Effect of anti‐ CCR 4 monoclonal antibody (mogamulizumab) on adult T ‐cell leukemia–lymphoma: Cutaneous adverse reactions may predict the prognosis

Adult T ‐cell leukemia–lymphoma ( ATL ) is one of the most malignant lymphomas with poor prognosis. ATL cells express CC chemokine receptor 4 ( CCR 4) and mogamulizumab, a monoclonal antibody against CCR 4 that exhibits very strong cytotoxicity for ATL cells via antibody‐dependent cellular cytotoxicity. Although its effect is dramatic in ATL , serious adverse reactions such as S tevens– J ohnson syndrome have been reported. However, these eruptions can appear as therapeutic signs of mogamulizumab. We evaluated the effectiveness of mogamulizumab in five acute‐type ATL patients. Peripheral blood ( PB ) and lymph nodes ( LN ) were affected in three and four patients, respectively. In PB , complete response ( CR ) was obtained in all three patients and partial response ( PR ) was recorded in LN of one patient. In skin lesions, four of five patients manifested CR ; in two, the lesions worsened after the start of mogamulizumab treatment and subsequently improved. In these lesions, CD 4 + 8 − 25 + ATL cells were replaced by CD 3 + 8 + cytotoxic T cells. Cutaneous adverse reactions ( CAR ) developed in two patients with CR ; they did not show a relapse of ATL over the course of 9 months. Our findings suggest that mogamulizumab should be continued and surface marker evaluation should be performed even in patients whose skin lesions show aggravation, and that CAR may be a marker for a favorable prognosis.