absorbed treatment, such as niclosamide, for grade 1 colitis (diarrhea) may prevent progression to grade 2 disease. There currently is no approved treatment for grade 1 colitis.

1 Wang et al. Patients with ICPI-induced diarrhea or colitis have improved survival outcomes. J Immunother Cancer. 2018; 6: 37. Som et al., World J Clin Cases. Feb 26, 2019; 7(4): 405-418
2 Wang DY, Ye F, Zhao S, et al. Incidence of immune checkpoint inhibitor-related colitis in solid tumor patients: a systematic review and meta-analysis. Oncoimmunology 2017; 10: e1344805; Som et al., World J Clin Cases. Feb 26, 2019; 7(4): 405-418