Successful treatment by donor lymphocyte infusion of adult T-cell leukemia/lymphoma relapse following allogeneic hematopoietic stem cell transplantation.

Adult T-cell leukemia/lymphoma (ATLL) is a highly aggressive hematologic neoplasm that has an extremely poor prognosis; however, this has improved following recent progress in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Several clinical studies have shown that discontinuation of immunosuppressant therapy induces durable remission in a significant number of post-transplant relapsed patients, suggesting that ATLL may be susceptible to a graft-versus-leukemia effect. Here, we report two cases with ATLL who received donor lymphocyte infusions (DLIs) for relapse after allo-HSCT; one patient achieved complete remission (CR) after a single DLI, and the other suffered repeated relapses and was treated with chemotherapy and radiotherapy combined with a total of five rounds of DLIs. Both patients presented with exacerbation of the graft-versus-host disease after the DLIs, and remained in CR for 9 and 8 years, respectively. These data support the use of DLIs as an effective therapy to induce durable CR in the treatment of relapsed ATLL. In this study, we review previous reports and discuss the role of DLIs in the treatment of post-transplant relapsed ATLL.