Promising results of an anti-CCR4 antibody, KW-0761, for relapsed Adult T-Cell Leukemia-Lymphoma (ATL)

Background ATL is an aggressive T-cell malignancy caused by the virus HTLV-1 with a very poor outcome. ATL, and is characterized by its cell surface expression of CC chemokine receptor 4 (CCR4), to which KW-0761, a defucosylated, humanized antibody with enhanced antibodydependent cellular cytotoxicity (ADCC), binds. In a phase I study of KW-0761 in 13 patients (pts) with CCR4-positive relapsed ATL, encouraging efficacy of KW-0761 was observed (ORR of 31%; 2CRs and 2PRs, ref. 3). Here, we report the result of a pivotal phase II study of KW-0761 in pts with CCR4-positive relapsed ATL.