Sustained hematologic and central nervous system remission with single-agent denileukin diftitox in refractory adult T-cell leukemia/lymphoma.

Human T-lymphotrophic virus-1-associated adult T-cell leukemia/lymphoma (ATLL) is a rare and often fatal disease. Initial treatment often includes zidovudine/interferon (IFN)-based therapy, although disease remission is typically not complete or durable. This study reports on a 55-year-old man with relapsed/refractory leukemic-phase ATLL including significant central nervous system (CNS) disease with resistance to previous zidovudine/IFN and arsenic trioxide/IFN treatment. The patient experienced a rapid hematologic and CNS clinical response with single-agent denileukin diftitox therapy (18 microg/kg per day for 5 days). He tolerated 8 cycles of denileukin diftitox therapy well and experienced a sustained complete hematologic and CNS remission. The patient subsequently underwent matched sibling reduced-intensity allogeneic transplantation and remains disease free. Further study examining denileukin diftitox in patients with relapsed/refractory ATLL is warranted.