Early Initiation of Defibrotide is Associated With Better Survival in Sinusoidal Obstruction Syndrome/Veno-Occlusive Disease in Adults: Experience From Two Canadian Centers.

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) after allogeneic hematopoietic transplant (HCT) is associated with high mortality. We evaluated a cohort from 2 Canadian transplant centers to identify predictors of death among patients treated with defibrotide. We conducted a retrospective study of 40 patients with SOS/VOD treated with defibrotide at 2 Canadian centers between January 2016 and June 2023. The primary outcome was overall survival at D+100. Cox proportional hazards regression was used to explore factors associated with mortality. Median patient age was 55 years (interquartile range (IQR): 48 to 63), and 55% were male. Myeloablative conditioning was used in 52.5% of patients, most commonly with busulfan. The median time from HCT to SOS/VOD diagnosis was 13 days (IQR: 11 to 16), and 90% of patients had advanced disease at presentation. Overall survival at D+100 was 70%, with 75% for severe and 58% for very severe cases. Patients who received defibrotide within 2 days of diagnosis had higher D+100 survival (77% versus 20%, P = .003). In Cox regression analysis, initiation of defibrotide more than 2 days after diagnosis (hazards ratio (HR) 6.65; 95% confidence interval (CI): 1.9 to 22.6; P = .002), requirement for dialysis (HR 4.49; 95% CI: 1.9 to 10.7; P = .006), and bilirubin ≥80 μmol/L (HR: 2.89; 95% CI: 1.1 to 7.7; P = .03), were associated with increased mortality, whereas disease severity and age at HCT were not associated with survival. In this cohort from 2 Canadian centers, early initiation of defibrotide therapy for SOS/VOD (<2 days from diagnosis) was associated with improved survival, while the need for dialysis was associated with poorer outcomes. Given the small sample size, these findings should be interpreted cautiously and require validation in larger studies.