Abstract: Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a potentially life-threatening complication of haematopoietic cell transplantation (HCT) conditioning. The DEFIFrance post-marketing registry study evaluated effectiveness and safety in patients who received defibrotide. It collected retrospective/prospective patient data from 53 French HCT centres from July 2014 to March 2020. Primary endpoints were survival and complete response (CR; total serum bilirubin 〈 2 mg/dL, multiorgan failure resolution) at Day 100 post-HCT among patients with severe/very severe VOD/SOS. A secondary endpoint was evaluation of treatment-emergent serious adverse events (TESAEs) of interest. Of 798 patients analysed, 251 and 81 received defibrotide treatment for severe/very severe VOD/SOS and mild/moderate VOD/SOS post-HCT, respectively; 381 received defibrotide for VOD/SOS prophylaxis. In patients with severe/very severe VOD/SOS post-HCT, Kaplan–Meier–estimated CR at Day 100 was 74% (95% confidence interval [CI]: 66%, 81%). At Day 100, 137/251 (55%) were alive and in CR. Kaplan–Meier–estimated Day 100 post-HCT survival was 61% (95% CI: 55%, 67%) in patients with severe/very severe VOD/SOS. TESAEs of interest occurred in 29% of these patients; VOD/SOS-related mortality at 12 months was 15%. DEFIFrance represents the largest collection of real-world data on post-registration defibrotide use, supporting the real-world utility of defibrotide for patients with severe/very severe VOD/SOS post-HCT.

Abstract: 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 & gt;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 & gt;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 & lt;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. Disclosures Mohty: Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Stemline: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding, Speakers Bureau. Yakoub-Agha:Celgene: Honoraria; Novartis: Honoraria; Gilead/Kite: Honoraria, Other: travel support; Jazz Pharmaceuticals: Honoraria; Janssen: Honoraria. Labopin:Jazz Pharmaceuticals: Honoraria. Blaise:Jazz Pharmaceuticals: Honoraria. Renard:Jazz Pharmaceuticals: Research Funding. Jubert:Jazz Pharmaceuticals: Research Funding. Ryan:Jazz Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Bouvatier:Jazz Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Dalle:Bellicum: Consultancy, Honoraria; Sanofi-Genzyme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Medac: Consultancy, Honoraria; Gilead: Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orchard: Consultancy, Honoraria; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Peffault De Latour:Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Alexion Pharmaceuticals Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Apellis: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

Abstract: Introduction: Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a potentially life-threatening complication of hematopoietic cell transplantation (HCT) conditioning that may also develop after high-dose chemotherapy. Multiorgan failure (MOF) is associated with the most severe form of VOD/SOS and, if untreated, may result in a mortality rate of & gt;80%. Defibrotide is approved for the treatment of hepatic VOD/SOS with renal or pulmonary dysfunction post-HCT in the US and for severe hepatic VOD/SOS post-HCT in patients aged & gt;1 month (mo) in the EU. The DEFIFrance study collected real-world data on the efficacy and safety of defibrotide from HCT centers in France. This analysis presents final, long-term data on the primary study population: patients who received defibrotide treatment for severe/very severe VOD/SOS post-HCT. Methods: This post-marketing registry study collected retrospective and prospective real-world data on patients receiving defibrotide at 53 HCT centers in France. Diagnosis of VOD/SOS was at the investigator's discretion using standard criteria, per typical clinical practice. Disease severity was categorized using adult EBMT severity criteria in patients aged ≥18 years (y), and patients aged & lt;18 y were retrospectively/prospectively categorized using pediatric EBMT severity criteria. The primary endpoints were Day 100 post-HCT survival and complete response (CR; total serum bilirubin & lt;2 mg/dL and MOF resolution per investigators' assessment) in patients with severe/very severe VOD/SOS. A secondary endpoint was the evaluation of treatment-emergent serious adverse events (SAEs) of interest: hemorrhage, coagulopathy, injection-site reactions, infections, and thromboembolic events, irrespective of relationship to treatment. Results: Of 798 defibrotide-treated patients enrolled in the study, 251 patients received defibrotide for the treatment of severe/very severe VOD/SOS post-HCT (severe: 117 [47%]; very severe: 134 [53%] ). Median age was 45 y (range: 0, 74) and 58 (23%) patients were & lt;18 y of age. The most common primary diagnoses were acute myeloid leukemia (68 [27%]) and acute lymphoblastic leukemia (49 [20%] ). Common ( & gt;50%) risk factors included prior treatment with hepatotoxic drugs (150 [60%]), iron overload (133 [58%] ), and relapsed/refractory disease (137 [55%]). Risk factors of interest included prior HCT (29/239 [12%] ), and prior treatment with gemtuzumab ozogamicin (17/251 [7%]) and inotuzumab ozogamicin (6/251 [2%] ). At diagnosis, 55/250 (22%) patients had anicteric VOD/SOS (bilirubin levels ≤2 mg/dL). Median (range) time from VOD/SOS diagnosis to defibrotide administration was 0 (-1, 24) days. The Kaplan-Meier (KM)-estimated Day 100 post-HCT survival rate was 61% (95% confidence interval [CI]: 55%, 67%) in patients with severe/very severe VOD/SOS, with a higher survival rate seen in patients with severe versus very severe disease. The post-HCT survival rate in patients with se vere/very severe VOD/SOS was 50% at 6 mo and 43% at 12 mo (Figure). KM-estimated survival rates at 6 and 12 mo were also higher for those with severe versus very severe disease (Figure). The KM-estimated CR rate by Day 100 among patients with severe/very severe VOD/SOS post-HCT was 74% (95% CI: 66%, 81%). Similar to the pattern observed for the survival rate, a higher CR rate was observed by Day 100 in patients with severe (84% [95% CI: 74, 92]) versus very severe (63% [95% CI: 52, 74] ) VOD/SOS. Treatment-emergent SAEs of interest occurred in 29% of patients with severe/very severe VOD/SOS post-HCT; the most common (≥2%) treatment-emergent SAE categories were infection (17%), hemorrhage (16%), and hypotension (2%). Mortality due to VOD/SOS at 12 mo was 15%. Conclusions: The DEFIFrance study represents the largest collection of real-world data on post-registration use of defibrotide. The efficacy and safety observed in this study add to evidence from prior studies supporting the utility of defibrotide for treating patients with 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 VOD/SOS, highlighting the importance of early VOD/SOS diagnosis and treatment, before patients reach the most severe stage of VOD/SOS. Figure 1 Figure 1. Disclosures Mohty: Sanofi: Honoraria, Research Funding; Pfizer: Honoraria; Novartis: Honoraria; Takeda: Honoraria; Jazz: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria; Celgene: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Astellas: Honoraria; Amgen: Honoraria; Adaptive Biotechnologies: Honoraria. Blaise: Jazz Pharmaceuticals: Honoraria. Peffault De Latour: Amgen: Consultancy, Other, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; Alexion, AstraZeneca Rare Disease: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; Jazz Pharmaceuticals: Honoraria. Labopin: Jazz Pharmaceuticals: Honoraria. Detrait: Jazz Pharmaceuticals: Research Funding. Huynh: Jazz Pharmaceuticals: Honoraria. Renard: Jazz Pharmaceuticals: Research Funding. Asubonteng: Jazz Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Delaval: Jazz Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Yakoub-Agha: Jazz Pharmaceuticals: Honoraria. Dalle: Jazz Pharmaceuticals: Honoraria.