Plasma D-asparagine and the D/L-serine ratio reflect chronic kidney diseases in children regardless of physique.

Biomarkers that accurately reflect renal function are essential in management of chronic kidney diseases (CKD). However, in children, age/physique and medication often alter established renal biomarkers. We studied whether amino acid enantiomers in body fluids correlate with renal function and whether they are influenced by physique or steroid medication during development. We conducted a prospective study of children 2 to 18 years old with and without CKD. We analyzed associations of serine/asparagine enantiomers in body fluids with major biochemical parameters as well as physique. To study consequences of kidney dysfunction and steroids on serine/asparagine enantiomers, we generated juvenile mice with uninephrectomy, ischemic reperfusion injury, or dexamethasone treatment. We obtained samples from 27 children, of which 12 had CKD due to congenital (n = 7) and perinatal (n = 5) causes. Plasma D-asparagine and the D/L-serine ratio had robust, positive linear associations with serum creatinine and cystatin C, and detected CKD with high sensitivity and specificity, uninfluenced by body size or biochemical parameters. In the animal study, kidney dysfunction increased plasma D-asparagine and the D/L-serine ratio, but dexamethasone treatment did not. Thus, plasma D-asparagine and the D/L-serine ratio can be useful markers for renal function in children.

Correlation of L-asp Activity, Anti-L-asp Antibody, Asn and Gln With Adverse Events Especially Anaphylaxis Risks in PEG-asp-Contained Regime Treated Pediatric ALL Patients.

OBJECTIVE: This study aimed to investigate the correlation of L-asparaginase (L-asp) activity, anti-L-asp antibody, asparagine and glutamine levels with the risks of adverse events (AEs), especially anaphylaxis, in pediatric acute lymphoblastic leukemia (ALL) patients who underwent polyethylene glycol-conjugated L-asp (PEG-asp)-contained treatment. METHODS: Plasma samples were collected from 91 pediatric ALL patients who underwent PEG-asp-contained treatment on the 7th day after drug administration. Plasma L-asp activity, anti-L-asp antibody level, asparagine level and glutamine level were detected. Meanwhile, AEs related to PEG-asp administration were recorded. RESULTS: AEs occurred in 13 (14.3%) patients, among which 7 (7.7%) patients had anaphylaxis, while another 6 patients had non-anaphylaxis AEs (including 4 (4.4%) patients who had acute pancreatitis, 1 (1.1%) patient who had abdominal pain and diarrhea, as well as 1 (1.1%) patient who had nausea and vomiting). L-asp activity was decreased, while asparagine and glutamine levels were increased in patients with AEs compared to patients without AEs, and ROC curves showed that they were correlated with higher AEs risk. Notably, further analyses revealed that L-asp activity, anti-L-asp antibody, asparagine and glutamine levels were highly correlated with anaphylaxis risk, but they were not associated with the risk of non-anaphylactic AEs. CONCLUSION: The measurement of L-asp activity, anti-L-asp antibody level, asparagine level and glutamine level might assist the prevention of anaphylaxis-related AEs in pediatric ALL patients who underwent PEG-asp-contained treatment.

Therapeutic Drug Monitoring of Asparaginase: Intra-individual Variability and Predictivity in Children With Acute Lymphoblastic Leukemia Treated With PEG-Asparaginase in the AIEOP-BFM Acute Lymphoblastic Leukemia 2009 Study.

BACKGROUND: Therapeutic drug monitoring (TDM) can identify patients with subtherapeutic asparaginase (ASNase) activity [silent inactivation (SI)] and prospectively guide therapeutic adaptation. However, limited intra-individual variability is a precondition for targeted dosing and the diagnosis of SI. METHODS: In the AIEOP-BFM acute lymphoblastic leukemia (ALL) 2009 trial, 2771 children with ALL were included and underwent ASNase-TDM in a central laboratory in Münster. Two biweekly administrations of pegylated ASNase during induction and a third dose during reinduction or the high-risk block, which was administered several weeks later, were monitored. We calculated (1) the incidence of SI; and (2) the predictivity of SI for SI after the subsequent administration. ASNase activities monitored during induction were categorized into percentiles at the respective sampling time points. These percentiles were used to calculate the intra-individual range of percentiles as a surrogate for intrapatient variability and to evaluate the predictivity of ASNase activity for the subsequent administration. RESULTS: The overall incidence of SI was low (4.9%). The positive predictive value of SI identified by one sample was ≤21%. Confirmation of SI by a second sample indicated a high positive predictive value of 100% for biweekly administrations, but not for administration more than 17 weeks later. Sampling and/or documentation errors were risks for misdiagnosis of SI. High intra-individual variability in ASNase activities, with ranges of percentiles over more than 2 quartiles and low predictivity, was observed in approximately 25% of the patients. These patients were likely to fail dose individualization based on TDM data. CONCLUSIONS: To use TDM as a basis for clinical decisions, standardized clinical procedures are required and high intra-individual variability should be taken into account. Details of the treatment are available in the European Clinical Trials Database at https://www.clinicaltrialsregister.eu/ctr-search/trial/2007-004270-43/DE.

Asparaginase activity levels and monitoring in patients with acute lymphoblastic leukemia.

Asparaginase is an integral component of multiagent chemotherapy regimens for the treatment of acute lymphoblastic leukemia (ALL). Adequate asparagine depletion is believed to be an important factor in achieving optimal therapeutic outcomes. Measurement of asparaginase activity allows practitioners to evaluate the potential effectiveness of therapy in real time. Asparaginase activity levels can be used to identify patients with silent inactivation and modify therapy in these patients. Patients with silent inactivation to asparaginase who are switched to therapy with an immunologically distinct asparaginase exhibit outcomes similar to patients who never developed silent inactivation. Despite these benefits, there exists no universally agreed-upon guideline for treatment adjustments based on asparaginase activity levels. The goal of this manuscript is to review the clinical evidence linking asparaginase activity levels to outcomes in patients with ALL and to provide an overview of how asparaginase activity levels may be used to guide treatment.

Sildenafil Treatment in Heart Failure With Preserved Ejection Fraction: Targeted Metabolomic Profiling in the RELAX Trial.

Importance: Phosphodiesterase-5 inhibition with sildenafil compared with a placebo had no effect on the exercise capacity or clinical status of patients with heart failure with preserved ejection fraction (HFpEF) in the PhosphodiesteRasE-5 Inhibition to Improve Clinical Status and Exercise Capacity in Diastolic Heart Failure with Preserved Ejection Fraction (RELAX) clinical trial. Metabolic impairments may explain the neutral results. Objective: To test the hypothesis that profiling metabolites in the RELAX trial would clarify the mechanisms of sildenafil effects and identify metabolites associated with clinical outcomes in HFpEF. Design, Setting, and Participants: Paired baseline and 24-week plasma samples of 160 stable outpatient individuals with HFpEF enrolled in the RELAX clinical trial were analyzed using flow injection tandem mass spectrometry (60 metabolites) and conventional assays (5 metabolites). Interventions: Sildenafil (n = 79) or a placebo (n = 81) administered orally at 20 mg, 3 times daily for 12 weeks, followed by 60 mg, 3 times daily for 12 weeks. Main Outcomes and Measures: The primary measure was metabolite level changes between baseline and 24 weeks stratified by treatments. Secondary measures included correlations between metabolite level changes and clinical biomarkers and associations between baseline metabolite levels and the composite clinical score. Results: No metabolites changed between baseline and 24 weeks in the group treated with a placebo; however, 7 metabolites changed in the group treated with sildenafil, including decreased amino acids (alanine and proline; median change [25th-75th], -38.26 [-100.3 to 28.19] and -28.24 [-56.29 to 12.08], respectively; false discovery rate-adjusted P = .01 and .03, respectively), and increased short-chain dicarboxylacylcarnitines glutaryl carnitine, octenedioyl carnitine, and adipoyl carnitine (median change, 6.19 [-3.37 to 14.18], 2.72 [-3 to 12.57], and 10.72 [-11.23 to 29.57], respectively; false discovery rate-adjusted P = .01, .04, and .05, respectively), and 1 long-chain acylcarnitine metabolite (palmitoyl carnitine; median change, 7.83 [-5.64 to 26.99]; false discovery rate-adjusted P = .03). The increases in long-chain acylarnitine metabolites and short-chain dicarboxylacylcarnitines correlated with increases in endothelin-1 and creatinine/cystatin C, respectively. Higher baseline levels of short-chain dicarboxylacylcarnitine metabolite 3-hydroxyisovalerylcarnitine/malonylcarnitine and asparagine/aspartic acid were associated with worse clinical rank scores in both treatment groups (ß, -96.60, P = .001 and ß, -0.02, P = .01; after renal adjustment, P = .09 and .02, respectively). Conclusions and Relevance: Our study provides a potential mechanism for the effects of sildenafil that, through adverse effects on mitochondrial function and endoplasmic reticulum stress, could have contributed to the neutral trial results in RELAX. Short-chain dicarboxylacylcarnitine metabolites and asparagine/aspartic acid could serve as biomarkers associated with adverse clinical outcomes in HFpEF.

Plasma asparaginase activity, asparagine concentration, and toxicity after administration of Erwinia asparaginase in children and young adults with acute lymphoblastic leukemia: Phase I/II clinical trial in Japan.

BACKGROUND: A phase I/II study of Erwinia asparaginase in Japanese children and young adults with acute lymphoblastic leukemia (ALL) was performed to investigate its activity and toxicity. PROCEDURE: Eligible patients were in remission and had developed allergy to Escherichia coli asparaginase. Erwina asparaginase was intramuscularly administrated on days 2, 5, 7, 9, 11, and 13. To measure the plasma l-asparagine concentration (PAC), amino acids were derivatized with Nα -(5-fluoro-2,4-dinitrophenyl)-l-leucinamide. RESULTS: Six consecutive patients completed the phase I study with 25,000 IU/m2 per dose without dose-limiting toxicity and 18 patients completed the phase II study with 25,000 IU/m2 per dose. Median age of 24 patients was 7.5 (range 2-16) years. The half-life of plasma asparaginase activity (PAA) was 16.9 ± 7.5 hr and the maximum PAA was 3.10 ± 1.47 IU/ml (n = 23, noncompartment model). PAA of 0.1 IU/ml or more was achieved in all 23 patients (100%) 48 hr and in 18 of 23 patients (78.3%) 72 hr after the first administration. During the 2-week study, 94.2% (65 of 69) of the 48-hr samples and 80.4% (37 of 46) of the 72-hr samples had PAA of 0.1 IU/ml or more. PAC less than 1.0 µM was achieved in 95.7% patients 48 and 72 hr after administration. PAC values in all the samples were greater than the limit of quantitation (0.0625 µM). Karnofsky performance status of all patients was good during the 2-week study. CONCLUSIONS: Erwinia asparaginase 25,000 IU/m2 per dose × six intramuscular administrations in 2 weeks was well tolerated, pharmacologically efficacious, and safe in Japanese patients with ALL/lymphoblastic lymphoma.

A Novel Multivariate Index for Pancreatic Cancer Detection Based On the Plasma Free Amino Acid Profile.

BACKGROUND: The incidence of pancreatic cancer (PC) continues to increase in the world, while most patients are diagnosed with advanced stages and survive <12 months. This poor prognosis is attributable to difficulty of early detection. Here we developed and evaluated a multivariate index composed of plasma free amino acids (PFAAs) for early detection of PC. METHODS: We conducted a cross-sectional study in multi-institutions in Japan. Fasting plasma samples from PC patients (n = 360), chronic pancreatitis (CP) patients (n = 28), and healthy control (HC) subjects (n = 8372) without apparent cancers who were undergoing comprehensive medical examinations were collected. Concentrations of 19 PFAAs were measured by liquid chromatography-mass spectrometry. We generated an index consisting of the following six PFAAs: serine, asparagine, isoleucine, alanine, histidine, and tryptophan as variables for discrimination in a training set (120 PC and matching 600 HC) and evaluation in a validation set (240 PC, 28 CP, and 7772 HC). RESULTS: Several amino acid concentrations in plasma were significantly altered in PC. Plasma tryptophan and histidine concentrations in PC were particularly low, while serine was particularly higher than that of HC. The area under curve (AUC) based on receiver operating characteristic (ROC) curve analysis of the resulting index to discriminate PC from HC were 0.89 [95% confidence interval (CI), 0.86-0.93] in the training set. In the validation set, AUCs based on ROC curve analysis of the PFAA index were 0.86 (95% CI, 0.84-0.89) for all PC patients versus HC subjects, 0.81 (95% CI, 0.75-0.86) for PC patients from stage IIA to IIB versus HC subjects, and 0.87 (95% CI, 0.80-0.93) for all PC patients versus CP patients. CONCLUSIONS: These findings suggest that the PFAA profile of PC was significantly different from that of HC. The PFAA index is a promising biomarker for screening and diagnosis of PC.

Asparaginase pharmacokinetics and implications of therapeutic drug monitoring.

Asparaginase is widely used in chemotherapeutic regimens for the treatment of acute lymphoblastic leukemia (ALL) and has led to a substantial improvement in cure rates, especially in children. Optimal therapeutic effects depend on a complete and sustained depletion of serum asparagine. However, pronounced interpatient variability, differences in pharmacokinetic properties between asparaginases and the formation of asparaginase antibodies make it difficult to predict the degree of asparagine depletion that will result from a given dose of asparaginase. The pharmacological principles underlying asparaginase therapy in the treatment of ALL are summarized in this article. A better understanding of the many factors that influence asparaginase activity and subsequent asparagine depletion may allow physicians to tailor treatment to the individual, maximizing therapeutic effect and minimizing treatment-related toxicity. Therapeutic drug monitoring provides a means of assessing a patient's current depletion status and can be used to better evaluate the potential benefit of treatment adjustments.

Increased N-glycosylation of Asn88 in serum pancreatic ribonuclease 1 is a novel diagnostic marker for pancreatic cancer.

Alterations of carbohydrate structures in cancer cells are the most promising targets for developing clinical diagnostic reagents. Pancreatic cancer is one of the most difficult cancers to diagnose because it lacks definitive symptoms. Two antibodies were raised against human pancreatic ribonuclease 1 that bind to the enzyme containing unglycosylated Asn(88), but not when its Asn(88) is N-glycosylated. Differential studies using these antibodies in immunoassays and Western blot analyses showed a significant increase in the serum levels of pancreatic ribonuclease 1 containing N-glycosylated Asn(88) in pancreatic cancer patients compared with normal human subjects. Focusing on the increase in an N-glycosylated Asn residue of serum pancreatic ribonuclease 1, specifically Asn(88), affords a new diagnostic marker for pancreatic cancer. This is the first report of a diagnostic cancer marker that takes advantage of the presence or absence of N-glycosylation at a specific Asn residue of a glycoprotein.

Glutamine depletion by crisantaspase hinders the growth of human hepatocellular carcinoma xenografts.

BACKGROUND: A subset of human hepatocellular carcinomas (HCC) exhibit mutations of ß-catenin gene CTNNB1 and overexpress Glutamine synthetase (GS). The CTNNB1-mutated HCC cell line HepG2 is sensitive to glutamine starvation induced in vitro with the antileukemic drug Crisantaspase and the GS inhibitor methionine-L-sulfoximine (MSO). METHODS: Immunodeficient mice with subcutaneous xenografts of the CTNNB1-mutated HCC cell lines HepG2 and HC-AFW1 were treated with Crisantaspase and/or MSO, and tumour growth was monitored. At the end of treatment, tumour weight and histology were assessed. Serum and tissue amino acids were determined by HPLC. Gene and protein expression were estimated with RT-PCR and western blot and GS activity with a colorimetric method. mTOR activity was evaluated from the phosphorylation of p70S6K1. RESULTS: Crisantaspase and MSO depleted serum glutamine, lowered glutamine in liver and tumour tissue, and inhibited liver GS activity. HepG2 tumour growth was significantly reduced by either Crisantaspase or MSO, and completely suppressed by the combined treatment. The combined treatment was also effective against xenografts of the HC-AFW1 cell line, which is Crisantaspase resistant in vitro. CONCLUSIONS: The combination of Crisantaspase and MSO reduces glutamine supply to CTNNB1-mutated HCC xenografts and hinders their growth.

Asparaginase Erwinia chrysanthemi (Erwinaze®): a guide to its use in acute lymphoblastic leukemia in the USA.

Asparaginase Erwinia chrysanthemi (Erwinaze®) is approved in the USA for use in patients with acute lymphoblastic leukemia (ALL) who have developed hypersensitivity to Escherichia coli-derived asparaginase. The approved regimen of intramuscular Erwinaze® was associated with sustained, clinically meaningful asparaginase activity in patients with ALL who had to discontinue treatment with pegaspargase (a pegylated formulation of E. coli asparaginase) because of hypersensitivity. Another study revealed that development of E. coli-derived asparaginase allergy and a switch to Erwinaze® maintained event-free survival in pediatric patients with newly diagnosed ALL. In a multicenter, compassionate-use trial, Erwinaze® was generally well tolerated, with the most commonly occurring adverse events including hypersensitivity, pancreatitis, fever, hyperglycemia, and increased transaminase levels. Subclinical hypersensitivity may result in the inactivation of asparaginase and affect treatment outcome; monitoring of serum asparaginase levels may be used to identify subclinical hypersensitivity.

Plant asparaginase-based asparagine biosensor for leukemia.

The present work aims at the development of plant asparaginase-based asparagine biosensor for leukemia. It is a novel diagnostic for monitoring asparagine levels in patients suffering from acute lymphoblastic leukemia (ALL). Various immobilization strategies have been applied to improve the stability of the asparaginase. The latest and updated information including some new techniques of immobilization related to L-asparaginase such as gelatin, agarose, agar, and calcium alginate methods are described in detail along with response time studies and comparative data. Furthermore these immobilization techniques have been applied for the detection of asparagine in normal and leukemia serum samples.

Pancreatic tumor sensitivity to plasma L-asparagine starvation.

OBJECTIVES: In this study, our aim was to test whether asparagine synthetase (ASNS) deficiency in pancreatic malignant cells can lead to sensitivity to asparagine starvation. We also investigated, in tumor-bearing mice, the efficacy of L-asparaginase entrapped in red blood cells (RBCs), a safe formulation, to induce asparagine depletion. METHODS: First, ASNS expression was evaluated by immunohistochemistry in sporadic pancreatic ductal adenocarcinoma. Then, 4 pancreatic carcinoma cell lines were examined by Western blot, immunocytochemistry, and cytotoxicity assay to L-asparaginase and in asparagine-free or reduced-asparagine media. Finally, mice bearing the most in vitro sensitive cell line received RBC-entrapped L-asparaginase to investigate the anticancer efficacy of serum asparagine depletion in vivo. RESULTS: Approximately 52% of pancreatic adenocarcinomas expressed no or low ASNS. The highest in vitro cytotoxicity to L-asparaginase or to reduced asparagine medium was observed with SW1990 line when ASNS expression was the lowest. In vivo sensitivity was confirmed for this cell line. CONCLUSIONS: Plasma asparagine depletion by RBC-entrapped L-asparaginase in selected patients having no low or no ASNS may be a promising therapeutic approach for pancreatic cancer.

Asparagine and aspartic acid concentrations in bone marrow versus peripheral blood during Berlin-Frankfurt-Münster-based induction therapy for childhood acute lymphoblastic leukemia.

A recent study suggested that mesenchymal cells in bone marrow (BM) may counteract l-asparaginase (L-Asp)-containing acute lymphoblastic leukemia (ALL) therapy by secreting asparagine. Herein, we compared asparagine and aspartic acid concentrations in the BM and peripheral blood (PB), in order to determine whether this in vitro observation could be translated into in vivo differences of amino acid levels between both compartments. Asparagine and aspartic acid concentrations in BM (days 15 and 33) and PB (days 12, 15 and 33) were measured during L-Asp-containing Berlin-Frankfurt-Münster (BFM)-based 5-week multi-agent remission induction therapy in 11 children diagnosed with ALL at the St. Anna Children's Hospital in Vienna, Austria. The level of asparagine depletion did not differ significantly between both compartments at any time point measured, but aspartic acid concentrations were significantly higher in BM than PB at days 15 and 33 (p < 0.05). In the context of the reported mesenchymal asparagine production in BM, an increased asparagine production may indeed take place in BM. However, it may be overcome by continuous action of L-Asp, which is mirrored by increased aspartic acid levels but unchanged low asparagine levels in BM, suggesting a higher BM turnover of asparagine generated by L-Asp during induction therapy.

Comparison of native E. coli and PEG asparaginase pharmacokinetics and pharmacodynamics in pediatric acute lymphoblastic leukemia.

Asparaginase (ASP) is used routinely in frontline clinical trials for the treatment of childhood acute lymphoblastic leukemia (ALL). The goals of this study were to assess the pharmacokinetics and pharmacodynamics of ASP and to mathematically model the dynamics between ASP and asparagine (ASN) in relapsed ALL. Forty children were randomized to receive either native or polyethylene glycolated (PEG) Escherichia coli ASP during reinduction therapy. Serial plasma ASP and ASN, cerebrospinal fluid (CSF) ASN, and serum anti-ASP antibody samples were collected. The ASP clearance was higher (P = 0.001) for native vs. PEG ASP. Patients with antibodies to PEG ASP had faster PEG ASP clearance (P = 0.004) than did antibody-negative patients. Patients who were positive for antibodies had higher CSF ASN concentrations than did those who were negative (P = 0.04). The modeling suggests that by modifying dosages, comparable ASN depletion is achievable with both preparations. At relapse, there were significant pharmacokinetic and pharmacodynamic differences attributable to ASP preparation and antibody status.

An isocratic fluorescence HPLC assay for the monitoring of l-asparaginase activity and l-asparagine depletion in children receiving E. colil-asparaginase for the treatment of acute lymphoblastic leukaemia.

A novel assay for the determination of l-asparaginase activity in human plasma is described that is based on the HPLC quantitation of l-aspartic acid produced during enzyme incubation. Methods for monitoring l-asparagine depletion are also described. Chromatography of l-aspartic acid, l-asparagine and l-homoserine (the internal standard) involved derivatization with o-pthaldialdehyde, then separation from other amino acids on a Phenomenex Luna C(18) column using a 1 mL/min flow rate and a mobile phase consisting of di-potassium hydrogen orthophosphate propionate buffer, pH 6, with 10% methanol and 10% acetonitrile. Fluoresence detection was at excitation/emission wavelengths of 357/455 nm. Under these conditions l-aspartic acid, l-asparagine and l-homoserine had retention times of 3.5, 9.8 and 17.7 min, respectively. The l-asparaginase assay was linear from 0.1 to 10 U/mL activity and interday precision and accuracy were less than 13%. The limit of quantitation was approximately 0.03 U/mL. The assay utility was established in 12 children who received E. coli l-asparaginase as treatment for acute lymphoblastic leukaemia.

FDA drug approval summary: pegaspargase (oncaspar) for the first-line treatment of children with acute lymphoblastic leukemia (ALL).

On July 24, 2006, the U.S. Food and Drug Administration granted approval to pegaspargase (Oncaspar; Enzon Pharmaceuticals, Inc., Bridgewater, NJ; hereafter, O) for the first-line treatment of patients with acute lymphoblastic leukemia (ALL) as a component of a multiagent chemotherapy regimen. O was previously approved in February 1994 for the treatment of patients with ALL who were hypersensitive to native forms of L-asparaginase. The trial supporting this new indication was an open label, randomized, multicenter clinical trial that enrolled 118 children (age, 1-9 years) with previously untreated, standard risk ALL. Patients received either native Escherichia coli asparaginase (Elspar; Merck, Whitehouse Station, NJ; hereafter, E) or O along with multiagent chemotherapy during remission induction and delayed intensification (DI) phases of treatment. O, at a dose of 2,500 IU/m(2), was administered i.m. on day 3 of the 4-week induction phase and on day 3 of each of two 8-week DI phases. E, at a dose of 6,000 IU/m(2), was administered i.m. three times weekly for nine doses during induction and for six doses during each DI phase. This study allowed direct comparison of O and E for asparagine depletion, asparaginase activity, and development of asparaginase antibodies. An unplanned comparison of event-free survival (EFS) was conducted to rule out a deleterious O efficacy effect. Following induction and DI treatment there was complete (0.03 IU/ml in O-treated subjects was greater than the number of days in E-treated subjects during both the induction and DI phases of treatment. There was no correlation, however, between asparaginase activity and serum asparagine levels, making the former determination less clinically relevant. Using the protocol-prespecified threshold for a positive result of >2.5 times the control, 7 of 56 (12%) O subjects tested at any time during the study demonstrated antiasparaginase antibodies and 16 of 57 (28%) E subjects tested at any time during the study had antiasparaginase antibodies. In both study arms EFS was in the range of 80% at 3 years. The most serious, sometimes fatal, O toxicities were anaphylaxis, other serious allergic reactions, thrombosis (including sagittal sinus thrombosis), pancreatitis, glucose intolerance, and coagulopathy. The most common adverse events were allergic reactions (including anaphylaxis), hyperglycemia, pancreatitis, central nervous system thrombosis, coagulopathy, hyperbilirubinemia, and elevated transaminases. Disclosure of potential conflicts of interest is found at the end of this article.

E. coli K-12 asparaginase-based asparagine biosensor for leukemia.

The present work aims at the development of a novel, diagnostic biosensor for monitoring asparagine levels in leukemia. Various immobilization strategies have been applied to improve the stability of the biocomponent (asparaginase). Response time studies have been carried out for different immobilization methods. Phenol Red indicator has been coimmobilized with asparaginase and color visualization approach has been optimized for various asparagine ranges. The detection limit of asparagine achieved with nitrocellulose membrane is 10(-1) M, with silicon gel is 10(-10)-10(-1) M, and with calcium alginate beads is 10(-9)-10(-1) M. Furthermore, the calcium alginate bead system of immobilization has been applied for the asparagine range detection in normal and leukemia serum samples.