Phase II trial of daclizumab in human T-cell lymphotropic virus type-1 (HTLV-1)-associated adult T-cell leukemia/lymphoma (ATL).

8043 Background: ATL is an aggressive malignant lymphoproliferative disorder with a poor prognosis and no standard therapy. ATL can be classified into four subtypes: acute, lymphomatous, chronic and smoldering. Daclizumab is a humanized monoclonal antibody that prevents binding of interleukin-2 by recognizing the α-chain of the interleukin-2 receptor (CD25), which is over-expressed on ATL cells. Preclinical studies in the MET-1 mouse model of ATL showed daclizumab treatment improved survival. A phase I trial demonstrated that up to 8 mg/kg daclizumab was well tolerated with clinical evidence of antitumor activity in ATL. Based on this data, a phase II trial was initiated. Methods: A single institution open-label Phase II trial was conducted, with a primary endpoint of response rate. Eligibility: All ATL subtypes with ≥10% of tumor cells expressing CD25. Patients received intravenous daclizumab 8 mg/kg on days 1 and 15, and then every 3 weeks to complete 6 doses. Responding patients continued to receive da...