Allogeneic haematopoietic stem cell transplantation (HSCT) is a potentially curative therapy for patients with both haematological and some non-haematological disorders. However, one of the major limiting factors for transplantation is the inability to identify a suitable HLA-matched donor. Development of an cost-effective and clinically efficacious alternative to HLA-identical sibling or unrelated donor transplantation would significantly expand the availability of allogeneic HSCT to patients in Singapore. Preliminary results indicate that the use of high dose post-transplant cyclophosphamide (Cy) for graft versus host disease (GVHD) prophylaxis in haplo-identical allogeneic HSCT is associated a low incidence of GVHD and low treatment related toxicity. We propose a phase II clinical trial to assess the efficacy of a haplo-identical allogeneic transplantation protocol using high dose post-transplant Cy for the treatment of patients with haematological disorders. A non-myeloablative protocol (Fludarabine-low dose cyclophosphamide-TBI) will be used for patients with bone marrow failure syndromes and indolent lymphoid disease. In view of the higher relapse risk of patients with myeloid malignancies, these patients will be treated with a reduced intensity conditioning regimen (Fludarabine-Busulphan). The primary end-point of the study will be overall survival at one year. Economic cost of the haplo-identical transplantation, as well as treatment timelines will be recorded and compared will other forms of unrelated donor allogeneic transplantation (umbilical cord blood transplantation and unrelated HLA-matched adult donor). Immunological reconstitution of patients following haplo-transplantation will be analysed and data will be utilized to guide future immunotherapy strategies post-transplantation.
One year survival after non-myeloablative haploidentical stem cell transplantation is not inferior to that observed after non-myeloablative volunteer unrelated donor or unrelated cord blood haematopoietic stem cell transplantation.