Reduced Toxicity Conditioning for Nonmalignant Hematopoietic Cell Transplants

Area of Science:

• Pediatric Hematology
• Immunology
• Transplantation Medicine

Background:

• Allogeneic hematopoietic cell transplantation (HCT) for pediatric nonmalignant disorders faces challenges with drug toxicity and engraftment.
• Optimizing conditioning regimens is crucial for improving outcomes in this patient population.

Purpose of the Study:

• To evaluate the safety and efficacy of a targeted regimen of busulfan, fludarabine, and intravenous (IV) alemtuzumab in children undergoing HCT for nonmalignant disorders.
• To assess engraftment, survival, and graft-versus-host disease (GVHD) incidence with this low-toxicity conditioning regimen.

Main Methods:

• Retrospective analysis of 62 children receiving their first HCT for nonmalignant disorders between 2004 and 2018.
• Conditioning regimen included targeted busulfan, fludarabine, and IV alemtuzumab, with some patients receiving additional immunoablation.
• Data collected on graft failure, chimerism, treatment-related mortality, overall survival, event-free survival, and acute/chronic GVHD.

Main Results:

• Low graft failure rate (8.4%) with high median donor chimerism (96% in whole blood at 1 year).
• 3-year cumulative incidence of treatment-related mortality was 10%, with overall survival at 87% and event-free survival at 80%.
• Low incidence of acute GVHD (7% at 6 months) and chronic GVHD (5% at 3 years).

Conclusions:

• Targeted busulfan, fludarabine, and IV alemtuzumab is a well-tolerated and effective conditioning regimen for pediatric HCT in nonmalignant disorders.
• This regimen facilitates sustained donor engraftment with a low risk of GVHD.
• The findings support this approach as a viable option for improving HCT outcomes in children with these conditions.