BG08 Drug-induced colitis secondary to dupilumab prescribed for pompholyx eczema–bullous pemphigoid overlap: a case report

Abstract Biologic medications are commonplace in a dermatologist’s clinical practice. Dupilumab is a monoclonal antibody that binds to the interleukin (IL)-4a subunit, inhibiting IL-4 and IL-13 cytokine-induced responses. In skin disease, it is currently licensed and widely used for management of atopic dermatitis, but its use in bullous pemphigoid is recognized in the literature, and it is becoming more commonly integrated into practice. This report describes a case of drug-induced colitis secondary to dupilumab when prescribed for pompholyx eczema–bullous pemphigoid overlap. To our knowledge there are two case reports describing development of ulcerative colitis in patients prescribed dupilumab for atopic dermatitis, but no cases of drug-induced colitis. A 68-year-old woman presented to dermatology for management of bullous pemphigoid complicated by pompholyx eczema. She was commenced on dupilumab 600 mg subcutaneously as an initial dose, followed by 300 mg fortnightly. Within a month she had a dramatic improvement in her skin. However, after 3 months, she reported increasing bowel movements, eight to 10 per day. Computed tomography, colonography and sigmoidoscopy were normal at the time and she continued on her dupilumab regimen. Eighteen months after commencing dupilumab, she required acute admission to hospital for management of colitis. A repeat sigmoidoscopy demonstrated acute inflammation in the sigmoid colon to the point of insertion. Macroscopically there were small, deep, punched-out ulcers. Histological findings demonstrated focal active colitis, but features of chronicity were not identified. She was diagnosed with drug-induced colitis secondary to dupilumab. Improvement in bowel symptoms necessitated withdrawal of dupilumab and commencement of infliximab 5 mg kg−1. They have remained well controlled 18 months later. This case report describes a rare occurrence of drug-induced colitis secondary to dupilumab and highlights the need for careful observation for adverse effects and prompt intervention.