Insights into defibrotide: an updated review

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 impact on the acute GVHD disease incidence in pediatric hematopoietic stem cell transplant recipients

Despite advances in acute graft-versus-host disease (aGVHD) prophylaxis, current pharmacological approaches fail to prevent aGVHD. The protective effect of defibrotide on GVHD incidence and GVHD-free survival has not been sufficiently studied. 91 pediatric patients included in this retrospective study were divided into two groups based on defibrotide use. We compared the incidence of aGVHD and chronic GVHD-free survival between the defibrotide and control groups. The incidence and severity of aGVHD were significantly lower in patients who received defibrotide prophylactic administration than in the control group. This improvement was observed in the liver and intestinal aGVHD. No defibrotide prophylaxis benefit was observed in the prevention of chronic GVHD. The pro-inflammatory cytokine levels were significantly higher in the control group. Our findings suggest that prophylactic administration of defibrotide in pediatric patients significantly reduces the incidence and severity of aGVHD, with a modification of cytokine pattern, both strongly coherent with the protective drug's action. This evidence adds to pediatric retrospective studies and preclinical data suggesting a possible defibrotide role in this setting.

Hepatic sinusoidal obstruction syndrome caused by the ingestion of Gynura segetum in a patient with alcoholic cirrhosis: a case report

Hepatic sinusoidal obstruction syndrome (HSOS) is a rare hepatic vascular disorder characterized by intrahepatic congestion, liver injury, and post-sinusoidal portal hypertension, and it is frequently associated with hematopoietic stem cell transplantation. In this study, we observed a case of HSOS associated with the ingestion of Gynura segetum, a pyrrolizidine alkaloid (PA)-containing Chinese herb, in a patient with alcoholic cirrhosis. The patient was a 43-year-old man with chief complaints of physical asthenia and a loss of appetite for more than a month. The diagnosis of HSOS combined with alcoholic cirrhosis was confirmed via the histopathological examination of liver tissues. With proper supportive and symptomatic care and anticoagulation therapy using low-molecular-weight heparin, the patient’s condition was stabilized. Because of its nonspecific symptoms in the early stage and a lack of information about PA consumption, PA-induced HSOS (PA-HSOS) has been long neglected, especially in patients with underlying liver diseases. Early identification and intervention are critical for optimizing outcomes. Further efforts are needed to supervise the use of PA-containing herbal medicines and identify accurate biomarkers for PA-HSOS.

Defibrotide inhibits donor leucocyte-endothelial interactions and protects against acute graft-versus-host disease

Allogeneic hematopoietic stem cell transplantation (allo‐HCT) is an effective therapy for the treatment of high‐risk haematological malignant disorders and other life‐threatening haematological and genetic diseases. Acute graft‐versus‐host disease (aGvHD) remains the most frequent cause of non‐relapse mortality following allo‐HCT and limits its extensive clinical application. Current pharmacologic agents used for prophylaxis and treatment of aGvHD are not uniformly successful and have serious secondary side effects. Therefore, more effective and safe prophylaxis and therapy for aGvHD are an unmet clinical need. Defibrotide is a multi‐target drug successfully employed for prophylaxis and treatment of veno‐occlusive disease/sinusoidal obstruction syndrome. Recent preliminary clinical data have suggested some efficacy of defibrotide in the prevention of aGvHD after allo‐HCT. Using a fully MHC‐mismatched murine model of allo‐HCT, we report here that defibrotide, either in prophylaxis or treatment, is effective in preventing T cell and neutrophil infiltration and aGvHD‐associated tissue injury, thus reducing aGvHD incidence and severity, with significantly improved survival after allo‐HCT. Moreover, we performed in vitro mechanistic studies using human cells revealing that defibrotide inhibits leucocyte‐endothelial interactions by down‐regulating expression of key endothelial adhesion molecules involved in leucocyte trafficking. Together, these findings provide evidence that defibrotide may represent an effective and safe clinical alternative for both prophylaxis and treatment of aGvHD after allo‐HCT, paving the way for new therapeutic approaches.

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.

Treatment of Thrombotic Antiphospholipid Syndrome: The Rationale of Current Management-An Insight into Future Approaches

Vascular thrombosis and pregnancy morbidity represent the clinical manifestations of antiphospholipid syndrome (APS), which is serologically characterized by the persistent positivity of antiphospholipid antibodies (aPL). Antiplatelet and anticoagulant agents currently provide the mainstay of APS treatment. However, the debate is still open: controversies involve the intensity and the duration of anticoagulation and the treatment of stroke and refractory cases. Unfortunately, the literature cannot provide definite answers to these controversial issues as it is flawed by many limitations, mainly due to the recruitment of patients not fulfilling laboratory and clinical criteria for APS. The recommended therapeutic management of different aPL-related clinical manifestations is hereby presented, with a critical appraisal of the evidence supporting such approaches. Cutting edge therapeutic strategies are also discussed, presenting the pioneer reports about the efficacy of novel pharmacological agents in APS. Thanks to a better understanding of aPL pathogenic mechanisms, new therapeutic targets will soon be explored. Much work is still to be done to unravel the most controversial issues about APS management: future studies are warranted to define the optimal management according to aPL risk profile and to assess the impact of a strict control of cardiovascular risk factors on disease control.

Heparanase polymorphisms: influence on incidence of hepatic sinusoidal obstruction syndrome in children undergoing allogeneic hematopoietic stem cell transplantation

PURPOSE

Sinusoidal obstruction syndrome (SOS) is a life-threatening early complication after hematopoietic stem cell transplantation (HSCT), and until now, examinations about the influence of genetic risk factors are extremely rare. The purpose of this study was to identify an association between heparanase (HPSE) single nucleotide polymorphisms (SNPs) and SOS in children undergoing allogeneic HSCT.

METHODS

We retrospectively analyzed the distribution of the both HPSE SNPs rs4693608 and rs4364254 and the occurrence of SOS after allogeneic HSCT in 160 children with malignant and non-malignant diseases.

RESULTS

Patients with HPSE genotypes GG or AG of rs4693608 (G>A) had a significantly reduced incidence of SOS on day 100 after HSCT compared to patients with genotype AA (4.7 vs. 14.3 %, P = 0.038). In addition, incidence of SOS in patients with genotype CC or CT of rs4364254 (C>T) was significantly decreased in comparison with patients with genotype TT (2.3 vs. 14.7 %, P = 0.004). Interestingly, no patient with genotype CC developed SOS. Because both SNPs co-occur in vivo, we generated subsets: AA-TT, GG-CC, and a group with remaining SNP combinations. We found significant differences between all three patient groups (P = 0.035). Patients with AA-TT showed the highest incidence of SOS (16.7 %), while SOS did not appear in patients with GG-CC (0 %) and residual combinations were numerically in-between (4.9 %). An impact caused by main patient and donor characteristics, established risk factors for SOS, and conditioning regimen could be excluded in multivariate analyses.

CONCLUSIONS

HPSE polymorphisms turned out to be significant independent risk factors (P = 0.030) for development of SOS and should be evaluated in further trials.

Oligodeoxyribonucleotides derived from salmon sperm DNA: an alternative to defibrotide

Defibrotide is a single-stranded nucleic acid polymer originally derived from porcine mucosa. Cheap salmon sperm DNA is commercially available and widely used in drug production. In this study, oligodeoxyribonucleotides were successfully obtained from the controlled depolymerization of salmon sperm DNA. The obtained product shared similar chemical and biological properties with defibrotide produced by Gentium SpA, Italy. It was also found that oligodeoxyribonucleotides derived from non-mammalian origins could also directly stimulate tissue plasminogen activator (t-PA) release from cultured human endothelial cells, and enhance fibrinolytic activity in the rabbit.

Drug safety evaluation of defibrotide

INTRODUCTION

Hepatic veno-occlusive disease (VOD), also known as sinusoidal obstruction syndrome (SOS), is a potentially life-threatening complication of chemotherapeutic conditioning used in preparation for hematopoietic stem-cell transplantation (SCT). Defibrotide (DF) has been shown in Phase II and III trials to improve complete response in patients with severe VOD (sVOD). None of the articles, to date, provide a comprehensive review of the safety of DF in VOD and/or a range of other conditions.

AREAS COVERED

This article reviews current clinical findings on DF, primarily in terms of safety for use in treatment and prophylaxis of VOD, and relevant safety data for its use in other diseases. The literature review was conducted using a PubMed search with the fixed term 'defibrotide' in combination with ≥ 1 of 'safety', 'veno-occlusive disease' (with and without 'treatment', 'prevention'), 'oncology', 'myeloma', 'microangiopathy', 'anti-thrombotic' and 'peripheral vascular disorder'. Related articles from the EBMT and ASH conference websites were also included.

EXPERT OPINION

DF was well tolerated in majority of the studies. The safety profile of DF is largely favourable with toxicities comparable to control populations in the setting of SCT complicated by sVOD.

Defibrotide for the prevention of hepatic veno-occlusive disease after hematopoietic stem cell transplantation: a systematic review

Prophylactic use of defibrotide (DF) to prevent veno-occlusive disease (VOD), a relatively common and high-risk complication of hematopoietic stem cell transplantation (HSCT), may be an encouraging modality to reduce morbidity and mortality from VOD. However, conclusions remain unclear. We carried out a systematic review to summarize the state of knowledge. One randomized controlled trial (RCT), four cohort studies and eight case series studies were found, including a total of 1230 patients. The overall mean incidence of VOD in patients using DF was 4.7% (95% CI, 3.3-6.1) which was significantly lower than the data 13.7% (95% CI, 13.3-14.1) across 135 studies using no VOD prophylaxis (p < 0.005). The meta-analysis of the incidence of VOD in controlled trials revealed a statistical reduction in VOD incidence in the DF group (RR = 0.47, 95% CI, 0.31-0.73). The overall mean incidence of severe VOD was 0.8% (95% CI, 0.2-1.4). The RR was 0.31 (95% CI, 0.09-1.06). However, the lack of RCTs and the methodological weaknesses of the studies may preclude making generalizable conclusions. Our review described that DF appears promising for VOD prevention and large RCT is needed for further confirmation.

Effect of prednisone on transforming growth factor-β1, connective tissue growth factor, nuclear factor-κBp65 and tumor necrosis factor-α expression in a murine model of hepatic sinusoidal obstruction syndrome induced by Gynura segetum

AIM

  One major cause of hepatic sinusoidal obstruction syndrome (HSOS) is the consumption of products containing pyrrolizidine alkaloids (PA). As the use of herbal preparations has increased in China, so has the number of reports of HSOS induced by ingesting PA-containing herbs. The aim of the present study was to investigate the mechanisms by which prednisone and the related factors, transforming growth factor (TGF)-β1 and connective tissue growth factor (CTGF), prevent liver fibrosis and the pathogenesis of HSOS.

METHODS

  A murine model of HSOS was created by oral gavage with Gynura segetum with or without prednisone for 30 days. Histological changes in liver tissue were evaluated by a scoring system in tissue slices subjected to hematoxylin-eosin and Masson trichrome staining. Hepatic expression of TGF-β1 and CTGF mRNA and protein was detected by immunohistochemistry, reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. RT-PCR was also used to detect tumor necrosis factor (TNF)-α and nuclear factor (NF)-κBp65 mRNA expression. Activation of NF-κBp65 was detected by immunohistochemistry.

RESULTS

  Intervention with prednisone diminished the symptoms of HSOS in mice treated with G. segetum. Prednisone treatment significantly inhibited expression of TGF-β1 and CTGF mRNA and protein (P < 0.05), and inhibited expression of TNF-α and NF-κBp65 mRNA (P < 0.05) in the liver tissue of HSOS mice.

CONCLUSION

  Prednisone suppresses the development of liver fibrosis in HSOS mice by inhibiting TGF-β1, CTGF, TNF-α and NF-κBp65 expression.

Effect of ligustrazine on mice model of hepatic veno-occlusive disease induced by Gynura segetum

BACKGROUND AND AIM

To investigate the therapeutic effect of ligustrazine on hepatic veno-occlusive disease (HVOD) induced by Gynura segetum and the possible mechanism of it.

METHODS

Female Kunming mice (115) were randomly divided into four groups, gavaged with 30 g/kg per day Gynura segetum (group A), 30 g/kg per day Gynura segetum + 100 mg/kg per day ligustrazine (group B), 30 g/kg per day Gynura segetum + 200 mg/kg per day ligustrazine (group C) or 30 mL/kg per day phosphate-buffered saline (PBS) (group D). Thirty days later, all of the mice were killed. Blood samples and livers were harvested. Histological changes were evaluated by light microscopy. Liver function was measured, and the expression of tissue factor (TF), early growth response factor-1 (Egr-1) and nuclear factor-KBp65 (NF-KBp65) were determined by reverse transcription-polymerase chain reaction and Western blot.

RESULTS

A total of 24 mice in group A developed HVOD. Compared with the controls, they had increased liver ratio, serum total bilirubin (TBIL), direct bilirubin (DBIL), transaminase and decreased albumin (ALB) (P < 0.05). Administration of ligustrazine improved the clinical signs and biochemistry parameters in a dose-dependent manner. Compared with group A, the expression of TF, Egr-1 and NF-KB p65 decreased in groups B and C (P < 0.05).

CONCLUSION

Ligustrazine has a therapeutic effect on HVOD, improving clinical manifestations and liver function. The possible mechanism may be that ligustrazine could reduce the expression of TF by downregulating the expression of transcription factors: Egr-1 and NF-KB p65.

Management of refractory cases of catastrophic antiphospholipid syndrome

The catastrophic variant of the antiphospholipid syndrome (APS) is the most severe form of APS with acute multiple organ involvement and small vessel thrombosis. Refractory catastrophic APS may be defined as patients who did not respond to first-line therapies (anticoagulation, glucocorticoids and plasma exchange and/or intravenous immunoglobulins) and died in the acute phase of the episode or patients with recurrent episodes of catastrophic APS. The purpose of this review is to focus on the current management of these refractory patients and some of the potential new therapeutic approaches.