Incidence and risk factors of immune checkpoint inhibitor-induced colitis in Korean patients with cancer.

Background/aims: Immune checkpoint inhibitors (ICIs) are effective in treating cancer. However, various immune-related adverse events (irAEs) have become prevalent, with ICI-induced colitis being the most common gastrointestinal irAE. Thus, we aimed to investigate the incidence and risk factors of ICI-induced colitis in Korean patients with cancer.

Methods: This retrospective study included patients treated with ICIs between October 2015 and June 2022 in two tertiary referral centers in Daegu, Korea. The incidence of ICI-induced colitis was determined using electronic medical records. Risk factors for ICI-induced colitis were identified using univariate and multivariate logistic regression analyses.

Results: We included 1,478 patients with ICI-treated cancer. The incidence of ICI-induced colitis was 3.5% (n = 52/1,478). Multivariate logistic regression analysis showed that the combination of nivolumab and ipilimumab was a risk factor for ICI-induced colitis (p = 0.006; odds ratio, 9.768; 95% confidence interval, 1.93-49.30).

Conclusion: ICI-induced colitis had an incidence rate of 3.5% and was associated with the combination of nivolumab and ipilimumab. Most patients with ICI-induced colitis developed mild symptoms that improved with supportive care alone, making ICI therapy resumption possible.