Abstract
BACKGROUND: Various molecular-targeted therapeutic agents that inhibit cytokines and immune checkpoints are used in clinical practice. Some of these biologics that control immunity, such as anti-interleukin-17, anti-programmed cell death protein-1, and anti-cytotoxic T-lymphocyte-associated protein antibodies, affect intestinal immune homeostasis and cause intestinal inflammation. Development of enteritis due to dupilumab (an anti-IL-4Ralpha monoclonal antibody) therapy is not yet reported in the literature. CASE PRESENTATION: A 17-year-old man was administered an injection of dupilumab and continued to receive it for refractory atopic dermatitis. After 3 months of initiating dupilumab therapy, he developed intermittent abdominal pain, tenesmus, and had diarrhea. Colonoscopy examination showed decreased vascularity, mild friability, and erythema in the cecum, part of the ascending colon, sigmoid colon, and rectum without any pathogenic bacteria. Histological examination revealed moderate mixed inflammatory cell infiltration, cryptitis, destruction of the crypt, decreased goblet cells, mucosal erosions, and edema. He was diagnosed with UC and was prescribed oral mesalazine (4800 mg/day) treatment. Within a month of the treatment, his diarrhea improved and the frequency of defecation decreased. CONCLUSIONS: This is a first report that dupilumab mimicked ulcerative colitis. Careful monitoring for adverse effects with the onset of an intestinal inflammation will be recommended after dupilumab administration.