Ishida T, et al. – In this study, the prognosis of adult T–cell leukemia–lymphoma (ATL) patients receiving mogamulizumab, a defucosylated anti–CCR4 monoclonal antibody, was ascertained. It was inferred that mogamulizumab monotherapy had the potential to improve progression–free survival (PFS) and overall survival (OS) in some patients with relapsed aggressive ATL. This finding was more evident in those who developed a skin rash as a moderate immune–related adverse event.