Relapsed refractory immune checkpoint inhibitor-induced colitis treated with tacrolimus and maintained with vedolizumab.

A 58-year-old man was administered anti-programmed death ligand 1 and cytotoxic T-lymphocyte-associated protein 4 antibodies for primary lung cancer with brain metastasis. Subsequent development of diarrhea was diagnosed as immune-related adverse event (irAE) colitis. Initially, his condition improved with prednisolone (1 mg/kg/day). Therefore, the dose was reduced to 5 mg, and his condition was maintained with 5-aminosalicylic acid. However, diarrhea recurred after re-administration of another immune checkpoint inhibitor. Prednisolone (0.5 mg/kg/day) was ineffective for the first relapse. After two doses of infliximab, irAE colitis improved. One year later, diarrhea recurred after steroid tapering. Treatment comprising prednisolone (1 mg/kg/day), two doses of infliximab, granulocyte-monocyte apheresis, and ustekinumab for the second relapse failed to improve his condition. Tacrolimus was initiated 3 months after the second flare occurred, resulting in rapid symptom resolution. Due to frequently relapsed irAE colitis, vedolizumab was administered as maintenance therapy, allowing steroids and tacrolimus to be discontinued and maintaining remission. Tacrolimus may be effective for relapsed refractory irAE colitis, particularly for cases that cannot be successfully treated with infliximab and other treatments. Vedolizumab can be used as maintenance therapy for frequently relapsing irAE colitis.