Conditioning regimens in pediatric myeloid malignancies undergoing allogeneic HSCT: a comparative single-center study

Area of Science:

• Hematology
• Pediatric Oncology
• Transplantation Immunology

Background:

• The optimal conditioning regimen for pediatric myeloid malignancies undergoing allogeneic hematopoietic stem cell transplantation (HSCT) remains debated.
• Comparing myeloablative conditioning (MAC), reduced-toxicity conditioning (RTC), and reduced-intensity conditioning (RIC) is crucial for improving patient outcomes.

Purpose of the Study:

• To compare the efficacy and toxicity of MAC, RTC, and RIC in pediatric patients with myeloid malignancies undergoing HSCT.
• To evaluate graft-versus-host disease (GvHD), relapse rates, survival, and mortality causes across different conditioning regimens.

Main Methods:

• Retrospective analysis of 59 pediatric patients with myeloid malignancies undergoing HSCT.
• Comparison of MAC, RTC, and RIC, with a subgroup analysis of fludarabine- and clofarabine-based RTC regimens.
• Evaluation of primary endpoints including GvHD, relapse, overall survival (OS), disease-free survival (DFS), and mortality, alongside secondary endpoints like complications and engraftment kinetics.

Main Results:

• RTC demonstrated significantly lower transfusion needs, faster platelet engraftment, and shorter hospitalization compared to MAC and RIC.
• While viral reactivations were more frequent in RTC and RIC, RTC showed more effective viral control, including CMV clearance.
• One-year OS and DFS were comparable, but RTC showed a trend towards higher OS; clofarabine-based RTC regimens indicated improved OS and reduced GvHD and relapse-related mortality.

Conclusions:

• Individualized conditioning strategies are recommended for pediatric myeloid malignancies.
• RTC appears to be a balanced approach for selected pediatric patients undergoing HSCT, offering reduced toxicity and potentially improved outcomes.
• Clofarabine-based RTC regimens show promise for enhancing survival and reducing complications in this patient population.