Unrelated Cord Blood Following Haploidentical HSCT with Post-Transplant Cyclophosphamide Improves Results of Alternative Donor Transplant in Thalassemia Major
Authors: Li Chunfu , He Yuelin , Liao Jianyun , Xu Wenfeng , Pei Fuyu , Ren Yuqiong , Tan Wanxia 
Published: October 2019

Abstract
Background:
Hematopoietic stem cell transplantation (HSCT) is cure for thalassemia major (TM). However, a suitable donor (HLA matched sibling and unrelated donor) for HSCT is less than 50%. Alternative donors were recently used in TM HSCT. Some study have found that thalassemia-free survival (TFS) was approximately 70% in haploidentical HSCT (h-HSCT) or unrelated cord blood (UCB) transplant for TM patients. So, it is necessary to find out a better h-HSCT for TM patients. In our early practice in leukemic HSCT we found that outcomes were improved by adding UCB to post-transplant cyclophosphamide (PT/Cy) h-HSCT. The latter associated with high mortality related transplant (32%). Henceforth, we used this termed haplocord transplant in TM.
Aim:
To develop a high TFS h-HSCT protocol for TM patients.
Patients and methods
First 10 patients with median age 8 (5-17) old years received NF-13-PT/Cy-TM protocol (fig. 1), in which, UCB was added on day 6 after PT/CY h-HSCT. Following 9 patients with age 9 (4-15) old years received NF-14-PT/Cy-TM protocol (fig. 2), in which three doses Thymoglobuline were added to NF-13-PT/Cy-TM protocol. Cyclophosphamide on day 3 and day 4 after transplant were both GVHD prophylaxis for h-HSCT and conditioning for UCB transplant. The HLA (at HLA-A, -B, -C and ¨CDRB1) for the pair of recipient and donor was 2-loci and more mismatched in h-HSCT and 2-loci and less mismatched in UCB.
Results
The results of haplocord transplants for all patients were showed in table 1. For first 10 patients, final cord blood engrafted in 4 patients; final haploidentical donor engrafted in 3 patients, 2 patients had a primary rejection. One had a secondary rejection and gave up therapy and died of infection. One patient died of grade IV acute GVHD. TFS is 6/10. For second group patients, final cord blood engrafted in 4 patients; final haploidentical donor engrafted in 3 patients, mixed donor engrafted in 2. No patient rejected his graft; All 9 patients live with transfusion independence.
Summary
Our data showed that UCB followed PT/Cy h-HSCT using NF-14-PT/Cy-TM protocol improved the results of alternative donor transplant in thalassemia major.
Registered in Clinical Trials: NCT02126046,
Table 1. Case Gender/Age(Y) TransplantTime Months After Transplantation Last engraftment(Month) Current Status 1 2 3 4 5 6 1 M/8 2012.09 Mix Mix Mix Mix Mix Mix CB (15) Alive 2 M/5 2012.11 CB CB CB CB CB CB CB Alive 3 M/6 2013.01 / / / / / / / Reject 4 M/17 2013.03 PB PB PB PB PB PB PB Alive 5 M/11 2013.11 Mix Mix Mix Mix Mix Mix Mix (14) Dead 6 M/6 2013.12 Mix Mix Mix CB CB CB CB Alive 7 F/17 2014.03 Mix Mix Mix CB CB CB CB Alive 8 F/7 2014.05 PB PB PB PB PB PB PB Alive 9 F/14 2014.05 PB PB PB Dead / / PB (3) Dead 10 M/8 2014.05 / / / / / / / Reject 11 M/9 2014.08 Mix PB PB PB PB PB PB Alive 12 M/9 2014.08 Mix PB PB Mix Mix Mix PB (7) Alive 13 M/9 2014.10 Mix Mix Mix Mix Mix Mix Mix (9) Alive 14 M/4 2014.10 Mix Mix CB CB CB CB CB Alive 15 F/7 2014.11 PB PB PB PB PB PB PB Alive 16 M/8 2014.12 Mix Mix Mix Mix Mix CB CB Alive 17 M/15 2014.12 Mix Mix Mix CB CB CB CB Alive 18 M/14 2015.03 PB PB PB PB PB Alive 19 F/14 2015.06 Mix CB CB Alive PB: Haploidetical PBSC; CB: cord blood
Figure 1. Figure 1. Figure 2. Figure 2.

Disclosures
No relevant conflicts of interest to declare.