Avoiding hepatic veno-occlusive disease: what do we know and where are we going?

Targeted-dose of busulfan: Higher risk of sinusoidal obstructive syndrome observed with systemic exposure dose above 5000 µMol⸱min. A historically controlled clinical trial

Busulfan is given in the conditioning regimens preceding hematopoietic stem cell transplantation (HSCT), and plasma levels can be monitored. A targeted, individualized systemic exposure (SE) dose can be achieved by calculating the area under the plasma concentration versus time curve (AUC). The objective of this study was to determine a cutoff value for safety for the AUC for busulfan plasma levels in patients undergoing HSCT. A total of 149 consecutive HSCT patients were studied. After an oral test dose of busulfan, we set target doses of 4000, 5000, or 6000 µMol⸱min/day, and analyzed the AUC of oral or intravenous Bu. These patients were compared with 53 historical control subjects who had received myeloablative conditioning regimen without busulfan pharmacokinetic monitoring. Using a test dose and the administration route had no impact on the sinusoidal obstructive syndrome (SOS) incidence, transplant-related mortality or 1-year overall survival. However, patients receiving busulfan at doses set up at AUC > 5000 had an increased risk to develop SOS after HSCT (hazard ratio 3.39, p = 0.034, 95% CI 1.09-10.52). Adjusting the busulfan dose according to SE levels target dose during conditioning is associated with lower rates of oral severe mucositis and SOS. A cutoff of 5000 µMol⸱min is safe and does not impair survival.

Health impact of hepatic-venous-occlusive disease in a small town in Ethiopia-Case study from Tahtay koraro district in Tigray region, 2017

Background

Hepatic venous-occlusive disease is blockage of microscopic veins in the liver causing 20–50% mortality. Ingestion of pyrrolizidine alkaloid plant, radiation therapy, and post-bone-marrow-transplant reactions are the commonest causes. In Ethiopia, a venous-occlusive disease outbreak was identified in 2002 in Tahtay Koraro district, Tigray. Suspected due to ingestion of the toxic pyrrolizidine alkaloid plant Ageratum conyzoids, found throughout the district. We aimed to describe the surveillance data of venous-occlusive disease from September 2006 to August 2016 in Tahtay koraro district, Ethiopia, 2017.

Methodology

We defined a possible Hepatic venous-occlusive disease case as any patient with abdominal pain for at least 2 weeks, abdominal distention, and hepato-splenomegaly during September 2006-August 2016. We reviewed previous district line lists, weekly reports, and clinical records to identify and describe cases. Agricultural interventions were obtained from the agricultural offices of the district.

Result

We identified 179 possible cases with 83 deaths with a case-fatality rate of 46.3%. Among cases, 110 (61.5%) were males and 113 (63%) were >15 years. In total, 164 (91.6%) cases were from one village (Kelakil). The pick number of cases of VOD in this village was during 2008/09 which was 1076. The highest incidence (86/100,000) occurred in 2008. During the study period, 2,746 years of potential life were lost due to Hepatic venous-occlusive disease. Mechanical removal of the Ageratum started in 2011.

Conclusion

Hepatic venous-occlusive disease was an ongoing problem in Tahtay Koraro; However, the problem has largely been alleviated by displacing people from the affected area and removing the causative weed. More research is needed to understand why Kelakil village was more affected despite the widespread presence of the weed. Chemical and mechanical removal of the Ageratum could strengthen intervention activities.

Evaluation of the therapeutic effects of rice husk nanosilica combined with platelet-derived growth factor in hepatic veno-occlusive disease

Veno-occlusive disease is an important pattern of hepatotoxicity associated with antineoplastic drugs. The study investigated the possible therapeutic effects of RHS nanoparticles combined with a PDGF on veno-occlusive disease (VOD) in liver elicited in rats with DAC. In this work, nanosilica (SiO₂) was successfully prepared from rice husk, and its physicochemical characteristics were investigated using EDX, XRD, N₂ adsorption-desorption isotherm, SEM, and TEM. Forty-eight male Sprague-Dawely rats were distributed into 6 groups, with 8 rats in each. The first group served as the control. In the second group, animals were infused with DAC (0.015 mg/kg; 1-3 days) by intraperitoneal injection (i.p.). In the third group, rats were injected i.p. with DAC, and then at 24 h following the last dose of DAC, received nano-RHS incorporated with PDGF twice a week for 4 weeks. In the fourth group, normal animals were injected with RHS. In the fifth group, normal rats received PDGF, and in the sixth group, normal rats received nano-RHS combined with PDGF. The prepared nanosilica showed type II adsorption isotherm characteristic for mesoporous materials with a specific surface area of 236 m²/g. TEM imaging confirmed the production of nanoparticles via the followed preparation procedure. Radical scavenging potential for nano-RHS was determined using two different in-vitro assays: DPPH, and ABTS radicals. The results of this work show that administration of nano-RHS combined with PDGF significantly reversed the oxidative stress effects of DAC as evidenced by a decrease in liver function. It can be concluded that the nano-RHS combined with PDGF is useful in preventing oxidative stress and hepatic VOD induced by chemotherapy such as DAC.

The Role of Thromboelastography in Pediatric Patients with Sinusoidal Obstructive Syndrome Receiving Defibrotide

Sinusoidal obstructive syndrome (SOS) is a potentially fatal form of hepatic injury after hematopoietic stem cell transplantation. Patients can develop liver dysfunction, portal hypertension, ascites, coagulopathies, and multisystem organ failure. The mortality rate of severe SOS has been reported as high as 98% by day 100 after transplantation. Defibrotide, which is now approved for the treatment of SOS, has significantly decreased mortality. Defibrotide is a polynucleotide with profibrinolytic, anti-ischemic, and anti-inflammatory activity. These properties can increase the risk of life-threatening bleeding in this patient population. Previous protocols have suggested maintaining international normalized ratio ≤ 1.5, platelets > 30 k/uL, and fibrinogen ≥ 150 mg/dL to minimize this risk of bleeding. However, this can be challenging in fluid-sensitive patients with SOS. Thromboelastography (TEG) is a functional assay that evaluates the balance of procoagulant and anticoagulant proteins. In this series, TEG was used to guide defibrotide therapy as well as blood product transfusions in SOS patients with abnormal coagulation studies. Each patient recovered from SOS and had no bleeding complications. A randomized clinical trial is the next step in supporting the use of TEG in SOS patients with abnormal coagulation studies receiving defibrotide therapy.

Cytokine serum levels during post-transplant adverse events in 61 pediatric patients after hematopoietic stem cell transplantation

Background

Veno-occlusive disease, Graft-versus-Host disease, invasive or localized bacterial, viral and fungal infections are known as adverse events after hematopoietic stem cell transplantation representing the major cause for morbidity and mortality. Detection and differentiation of these adverse events are based on clinical symptoms and routine measurements of laboratory parameters.

Methods

To identify the role of cytokines as a possible complication-marker for adverse events, 61 consecutive pediatric patients with a median age of 7.0 years who underwent hematopoietic stem cell transplantation were enrolled in this single-center retrospective study. Interleukin-1 beta (IL-1β), soluble interleukin-2 receptor (sIL-2R), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10) and tumor necrosis factor-α serum (TNF-α) levels were regularly assessed after transplantation and during transplantation related adverse events.

Results

Veno-occlusive disease was accompanied by a significant increase in levels of IL-6, IL-8 and TNF-α.Graft-versus-Host disease was associated with a significant increase of IL-10, sIL-2R, IL-6 and TNF-α, depending on the respective stage or grade. Cytokine IL-6 enabled a significant differentiation between sepsis and fungemia, sepsis and viremia, and sepsis and bacteremia. Moreover, cytokine IL-8 enabled a significant differentiation between sepsis and viremia, sepsis and bacteremia, and bacteremia and viremia whereas IL-10 made a distinction between sepsis and viremia possible.

Conclusion

The data demonstrate that proinflammatory cytokines might be putative indicators for early detection and differentiation of post-transplant adverse events and may allow prompt and adequate clinical intervention. Prospective clinical trials are needed to evaluate these findings.

Sinusoidal obstruction syndrome (hepatic veno-occlusive disease)

Hepatic sinusoidal obstruction syndrome (SOS) is an obliterative venulitis of the terminal hepatic venules, which in its more severe forms imparts a high risk of mortality. SOS, also known as veno-occlusive disease (VOD), occurs as a result of cytoreductive therapy prior to hematopoietic stem cell transplantation (HSCT), following oxaliplatin-containing adjuvant or neoadjuvant chemotherapy for colorectal carcinoma metastatic to the liver and treated by partial hepatectomy, in patients taking pyrrolizidine alkaloid-containing herbal remedies, and in other particular settings such as the autosomal recessive condition of veno-occlusive disease with immunodeficiency (VODI). A central pathogenic event is toxic destruction of hepatic sinusoidal endothelial cells (SEC), with sloughing and downstream occlusion of terminal hepatic venules. Contributing factors are SEC glutathione depletion, nitric oxide depletion, increased intrahepatic expression of matrix metalloproteinases and vascular endothelial growth factor (VEGF), and activation of clotting factors. The clinical presentation of SOS includes jaundice, development of right upper-quadrant pain and tender hepatomegaly, ascites, and unexplained weight gain. Owing to the potentially critical condition of these patients, transjugular biopsy may be the preferred route for liver biopsy to exclude other potential causes of liver dysfunction and to establish a diagnosis of SOS. Treatment includes rigorous fluid management so as to avoid excessive fluid overload while avoiding too rapid diuresis or pericentesis, potential use of pharmaceutics such as defibrotide, coagulolytic agents, or methylprednisolone, and liver transplantation. Proposed strategies for prevention and prophylaxis include reduced-intensity conditioning radiation for HSCT, treatment with ursodeoxycholic acid, and inclusion of bevacizumab with oxaliplatin-based chemotherapeutic regimes. While significant progress has been made in understanding the pathogenesis of SOS and in mitigating against its adverse outcomes, this condition remains a serious complication of a selective group of medical treatments.

Human leukocyte antigen DR surface expression on CD14+ monocytes during adverse events after hematopoietic stem cell transplantation

The human leukocyte antigen DR surface expression on CD14+ monocytes reflects the degree to which these cells have been activated. Given the central role monocytes and macrophages play in the immune system, a decreased human leukocyte antigen DR expression on CD14+ monocytes results in a hallmark of altered immune status during systemic inflammatory response syndrome. We hypothesize that human leukocyte antigen DR expression might be similarly altered after hematopoietic stem cell transplantation and during post-transplant complications. Using flow cytometry, this study investigates the human leukocyte antigen DR surface expression of CD14+ monocytes in 30 pediatric and young adult patients up to 1 year after hematopoietic stem cell transplantation. Normal values were derived from a control group of healthy children, adolescents, and young adults. Human leukocyte antigen DR expression decreased significantly prior and during bacterial infection or sepsis. By contrast, human leukocyte antigen DR expression levels were elevated before and at the time of viremia. Human leukocyte antigen DR expression was also elevated during acute graft-versus-host disease. In contrast, the expression was reduced when patients had hepatic veno-occlusive disease. A significant decrease of human leukocyte antigen DR expression was associated with a relapse of the underlying disease and before death. Human leukocyte antigen DR expression on CD14+ monocytes appears to be a promising parameter that might allow identification of patients at risk after hematopoietic stem cell transplantation.

[Implication of hyaluronic acid in normal and pathological angiogenesis. Application for cellular engineering]

Angiogenesis is a physiological process that allows the formation of new blood vessels, either from the local vascular structures, or from circulating endothelial progenitor cells, mobilized from the bone marrow, and attracted to the neovascularization site. This mechanism is controlled by pro-angiogenic molecules. It is crucial to supply oxygen and nutrients to tissues during growth, embryonic development or tissue regeneration in response to injuries. Thus, the dermis part of the skin is highly vascularized by a dense network of small and medium arteries and of capillaries and venules. In case of injury, rapid tissue repair is possible through this vascular network. However, once the vascularization is restored in tissue repair, the process of angiogenesis is negatively regulated by anti-angiogenic molecules. Controling the balance between pro-and anti-angiogenic agents is crucial and its deregulation leads to serious disease. The extracellular matrix plays an important role in controlling angiogenesis, allowing at least, the distribution of growth factors and the regulation of endothelial cell migration. Among these matrix components, hyaluronic acid plays a major role in the mechanical properties of connective tissues in ensuring their hydration. This glycosaminoglycan is a large size polymer, whose breakdown products strongly act on angiogenesis, especially in pathological situations (cancer, inflammation). Regarding its biological and mechanical properties, hyaluronic acid is used as matrix in tissue engineering, for improving the revascularization of tissues like skin.

Hepatic veno-occlusive disease following stem cell transplantation: incidence, clinical course, and outcome

The occurrence of hepatic veno-occlusive disease (VOD) has been reported in up to 60% of patients following stem cell transplantation (SCT), with incidence varying widely between studies depending on the type of transplant, conditioning regimen, and criteria used to make the diagnosis. Severe VOD is characterized by high mortality and progression to multiorgan failure (MOF); however, there is no consensus on how to evaluate severity. This review and analysis of published reports attempts to clarify these issues by calculating the overall mean incidence of VOD and mortality from severe VOD, examining the effect of changes in SCT practice on the incidence of VOD over time, and discussing the methods used to evaluate severity. Across 135 studies performed between 1979 and October 2007, the overall mean incidence of VOD was 13.7% (95% confidence interval [CI]=13.3%-14.1%). The mean incidence of VOD was significantly lower between 1979-1994 than between 1994-2007 (11.5% [95% CI, 10.9%-12.1%] vs 14.6% [95% CI, 14.0%-15.2%]; P <.05). The mortality rate from severe VOD was 84.3% (95% CI, 79.6%-88.9%); most of these patients had MOF, which also was the most frequent cause of death. Thus, VOD is less common than early reports suggested, but the current incidence appears to be relatively stable despite recent advances in SCT, including the advent of reduced-intensity conditioning. The evolution of MOF in the setting of VOD after SCT can be considered a reliable indication of severity and a predictor of poor outcome.

Pulmonary veno-occlusive disease following hematopoietic stem cell transplantation: a rare model of endothelial dysfunction

Veno-occlusive disease is among the most serious complications following hematopoietic stem cell transplantation. While hepatic veno-occlusive disease occurs more commonly, the pulmonary variant remains quite rare and often goes unrecognized antemortem. Endothelial damage may represent the pathophysiologic foundation of these clinical syndromes. Recent advances in the treatment of hepatic veno-occlusive disease may have application to its pulmonary counterpart.

Renal disease in patients with cancer

Kidney disease is very common in patients with cancer. Nephrologists are vital members of the multidisciplinary care team for these patients. Given the high prevalence of comorbidities in patients treated for active malignancy, it is not surprising that these individuals frequently develop renal diseases that are common among other hospitalized patients, such as those arising from sepsis, hypotension or use of nephrotoxic agents (e.g. radiocontrast or antimicrobial agents). The role of the nephrologist in these cases differs little with respect to the presence or absence of cancer. On the other hand, there are several renal syndromes that are unique to patients with cancer, being caused either by the cancer itself or by its treatment. These syndromes are reviewed here. In addition, patients who are receiving chemotherapy often require dialysis for either acute or chronic kidney disease. Unfortunately, there is very little information on the clearance characteristics of most chemotherapeutic agents. In cancer patients with renal disease, both the timing of administration and the dose-adjustment of chemotherapy must rely on clinical experience and close clinical observation.

Successful treatment of hepatic veno-occlusive disease after myeloablative allogeneic hematopoietic stem cell transplantation by early administration of a short course of methylprednisolone

Hepatic veno-occlusive disease (VOD) is one of the most common and important regimen-related toxicities observed after hematopoietic stem cell transplantation (HSCT). There are no universally accepted preventative or therapeutic approaches for VOD. We prospectively evaluated the safety and efficacy of a short course of methylprednisolone (MP) in 48 patients undergoing allogeneic HSCT who were diagnosed with hepatic VOD. MP was administered at a dose of 0.5 mg/kg i.v. every 12 h for a total of 14 doses, and then discontinued without taper. Thirty (63%) patients responded with a reduction in total serum bilirubin of 50% or more after 10 days of treatment. In univariate analysis, non-responders had a higher total bilirubin at the start of MP therapy, more weight gain, evidence of fungal infection and platelet refractoriness. High SGPT and early engraftment were significant factors among responders. Twenty-five of the 30 responders survived up to day +100, whereas all but three non-responders died within 100 days post-HSCT, for a probability of survival of 58% among responders and 10% for non-responders. Prospective comparative studies are needed to confirm the observed encouraging outcome of MP therapy for VOD.

Pretransplant Conditioning in Adults and Children: Dose Assurance With Intravenous Busulfan

PURPOSE/OBJECTIVES

To provide clinical insights into dosing and administration of IV busulfan, a conditioning agent for hematopoietic stem cell transplantation (HSCT).

DATA SOURCES

Review of published literature related to busulfan pretransplant conditioning using MEDLINE. Meeting abstracts, investigational protocols, and pharmaceutical manufacturers' package inserts also were reviewed.

DATA SYNTHESIS

Busulfan is an effective myeloablative conditioning agent for HSCT. The IV formulation increases dose assurance and the ability to target a therapeutic window. Therapeutic drug monitoring ensures that targeted blood levels are achieved, especially in children, thereby preventing underdosing, which can lead to disease progression or rejection, as well as overdosing, which can cause an increased risk of toxic side effects.

CONCLUSIONS

IV busulfan is a convenient, safe, and effective conditioning agent used in HSCT that has a predictable pharmacokinetic profile.

IMPLICATIONS FOR NURSING

An understanding of the pharmacokinetic principles underlying the relationship between the therapeutic window for busulfan and optimal HSCT outcomes will facilitate proper dosing and administration of IV busulfan.

Review article: updates in the pathogenesis and therapy of hepatic sinusoidal obstruction syndrome

Hepatic sinusoidal obstruction syndrome is frequently linked to high-dose chemotherapy/total-body irradiation in recipients of haematopoietic stem cell transplantation, long-term use of azathioprine after organ transplantation and other chemotherapeutic agents. The incidence of hepatic sinusoidal obstruction syndrome varies from 0% to 70%, and is decreasing. Disease risk is higher in patients with malignancies, hepatitis C virus infection, those who present late, when norethisterone is used to prevent menstruation, and when broad-spectrum antibiotics and antifungals are used during and after the conditioning therapy. Hepatic sinusoidal obstruction syndrome presents with tender hepatomegaly, hyperbilirubinaemia and ascites, and diagnosis is mainly clinical (Seattle and Baltimore Criteria). Imaging excludes biliary obstruction and malignancy, but cannot establish accurate diagnosis. Hepatic sinusoidal obstruction syndrome may be prevented by avoiding the highest risk regimens, using non-myelo-ablative regimens, and reducing total-body irradiation dose. Treatment is largely symptomatic and supportive, because 70-80% of patients recover spontaneously. Tissue plasminogen activator plus heparin improves outcome in <30% of cases. Defibrotide, a polydeoxyribonucleotide, is showing encouraging results. Transjugular intrahepatic porto-systemic shunt relieves ascites, but does not improve outcome. Liver transplantation may be an option in the absence of malignancy. Prognosis is variable and depends on disease severity, aetiology and associated conditions. Death is most commonly caused by renal or cardiopulmonary failure.

Usefulness of Sequential Automated Analysis of Fragmented Red Blood Cells for the Differential Diagnosis of Thrombotic Thrombocytopenic Purpura-Hemolytic Uremic Syndrome following Allogeneic Hematopoietic Cell Transplantation

Differentiating thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) from other complications following allogeneic hematopoietic cell transplantation (HPCT) requires objective, reliable markers. To this purpose, we assessed the clinical usefulness of sequential quantified analysis of fragmented red blood cells (FRC) with the Sysmex XE-2100 automated hematology analyzer. The correlation between manual and automated counting was significant (r = 0.917; P < .0001). Of 25 cases, the peak FRC percentage (FRC%) exceeded 1.3% after allogeneic HPCT in 11 cases, and lactate dehydrogenase levels were elevated in 5 of these 11 cases. Two patients received diagnoses of TTP-HUS following allogeneic HPCT, and both had initial diagnoses of acute graft-versus-host disease. In both cases, the sharp increase in the FRC% to >3% simultaneously with clinical exacerbation was helpful for differentiating TTP-HUS following allogeneic HPCT from other complications. We conclude that FRC% data sequentially obtained by an automated count seem to be useful as an objective marker of TTP-HUS following allogeneic HPCT.

Four-year survival after trans-jugular intrahepatic porto-systemic shunt for veno-occlusive disease following autologous bone marrow transplantation

Severe hepatic veno-occlusive disease is still a potentially lethal complication after bone marrow transplantation. We here report the case of a patient who developed liver veno-occlusive disease with severe hemodynamic dysfunction and was successfully treated by means of a trans-jugular intrahepatic portosystemic shunt. After three years, he is still disease-free with a functioning shunt and a normal laboratory liver profile. A trans-jugular intrahepatic portosystemic shunt is a treatment option that has been used in very few patients affected by hepatic veno-occlusive disease; its indications and timing remain to be established.

Age is a risk factor for chemotherapy-induced hepatopathy with vincristine, dactinomycin, and cyclophosphamide

PURPOSE

To evaluate the spectrum of and determine the risk factors for the development of liver toxicity (hepatopathy) after therapy with vincristine, dactinomycin, and cyclophosphamide (VAC) for rhabdomyosarcoma in children and adolescents.

PATIENTS AND METHODS

We prospectively captured all events of hepatopathy occurring on the ongoing Children's Oncology Group intermediate risk protocol, D9803, for children with rhabdomyosarcoma. Patients enrolled onto this trial were randomly assigned to receive either VAC alone or VAC alternating with vincristine, topotecan, and cyclophosphamide. In addition, we reviewed the toxicity database and requested additional information for all patients with elevated bilirubin or transaminase levels. Risk factors were analyzed.

RESULTS

Of 339 patients enrolled through August 2002, 18 developed hepatopathy. All events were captured by mandated toxicity reporting and filing of MedWatch forms, with no additional cases found after the additional search of the database. Four children died after developing this toxicity. All cases occurred after cycles of VAC (n = 16) or vincristine and cyclophosphamide with concomitant abdominal radiotherapy (n = 2). The onset of hepatopathy was 5 to 16 days from the start of a treatment cycle. For the 89 patients under 36 months of age, the risk of hepatopathy was 15%, with two deaths. For the 239 children 3 years of age or older, the risk for hepatopathy was 4%, with two deaths.

CONCLUSION

The greatest risk factor for development of hepatopathy after VAC therapy was age. Dose modifications for younger children receiving VAC therapy are recommended.

Glutathione S-transferase M1 polymorphism: a risk factor for hepatic venoocclusive disease in bone marrow transplantation

Hepatic venoocclusive disease (HVOD) in bone marrow transplantation (BMT) is attributed to toxicity of cytoreductive agents, especially busulfan and cyclophosphamide, in the conditioning therapy. Busulfan, as well as the metabolites of cyclophosphamide, are conjugated with glutathione (GSH), catalyzed by enzymes of the glutathione S-transferase (GST) family. To assess the impact of polymorphisms of the GST genes, GSTM1 and GSTT1, on the risk of HVOD, we evaluated 114 consecutive patients with beta-thalassemia major undergoing BMT. There was a significantly increased incidence of HVOD in patients with the GSTM1-null genotype compared with those with the GSTM1-positive genotype (46.5% vs 18.3%; P =.001). Pharmacokinetic analysis in these patients showed that the clearance of busulfan was higher and first-dose steady-state concentration was lower among those with HVOD (0.403 +/- 0.06 vs 0.33 +/- 0.071 L/h/kg, Student t test P value =.000 01; and 508 +/- 125 vs 656 +/- 255 ng/mL, t test P value =.001, respectively). We conclude that the GSTM1-null genotype predisposes to HVOD, and the sinusoidal endothelial cells and hepatocyte damage may be mediated by metabolites of busulfan through depletion of the cellular GSH pool.

In children and adolescents, the pharmacodynamics of high-dose busulfan is dependent on the second alkylating agent used in the combined regimen (melphalan or thiotepa)

A strong relationship has been demonstrated between high systemic exposure to busulfan and the occurrence of hepatic veno-occlusive disease (HVOD) after a busulfan-cyclophosphamide regimen (BU CY). We report a prospective study aimed at exploring the pharmacodynamics of high-dose busulfan combined with either melphalan (BU MEL) or thiotepa (BU TTP) followed by autologous stem cell transplantation in children and adolescents with a malignant solid tumor. Busulfan was given orally at a total dose of 600 mg m(-2). In all, 45 patients with a median age of 6.3 years were included in the study: 25 received BU MEL and 20 received BU TTP. The incidence of HVOD was 44% (CI 95% [23-65%]) in the BU MEL group and 25% (CI95% [9-49%]) in the BU TTP group. In the BU TTP group, patients who developed HVOD had a significantly higher AUC 0-6 h after the 13th dose (6201+/-607 h ng ml(-1)) than those who did not (5024+/-978 h ng ml(-1)) (P<0.05). In the BU MEL group, there was no difference in terms of systemic exposure to busulfan between patients who developed HVOD and those who did not. In conclusion, the guidelines established for monitoring BU CY cannot be extrapolated when busulfan is combined with another drug.

Veno-occlusive disease: cytokines, genetics, and haemostasis

Hepatic veno-occlusive disease (VOD) is a major cause of morbidity and mortality following high dose cytotoxic therapy for stem cell transplantation (SCT). Pre-existing liver damage, SCT-related therapy, and genetic polymorphisms all appear to increase the risk of developing VOD. Studies of biological markers during SCT suggest that cytokines, haemostasis, and hepatic drug metabolism via the glutathione pathway are all involved in the pathogenesis of VOD. Until recently, treatment options were limited and experimental therapies directed at the pathogenesis of the disease were mostly unsuccessful. However, Defibrotide, a relatively new agent that has modulatory effects on vascular endothelium, cytokine release, and haemostasis, has been used with some success in the management and prophylaxis of VOD. In the future, a better understanding of genetic polymorphisms and biological markers which may be important in the pathogenesis of VOD, may enable us to predict which patients are most likely to be affected.

Veno-occlusive Disease

Therapy for veno-occlusive disease of the liver (VOD) occurring after bone marrow transplantation should be directed at those with moderate or severe disease who will not recover on their own. Thrombolytic therapy may have a role in severe VOD as long as there is no renal or lung impairment. However, the risk of bleeding complications, including the risk of cerebral hemorrhage, must be considered in these patients. Defibrotide has shown promise for treatment of severe VOD but is not yet widely available in the United States. Therapy directed at reducing portal hypertension such as transjugular intrahepatic portosystemic shunts helps reduce ascites but has no effect on mortality. Liver transplantation has been reported but should be considered only in patients with severe liver failure who would have a good outcome in the absence of liver disease or have undergone bone marrow transplantation for benign disease. The most important advances in VOD has been in the prevention of this syndrome by recognizing the risk factors for it and changes in conditioning regimens before bone marrow transplantation.