Comparable Outcomes of Myeloablative Conditioning Regimen without ATG in CBT for Pediatric Patients with Hematological Malignancies with a Weight of More Than 30 Kilograms Vs. Less Than 30 Kilograms

Purpose

Cord blood transplantation (CBT) is an effective option for the treatment of pediatric patients with acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), and myelodysplastic syndrome (MDS), but children with heavier weight (weighing more than 30kg) always have inferior outcomes than children with lighter weight. This article aims to identify the outcomes of myeloablative conditioning regimen (MAC) without antithymocyte globulin (ATG) in CBT for pediatric patients with different weight.

Methods

We conducted a retrospective analysis including 142 pediatric patients weighing less than 30kg and 130 pediatric patients weighing more than 30kg from May 2008 to September 2017 in our center. All the children were given a combination of cyclosporine (CsA) and mycophenolate mofetil (MMF) without ATG for graft-vs.-host disease (GVHD) prophylaxis. Most of the lighter children and two third of the heavier children were given busulfan(Bu) based MAC while another one third of the heavier children were given total body irradiation (TBI) based MAC.

Results

Children with different weight had no difference in gender, disease status, disease risk, and blood type. However, heavier children were older and had more loci of human leukocyte antigen(HLA) mismatch (P=0.000 and P=0.016). More children weighing more than 30kg suffered ALL than children weighing less than 30kg (P<0.05). The cumulative neutrophil engraftment rate by 42 days and the platelet engraftment rate by 120 days were almost the same in heavier children group and lighter children group (97.7% vs. 94.4% and 86.2% vs. 86.6%, p=0.284 and p=0.313, respectively). Non-relapse mortality (NRM) and relapse rate were also similar in these two groups (16.3% vs. 12.3% and 22.0% vs. 21.9%, p=0.345 and p=0.923, respectively). While the incidence of chronic GVHD (cGVHD) was higher in heavier children group (17.9% vs. 9.4%, P<0.05), but not grade II to IV acute GVHD (aGVHD) nor grade III to IV aGVHD. Three years of overall survival (OS), disease-free survival (DFS) and GVHD-free/relapse-free survival (GRFS) showed no significant difference in these two groups.

Conclusions

This study is the first to demonstrate the similar curative effect of myeloablative conditioning regimen without antithymocyte globulin in CBT for pediatric patients with different weight. A large-scale prospective study is needed.