RBC Alloimmunization Impacts Pediatric Sickle Cell Disease Transplant Outcomes and Transfusion Burden: A STAR...

Area of Science:

• Hematology
• Immunology
• Transplantation Medicine

Background:

• Sickle cell disease (SCD) patients frequently require red blood cell (RBC) transfusions.
• RBC alloimmunization is a common complication of transfusion therapy in SCD.
• Alloimmunization may impact outcomes after hematopoietic cell transplantation (HCT).

Purpose of the Study:

• To investigate the association between pre-HCT RBC alloimmunization and post-HCT outcomes in pediatric SCD patients.
• To assess the impact of alloimmunization on transfusion support requirements post-HCT.

Main Methods:

• Retrospective analysis of a multicenter registry (STAR) of 229 pediatric SCD patients undergoing HLA-matched related donor HCT.
• Comparison of outcomes between 40 RBC alloimmunized patients and 189 non-alloimmunized patients.
• Statistical analysis controlling for transfusion burden and conditioning intensity.

Main Results:

• RBC alloimmunized patients had a significantly higher incidence of grade III-IV acute graft-versus-host disease (GVHD) (15% vs. 3.7%, p=0.013).
• Graft failure occurred more frequently in alloimmunized patients (10% vs. 2.6%, p=0.052).
• Five-year severe GVHD-free, rejection-free survival was significantly lower in alloimmunized patients (69% vs. 88%, p=0.004).
• Alloimmunized patients required more post-HCT platelet transfusions but not RBC units.

Conclusions:

• Pre-HCT RBC alloimmunization is associated with increased risk of severe acute GVHD and graft failure in pediatric SCD patients.
• RBC alloimmunization negatively impacts long-term survival outcomes post-HCT.
• Pre-HCT alloimmunization correlates with a higher need for post-HCT platelet transfusions, suggesting underlying immunologic factors.