The use of defibrotide in blood and marrow transplantation

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

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. This study aimed to validate the accuracy of VODCheck as a prognostic test for VOD/SOS in an independent cohort of patients. 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). 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. 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.

Defibrotide improves COVID-19-related acute respiratory distress syndrome in myeloma patients after chimeric antigen receptor T-cell treatment without compromising virus-specific and anti-myeloma T-cell responses

Not available.

The critical role of endothelial cell in the toxicity associated with chimeric antigen receptor T cell therapy and intervention strategies

Chimeric antigen receptor (CAR)-T cell therapy has shown promising results in patients with hematological malignancies. However, many patients still have poor prognoses or even fatal outcomes due to the life-threatening toxicities associated with the therapy. Moreover, even after improving the known influencing factors (such as number or type of CAR-T infusion) related to CAR-T cell infusion, the results remain unsatisfactory. In recent years, it has been found that endothelial cells (ECs), which are key components of the organization, play a crucial role in various aspects of immune system activation and inflammatory response. The levels of typical markers of endothelial activation positively correlated with the severity of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxic syndrome (ICANS), suggesting that ECs are important targets for intervention and toxicity prevention. This review focuses on the critical role of ECs in CRS and ICANS and the intervention strategies adopted.

Hepatic veno-occlusive disease complicated with extreme hyperammonaemia (920 µmol/L) treated with defibrotide, lactulose, rifampin and haemodialysis

Hepatic veno-occlusive disease (VOD)/sinusoidal obstructive syndrome (SOS) is a severe complication that can occur following haematopoietic stem cell transplant (HSCT) with high-intensity conditioning chemotherapy regimens. Severe VOD/SOS, often characterised by multiorgan failure, is associated with a high mortality rate. This case report details the complex clinical course of a male patient in his mid-20s, recently diagnosed with B cell acute lymphoblastic leukaemia, who underwent allogeneic HSCT. Based on the 2023 European Society for Blood and Marrow Transplantation (EBMT) criteria, the patient developed very severe VOD/SOS, prompting immediate treatment with defibrotide. Unexpectedly, he developed profound hyperammonaemia exceeding 900 µmol/L, leading to encephalopathy and cerebral oedema. Despite aggressive interventions including defibrotide, lactulose, rifampin and haemodialysis, the patient passed away due to cerebral oedema and pulseless electrical activity arrest. We theorise the hyperammonaemia is disproportionate to his hepatic dysfunction and is possibly secondary to an acquired defect of the urea synthesis consistent with idiopathic hyperammonaemia, a rare complication in patients receiving intense conditioning chemotherapy.

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 activation and damage as a common pathological substrate in different pathologies and cell therapy complications

The endothelium is a biologically active interface with multiple functions, some of them common throughout the vascular tree, and others that depend on its anatomical location. Endothelial cells are continually exposed to cellular and humoral factors, and to all those elements (biological, chemical, or hemodynamic) that circulate in blood at a certain time. It can adapt to different stimuli but this capability may be lost if the stimuli are strong enough and/or persistent in time. If the endothelium loses its adaptability it may become dysfunctional, becoming a potential real danger to the host. Endothelial dysfunction is present in multiple clinical conditions, such as chronic kidney disease, obesity, major depression, pregnancy-related complications, septic syndromes, COVID-19, and thrombotic microangiopathies, among other pathologies, but also in association with cell therapies, such as hematopoietic stem cell transplantation and treatment with chimeric antigen receptor T cells. In these diverse conditions, evidence suggests that the presence and severity of endothelial dysfunction correlate with the severity of the associated disease. More importantly, endothelial dysfunction has a strong diagnostic and prognostic value for the development of critical complications that, although may differ according to the underlying disease, have a vascular background in common. Our multidisciplinary team of women has devoted many years to exploring the role of the endothelium in association with the mentioned diseases and conditions. Our research group has characterized some of the mechanisms and also proposed biomarkers of endothelial damage. A better knowledge would provide therapeutic strategies either to prevent or to treat endothelial dysfunction.

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.

Defibrotide modulates pulmonary endothelial cell activation and protects against lung inflammation in pre-clinical models of LPS-induced lung injury and idiopathic pneumonia syndrome

Introduction

A multiple organ dysfunction syndrome (MODS) workshop convened by the National Institute of Child Health and Human Development in 2015 identified acute respiratory distress syndrome (ARDS) and complications of allogeneic blood and marrow transplantation (allo-BMT) as contributors to MODS in pediatric patients. Pulmonary dysfunction also remains a significant complication of allo-BMT. Idiopathic pneumonia syndrome (IPS) defines non-infectious, acute, lung injury that occurs post-transplant. Injury and activation to endothelial cells (ECs) contribute to each form of lung inflammation.

Methods

Two murine models were employed. In an ARDS model, naïve B6 mice receive an intravenous (i.v.) injection of lipopolysaccharide (LPS). In the established model of IPS, naïve B6D2F1 mice receive lethal total body irradiation followed by BMT from either allogeneic (B6) or syngeneic (B6D2F1) donors. Lung inflammation was subsequently assessed in each scenario.

Results

Intravenous injection of LPS to B6 mice resulted in enhanced mRNA expression of TNFα, IL-6, Ang-2, E-, and P-selectin in whole lung homogenates. The expression of Ang-2 in this context is regulated in part by TNFα. Additionally, EC activation was associated with increased total protein and cellularity in broncho-alveolar lavage fluid (BALF). Similar findings were noted during the development of experimental IPS. We hypothesized that interventions maintaining EC integrity would reduce the severity of ARDS and IPS. Defibrotide (DF) is FDA approved for the treatment of BMT patients with sinusoidal obstruction syndrome and renal or pulmonary dysfunction. DF stabilizes activated ECs and protect them from further injury. Intravenous administration of DF before and after LPS injection significantly reduced mRNA expression of TNFα, IL6, Ang-2, E-, and P-selectin compared to controls. BALF showed decreased cellularity, reflecting less EC damage and leak. Allogeneic BMT mice were treated from day -1 through day 14 with DF intraperitoneally, and lungs were harvested at 3 weeks. Compared to controls, DF treatment reduced mRNA expression of TNFα, IL6, Ang-2, E-, and P- selectin, BALF cellularity, and lung histopathology.

Conclusion

The administration of DF modulates EC injury in models of ARDS and IPS. Cytokine inhibition in combination with agents that stabilize EC integrity may be an attractive strategy for patients in each setting.

Defibrotide plus best standard of care compared with best standard of care alone for the prevention of sinusoidal obstruction syndrome (HARMONY): a randomised, multicentre, phase 3 trial

BACKGROUND

Sinusoidal obstruction syndrome, also known as veno-occlusive disease, is a potentially life-threatening complication of haematopoietic stem-cell transplantation (HSCT). We aimed to compare defibrotide prophylaxis plus best supportive care versus best supportive care alone for sinusoidal obstruction syndrome prevention after HSCT.

METHODS

This open-label, randomised, multicentre, phase 3 trial was done in 104 centres in 14 countries. Patients who were at least 1 month old, were scheduled to receive allogeneic HSCT (adult [aged >16 years] or paediatric [aged >1 month to ≤16 years] patients) or autologous HSCT (paediatric patients only), and were at high risk or very high risk of developing sinusoidal obstruction syndrome were eligible for inclusion. Patients were randomly assigned (1:1) by an interactive web response system to receive intravenous defibrotide 25 mg/kg per day (four equal doses [6·25 mg/kg per dose]) and best supportive care (determined by individual institutional guidelines; defibrotide prophylaxis group) or best supportive care only (best supportive care group). Randomisation was stratified by sinusoidal obstruction syndrome risk, age, and country. The primary endpoint, sinusoidal obstruction syndrome-free survival at day 30 after HSCT, was assessed by an independent Endpoint Adjudication Committee in the intention-to-treat (ITT) population. Safety was assessed in all patients who received protocol treatment. The trial is registered with ClinicalTrials.gov, NCT02851407.

FINDINGS

Between Jan 11, 2017, and Oct 20, 2020, 372 patients (172 [46%] women and 200 [54%] men; median age 14·0 years [IQR 4·0-41·0] were randomly assigned to the defibrotide prophylaxis group (n=190) or best supportive care group (n=182; ITT population). On the basis of recommendations from the Independent Data Monitoring Committee following completion of the planned interim analysis in the first 280 recruited patients on April 29, 2020, enrolment was prematurely stopped for presumed futility. At the final analysis, sinusoidal obstruction syndrome-free survival by day 30 after HSCT was 67% (95% CI 58-74) in the defibrotide prophylaxis group and 73% (62-80) in the best supportive care group (HR 1·27 [95% CI 0·84-1·93]; p=0·85). Treatment-emergent adverse events were similar between groups during the randomised prophylaxis phase; most treatment-emergent adverse events were related to the transplantation rather than to study drug. The most common grade 3 or 4 treatment-emergent adverse events were stomatitis (grade 3, 52 [29%] of 181 patients in the defibrotide prophylaxis group and 56 [32%] of 174 patients in the best supportive care group; grade 4, two [1%] in the defibrotide prophylaxis group and two [1%] in the best supportive care group) and febrile neutropaenia (grade 3, 51 [28%] in the defibrotide prophylaxis group and 52 [30%] in the best supportive care group; grade 4, no patients in the defibrotide prophylaxis group and three [2%] in the best supportive care group). Serious treatment-emergent adverse events occurred in 74 (41%) of 181 patients in the defibrotide prophylaxis group and 61 (35%) of 174 patients in the best supportive care group. In the rescue phase, when patients in both treatment groups received defibrotide as rescue treatment, fatal treatment-related adverse events occurred in one (4%) of 25 patients in the defibrotide prophylaxis group (intracranial haemorrhage) and one (3%) of 31 patients in the best supportive care group (sinusoidal obstruction syndrome).

INTERPRETATION

Defibrotide did not show a benefit in the prophylaxis of sinusoidal obstruction syndrome. Additional studies of carefully selected patients at high risk of sinusoidal obstruction syndrome after HSCT are warranted.

FUNDING

Jazz Pharmaceuticals.

Characterization of the endotheliopathy, innate-immune activation and hemostatic imbalance underlying CAR-T cell toxicities: laboratory tools for an early and differential diagnosis

BACKGROUND

Chimeric antigen receptor (CAR)-T cell-based immunotherapy constitutes a revolutionary advance for treatment of relapsed/refractory hematological malignancies. Nevertheless, cytokine release and immune effector cell-associated neurotoxicity syndromes are life-threatening toxicities in which the endothelium could be a pathophysiological substrate. Furthermore, differential diagnosis from sepsis, highly incident in these patients, is challenging. Suitable laboratory tools could be determinant for their appropriate management.

METHODS

Sixty-two patients treated with CAR-T cell immunotherapy for hematological malignancies (n=46 with CD19-positive diseases, n=16 with multiple myeloma) were included. Plasma samples were obtained: before CAR-T cell infusion (baseline); after 24-48 hours; at suspicion of any toxicity onset and 24-48 hours after immunomodulatory treatment. Biomarkers of endothelial dysfunction (soluble vascular cell adhesion molecule 1 (sVCAM-1), soluble TNF receptor 1 (sTNFRI), thrombomodulin (TM), soluble suppression of tumorigenesis-2 factor (ST2), angiopoietin-2 (Ang-2)), innate immunity activation (neutrophil extracellular traps (NETs), soluble C5b-9 (sC5b-9)) and hemostasis/fibrinolysis (von Willebrand Factor antigen (VWF:Ag), ADAMTS-13 (A13), α2-antiplasmin (α2-AP), plasminogen activator inhibitor-1 antigen (PAI-1 Ag)) were measured and compared with those in cohorts of patients with sepsis and healthy donors.

RESULTS

Patients who developed CAR-T cell toxicities presented increased levels of sVCAM-1, sTNFRI and ST2 at the clinical onset versus postinfusion values. Twenty-four hours after infusion, ST2 levels were good predictors of any CAR-T cell toxicity, and combination of ST2, Ang-2 and NETs differentiated patients requiring intensive care unit admission from those with milder clinical presentations. Association of Ang-2, NETs, sC5b-9, VWF:Ag and PAI-1 Ag showed excellent discrimination between severe CAR-T cell toxicities and sepsis.

CONCLUSIONS

This study provides relevant contributions to the current knowledge of the CAR-T cell toxicities pathophysiology. Markers of endotheliopathy, innate immunity activation and hemostatic imbalance appear as potential laboratory tools for their prediction, severity and differential diagnosis.

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 (5 μg/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.

Hepatobiliary disease after bone marrow transplant

INTRODUCTION

Bone marrow transplantation (BMT) is the standard treatment for several hematologic pathologies. Post-BMT patients may develop hepatobiliary complications that impact morbidity and mortality. The differential diagnosis may include drug-induced liver injury (DILI), sepsis-associated liver injury (SALI), sinusoidal obstruction syndrome (SOS), graft-versus-host disease (GVHD), viral hepatitis, ischemic and fulminant hepatitis, among others.

AREA COVERED

Defining the etiology of hepatobiliary injury is challenging due to the overlapping symptoms. Thus, it is necessary to be aware of and understand the clinical characteristics of these hepatobiliary complications and provide adequate management with possible better outcomes. We reviewed the scientific literature focused on early hepatobiliary complications associated with BMT. We searched the PubMed database using the following descriptors: hepatic complications, drug-induced liver disease, graft-versus-host disease, cholestasis, sepsis, sinusoidal obstruction syndrome, cytomegalovirus, viral hepatitis, bone marrow transplantation, and hematopoietic stem cell transplantation.

EXPERT OPINION

Post-BMT hepatobiliary complications comprise several differential diagnoses and are challenges for the hepatologist's clinical practice. When evaluating these patients, it is necessary to consider the temporality between the use of certain medications, the increase in liver enzymes, and the presence of infection, in addition to applying diagnostic criteria and complementary tests for a specific diagnosis.

The Importance of New EBMT Criteria on the Diagnosis of Veno-Occlusive Liver Disease in Children

BACKGROUND

Early recognition and specific therapy facilitate a favorable disease course in hepatic venous-occlusive disease (HVOD) following hematopoietic stem cell transplantation (HCT). Diagnostic and classification criteria, published by the European Society for Blood and Marrow Transplantation (EBMT), better account for clinical differences in disease presentation in pediatric populations.

OBJECTIVES

To compare the course of HVOD in children before and after the implementation of new EBMT criteria.

MATERIAL AND METHODS

The study retrospectively evaluates 26 HVODs in 179 children treated in a single HCT unit (Slovakia) comparing the period of 2014-2017 using the Baltimore and modified Seattle criteria with the period of 2018-2021, when new EBMT criteria were adopted.

RESULTS

No difference in HVOD incidence (11.2% vs. 14.8%, p = 0.46) and in time of diagnosis post-HCT (15.6 days vs. 15.7 days, p = 0.75) was found. With EBMT criteria we observed more frequent anicteric disease at diagnosis (50% vs. 87.5%, p = 0.04), lower serum bilirubin at diagnosis (3.4 mg/dL vs. 1.23 mg/dL, p = 0.045), and non-significant trends of shorter defibrotide treatment (21.7 days vs. 15.6 days, p = 0.73), decreased mortality (30% vs. 6.2%, p = 0.10) and shorter hospitalization (73.1 days vs. 59.6 days, p = 0.54).

CONCLUSIONS

Different time periods around the implementation of new criteria are evaluated, underling that pediatric EBMT criteria for post-transplant HVOD diagnosis appear more sensitive.

Early diagnostic value of liver stiffness measurement in hepatic sinusoidal obstruction syndrome induced by hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT)-sinusoidal obstruction syndrome (SOS), also known as veno-occlusive disease, is a clinical syndrome characterized by symptoms, such as right upper quadrant pain, jaundice, fluid retention, and hepatomegaly, and is caused by pre-treatment-related hepatotoxicity during the early stages after HSCT. Clinical diagnosis of HSCT-SOS is based on the revised Seattle or Baltimore standards. The revised standard by the European Society for Bone Marrow Transplantation in 2016 has good practicability and can be used in combination with these two standards. Eight studies have shown the value of liver stiffness measurement (LSM) in the early diagnosis of HSCT-SOS. Four studies investigated LSM specificity and sensitivity for the early diagnosis of HSCT-SOS. LSM can distinguish SOS from other post-HSCT complications, enabling a clear differential diagnosis. It has been shown that median LSM of patients with SOS is significantly higher than that of patients with other treatment-related liver complications (e.g., acute cholecystitis, cholangitis, antifungal drug-related liver injury, liver graft-versus-host disease, isolated liver biochemical changes, and fulminant Epstein Barr virus related hepatitis reactivation). Therefore, the above data confirmed the utility of LSM and strongly suggested that LSM improves the positive predictive value of the SOS diagnostic clinical score after allogeneic HSCT. Early diagnosis of SOS is beneficial in preventing severe HSCT complications.

Defibrotide suppresses brain metastasis by activating the adenosine A2A receptors

Brain metastasis is a devastating clinical condition globally as one of the most common central nervous system malignancies. The current study aimed to assess the effect of defibrotide, an Food and Drug Administration-approved drug, against brain metastasis and the underlying molecular mechanisms. Two tumor cell lines with high brain metastasis potential, PC-9 and 231-BR, were subjected to defibrotide treatment of increasing dosage. The metastasis capacity of the tumor cells was evaluated by cell invasion and migration assays. Western blotting was employed to determine the levels of tight junction proteins in the blood-brain barrier (BBB) including Occludin, Zo-1, and Claudin-5, as well as metastasis-related proteins including CXCR4, MMP-2, and MMP-9. The in-vitro observations were further verified in nude mice, by monitoring the growth of xenograft tumors, mouse survival and brain metastasis foci following defibrotide treatment. Defibrotide inhibited proliferation, migration, invasion, and promotes lactate dehydrogenase release of brain metastatic tumor cells, elevated the levels of BBB tight junction proteins and metastasis-related proteins. Such beneficial role of defibrotide was mediated by its inhibitory action on the SDF-1/CXCR4 signaling axis both in vitro and in vivo, as CXCR4 agonist SDF1α negated the anti-tumoral effect of defibrotide on mouse xenograft tumor growth, mouse survival and brain metastasis. Defibrotide inhibits brain metastasis through activating the adenosine A2A receptors, which in turn inhibits the SDF-1/CXCR4 signaling axis. Our study hereby proposes defibrotide as a new and promising candidate drug against brain metastasis of multiple organ origins.

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.

Therapeutic Plasma Exchange in Pediatric Patients With Sinusoidal Obstruction Syndrome/Veno-Occlusive Disease After Hematopoietic Stem Cell Transplantation: A Single-Center Experience

OBJECTIVES

Sinusoidal obstruction syndrome/venoocclusive disease is a significant complication of hematopoietic stem cell transplantation. Due to high mortality rates, new treatment strategies have been investigated. Here, we have presented outcomes of therapeutic plasma exchange performed on patients with sinusoidal obstruction syndrome/veno-occlusive disease.

MATERIAL AND METHODS

Our study included 70 pediatric patients diagnosed with sinusoidal obstruction syndrome/veno-occlusive disease. Therapeutic plasma exchange procedures in patients were evaluated retrospectively.

RESULTS

There were 9 mild (12.9%), 9 moderate (12.9%), 21 severe (30%), and 31 very severe (44.2%) cases of sinusoidal obstruction syndrome/venoocclusive disease. Therapeutic plasma exchange was performed in 31 of the 70 study patients (59.6%). Moreover, 10/21 patients with severe (47.6%) and 21/31 patients with very severe (67.7%) disease underwent plasma exchange. Mean time from diagnosis of sinusoidal obstruction syndrome/venoocclusive disease to therapeutic plasma exchange initiation was 2.3 days. The 31 patients who received therapeutic plasma exchange had a total of 146 sessions. Overall survival rates at 100 days were 87.1% and 92.3% for patients who did and did not undergo therapeutic plasma exchange, respectively. When patients with mild and moderate disease who were not expected to undergo plasma exchange were excluded (n = 52), 100-day overall survival rates were 87.1% and 90.5% for those who did and did not undergo plasma exchange, respectively. When we compared severe versus very severe groups, no significant difference was found.

CONCLUSIONS

Plasmapheresis had no positive effect on survival. However, overall survival in all groups was higher than that in the literature, despite the high number of patients with severe and very severe disease. Interpretation of the results is limited by the retrospective nature of the study. Thus, prospective, randomized controlled trials with larger numbers of patients are necessary to investigate the role of therapeutic plasma exchange in patients with sinusoidal obstruction syndrome/veno-occlusive disease.

A Systematic Review and Meta-Analysis of Studies of Defibrotide Prophylaxis for Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome

Background and Objectives

Defibrotide is approved to treat severe veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) after haematopoietic cell transplantation in patients aged > 1 month in the European Union and for VOD/SOS with renal/pulmonary dysfunction post-haematopoietic cell transplantation in the United States. This meta-analysis estimated the incidence and risk of VOD/SOS after intravenous defibrotide prophylaxis using the published literature.

Methods

PubMed, Embase and Web of Science were searched through 30 November 2021 for defibrotide studies in VOD/SOS “prevention” or “prophylaxis,” excluding phase I studies, case reports, studies with fewer than ten patients and reviews.

Results

The search identified 733 records; 24 met inclusion criteria, of which 20 (N = 3005) evaluated intravenous defibrotide for VOD/SOS prophylaxis. Overall VOD/SOS incidence with intravenous defibrotide was 5%, with incidences of 5% in adults and 8% in paediatric patients. In eight studies with data on intravenous defibrotide prophylaxis vs controls (e.g. heparin, no prophylaxis), VOD/SOS incidence in controls was 16%. The risk ratio for developing VOD/SOS with defibrotide prophylaxis vs controls was 0.30 (95% confidence interval 0.12–0.71; p = 0.006).

Conclusions

This analysis suggests a low incidence of VOD/SOS following intravenous defibrotide prophylaxis, regardless of age group, and a lower relative risk for VOD/SOS with defibrotide prophylaxis vs controls in patient populations at high risk of VOD/SOS.

Retrospective Application of Sinusoidal Obstruction Syndrome/Veno-occlusive Disease Diagnostic Criteria in a Pediatric Hematopoietic Stem Cell Transplant Cohort

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) posthematopoietic stem cell transplantation (HSCT) is often diagnosed using the modified Seattle (MS) or European Society for Blood and Marrow Transplantation (EBMT) criteria. We hypothesized that strict application of these criteria could affect the timing of diagnosis and incidence of SOS/VOD. We collected data on 215 transplants performed in 184 patients at a single pediatric hematopoietic stem cell transplantation center, which were divided into 3 cohorts. Clinical diagnosis and treatment of SOS/VOD was documented in 13% of transplants (cohort 1). On retrospective review, 49% of transplant events met either MS and/or EBMT criteria, however, were not diagnosed with SOS/VOD (cohort 2); remaining 38% of transplant events did not meet MS or EBMT criteria and were not diagnosed with SOS/VOD (cohort 3). Day+100 overall survival was significantly inferior for cohort 1 (78%) compared with cohorts 2 or 3 (92% and 95%, P=0.01) with no difference between cohorts 2 and 3 (P=0.5). Patients diagnosed with SOS/VOD >day+13 had worse day+100 overall survival when compared with those diagnosed ≤day13 (64.3% and 100%, respectively, P=0.02). This study highlights the value of careful clinical assessment to guide diagnosis and the need to refine diagnostic criteria for SOS/VOD in children.

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.

Is the Endothelium the Missing Link in the Pathophysiology and Treatment of COVID-19 Complications?

Patients with COVID-19 present a wide spectrum of disease severity, from asymptomatic cases in the majority to serious disease leading to critical care and even death. Clinically, four different scenarios occur within the typical disease timeline: first, an incubation and asymptomatic period; second, a stage with mild symptoms due mainly to the virus itself; third, in up to 20% of the patients, a stage with severe symptoms where a hyperinflammatory response with a cytokine storm driven by host immunity induces acute respiratory distress syndrome; and finally, a post-acute sequelae (PASC) phase, which present symptoms that can range from mild or annoying to actually quite incapacitating. Although the most common manifestation is acute respiratory failure of the lungs, other organs are also frequently involved. The clinical manifestations of the COVID-19 infection support a key role for endothelial dysfunction in the pathobiology of this condition. The virus enters into the organism via its interaction with angiotensin-converting enzyme 2-receptor that is present prominently in the alveoli, but also in endothelial cells, which can be directly infected by the virus. Cytokine release syndrome can also drive endothelial damage independently. Consequently, a distinctive feature of SARS-CoV-2 infection is vascular harm, with severe endothelial injury, widespread thrombosis, microangiopathy, and neo-angiogenesis in response to endothelial damage. Therefore, endothelial dysfunction seems to be the pathophysiological substrate for severe COVID-19 complications. Biomarkers of endothelial injury could constitute strong indicators of disease progression and severity. In addition, the endothelium could represent a very attractive target to both prevent and treat these complications. To establish an adequate therapy, the underlying pathophysiology and corresponding clinical stage should be clearly identified. In this review, the clinical features of COVID-19, the central role of the endothelium in COVID-19 and in other pathologies, and the potential of specific therapies aimed at protecting the endothelium in COVID-19 patients are addressed.

Distinctive Biomarker Features in the Endotheliopathy of COVID-19 and Septic Syndromes

BACKGROUND

Endotheliopathy is a key element in COVID-19 pathophysiology, contributing to both morbidity and mortality. Biomarkers distinguishing different COVID-19 phenotypes from sepsis syndrome remain poorly understood.

OBJECTIVE

To characterize circulating biomarkers of endothelial damage in different COVID-19 clinical disease stages compared with sepsis syndrome and normal volunteers.

METHODS

Patients with COVID-19 pneumonia (n = 49) were classified into moderate, severe, or critical (life-threatening) disease. Plasma samples were collected within 48 to 72 h of hospitalization to analyze endothelial activation markers, including soluble Vascular Cell Adhesion Molecule-1 (sVCAM-1), von Willebrand Factor (VWF), A disintegrin-like and metalloprotease with thrombospondin type 1 motif no. 13 (ADAMTS-13) activity, thrombomodulin (TM), and soluble TNF receptor I (sTNFRI); heparan sulfate (HS) for endothelial glycocalyx degradation; C5b9 deposits on endothelial cells in culture and soluble C5b9 for complement activation; circulating dsDNA for neutrophil extracellular traps (NETs) presence, and α2-antiplasmin and PAI-1 as parameters of fibrinolysis. We compared the level of each biomarker in all three COVID-19 groups and healthy donors as controls (n = 45). Results in critically ill COVID-19 patients were compared with other intensive care unit (ICU) patients with septic shock (SS, n = 14), sepsis (S, n = 7), and noninfectious systemic inflammatory response syndrome (NI-SIRS, n = 7).

RESULTS

All analyzed biomarkers were increased in COVID-19 patients versus controls (P < 0.001), except for ADAMTS-13 activity that was normal in both groups. The increased expression of sVCAM-1, VWF, sTNFRI, and HS was related to COVID-19 disease severity (P < 0.05). Several differences in these parameters were found between ICU groups: SS patients showed significantly higher levels of VWF, TM, sTNFRI, and NETS compared with critical COVID-19 patients and ADAMTS-13 activity was significantly lover in SS, S, and NI-SIRS versus critical COVID-19 (P < 0.001). Furthermore, α2-antiplasmin activity was higher in critical COVID-19 versus NI-SIRS (P < 0.01) and SS (P < 0.001), whereas PAI-1 levels were significantly lower in COVID-19 patients compared with NI-SIRS, S, and SS patients (P < 0.01).

CONCLUSIONS

COVID-19 patients present with increased circulating endothelial stress products, complement activation, and fibrinolytic dysregulation, associated with disease severity. COVID-19 endotheliopathy differs from SS, in which endothelial damage is also a critical feature of pathobiology. These biomarkers could help to stratify the severity of COVID-19 disease and may also provide information to guide specific therapeutic strategies to mitigate endotheliopathy progression.

Early vascular endothelial complications after hematopoietic cell transplantation: Role of the endotheliopathy in biomarkers and target therapies development

This work aims to review the role of endothelial dysfunction underlying the main complications appearing early after autologous and allogeneic hematopoietic cell transplantation (HCT). The endothelial damage as the pathophysiological substrate of sinusoidal obstruction syndrome (SOS) is well established. However, there is growing evidence of the involvement of endothelial dysfunction in other complications, such as acute graft-versus-host disease (aGVHD) and transplant-associated thrombotic microangiopathy (TA-TMAs). Moreover, HCT-related endotheliopathy is not only limited to the HCT setting, as there is increasing evidence of its implication in complications derived from other cellular therapies. We also review the incidence and the risk factors of the main HCT complications and the biological evidence of the endothelial involvement and other linked pathways in their development. In addition, we cover the state of the art regarding the potential use of the biomarkers of endotheliopathy in the prediction, the early diagnosis, and the follow-up of the HCT complications and summarize current knowledge points to the endothelium and the other linked pathways described as potential targets for the prevention and treatment of HCT-complications. Lastly, the endothelium-focused therapeutic strategies that are emerging and might have a potential impact on the survival and quality of life of post-HCT-patients are additionally reviewed.

Influence of creatinine levels on survival in patients with veno-occlusive disease treated with defibrotide

BACKGROUND/AIMS

Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is one of the most fatal complications of hematopoietic cell transplantation (HCT), and defibrotide is the only curative drug. We conducted this study to confirm the survival rate of VOD/SOS patients diagnosed in Korea and assess the efficacy of defibrotide.

METHODS

Patients diagnosed with VOD/SOS after allogenic HCT between 2003 and 2020 were enrolled. We investigated day +100 survival rates and associated risk factors in patients who satisfied the modified Seattle criteria within 50 days of HCT.

RESULTS

A total of 110 patients satisfied the modified Seattle criteria, of which 65.5% satisfied the Baltimore criteria. Thirty-seven patients were treated with defibrotide. The day +100 survival rate of the 110 patients was 65.3%. The survival rates in patients who did not meet the Baltimore criteria and in those who did were 86.8% and 53.7%, respectively (p = 0.001). The day +100 survival rate of patients treated with defibrotide was 50.5%. Among the patients receiving defibrotide, those whose creatinine levels were more than 1.2 times the baseline had a significantly lower survival rate at 26.7% (p = 0.014). On multivariate regression analysis, the hazard ratio of satisfaction of the Baltimore criteria was 4.54 (95% confidence interval [CI], 1.69 to 12.21; p = 0.003). In patients treated with defibrotide, the hazard ratio was 8.70 (95% CI, 2.26 to 33.45; p = 0.002), when creatinine was more than 1.2 times the baseline on administration.

CONCLUSION

The day +100 survival rate was significantly lower when the Baltimore criteria were satisfied, and when there was an increase in creatinine at the time of defibrotide administration.

Hepatic sinusoidal obstruction syndrome/veno-occlusive disease after hematopoietic cell transplantation: historical and current considerations in Korea

Hepatic sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) is a rare but severe complication of hematopoietic cell transplantation (HCT) showing high mortality. Multiple risk factors for SOS/VOD were identified, but it is often confused with other hepatic complications due to nonspecific clinical features. Therefore, diagnostic and severity criteria have been revised several times. The European Society of Blood and Marrow Transplantation suggested a new guideline that excludes the standard duration of development within 21 days, emphasizes late-onset SOS/VOD, and suggests the importance of Doppler ultrasonography. The severity criteria were further subdivided for guidance to begin active treatment using defibrotide which was approved in Korea since 2016. In a phase 3 trial, defibrotide had superior 100-day survival, compared to best available treatments (38.2% vs. 25.0%). Although several studies of SOS/VOD in Korean patients have been performed after the implementation of HCT, most involved small number of pediatric patients. Recently, the Korean Society of Blood and Marrow Transplantation investigated the incidence of SOS/VOD in the Korean population, and several influential studies of adult patients were published. Here, we summarize recent issues regarding the mechanism, diagnosis, severity criteria, prevention, and treatments of SOS/VOD in Korean patients, as well as recent analyses of nationwide incidence.

The importance of endothelial protection: the emerging role of defibrotide in reversing endothelial injury and its sequelae

Hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS), a potentially life-threatening complication of hematopoietic cell transplantation (HCT), results from prolonged sinusoidal endothelial cell activation and profound endothelial cell damage, with sequelae. Defibrotide, the only drug approved in the United States and Europe for treating VOD/SOS post-HCT, has European Commission orphan drug designation for preventing graft-versus-host disease (GvHD), associated with endothelial dysfunction. This endothelial cell protector and stabilizing agent restores thrombo-fibrinolytic balance and preserves endothelial homeostasis through antithrombotic, fibrinolytic, anti-inflammatory, anti-oxidative, and anti-adhesive activity. Defibrotide also preserves endothelial cell structure by inhibiting heparanase activity. Evidence suggests that downregulating p38 mitogen-activated protein kinase (MAPK) and histone deacetylases (HDACs) is key to defibrotide’s endothelial protective effects; phosphatidylinositol 3-kinase/Akt (PI3K/AKT) potentially links defibrotide interaction with the endothelial cell membrane and downstream effects. Despite defibrotide’s being most extensively studied in VOD/SOS, emerging preclinical and clinical data support defibrotide for treating or preventing other conditions driven by endothelial cell activation, dysfunction, and/or damage, such as GvHD, transplant-associated thrombotic microangiopathy, or chimeric antigen receptor T-cell (CAR-T) therapy-associated neurotoxicity, underpinned by cytokine release syndrome and endotheliitis. Further preclinical and clinical studies will explore defibrotide’s potential utility in a broader range of disorders resulting from endothelial cell activation and dysfunction.

Progressive endothelial cell damage in correlation with sepsis severity. Defibrotide as a contender

BACKGROUND

The vascular endothelium plays a key role in sepsis pathophysiology and the associated organ dysfunction.

METHODS

We evaluated endothelial function in an experimental in vitro model of sepsis, using endothelial cells grown in the presence of serum from patients with septic syndromes (sepsis, severe sepsis, and septic shock), noninfectious systemic inflammatory response syndrome (NI-SIRS) and healthy volunteers. Experiments were performed in the absence and presence of defibrotide (DF) (100 µg/ml) to evaluate its potential protective effect.

RESULTS

After exposure to patients' sera, there was a progressive endothelial cell activation in correlation with sepsis severity, with a proinflammatory and prothrombotic phenotype, exhibiting significantly increased expression of adhesion receptors at the surface (intercellular adhesion molecule-1, p < .05 and vascular cell adhesion molecule-1, p < .05); higher production and release to the extracellular matrix (ECM) of von Willebrand factor (p < .001); augmented thrombogenicity of the ECM toward platelets (p < .001); and increased phosphorylation of intracellular p38MAPK. DF prevented these changes in all groups.

CONCLUSIONS

Markers of endothelial damage increased progressively in association with the severity of septic syndromes. The endothelium is therefore an important therapeutic target to prevent complications of sepsis. DF shows promising potential to modulate the endothelial damage associated with sepsis and may constitute a pharmacological tool to decrease its sequelae including multiorgan failure.

Defibrotide: potential for treating endothelial dysfunction related to viral and post-infectious syndromes

INTRODUCTION

Defibrotide (DF) is a polyribonucleotide with antithrombotic, pro-fibrinolytic, and anti-inflammatory effects on endothelium. These effects and the established safety of DF present DF as a strong candidate to treat viral and post-infectious syndromes involving endothelial dysfunction.

AREAS COVERED

We discuss DF and other therapeutic agents that have the potential to target endothelial components of pathogenesis in viral and post-infectious syndromes. We introduce defibrotide (DF), describe its mechanisms of action, and explore its established pleiotropic effects on the endothelium. We describe the established pathophysiology of Coronavirus Disease 2019 (COVID-19) and highlight the processes specific to COVID-19 potentially modulated by DF. We also present influenza A and viral hemorrhagic fevers, especially those caused by hantavirus, Ebola virus, and dengue virus, as viral syndromes in which DF might serve therapeutic benefit. Finally, we offer our opinion on novel treatment strategies targeting endothelial dysfunction in viral infections and their severe manifestations.

EXPERT OPINION

Given the critical role of endothelial dysfunction in numerous infectious syndromes, in particular COVID-19, therapeutic pharmacology for these conditions should increasingly prioritize endothelial stabilization. Several agents with endothelial protective properties should be further studied as treatments for severe viral infections and vasculitides, especially where other therapeutic modalities have failed.

Biomarkers for Early Complications of Endothelial Origin After Allogeneic Hematopoietic Stem Cell Transplantation: Do They Have a Potential Clinical Role?

Endothelial cell (EC) dysfunction causes a number of early and life-threatening post hematopoietic stem cell transplant (HCT) complications that result in a rapid clinical decline. The main early complications are graft-vs.-host disease (GVHD), transplant associated thrombotic microangiopathy (TA-TMA), and sinusoidal obstruction syndrome (SOS). Post-HCT endothelial dysfunction occurs as a result of chemotherapy, infections, and allogeneic reactivity. Despite major advances in transplant immunology and improvements in supportive care medicine, these complications represent a major obstacle for successful HCT. In recent years, different biomarkers have been investigated for early detection of post-transplant endothelial cell dysfunction, but few have been validated. In this review we will define GVHD, TA-TMA and SOS, summarize the current data available in HCT biomarker research and identify promising biomarkers for detection and diagnosis of early HCT complications.

A Meta-Analysis Evaluating the Incidence of Bleeding Events With Intravenous Defibrotide Treatment Outside the Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome Setting

Defibrotide is approved to treat hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) with renal/pulmonary dysfunction following hematopoietic cell transplantation (HCT) in adult and pediatric patients in the United States, and to treat severe hepatic VOD/SOS post-HCT in adult and pediatric patients aged >1 month in the European Union. The defibrotide prescribing information warns that defibrotide may increase bleeding risk in VOD/SOS patients. To broaden our understanding of the incidence of bleeding with defibrotide, we performed a meta-analysis of the published literature of defibrotide use outside of the post-HCT VOD/SOS setting. Of 1857 records identified, 125 reported on defibrotide; 23 contained data on bleeding events. The estimated overall incidence of bleeding events was 1% (95% confidence interval [CI]: 0%-2%) and 8% (95% CI: 3%-14%) in studies using intravenous defibrotide and studies with controls, respectively. The risk ratio for bleeding events with intravenous defibrotide versus controls was 0.36 (95% CI: 0.24-0.52; P < .00001) among studies with data on intravenous defibrotide and controls. This meta-analysis of defibrotide use outside of the post-HCT VOD/SOS setting suggests that the incidence of bleeding with defibrotide is lower than controls.

GVHD Prophylaxis 2020

Graft-vs. host disease (GVHD), both acute and chronic are among the chief non-relapse complications of allogeneic transplantation which still cause substantial morbidity and mortality despite significant advances in supportive care over the last few decades. The prevention of GVHD therefore remains critical to the success of allogeneic transplantation. In this review we briefly discuss the pathophysiology and immunobiology of GVHD and the current standards in the field which remain centered around calcineurin inhibitors. We then discuss important translational advances in GVHD prophylaxis, approaching these various platforms from a mechanistic standpoint based on the pathophysiology of GVHD including in-vivo and ex-vivo T-cell depletion alongwith methods of selective T-cell depletion, modulation of T-cell co-stimulatory pathways (checkpoints), enhancing regulatory T-cells (Tregs), targeting T-cell trafficking as well as cytokine pathways. Finally we highlight exciting novel pre-clinical research that has the potential to translate to the clinic successfully. We approach these methods from a pathophysiology based perspective as well and touch upon strategies targeting the interaction between tissue damage induced antigens and T-cells, regimen related endothelial toxicity, T-cell co-stimulatory pathways and other T-cell modulatory approaches, T-cell trafficking, and cytokine pathways. We end this review with a critical discussion of existing data and novel therapies that may be transformative in the field in the near future as a comprehensive picture of GVHD prophylaxis in 2020. While calcineurin inhibitors remain the standard, post-transplant eparinsphamide originally developed to facilitate haploidentical transplantation is becoming an attractive alternative to traditional calcinuerin inhibitor based prophylaxis due to its ability to reduce severe forms of acute and chronic GVHD without compromising other outcomes, even in the HLA-matched setting. In addition T-cell modulation, particularly targeting some important T-cell co-stimulatory pathways have resulted in promising outcomes and may be a part of GVHD prophylaxis in the future. Novel approaches including targeting early events in GVHD pathogenesis such as interactions bvetween tissue damage associated antigens and T-cells, endothelial toxicity, and T-cell trafficking are also promising and discussed in this review. GVHD prophylaxis in 2020 continues to evolve with novel exicitng therapies on the horizon based on a more sophisticated understanding of the immunobiology of GVHD.

Incidence and risk factors of hepatic veno-occlusive disease/sinusoidal obstruction syndrome after allogeneic hematopoietic cell transplantation in adults with prophylactic ursodiol and intravenous heparin or prostaglandin E1

We attempted to identify the incidence and survival outcome of hepatic sinusoidal obstruction syndrome/veno-occlusive disease (VOD/SOS) after hematopoietic cell transplantation (HCT) under strategy of prophylactic ursodiol and intravenous heparin or prostaglandin E1 (PGE1). From 2009 to 2018, 2572 consecutive allogeneic-HCT cases were reviewed. We used oral ursodiol for all transplants, and most were administered low-dose heparin, while PGE1 in selected cases with low platelet count at the time of preconditioning. Diagnosis and severity grades were reassessed by revised EBMT criteria. The overall incidence of hepatic VOD/SOS was 3.4% (Mild 0.9%, Moderate 0.6%, Severe 0.7%, Very severe 1.2%) after allogeneic-HCT under strategy of intravenous prophylaxis. The 1-year overall survival of VOD/SOS was 41.4% which was divided into 73.9% for mild, 66.7% for moderate, 38.9% for severe, and 6.5% for very severe grade. Very high disease risk index, male gender, donor other than matched sibling donor, and busulfex > 9 mg/kg were affecting factors for development of VOD/SOS. For severe to very severe VOD/SOS, history of pre-HCT liver dysfunction was an additionally affecting factor. Allogeneic-HCT using ursodiol and intravenous prophylaxis was considered safe without significant bleeding complications and should be evaluated in future clinical trials. For those with high-risk of VOD/SOS, early intervention and management is important.

Pre-Exposure to Defibrotide Prevents Endothelial Cell Activation by Lipopolysaccharide: An Ingenuity Pathway Analysis

Defibrotide (DFB) effects on different endothelial cell pathways have been investigated focusing on a limited number of genes or molecules. This study explored the modulation of the gene expression profile of steady-state or lipopolysaccharide (LPS)-activated endothelial cells, following the DFB exposure. Starting from differentially regulated gene expression datasets, we utilized the Ingenuity Pathway Analysis (IPA) to infer novel information about the activity of this drug. We found that effects elicited by LPS deeply differ depending on cells were exposed to DFB and LPS at the same time, or if the DFB priming occurs before the LPS exposure. Only in the second case, we observed a significant down-regulation of various pathways activated by LPS. In IPA, the pathways most affected by DFB were leukocyte migration and activation, vasculogenesis, and inflammatory response. Furthermore, the activity of DFB seemed to be associated with the modulation of six key genes, including matrix-metalloproteinases 2 and 9, thrombin receptor, sphingosine-kinase1, alpha subunit of collagen XVIII, and endothelial-protein C receptor. Overall, our findings support a role for DFB in a wide range of diseases associated with an exaggerated inflammatory response of endothelial cells.

Insulin-like growth factor-I predicts sinusoidal obstruction syndrome following pediatric hematopoietic stem cell transplantation

Sinusoidal obstruction syndrome (SOS) is a potentially fatal complication of hematopoietic stem cell transplantation (HSCT) initiated through damage of sinusoidal endothelium and inflammation. Insulin-like growth factor-l (IGF-l) maintains and repairs endothelium and intestinal mucosa. We hypothesized that low IGF-l levels may increase the risk of inflammatory complications, such as SOS, in HSCT-patients. We prospectively measured IGF-l concentrations in 121 pediatric patients before, during, and after allogeneic HSCT. Overall, IGF-l levels were significantly reduced compared with healthy sex- and age-matched children. IGF-I levels pre-HSCT and at day 0 were inversely associated with C-reactive protein levels, hyperbilirubinemia, and number of platelet transfusions within the first 21 days post-transplant. Low levels of IGF-I before conditioning and at day of transplant were associated with increased risk of SOS diagnosed by the modified Seattle criteria (pre-HSCT: OR = 1.7 (95% CI: 1.2-2.6, p = 0.01), and the pediatric EBMT criteria (pre-HSCT: 1.7 (1.2-2.5, p = 0.009) and day 0: 1.7 (1.3-2.5, p = 0.001)/SDS decrease in IGF-1). These data suggest that IGF-I is protective against cytotoxic damage and SOS, most likely through trophic effects on endothelial cells and anti-inflammatory properties, and may prove useful as a predictive biomarker of SOS.

The protective effects of umbilical cord-derived endothelial colony forming cells on hepatic veno-occlusive disease

Hepatic veno-occlusive disease (HVOD) characterized by endothelial cell dysfunction is one of the serious complications after hematopoietic stem-cell transplantation or chemotherapeutic drug application. The mortality of HVOD patients with multiorgan dysfunction is as high as 80%. The primary aim of this study was to evaluate whether the infusion of human umbilical cord-derived endothelial colony forming cells (hUC-ECFCs) could mitigate HVOD injury and investigate the underlying mechanism. We found that the expression of chemokine C-X-C chemokine ligand 12 (CXCL12) was markedly increased in the livers of HVOD mice. Meanwhile, hUC-ECFCs infusion could significantly ameliorate liver injury in HVOD mice, which was accompanied by hUC-ECFCs recruitment in the liver, reduced liver pathological alterations, and decreased serum alanine aminotransferase and aspartate aminotransferase activity. Besides, CXCL12-induced migration in hUC-ECFCs was partly impeded by chemokine receptor type 7 (CXCR7) silence or CXCR4 blockage. In conclusion, our results demonstrated that hUC-ECFCs could mitigate HVOD through homing to the injured liver via the CXCL12-CXCR4/CXCR7 signaling pathway.

Imaging in Hepatic Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome

Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a potentially life-threatening complication of hematopoietic cell transplantation. Early diagnosis and, subsequently, earlier intervention have been shown to be beneficial to clinical outcomes. Diagnostic criteria from the European Society for Blood and Marrow Transplantation include recommendations on the use of imaging for diagnosis. This review discusses evidence on the use of imaging in the management of VOD/SOS and how imaging biomarkers can contribute to earlier diagnosis/treatment.

Endothelial cell function and endothelial-related disorders following haematopoietic cell transplantation

Use of haematopoietic cell transplantation (HCT) in the treatment of haematologic and neoplastic diseases may lead to life-threatening complications that cause substantial morbidity and mortality if untreated. In addition to patient- and disease-related factors, toxicity associated with HCT puts patients at risk for complications that share a similar pathophysiology involving endothelial cells (ECs). Normally, the endothelium plays a role in maintaining homeostasis, including regulation of coagulation, vascular tone, permeability and inflammatory processes. When activated, ECs acquire cellular features that may lead to phenotypic changes that induce procoagulant, pro-inflammatory and pro-apoptotic mediators leading to EC dysfunction and damage. Elevated levels of coagulation factors, cytokines and adhesion molecules are indicative of endothelial dysfunction, and endothelial damage may lead to clinical signs and symptoms of pathological post-HCT conditions, including veno-occlusive disease/sinusoidal obstruction syndrome, graft-versus-host disease, transplant-associated thrombotic microangiopathy and idiopathic pneumonia syndrome/diffuse alveolar haemorrhage. The endothelium represents a rational target for preventing and treating HCT complications arising from EC dysfunction and damage. Additionally, markers of endothelial damage may be useful in improving diagnosis of HCT-related complications and monitoring treatment effect. Continued research to effectively manage EC activation, injury and dysfunction may be important in improving patient outcomes after HCT.

Diagnosis and Treatment of VOD/SOS After Allogeneic Hematopoietic Stem Cell Transplantation

Hepatic veno-occlusive disease (VOD) or sinusoidal obstruction syndrome (SOS) is a rare complication characterized by hepatomegaly, right-upper quadrant pain, jaundice, and ascites, occurring after high-dose chemotherapy, hematopoietic stem cell transplantation (HSCT) and, less commonly, other conditions. We review pathogenesis, clinical appearance and diagnostic criteria, risk factors, prophylaxis, and treatment of the VOD occurring post-HSCT. The injury of the sinusoidal endothelial cells with loss of wall integrity and sinusoidal obstruction is the basis of development of postsinusoidal portal hypertension responsible for clinical syndrome. Risk factors associated with the onset of VOD and diagnostic tools have been recently updated both in the pediatric and adult settings and here are reported. Treatment includes supportive care, intensive management, and specific drug therapy with defibrotide. Because of its severity, particularly in VOD with associated multiorgan disease, prophylaxis approaches are under investigation. During the last years, decreased mortality associated to VOD/SOS has been reported being it attributable to a better intensive and multidisciplinary approach.

Extracellular Vesicles After Allogeneic Hematopoietic Cell Transplantation: Emerging Role in Post-Transplant Complications

Extracellular vesicles (EVs) play an important role in the cellular crosstalk by transferring bioactive molecules through biological barriers from a cell to another, thus influencing recipient cell functions and phenotype. Therefore, EVs are increasingly being explored as biomarkers of disease progression or response to therapy and as potential therapeutic agents in different contexts including in hematological malignancies. Recently, an EV role has emerged in allogeneic hematopoietic cell transplantation (allo-HCT) as well. Allogeneic hematopoietic cell transplantation often represents the only curative option in several hematological disorders, but it is associated with potentially life-threatening complications that can have a significant impact on clinical outcomes. The most common complications have been well-established and include graft-versus-host disease and infections. Furthermore, relapse remains an important cause of treatment failure. The aim of this review is to summarize the current knowledge, the potential applications, and clinical relevance of EVs in allo-HCT. Herein, we will mainly focus on the immune-modulating properties of EVs, in particular those derived from mesenchymal stromal cells, as potential therapeutic strategy to improve allo-HCT outcome. Moreover, we will briefly describe the main findings on EVs as biomarkers to monitor graft-versus-host disease onset and tumor relapse.

Diagnosis, grading, and treatment recommendations for children, adolescents, and young adults with sinusoidal obstructive syndrome: an international expert position statement

Sinusoidal obstructive syndrome, also known as hepatic veno-occlusive disease, is a potentially life-threatening complication that occurs in children undergoing haemopoietic stem-cell transplantation (HSCT). Differences in the incidence of genetic predisposition and clinical presentation of sinusoidal obstructive syndrome between children and adults have rendered the historical Baltimore and Seattle diagnostic criteria insufficient for children. In 2017, the European Society for Blood and Marrow Transplantation (EBMT) proposed the first paediatric diagnostic and severity grading guidelines for sinusoidal obstructive syndrome, intended for implementation across European centres. However, universally accepted paediatric criteria are needed to ensure prompt diagnosis, definitive treatment, and improved outcomes for children, adolescents, and young adults with sinusoidal obstructive syndrome, and to facilitate international clinical research collaboration. We convened an international panel of multidisciplinary experts including physicians with expertise in HSCT, paediatric intensive care, nephrology, hepatology, radiology, pathology, and transfusion medicine; HSCT advanced-practice providers and medical trainees; pharmacists; and translational and basic science researchers from the Pediatric Acute Lung Injury and Sepsis Investigators Network, the EBMT, the Pediatric Blood and Marrow Transplant Consortia, and several other institutions with extensive experience in sinusoidal obstructive syndrome. Panellists convened at The University of Texas, MD Anderson Cancer Center (Houston, TX, USA) in February, 2019, to evaluate the available evidence. In this expert position statement paper, we provide consensus recommendations for the international implementation of guidelines for the diagnosis, severity grading, and treatment of sinusoidal obstructive syndrome among children, adolescents, and young adults. We endorse universal adoption of paediatric diagnostic guidelines for sinusoidal obstruction syndrome as proposed by the EBMT, and provide implementation guidance for standardisation across centres; we have further proposed adjunctive use of age-appropriate organ-specific toxicity criteria for severity grading and provided prophylaxis and treatment considerations among children and adolescent and young adult patients. Key recommendations include: (1) liver biopsy, portal venous wedge pressure, and reversal of portal venous flow on Doppler ultrasonography should not be used for the routine diagnosis of sinusoidal obstructive syndrome in children, adolescents, and young adults; (2) platelet refractoriness can be defined as a corrected count increment of less than 5000-7500 following at least two sequential ABO-compatible fresh platelet transfusions; (3) hepatomegaly is best defined as an absolute increase of at least 1 cm in liver length at the midclavicular line; and if a baseline measurement is not available, hepatomegaly can be defined as greater than 2 SDs above normal for age; and (4) the presence and volume of ascites can be categorised as mild (minimal fluid by liver, spleen, or pelvis), moderate (<1 cm fluid), or severe (fluid in all three regions with >1 cm fluid in at least two regions).

Up-regulation of HDACs, a harbinger of uraemic endothelial dysfunction, is prevented by defibrotide

Endothelial dysfunction is an earlier contributor to the development of atherosclerosis in chronic kidney disease (CKD), in which the role of epigenetic triggers cannot be ruled out. Endothelial protective strategies, such as defibrotide (DF), may be useful in this scenario. We evaluated changes induced by CKD on endothelial cell proteome and explored the effect of DF and the mechanisms involved. Human umbilical cord vein endothelial cells were exposed to sera from healthy donors (n = 20) and patients with end-stage renal disease on haemodialysis (n = 20). Differential protein expression was investigated by using a proteomic approach, Western blot and immunofluorescence. HDAC1 and HDAC2 overexpression was detected. Increased HDAC1 expression occurred at both cytoplasm and nucleus. These effects were dose-dependently inhibited by DF. Both the HDACs inhibitor trichostatin A and DF prevented the up-regulation of the endothelial dysfunction markers induced by the uraemic milieu: intercellular adhesion molecule-1, surface Toll-like receptor-4, von Willebrand Factor and reactive oxygen species. Moreover, DF down-regulated HDACs expression through the PI3/AKT signalling pathway. HDACs appear as key modulators of the CKD-induced endothelial dysfunction as specific blockade by trichostatin A or by DF prevents endothelial dysfunction responses to the CKD insult. Moreover, DF exerts its endothelial protective effect by inhibiting HDAC up-regulation likely through PI3K/AKT.

The Biological and Clinical Relevance of G Protein-Coupled Receptors to the Outcomes of Hematopoietic Stem Cell Transplantation: A Systematized Review

Hematopoietic stem cell transplantation (HSCT) remains the only curative treatment for several malignant and non-malignant diseases at the cost of serious treatment-related toxicities (TRTs). Recent research on extending the benefits of HSCT to more patients and indications has focused on limiting TRTs and improving immunological effects following proper mobilization and engraftment. Increasing numbers of studies report associations between HSCT outcomes and the expression or the manipulation of G protein-coupled receptors (GPCRs). This large family of cell surface receptors is involved in various human diseases. With ever-better knowledge of their crystal structures and signaling dynamics, GPCRs are already the targets for one third of the current therapeutic arsenal. The present paper assesses the current status of animal and human research on GPCRs in the context of selected HSCT outcomes via a systematized survey and analysis of the literature.

Drop of Butyrylcholinesterase Activity after Cyclophosphamide Conditioning as a Predictive Marker of Liver Transplant-Related Complications and Its Correlation with Transplant-Related Mortality in Pediatric Hematopoietic Stem Cell Recipients

Transplant-related liver complications are a potentially fatal condition of hematopoietic stem cell transplantation (HSCT) in pediatric patients, actually representing one of the main factors involved in transplant-related mortality (TRM). The search for a specific marker capable of predicting the development of this condition is a relevant clinical issue. We have observed a variable reduction in serum butyrylcholinesterase (BChE) activity after a cyclophosphamide-containing conditioning regimen. This study aims to determine the cutoff of BChE activity reduction that might be a specific prognostic marker for liver complications after HSCT. Our results show that the reduction of BChE values below 2000 U/L the day before the transplantation is an indicator strongly associated with the transplant-related liver complications (p < 0.0001). The incidence of overall survival at 1 year was significantly higher in the BChE > 2000 U/L group compared to the BChE < 2000 U/L group (84.7% versus 58.5%, p < 0.001), while the TRM rate was significantly lower (8.1% versus 23.1%, p < 0.05). None of the patients undergoing prophylaxis with defibrotide developed severe liver complications. Starting defibrotide treatment at the first signs of hepatic dysfunction in patients with particularly low BChE activity levels reduces severe liver transplant-related complications.