Effect of fecal transplantation on patients' reported outcome after immune checkpoint inhibitor colitis

2645 Background: The use of fecal microbiota transplantation (FMT) has traditionally been reserved for the treatment of recurrent Clostridioides difficile infections (CDI). As the gut microbiome has been increasingly acknowledged to play a role in a variety of bodily processes, FMT has seen its application extended to other gastrointestinal disorders. Immune-mediated colitis (IMC) is a similar entity to inflammatory bowel disease and arises as a side effect of immune checkpoint inhibitor therapy to stimulate the immune response. Treatment of IMC is mostly limited to immunosuppressants e.g. corticosteroids, infliximab, and vedolizumab. Cases refractory to such medications pose a significant challenge. FMT has been shown to be a successful treatment in refractory IMC in small case series, further large studies are needed to determine its efficacy. Methods: We measured the efficacy of FMT for refractory IMC among 47 patients via chart review and clinical assessment and patients’ reported outcome (PRO) via established MD Anderson Symptom Inventory (MDASI). Among them, 9 patients had concurrent CDI as well at the time of diagnosis. Results: Forty-seven patients were included in our study. Most patients had a peak diarrhea grade ≥ 3 (93.6%) and colitis grade ≥ 2 (91.5%). Ulcerous (23, 49.0%) and non-ulcerous (12, 25.5%) inflammation were the predominant endoscopic findings. 45 (95.7%) patients received corticosteroids, and 43 patients (91.5%) received add-on infliximab or vedolizumab. IMC symptom response was 85.1% after FMT with median time to response of 4.5 days. The transient complications rate is 34.0% at 7 days and 17.0% at 30 days. Response rate among the 38 patients without concurrent CDI was 86.8%. Forty-one (87.2%) patients demonstrated clinical remission by the end of the study period. On the PRO analysis, we observed a favorable trend of significant patient-reported symptom reduction on diarrhea during 12 weeks after FMT, along with improved daily physical functioning on working. Conclusions: FMT may serve as a potential treatment option in IMC refractory to standard treatment to avoid long-term steroid dependency and immunosuppression. It is effective to maintain IMC remission with a low complication rate. The role of the gut microbiome in cancer and the implications for FMT remain uncertain and need further elucidation. Clinical trial information: NCT03819296 . [Table: see text]