S4074 Chimeric Antigen Receptor T-Cell Therapy Induced Enterocolitis and Treatment With Vedolizumab

Introduction: Chimeric antigen receptor T cell (CAR-T) therapy has become a transformative treatment for various leukemias and lymphomas. This case report aims to highlight colitis as a rare complication of CAR-T therapy. Case Description/Methods: A 61-year-old man with a history of multiple myeloma treated with autologous stem cell transplant and CAR–T. He developed diarrhea over the past 4 months with 10-15 large-volume watery bowel movements daily. He denies gastrointestinal (GI) bleeding, steatorrhea, or tenesmus. He reports that before his CAR-T therapy, he had 1-2 formed bowel movements a day. He denies sick contacts, travel, nonsteroidal anti-inflammatory drugs, dairy, new medications, or association with gluten intake. GI Biofire, C. difficile, Giardia, Cryptosporidium, cytomegalovirus, and HIV were negative. Fecal fat, sodium, chloride, potassium, and elastase were normal. Computed tomography abdomen and pelvis: diffusely and mildly distended small and large bowels without surrounding inflammation. Esophagogastroduodenoscopy showed that esophagus, stomach, and duodenum were normal, and colonoscopy showed normal colonic mucosa. Pathology showed duodenal mucosa with increased intraepithelial apoptotic bodies and reactive epithelial changes. Colonic mucosa with scattered intraepithelial apoptotic bodies. With biopsies concerning for CAR-T related colitis and common etiologies ruled out, 40 mg prednisone was started with no improvement. The patient started vedolizumab with partial clinical improvement after the first infusion. Discussion: CAR-T therapy colitis was first reported in 2021. Due to its novelty, diagnosis and treatment rely on case studies and expert opinion. There are a few rare cases reported thus far. Treatment response has been highly variable across these reports. One patient had spontaneous resolution, while others required biologics. A few patients had refractory disease despite a trial of multiple biologics. There have been reported bowel perforations in association with this disease. This patient had a partial response to initial vedolizumab and continues to have close monitoring. With the rarity of this disease and increasing interest in CAR-T therapy, more reports and awareness are needed to decipher pharmacotherapy. Our patient provides further evidence of the potential efficacy of vedolizumab in glucocorticoid-refractory CAR-T-related diarrhea/colitis.