Fecal microbiota transplantation (FMT) for immune checkpoint inhibitor induced–colitis (IMC) refractory to immunosuppressive therapy.

3067 Background: ICIs are efficacious treatment for several advanced malignancies. IMC can limit their use, and can be refractory to medical treatment (immunosuppression) with significant morbidity. Gut microbiome alteration affects IMC development. We sought FMT as a novel therapy for IMC refractory to immunosuppressive therapy. Methods: 15 patients who received FMT for IMC after failure of immunosuppressive therapy were included (6/2017-1/2020). FMT was performed via colonoscopy with healthy donor’s stool. Results: Median age was 55 years with 67% males. 5 patients received PD(L)-1, one CTLA-4 and 9 on combination. Majority had genitourinary cancers followed by melanoma. Median time from ICI to IMC was 75 days. 14 patients had grade 3-4 diarrhea and 9 had grade 3-4 colitis. Endoscopy showed mucosal inflammation in 12 patients and normal mucosa in 3 patients. IMC was refractory to 2-3 doses of infliximab or vedolizumab after corticosteroids prior to FMT. Median time from IMC onset to FMT was 75 days. 13 patients received one . 11 patients achieved clinical response within 10 days of FMT (7-14). Symptom remission was maintained for a median follow-up of 13 months. 6 patients resumed non ICI cancer treatments after FMT. 4 patients had persistent symptoms; 2 continued on vedolizumab, 1 had total colectomy, and 1 transferred to hospice. 4-8 weeks after FMT, endoscopic remission was achieved in 64% of the 11 patients who responded to FMT. No adverse events were reported. Conclusions: FMT treatment was successful in 73% of patients with for IMC refractory to immunosuppressive therapy. Controlled clinical trials are warranted to confirm our conclusion. [Table: see text]