Biology and treatment of HTLV-1 associated T-cell lymphomas.

Adult T-cell leukemia-lymphoma (ATL) is a distinct peripheral T-lymphocytic malignancy associated with human T-cell lymphotropic virus type I (HTLV-1) endemics in several regions of the world including the south-west Japan. The three major routes of HTLV-1 transmission are mother-to-child infections via breast milk, sexual intercourse, and blood transfusions. A HTLV-1 infection early in life, presumably from breast feeding, is crucial to the development of ATL. The estimated cumulative risk of developing ATL among HTLV-1-positive individuals is about 3% after transmission from the mother. The diversity in clinical features and prognosis of patients with this disease has led to its subtype-classification into acute, lymphoma, chronic, and smoldering types defined by organ involvement, lactate dehydrogenase (LDH) and calcium values. For the acute, lymphoma and unfavorable chronic subtypes (aggressive ATL), and the favorable chronic and smoldering subtypes (indolent ATL), intensive chemotherapy followed by allogeneic stem cell transplantation and watchful waiting until disease progression has been recommended, respectively, in Japan. A retrospective analysis suggested that the combination of interferon alpha and zidovudine was promising for the treatment of ATL, especially for leukemic subtypes. There are several new trials for ATL, including a defucosylated humanized anti-CC chemokine receptor 4 monoclonal antibody, histone deacetylase inhibitors, a purine nucleoside phosphorylase inhibitor, a proteasome inhibitor and lenalidomide.