Treatment of hematological malignancies relapsing after allogeneic bone marrow transplantation

The rate of relapse after allogeneic bone marrow transplantation (BMT) varies between 15 and 60%. New therapeutic strategies are required urgently as no significant results have been obtained with standard chemotherapy. The best results of second allogeneic BMT have been obtained when the interval between the first and the second transplant was more than 6 to 20 months, depending on the study. Veno-occlusive disease was an important cause of non-leukemic death (13-65%). As the toxicity of second BMT is very high, other treatments have been considered: complete remissions were reported after sudden discontinuation of the immunosuppressive therapy. Interferon-alpha has been used for chronic myeloid leukemia patients and may achieve hematological and cytogenetic complete remission. More recently, donor leucocytes transfusions have been proposed and at least in some cases, have led to molecular complete remission (polymerase chain reaction with double amplification) in chronic myeloid leukemia patients. However, non predictable marrow aplasias and graft-versus-host reactions hamper the efficacy of this strategy. Finally, hemopoietic growth factors used to promote donor cell growth produce interesting results which deserve further studies.