EBMT Guidelines on Defibrotide for Preventing SOS/VOD in High-Risk Pediatric Patients

Overview

Sinusoidal obstruction syndrome (SOS/VOD) is a severe early complication post-hematopoietic stem cell transplantation in children, with incidences historically exceeding 15-20%. The European Society for Blood and Marrow Transplantation (EBMT) has issued pediatric-specific diagnostic criteria and recommends defibrotide prophylaxis to reduce morbidity and mortality in high-risk pediatric patients.

Background

SOS/VOD is characterized by hepatic sinusoidal and venular injury leading to liver failure and multi-organ dysfunction. Pediatric patients exhibit higher incidence rates and unique clinical presentations, including a significant proportion with anicteric SOS/VOD, complicating diagnosis. Traditional diagnostic criteria relying on hyperbilirubinemia may miss early or anicteric cases, prompting the development of the pEBMT criteria incorporating transfusion-refractory thrombocytopenia (tRT) as an early marker. Defibrotide, targeting endothelial injury, has emerged as a promising prophylactic and therapeutic agent.

Data Highlights

Key Findings

• Children have a substantially higher incidence of SOS/VOD compared to adults, with rates historically reaching up to 60%.
• Anicteric SOS/VOD, lacking hyperbilirubinemia, occurs in up to 30% of cases, challenging traditional diagnostic criteria.
• The pEBMT diagnostic criteria incorporate transfusion-refractory thrombocytopenia (tRT) as an early and sensitive marker for pediatric SOS/VOD.
• Defibrotide prophylaxis significantly reduces the risk of SOS/VOD, with a risk ratio of approximately 0.30 in meta-analyses.
• Early diagnosis and intervention, prior to the onset of hyperbilirubinemia, improve outcomes and reduce mortality in pediatric patients.
• Diagnostic criteria requiring hyperbilirubinemia (Baltimore criteria) underestimate SOS/VOD incidence and delay treatment initiation.

Clinical Implications

Clinicians should apply the pEBMT criteria for early detection of SOS/VOD in pediatric patients, emphasizing transfusion-refractory thrombocytopenia as a key early sign. Prophylactic use of defibrotide in high-risk children is recommended to prevent SOS/VOD and improve survival outcomes. Awareness of anicteric presentations is critical to avoid delayed diagnosis and treatment.

Conclusion

The EBMT guidelines underscore the importance of pediatric-specific diagnostic criteria and the prophylactic use of defibrotide to mitigate the high burden of SOS/VOD in children undergoing hematopoietic stem cell transplantation. Early recognition and intervention remain pivotal to improving prognosis.

References

1. Corbacioglu et al. BMT 2018 -- Pediatric SOS/VOD Diagnostic Criteria
2. McDonald et al. 1993 -- Transfusion-Refractory Thrombocytopenia in SOS/VOD
3. T-IND Trial NCT00628498 -- Incidence and Outcomes of SOS/VOD
4. EBMT Guidelines 2018 -- Defibrotide Use in Pediatric SOS/VOD