Allogeneic hematopoietic stem cell transplantation for adult T-cell leukemia-lymphoma

Long survival is obtained in 30-40% of adult T-cell leukemia-lymphoma (ATL) patients with allogeneic hematopoietic stem cell transplantation (allo-HSCT) using HLA-matched related or unrelated donors. Myeloablative conditioning is generally used for patients 55 years of age and older, while reduced intensity conditioning is given to those between 50-70 years of age. Overall survival periods do not differ significantly between these two conditioning methods. Survival rates with cord blood transplantation are not inferior to those obtained with bone marrow transplantation or peripheral blood stem cell transplantation. Prognostic factors such as age, gender, performance status, disease status at transplantation and serum soluble interleukin-2 receptor are known to have an impact in ATL patients receiving allo-HSCT. Mild acute graft-versus host disease is associated with good overall survival. Cessation of immunosuppressants or donor lymphocyte infusion often induces another remission in relapsed ATL patients after allo-HSCT. This phenomenon is regarded as a graft-versus-ATL effect mediated by activated cytotoxic T-cells. Donor cell derived-ATL has, on rare occasion, been reported in patients receiving allo-HSCT from HTLV-1 carrier donors. Special attention should be paid to the use of mogamulizumab before allo-HSCT, since this agent kills normal regulatory T-cells as well as ATL cells.