Safety of Immune Checkpoint Inhibitors in Patients With Pre-Existing Inflammatory Bowel Disease and Microscopic...

Enterocolitis is among the leading adverse events associated with immune checkpoint inhibitors (ICIs). There are limited retrospective data regarding the safety of ICIs in patients with inflammatory bowel disease (IBD; ulcerative colitis, Crohn's disease) because they have been generally excluded from clinical trials testing ICIs. Furthermore, there are no outcome data available in patients with microscopic colitis, a leading cause of chronic diarrhea. We aimed to study the safety of ICIs in patients with cancer with pre-existing IBD or microscopic colitis.

We retrospectively reviewed the records of patients with cancer treated at our institution who received at least 1 dose of either a programmed cell death-1 (PD-1)/ PD-1 ligand inhibitor, cytotoxic T-lymphocyte-associated antigen 4 inhibitor, or both between 2011 and 2018. We identified patients with pre-existing IBD or microscopic colitis.

Of 548 patients with solid tumor treated with an ICI, we identified 25 with pre-existing colitis (21 IBD; 4 microscopic colitis). An enterocolitis flare occurred in 7 patients (28%): 3 of 4 patients (75%) with microscopic colitis and 4 of 21 (19%) with IBD. All were treated with systemic corticosteroids, 2 required an anti-tumor necrosis factor agent, and one required an anti-integrin agent and colectomy for treatment of refractory colitis. ICI therapy was discontinued in all patients who experienced an enterocolitis flare.

In our cohort, exacerbation of enterocolitis occurred in a notable percentage of patients with IBD and a majority of patients with microscopic colitis, leading to discontinuation of ICIs. Although these data suggest that patients with cancer with pre-existing IBD/microscopic colitis may be treated with ICIs, additional studies are needed to validate our results.