Rituximab (RTX) is an antibody against the cell surface CD20 antigen expressed on B cells. It has been reported to successfully treat autoimmune bullous disease, and it was approved by Ministry of Health, Labour and Welfare for refractory pemphigus vulgaris and pemphigus foliaceus in December 2021. Prior to its approval, we employed RTX to treat 4 cases of autoimmune bullous diseases refractory to existing treatments. Those included two cases of pemphigus vulgaris, one case of pemphigus foliaceus, and one case of laminin gamma 1 bullous pemphigoid. All four cases clinically improved after RTX treatment, but two cases relapsed. No serious adverse events were observed. We report those four cases and discuss the therapeutic effects of RTX.

Enfortumab vedotin (EV) is a monoclonal antibody-drug conjugate targeting nectin-4 that is approved for treating urothelial carcinoma. Half of patients treated with EV present with adverse cutaneous reactions such as erythematous rash, blisters, and severe drug eruptions, including Stevens-Johnson syndrome and toxic epidermal necrolysis. A 54-year-old man treated with EV for metastatic urothelial carcinoma developed pruritic erythematous plaques bilaterally on his abdomen, thighs, and left lower limb two days after his first dose. Histopathologically, scattered areas of keratinocyte necrosis and superficial perivascular infiltration of lymphocytes and eosinophils were observed. Based on the clinical and pathological findings, we diagnosed cutaneous reactions induced by EV. Because EV-induced cutaneous reactions can appear as early as soon after the initial administration and can be severe, dermatologists should be involved early to diagnose any eruption.