Unrelated Umbilical Cord Blood Transplant for Children with Leukemia: Single or Double Unit Transplant

• Published in: Blood 2008-11, Vol.112 (11), p.4422-4422
• Main Authors: Li, Chi Kong, Lee, Vincent, Cheng, Frankie WT, Li, Karen, Tsang, Kent KS, Leung, Wing Kwan, Shing, Matthew MK
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V112.11.4422.4422

Unrelated umbilical cord blood transplant (UCBT) was performed in 24 children (16 M, 8 F) with leukemia in a single institution from June 1998 to May 2008. The leukemia types were Acute Lymphoblastic Leukemia (ALL, n=13), Acute Myeloid Leukemia (AML, n=9) and Juvenile Myelomonocytic Leukemia (JMML, n=2). The disease status was CR2 in 13, CR3/4 in 3, refractory or relapse in 8. Fifteen patients received single unit (SU) and 9 patients received double unit (DU) UCBT. The mean age and body weight were 5.7 ± 3.7 year and 19.5 ± 7.9 kg for SU, 7.7 ± 4.0 year and 24.6 ± 9.9 kg for DU, respectively. The sources of cord blood units were from local public CB bank (n=20) and 4 overseas public CB banks (n=4). The cord blood units were not more than 2 HLA antigen mismatches from the patients, and the DU cord blood were also not more than 2 antigen mismatches between each other. The minimal requirement was nucleated cell (NC) dose > 2.5×107/kg for SU, and > 3.7 ×107/kg for DU. The conditioning was TBI based for ALL and busulphan-based for myeloid leukemia. ATG was routinely included except in 5 patients. The engraftment rate was 70.8% for the whole group, and 66.7% and 77.8% for SU and DU, respectively. All the 4 overseas UCBT failed to engraft and the engraftment rate for local CB bank units was 85%. The 2 JMML had failed engraftment, one received SU and 1 DU. There was no significant difference in the transplanted cell dose for SU and DU (combined dose), NC 6.2±3.8×107/kg vs 8.2±3.5×107/kg, CD34 cell 5.0±7.2 ×105/kg vs 3.8±1.3×105/kg, respectively. However patients who had successful engraftment received higher cell dose, NC 7.9±3.9×107/kg vs 4.5±1.8×107/kg (p=0.042), CD34 cell 5.4±6.3 ×105/kg vs 2.2±1.6×105/kg (p=0.073), respectively. All the 9 DU UCBT showed signs of engraftment with donor DNA detected, but two did not achieve neutrophil engraftment and subsequently failed engraftment. On the first chimerism study on Day 7–10, 3 had mixed chimerism (MC, 50–60% vs 40–50%) and 2 became single donor complete chimerism (CC) in the second week study, one had persistent MC up to 1 month but required second transplant for failed neutrophil engraftment. Six patients had CC with single CB unit since the week 1 and were maintained in 5, and another one had failed neutrophil engraftment. Finally 7 DU UCBT had sustained CC with single donor unit, however the finally successfully engrafted unit had lower CD34 cell dose as compared to the non-engrafted unit (1.5±0.5×105/kg vs 2.