P1272: DEFIBROTIDE IMPACT ON THE ACUTE GRAFT-VERSUS-HOST DISEASE INCIDENCE IN PEDIATRIC HEMATOPOIETIC STEM CELL TRANSPLANT RECIPIENTS.

Topic: 22. Stem cell transplantation - Clinical Background: Despite advances in acute graft-versus-host disease (aGVHD) prophylaxis, current pharmacological approaches fail to prevent aGVHD. The protective effect of defibrotide on GVHD incidence and GVHD-free survival has been insufficiently studied. Aims: The aim of this study was to assess the impact of defibrotide on the incidence and severity of aGVHD in a population of pediatric patients undergoing an allo-HSCT. Methods: Ninety-one pediatric patients included in this retrospective study were divided into two groups based on defibrotide use. We compared the incidence of aGVHD and chronic GVHD-free survival between the Defibrotide Group and the Control Group. Results: The incidence and severity of aGVHD were significantly lower in patients who received defibrotide prophylactic administration than in the Control Group. This advantage was observed in the liver and intestinal aGVHD. No defibrotide prophylaxis benefit was observed in the prevention of chronic GVHD (Figure 1). Moreover, the Defibrotide Group has recorded no sinusoidal obstruction syndrome (SOS)/veno-occlusive disease. The pro-inflammatory cytokines levels were significantly higher in the Control Group. Summary/Conclusion: Our findings suggest that prophylactic administration of defibrotide significantly reduces the incidence and severity of aGVHD, with a modification of patients’ cytokine pattern, strongly coherent with protective drug action. High costs currently limit the drug’s use. The positive impact on patient outcomes and the reduced long-term burdensome costs of GVHD and SOS should be considered.Keywords: Defibrotide, Acute graft-versus-host disease, Pediatric