[Allogeneic hematopoietic stem cell treatment after non-myeloablation (minigraft)]

Allogeneic haematopoietic stem cell transplantation is the best treatment option for many patients suffering from severe haematologic diseases. Allogeneic transplantation is generally preceded, by a myeloablative conditioning regimen consisting of high doses of chemo/radiotherapy. The use of those high dose conditionings is restricted to young patients (< 55 years of age) without significant comorbidities. Unfortunately, median patient age at diagnosis of most haematological malignancies ranges from 60 to 70 years. It has been accepted since the late 1970s that the occurrence of acute and/or chronic graft-versus-host disease (a life-threatening complication of allogeneic transplantation consisting of host organ destruction by donor T cells present in the graft) leads to a dramatic decreased risk of relapse thanks to the destruction of host tumour cells by donor T cells (graft-versus-tumour effects). These observations led several groups of investigators to develop non-myeloablative conditionings for allogeneic haematopoietic stem cell transplantation (also termed mini-transplant) based nearly exclusively on graft-versus-tumour effects for tumour eradication. After a brief introduction, this article reviews preliminary results of nonmyeloablative transplantation and then present some perspectives aimed at increasing the efficacy while decreasing the toxicity of this approach.