Features of Microscopic Colitis in Cancer Patients Receiving Immune Checkpoint Inhibitors

Abstract

Introduction: Microscopic colitis (MC) has been described as one pattern of injury in immune checkpoint inhibitor (ICPI)-induced colitis. However, very little information is available in the medical literature regarding MC characteristics in patients receiving ICPI. We aimed to characterize ICPI-induced MC by exploring risk factors, colitis treatment, endoscopic features, and clinical outcomes and comparing them with those of patients who had MC without ICPI exposure. Methods: We studied consecutive patients with MC from January 2012 to January 2018. Patients were grouped as cancer patients with or without ICPI exposure or non-cancer patients. Medical charts were reviewed to collect risk factors, colitis treatment, endoscopic features, and clinical outcomes. Continuous variables were compared between the three groups using Wilcoxon rank-sum test. Categorical variables were compared using chi-square test. Results: Total of 65 patients with MC were included; 15 patients had cancer and received ICPI, 39 patients had cancer without exposure to ICPI, and 11 had no cancer diagnosis. Most were Caucasian (88%), female (63%) with mean age of 62 years. Among the risk factors, proton pump inhibitor was more frequently used in the ICPI-induced MC cohort (P = 0.040; Table 1). Mucosal abnormality (i.e. erythema, edema and altered vascularity) was the most common endoscopic feature in patients with ICPI-induced MC compared to normal findings in the non-ICPI-induced MC groups (P = 0.106; Table 2). Budesonide was used less frequently for patients with ICPI-induced MC than other groups (P = 0.008). Instead, patients with ICPI-induced MC required treatment with oral and intravenous steroids, and nonsteroidal immunosuppressive agents more than other groups (P < 0.001 for all). Higher number of hospitalizations was required for patients with ICPI-induced MC compared to those without ICPI exposure (P < 0.001). The recurrence rate for the three entities was comparable (P = 0.502). In the ICPIinduced MC group, 13 patients had histological features of lymphocytic colitis whereas 2 had features of collagenous colitis (Table 3). Conclusion: This study suggests that despite the similarities in histological features between MC with and without ICPI exposure, MC in patients receiving ICPI treatment was more frequently associated with abnormal mucosal injury and aggressive disease course that requires potent immunosuppressive therapy and hospitalization.123_A Figure 1 No Caption available.123_B Figure 2 No Caption available.123_C Figure 3 No Caption available.