To investigate colitis in multiple sclerosis (MS) patients treated with B-cell depleting therapies.

Because of their high efficacy, overall safety and convenience of dosing, B-cell depleting agents are increasingly utilized for treatment of MS. While those medications carry the potential risks of common infections and effects on vaccinations, other, more rare complications may be underrecognized. Case reports indicate the possibility of colitis being a potential risk.

We queried our electronic medical records for patients who had both diagnoses of MS and colitis. We selected cases of MS patients who treated with rituximab and/or ocrelizumab subsequently developed gastrointestinal symptoms consistent with colitis. We recorded their demographics, clinical and treatment histories, colitis workup and etiology (tissue biopsies when available), and neurological disability measures.  Patients who were ultimately diagnosed with IBS or colonic dysmotility were excluded.

25 patients met our inclusion criteria. Mean age, EDSS, and disease duration at the time of GI symptom onset was 53, 3.4, and 18 years, respectively. Women represented 92% of the cohort. Colitis etiologies differed: 10 patients (40%) suffered from biopsy-proven microscopic colitis (50% collagenous; 30% lymphocytic; 20% not specified), 10 patients (40%) were diagnosed with monophasic or recurrent closteridium difficile colitis, 1 (4%) with inflammatory bowel disease, 1 with drug-induced colitis, and 5 with a suspected or unspecified colitis. We observed that gastrointestinal symptoms manifested roughly 46 months after B-cell therapy initiation. All infectious cases resolved with specific treatment but cases of colitis did not necessarily remit, with some requiring long-term management. The analysis of histological tissue biopsy results is in progress.

The occurrence of colitis in MS patients is an overall rare complication of the B-cell depleting therapies but is likely under-recognized and underreported. We describe a cohort of patients with significant female predominance, their clinical diagnoses and outcomes, and discuss an approach to management.