Final Primary Results from the Defifrance Registry Study: Effectiveness and Safety of Defibrotide in the Treatment of Hepatic Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome after Hematopoietic Cell Transplantation

Hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a potentially fatal complication that occurs after hematopoietic cell transplantation (HCT) conditioning. In its most severe form, VOD/SOS is associated with multi-organ failure (MOF) and a mortality rate of >80% if untreated. Defibrotide is approved for the treatment of hepatic VOD/SOS with renal or pulmonary dysfunction post-HCT in adult and pediatric patients in the United States and severe hepatic VOD/SOS post-HCT in patients aged >1 month in the European Union. The DEFIFrance study collected real-world data on the safety and effectiveness of defibrotide in France. This analysis presents final primary data on the subgroup of DEFIFrance patients who received defibrotide for the treatment of severe/very severe VOD/SOS post-HCT.

This post-marketing study collected retrospective and prospective real-world data on patients receiving defibrotide at 53 HCT centers in France from July 15, 2014 to March 31, 2020. VOD/SOS severity was categorized using European Society for Blood and Marrow Transplantation criteria (adults) or study steering committee member adjudication (pediatric patients). The primary endpoints included Kaplan-Meier (KM)-estimated Day 100 (post-HCT) survival and Day 100 complete response (CR; total serum bilirubin <2 mg/dL and MOF resolution per investigators' assessment) in patients with severe/very severe VOD/SOS post-HCT. Secondary endpoints included evaluation of adverse events (AEs) of interest, such as hemorrhage, coagulopathy, injection-site reactions, infections, and thromboembolic events, irrespective of their relationship to treatment.

Of the 775 defibrotide-treated patients included in the study analysis, 250 received defibrotide for the treatment of severe/very severe VOD/SOS post-HCT (severe: 119 [48%]; very severe: 131 [52%]). The median patient age was 45 years (range: 5 months, 74 years) and 52 (21%) patients were less than 18 years of age. A total of 219 (88%) patients had received allogeneic HCT and 95 (38%) patients had an unrelated donor. The Day 100 KM-estimated survival was 58% (95% confidence interval [CI]: 52%, 64%) in patients with severe/very severe VOD/SOS post-HCT. The estimated Day 100 survival rate was higher in patients with severe (74% [95% CI: 65%, 81%]) versus very severe (43% [95% CI: 35%, 52%]) VOD/SOS. Among patients with severe/very severe VOD/SOS post-HCT, the CR rate at Day 100 was 53% (95% CI: 47%, 59%). The Day 100 CR rate was higher in patients with severe (68% [95% CI: 60%, 77%]) versus very severe (39% [95% CI: 30%, 47%]) VOD/SOS. Treatment emergent AEs of interest occurred in 41% of patients with severe/very severe VOD/SOS, with infection (23%) and bleeding (17%) being the most commonly reported.

The DEFIFrance study represents the largest collection of real-world data on the use of defibrotide. The effectiveness and safety observed in this study build upon prior studies supporting the utility of defibrotide for treating severe/very severe VOD/SOS post-HCT in a real-world setting. Among patients receiving defibrotide for VOD/SOS post-HCT, outcomes were better in patients with severe versus very severe disease, highlighting the importance of early diagnosis and treatment of VOD/SOS before patients reach the most severe stage of VOD/SOS.