[HLA haploidentical peripheral blood stem cells transplantation for β thalassemia major]

To evaluate the feasibility of HLA haploidentical peripheral blood hematopoietic stem cell transplantation (PBSCT) for patients with β thalassemia major.

Sixteen patients with β thalassemia major received HLA haploidentical PBSCT from parents. Two conditioning regimens were used. Regimen A was adopted before December 2007, which consisted of fludarabine (total 150 mg/m²), busulfex (total 520 mg/m²), cyclophosphamide (CTX, total 100 mg/kg), antithymocyte globulin (ATG, total 10 mg/kg) and total body irradiation of 3 Gy. Regimen B was adopted after December 2007, which consisted of fludarabine (total 240 mg/m²), busulfex (total 520 mg/m²), CTX (total 100 mg/kg), and ATG (total 10 mg/kg). Combination of cyclosporin (CsA), methotrexate (MTX) and mycophenolate mofetil (MMF) were used for prophylaxis of graft-versus-host disease (GVHD).

Of 16 patients, 14 (87.5%) had sustained engraftment. The median days of neutrophil exceeding 0.5 × 10⁹/L and platelet exceeding 20 × 10⁹/L were 13 days (range 10 - 17 days) and 15 days (range 14 - 20 days) after PBSCT, respectively. Complete chimerism was achieved in all the 14 patients at one month after PBSCT. One patient lost his graft with autologous reconstitution 52 days after transplantation. Four patients had grade II-IV acute GVHD and one patient had chronic extensive GVHD. In the 49-month median follow-up duration, 13 of 16 patients were alive in disease-free situation.

HLA haploidentical PBSCT, which could provide stable and sustained engraftment for thalassemia major patients with no HLA identical donor, is a promising treatment strategy.