Hepatic veno-occlusive disease after hematopoietic stem cell transplantation: Prophylaxis and treatment controversies

Epidemiology, Risk Factors, and Clinical Outcomes of AKI in Pediatric Hematopoietic Stem Cell Transplant Patients

Key Points

Background

AKI is a common complication in pediatric patients undergoing hematopoietic stem cell transplantation (HSCT), with a reported prevalence ranging from 68% to 84%. Few multicenter pediatric studies comprehensively assess the epidemiologic associations and clinical outcomes associated with AKI development.

Methods

An observational, retrospective analysis was conducted using an aggregated electronic health record data platform. The study population consisted of pediatric patients (age <18 years) who underwent HSCT over a 20-year period. The study groups consisted of patients with an encounter diagnosis of AKI (n=713) and those without AKI (n=4455). Both groups were propensity matched for age, sex, race, prior cancer diagnosis, and other comorbidities. End points were incidence, mortality risk, clinical outcomes, and prevalence of dialysis dependence. Competing risks analysis, Cox proportional hazard analyses, Kaplan–Meier survival curves, and incidence/prevalence rates were calculated.

Results

After matching, 688 patients were identified. Cumulative incidence of AKI diagnosis post-HSCT was 13.7%. Hypertensive disease, calcineurin inhibitors, and vancomycin were the most prevalent risk factors for AKI, with calcineurin inhibitors showing the highest cumulative incidence (21.6%). Patients with AKI with hypertensive disease had a survival probability of 63.9% at 30 days, followed by calcineurin inhibitors (64.4%) and vancomycin (65.9%). Patients with AKI were 1.7 times more likely to experience composite hospitalization and/or mortality at 30 days. At 365 days post-HSCT, patients with AKI had higher rates of all-cause emergency department visits, intensive care unit admissions, and mechanical ventilation compared with non-AKI. Of patients who developed AKI, the prevalence of dialysis dependence has nearly tripled since 2014.

Conclusions

The findings highlight a strong association between specific risk factors, such as hypertension, calcineurin inhibitor use, and vancomycin use, with increased mortality and adverse clinical outcomes in patients with AKI after HSCT. These results emphasize the need for preventative actions such as 24-hour BP monitoring and discontinuation of potential nephrotoxic medications.

Constructing training set using distance between learnt graphical models of time series data on patient physiology, to predict disease scores

Interventional endeavours in medicine include prediction of a score that parametrises a new subject's susceptibility to a given disease, at the pre-onset stage. Here, for the first time, we provide reliable learning of such a score in the context of the potentially-terminal disease VOD, that often arises after bone marrow transplants. Indeed, the probability of surviving VOD, is correlated with early intervention. In our work, the VOD-score of each patient in a retrospective cohort, is defined as the distance between the (posterior) probability of a random graph variable-given the inter-variable partial correlation matrix of the time series data on variables that represent different aspects of patient physiology-and that given such time series data of an arbitrarily-selected reference patient. Such time series data is recorded from a pre-transplant to a post-transplant time, for each patient in this cohort, though the data available for distinct patients bear differential temporal coverage, owing to differential patient longevities. Each graph is a Soft Random Geometric Graph drawn in a probabilistic metric space, and the computed inter-graph distance is oblivious to the length of the time series data. The VOD-score learnt in this way, and the corresponding pre-transplant parameter vector of each patient in this retrospective cohort, then results in the training data, using which we learn the function that takes VOD-score as its input, and outputs the vector of pre-transplant parameters. We model this function with a vector-variate Gaussian Process, the covariance structure of which is kernel parametrised. Such modelling is easier than if the score variable were the output. Then for any prospective patient, whose pre-transplant variables are known, we learn the VOD-score (and the hyperparameters of the covariance kernel), using Markov Chain Monte Carlo based inference.

Acute kidney injury in pediatric hematopoietic cell transplantation: critical appraisal and consensus

Hematopoietic cell transplantation (HCT) is a common therapy for the treatment of neoplastic and metabolic disorders, hematological diseases, and fatal immunological deficiencies. HCT can be subcategorized as autologous or allogeneic, with each modality being associated with their own benefits, risks, and post-transplant complications. One of the most common complications includes acute kidney injury (AKI). However, diagnosing HCT patients with AKI early on remains quite difficult. Therefore, this evidence-based guideline, compiled by the Pediatric Continuous Renal Replacement Therapy (PCRRT) working group, presents the various factors that contribute to AKI and recommendations regarding optimization of therapy with minimal complications in HCT patients.

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.

Refined ultrasonographic criteria for sinusoidal obstruction syndrome after hematopoietic stem cell transplantation

Hepatic sinusoidal obstruction syndrome (SOS)/veno-occlusive disease is a life-threatening complication after hematopoietic stem cell transplantation (HSCT). We previously reported the efficacy of the Hokkaido Ultrasonography (US)-based scoring system (HokUS-10) for US findings. To establish easier-to-use criteria, we retrospectively evaluated US findings from 441 patients, including 30 patients with SOS using the HokUS-10 scoring system. Using logistic regression analysis, we established the novel diagnostic criteria HokUS-6. In the presence of ascites, US diagnosis was made in the presence of two of the following 6 parameters: moderate amount of ascites, the appearance of a paraumbilical vein blood flow signal, gallbladder wall thickening, portal vein dilatation, portal vein velocity decrease, and hepatic artery resistive index increase. The AUC, sensitivity, and specificity of HokUS-6 were 0.974 (95% confidence interval 0.962-0.990), 95.2%, and 96.9%, respectively. The scores were significantly higher in patients with severe SOS than in those with non-severe SOS (p = 0.013). Furthermore, the scores before HSCT were significantly higher in patients who developed SOS than in controls (p = 0.001). The HokUS-6 is an easy and useful way to diagnose and identify the risk of SOS.

Reliability of an ultrasonographical scoring system for diagnosis of sinusoidal obstruction syndrome/veno-occlusive disease in patients with hematopoietic stem cell transplantation

PURPOSE

Sinusoidal obstruction syndrome (SOS)/hepatic veno-occlusive disease (VOD) is a fatal complication after hematopoietic stem cell transplantation. We previously reported the usefulness of an ultrasonographical (US) scoring system, the Hokkaido US-based scoring system consisting of ten parameters (HokUS-10): (1) hepatomegaly in the left lobe and (2) right lobe, (3) dilatation of the main portal vein (PV), (4) hepatofugal flow in the main PV, (5) decreased velocity of the PV, (6) dilatation of the para-umbilical vein (PUV), (7) appearance of blood flow signal in the PUV, (8) gallbladder (GB) wall thickening, (9) ascites, and (10) increased resistive index of the hepatic artery, for the diagnosis of SOS/VOD. However, the reliability of this system among operators remains elusive. Therefore, we prospectively evaluated the reliability of HokUS-10.

METHODS

Twenty-four healthy volunteers and 40 patients with liver dysfunction were enrolled. Inter- and intra-operator reliabilities were analyzed using three sonographers.

RESULTS

The median concordance rate of HokUS-10 among three sonographers and intra-operator in 24 volunteers was 92% (95% CI: 73-98%) and 98% (95% CI: 92-100%), respectively. In all 64 cases, in terms of the reliability between two sonographers for three representative US parameters (amount of ascites, GB wall thickening, and appearance of PUV blood flow signal), the median concordance rate was more than 98% (95% CI: 86-106%).

CONCLUSION

The inter- and intra-reliabilities of HokUS-10 were excellent. Thus, US might be a reliable tool for SOS/VOD diagnosis.

Cost-effectiveness analysis of defibrotide in the treatment of patients with severe veno-occlusive disease/sinusoidal obstructive syndrome with multiorgan dysfunction following hematopoietic cell transplantation in Spain

AIMS

This study evaluated cost-effectiveness of defibrotide vs best supportive care (BSC) for the treatment of hepatic veno-occlusive disease/sinusoidal obstructive syndrome (VOD/SOS) with multiorgan dysfunction (MOD) post-hematopoietic cell transplantation (HCT) in Spain.

MATERIALS AND METHODS

A two-phase Markov model, comprising a 1-year acute phase with daily cycles and a lifetime long-term phase with annual cycles, was adapted to the Spanish setting. The model included a cohort of patients with severe VOD/SOS (defined as VOD/SOS with MOD) post-HCT. For the acute phase, efficacy and VOD/SOS-related length of stay were obtained from a phase 3 defibrotide study (NCT00358501). VOD/SOS-related hospital stays were 7.5 and 23.2 days in defibrotide-treated and BSC patients, respectively. Defibrotide-treated patients spent 30% of their stay in the intensive care unit vs 60% in BSC patients. Assumptions for the long-term phase and utility values were obtained from the literature. Costs were from the Spanish Health System perspective (€2019). Defibrotide cost was based on 25 mg/kg/day over 17.5 days, using local expert opinion. Life-years (LYs), quality-adjusted LYs (QALYs), and costs were estimated over a lifetime horizon, applying a 3% discount rate for costs and outcomes. Sensitivity analyses assessed the robustness of the results.

RESULTS

Defibrotide produced an additional 1.214 QALYs and 1.348 LYs vs BSC, with a total cost of €33,708 more than BSC alone. However, defibrotide resulted in savings up to €16,644/patient for cost of hospital stay. Difference between costs and effective measures led to ratios of €27,757/QALY and €25,007/LY gained. Additional hospital stays had the greatest influence on base-case results. Probabilistic analysis confirmed the robustness of the deterministic results.

LIMITATIONS

Limitations include use of historical controls and assumptions extrapolated from the literature.

CONCLUSIONS

This cost-effectiveness model, adapted to the Spanish setting, showed that defibrotide is a cost-effective alternative to BSC alone in patients with severe VOD/SOS post-HCT.

Early fluctuations in busulfan levels with therapeutic dose monitoring during allogeneic stem cell transplantation: do they matter?

Therapeutic dose monitoring is widely adopted for determination of busulfan (Bu) dose for use as a conditioning regimen. However, while dose adjustments are being incorporated, transient fluctuations of Bu levels may occur. We aim to understand if these fluctuations affect clinical outcomes of these patients. We compared outcomes in patients in whom the absolute dose changes and fluctuation of AUC were ≥ median% versus < median%. Rates of sinusoidal obstructive syndrome, grades 2-4/grades 3-4 acute and chronic graft versus host disease were not different between the two cohorts. The Kaplan-Meier curves for overall survival showed no significant differences. Six patients required >50% dose adjustment and four had a fluctuation in AUC of >50%. One of these patients died of sinusoidal obstruction syndrome and two died of infections. In our study, the transient fluctuations in Bu levels did not affect clinical outcomes; hence obviating the need for test dose strategy.

Novel Ultrasonographic Scoring System of Sinusoidal Obstruction Syndrome after Hematopoietic Stem Cell Transplantation

Sinusoidal obstruction syndrome (SOS)/hepatic veno-occlusive disease (VOD) is a well-documented complication after hematopoietic stem cell transplantation (HSCT). Transabdominal ultrasonography (US) enables the visualization of blood flow abnormalities and is therefore useful for the diagnosis of SOS/VOD. We herein prospectively evaluated accuracy of a novel US diagnostic scoring system of SOS/VOD based on US findings. We carried out US in 106 patients on day 14 and when SOS/VOD was suspected after allogeneic HSCT. Among 106 patients, 10 patients (9.4%) were diagnosed as SOS/VOD by Baltimore or Seattle criteria. According to univariate analysis of 17 US findings (US-17 screening), we established a novel scoring system (HokUS-10) consisting of 10 parameters, such as gallbladder wall thickening, ascites, and blood flow signal in the paraumbilical vein. The sensitivity and specificity were 100% and 95.8%, respectively. Diagnostic performance of the HokUS-10 was significantly better than US-17 screening. In 4 of 10 patients US detection of SOS/VOD preceded to clinical diagnosis. The HokUS-10 scoring system is useful in the diagnosis of SOS/VOD; however, our results should be validated in other cohorts.

Veno-occlusive disease/sinusoidal obstruction syndrome after haematopoietic stem cell transplantation: Middle East/North Africa regional consensus on prevention, diagnosis and management

Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) of the liver is a serious, early complication of haematopoietic stem cell transplantation (HSCT), severe and very severe forms of which are associated with a high mortality rate. A wide variety of patient, disease and treatment-related risk factors for VOD/SOS have been identified. Several bodies have published recommendations for the diagnosis, prevention and management of VOD/SOS following HSCT. A group of regional experts have developed a consensus statement on the diagnosis, prevention and management of VOD/SOS in the Middle East and North Africa region to help in the management of HSCT patients in the region. Risk factors of particular relevance in the region include iron overload in thalassaemia patients, some hereditary metabolic disorders due to consanguinity and infection with hepatitis virus B or C. Recommendations include diagnosis of VOD/SOS based on established clinical criteria, prophylaxis with defibrotide and/or ursodeoxycholic acid in patients at increased risk of VOD/SOS, and treatment with defibrotide for patients with severe/very severe VOD/SOS (and, if clinically indicated, in those with moderate or rapidly progressing VOD/SOS, as per the new European Society for Blood and Marrow Transplantation classification).

Intra- and extracellular plasminogen activator inhibitor-1 regulate effect of vitronectin against radiation-induced endothelial cell death

Plasminogen activator inhibitor-1 (PAI-1) is induced by radiation resulting in endothelial cell impairment, potentially leading to multiple organ failure. Vitronectin (VN) is a 75-kDa glycoprotein (VN₇₅) cleaved into two forms (VN₇₅ or VN_65/10) by furin, which is regulated by intracellular PAI-1. VN protects against radiation-induced endothelial cell death, but the mechanisms involved in VN processing and its interactions with intra- and extracellular PAI-1 remain unclear. We examined these processes in cells in vitro using recombinant proteins or overexpression of VN and PAI-1 genes, including furin-susceptible (T³⁸¹) and furin-resistant VN (A³⁸¹). VN processing was analyzed using a mutant PAI-1 with relatively weaker binding to VN. VN function was evaluated by survival of radiation-damaged endothelial cells. Wild-type, but not mutant PAI-1 inhibited furin-dependent VN processing. Gene transfer revealed that furin-susceptible VN was processed more than the furin-resistant form, but processing of both was inhibited by PAI-1 overexpression. Intracellular PAI-1 formed a complex with VN₇₅ (T³⁸¹) in cells and media, and the VN₇₅ form was secreted preferentially. Only VN₇₅ protected against radiation-induced endothelial cell death, in which its effect was abolished by wild-type but not mutant PAI-1. These findings indicate that intracellular PAI-1 inhibits VN processing and protects against radiation-induced endothelial cell death.

Infusion of endothelial progenitor cells ameliorates liver injury in mice after haematopoietic stem cell transplantation

BACKGROUND & AIMS

Injury to liver sinusoidal endothelial cells (LSECs) is thought to be the initial factor for Hepatic veno-occlusive disease, a severe complication after haematopoietic stem cell transplantation (HSCT). Endothelial progenitor cells (EPCs) have the capacity to differentiate into endothelial cells and play a critical role in vasculogenesis, tissue regeneration and repair. Whether EPCs infusion ameliorates LSECs injury remains unclear. The aim of this study was to evaluate the effects of EPCs on liver injury in mice after HSCT.

METHODS

Mice received HSCT without or with EPCs infusion (HSCT + EPCs). Untreated mice were used as control. Liver and whole blood were collected post HSCT and used for the analysis of pathology of liver sinusoidal endothelial cells (LSECs) and hepatocytes, liver ultrastructure, function, level of IL-6, TNF-α and platelet activation.

RESULTS

Severe LSECs injury, hepatocyte damage, abnormal liver function was observed in HSCT group. In addition, increased P-selectin expression and secretion of IL-6, TNF-α was also found. However, all the above changes were alleviated in HSCT + EPCs at all the time points and normalized at the endpoint. Meanwhile, EPCs-induced repair of LSECs and hepatocytes was totally inhibited by the addition of anti-VE-cadherin antibody.

CONCLUSIONS

EPCs infusion ameliorated the damage to LSECs and hepatocytes as well as reduced secretion of IL-6, TNF-α and inhibited platelet activation after HSCT, leading to improved liver function, suggesting EPCs might be a new therapeutic strategy in the prophylaxis of liver injury after HSCT.

Role of Pharmacogenetics in Hematopoietic Stem Cell Transplantation Outcome in Children

Hematopoietic stem cell transplantation (HSCT) is an established therapeutic procedure for several congenital and acquired disorders, both malignant and nonmalignant. Despite the great improvements in HSCT clinical practices over the last few decades, complications, such as graft vs. host disease (GVHD) and sinusoidal obstructive syndrome (SOS), are still largely unpredictable and remain the major causes of morbidity and mortality. Both donor and patient genetic background might influence the success of bone marrow transplantation and could at least partially explain the inter-individual variability in HSCT outcome. This review summarizes some of the recent studies on candidate gene polymorphisms in HSCT, with particular reference to pediatric cohorts. The interest is especially focused on pharmacogenetic variants affecting myeloablative and immunosuppressive drugs, although genetic traits involved in SOS susceptibility and transplant-related mortality are also reviewed.