Outcomes of Combined Transplants of Cord Blood Plus Peripheral Blood from an HLA Matched Sibling in Thalassemia Patients

Background Cord blood from HLA matched sibling was widely used as stem source in transplants in patients with thalassemia major (TM), but failure of engraftment is frequent.

Aim To improve engraftment of CB transplant in patients TM

Patients and method A combined transplants of CB and peripheral blood (PB) from same HLA matched sibling was conducted (i.e. CB and PB were harvested and infused on day 0) from June, 2010 to February, 2014. Total 24 patients were involved in the study. Donor-recipient pairs were matched at HLA-A, B and DRB1 (antigen level) in 23 but one with HLA mismatched at one loci (DRB1). The conditioning protocol included intravenous busulfan, cyclophosphamide, fludarabine, and thiotepa. Prophylaxis of GVHD included Cyclosporine and short MTX. All donors (newborn) were sent into NICU for monitoring, and then, discharged after 3 days.

Results The median age at transplant was 4 years (range, 1.5-7 years), and the ratio of male-to-female patients was 16:8. The median follow-up time was 17 months (range, 5-49 months). The mean mononuclear cell (MNC) dose of CB was 5.67×10⁷/kg body weight of the recipient (BWR; range, 2.1-8.75×10⁷/kg BWR) while that of PB was 3.21×10⁷/kg BWR (range, 0.47-7.31×10⁷/kg BWR). The mean volume of infused CB was 91ml (range, 31-131ml) while that of PB was35ml (range, 10-71ml). The median ANC engraftment time was 28 days (range, 15-47days), while the median platelet engraftment time was 34.0 days (range, 0-128days). The estimated 4-year overall survival (OS) and TM-free survival (TFS) were both 100%. The cumulative incidences of graft rejection and grades II-IV acut egraft-versus-host disease (aGVHD) were both 0%. All donors are normal as peers with following up to date.

Conclusion These results suggest that patients with TM have excellent outcomes after CB plus PB combined transplant from an HLA matched sibling.