Verification of the Prediction Accuracy of a Biomarker-Based Prognostic for Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome (VOD/SOS) After Hematopoietic Cell Transplantation (HCT).

BACKGROUND: Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a potentially life-threatening complication of hematopoietic cell transplantation (HCT), especially in severe cases. Patient outcomes are improved with prompt treatment; however, diagnosing this disease is challenging as many clinical symptoms of VOD/SOS overlap with other post-HCT complications. A biomarker-based prognostic test for the assessment of VOD/SOS risk, termed "VODCheck" was developed in a previous study but has not yet been validated. OBJECTIVE: This study aimed to validate the accuracy of VODCheck as a prognostic test for VOD/SOS in an independent cohort of patients. STUDY DESIGN: VODCheck incorporates hyaluronan (HA), angiopoietin-2 (ANG-2), and thrombomodulin (TM) based on their association with VOD/SOS, their analytical characteristics, and their ability to complement each other in a multivariate prognostic model. To validate VODCheck we measured plasma biomarker levels from a subset of patients enrolled in the control arm of a phase 3 study that tested VOD/SOS prophylaxis. We used a hierarchical design with prespecified primary (day 7), secondary A (day 15), and secondary B (day 1) hypotheses to verify the prognostic accuracy of VODCheck post-HCT. The cases of VOD/SOS (n = 22) were age-matched ∼1:3 with controls (n = 65). RESULTS: VODCheck was prognostic of VOD/SOS risk at all 3 time points with an area under the curve (AUC) of .815 (P < .001) for day 7, .836 (P < .001) for day 15, and .706 (P = .002) for day 1 post-HCT. A multivariate analysis confirmed the prognostic accuracy of VODCheck after adjustment for confounders such as age, VOD/SOS risk status, primary disease, and ozogamicin treatment. CONCLUSION: VODCheck was validated as an independent predictor of risk for VOD/SOS within 15 days post-HCT and appears to provide clinicians with actionable information to improve patient care.

Diagnosing and Grading of Sinusoidal Obstructive Syndrome after Hematopoietic Stem Cell Transplant of Children, Adolescent and Young Adults treated in a Pediatric Institution with Pediatric Protocols.

Sinusoidal obstructive syndrome (SOS), or veno-occlusive disease, of the liver has been recognized as a complex, life-threatening complication in the posthematopoietic stem cell transplant (HSCT) setting. The diagnostic criteria for SOS have evolved over the last several decades with a greater understanding of the underlying pathophysiology, with 2 recent diagnostic criteria introduced in 2018 (European Society of Bone Marrow Transplant [EBMT] criteria) and 2020 (Cairo criteria). We sought out to evaluate the performance characteristics in diagnosing and grading SOS in pediatric patients of the 4 different diagnostic criteria (Baltimore, Modified Seattle, EBMT, and Cairo) and severity grading systems (defined by the EBMT and Cairo criteria). Retrospective chart review of children, adolescent, and young adults who underwent conditioned autologous and allogeneic HSCT between 2017 and 2021 at a single pediatric institution. A total of 250 consecutive patients underwent at least 1 HSCT at UCSF Benioff Children's Hospital San Francisco for a total of 307 HSCT. The day 100 cumulative incidence of SOS was 12.1%, 21.1%, 28.4%, and 28.4% per the Baltimore, Modified Seattle, EBMT, and Cairo criteria, respectively (P < .001). We found that patients diagnosed with grade ≥4 SOS per the Cairo criteria were more likely to be admitted to the Pediatric Intensive Care Unit (92% versus 58%, P = .035) and intubated (85% versus 32%, P = .002) than those diagnosed with grade ≥4 per EBMT criteria. Age <3 years-old (HR 1.76, 95% [1.04 to 2.98], P = .036), an abnormal body mass index (HR 1.69, 95% [1.06 to 2.68], P = .027), and high-risk patients per our institutional guidelines (HR 1.68, 95% [1.02 to 2.76], P = .041) were significantly associated with SOS per the Cairo criteria. We demonstrate that age <3 years, abnormal body mass index, and other high-risk criteria associate strongly with subsequent SOS development. Patients with moderate to severe SOS based on Cairo severity grading system may correlate better with clinical course based on ICU admissions and intubations when compared to the EBMT severity grading system.

sVEGF-R1 in acute non-infectious toxicity syndromes after pediatric allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (HSCT) is challenged by acute non-infectious toxicities, including sinusoidal obstruction syndrome (SOS), engraftment syndrome (ES) and capillary leak syndrome (CLS) among others. These complications are thought to be driven by a dysfunctional vascular endothelium, but the pathophysiological mechanisms remain incompletely understood, and the diagnoses are challenged by purely clinical diagnostic criteria that are partly overlapping, limiting the possibilities for progress in this field. There is, however, increasing evidence suggesting that these challenges may be met through the development of diagnostic biomarkers to improve diagnostic accuracy of pathogenetically homogenous entities, improved pre-transplant risk assessment and the early identification of patients with increased need for specific treatment. Soluble vascular endothelial growth factor receptor-1 (sVEGF-R1) is emerging as an important biomarker of endothelial damage in patients with trauma and sepsis but has not been studied in HSCT. OBJECTIVES: To investigate sVEGF-R1 as a marker of endothelial damage in pediatric HSCT patients by exploring associations with SOS, CLS, ES, and acute graft-versus-host disease (aGvHD). METHODS: We prospectively included 113 children undergoing myeloablative HSCT and measured sVEGF-R1 in plasma samples obtained weekly during the early period of transplantation and 3 months post-transplant. RESULTS: All over, sVEGF-R1 levels were significantly increased from day +7 after graft infusion, peaking at day +30, most pronounced in patients receiving busulfan. Patients considered to be at increased risk of SOS and therefore commenced on prophylactic defibrotide had significantly elevated levels of sVEGF-R1 before start of conditioning (446 pg/mL vs. 281 pg/mL, p = 0.0035), and this treatment appeared to stabilize sVEGF-R1 levels compared to patients not treated with defibrotide. Thirteen (11.5%) children meeting the modified Seattle criteria for SOS at median day +8 (1-18), had significantly elevated sVEGF-R1 levels on day +14 (489 pg/mL vs. 327 pg/mL, p = 0.007). In contrast. sVEGF-R1 levels in the much broader group of patients (45.1%) meeting EBMT-SOS criteria, including patients with very mild disease, did not overall differ in sVEGF-R1 levels, but higher sVEGF-R1 levels were seen in EBMT-SOS patients with an increased need for diuretic treatment. Importantly, sVEGF-R1 levels were not associated with ES and CLS but were significantly increased on day +30 in patients with grade III-IV aGvHD (OR = 4.2 pr. quartile, p = 0.023). CONCLUSION: VEGF-R1 levels are found to be increased in pediatric patients developing SOS, reflecting the severity of morbidity. sVEGF-R1 were unassociated with both CLS and ES. The potential of sVEGF-R1 as a clinically useful biomarker for SOS should be further explored to improve pre-transplant SOS-risk assessment, SOS-severity grading, and to guide treatment.

Endothelial cell activation mediated by cold ischemia-released mitochondria is partially inhibited by defibrotide and impacts on early allograft function following liver transplantation.

DAMPs (danger-associated molecular patterns) are self-molecules of the organism that appear after damage. The endothelium plays several roles in organ rejection, such as presenting alloantigens to T cells and contributing to the development of inflammation and thrombosis. This study aimed to assess whether DAMPs present in the organ preservation solution (OPS) after cold ischemic storage (CIS) contribute to exacerbating the endothelial response to an inflammatory challenge and whether defibrotide treatment could counteract this effect. The activation of cultured human umbilical vein endothelial cells (HUVECs) was analyzed after challenging with end-ischemic OPS (eiOPS) obtained after CIS. Additionally, transwell assays were performed to study the ability of eiOPS to attract lymphocytes across the endothelium. The study revealed that eiOPS upregulated the expression of MCP-1 and IL-6 in HUVECs. Moreover, eiOPS increased the membrane expression of ICAM-1and HLA-DR, which facilitated leukocyte migration toward a chemokine gradient. Furthermore, eiOPS demonstrated its chemoattractant ability. This activation was mediated by free mitochondria. Defibrotide was found to partially inhibit the eiOPS-mediated activation. Moreover, the eiOPS-mediated activation of endothelial cells (ECs) correlated with early allograft dysfunction in liver transplant patients. Our finding provide support for the hypothesis that mitochondria released during cold ischemia could trigger EC activation, leading to complications in graft outcomes. Therefore, the analysis and quantification of free mitochondria in the eiOPS samples obtained after CIS could provide a predictive value for monitoring the progression of transplantation. Moreover, defibrotide emerges as a promising therapeutic agent to mitigate the damage induced by ischemia in donated organs.

Role of Defibrotide in the Prevention of Murine Model Graft-versus-Host Disease after Allogeneic Hematopoietic Cell Transplantation.

Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Vascular endothelial cells are entirely exposed and damaged during the pathogenesis of acute GVHD (aGVHD). Defibrotide (DF) is a mixture of single-stranded oligonucleotides that has several pharmacologic effects that contribute to its endothelial protective properties. B10.BR mice were conditioned, followed by the infusion of donor C57BL/6J T cell-depleted bone marrow cells with or without splenocytes. The mice were either treated with DF or appropriate controls daily for the first week and then 3 times per week thereafter. Allogeneic DF-treated recipients demonstrated significantly better survival with reduced clinical GVHD. Significantly reduced organ pathology in the gut was associated with significantly decreased T cell infiltration in the ileum and colon on day +28. Serum cytokine analysis revealed significantly reduced levels of TNF and IL-6 at day +7 and of TNF at day +28 in allogeneic DF-treated recipients. Significantly reduced levels of ICAM-1 and angiopoietin-2 in serum and reduced VCAM-1 and HCAM levels in the ileum and colon of allogeneic DF-treated recipients were observed. Improved survival was seen in the graft-versus-leukemia (GVL) model (C3H.SW into C57BL/6J mice with C1498-luc). Through its anti-inflammatory and endothelial protective effects, DF treatment reduces the severity of aGVHD while not impairing GVL activity.

Incidence of Sinusoidal Obstruction Syndrome/Veno-Occlusive Disease and Treatment with Defibrotide in Allogeneic Transplantation: A Multicenter Australasian Registry Study.

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) is an established complication in patients undergoing allogeneic hemopoietic stem cell transplantation (HSCT). Defibrotide is an effective and safe pharmacologic option for treating diagnosed SOS/VOD. By exploring data provided to the Australasian Bone Marrow Transplant Recipient Registry (ABMTRR) by centers in Australia and New Zealand, this study aimed to describe the incidence of SOS/VOD and patterns of defibrotide use from 2016 to 2020. Patients who underwent allogeneic hemopoietic stem cell transplantation between 2016 and 2020 were identified from the ABMTRR. Data were extracted for a total of 3346 patients, 2692 from adult centers and 654 from pediatric centers, with a median follow-up of 21.5 months and 33.3 months, respectively. Descriptive statistics were used to describe the patient population, including the incidence of SOS/VOD and defibrotide use. Comparisons were made between patients without SOS/VOD and those with SOS/VOD, divided into defibrotide and no defibrotide cohorts. Associations with overall survival (OS) and day 100 survival with such variables as sex, age, disease at transplantation, stem cell source, conditioning agents, SOS/VOD diagnosis, and use of defibrotide, were determined. The reported incidence of SOS/VOD was 4.1% in adult centers and 11.5% in pediatric centers. Defibrotide was administered to 74.8% of adult patients and 97.3% of pediatric patients with SOS/VOD. Significant variability in the use, dosage, and duration of defibrotide was seen across the adult centers. The day 100 survival rate and median OS for patients managed with defibrotide was 51.8% and 103 days, respectively, for adult patients and 90.4% and not reached, respectively, for pediatric patients. In adults, older age at transplantation, an HLA-matched nonsibling relative donor, and a diagnosis of SOS/VOD treated with defibrotide were associated with reduced OS. In pediatric patients, the patient and transplantation characteristics associated with reduced OS were a diagnosis of SOS/VOD and a ≥2 HLA-mismatched related donor. A collaborative approach across Australasia to diagnosing and managing SOS/VOD, particularly with respect to consistent defibrotide use, is recommended.

Molecular Advances in Sinusoidal Obstruction Syndrome/Veno-Occlusive Disease.

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) detected in the liver has been considered a severe complication of hematopoietic stem cell transplantation (HSCT). SOS/VOD is characterized by hepatomegaly, right upper quadrant pain, jaundice, and ascites. The severe forms of the disease may result in multi-organ dysfunction (MOD) with a high mortality rate (>80%). The development of SOS/VOD can be rapid and unpredictable. Therefore, early identification and severity assessment is crucial in facilitating prompt diagnosis and timely treatment. Effective treatment and potential prophylaxis with defibrotide highlight the need for characterizing a sub-group of patients at high risk for SOS/VOD. Moreover, antibodies that are conjugated with calicheamicin, gemtuzumab, and inotuzumab ozogamicin, have led to renewed interest in this syndrome. Evaluation and management of serious adverse events associated with gemtuzumab and inotuzumab ozogamicin are recommended. We review hepatic-, transplant- and patient-related risk factors, criteria for diagnosis and grading classification, and SOS/VOD potential biomarkers. Furthermore, we examine pathogenesis, clinical presentation, diagnostic criteria, risk factors, prophylaxis, and treatment of SOS/VOD occurring post HSCT. Moreover, we aim to provide an up-to-date summary of molecular advances in the diagnosis and management of SOS/VOD. We performed a comprehensive review of the literature and examined the recently available data, mostly using the PubMed and Medline search engines for original articles published over the last decade. In the era of precision medicine, our review provides up-to-date knowledge of genetic or sera markers for SOS/VOD with the goal of identifying a subset of high-risk patients.

Defibrotide mitigates endothelial cell injury induced by plasmas from patients with COVID-19 and related vasculopathies.

BACKGROUND AND OBJECTIVES: COVID-19 progression is characterized by systemic small vessel arterial and venous thrombosis. Microvascular endothelial cell (MVEC) activation and injury, platelet activation, and histopathologic features characteristic of acute COVID-19 also describe certain thrombotic microangiopathies, including atypical hemolytic-uremic syndrome (aHUS), thrombotic thrombocytopenic purpura (TTP), and hematopoietic stem cell transplant (HSCT)-associated veno-occlusive disease (VOD). We explored the effect of clinically relevant doses of defibrotide, approved for HSCT-associated VOD, on MVEC activation/injury. METHODS: Human dermal MVEC were exposed to plasmas from patients with acute TMAs or acute COVID-19 in the presence and absence of defibrotide (5µg/ml) and caspase 8, a marker of EC activation and apoptosis, was assessed. RNAseq was used to explore potential mechanisms of defibrotide activity. RESULTS: Defibrotide suppressed TMA plasma-induced caspase 8 activation in MVEC (mean 60.2 % inhibition for COVID-19; p = 0.0008). RNAseq identified six major cellular pathways associated with defibrotide's alteration of COVID-19-associated MVEC changes: TNF-α signaling; IL-17 signaling; extracellular matrix (ECM)-EC receptor and platelet receptor interactions; ECM formation; endothelin activity; and fibrosis. Communications across these pathways were revealed by STRING analyses. Forty transcripts showing the greatest changes induced by defibrotide in COVID-19 plasma/MVEC cultures included: claudin 14 and F11R (JAM), important in maintaining EC tight junctions; SOCS3 and TNFRSF18, involved in suppression of inflammation; RAMP3 and transgelin, which promote angiogenesis; and RGS5, which regulates caspase activation and apoptosis. CONCLUSION: Our data, in the context of a recent clinical trial in severe COVID-19, suggest benefits to further exploration of defibrotide and these pathways in COVID-19 and related endotheliopathies.

Prognostic Biomarkers for Hepatic Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome in Myeloablative Allogeneic Hematopoietic Cell Transplantation: Results from the Blood and Marrow Transplant Clinical Trials Network 1202 Study.

Hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a potentially life-threatening complication of hematopoietic cell transplantation (HCT). This study aimed to determine a blood biomarker signature early post-HCT that identifies patients at high risk for VOD/SOS. A set of 23 plasma biomarkers, selected from the VOD/SOS literature, was measured on days 0, 7, and 14 after myeloablative HCT using blood samples from patients enrolled in the Blood and Marrow Transplant Clinical Trials Network (BMT CTN) Protocol 1202. Eligible cases were diagnosed with VOD/SOS in BMT CTN 1202 using the Baltimore criteria. Controls (without VOD/SOS) were matched to cases for conditioning regimen and age. Significant biomarkers were identified using the Bonferroni-adjusted Wilcoxon rank-sum test (P ≤ .002). Thirty-three patients with mild or severe VOD/SOS were identified (cases) and matched to 107 controls. Two, 8, and 5 biomarkers measured from the plasma of these patients were significantly associated with the development of VOD/SOS at days 0, 7, and 14, respectively, with the strongest associations on days 7 and 14. Biomarker associations were stronger for severe VOD/SOS risk and were stronger prognostic markers for VOD/SOS cases occurring within 28 days of HCT. Hyaluronan was most strongly associated with VOD/SOS risk, with an area under the receiver operating characteristic curve (AUC) of .81 on day 7 and .79 on day 14. Multivariate models of up to 5 biomarkers generated AUCs ranging from .82 to .85. All associations with VOD/SOS risk were independent of clinical risk factors. This study confirms previously identified biomarkers of VOD/SOS risk and identified novel prognostic biomarker signatures that identify patients at risk for VOD/SOS shortly after HCT. Multivariate analysis suggests that a combination of up to 5 of these protein biomarkers may provide a prognostic tool for identifying patients at risk for VOD/SOS.

Defibrotide improved the outcome of monocrotaline induced rat hepatic sinusoidal obstruction syndrome.

BACKGROUND AND AIM: Pyrrolizidine alkaloids (PA) induced hepatic sinusoidal obstruction syndrome (HSOS) occurred worldwide and the mortality rate remained high because there were no specific therapies. Defibrotide was effective for HSOS following hematopoietic stem cell transplantation. But the pathogenesis of the two types of HSOS were not equivalent. The purpose of this study was to see if defibrotide was also effective in PA induced rat HSOS. METHODS: First we improved rat HSOS model by using higher dose (230 mg/kg) of monocrotaline (a kind of PA) as the dose of median lethal dose. So drug effectiveness could be assessed by survival time. Next, male SD rats were divided into 5 groups. They were control group, model group, low dose low molecular weight heparin (LMWH) treatment group, high dose LMWH treatment group and defibrotide treatment group. Rats' survival time, liver function, white blood cell count and cytokines were compared among the groups. The DeLeve score was used to assess the severity of liver pathology. RESULTS: The model group exhibited typical liver pathology of HSOS, such as hepatic sinus dilation, congestion, endothelial injury of central lobular vein, coagulative necrosis of hepatocytes and fibrin deposition in the subendothelial. The pathologic characteristics indicated that the model was built up successfully. The survival rate was significantly higher in defibrotide group (81.8%) than model group (43.7%), while the survival rates were similar in the two LMWH groups (62.5% and 75%) and model group. The survival time only be prolonged by defibrotide (P=0.028) but not LMWH (P>0.05). DeLeve score was improved most in the defibrotide group than the two LMWH groups (both P<0.01). Changes in DeLeve score, liver function, plasma level of tumor necrosis factor α and plasminogen activator inhibitor-1 exhibited the same trends. CONCLUSION: Defibrotide could improve the outcome of monocrotaline-induced rat HSOS indicating that defibrotide might be a better choice than LMWH in clinical practice.

Interest of the preventive and curative use of defibrotide on the occurrence and severity of sinusoidal obstruction syndrome after hematopoietic stem cell transplant in children.

Defibrotide (DF) is indicated for the treatment of severe sinusoidal obstruction syndrome (SOS) following hematopoietic stem cell transplantation (HSCT), but its prophylactic use against SOS is not recommended yet. This study describes the impact of the preventive and curative use of DF on reducing the incidence and severity of SOS in children. Patients aged 0-19 years, who received allogenic HSCT after myeloablative conditioning regimen with busulfan or total body irradiation in our comprehensive cancer center, between 2013 and 2017, were included. The Baltimore or modified Seattle criteria were used for SOS diagnosis. SOS was graded using the 2017 European Society for Blood and Marrow Transplantation classification defining severity criteria of SOS in children. SOS occurrence tended to decrease with prophylactic DF, but no significant difference was observed in terms of severity. When not treated with preventive DF, 50% (19/38) of the patients with SOS were graded severe to very severe, but only 37% (7/19) had organ dysfunction. Curative DF was administered at a median of 2 days post-HSCT, for a median of 6.5 days. The absence of fatal SOS supports the use of early curative DF with acceptable toxicities and questions the optimal duration of DF treatment.

A stitch in time saves nine: timely use of N-acetyl cysteine (NAC) for chemotherapy-induced veno-occlusive disease (VOD)-is it a cost-effective alternative?

Chemotherapy-induced veno-occlusive disease (VOD) is a rare liver dysfunction seen among pediatric cancer patients which could lead to severe morbidity and mortality. Defibrotide is the commonly used antidote in the management of both stem cell transplant and chemotherapy-associated VOD along with liver supportive measures. Defibrotide is costly and generally not accessible to majority of patients treated at resource poor settings. In this report, we describe the successful management of chemotherapy-induced VOD with timely administration of N-acetyl cysteine.

Defibrotide Shows Efficacy in the Prevention of Sinusoidal Obstruction Syndrome After Allogeneic Hematopoietic Stem Cell Transplantation: A Retrospective Study.

Sinusoidal obstruction syndrome (SOS), also known as hepatic veno-occlusive disease (VOD), is a well-known complication of allogeneic hematopoietic stem cell transplantation (HSCT) associated with a mortality rate of up to 85%.  Defibrotide has shown efficacy in treatment of SOS/VOD. Moreover, evidence exists supporting the efficacy of defibrotide as SOS/VOD prophylaxis. We have previously reported our single center experience on 52 HSCT recipients receiving defibrotide as SOS/VOD prophylaxis, which has shown that the patients did not develop any SOS/VOD under this prophylaxis. The aim of the present study was to see if we can confirm the previous results, mainly on the decrease incidence of SOS/VOD, as well as improve event-free survival (EFS) on a larger study population. We extended our previous study in a single-center retrospective analysis to include 237 consecutive patients (248 transplantations) who underwent transplantation between 1999 and 2009 for hematological diseases and receiving intravenous defibrotide as prophylaxis. This cohort was compared to 241 patients (248 transplantations) treated before 1999 or after 2009 when defibrotide prophylaxis was not routinely used in our center. Median follow-up for the study group was 10 (range 2-16) years and for the control group 2.7 (range 1-18) years. None of the 237 patients in the defibrotide group developed SOS/VOD. The cumulative incidence (CI) of SOS/VOD was 0% in the defibrotide group as compared to 4.8% (95% confidence interval [CI], 2.6-8%; P= .00046) in the control group. There was also a better 1-year EFS with 38% (95% CI, 32%-44%) in the defibrotide group versus 28% (95% CI, 22%-34%) (P= .00969) and decreased cumulative incidence of acute graft-versus-host disease (GvHD) in the defibrotide group 31% (95% CI, 25%-37%) versus 42% (95% CI, 36%-48%) (P= .026). The 1-year overall survival, relapse incidence, and non-relapse mortality were not statistically different. Multivariable analysis, performed taking into account clinical factors known to influence the risk of SOS/VOD, confirmed the favorable impact of defibrotide on SOS/VOD (HR 1.38e-08 [95% CI, 3.28e-09-5.80e-08]; P< .00001). Conversely, multivariable analysis failed to confirm the impact of defibrotide on 1-year EFS or acute GvHD. This large retrospective study on SOS/VOD-prophylaxis with defibrotide suggests that this approach may be of benefit. These results need to be confirmed in a prospective randomized trial.

Defibrotide Prophylaxis of Sinusoidal Obstruction Syndrome in Adults Treated With Inotuzumab Ozogamicin Prior to Hematopoietic Stem Cell Transplantation.

Sinusoidal Obstruction Syndrome (SOS) is a life threatening HSCT complication and it can rapidly evolve in Multiple Organ Dysfunction Syndrome, with a mortality exceeding 80%. Early treatment with defibrotide is the leading factor for efficacy. Its prophylactic use is recommended in the pediatric setting, but its value isn't validated for adults, although factors for individual risk assessment are debated. We here present a real-world experience of Defibrotide prophylaxis in adults at very high risk of SOS. We treated with prophylactic Defibrotide and Ursodeoxycholic Acid seven patients receiving allogeneic HSCT for high risk B-ALL, previously treated with single agent Inotuzomab-Ozogamicin. They all had other high risk factors for SOS such as previous hepatotoxicity, previous allo-HSCT, double alkylating conditioning. All patients received Treosulfan-Fludarabine conditioning, Thiotepa was added in 4 patients and 4GyTBI in 2 patients. GvHD prophylaxis included post-transplant cyclophosphamide, rapamycin and mycophenolate. Donor source was PBSC. Five patients received family MMRD transplant, 1 patient a MRD transplant and 1 patient a MUD transplant. Non-severe gastrointestinal bleeding occurred in two patients requiring defibrotide temporarily discontinuation. SOS occurred in 3/7 cases within 21 days after HSCT and no late-onset SOS were diagnosed. SOS caused death in all cases. All three patients were characterized by a common pattern of very high risk factors by prior HSCT, they all received a myeloablative conditioning with Treosulfan-Thiotepa and a MMRD transplant. Defibrotide prophylaxis apparently failed to protect against the development of SOS in those patients treated with a double alkylator-based conditioning regimen, while a possible efficacy for the other high-risk patients is debatable.

Defibrotide Therapy for SARS-CoV-2 ARDS.

BACKGROUND: SARS-CoV-2-related ARDS is associated with endothelial dysfunction and profound dysregulation of the thrombotic-fibrinolytic pathway. Defibrotide is a polyanionic compound with fibrinolytic, antithrombotic, and antiinflammatory properties. RESEARCH QUESTION: What is the safety and tolerability of defibrotide in patients with severe SARS-CoV-2 infections? STUDY DESIGN AND METHODS: We report a prospective, open-label, single-center safety trial of defibrotide for the management of SARS-CoV-2-related ARDS. Eligible participants were 18 years of age or older with clinical and radiographic signs of ARDS, no signs of active bleeding, a serum D-dimer of more than twice upper limit of normal, and positive polymerase chain reaction-based results for SARS-CoV-2. Defibrotide (6.25 mg/kg/dose IV q6h) was administered for a planned 7-day course, with serum D-dimer levels and respiratory function monitored daily during therapy. RESULTS: Twelve patients (median age, 63 years) were treated, with 10 patients receiving mechanical ventilation and 6 receiving vasopressor support at study entry. The median D-dimer was 3.25 µg/ml (range, 1.33-12.3) at study entry. The median duration of therapy was 7 days. No hemorrhagic or thrombotic complications occurred during therapy. No other adverse events attributable to defibrotide were noted. Four patients met the day 7 pulmonary response parameter, all four showing a decrease in serum D-dimer levels within the initial 72 h of defibrotide therapy. Three patients died of progressive pulmonary disease 11, 17, and 34 days after study entry. Nine patients (75%) remain alive 64 to 174 days after initiation of defibrotide. Day 30 all-cause mortality was 17% (95% CI, 0%-35%). All patients with a baseline Pao2 to Fio2 ratio of ≥ 125 mm Hg survived, whereas the three patients with a baseline Pao2 to Fio2 ratio of < 125 mm Hg died. INTERPRETATION: The use of defibrotide for management of SARS-CoV-2-related ARDS proved safe and tolerable. No hemorrhagic or thrombotic complications were reported during therapy, with promising outcomes in a patient population with a historically high mortality rate. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT04530604; URL: www. CLINICALTRIALS: gov.

Effectiveness of defibrotide in the prevention of hepatic venooclusive disease among adult patients receiving allogeneic hematopoietic cell transplantation: A retrospective single center experience.

Hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is one of the most life-threatening early complications following hematopoietic cell transplantation (HCT). Due to the high mortality rate of severe VOD/SOS accompanied with multiorgan failure, there is a great interest in preventive strategies. The efficacy of defibrotide (DF) on the prevention of VOD/SOS has been clearly shown in high-risk pediatric patients, but evidence-based data on adults is scarce. In this report, we aimed to assess the impact of DF on the incidence of VOD/SOS in our center by posttransplant day 30 among patients who were treated with allogeneic HCT (allo-HCT). The study included a total of 56 patiens (28 males, 28 females). The median age of the study cohort was 43 (20-68). The daily dose of DF was 10 mg/kg and 25 mg/kg in 53 (94.6 %) and 3 (5.3 %) patients, respectively. Patients also recieved oral ursodeoxycolic acid (UDCA) 250 mg three-times daily started with conditioning until D + 90. Twenty-three (41.1 %) patients had at least one major EBMT-defined risk factor for development of VOD/SOS. One patient who belonged to a very high-risk group (with at least two major risk factors) developed very-severe VOD/SOS at posttransplant D + 20 and died as a result of multiorgan failure. The cumulative incidence of VOD/SOS at D + 30 was 1.9 %. Our findings indicate that 10 mg/kg daily intravenous DF combined with UDCA is quite effective in prevention of VOD/SOS in patients who underwent first allo-HSCT.

Defibrotide combined with triple therapy including posttransplant cyclophosphamide, low dose rabbit anti-t-lymphocyte globulin and cyclosporine is effective in prevention of graft versus host disease after allogeneic peripheral blood stem cell transplantation for hematologic malignancies.

Endothelial dysfunction and damage play important roles in the pathophysiology of graft versus host disease (GvHD) and hepatic venoocclusive disease/sinusoidal obstruction syndrome (VOD/SOS). Preliminary evidence suggests that defibrotide (DF) may decrease the risk of GvHD. We speculated that DF prophylaxis may have a synergistic effect with other immunosupressive agents by decreasing the incidence of GvHD and retrospectively evaluated the impact of a DF prophylaxis on the development of GvHD. Thirty-eight adult patients with various hematological neoplasms who underwent peripheral blood allogeneic hematopoietic stem cell transplantation from all donor types were included. All patients received DF for prevention of VOD/SOS. GvHD prophylaxis included rabbit anti-T lymphocyte globulin (rATLG), posttransplant cyclophosphamide (PTCy) and cyclosporine (CsA). The median follow-up of the surviving patients was 484 (365-814) days. The cumulative incidence of grade III-IV acute GvHD and moderate/severe chronic GvHD requiring systemic immunosupression at 1 year were 20.6 % and 5.3 %, respectively. Non-relapse mortality, GvHD-relapse-free survival, and overall survival of the study cohort at 1-year were 21.1 %, 44.7 % and 57.9 %, respectively. Our preliminary results suggest that DF may act as a global endothelial protectant and decrease the risk of GvHD in combination with rATLG, PTCy and CsA.

Hepatic veno-occlusive disease (sinusoidal obstruction syndrome) after hematopoietic stem cell transplantation in adult patients: Diagnosis, incidence, prophylaxis, and treatment.

Hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) affecting the liver is a rare, possibly life-threatening complication of hematopoietic stem cell transplantation (HSCT). Sinusoidal endothelial cell (SEC) damage triggered by various factors (especially conditioning regimen) results in post sinusoidal portal hypertension due to obstruction of the hepatic vein. Diagnosis is guided by traditional clinical diagnostic criteria; the modified Seattle criteria, the Baltimore and revised European Group for Blood and Marrow Transplantation (EBMT), specifically. While there are promising results of imaging techniques studies in the diagnosis of VOD/SOS, none of those imaging techniques are routinely utilized in diagnosis yet. However, risk stratification is essential; conflicting results have been shown in studies aiming to define risk factors for development of VOD/SOS conducted to date. The only approved drug for the treatment of VOD/SOS yet is defibrotide, with early treatment offering higher chances of survival. In this review, we will focus on pathogenesis, clinical presentation and diagnostic criteria, risk factors, prophylaxis, and treatment of the VOD/SOS occurring post-HSCT.

Impact of Defibrotide in the Prevention of Acute Graft-Versus-Host Disease Following Allogeneic Hematopoietic Cell Transplantation.

BACKGROUND: Defibrotide is indicated for patients who develop severe sinusoidal obstructive syndrome following allogeneic hematopoietic cell transplantation (allo-HCT). Preclinical data suggested that defibrotide carries a prophylactic effect against acute graft-versus-host disease (aGVHD). OBJECTIVE: The purpose of this study was to investigate the effect of defibrotide on the incidence and severity of aGVHD. METHODS: This single-center retrospective study included all consecutive transplanted patients between January 2014 and December 2018. A propensity score based on 10 predefined confounders was used to estimate the effect of defibrotide on aGVHD via inverse probability of treatment weighting (IPTW). RESULTS: Of the 482 included patients, 64 received defibrotide (defibrotide group) and 418 did not (control group). Regarding main patient characteristics and transplantation modalities, the two groups were comparable, except for a predominance of men in the defibrotide group. The median age was 55 years (interquartile range [IQR]: 40-62). Patients received allo-HCT from HLA-matched related donor (28.6%), HLA-matched unrelated donor (50.8%), haplo-identical donor (13.4%), or mismatched unrelated donor (7.0%). Stem cell source was either bone marrow (49.6%) or peripheral blood (50.4%). After using IPTW, exposure to defibrotide was not significantly associated with occurrence of aGVHD (HR = 0.97; 95% CI 0.62-1.52; P = .9) or occurrence of severe aGVHD (HR = 1.89, 95% CI: 0.98-3.66; P = .058). CONCLUSION AND RELEVANCE: Defibrotide does not seem to have a protective effect on aGVHD in patients undergoing allo-HCT. Based on what has been reported to date and on these results, defibrotide should not be considered for the prevention of aGVHD outside clinical trials.