CART-induced eosinophilic colitis with good response to corticosteroids and infliximab: a case report.

Chimeric antigen receptor T-cell (CART) therapy is an efficacious immunotherapy with known multi-organ toxicities, including gastrointestinal adverse events (GI-AEs). Eosinophilic colitis (EoC) is the inflammation of the intestine with diffuse eosinophilic infiltration. We present the case of a 66-year-old male who presented with diarrhea and biopsy-proven EoC two months after CART therapy for recurrent multiple myeloma (MM) and achieved a favorable response following corticosteroids and infliximab. A 66-year-old male with a past medical history of MM presented with watery stools 5-6 times per day. The patient was diagnosed with MM 10 years ago and achieved remission following an autologous stem cell transplant and maintenance chemotherapy. Three years ago, the patient developed recurrent MM, received CART therapy, and achieved cancer remission. Two months following CART therapy, he presented to the local emergency department (ED) for several weeks of diarrhea with a negative infectious workup. This disease course was associated with several ED visits and hospital admissions. He was started on budesonide without a significant response. Subsequent colonoscopy and resultant histology were consistent with EoC. The patient was started on an IV steroid with infliximab and a prednisone taper for refractory EoC. Following his third dose of infliximab and completing his prednisone taper, he reported a return to baseline symptomatically. CART is an immunotherapy associated with GI-AEs and requires corticosteroids or other immunosuppressants in select cases. EoC has been associated with cancer and cancer therapy and may require biological agents. Early recognition and treatment of immunotherapy toxicities are essential for successful management of gastrointestinal adverse events.