Evolution of Thalassaemia Management Four Decades in Thalassaemia Care – Our Achievements and Challenges

Transfusion independency achieved by bone marrow transplantation

Bone marrow transplantation (BMT) has become a standard therapeutic modality for a variety of malignant and non-malignant diseases both in adults and in children. It is used to treat children with risk acute leukaemia which has high risk of recurrence or at relapse and is also applicable for patients with transfusion dependent thalassaemia which is a non-malignant disease. Bone marrow is widespread in the inner compartments of the bones and contains numerous haematopoietic stem cells (HSC). These HSC divide, duplicate themselves and some differentiate into different mature blood cells, namely RBC, WBC and platelet forming cells. The principle is to clear patients’ own marrow by a course of intensive chemotherapy and then infuse normal marrow from a healthy donor. The healthy marrow, if successfully implanted to a recipient marrow space, can continue to produce different ideal donors matched sibling who has the same Human Leucocyte Antigen (HLA) pattern as the index patient. The HLA is blood group complex on our normal white blood cell which is analogous to red blood cells but more heterogeneous and to avoid graft rejection and to reduce a special complication called graft versus host disease (GvHD). It governs the immune system in tissue acceptance and rejection. Our HLA haplotype is inherited from parents, one set from each. A sib should have 25% chance of fully matching the HLA haplotypes. BMT carries risk

The first successful allogeneic HSCT was done in the USA in 1968. In Hong Kong the first BMT in Hong Kong was first performed in 1990. HLA-matched sibling HSCT for thalassaemia started initially with marrow in 1991, and with cord blood in 1994. Employing conditioning regimens containing anti-thymocyte globulin, HSCT results in transfusion-independence in over 90% of recipients.