Toxic epidermal necrolysis after the administration of enfortumab vedotin for urinary bladder urothelial carcinoma

INTRODUCTION: Enfortumab vedotin is a novel drug for locally advanced or metastatic urothelial carcinoma, but it is associated with a high incidence of skin reactions (up to 47.0%). CASE PRESENTATION: A 71‐year‐old male was administered enfortumab vedotin for bladder cancer associated with lymph node metastases. Slight erythema of the upper limbs appeared on Day 5. Erythema gradually worsened. On Day 8, second administration was performed. On Day 12, based on the extents of blisters, erosion, and epidermolysis, a diagnosis of toxic epidermal necrolysis was made. The patient died of multiple organ failure on Day 18. CONCLUSION: As serious cutaneous toxicity may appear early after the start of administration, it is important to consider the timing of the second administration of the initial course carefully. In cases of skin reaction, reduction or discontinuation should be considered.