Improved survival with model-based dosing of antithymocyte globulin in pediatric hematopoietic cell transplantation

Rick Admiraal*, Stefan Nierkens, Marc B. Bierings, Mirjam E. Belderbos, Alwin D. Huitema, Robbert G.M. Bredius, Yilin Jiang, Kevin J. Curran, Andromachi Scaradavou, Maria I. Cancio, Elizabeth Klein, Wouter J. Kollen, Dorine Bresters, Friso G.J. Calkoen, A. Birgitta Versluijs, C. Michel Zwaan, Jaap Jan Boelens, Caroline A. Lindemans

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Antithymocyte globulin (ATG) is used in pediatric allogeneic hematopoietic cell transplantation (HCT) to prevent graft-versus-host disease (GVHD) and graft failure (GF). Poor T-cell recovery, associated with increased mortality, is the main toxicity of ATG. Model-based precision dosing of ATG (MBD-ATG) minimizes toxicity while maintaining efficacy. We report updated results of the single-arm phase 2 PARACHUTE trial investigating MBD-ATG, combined with real-world experience using identical MBD-ATG. Consecutive patients receiving a first T-cell-replete HCT for any indication were evaluated. Results were compared with historical patients receiving conventional fixed ATG dosing (FIX-ATG). Primary outcome was overall survival (OS). The MBD-ATG group consisted of 214 patients (58 trial patients; 156 real-world patients); 100 patients received FIX-ATG. MBD-ATG led to superior OS compared with FIX-ATG (hazard ratio [HR] for death, 0.56; 95% confidence interval [CI], 0.34-0.93; P = .026), and lower treatment-related mortality (TRM; HR, 0.51; 95% CI, 0.29-0.92; P = .025). Successful T-cell reconstitution (>0.05 × 109/L CD4+ T cells twice within 100 after HCT) was improved in MBD-ATG vs FIX-ATG (87% ± 2% vs 47% ± 5%; P < .0001). The improved T-cell reconstitution led to lower TRM (HR, 0.19; 95% CI, 0.09-0.36; P < .0001). Incidence of grade 2-4 acute GVHD was comparable, whereas chronic GVHD (HR, 0.35; 95% CI, 0.17-0.72; P = .004) and GF (HR, 0.36; 95% CI, 0.13-0.97; P = .044) were both less frequent in MBD-ATG compared with FIX-ATG. MBD-ATG results in improved OS and reduced TRM, while reducing chronic GVHD and GF. This easy-to-implement approach improves outcomes after pediatric HCT, confirmatory studies are needed. The PARACHUTE trial is registered with the Dutch Trial Register as #NL4836.

Original languageEnglish
Pages (from-to)2344-2353
Number of pages10
JournalBlood Advances
Volume9
Issue number9
DOIs
Publication statusPublished - 13 May 2025

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