defibrotide and Thrombotic-Microangiopathies

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.

Topics: Adult; Capillary Permeability; Child; Endothelial Cells; Endothelium, Vascular; Forecasting; Graft vs Host Disease; Hematopoietic Stem Cell Transplantation; Hepatic Veno-Occlusive Disease; Humans; Idiopathic Interstitial Pneumonias; Immunotherapy, Adoptive; Inflammation; Multiple Organ Failure; Polydeoxyribonucleotides; Thrombophilia; Thrombotic Microangiopathies; Transplantation Conditioning

Endothelial cells are unique multifunctional cells with basal and inducible metabolic and synthetic functions. Various stimuli can induce physiological or pathological changes in endothelial cell biology. Hematopoietic stem cell transplantation (HSCT) requires high-dose irradiation and/or chemotherapy and is associated with increased risk of bacterial infections and immune reactions. These factors can affect endothelial cells. This review provides an overview of the effects of HSCT on endothelial cells, based on findings observed in cultured cells as well as in patients. We first describe to what extent irradiation and chemotherapy constitute direct and indirect triggers for endothelial cell activation and injury. Then, we highlight the role of the endothelium in several complications of HSCT, including capillary leak syndrome, engraftment syndrome, transplant-associated microangiopathy, graft-versus-host disease, and diffuse alveolar hemorrhages. We also analyze in detail available data on sinusoidal obstruction syndrome, previously known as veno-occlusive disease of the liver, where liver sinusoidal endothelial cells are first injured and eventually lead to sinusoid occlusion and liver cell damage. Finally, we open the question of the possible contribution of endothelial damage to cardiovascular events occurring long after HSCT.

Topics: Angiogenic Proteins; Animals; Anticoagulants; Bone Marrow Transplantation; Capillary Leak Syndrome; Cardiovascular Diseases; Cell Adhesion Molecules; Cell-Derived Microparticles; Endothelium, Vascular; Fever; Graft vs Host Disease; Hematologic Diseases; Hematopoietic Stem Cell Transplantation; Hepatic Veno-Occlusive Disease; Humans; Immunosuppressive Agents; Inflammation; Nitric Oxide; Polydeoxyribonucleotides; Pulmonary Veno-Occlusive Disease; Radiation Injuries; Syndrome; Thrombotic Microangiopathies; Transplantation Conditioning

Transplant-associated thrombotic microangiopathy (TA-TMA) is an endothelial injury complication of hematopoietic stem cell transplant (HSCT) leading to end-organ damage and high morbidity and mortality. Defibrotide is an anti-inflammatory and antithrombotic agent that may protect the endothelium during conditioning.. We hypothesized that prophylactic use of defibrotide during HSCT conditioning and acute recovery could prevent TA-TMA. A pilot single-arm phase II trial (NCT#03384693) evaluated the safety and feasibility of administering prophylactic defibrotide to high-risk pediatric patients during HSCT and assessed if prophylactic defibrotide prevented TA-TMA compared to historic controls. Patients received defibrotide 6.25 mg/kg IV q6h the day prior to the start of conditioning through day +21. Patients were prospectively monitored for TA-TMA from admission through week 24 post transplant. Potential biomarkers of endothelial injury (suppression of tumorigenicity 2 [ST2], angiopoietin-2 [ANG-2], plasminogen activator inhibitor-1 [PAI-1], and free hemoglobin) were analyzed.. Twenty-five patients were enrolled, 14 undergoing tandem autologous HSCT for neuroblastoma and 11 undergoing allogeneic HSCT. Defibrotide was discontinued early due to possibly related clinically significant bleeding in 12% (3/25) of patients; no other severe adverse events occurred due to the study intervention. The other 22 patients missed a median of 0.7% of doses (0%-5.2%). One patient developed nonsevere TA-TMA 12 days post HSCT. This observed TA-TMA incidence of 4% was below the historic rate of 18%-40% in a similar population of allogeneic and autologous patients.. Our study provides evidence that defibrotide prophylaxis is feasible in pediatric patients undergoing HSCT at high risk for TA-TMA and preliminary data indicating that defibrotide may reduce the risk of TA-TMA.

Topics: Child; Hematopoietic Stem Cell Transplantation; Humans; Pilot Projects; Polydeoxyribonucleotides; Risk Assessment; Thrombotic Microangiopathies

Defibrotide is approved in European Union for the treatment of severe sinusoidal obstruction syndrome (SOS) after HSCT. However, it has also been used for SOS prophylaxis, moderate SOS and in other complications such as transplant-associated thrombotic microangiopathy (TAM). The objective of this study was to evaluate current uses, effectiveness and safety of defibrotide in patients with HSCT.. This multicenter, retrospective study included patients treated with defibrotide for any indication at 28 HSCT centers of the Grupo Español de Trasplante Hematopoyetico (GETH) including the pediatric subgroup Grupo Español de Trasplante de Medula en Niños (GETMON).. Three hundred and eighty eight patients treated with defibrotide between January 2011 and December 2018 were included. 253 patients were children, and 135 patients were adults. In total, 332 transplants were allogeneic, and the remainder were autologous. Main indications for defibrotide use were severe/very severe SOS in 173 patients, SOS prophylaxis in 135 patients, moderate SOS in 41 patients, TAM in six patients and suspected SOS in 33 patients. Overall survival (OS) at day +100 in the SOS prophylaxis group was 89% (95% CI, 87%-91%). In the group of patients with moderate and severe/very severe SOS, the OS at day +100 was 80% (95% CI, 74%-86%) and 62% (95% CI, 59%-65%), respectively (P = .0015). With a longer follow-up, median of 2 years (4 months-7 years), OS was 63% (95% CI, 59%-67%) in the SOS prophylaxis patients. OS for patients with moderate and severe/very severe SOS groups was 53% (95% CI, 47%-61%) and 26% (95% CI, 22%-30%), respectively (P = .006). 191 patients died, and SOS was the main cause of death in 23 patients (12%).. Defibrotide has an acceptable safety profile with an improved response in severe/very severe SOS compared with historical controls, mainly in pediatric patients. Use of defibrotide for prophylaxis may improve prognosis of patients at high risk of complications due to endothelial damage such as those who receive a second transplant. SOS has an important impact on the HSCT long-term survival, as can be concluded from our study.

Topics: Adolescent; Adult; Aged; Allografts; Child; Child, Preschool; Disease-Free Survival; Female; Hematopoietic Stem Cell Transplantation; Humans; Infant; Male; Middle Aged; Polydeoxyribonucleotides; Retrospective Studies; Spain; Survival Rate; Thrombotic Microangiopathies

Topics: Anemia, Sickle Cell; Anticoagulants; Apoptosis; Bone Marrow Transplantation; COVID-19; Endothelial Cells; Endothelium, Vascular; Glucuronidase; Graft vs Host Disease; Heparin; Hepatic Veno-Occlusive Disease; Humans; Idiopathic Interstitial Pneumonias; Interleukin-6; Multiple Organ Failure; Organ Specificity; Pandemics; Polydeoxyribonucleotides; SARS-CoV-2; Stem Cell Transplantation; Thrombophilia; Thrombotic Microangiopathies; Vasculitis; Viral Tropism

We report the results of a single-center analysis of a cohort of 39 patients treated between 1997 and 2016 for transplantion-associated thrombotic microangiopathy. We evaluated 2 subgroups of patients: 24 patients treated between 1997 and 2014 who received conventional therapy and 15 patients treated with the complement-inhibiting monoclonal antibody eculizumab between 2014 and 2016. The conventional therapy group was treated predominantly with defibrotide alone or in combination with plasmapheresis or rituximab. Despite an initial response rate of 61%, only 4 patients (16%) were long-term survivors, 2 of whom had a low-risk thrombotic microangiopathy without multiorgan damage. Progression of thrombotic micorangiopathy and bacterial/fungal infections contributed equally to treatment failure. The overall response rate in the eculizumab group was significantly higher, at 93%. In addition, we were able to stop eculizumab treatment in 5 patients (33%), all of whom had high-risk thrombotic microangiopathy, due to sustained recovery. Despite the very good response in the eculizumab-treated group, we did not observe a significant improved overall survival, due primarily to a high rate of infection-related mortality (70%). Therefore, further studies are needed to identify the optimal therapeutic management approach for transplantation-associated thrombotic microangiopathy to improve its dismal outcome.

Topics: Adult; Aged; Antibodies, Monoclonal, Humanized; Humans; Infections; Middle Aged; Polydeoxyribonucleotides; Stem Cell Transplantation; Survival Analysis; Thrombotic Microangiopathies; Transplantation, Homologous; Treatment Outcome; Young Adult

Topics: Adult; Allografts; Bone Marrow Transplantation; Child; Child, Preschool; Europe; Female; Genetic Diseases, Inborn; Hematopoietic Stem Cell Transplantation; Humans; Infant; Infant, Newborn; Male; Middle Aged; Polydeoxyribonucleotides; Retrospective Studies; Societies, Medical; Thrombotic Microangiopathies