Hepatic veno-occlusive disease after hematopoietic stem cell transplantation: update on defibrotide and other current investigational therapies

Incidence of sinusoidal obstruction syndrome/veno-occlusive disease and treatment with defibrotide in allogeneic transplant: A multicentre Australasian registry study

BACKGROUND

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) is an established complication in patients undergoing allogeneic haemopoietic stem cell transplantation. Defibrotide is an effective and safe pharmacological option for treating diagnosed SOS/VOD.

OBJECTIVE

By exploring data provided to the Australasian Bone Marrow Transplant Recipient Registry (ABMTRR) by centres from Australia and New Zealand, this study aimed to describe the incidence of SOS/VOD and patterns of defibrotide use from 2016 to 2020.

STUDY DESIGN

Patients who underwent allogeneic HSCT between 2016 and 2020 were identified from the ABMTRR. Data was extracted for a total of 3346 patients, 2692 from adult centres and 654 from paediatric centres, with a median follow up of 21.5 months and 33.3 months respectively. Descriptive statistics were used to describe the patient population, including the incidence of SOS/VOD and defibrotide use. Comparisons were made between patients not experiencing SOS/VOD, and those with the diagnosis, divided into defibrotide and no-defibrotide cohorts. Associations with overall survival and day 100 survival with variables such as gender, age, disease at transplant, source of stem cells, conditioning agents, SOS/VOD diagnosis and use of defibrotide were determined.

RESULTS

The reported incidence of SOS/VOD was 4.1% in adult centres and 11.5% in paediatric centres. Defibrotide was administered to 74.8% of adult patients with SOS/VOD and 97.3% of paediatric patients. Significant variability of use, dose and duration of defibrotide was seen across the adult centres. Day 100 survival rate and median overall survival (OS) for patients managed with defibrotide was 51.8% and 103 days respectively for adult patients, and 90.4% and not reached for paediatric patients. In adults, older age at transplant, an HLA matched donor who was a non-sibling relative, and a diagnosis of SOS/VOD treated with defibrotide, were all associated with reduced OS. In paediatrics, the patient and transplant characteristics that were associated with a reduced OS were a diagnosis of SOS/VOD and donor relation as 2 or more HLA mismatched relative.

CONCLUSION

A collaborative approach across Australasia to diagnose and manage SOS/VOD, in particular with respect to consistent defibrotide use, is recommended.

Molecular Advances in Sinusoidal Obstruction Syndrome/Veno-Occlusive Disease

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

Oncologic emergencies and urgencies: A comprehensive review

Patients with advanced cancer generate 4 million visits annually to emergency departments (EDs) and other dedicated, high-acuity oncology urgent care centers. Because of both the increasing complexity of systemic treatments overall and the higher rates of active therapy in the geriatric population, many patients experiencing acute decompensations are frail and acutely ill. This article comprehensively reviews the spectrum of oncologic emergencies and urgencies typically encountered in acute care settings. Presentation, underlying etiology, and up-to-date clinical pathways are discussed. Criteria for either a safe discharge to home or a transition of care to the inpatient oncology hospitalist team are emphasized. This review extends beyond familiar conditions such as febrile neutropenia, hypercalcemia, tumor lysis syndrome, malignant spinal cord compression, mechanical bowel obstruction, and breakthrough pain crises to include a broader spectrum of topics encompassing the syndrome of inappropriate antidiuretic hormone secretion, venous thromboembolism and malignant effusions, as well as chemotherapy-induced mucositis, cardiomyopathy, nausea, vomiting, and diarrhea. Emergent and urgent complications associated with targeted therapeutics, including small molecules, naked and drug-conjugated monoclonal antibodies, as well as immune checkpoint inhibitors and chimeric antigen receptor T-cells, are summarized. Finally, strategies for facilitating same-day direct admission to hospice from the ED are discussed. This article not only can serve as a point-of-care reference for the ED physician but also can assist outpatient oncologists as well as inpatient hospitalists in coordinating care around the ED visit.

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

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

Low-dose unfractionated heparin prophylaxis is a safe strategy for the prevention of hepatic sinusoidal obstruction syndrome after myeloablative adult allogenic stem cell transplant

Hepatic sinusoidal obstruction syndrome (SOS) is a serious complication after allogeneic stem cell transplantation (allo-HCT). However, there is no uniform consensus on the optimal strategy for SOS prevention. Ursodeoxycholic acid is the most used regimen, even though its administration is challenging in recipients unable to tolerate oral medication. Defibrotide was recently studied in a phase 3 trial, but enrollment was stopped early due to futility. Low dose unfractionated heparin (UFH) is an alternative strategy. However, its efficacy is reputed but unproven increased risk of bleeding has not been fully established. We evaluated 514 adult allo-HCT recipients who received SOS prophylaxis with low dose UFH. Bleeding complications occurred in 12 patients 2.3% of patients of which only 2 (0.4%) had significant grade 3 bleeding. Only 14 patients were diagnosed with hepatic SOS. Univariate analysis showed that day 100 SOS was higher in recipients of unmodified grafts when compared to CD34+ selected ex vivo T-cell depleted grafts (p ≤ 0.001), and patients with hepatitis B and/or C exposure pre-HCT (p = 0.028). Overall, UFH was well tolerated and associated with a low incidence of subsequent hepatic SOS. Low dose UFH prophylaxis can be considered in select patients who cannot tolerate oral ursodiol.

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.

Defibrotide inhibits antiphospholipid antibody-mediated NET formation and venous thrombosis

OBJECTIVES

Defibrotide is a heterogenous mixture of polyanionic oligonucleotides currently approved for treatment of transplant-associated veno-occlusive disease. While defibrotide has a known role in limiting endothelial cell activation, some studies have also demonstrated anti-leukocyte properties. We recently revealed a role for neutrophil extracellular traps (NETs) in the thrombotic complications of antiphospholipid syndrome (APS). Here, we hypothesized that defibrotide might act to mitigate APS-relevant NET formation in vitro and in mouse models.

METHODS

We used in vitro assays and a mouse model to determine mechanisms by which defibrotide inhibits NET formation and venous thrombosis in APS.

RESULTS

At doses ranging from 1 to 10 μg ml^-1 , defibrotide significantly suppressed NET formation from control neutrophils stimulated with IgG isolated from APS patients. Defibrotide increased levels of intracellular cyclic AMP in neutrophils, and its suppressive effects on NET formation were mitigated by blocking adenosine A_2A receptor or by inhibiting the cyclic AMP-dependent kinase, protein kinase A. Defibrotide at doses ranging from 15 to 150 mg/kg/day inhibited NET formation and venous thrombosis in a model of antiphospholipid antibody-accelerated thrombosis-an effect that was reduced in adenosine A_2A receptor knockout mice.

CONCLUSION

This study is the first to demonstrate mechanisms by which defibrotide counteracts neutrophil-mediated thrombo-inflammation inherent to APS.

Pyrrolizidine Alkaloid-Induced Hepatotoxicity Associated with the Formation of Reactive Metabolite-Derived Pyrrole-Protein Adducts

Pyrrolizidine alkaloids (PAs) with 1,2-unsaturated necine base are hepatotoxic phytotoxins. Acute PA intoxication is initiated by the formation of adducts between PA-derived reactive pyrrolic metabolites with cellular proteins. The present study aimed to investigate the correlation between the formation of hepatic pyrrole-protein adducts and occurrence of PA-induced liver injury (PA-ILI), and to further explore the use of such adducts for rapidly screening the hepatotoxic potency of natural products which contain PAs. Aqueous extracts of Crotalaria sessiliflora (containing one PA: monocrotaline) and Gynura japonica (containing two PAs: senecionine and seneciphylline) were orally administered to rats at different doses for 24 h to investigate PA-ILI. Serum alanine aminotransferase (ALT) activity, hepatic glutathione (GSH) level, and liver histological changes of the treated rats were evaluated to assess the severity of PA-ILI. The levels of pyrrole-protein adducts formed in the rats' livers were determined by a well-established spectrophotometric method. The biological and histological results showed a dose-dependent hepatotoxicity with significantly different toxic severity among groups of rats treated with herbal extracts containing different PAs. Both serum ALT activity and the amount of hepatic pyrrole-protein adducts increased in a dose-dependent manner. Moreover, the elevation of ALT activity correlated well with the formation of hepatic pyrrole-protein adducts, regardless of the structures of different PAs. The findings revealed that the formation of hepatic pyrrole-protein adducts-which directly correlated with the elevation of serum ALT activity-was a common insult leading to PA-ILI, suggesting a potential for using pyrrole-protein adducts to screen hepatotoxicity and rank PA-containing natural products, which generally contain multiple PAs with different structures.

Tu-San-Qi (Gynura japonica): the culprit behind pyrrolizidine alkaloid-induced liver injury in China

Herbs and dietary supplement-induced liver injury (HILI) is the leading cause of drug-induced liver injury in China. Among different hepatotoxic herbs, the pyrrolizidine alkaloid (PA)-producing herb Gynura japonica contributes significantly to HILI by inducing hepatic sinusoidal obstruction syndrome (HSOS), a liver disorder characterized by hepatomegaly, hyperbilirubinemia, and ascites. In China, G. japonica has been used as one of the plant species for Tu-San-Qi and is often misused with non-PA-producing Tu-San-Qi (Sedum aizoon) or even San-Qi (Panax notoginseng) for self-medication. It has been reported that over 50% of HSOS cases are caused by the intake of PA-producing G. japonica. In this review, we provide comprehensive information to distinguish these Tu-San-Qi-related herbal plant species in terms of plant/medicinal part morphologies, medicinal indications, and chemical profiles. Approximately 2156 Tu-San-Qi-associated HSOS cases reported in China from 1980 to 2019 are systematically reviewed in terms of their clinical manifestation, diagnostic workups, therapeutic interventions, and outcomes. In addition, based on the application of our developed mechanism-based biomarker of PA exposure, our clinical findings on the definitive diagnosis of 58 PA-producing Tu-San-Qi-induced HSOS patients are also elaborated. Therefore, this review article provides the first comprehensive report on 2214 PA-producing Tu-San-Qi (G. japonica)-induced HSOS cases in China, and the information presented will improve public awareness of the significant incidence of PA-producing Tu-San-Qi (G. japonica)-induced HSOS and facilitate future prevention and better clinical management of this severe HILI.

Busulfan-containing conditioning regimens in allogeneic hematopoietic stem cell transplantation for acute lymphoblastic leukemia: A Taiwan observational study

Background

Allogeneic stem cell transplantation (allo‐HSCT) is the ultimate cure for acute lymphoblastic leukemia (ALL).

Aim

This study was performed to compare the outcomes of ALL patients receiving busulfan (Bu) with cyclophosphamide (Cy)‐based or total body irradiation (TBI)‐based regimen in a Chinese population.

Methods

We enrolled 224 adult patients with ALL who received allo‐HSCT at National Taiwan University Hospital between 1997 and 2016.

Results

The median age at transplantation was 33 years. Before allo‐HSCT, 75.9% of patients attained first or late complete remission. A total of 141 patients (62.9%) received Bu/Cy‐based conditioning, either myeloablative (MA) or reduced‐intensity stem cell transplantation (RIST), and 83 patients received a TBI‐based regimen (MA‐TBI). Patients receiving the MA‐Bu regimen had longer relapse‐free survival (RFS) than those receiving the MA‐TBI regimen (median, 24.1 vs. 6.7 months, p = .044). There was no difference in overall survival (OS, MA‐Bu vs. MA‐TBI vs. RIST‐Bu: 39.4 vs. 28.2 vs. 13.1 months, p = .276), treatment‐related mortality (TRM), or incidences of grade 3–4 acute graft‐versus‐host disease (GvHD). Among patients receiving identical GvHD prophylactic regimens, there was no difference between MA‐Bu and MA‐TBI groups regarding the incidence of grade 3–4 acute GvHD, grade 2–4, and all‐grade chronic GvHD. In subgroup analysis, patients receiving oral busulfan had comparable RFS and OS to the intravenous busulfan group (p = .436 and p = .236, respectively), but a higher TRM (25% vs. 9.8%, p = .016). In the multivariable analysis, disease status before allo‐HSCT was the only risk factor impacting RFS and OS.

Conclusion

In summary, patients receiving Bu/Cy‐based or TBI‐based regimens as conditioning had similar results in terms of OS, TRM, and acute GvHD, whereas the use of myeloablative Bu/Cy resulted in a better RFS. A Bu‐based regimen could be an alternative conditioning choice for patients who are ineligible to receive TBI. Prospective and randomized controlled trials are warranted to validate the long‐term outcomes.

Defibrotide in hematopoietic stem cell transplantation: A multicenter survey study of the Spanish Hematopoietic Stem Cell Transplantation Group (GETH)

BACKGROUND

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.

METHODS

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).

RESULTS

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%).

CONCLUSIONS

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.

Evaluation of Reversed Administration Order of Busulfan (BU) and Cyclophosphamide (CY) as Conditioning on Liver Toxicity in Allogenic Hematopoietic Stem Cell Transplantation (ALL-HSCT)

Background: Busulfan (BU) in combination with cyclophosphamide (CY) is used as an effective conditioning regimen in hematopoietic SCT. Busulfan, depletes glutathione level in liver and causes elevated levels of CY metabolites. Cyclophosphamide metabolites are highly toxic for sinusoidal endothelial cells and cause VOD/ SOS with high mortality rate.

Materials and Methods: Between September 2013 and September 2015, all adult patients with acute leukemia who were candidates for myeloablative allogenic SCT and were admitted to Stem Cell Transplantation center were enrolled in this prospective randomized clinical trial. We tested the hypothesis that reverse administration from BU-CY (n=28) to CY-BU group (n=27) would reduce liver toxicity.

Results: Liver function tests were significantly higher in the BU-CY group between day -1 and +4 (p<0.05), but VOD/SOS was not diagnosed in both groups. The incidence and severity of acute GVHD was higher in the BU-CY group, but not statistically significant. Engraftment and mortality rate were not different.

Conclusion: These data support the concept that CY-BU is associated with less liver toxicity, suggesting CY-BU is superior to BU-CY as conditioning.

An update on the management of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by recurrent venous or arterial thrombosis with or without pregnancy morbidity in the presence of persistent antiphospholipid (aPL) autoantibodies. Anticoagulation has, until now, formed the cornerstone of treatment but a significant proportion of patients continue to experience thrombosis and pregnancy morbidity despite this treatment. Thrombosis is the most common cause of mortality and accounts for two fifths of deaths. Direct oral anticoagulant drugs represent an attractive alternative to conventional vitamin K antagonist drugs but emerging evidence suggests these may not be suitable for high-risk patients with thrombotic APS. Laboratory studies and case reports of the successful use of different classes of drugs in APS is increasing our understanding of the other pathophysiological mechanisms which may contribute to the high morbidity of APS. This review summarizes current accepted anticoagulant treatment for APS and examines other potential drugs such as immunomodulating agents, statins and novel agents such as sirolimus and defibrotide.

What the Intensivist Needs to Know About Hematopoietic Stem Cell Transplantation?

Hematopoietic stem cell transplantation (HSCT) is a potential curative therapy for some patients with hematologic conditions. There are two main types of HSCT. This includes autologous HSCT, for which the stem cells are obtained from the patient, and allogeneic HSCT, for which the stem cells are obtained from a related or unrelated donor. The most common indications for autologous stem cell transplant are multiple myeloma and relapsed/refractory lymphoma, whereas leukemia and bone marrow failure syndromes remain the most common indications for allogeneic stem cell transplant. This chapter will review the different types, indications, processes, and main complications of HSCT. This chapter will also discuss end-of-life issues that patients and providers face when transplant patients are admitted for the intensive care unit.

Incidence, Predictors, and Outcomes of Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome after Reduced-Intensity Allogeneic Hematopoietic Cell Transplantation

fludarabine with intravenous busulfan at doses of 3.2 mg/kg (Flu/Bu1) or 6.4 mg/kg (Flu/Bu2). Hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a serious complication of hematopoietic stem cell transplantation (HCT) that is felt to be triggered, at least in part, by damage to the liver sinusoidal endothelium from cytotoxic conditioning regimens. Accordingly, the incidence of VOD/SOS after reduced-intensity conditioning (RIC) HCT is low compared with myeloablative transplantation, and the natural history, risk factors, and outcomes of VOD/SOS after RIC have not been well characterized. We retrospectively reviewed 1583 consecutive patients receiving RIC HCT at the Dana-Farber Cancer Institute between 2007 and 2017 and ascertained 26 cases of VOD/SOS. The median day of VOD/SOS onset was 26 days (range, 5 to 48) and the cumulative incidence at day 50 was 1.6% (95% confidence interval [CI], 1.1% to 2.4%). Day 100 nonrelapse mortality rate was 23% in the VOD/SOS cohort compared with 6.4% in patients without VOD/SOS (P = .006). Cumulative incidence of VOD/SOS at day 50 was 3.1% after RIC regimen with Flu/Bu2 ± ATG (fludarabine with two doses of busulfan, total dose 6.4 mg/kg, with or without anti-thymocyte globulin), compared with 0.15% after Flu/Bu1 ± ATG (fludarabine with single busulfan dose 3.2 mg/kg, with or without anti-thymocyte globulin) (P = .0002); the incidence rate was 2.1% after RIC HCT with sirolimus-containing graft-versus-host disease prophylaxis, compared with 0.8% for RIC without sirolimus (P = .06). Significant risk factors identified in multivariable analysis for the development of VOD/SOS were sirolimus use (hazard ratio [HR], 5.1; 95% CI, 1.8 to 14.2; P = .002) and RIC regimen with Flu/Bu2 ± ATG (HR, 34; 95% CI, 4.5 to 252; P < .001) or other (HR, 32; 95% CI, 3.9 to 257; P = .001) compared with Flu/Bu1 ± ATG. Rising serum tacrolimus or sirolimus levels, new acute kidney injury, and increasing platelet transfusion requirements were significant early predictors of onset in the week preceding prior VOD/SOS diagnosis. When compared with a previously published cohort of 76 patients with VOD/SOS who developed VOD/SOS after myeloablative HCT in the same time period, VOD/SOS after RIC occurred later and was associated with a lower peak bilirubin level and better overall survival. The variability in presenting features for RIC VOD/SOS highlights the importance of maintaining a high index of suspicion for this entity in RIC HCT.

TBH score: a new model to predict and prevent severe liver damage after chemotherapy for cancer patients

Purpose

To explore a quantitative predictive model for the risk of chemotherapy-induced severe liver damage (CISLD).

Materials and methods

In total, 3870 consecutive cancer patients initially treated with chemotherapy were retrospectively collected and randomly assigned to a training (n=2580) or internal validation (n=1290) set in a 2:1 ratio to construct and validate the model. Additional external validation was performed using another data set (n=413). A total of 486 patients were prospectively enrolled to assess the clinical significance of the model. CISLD was defined as grade ≥3 hepatotoxicity.

Results

CISLD was found in 255 (9.9%), 128 (9.9%) and 36 (8.7%) patients in the training, internal and external validation sets, respectively. Serum triglyceride, body mass index and history of hypertension formed the basis of the score model. Patients could be stratified into low, intermediate and high-risk groups with <10%, 10–30% and >30% CISLD occurrence, respectively. This model displayed a concordance index (C-index) of 0.834 and was validated in both the internal (C-index, 0.830) and external (C-index, 0.817) sets. The incidence of CISLD was significantly reduced in those who received preventive hepatoprotective drugs compared to those who did not among patients assessed as the intermediate risk group (8.9% vs 17.5%, p=0.042) and the high risk group (15.6% vs 55.8%, p=0.043).

Conclusions

The new score model can be used to accurately predict the risk of CISLD in cancer patients undergoing chemotherapy. Clinically, this can be translated into a reference tool for oncologists in the clinical decision-making process before chemotherapy to provide appropriate prevention and interventions for patients with a high risk of CISLD.

Clinical characteristics and treatment of pyrrolizidine alkaloid-related hepatic vein occlusive disease

BACKGROUND AND AIMS

Hematopoietic stem cell transplantation related hepatic vein occlusive disease (HSCT-HVOD) has been researched extensively; however, little is known about the clinical features and treatment of pyrrolizidine alkaloid-induced HVOD (PA-HVOD). This retrospective single centre study examined the clinical and laboratory characteristics of 108 patients with acute PA-HVOD and explored the efficacy of anticoagulation and TIPS therapy.

METHODS

The study included 108 consecutive patients with PA-HVOD between July 2008 and June 2016. The clinical manifestations and the results of laboratory and imaging tests were evaluated. The survival rates of patients treated with different approaches were recorded.

RESULTS

Serum total bilirubin was <34.2 μmol/L (2 mg/dL) in approximately 40% of patients. More than 90% of patients were presented with hepatomegaly, uneven liver perfusion in the balance phase, compressive stenosis of the hepatic segmental inferior vena cava and decreased peak velocity of portal vein blood flow. Severe portal hypertension was observed in all patients undergoing HVPG examination or TIPS operation. Anticoagulation therapy with low molecular weight heparin combined with warfarin was significantly more effective than liver protection and supportive therapy, and TIPS further improved the prognosis of patients who did not respond to anticoagulation therapy. The total effective rate of the anticoagulation-TIPS ladder therapeutic strategy was 91%.

CONCLUSIONS

Patients with PA-HVOD had different characteristics than those with HSCT-HVOD. Anticoagulation and TIPS treatment may be effective for patients with PA-HVOD.

Loss of NLRP3 Function Alleviates Murine Hepatic Graft-versus-Host Disease

NLRP3 is associated with multiple risks in graft-versus-host disease, though unifying principles for these findings remain largely unknown. To explore the effects and mechanisms of the absence of NLRP3 function on hepatic graft-versus-host-disease, we established an allogeneic hematopoietic cell transplantation mice model by infusing bone marrow mononuclear cells and spleno-T cells of the BALB/c mouse into either NLRP3 knockout (NLRP3^-/- ) or wild-type C57BL/6 mice. Elevated inflammatory cell infiltration, liver fibrosis, and secretions of alanine aminotransferase (ALT) and aspartate transaminase (AST), together with weight loss, were observed in C57BL/6 recipients after transplantation. However, moderate injury pathology was detected in the liver of NLRP3^-/- recipients at day 14, which gradually improved over time. Likewise, proinflammatory cytokine IL-1β, a downstream effecter of NLRP3 inflammasome activation, showed significantly lower expression (P < .05) in the liver of NLRP3^-/- recipients relative to C57BL/6 recipients at day 7 and day 21. Moreover, compared with C57BL/6 recipients, the expression of both TNF-α and IL-1β were decreased 3-fold and 4.7-fold, respectively, at day 21 in NLRP3^-/- recipients. Interestingly, NLRP1a was expressed at a significantly reduced level in the liver of NLRP3^-/- recipients (P < .001). Furthermore, systemic inflammation was analyzed by measuring the concentration of IL-1β and adenosine triphosphate (ATP) in serum. The concentration of IL-1β achieved a maximum at day 14, then decreased at day 21 and day 28 in NLRP3^-/- recipients. In contrast, the concentration of IL-1β in C57BL/6 recipients gradually increased from day 7 to day 28. ATP levels reduced from day 7 to day 28 in NLRP3^-/- recipients, but were extremely high in C57BL/6 recipients from day 14 to day 28 (P < .01). The decreased levels of P2X7R were connected to less ATP in NLRP3^-/- recipients at day 21 and day 28. In conclusion, NLRP3 knockout in recipients could significantly relieve liver injury after transplantation and block the NLRP3 inflammasome pathway, thus providing a promising strategy for the treatment of graft-versus-host disease prophylaxis.

Acute phase after haematopoietic stem cell transplantation

The transplantation of allogeneic or autologous haematopoietic stem cells is an established treatment for many malignant and non-malignant diseases of the bone marrow. Intensive cytoreductive regimens administered before transplantation induce prolonged and severe cytopenia of all haematopoietic lineages. Thrombocytopenia leads to an increased risk of bleeding, which may be further aggravated by consumption of plasmatic factors as a result of tumour lysis or after antibody administration. At the same time, patients after transplantation are also at increased risk of thrombotic complications. Endothelial damage induced by radio-and chemotherapy, indwelling catheters, prolonged immobilization and a high incidence of systemic infection all contribute to the frequent occurrence of thromboembolic events in this population.

This review discusses the incidence and risk factors for haemorrhagic and thrombotic complications after stem cell transplantation. Special emphasis is given to complications occurring specifically in the context of transplantation such as diffuse alveolar haemorrhage, haemorrhagic cystitis, veno-occlusive disease, and transplant associated microangiopathy.

Defibrotide for the treatment of sinusoidal obstruction syndrome: evaluation of response to therapy and patient outcomes

PURPOSE

Defibrotide is an agent used to treat sinusoidal obstruction syndrome (SOS/VOD) in patients undergoing haemopoietic stem cell transplantation. The aim of this study was to evaluate the effectiveness of defibrotide used within institutional guidelines for the treatment of SOS/VOD in patients undergoing haemopoietic stem cell transplantation (HSCT).

METHODS

Data for 23 patients was retrospectively reviewed to evaluate the effectiveness of defibrotide and the utility of response criteria to direct therapy as specified within institution guidelines. Patients met institutional criteria for a diagnosis of SOS/VOD based on predominantly Baltimore criteria and received defibrotide. Stabilisation or improvement in symptoms and biochemical markers was required for continuation of therapy with defibrotide.

RESULTS

Overall, 14 patients responded to therapy. Survival at day 100 post HSCT was 70%. Median serum (total) bilirubin concentrations in all evaluable patients had decreased at days 5 and 10 (p < 0.001). There was a proportional reduction in median weight of 4% by day 5 and 6.6% by day 10 (p < 0.001). On cessation of defibrotide, there was a decrease in the proportion of patients exhibiting hepatomegaly (p = 0.02), ascites (p < 0.01) and requiring oxygen supplementation (p < 0.01), with 70% survival at day 100 post HSCT.

CONCLUSION

Defibrotide to treat SOS/VOD and continued based on attainment of early response was effective management of this condition. Defibrotide should be considered in any consensus protocol providing guidance on the management of SOS/VOD, with future studies considered to assess appropriate time points for response to therapy during treatment.

The Impact of Toxicities on First-Year Outcomes after Ex Vivo CD34+-Selected Allogeneic Hematopoietic Cell Transplantation in Adults with Hematologic Malignancies

Factors that impact first-year morbidity and mortality in adults undergoing myeloablative allogeneic hematopoietic cell transplantation with ex vivo CD34⁺ selection have not been previously reported. We assessed all toxicities ≥ grade 3 from the start of conditioning to date of death, relapse, or last contact in 200 patients during the first year after transplantation, identifying 1885 individual toxicities among 17 organ-based toxicity groups. The most prevalent toxicities in the first year were of infectious, metabolic, hematologic, oral/gastrointestinal, hepatic, cardiac, and pulmonary etiologies. Renal complications were minimal. Grades II to IV and III and IV acute GVHD at day 100 were 11.5% and 3%, respectively. In separate multivariate models, cardiovascular, hematologic, hepatic, neurologic, pulmonary, and renal toxicities negatively impacted nonrelapse mortality (NRM) and overall survival during the first year. A higher-than-targeted busulfan level, patient cytomegalovirus seropositivity, and an Hematopoietic Cell Transplantation-Specific Comorbidity Index of ≥3 were associated with increased risk of NRM and all-cause death. Ex vivo CD34⁺ selection had a favorable 1-year OS of 75% and NRM of 17% and a low incidence of sinusoidal obstruction syndrome. These data establish a benchmark to focus efforts in reducing toxicity burden while improving patient outcomes.

Hepatic Sinusoidal Obstruction Syndrome Induced by Non-transplant Chemotherapy for Non-Hodgkin Lymphoma

Hepatic sinusoidal obstruction syndrome (SOS), a serious complication that mainly occurs after hematopoietic-stem cell transplantation (HSCT), is caused by damage to the sinusoidal endothelial cells after the obstruction of the sinusoid. Recently, hepatic SOS was reported to occur after non-HSCT chemotherapies. This report describes a patient who experienced hepatic SOS after non-HSCT chemotherapy for non-Hodgkin lymphoma. A liver biopsy showed the slight dilatation of the hepatic sinusoid, which may be indicative of hepatic SOS. Hepatic SOS should be included in the differential diagnosis of patients with severe liver injury following the administration of chemotherapy regimens that are toxic to the vascular endothelial cells.

Defibrotide in Severe Sinusoidal Obstruction Syndrome: Medicine and Economic Issues

In Europe, Defitelio (defibrotide) has a Market Authorization in curative treatment of severe sinusoidal obstruction syndrome (SOS) but not in prophylaxis (2013). In France, defibrotide has had a compassionate-use program since 2009. Today, the high cost of defibrotide remains a major hurdle for hospital budgets. Medicine and economic issues were evaluated for the 39 hospitals of the French Public Assistance-Hospitals of Paris (AP-HP). We analyzed literature reviews, consumption, and expenditures through AP-HP data in 2014 and patient profiles with defibrotide in the corresponding diagnostic-related groups (DRGs) and consulted a board of hematologists. Finally, 18 publications were selected. Between 2011 and 2014 consumption increased to €5.2M. In 2014, 80 patients receiving defibrotide were mainly ascribed to the DRG "hematopoietic stem cell transplantation" levels 3 or 4. The tariffs attributed to drugs (€3544 to 4084) cover a small part of treatment costs (€97,524 for an adult). French experts thus recommended a harmonization of indications in prophylaxis (off-label use), improvement of pretransplant care, and optimization of the number of vials used. The economic impact led experts to change their practices. They recommended the restriction of defibrotide use to SOS curative treatment and to high-risk situations in prophylaxis.

Defibrotide for the management of sinusoidal obstruction syndrome in patients who undergo haemopoietic stem cell transplantation

Sinusoidal obstruction syndrome, previously known as veno-occlusive disease (VOD/SOS), is a complication in patients undergoing haemopoietic stem cell transplantation (HSCT). Severe VOD/SOS, including progression to multi-organ failure, has resulted in a mortality of greater than 80%. Defibrotide's varying pharmacological actions, particularly on endothelial cells, make it is a useful agent to consider for prophylaxis and treatment of VOD/SOS. Barriers to its routine use include the high acquisition cost and the fact that neither the oral or parenteral formulations are licensed products in many countries at this time. This review summarises available literature on the use of defibrotide in the management of VOD/SOS. Publications consist predominantly of single centre cohort studies and case series. Available evidence indicates that defibrotide is effective in the management of VOD/SOS. Using defibrotide prophylaxis should also be considered, especially in the paediatric setting, where there are available results from a large, open label, randomized controlled trial. Patient outcome data from the larger studies and compassionate programs can inform consensus recommendations on dosing regimen and criteria for the treatment of VOD/SOS with defibrotide in the adult population. The reviewed literature indicates an effective and safe dose for treatment is 25mg/kg/day, continued for at least 14days or until complete response is achieved. Further studies are required to determine the optimal dose and duration of treatment in both paediatric patients and adults. Recent recommendations and a phase 3 trial using historical controls indicate that defibrotide should be included as a pharmacotherapy option in protocols guiding management of VOD/SOS.

Veno-occlusive disease nurse management: development of a dynamic monitoring tool by the GITMO nursing group

Veno-occlusive disease (VOD) is a complication arising from the toxicity of conditioning regimens that have a significant impact on the survival of patients who undergo stem cell transplantation. There are several known risk factors for developing VOD and their assessment before the start of conditioning regimens could improve the quality of care. Equally important are early identification of signs and symptoms ascribable to VOD, rapid diagnosis, and timely adjustment of support therapy and treatment. Nurses have a fundamental role at the stages of assessment and monitoring for signs and symptoms; therefore, they should have documented skills and training. The literature defines nurses’ areas of competence in managing VOD, but in the actual clinical practice, this is not so clear. Moreover, there is an intrinsic difficulty in managing VOD due to its rapid and often dramatic evolution, together with a lack of care tools to guide nurses. Through a complex evidence-based process, the Gruppo Italiano per il Trapianto di Midollo Osseo (GITMO), cellule staminali emopoietiche e terapia cellulare nursing board has developed an operational flowchart and a dynamic monitoring tool applicable to haematopoietic stem cell transplantation patients, whether they develop this complication or not.

Safety of peritoneal and pleural drain placement in pediatric stem cell transplant recipients with severe veno-occlusive disease

Hepatic VOD (veno-occlusive disease) is a serious complication of HSCT (hematopoietic stem cell transplantation) and has historically been associated with high mortality. This obstruction to hepatic flow often results in fluid collections in the peritoneal and pleural cavities. Catheter placement to drain ascites or pleural fluid may reduce intra-abdominal hypertension and/or improve respiratory parameters. The safety of these interventions among critically ill, immunocompromised children is unknown. Among 32 HSCT recipients (2000-2012) with severe VOD, we assessed the primary outcome of procedural complication from peritoneal drain placement. Twenty-four (75%) patients underwent peritoneal drain placement. No patient sustained visceral perforation or hemorrhage with drain placement. Overall mortality was 47% (n = 15). The procedure was not associated with increased overall mortality (p > 0.99). Eight (25%) peritoneal drains required replacement for malfunction. Of 24 patients with peritoneal drains, one (4%) patient had a positive culture from ascitic fluid. Eight (25%) patients underwent pleural drain placement. No pleural drain-related procedural complication or infection occurred. Four (50%) of the eight patients with pleural drains had de-escalation in oxygen requirement at drain removal, compared to time of placement. In this study, peritoneal and pleural drains were safe interventions for children with severe VOD.

Defibrotide for the Treatment of Hepatic Veno-Occlusive Disease: Final Results From the International Compassionate-Use Program

Hepatic veno-occlusive disease, also called sinusoidal obstruction syndrome (VOD/SOS), is an unpredictable and potentially fatal complication of hematopoietic cell transplantation (HCT) or nontransplantation-associated chemotherapy/radiotherapy. In cases of severe hepatic VOD/SOS, typically defined by associated multiorgan failure (MOF, also known as multiorgan dysfunction), mortality exceeds 80%. Preclinical and early clinical data have provided a rationale for defibrotide treatment in hepatic VOD/SOS. Based on this evidence and in recognition of the dismal prognosis for these patients, defibrotide was made available through an international multicenter compassionate-use program conducted from December 1998 to March 2009. Physicians participating in the program voluntarily provided demographic and outcome data for patients given defibrotide. Efficacy and safety analyses were performed using the data received for 710 treated patients. Defibrotide was given at 10, 25, 40, 60, or 80 mg/kg/day for a median of 15 days (range, 1 to 119 days). By Kaplan-Meier analysis, the estimated overall day +100 survival was 54% (58% in the 25 mg/kg/day dose group). Adverse events (AEs) were reported in 53% of patients. The most common AEs were MOF, progression of hepatic VOD/SOS, sepsis, and graft-versus-host disease, which were consistent with the AEs expected for this patient population. No clinically meaningful trends in AEs were identified by gender, age, or dose group. Safety and efficacy resultswere consistent with prior studies of defibrotide in hepatic VOD/SOS, and subgroup analyses lend support to the use of the 25 mg/kg/day dose.

Blockage of caspase-1 activation ameliorates bone marrow inflammation in mice after hematopoietic stem cell transplantation

Conditioning regimens before hematopoietic stem cell transplantation (HSCT), cause damage to bone marrow and inflammation. Whether inflammasomes are involved in bone marrow inflammation remains unclear. The study aims to evaluate the role of inflammasomes in bone marrow inflammation after HSCT. On days 7, 14, 21 and 28 after HSCT, mice were sacrificed for analysis of bone marrow inflammation, pro-inflammatory cytokines secretion, inflammasomes expression and caspase-1 activation. Bone marrow inflammation with neutrophils and macrophages infiltration was observed after HSCT. Secretion of IL-1β, IL-18, TNF-α and IL-6 were elevated, with increased caspase-1 activation and inflammasomes expression. Caspase-1 inhibitor administration after HSCT significantly reduced infiltration of neutrophils and macrophages into bone marrow and increased the numbers of megakaryocytes and platelets. In conclusion, inflammasomes activation is involved in bone marrow inflammation after HSCT and caspase-1 inhibition attenuates bone marrow inflammation and promoted hematopoietic reconstitution, suggesting targeting caspase-1 might be beneficial for improving HSCT outcomes.

Hepatic Veno-Occlusive Disease after Hematopoietic Stem Cell Transplantation: Risk Factors and Stratification, Prophylaxis, and Treatment

Hepatic veno-occlusive disease (VOD), also known as sinusoidal obstruction syndrome (SOS), can develop in a subset of patients, primarily after myeloablative hematopoietic stem cell transplantation, but it also may occur after reduced-intensity conditioning. Severe VOD/SOS, typically characterized by multiorgan failure, has been associated with a mortality rate greater than 80%. Therefore, an accurate and prompt diagnosis of VOD/SOS is essential for early initiation of appropriate therapy to improve clinical outcomes. Moreover, some studies have support the use of prophylaxis for patients who are at high risk of developing VOD/SOS. This review summarizes risk factors associated with development of VOD/SOS, including pretransplantation patient characteristics and factors related to stem cell transplantation, that can facilitate patient stratification according to risk. The incidence of VOD/SOS, clinical features, and diagnostic criteria are reviewed. Data on emerging treatment strategies for patients with VOD/SOS are discussed in the context of recent treatment guidelines. Additionally, options for prophylaxis in individuals who are at increased risk are presented. Although historically only those patients with moderate to severe VOD/SOS have been treated, early therapy and prophylaxis may be appropriate for many patients and may have the potential to improve patients' outcomes and survival, including for those with nonsevere disease.

Autologous hematopoietic cell transplantation: an update for clinicians

High-dose chemotherapy followed by transplantation of autologous hematopoietic progenitor cells has a proven track record of safety and efficacy in hematological malignancies and select solid tumors. The near-universal use of peripheral blood stem cells as source for autografts, routine growth factor support, and antimicrobial prophylaxis post transplantation has improved the safety of this procedure. However, the advent of highly active novel therapies in the last few years warrants reappraisal of the role of autologous transplantation in the therapeutic armamentarium of malignant disorder. This review summarizes the current role of autologous transplantation for hematological malignancies, discusses modern standards for patient selection, and highlights long-term care issues of transplant survivors from an internist's perspective. Role of tumor purging in autologous transplantation, novel transplant conditioning regimens, and post-transplant therapies to prevent disease relapse are reviewed.

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.

Complications of allogeneic hematopoietic stem cell transplantation

Infection, graft-versus-host disease (GVHD), and to a lesser extent sinusoidal obstructive syndrome (SOS) represent the major causes of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation (AHSCT). During the last decade, progress in prevention and treatment of these complications led to improvement in the outcome of these patients. Despite the fact that nonmyeloablative regimens have been increasingly used in elderly patients and in patients with co-morbidities, the nonrelapse related mortality remains a challenge and long-term follow-up is required. The objective of this manuscript is to provide an updated concise review of the complications of AHSCT and of the available treatment interventions.

Experiences of t-PA use in moderate-to-severe hepatic veno-occlusive disease after hematopoietic SCT: is it still reasonable to use t-PA?

Hepatic veno-occlusive disease (VOD) remains one of the most severe complications of hematopoietic SCT (HSCT). Anticoagulation and thrombolytic therapies using tissue-plasminogen activator (t-PA) have been used, but are reported to be ineffective and are associated with significant bleeding complications. We analyzed 56 moderate-to-severe post HSCT hepatic VOD cases treated with t-PA. We analyzed clinical outcomes according to the maximal daily dose of t-PA (t-PAmax) and the severity of VOD. Patients were stratified by t-PAmax10 mg (n=37) vs t-PAmax>10 mg (n=19). A higher t-PAmax was associated with increased mortality. Bleeding complications were more likely at higher t-PAmax in both moderate and severe VOD (P=0.036, 0.063), especially if patients had concomitant use of anticoagulants (36.4% vs 13.3%). In moderate VOD, the response rate was 86.4% for t-PAmax10 mg/day and 80% for t-PAmax>10 mg compared with 33.3% and 7.1%, respectively, for severe VOD (P=0.106). The 5-year OS in moderate and severe VOD was 49% and 7%, respectively, and it was 32% for t-PAmax10 mg and 18% for t-PAmax>10 mg. Our data demonstrate that lower bleeding complications and bleeding-related deaths may result from strict limitations on the t-PAmax without concomitant use of anticoagulation therapy. However, the overall response and survival outcomes should be re-evaluated by a well-validated study in the future.

Kidney complications of hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) exposes a patient's kidneys to a unique combination of challenges, including high-dose radiation, anemia, chemotherapeutic agents, graft-versus-host disease, opportunistic infections, attenuated and altered immunologic responses, fluid and electrolyte imbalances, and extensive courses of antimicrobial agents. Since the inception of HSCT in the 1950s, there has been increasing interest in defining, determining, and managing the kidney complications that accompany this procedure. In this article, we review the common causes of acute kidney injury and chronic kidney disease that occur with HSCT, including HSCT-associated thrombotic microangiopathy, a distinct cause of chronic kidney disease with a multifactorial cause previously known as bone marrow transplant nephropathy or radiation nephropathy. Additionally, we review other kidney complications, including calcineurin inhibitor nephrotoxicity and chronic graft-versus-host disease-associated glomerulonephritis, that develop post-HSCT. Critically, due to its grave prognosis, it is important to identify HSCT-associated thrombotic microangiopathy early, as well as distinguish it from the other causes of chronic kidney disease.

Defibrotide for the treatment of hepatic veno-occlusive disease in children after hematopoietic stem cell transplantation

Hepatic veno-occlusive disease (VOD) is a serious complication of stem cell transplantation in children. VOD is characterized by rapid weight gain, hepatomegaly, hyperbilirubinemia and ascites. The pathogenesis of VOD is thought to involve chemotherapy and radiation-induced damage to the sinusoidal endothelium, resulting in endothelial injury, microthrombosis, subendothelial damage and cytokine activation. These processes lead to concomitant progressive hepatocellular dysfunction and subsequent fluid retention and renal impairment. Severe VOD is typically associated with multiorgan failure and high mortality. A number of possible strategies for the prevention and/or treatment of VOD in children have been investigated. The most promising agent to date is defibrotide, a novel polydeoxyribonucleotide with fibrinolytic properties but no major bleeding risk. Numerous studies, including Phase II/III trials, have shown clinical benefit in pediatric patients with the use of defibrotide treatment and prophylaxis. This review discusses VOD in children and focuses on therapeutic options, including defibrotide, in this patient population.

Antineoplastic agent busulfan regulates a network of genes related to coagulation and fibrinolysis

Purpose Hepatic veno-occlusive disease (HVOD) is one of the major complications following hematopoietic stem cell transplantation (HSCT). Although high-dose busulfan is associated with the development of HVOD, the underlying molecular mechanisms are still unknown.Methods Transcriptional gene regulation by busulfan was profiled using Affymetrix GeneChip® Human Genome U133 Plus 2.0 arrays. Messenger RNA (mRNA) expression of regulated genes was assessed by TaqMan real-time polymerase chain reaction (PCR), and protein expression and secretion was determined by enzyme-linked immunosorbent assay (ELISA)in cell supernatants, lysates, and patient plasma.Results Plasma levels of plasminogen activator inhibitor(PAI)-1 significantly increased 48 h after starting busulfan treatment IV in children preconditioned for HSCT. In vitro,busulfan significantly induced plasminogen activator inhibitor-1 (PAI-1) expression in endothelium-like ECV304 cells in a concentration- and time-dependent manner. Comparative transcriptional profiling of busulfan-treated and control ECV304 cells identified differential expression of genes related to coagulation and fibrinolysis, including tissue factor, tissue factor pathway inhibitor-1, protein S, thrombospondin-1, urokinase receptor, and PAI-1, as well as activin A and transforming growth factor beta 1 (TGF-β1). Ingenuity pathway analysis (IPA) suggested TGF-β1 as a central modulator of gene regulation by busulfan. Consequently, expression of tissue factor, urokinase receptor, and PAI-1 mRNA and PAI-1 protein secretion induced by busulfan were significantly reduced by the activin A/TGF-β1 inhibitor SB 431542 in ECV304 and primary endothelial cells.Conclusions This is the first report that directly relates busulfan exposure to antifibrinolytic activity by PAI-1 and hypercoagulation possibly mediated by members of the TGF-β1 family. This suggests further research to evaluate activin A and TGF-β1 as potential targets for HVOD treatment.

Thrombosis in stem cell transplantation

Hemostatic changes and thrombotic events are frequent in patients undergoing stem cell transplantation. Arterial and venous thromboses are major causes of morbidity and mortality. Thrombotic complications can be classified into four groups including: catheter-related thrombosis, venous thromboembolic (VTE) events, sinusoidal obstructive syndrome (SOS)/veno-occlusive disease, and transplant-associated thrombotic microangiopathy (TAM). The incidence of catheter-related thrombosis is 8-20% in patients undergoing autologous hematopoietic stem cell transplantation (HSCT), and the incidence is low in syngeneic and allogeneic transplant patients. Venous duplex Doppler ultrasound, venogram, and computed tomography scan are required to visualize the venous thrombus. The treatment should be aimed at the prevention of pulmonary embolism, the avoidance of thrombus extension, and the preservation of catheter patency. Patients undergoing HSCT may have risk factors for VTE including underlying malignancy, traumatic brain injury, prolonged hospitalization, administration of conditioning regimens, and central venous catheters. Important risk factors are presence of history of VTE and graft-versus-host disease. One-year incidence of symptomatic VTE is 3.7%. SOS, also known as veno-occlusive disease, is a serious liver disease, seen in approximately 50-60% of HSCT patients. The mortality rate from the severe form of SOS is 84.3% and majority of the patients have multi-organ failure. The frequency is quite low after autologous transplantation. Risk factors for SOS include pre-existing hepatic damage, previous high-dose chemotherapy and abdominal irradiation, female gender and donor-recipient human leukocyte antigen disparity. Cyclophosphamide and busulphan are the most common agents with the highest incidence and fatal SOS. Histopathologic features of SOS include dilatation of sinusoids, necrosis of perivenular hepatocytes, and obstruction of small intrahepatic central venules by microthrombi and fibrin deposition. Signs of SOS usually occur within first 30 days after HSCT including hyperbilirubinemia, hepatomegaly, ascites, and weight gain. Symptoms of liver failure, including encephalopathy, coagulopathy, and renal failure will appear in severe form. A hepatic venous pressure gradient above 10 mmHg is highly specific for SOS. Early use of defibrotide has been shown to be effective in the treatment of high-risk SOS. TAM is a distinct, infrequent, and significant life-threatening complication of HSCT. TAM is seen in the range of 0·5-76% and was reported to be 10-25% in patients undergoing allogeneic HSCT with a mortality rate around 50%. It can also be seen after autologous HSCT and mainly affects the glomerular capillaries. There has been no standard therapy for TAM. Few case series reported good response to rituximab and high-dose corticosteroids were used with limited success. Trials with complement inhibitors such as eculizumab are currently underway.

Safety and efficacy of defibrotide for the treatment of severe hepatic veno-occlusive disease

Hepatic veno-occlusive disease (VOD), also known as sinusoidal obstruction syndrome, is a potentially life-threatening complication of chemotherapeutic conditioning used in preparation for hematopoietic stem-cell transplantation (SCT). VOD may occur in up to 62% of patients undergoing SCT, with onset generally within the first month after SCT. In severe cases, 100-day mortality is in excess of 80%. Current management consists of best supportive care, with no agents to date approved for treatment in the USA or the EU. Defibrotide, a polydisperse oligonucleotide, has been shown in phase II and III trials to improve complete response and survival in patients undergoing SCT with severe VOD. This article reviews our current understanding of VOD, and examines recent clinical findings on defibrotide for the treatment and prophylaxis of VOD.

Contribution of fibrinolytic tests to the differential diagnosis of veno-occlusive disease complicating pediatric hematopoietic stem cell transplantation

BACKGROUND

Veno-occlusive disease (VOD) is a major complication following hematopoietic stem cell transplantation (HSCT). Its diagnosis is based on clinical criteria, which have a limited sensitivity. Increased plasminogen activator inhibitor-1 (PAI-1) levels have been suggested as a marker of VOD. We aimed to prospectively evaluate how the fibrinolytic parameters behaved to discriminate VOD from other liver disorders occurring after HSCT in a pediatric population.

PROCEDURES

A total of 195 HSCT were performed on 161 children and VOD complicated 11 cases (6.8%). Alanine aminotransferase, total bilirubin, PAI-1 antigen (PAI-1:Ag) and activity, t-PA antigen, D-dimer, prothrombin time, activated partial thromboplastin time, antithrombin, fibrinogen, and platelet counts were measured in 105 HSCT before and then weekly for 1 month after HSCT.

RESULTS

An early, significant increase in the fibrinolytic parameters was seen in patients who developed VOD, even before VOD was diagnosed clinically, by comparison with patients without complications or those with non-VOD liver disorders. The combined increase in bilirubin, D-dimer, and PAI-1:Ag levels beyond the normal range distinguished VOD cases from other liver complications with a high sensitivity and specificity.

CONCLUSIONS

Our study demonstrates that fibrinolytic tests can help diagnose VOD after HSCT in the pediatric population.

Incidence and risk factors for early hepatotoxicity and its impact on survival in patients with myelofibrosis undergoing allogeneic hematopoietic cell transplantation

Allogeneic hematopoietic cell transplantation (HCT) is commonly associated with hepatic complications. Patients with myelofibrosis (MF) often develop liver dysfunction in the early posttransplantation period; however, this has not yet been studied in a systematic fashion. We retrospectively evaluated 53 patients with MF who underwent HCT to assess the prevalence of acute liver toxicity and risk factors and the impact on survival. We compared the prevalence of acute hepatic complications in that group and a matched control group of 53 patients with myelodysplastic syndrome (MDS). In the MF group, during the first 6 weeks after HCT, the incidence of mild (34.2-102.6 μM), moderate (102.6-342 μM), and severe (>342 μM) hyperbilirubinemia was 34%, 40%, and 4%, respectively (normal, <22 μM). The incidence of mild/moderate transaminitis (2-10 times the upper limit of normal) was 23%, and that of severe transaminitis (>10 times the upper limit of normal) was 6%. Veno-occlusive disease as defined by the Baltimore criteria was observed in 19 patients (36%) in the MF group. Compared with MDS, MF was associated with a significantly higher incidence of moderate/severe hyperbilirubinemia (44% versus 21%; P = .02) and veno-occlusive disease (36% versus 19%; P = .05). A history of portal hypertension, biopsy-proven hepatic iron overload, or splanchnic vein thrombosis was a strong predictor of moderate/severe hyperbilirubinemia (P = .02). Acute hepatocellular injury with moderate/severe hyperbilirubinemia or transaminitis was associated with inferior survival at 12 months (P = .02) in the MF group. We conclude that patients with MF are at significant risk of early hepatotoxicity after HCT, which is associated with an adverse impact on survival.