A phase II study of the efficacy and toxicity of alemtuzumab for the therapy of human T cell lymphotrophic virus-1 (HTLV-1)-associated adult T-cell leukemia/lymphoma (ATL)

Abstract

2535 Background: HTLV-1-associated ATL is an aggressive lymphoproliferative disorder with limited effective therapy. Alemtuzumab is a humanized monoclonal antibody directed against CD52. High levels of CD52 are expressed on the surface of ATL cells. Preclinical studies in the MET-1 mouse model of ATL showed alemtuzumab to be highly active. Methods: A single institution open-label phase II study examining the response and toxicity of alemtuzumab in patients with ATL. Eligibility criteria: HTLV-1-associated ATL (chronic, acute and lymphoma type), ≥10% CD52+ malignant cells, measurable disease, age ≥18 years, AGC ≥1000/μL, platelets ≥50,000/μL, adequate physiologic status and informed consent. Results: Ten (10) patients, 6 with leukemia, 4 with lymphoma, 8 Afro-Caribbean, 1 African-American and 1 Japanese, 7 women, 3 men, median age 49 years (range, 36–62), all having received previous treatments including CHOP (7), other monoclonal antibodies (5), radioimmunotherapy (2), and radiation (1), median WBC 48,500/μL (leukemia Pts.) received alemtuzumab standard induction followed by 30 mg 3 times weekly for a minimum of 4 weeks and maximum of 12 weeks. All patients experienced infusion reactions (grade, 1–3) including hypotension, fever, rigors, chills, pruritus and urticaria; however, no patient required discontinuation of treatment. All patients developed grade 4 lymphopenia, and transient cytomegalovirus (CMV) antigenemia. Four (4) patients with leukemia responded (1 CR, 3 PR). No patient with lymphoma responded. Conclusions: Alemtuzumab has antitumor activity in HTLV-1-associated adult T cell leukemia and is well tolerated. Lymphomatous ATL appears unresponsive to alemtuzumab. The reason for this is unknown; however, antibody levels achieved in lymph nodes may be suboptimal. Accrual continues. No significant financial relationships to disclose.