Enfortumab Vedotin Drug Eruption: Cutaneous Adverse Events and Histopathologic Findings

Enfortumab is a monoclonal antibody directed against nectin-4 and, when combined with vedotin, is an antibody-drug conjugate approved for the treatment of locally advanced or metastatic urothelial cancers. A 75-year-old woman with stage IV papillary urothelial carcinoma of the bladder who completed cycle 2 of enfortumab vedotin (EV) infusions presented to our dermatology department for new-onset symmetric and painful dusky erythematous patches on the extremities and trunk without mucosal involvement. Two biopsies were obtained, which revealed an interface dermatitis with notable ring mitoses within the basal and suprabasal layers of the epidermis without epidermal necrosis. The patient was diagnosed with toxic erythema of chemotherapy and improved with application of triamcinolone 0.1% ointment twice daily without discontinuation of her EV infusions. Although a targeted therapy, EV commonly exhibits cutaneous side effects due to the expression of nectin-4 in the skin. Most cutaneous side effects are mild and can be managed symptomatically. However, severe drug-induced eruptions, such as toxic epidermal necrolysis, have been described. The histologic findings of EV associated skin eruptions can aid in correctly identifying the culprit drug and assist in management. This case provides insights for dermatologists by highlighting the common cutaneous side effects of EV and the associated histologic findings as this targeted therapy becomes increasingly utilized in the treatment of refractory neoplasms.