Individualized dosing guidelines for PEGasparaginase and factors influencing the clearance: a population pharmacokinetic model

Considerable inter- and intra-patient variability exist in serum activity levels of PEGasparaginase, essential for pediatric acute lymphoblastic leukemia (ALL) treatment. A population pharmacokinetic (popPK) model was developed, identifying patient characteristics that explain these variabilities. Patients (n=92) were treated according to the Dutch Childhood Oncology Group (DCOG) ALL-11 protocol, using therapeutic drug monitoring to individualize PEGasparaginase doses. Non-linear mixed effects modeling (NONMEM) was used to analyze popPK evaluating several covariates. The final model was validated using an independent database (n=28). Guidelines for starting doses and dose adjustments were developed. A one-compartment model with timedependent clearance was adequately described in popPK. Normalization of clearance and volume of distribution by body surface area reduced inter-individual variability. Clearance was 0.084 L/day/m² for 12.7 days, increasing by 0.082 L/day/m²/day thereafter. Clearance was 38% higher during an infection, and 11-19% higher during induction treatment than during intensification and maintenance (P<0.001). In order to target an asparaginase activity level of 100 IU/L, a loading dose of 800 IU/m² (induction) and 600 IU/m² (intensification) is advised. In conclusion, variability of PEGasparaginase activity levels can be explained by body surface area, the treatment phase and the occurrence of an infection. With this popPK model, PEGasparaginase treatment can be individualized further, taking into account the covariates and the dosing guidelines provided. (clinicaltrials gov. Identifier [CCMO register]: NL50250.078.14).     

Pre-existing antibodies against polyethylene glycol reduce asparaginase activities on first administration of pegylated E. coli asparaginase in children with acute lymphocytic leukemia

Antibodies against polyethylene glycol (PEG) in healthy subjects raise concerns about the efficacy of pegylated drugs. We evaluated the prevalence of antibodies against PEG among patients with acute lymphoblastic leukemia (ALL) prior to and/or immediately after their first dose of pegylated E.coli asparaginase (PEG-ASNase). Serum samples from 701 children (673 with primary ALL, 28 with relapsed ALL) and 188 adults with primary ALL were analyzed for anti-PEG IgG and IgM. Measurements in 58 healthy infants served as a reference to define cut-points for antibody-positive and -negative samples. The prevalence of anti-PEG antibodies in ALL patients prior to the first administration of PEG-ASNase was 13.9% for anti-PEG IgG and 29.1% for anti-PEG IgM. After administration of PEG-ASNase the prevalence of anti-PEG antibodies decreased to 4.2% for anti-PEG IgG and to 4.5% for anti-PEG IgM. Pre-existing anti-PEG antibodies did not inhibit PEGASNase activity but significantly reduced PEG-ASNase activity levels in a concentration-dependent manner. Although pre-existing anti-PEG antibodies were not boosted, pre-existing anti-PEG IgG were significantly associated with first-exposure hypersensitivity reactions (Common Terminology Criteria for Adverse Events grade 2) (P<0.01; Fisher exact test). Two of four patients with pre-existing anti-PEG IgG and first-exposure hypersensitivity reactions were not switched to Erwinia ASNase and continued on PEG-ASNase with sufficient activity (≥100 U/L). In conclusion, pre-existing anti-PEG antibodies were detected in a considerable proportion of patients with ALL and although they did not inhibit PEG-ASNase activity, they were associated with lower serum PEG-ASNase activity levels. Patients with pre-existing antibodies may show mild to moderate signs of hypersensitivity reaction after their first administration PEG-ASNase, which may be successfully addressed by re-challenge.     

Acute lymphoblastic leukaemia patients treated with PEGasparaginase develop antibodies to PEG and the succinate linker

Polyethylene glycol (PEG) conjugated asparaginase (PEGasparaginase) is essential for treatment of paediatric acute lymphoblastic leukaemia. We developed an assay identifying antibodies against the PEG-moiety, the linker and the drug itself in patients experiencing hypersensitivity reactions to PEGasparaginase. Eighteen patients treated according to the DCOG ALL-11 protocol, with a neutralizing hypersensitivity reaction to PEGasparaginase to the first PEGasparaginase doses in induction (12 patients) or during intensification after interruption of several months (6 patients) were included. ELISA was used to measure antibodies, coating with the succinimidyl succinate linker conjugated to BSA, PEGfilgrastim and Escherichia coli asparaginase, and using hydrolysed PEGasparaginase and mPEG_5,000 for competition. Anti-PEG antibodies were detected in all patients (IgG 100%; IgM 67%) of whom 39% had anti-PEG antibodies exclusively. Pre-existing anti-PEG antibodies were also detected in patients who not previously received a PEGylated therapeutic (58% IgG; 21% IgM). Antibodies against the SS-linker were predominantly detected during induction (50% IgG; 42% IgM). Anti-asparaginase antibodies were detected in only 11% during induction but 94% during intensification. In conclusion, anti-PEG and anti-SS-linker antibodies predominantly play a role in the immunogenic response to PEGasparaginase during induction. Thus, switching to native E. coli asparaginase would be an option for adequate asparaginase treatment.     

Effects of Erwinia-asparaginase on the coagulation system

Abstract: l -Asparaginase treatment during induction therapy in acute lymphoblastic leukaemia (ALL) is known to be frequently complicated by thromboembolic events. It was recently suggested that l -asparaginase derived from Erwinia chrysanthemi alters the coagulation system less severely than does Escherichia coli asparaginase. In a series of 11 adult patients with ALL, we investigated some parameters of the coagulation system during treatment with Erwinia asparaginase. The doses employed were rather high; all patients below the age of 60 years received 15000 U/m² daily over 14 days. In accordance with what is known from treatment with E. coli asparaginase, we observed significant lowering of antithrombin as well as of fibrinogen. However, as to fibrinogen indeed a significant decrease had occurred prior to the institution of Erwinia asparaginase treatment. The most striking observation in the present study was that the levels of prothrombin complex, reflecting the function of K-vitamin dependent coagulation factors II, VII and X, remained within normal ranges during treatment. This indicates that these coagulation factors were not affected by Erwinia asparaginase, an observation at variance with several reports where E. coli asparaginase was investigated. This latter observation was the only finding which could lend support to the view that Erwinia asparaginase affects the coagulation system less than E. coli asparaginase. Finally, one of our patients developed a sinus thrombosis, a severe thrombotic complication.     

Cerebrospinal fluid asparagine depletion during pegylated asparaginase therapy in children with acute lymphoblastic leukaemia

L‐asparaginase is an important drug in the treatment of childhood acute lymphoblastic leukaemia (ALL). Cerebrospinal fluid (CSF) asparagine depletion is considered a marker of asparaginase effect in the central nervous system (CNS) and may play a role in CNS‐directed anti‐leukaemia therapy. The objective of this study was to describe CSF asparagine depletion during 30 weeks of pegylated asparaginase therapy, 1000 iu/m² i.m. every second week, and to correlate CSF asparagine concentration with serum L‐asparaginase enzyme activity. Danish children (1–17 years) with ALL, treated according to the Nordic Society of Paediatric Haematology and Oncology ALL2008 protocol, standard and intermediate risk, were included. CSF samples were obtained throughout L‐asparaginase treatment at every scheduled lumbar puncture. A total of 128 samples from 31 patients were available for analysis. Median CSF asparagine concentration decreased from a pre‐treatment level of 5·3 μmol/l to median levels ≤1·5 μmol/l. However, only 4/31 patients (five samples) had CSF asparagine concentrations below the limit of detection (0·1 μmol/l). In 11 patients, 24 paired same day serum and CSF samples were obtained. A decrease in CSF asparagine corresponded to serum enzyme activities above 50 iu/l. Higher serum enzyme activities were not followed by more extensive depletion. In conclusion, pegylated asparaginase 1000 iu/m² i.m. every second week effectively reduced CSF asparagine levels.     

Prospective,real-time monitoring of pegylated Escherichia coli and Erwinia asparaginase therapy in childhood acute lymphoblastic leukaemia and non-Hodgkin lymphoma in Belgium

Asparaginase (ASNase) is an important anti-leukaemic drug in the treatment of childhood acute lymphoblastic leukaemia (ALL) and non-Hodgkin lymphoma (NHL). A substantial proportion of patients develop hypersensitivity reactions with anti-ASNase neutralising antibodies, resulting in allergic reactions or silent inactivation (SI), and characterised by inactivation and rapid clearance of ASNase. We report results of a prospective, real-time therapeutic drug monitoring of pegylated Escherichia coli (PEG-)ASNase and Erwinia ASNase in children treated for ALL and NHL in Belgium. Erwinia ASNase was given as second-line after hypersensitivity to PEG-ASNase. In total, 286 children were enrolled in the PEG-ASNase cohort. Allergy was seen in 11·2% and SI in 5·2% of patients. Of the 42 patients treated with Erwinia ASNase, 7·1% experienced allergy and 2·4% SI. The median trough PEG-ASNase activity was high in all patients without hypersensitivity. After Erwinia administration significantly more day 3 samples had activities <100 IU/l (62·5% vs. 10% at day 2 (D2)). The median D2 activity was significantly higher for intramuscular (IM; 347 IU/l) than for intravenous Erwinia administrations (159 IU/l). This prospective, multicentre study shows that monitoring of ASNase activity during treatment of children with ALL and NHL is feasible and informative. Treatment with Erwinia ASNase warrants close monitoring and optimally adherence to a 2-day interval of IM administrations.     

Dose reduction of asparaginase under pharmacokinetic and pharmacodynamic control during induction therapy in children with acute lymphoblastic leukaemia

The enzyme asparaginase is an important element in the therapy of acute lymphoblastic leukaemia (ALL). The usual asparaginase dose as prescribed in the ALL-BFM-86/90 treatment protocol for the therapy of ALL is 10 000 IU/m² at 3 d intervals and had been developed on the basis of the E. coli asparaginase preparation Crasnitin^TM from the Bayer company. Using the described schedule the E. coli asparaginase preparation from the Medac company shows significantly higher biological activity than the Bayer preparation. These findings prompted an attempt to reduce the dose of the Asparaginase medac^TM under careful pharmacokinetic and pharmacodynamic monitoring. At the first step of dose reduction in ALL treatment protocol I, 11 children received 5000 IU/m² of Asparaginase medac^TM. Another 15 children were given 2500 IU/m² of the enzyme at the second step of dose reduction. Prior to each asparaginase dose, blood samples were taken to determine amino acids and trough enzyme activity. Concurrent with the asparaginase monitoring, the coagulation parameters were measured. 96% of samples from the first step of dose reduction (5000 IU/m² every third day) showed complete L-asparagine depletion (<0.1 μM ), the median trough enzyme acitivity was 265 IU/l. At the second step of dose reduction (2500 IU/m²) complete L-asparagine depletion was seen in 97% of samples, and the median trough enzyme acitivity was 102 IU/l. Cerebrospinal fluid (CSF) depletion was complete in all samples tested (11/11). We concluded that an Asparaginase medac^TM dose reduced from the usual 10000 IU/m² down to 5000 IU/m² or 2500 IU/m², applied at 3 d intervals, was sufficient to achieve complete L-asparagine depletion in serum. Changes of the fibrinogen levels was significantly less pronounced in the group on 2500 IU.     

Hyperlipidemia in Iranian liver transplant recipients: prevalence and risk factors

Background Hyperlipidemia is a metabolic complication after liver transplantation (LT). The aim of this study was to investigate the prevalence and risk factors for developing hyperlipidemia in patients who underwent LT in the Shiraz Organ Transplantation Center. Methods Our patients were 170 liver recipients who underwent LT from 1994 to 2006 in the Organ Transplantation Center of the Shiraz University of Medical Sciences. To perform this study we administered questionnaires, including information about age, sex, body mass index (BMI), underlying liver disease, graft type, immunosuppressive medications, and serum levels of triglycerides and cholesterol, before and 6 months after LT. Serum triglyceride and cholesterol levels were considered elevated if they were >150 mg/dl and >250 mg/dl, respectively. Data were analyzed with SPSS software. Results There were 108 male and 62 female patients, with a mean age of 31.4 ± 13.3 years, and the mean duration of follow-up was 25.9 ± 23.5 months. The average pretransplant serum triglyceride and cholesterol (mean of individual means) levels were 104.6 ± 73.2 and 109.5 ± 51.5 mg/dl, respectively, and the average posttransplant levels were 230.1 ± 131 and 185 ± 77 mg/dl, respectively. Six months after LT, 119 (70%) and 26 (15.3%) patients developed hypertriglyceridemia and hypercholesterolemia, respectively. Age, sex, BMI, and underlying liver disease were not predictors of hypertriglyceridemia or hypercholesterolemia (P > 0.05). Posttransplant hypertriglyceridemia was significantly more common in patients receiving tacrolimus than in those receiving cyclosporine (P = 0.040), but posttransplant hypercholesterolemia had no significant correlation with type of immune suppression (P > 0.05). Conclusions Hyperlipidemia was common after LT, and hypertriglyceridemia was more common than hypercholesterolemia. Among all risk factors, tacrolimus therapy was correlated with development of hypertriglyceridemia after LT.     

Association between isolated hypercholesterolemia, isolated hypertriglyceridemia and coronary artery disease in south Indian type 2 diabetic patients

Very high prevalence rates of coronary artery disease have been reported among Indians. The aim of this study was to determine the relative importance of isolated hypercholesterolemia, isolated hypertriglyceridemia, isolated high low-density lipoprotein and isolated low high-density lipoprotein in coronary artery disease among South Indian type 2 diabetic subjects. The study group comprised of 17,885 type 2 diabetic patients attending our institute. A history of documented myocardial infarction was considered as the diagnostic criteria for coronary artery disease. Isolated hypercholesterolemia was defined as serum cholesterol over 200 mg/dL with normal serum triglyceride levels (< or = 200 mg/dL); isolated hypertriglyceridemia was defined as serum triglyceride level over 200 mg/dL with normal serum cholesterol levels (< or = 200 mg/dL). Isolated low high-density lipoprotein was defined as one below 35 mg/dL with normal serum triglyceride levels. Isolated high low-density lipoprotein cholesterol was defined as one over 150 mg/dL with normal serum triglyceride levels. Normolipidemia was defined as serum cholesterol and serum triglyceride both upto 200 mg/dL, high-density lipoprotein 35 mg/dL or above and low-density lipoprotein upto 150 mg/dL. The prevalence of coronary artery disease was significantly high among patients with isolated hypercholesterolemia (4.1%; p < 0.001), isolated high low-density lipoprotein (4.5%; p < 0.001) and isolated low high-density lipoprotein (3.9%; p = 0.005) compared to normolipidemic individuals (2.8%), but not in those with isolated hypertriglyceridemia (3.4%). The odds ratios for coronary artery disease increased with each quartiles of isolated cholesterol, isolated low-density lipoprotein cholesterol and total cholesterol to high-density lipoprotein ratio and reached statistical significance in the last quartile (p < 0.05). There was no significant increase in the odds ratios for coronary artery disease in relation to quartiles of isolated triglycerides. For isolated low high-density lipoprotein, when the last quartile was taken as the reference, the odds ratio for coronary artery disease in the first quartile reached statistical significance (p = 0.03). Multivariate regression analysis revealed age (odds ratio 1.06; p < 0.001), male sex (odds ratio 1.7; p < 0.001), hypercholesterolemia (odds ratio 1.26; p = 0.07) and high low-density lipoprotein levels (odds ratio 1.22; p = 0.043) to be strongly associated with coronary artery disease. Among South Indian type 2 diabetic subjects, serum isolated hypercholesterolemia and high low-density lipoprotein cholesterol but not isolated hypertriglyceridemia appear to be associated with coronary artery disease.     

Determining Triglyceride Reductions Needed for Clinical Impact in Severe Hypertriglyceridemia

Background

Patients with severe hypertriglyceridemia have an increased risk of cardiovascular disease and pancreatitis. Target triglyceride levels associated with clinical benefit for patients with severe hypertriglyceridemia are not currently known. This study evaluates the association between lower follow-up triglyceride levels and incidence of clinical events for patients with severe hypertriglyceridemia.

Methods

By using claims data from 2 large US healthcare databases, we conducted a retrospective cohort study and identified 41,210 adults with severe hypertriglyceridemia (triglycerides ≥500 mg/dL) between June 2001 and September 2010. The date of the first severe hypertriglyceridemia laboratory result was the index date. Patients were categorized into 1 of 5 triglyceride ranges (<200 mg/dL, 200-299 mg/dL, 300-399 mg/dL, 400-499 mg/dL, and ≥500 mg/dL) based on a follow-up triglyceride level assessed 6 to 24 weeks after initial triglyceride levels were measured. Adjusted Cox regression models were developed to evaluate the impact of follow-up triglyceride levels on rates of pancreatitis episodes and cardiovascular events.

Results

The mean age of patients was 50 years, 72% were male, and the mean follow-up was 825 days. Patients with severe hypertriglyceridemia with follow-up triglyceride levels <200 mg/dL experienced a lower rate of pancreatitis episodes (adjusted incidence rate ratio, 0.45; 95% confidence interval, 0.34-0.60) and cardiovascular events (adjusted incidence rate ratio, 0.71; 95% confidence interval, 0.64-0.78) with some clinical benefit in adults with severe hypertriglyceridemia with follow-up triglyceride levels 200 to 299 mg/dL and 300 to 399 mg/dL (P < .001 for trend).

Conclusions

We observed the greatest impact on clinical events among patients with severe hypertriglyceridemia with the lowest follow-up triglyceride levels.     

A randomized comparison of native Escherichia coli asparaginase and polyethylene glycol conjugated asparaginase for treatment of children with newly diagnosed standard-risk acute lymphoblastic leukemia: a Children's Cancer Group study

For this study, 118 children with standard-risk acute lymphoblastic leukemia (ALL) were given randomized assignments to receive native or pegylated Escherichia coli asparaginase as part of induction and 2 delayed intensification phases. Patients treated with pegaspargase had more rapid clearance of lymphoblasts from day 7 and day 14 bone marrow aspirates and more prolonged asparaginase activity than those treated with native asparaginase. In the first delayed intensification phase, 26% of native asparaginase patients had high-titer antibodies, whereas 2% of pegaspargase patients had those levels. High-titer antibodies were associated with low asparaginase activity in the native arm, but not in the pegaspargase arm. Adverse events, infections, and hospitalization were similar between arms. Event-free survival at 3 years was 82%. A population pharmacodynamic model using the nonlinear mixed effects model (NONMEM) program was developed that closely fit the measured enzyme activity and asparagine concentrations. Half-lives of asparaginase were 5.5 days and 26 hours for pegaspargase and native asparaginase, respectively. There was correlation between asparaginase enzymatic activity and depletion of asparagine or glutamine in serum. In cerebrospinal fluid asparagine, depletion was similar with both enzyme preparations. Intensive pegaspargase for newly diagnosed ALL should be tested further in a larger population.     

Consensus expert recommendations for identification and management of asparaginase hypersensitivity and silent inactivation

L-asparaginase is an integral component of therapy for acute lymphoblastic leukemia. However, asparaginase-related complications, including the development of hypersensitivity reactions, can limit its use in individual patients. Of considerable concern in the setting of clinical allergy is the development of neutralizing antibodies and associated asparaginase inactivity. Also problematic in the use of asparaginase is the potential for the development of silent inactivation, with the formation of neutralizing antibodies and reduced asparaginase activity in the absence of a clinically evident allergic reaction. Here we present guidelines for the identification and management of clinical hypersensitivity and silent inactivation with Escherichia coli- and Erwinia chrysanthemi- derived asparaginase preparations. These guidelines were developed by a consensus panel of experts following a review of the available published data. We provide a consensus of expert opinions on the role of serum asparaginase level assessment, indications for switching asparaginase preparation, and monitoring after change in asparaginase preparation.     

Lipid profile in an adult population in Guadeloupe

The purpose of this study was to provide data on lipid distribution and to investigate the association between hypercholesterolemia and other factors. A cross-sectional survey of insured subjects in an Health Center of Guadeloupe in 1999. Data from a consecutive series of 1 010 individuals aged 18 years and older, collected during a 3 month-period, were used. Standardized interviews and measurements of blood lipid abnormalities and other cardiovascular risk factors were carried out. Overall, 27% had elevated total cholesterol (TC) levels above 200 mg/dL, 11.7% had TC levels above 240 mg/dL, 18.1% had LDL-C levels above160 mg/dL, 12.5% had HDL-C below 35 mg/dL and 2.7% had triglyceride levels above 200 mg/dL. Isolated low HDL-C was found in 22% of the subjects and 10.8% had both TC above 240 mg/dL and LDL-C above 160 mg/dL. Only 22% of the subjects with high TC were aware of their diagnosis and 5% were treated. The risk of having hypercholesterolemia above 200 mg/dL was independently and significantly higher in case of hypertension, age above 45 in men or 55 in women, body mass index above 30 and familial history of dyslipidemia. These findings document the first report on dyslipidemia in Guadeloupe. It showed that the prevalence of hypercholesterolemia and hypertriglyceridemia was lower than in developed countries, but markedly higher than in Africa. Modifications of lifestyle and adapted therapeutics are necessary to decrease cardiovascular mortality.     

Prevalence of Dyslipidemia and Associated Factors in Obese Children and Adolescents

Objective:Childhood-onset obesity is associated with increased mortality and morbidity related to cardiovascular diseases (CVD) during adulthood. Dyslipidemia has a fundamental role in the pathogenesis of CVD. This study aimed to evaluate the prevalence of dyslipidemia and related factors among obese children and adolescents.Methods:Obese patients aged between 2 and 18 years were included in the study. Serum concentrations of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL-C), high-density lipoprotein (HDL-C), fasting glucose levels, insulin, thyroid-stimulating hormone (TSH), free thyroxine (fT4), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and liver ultrasound findings were evaluated retrospectively.Results:Among 823 obese patients, 353 (42.9%) met the dyslipidemia criteria: 21.7% had hypertriglyceridemia, 19.7% had low levels of HDL-C, 18.6% had hypercholesterolemia, and 13.7% had high levels of LDL-C. Older age and/or high body mass index (BMI) were related to increased prevalence of dyslipidemia. Hepatosteatosis was more common among dyslipidemic patients. The frequency of insulin resistance (IR) and of higher levels of ALT and TSH were also detected in dyslipidemic patients. Patients with both dyslipidemia and grade 2-3 hepatosteatosis had higher levels of ALT, AST and TSH and lower levels of fT4.Conclusion:Prevalence of dyslipidemia is high in obese children, and hypertriglyceridemia is in the foreground. Higher levels of IR and more apparent abnormal liver function test results are observed in the context of dyslipidemia and hepatosteatosis coexistence. Metabolic and hormonal alterations related with thyroid functions may also be associated with dyslipidemia and hepatosteatosis in obese patients.     

Genetic deficiency of apolipoprotein D in the mouse is associated with nonfasting hypertriglyceridemia and hyperinsulinemia

Apolipoprotein D (ApoD) is an atypical apolipoprotein with an incompletely understood function in the regulation of triglyceride and glucose metabolism. We have demonstrated that elevated ApoD production in mice results in improved postprandial triglyceride clearance. This work studies the role of ApoD deficiency in the regulation of triglyceride and glucose metabolism and its dependence on aging. We used ApoD knockout (ApoD-KO) mice of 3 and 21 months of age. Body weight and food intake were measured. Hepatic histology, triglyceride content, lipoprotein lipase levels, and plasma metabolites were studied. Phenotypic characterization of glucose metabolism was performed using glucose tolerance test. β-Cell mass, islet volume, and islet number were analyzed by histomorphometry. Apolipoprotein D deficiency results in nonfasting hypertriglyceridemia in young (P = .01) and aged mice (P = .002). In young ApoD-KO mice, hypertriglyceridemia was associated with 30% to 50% increased food intake in nonfasting and fasting conditions, respectively, without changes in body weight. In addition, lipoprotein lipase levels were reduced by 35% in adipose tissue (P = .006). In aged ApoD-KO mice, hypertriglyceridemia was not associated with changes in food intake or body weight, whereas hepatic triglyceride levels were reduced by 35% (P = .02). Furthermore, nonfasting plasma insulin levels were elevated by 2-fold in young (P = .016) and aged (P = .004) ApoD-KO mice, without changes in blood glucose levels, glucose tolerance, β-cell mass, or islet number. These findings underscore the importance of ApoD in the regulation of plasma insulin levels and triglyceride metabolism, suggesting that ApoD plays an important role in the pathogenesis of dyslipidemia.     

Pediatric Acute Lymphoblastic Leukemia: Efficacy and safety of recombinant E. coli-asparaginase in infants (less than one year of age) with acute lymphoblastic leukemia

The pharmacokinetics, pharmacodynamics, efficacy and safety of a new recombinant E. coli-asparaginase preparation were evaluated in infants (<1 year of age) with de novo acute lymphoblastic leukemia. Twelve patients were treated according to the INTERFANT-06 protocol and received up to 10,000 U/m² recombinant asparaginase as intravenous infusions on days 15, 18, 22, 25, 29 and 33 of remission induction treatment. The asparaginase dose was individually adjusted by protocol to 67% of the calculated dose for infants <6 months, and to 75% of the calculated dose for infants aged 6–12 months. The trough serum asparaginase activities observed were above 20, 50, and 100 U/L in 86%, 71%, and 51% of measured samples, respectively. Looking only at the data assessed 3 days after asparaginase infusion these percentages were 91%, 84%, and 74%, respectively. Asparagine was completely depleted in serum in all but one patient who was the youngest in the study. No anti-asparaginase antibodies were detected during this treatment phase. Observed adverse reactions are known to be possible and are labeled side effects of asparaginase treatment and chemotherapy. We conclude that the asparaginase dose regimen used in infants is safe and provides complete asparagine depletion for the desired time period in nearly all patients. Measured asparaginase trough serum levels justify the higher doses used in infants compared to in older children and show that 3-day intervals are preferred over 4-day intervals. (This trial was registered at www.clinicaltrialsregister.eu as EudraCT number 2008-006300-27).     

Results of successive EORTC-CLG 58 881 and 58 951 trials in paediatric T-cell acute lymphoblastic leukaemia (ALL)

Outcomes in childhood T-cell acute lymphoblastic leukaemia (T-ALL) are steadily improving due to intensive therapy. Between 1989 and 2008, 599 children with newly diagnosed T-ALL were enrolled in two successive European Organization for Research and Treatment of Cancer - Children's Leukaemia Group trials (58881 and 58951), both based on the Berlin-Frankfurt-Munster protocol and without cranial irradiation. In the latter trial induction chemotherapy was intensified. The most important randomizations were Medac Escherichia coli asparaginase versus Erwinia asparaginase in trial 58881, and dexamethasone (6 mg/m²/day) versus prednisolone (60 mg/m²/day) and prolonged versus conventional asparaginase duration in trial 58951. 8-year event-free survival (EFS) increased from 65·1% to 74·0% in trial 58951. Improvement was most profound for patients with white blood cell (WBC) counts <100 × 10⁹/l and “good responders” to prephase. Medac E. coli asparaginase was associated with longer EFS [hazard ratio (HR) 0·54, P = 0·0015] and overall survival (HR 0·51, P = 0·0018). Induction therapy with dexamethasone did not improve EFS compared to prednisolone. Remarkably, intensification of central nervous system (CNS)-directed therapy in trial 58951 resulted in fewer bone marrow relapses, while the incidence of CNS relapses remained low. In summary, we showed that adequate asparaginase therapy, intensified induction treatment and intensification of CNS-directed chemotherapy can result in an improvement of outcome in T-ALL patients with good prephase response and initial WBC counts <100 × 10⁹/l, representing approximately 50% of T-ALL patients.     

Treatment of hypertriglyceridemia with para-aminosalicylic acid-C: A possible mechanism of action

The effect of para-aminosalicylic acid-C (PAS-C, 8 g/day) on lipid metabolism was studied on a metabolic ward in nine subjects with primary endogenous hypertriglyceridemia. During 2 wk on a basal isocaloric liquid formula diet (40% fat, 45% carbohydrate), PAS-C reduced plasma triglyceride (?41.9 ± 18.9%, p < .01, $\text{x}$ ± SD), cholesterol (?22.8 ± 12.9%, p < .005), and a very low density lipoprotein triglyceride (p < .001) and cholesterol (p < .01) levels without changing the cholesterol content of low density or high density lipoproteins. Similar effects occurred on a fat-free, 85% carbohydrate diet. Decreases in very low density lipoproteins correlated with changes in both total triglyceride (r = .99, p < .01) and cholesterol (r = .70, p < .05). Treatment with PAS-C reduced the plasma triglyceride removal rate related to lipoprotein lipase (?14.6 ± 14.1%, p < .02), but did not alter plasma postheparin lipolytic activity or the apparent Km for substrate-enzyme interaction. Kinetic data obtained during the prolonged heparin infusion fit the linearized Michaelis-Menten model for subjects with endogenous hypertriglyceridemia. The reduction in the plasma triglyceride concentration during PAS-C treatment was a function of the decrease in triglyceride removal rate (r = .74, p < .025) without alternation in the maximal removal capacity related to lipoprotein lipase. This suggests that under the steady state conditions of these studies, the decrease in plasma triglyceride concentration was due to a reduction in endogenous triglyceride production. Free fatty acid metabolism, glucose homeostasis, fat absorption, and thyroid function did not change. These results suggest that PAS-C lowers plasma triglyceride and cholesterol levels in hypertriglyceridemic subjects by reducing endogenous very low density lipoprotein production and/or secretion into the circulation.     

Decline of postheparin plasma lipoprotein lipase in acromegalic patients

Lipoprotein lipase and hepatic triglyceride lipase in postheparin plasma were measured in seven patients with active acromegaly by an immunochemical method utilizing antiserum prepared against hepatic triglyceride lipase. A mild or moderate hypertriglyceridemia was shown, with plasma triglyceride concentrations between 156 and 544 mg/dl. Lipoprotein lipase was found to be decreased in all patients (p < 0.001). Hepatic triglyceride lipase was also low in these patients (p < 0.001). We speculate that acromegalic hypertriglyceridemia is mediated, at least in part, by the decline in lipoprotein lipase and possibly by the decline in hepatic triglyceride lipase activities.     

Pharmacokinetic dose adjustment of Erwinia asparaginase in protocol II of the paediatric ALL/NHL-BFM treatment protocols

Native forms of asparaginase stem from different biological sources. Previously reported data from children treated with Erwinase showed significantly lower trough levels and pharmacokinetic dose intensity than after E. coli-derived preparations. Hence, schedule optimization was initiated to achieve relevant serum activities. 21 children on reinduction therapy received Erwinase on Mondays, Wednesdays and Fridays for 3 weeks (9 x 20000 IU/m2 i.v.) instead of 4x 10 000IU/m2 of E. coli asparaginase (twice weekly for 2 weeks). Asparaginase trough activities were measured as the primary parameter, targeting 100-200 IU/I after 2 d and >50 IU/l after 3 d. Concurrently, asparagine trough concentrations were monitored. The mean trough activity was 156+/-99 IU/l, with 2/108 samples showing no detectable activity. Regarding trough levels per individual (three or more measurements/patient), means ranged from 52+/-29 to 276+/-114 IU/l (20 patients, 106 samples), with nine, six, and five children inside, below, and above the target range, respectively. The mean 3 d trough activity was 50+/-39 IU/l (20 patients, 51 samples). In 11 of these samples no activity was measurable. Mean trough activities calculated per individual ranged from < 20-84+/-30 IU/l (14 patients, 42 samples) with seven children below the target limit of 50 IU/l and asparagine concentrations <0.2 - 1.5microM. We concluded that an increased dose of 9x20000 IU/m2 of Erwinia asparaginase within 3 weeks resulted in a pharmacokinetic dose intensity comparable to former observations made with 4 x 10 000IU/m2 of the E. coli product Crasnitin which is no longer marketed. High interindividual variability and the phenomenon of 'silent' inactivation necessitate monitoring wherever possible.