L-asparagine depletion and L-asparaginase activity in children with acute lymphoblastic leukemia receiving i.m. or i.v. Erwinia C. or E. coli L-asparaginase as first exposure

The correlation of asparaginase enzyme activity levels after PEG-asparaginase administration with clinical characteristics and adverse effects in Chinese paediatric patients with acute lymphoblastic leukaemia

Studies on asparaginase enzyme activity (AEA) monitoring in Chinese patients receiving PEG-asparaginase remain limited. We monitored AEA in paediatric patients diagnosed with acute lymphoblastic leukaemia (ALL) and treated according to the Chinese Children's Cancer Group study protocols, CCCG-ALL-2015/CCCG-ALL-2020 protocols. We measured the AEA at days 7 ± 1 and 14 ± 1 and analysed their association with patient characteristics and PEG-asparaginase-related adverse effects (AEs). We measured 2147 samples from 329 patients. Mean AEA levels (interquartile range) were 931 iu/L (654-1174 iu/L) at day 7 ± 1 and 664 iu/L (463-860 iu/L) at day 14 ± 1. The AEA levels were higher in younger children and increased with the cumulative dose numbers. PEG-asparaginase inactivation rate was 19.1%, and the silent inactivation (SI) rate was 12.5%. Nine patients were identified with allergic-like reactions. Hypofibrinogenaemia, hypertriglyceridaemia, pancreatitis and thrombosis were associated with older age, whereas hypoglycaemia was associated with younger age. The risk of hypertriglyceridaemia and hypoglycaemia increased with cumulative dose numbers of PEG-asparaginase. Except for hypofibrinogenaemia, elevated AEA levels did not increase the risk of PEG-asparaginase-related AEs. Drug monitoring can be utilized as guidance for treatment decision-making. Individualizing asparaginase doses do not reduce toxicities. The treatment target of PEG-asparaginase remains to achieve sustained and adequate activity.

Pharmacokinetics of PEGasparaginase in Infants with Acute Lymphoblastic Leukemia

BACKGROUND

PEGasparaginase is known to be a critical drug for treating pediatric acute lymphoblastic leukemia (ALL), however, there is insufficient evidence to determine the optimal dose for infants who are less than one year of age at diagnosis. This international study was conducted to identify the pharmacokinetics of PEGasparaginase in infants with newly diagnosed ALL and gather insight into the clearance and dosing of this population.

METHODS

Infants with ALL who received treatment with PEGasparaginase were included in our population pharmacokinetic assessment employing non-linear mixed effects modelling (NONMEM).

RESULTS

68 infants with ALL, with a total of 388 asparaginase activity samples, were included. PEGasparaginase doses ranging from 400 to 3,663 IU/m2 were administered either intravenously or intramuscularly. A one-compartment model with time-dependent clearance, modeled using a transit model, provided the best fit to the data. Body weight was significantly correlated with clearance and volume of distribution. The final model estimated a half-life of 11.7 days just after administration, which decreased to 1.8 days 14 days after administration. Clearance was 19.5% lower during the post-induction treatment phase compared to induction.

CONCLUSION

The pharmacokinetics of PEGasparaginase in infants diagnosed under one year of age with ALL is comparable to that of older children (1-18 years). We recommend a PEGasparaginase dosing at 1,500 IU/m2 for infants without dose adaptations according to age, and implementing therapeutic drug monitoring as standard practice.

Expression and Biological Evaluation of an Engineered Recombinant L-asparaginase Designed by In Silico Method Based on Sequence of the Enzyme from Escherichia coli

Purpose

Medical usage of L-asparaginase (ASNase), the first-line of acute lymphoblastic leukemia treatment, is linked to allergic responses and toxicities, which necessitates the development of new bio-better ASNases. The aim of the current study was in silico design of a novel ASNase with predicted improved enzymatic properties using strategies encompassing sequence-function analysis of known ASNase mutants. Additionally, current study aimed to show that the new enzyme is active.

Methods

Based on 21 experimentally reported mutations for ASNase, a virtual library of mutated enzymes with all 7546 possible combinations of up to 4 mutations was generated. Three-dimensional models of proposed mutant enzymes were built and their in silico stabilities were calculated. The most promising mutant was selected for preparing a genetic construct suitable for expression of the designed ASNase in bacterial cells.

Results

Computational study predicted that Y176F/S241C double mutation of Escherichia coli ASNase may increase its folding stability. The designed ASNase was expressed in two different E. coli strains (Origami B(DE3) and BL21(DE3)pLysS) and then the soluble fractions prepared from the cell lysates of the host cells were used in enzyme activity assay. Results showed that enzyme activity of soluble fraction from Origami (95.4 ± 7.5 IU/0.1 mL) was four times higher than that of soluble fraction from pLysS (25.8 ± 2.5 IU/0.1 mL).

Conclusion

A novel functional double mutant ASNase with predicted improved enzymatic properties was designed and produced in E. coli. The results of the current study suggest a great commercial potential for the identified enzyme in pharmaceutical and industrial applications.

Back to the future: the amazing journey of the therapeutic anti-leukemia enzyme asparaginase Erwinia chrysanthemi

For several decades, asparaginase has been considered world-wide as an essential component of combination chemotherapy for the treatment of childhood acute lymphoblastic leukemia (ALL). Discovered over 60 years ago, two main unmanipulated asparaginase products originated from primary bacteria sources, namely Escherichia coli and Erwinia chrysanthemi, have been available for clinical use. A pegylated product of the Escherichia coli asparaginase was subsequently developed and is now the main product used by several international co-operative groups. The various asparaginase products all display the same mechanism of action (hydrolysis of circulating asparagine) and are associated with similar efficacy and toxicity patterns. However, their different pharmacokinetics, pharmacodynamics and immunological properties require distinctive modalities of application and monitoring. Erwinia chrysanthemi asparaginase was initially used as a first-line product, but subsequently became a preferred second-line product for children who experienced immunological reactions to the Escherichia coli asparaginase products. An asparaginase product displaying the same characteristics of the Erwinia chrysanthemi asparaginase has recently been produced by use of recombinant technology, thus securing a preparation available for use as an alternative, or as a back-up in case of shortages, for the non-recombinant product. The long journey of the Erwinia chrysanthemi asparaginase product as it has developed throughout the last several decades has made it possible for almost every child and adult with ALL to complete the asparaginase-based protocol treatment when an immunological reaction has occurred to any Escherichia coli asparaginase product.

Depletion of d- and l-asparagine in cerebrospinal fluid in acute lymphoblastic leukemia during PEGasparaginase therapy

BACKGROUND

l-Asparaginase hydrolyzes l-asparagine and not its enantiomer d-asparagine. Unlike l-asparagine, d-asparagine is nonessential for the survival of acute lymphoblastic leukemia (ALL) cells. Studies showed that serum asparagine is depleted below 0.5 μM in ≥96% of the patients during pegylated Escherichia coli l-asparaginase (PEGasparaginase) treatment; however, cerebrospinal fluid (CSF) asparagine levels are depleted in only 20%-30% of the patients. Thus far, studies only reported the total CSF asparagine (sum of d- and l-asparagine) concentrations. Data on the pharmacological goal, which is l-asparagine depletion, are lacking.

METHOD

Therefore, we studied this in 30 patients (95 samples) with newly diagnosed ALL. They received two doses of PEGasparaginase on day 4 and 18 in induction.

RESULTS

Median age at diagnosis was 5.7 years (range 1.5-17.1 years). d-Asparagine and l-asparagine concentrations (median (range)) before PEGasparaginase treatment were 0.038 (0.0-0.103) μM and 6.1 (1.82-11.5) μM, respectively. CSF l-asparagine concentrations were reduced by 85% (76%-100%) and approximately one-third of the patients (32%) had CSF l-asparagine depletion below 0.5 μM 11 days after the second PEGasparaginase dose administration. CSF d-asparagine and l-glutamine levels remained stable before and after administration of PEGasparaginase. The percentage of d-asparagine as a fraction of total asparagine (sum of d- and l-asparagine) was 0.62% before and 4.5% after PEGasparaginase treatment. No correlation was found between higher serum PEGasparaginase activity and CSF l-asparagine concentration.

CONCLUSION

l-Asparagine is not a better parameter than total asparagine in CSF due to the negligible amount of d-asparagine in the CSF before and after PEGasparaginase treatment.

A prospective, open-label, randomised, parallel design study of 4 generic formulations of intramuscular L-asparaginase in childhood precursor B-cell acute lymphoblastic leukaemia (ALL)

AIMS

L-asparaginase is an essential medicine for childhood ALL. The quality of generic L-asparaginase available in India is a matter of concern. We compared four commonly used generic formulations of L-asparaginase in India.

MATERIALS AND METHODS

We conducted a prospective, open-label, randomised trial of four generic formulations of asparaginase for the treatment of patients with newly diagnosed intermediate-risk B-ALL. Patients were randomly assigned in a 1:1:1:1 ratio to receive generic asparaginase at a dose of at 10,000 IU/m 2 on days 9, 12, 15, and 18 of a 35-day cycle (Induction treatment). The primary end points were to determine the difference in the asparaginase activity and asparagine depletion. Historical patients who received L-asparaginase Medac (innovator) served as controls.

RESULTS

A total of 48 patients underwent randomization; 12 patients each in the four arms. Failure to achieve predefined activity threshold of 100 IU/L was observed in 9/40 samples of Generic A (22·5%), 23/40 of Generic B (57·5%), and 43/44 (98%) each of Generic C and D. All 27 samples from seven historical patients who were administered Medac had activity > 100 IU/L. The average activity was significantly higher for Genericm A, 154 (70·3, 285·4) IU/L followed by Generic B 84·5(44·2, 289·1) IU/L, Generic C 45(14·4, 58·4) IU/L, and Generic D 20·4(13, 35) IU/L. Only 6 patients had asparaginase activity > 100 IU/L on each of the four occasions (Generic A = 5; Generic B = 1), and none of them developed Anti-Asparaginase Antibodies (AAA). On the other hand, AAA was observed in 12/36 patients who had at least one level < 100 IU/L (P < 0·05): Generic A 3/5, Generic B = 3/9, Generic D (4/11), and Generic C (5/11).

CONCLUSION

Generic A and B had better trough asparaginase activity compared to Generic D and C. Overall, generic formulations had lower asparaginase activity which raises serious clinical concerns regarding their quality. Until strict regulatory enforcement improves the quality of these generics, dose adaptive approaches coupled with therapeutic drug monitoring need to be considered.

Evaluation of PEG-L-asparaginase in asparagine suppression and anti-drug antibody development in healthy Beagle dogs: A multi-phase preclinical study

L-asparaginase is a frequently used drug in the treatment of canine malignant lymphoma. Since production and availability of native E. coli-derived L-asparaginase are limited, PEG-L-asparaginase (PEG-ASP) is an alternative. However, recommended doses and dosing intervals are mainly empirically determined. A multi-phase clinical dose-finding study with seven healthy Beagle dogs was conducted to find the minimum effective dose and, potentially, a dosing interval for PEG-ASP in dogs. Plasma concentrations of amino acids and PEG-ASP activity were measured at various time points after administration of different doses of PEG-ASP. Anti-PEG and anti-asparaginase antibody titres were measured. Administration of 10 IU/kg PEG-ASP resulted in asparagine depletion in all dogs, albeit for various durations: for 9 days in all dogs, 15 days in five dogs, 21 days in three dogs and 29 days in one dog. Asparagine suppression occurred at PEG-ASP plasma concentrations < 25 IU/L. Subsequent administrations of a second and third dose of 20 IU/kg and 40 IU/kg PEG-ASP resulted in asparagine suppression at < 9 days in five dogs, accompanied by the development of antibodies against PEG and L-asparaginase. Two dogs with prolonged asparagine suppression after the second and third administration did not develop antibodies. Marked individual variation in the mechanism and duration of response to PEG-ASP was noted. Antibody formation against PEG-ASP was frequently observed and sometimes occurred after one injection. This study suggests that PEG-ASP doses as high as the currently used dose of 40 IU/kg might not be needed in treatment of canine malignant lymphoma.

Current Use of Asparaginase in Acute Lymphoblastic Leukemia/Lymphoblastic Lymphoma

Pediatric Acute Lymphoblastic Leukemia (ALL) cure rates have improved exponentially over the past five decades with now over 90% of children achieving long-term survival. A direct contributor to this remarkable feat is the development and expanded understanding of combination chemotherapy. Asparaginase is the most recent addition to the ALL chemotherapy backbone and has now become a hallmark of therapy. It is generally accepted that the therapeutic effects of asparaginase is due to depletion of the essential amino acid asparagine, thus occupying a unique space within the therapeutic landscape of ALL. Pharmacokinetic and pharmacodynamic profiling have allowed a detailed and accessible insight into the biochemical effects of asparaginase resulting in regular clinical use of therapeutic drug monitoring (TDM). Asparaginase's derivation from bacteria, and in some cases conjugation with a polyethylene glycol (PEG) moiety, have contributed to a unique toxicity profile with hypersensitivity reactions being the most salient. Hypersensitivity, along with several other toxicities, has limited the use of asparaginase in some populations of ALL patients. Both TDM and toxicities have contributed to the variety of approaches to the incorporation of asparaginase into the treatment of ALL. Regardless of the approach to asparagine depletion, it has continually demonstrated to be among the most important components of ALL therapy. Despite regular use over the past 50 years, and its incorporation into the standard of care treatment for ALL, there remains much yet to be discovered and ample room for improvement within the utilization of asparaginase therapy.

Novel Insights on the Use of L-Asparaginase as an Efficient and Safe Anti-Cancer Therapy

Simple Summary

L-asparaginase (L-ASNase) therapy is key for achieving the very high cure rate of pediatric acute lymphoblastic leukemia (ALL), yet its use is mostly confined to this indication. One main reason preventing the expansion of today’s FDA-approved L-ASNases to solid cancers is their high toxicity and side effects, which become especially challenging in adult patients. The design of optimized L-ASNase molecules provides opportunities to overcome these unwanted toxicities. An additional challenge to broader application of L-ASNases is how cells can counter the pharmacological effect of this drug and the identification of L-ASNases resistance mechanisms. In this review, we discuss recent insights into L-ASNase adverse effects, resistance mechanisms, and how novel L-ASNase variants and drug combinations can expand its clinical applicability, with a focus on both hematological and solid tumors.

Abstract

L-Asparaginase (L-ASNase) is an enzyme that hydrolyses the amino acid asparagine into aspartic acid and ammonia. Systemic administration of bacterial L-ASNase is successfully used to lower the bioavailability of this non-essential amino acid and to eradicate rapidly proliferating cancer cells with a high demand for exogenous asparagine. Currently, it is a cornerstone drug in the treatment of the most common pediatric cancer, acute lymphoblastic leukemia (ALL). Since these lymphoblasts lack the expression of asparagine synthetase (ASNS), these cells depend on the uptake of extracellular asparagine for survival. Interestingly, recent reports have illustrated that L-ASNase may also have clinical potential for the treatment of other aggressive subtypes of hematological or solid cancers. However, immunogenic and other severe adverse side effects limit optimal clinical use and often lead to treatment discontinuation. The design of optimized and novel L-ASNase formulations provides opportunities to overcome these limitations. In addition, identification of multiple L-ASNase resistance mechanisms, including ASNS promoter reactivation and desensitization, has fueled research into promising novel drug combinations to overcome chemoresistance. In this review, we discuss recent insights into L-ASNase adverse effects, resistance both in hematological and solid tumors, and how novel L-ASNase variants and drug combinations can expand its clinical applicability.

L-asparaginase mediated therapy in L-asparagine auxotrophic cancers: A review

Microbial L-asparaginase is the most effective first-line therapeutic used in the treatment protocols of paediatric and adult leukemia. Leukemic cell's auxotrophy for L-asparagine is exploited as a therapeutic strategy to mediate cell death through metabolic blockade of L-asparagine using L-asparaginase. Escherichia coli and Erwinia chrysanthemi serve as the major enzyme deriving sources accepted in clinical practise and the enzyme has bestowed improvements in patient outcomes over the last 40 years. However, an array of side effects generated by the native enzymes due to glutamine co-catalysis and short serum stays augmenting frequent dosages, intended a therapeutic switch towards the development of biobetter alternatives for the enzyme including the formulations resulting in sustained local depletion of L-asparagine. In addition, the treatment with L-asparaginase in few cancer types has proven to elicit drug-induced cytoprotective autophagy mechanisms and therefore warrants concern. Although the off-target glutamine hydrolysis has been viewed in contributing the drug-induced secondary responses in cells deficient with asparagine synthetase machinery, the beneficial role of glutaminase-asparaginase in proliferative regulation of asparagine prototrophic cells has been looked forward. The current review provides an overview on the enzyme's clinical applications in leukemia and possible therapeutic implications in other solid tumours, recent advancements in drug formulations, and discusses the aspects of two-sided roles of glutaminase-asparaginases and drug-induced cytoprotective autophagy mechanisms.

How much asparaginase is needed for optimal outcome in childhood acute lymphoblastic leukaemia? A systematic review

This review focuses on asparaginase, a key component of childhood acute lymphoblastic leukaemia (ALL) treatment since the 1970s. This review evaluates how much asparaginase is needed for optimal outcome in childhood ALL. We provide an overview of asparaginase dose intensity, i.e. duration of total cumulative exposure in weeks and level of exposure reflected by dose and/or asparaginase activity level, and the corresponding outcome. We systematically searched papers published between January 1990 and March 2021 in the PubMed and MEDLINE databases and included 20 papers. The level and duration of exposure were based on the pharmacokinetic profile of the drug and the assumption that trough asparaginase activity levels of ≥100 IU/L should be achieved for complete l-asparagine depletion. The statistical meta-analysis of outcomes was not performed because different outcome measures were used. The level of exposure was not associated with the outcome as long as therapeutic asparaginase activity levels of ≥100 IU/L were reached. Conflicting results were found in the randomised controlled trials, but all truncation studies showed that the duration of exposure (expressed as weeks of l-asparagine depletion) does affect the outcome; however, no clear cutoff for optimal exposure duration was determined. Optimal exposure duration will also depend on immunophenotype, (cyto)genetic subgroups, risk group stratification and backbone therapy.

Improved pharmacokinetic and pharmacodynamic profile of a novel PEGylated native Erwinia chrysanthemi L-Asparaginase

Introduction. Erwinase® (native Erwinia chrysanthemi L-Asparaginase (nErA)) is an approved second-line treatment for acute lymphoblastic leukaemia (ALL) in children and adolescents, who develop hypersensitivity or neutralising antibodies to E.coli derived L-Asparaginases (ASNases). However, nErA has a short in vivo half-life requiring frequent dosing schedules in patients. In this study, nErA was covalently conjugated to PEG molecules with the aim of extending its half-life in vivo. Methods. Firstly, efficacy of this novel product PEG-nErA was investigated on human ALL cell lines (Jurkat, CCRF-CEM and CCRF-HSB2), in vitro. Secondly, its pharmacokinetic (PK) and pharmacodynamic (PD) characteristics were determined, in vivo (12 rats in each group). Results. It was found that the specific activity (U/mg of enzyme) and the kinetic constant (K_M) of nErA remained unaltered post PEGylation. PEG-nErA was shown to have similar cytotoxicity to nErA (IC₅₀: 0.06–0.17 U/mL) on human ALL cell lines, in vitro. Further, when compared to nErA, PEG-nErA showed a significantly improved half-life in vivo, which meant that L-Asparagine (Asn) levels in plasma remained depleted for up to 25 days with a four-fold lower dose (100 U/kg) compared with 72 h for nErA at 400 U/kg dose. Conclusion. Overall, this next generation product PEG-nErA (with improved PK and PD characteristics compared to nErA) would bring a significant advantage to the therapeutic needs of ALL patients and should be further explored in clinical trials.

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 treatment. A population pharmacokinetic (popPK) model was developed, identifying patient characteristics explaining these variabilities. Patients (n=92) were treated according to the DCOG ALL-11 protocol, using therapeutic drug monitoring to individualize the PEGasparaginase doses. Non-linear mixed effects modeling (NONMEM) was used to analyze the 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 time-dependent clearance adequately described the popPK. Normalization of clearance and volume of distribution by body surface are (BSA) reduced inter-individual variability. Clearance was 0.084 L/day/m2 for 12.7 days, increasing with 0.082 L/day/m2/day thereafter. Clearance was 38% higher during an infection, and 11-19% higher during induction treatment than intensification and maintenance (p<0.001). Targeting 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 BSA, treatment phase and the occurrence of an infection. With this popPK model, PEGasparaginase treatment can be individualized further, taking into account these covariates and the dosing guidelines provided.

Higher plasma asparaginase activity after intramuscular than intravenous Erwinia asparaginase

It is unclear if dosing intervals for Erwinase can be extended with intramuscular (i.m.) versus intravenous (i.v.) dosing. Children with acute lymphoblastic leukemia received Erwinase at 30 000-42 000 IU/m² i.v. or i.m. I.m. Erwinase (n = 22) achieved activity above 0.1 IU/mL for longer than i.v. Erwinase (n = 33) (3.4 vs 2.9 days, P = 0.0007). With 30 000 IU/m² Monday, Wednesday, Friday, more patients achieved adequate concentrations over the weekend with i.m. vs i.v. dosing (P = 5 × 10^-36 ). A schedule with i.v. doses on Monday and Wednesday and i.m. doses on Friday of 30 000 IU/m² maintained activity > 0.1 IU/mL over the weekend in 80% of patients.

A comparison of asparaginase activity in generic formulations of E.coli derived L- asparaginase: In-vitro study and retrospective analysis of asparaginase monitoring in pediatric patients with leukemia

AIMS

L-asparaginase is an essential medicine in the treatment of pediatric acute lymphoblastic leukemia (ALL) and the quality of generic formulations is an area of concern. We compared nine generic formulations of L-asparaginase available in India with the innovator.

METHODS

The quality of formulations was assessed by measuring 72-hour trough asparaginase activity in children with ALL during induction following administration of 10,000 IU/m² of L-asparaginase. In-vitro analysis of the label claim was assessed by measuring activity of three generic formulations. Liquid chromatography-mass spectrometry (LC/MS) was used to determine the amount of host contaminant proteins (HCPs) in the formulations.

RESULTS

Between March 2015 to June 2018, 240 samples from 195 patients were analyzed. The number of samples analyzed ranged from 7-66 per generic brand (median: 18) and seven of the innovator. The proportion of generic formulations that failed to achieve a predefined clinical threshold activity of 50 IU/L ranged from 16.7% (2/12) to 84.9% (28/33) in the highest activity to lowest activity generic respectively. On other hand, all innovator samples had activity greater than 50 IU/L. In-vitro asparaginase activity in the three generic formulations tested ranged from 71.4-74.6% of the label claim (10,000 IU) compared to 93.5% for the innovator. LC/MS analysis of generic 5 identified 25 HCPs with a relative peptide count of 27.1% of the total peptides.

CONCLUSIONS

Generic formulations had lower asparaginase activity which raises serious clinical concerns regarding their quality. Until stringent regulatory enforcement improves the quality of these generics, dose adaptive strategies coupled with therapeutic drug monitoring need to be considered.

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.

Individualized Asparaginase Dosing in Childhood Acute Lymphoblastic Leukemia

PURPOSE

In the DCOG ALL-11 protocol, polyethylene glycol-conjugated Escherichia coli asparaginase (PEGasparaginase) and Erwinia asparaginase treatment of pediatric acute lymphoblastic leukemia are individualized with therapeutic drug monitoring (TDM). The efficacy of TDM and its effect on asparaginase-associated toxicity are reported.

PATIENTS AND METHODS

After induction with 3 fixed intravenous doses of 1,500 IU/m² PEGasparaginase, medium-risk patients (n = 243) received 14 individualized doses that targeted trough levels of 100-250 IU/L, standard-risk patients (n = 108) received 1 individualized dose, and high-risk patients (n = 18) received 2-5 fixed administrations (1,500 IU/m²). After a neutralizing hypersensitivity reaction, patients were started with 20,000 IU/m² Erwinia asparaginase 3 times per week, and l-asparagine was measured to monitor asparaginase efficacy. Several asparaginase-associated toxicities were studied.

RESULTS

The final median PEGasparaginase dose was lowered to 450 IU/m². Overall, 97% of all trough levels of nonallergic patients were > 100 IU/L. Asparagine was < 0.5 μM in 96% and 67% of the PEGasparaginase and Erwinia asparaginase levels > 100 IU/L, respectively. Ten percent developed a neutralizing hypersensitivity reaction to PEGasparaginase, of which 40% were silent inactivations. The cumulative incidence of grade 3-4 pancreatitis, central neurotoxicity, and thromboses was 12%, 4%, and 6%, respectively, and not associated with asparaginase activity levels. During medium-risk intensification, 50% had increased ALT and 3% hyperbilirubinemia (both grade 3/4 and correlated with asparaginase activity levels), and 37% had grade 3/4 hypertriglyceridemia. Hypertriglyceridemia occurred less in intensification compared with ALL-10 (37% v 47%), which is similar to ALL-11 but with higher asparaginase levels during intensification.

CONCLUSION

TDM of asparaginase results in a significant reduction of the PEGasparaginase dose with adequate asparaginase activity levels and sufficient asparagine depletion. In addition, with TDM, silent inactivation and allergic-like reactions were identified. However, the effect of reduced asparaginase activity levels on toxicity is limited.

Reduced vs. standard dose native E. coli-asparaginase therapy in childhood acute lymphoblastic leukemia: long-term results of the randomized trial Moscow-Berlin 2002

Purpose

Favorable outcomes were achieved for children with acute lymphoblastic leukemia (ALL) with the first Russian multicenter trial Moscow–Berlin (ALL-MB) 91. One major component of this regimen included a total of 18 doses of weekly intramuscular (IM) native Escherichia coli-derived asparaginase (E. coli-ASP) at 10000 U/m² during three consolidation courses. ASP was initially available from Latvia, but had to be purchased from abroad at substantial costs after the collapse of Soviet Union. Therefore, the subsequent trial ALL-MB 2002 aimed at limiting costs to a reasonable extent and also at reducing toxicity by lowering the dose for standard risk (SR−) patients to 5000 U/m² without jeopardizing efficacy.

Methods

Between April 2002 and November 2006, 774 SR patients were registered in 34 centers across Russia and Belarus, 688 of whom were randomized. In arm ASP-5000 (n = 334), patients received 5000 U/m² and in arm ASP-10000 (n = 354) 10 000 U/m² IM.

Results

Probabilities of disease-free survival, overall survival and cumulative incidence of relapse at 10 years were comparable: 79 ± 2%, 86 ± 2% and 17.4 ± 2.1% (ASP-5000) vs. 75 ± 2% and 82 ± 2%, and 17.9 ± 2.0% (ASP-10000), while death in complete remission was significantly lower in arm ASP-5000 (2.7% vs. 6.5%; p = 0.029).

Conclusion

Our findings suggest that weekly 5000 U/m²E. coli-ASP IM during consolidation therapy are equally effective, more cost-efficient and less toxic than 10000 U/m² for SR patients with childhood ALL.

Electronic supplementary material

The online version of this article (10.1007/s00432-019-02854-x) contains supplementary material, which is available to authorized users.

Microbes Producing L-Asparaginase free of Glutaminase and Urease isolated from Extreme Locations of Antarctic Soil and Moss

L-Asparaginase (L-asparagine aminohydrolase, E.C. 3.5.1.1) has been proven to be competent in treating Acute Lymphoblastic Leukaemia (ALL), which is widely observed in paediatric and adult groups. Currently, clinical L-Asparaginase formulations are derived from bacterial sources such as Escherichia coli and Erwinia chrysanthemi. These formulations when administered to ALL patients lead to several immunological and hypersensitive reactions. Hence, additional purification steps are required to remove toxicity induced by the amalgamation of other enzymes like glutaminase and urease. Production of L-Asparaginase that is free of glutaminase and urease is a major area of research. In this paper, we report the screening and isolation of fungal species collected from the soil and mosses in the Schirmacher Hills, Dronning Maud Land, Antarctica, that produce L-Asparaginase free of glutaminase and urease. A total of 55 isolates were obtained from 33 environmental samples that were tested by conventional plate techniques using Phenol red and Bromothymol blue as indicators. Among the isolated fungi, 30 isolates showed L-Asparaginase free of glutaminase and urease. The L-Asparaginase producing strain Trichosporon asahii IBBLA1, which showed the highest zone index, was then optimized with a Taguchi design. Optimum enzyme activity of 20.57 U mL-1 was obtained at a temperature of 30 °C and pH of 7.0 after 60 hours. Our work suggests that isolation of fungi from extreme environments such as Antarctica may lead to an important advancement in therapeutic applications with fewer side effects.

Asparagine levels in the cerebrospinal fluid of children with acute lymphoblastic leukemia treated with pegylated-asparaginase in the induction phase of the AIEOP-BFM ALL 2009 study

Asparagine levels in cerebrospinal fluid and serum asparaginase activity were monitored in children with acute lymphoblastic leukemia treated with pegylated-asparaginase. The drug was given intravenously at a dose of 2,500 IU/m² on days 12 and 26. Serum and cerebrospinal fluid samples obtained on days 33 and 45 were analyzed centrally. Since physiological levels of asparagine in the cerebrospinal fluid of children and adolescents are 4-10 μmol/L, in this study asparagine depletion was considered complete when the concentration of asparagine was ≤0.2 μmol/L, i.e. below the lower limit of quantification of the assay used. Over 24 months 736 patients (AIEOP n=245, BFM n=491) and 903 cerebrospinal fluid samples (n=686 on day 33 and n=217 on day 45) were available for analysis. Data were analyzed separately for the AIEOP and BFM cohorts and yielded superimposable results. Independently of serum asparaginase activity levels, cerebrospinal fluid asparagine levels were significantly reduced during the investigated study phase but only 28% of analyzed samples showed complete asparagine depletion while relevant levels, ≥1 μmol/L, were still detectable in around 23% of them. Complete cerebrospinal fluid asparagine depletion was found in around 5-6% and 33-37% of samples at serum asparaginase activity levels <100 and ≥ 1,500 IU/L, respectively. In this study cerebrospinal fluid asparagine levels were reduced during pegylated-asparaginase treatment, but complete depletion was only observed in a minority of patients. No clear threshold of serum pegylated-asparaginase activity level resulting in complete cerebrospinal fluid asparagine depletion was identified. The consistency of the results found in the two independent data sets strengthen the observations of this study. Details of the treatment are available in the European Clinical Trials Database at https://www.clin-icaltrialsregister.eu/ctr-search/trial/2007-004270-43/IT.

Plasma asparaginase activity and asparagine depletion in acute lymphoblastic leukemia patients treated with pegaspargase on Children's Oncology Group AALL07P4

The efficacy of asparaginase in acute lymphoblastic leukemia (ALL) is dependent on depletion of asparagine, an essential amino acid for ALL cells. The target level of plasma asparaginase activity to achieve asparagine depletion has been between 0.05 and 0.4 IU/mL. COG AALL07P4 examined the asparaginase activity and plasma and CSF asparagine concentration of pegaspargase when given intravenously in the treatment of NCI high risk ALL. Matched plasma asparaginase/asparagine levels of the clearance of 54 doses of pegaspargase given in induction or consolidation demonstrated that all patients who had a plasma asparaginase level >0.02 IU/mL had undetectable plasma asparagine. No difference was observed in CSF asparagine levels associated with matched plasma asparaginase levels of 0.02-0.049 versus 0.05-0.22 IU/mL (p = .25). Our data suggest that a plasma asparaginase activity level of 0.02 IU/mL can effectively deplete plasma asparagine. The data also indicate that the 95% CI for plasma asparagine depletion after a pegaspargase dose is 22-29 days. Clinical trial registration: clinicaltrials.gov identifier NCT00671034.

Development of L-Asparaginase Biobetters: Current Research Status and Review of the Desirable Quality Profiles

L-Asparaginase (ASNase) is a vital component of the first line treatment of acute lymphoblastic leukemia (ALL), an aggressive type of blood cancer expected to afflict over 53,000 people worldwide by 2020. More recently, ASNase has also been shown to have potential for preventing metastasis from solid tumors. The ASNase treatment is, however, characterized by a plethora of potential side effects, ranging from immune reactions to severe toxicity. Consequently, in accordance with Quality-by-Design (QbD) principles, ingenious new products tailored to minimize adverse reactions while increasing patient survival have been devised. In the following pages, the reader is invited for a brief discussion on the most recent developments in this field. Firstly, the review presents an outline of the recent improvements on the manufacturing and formulation processes, which can severely influence important aspects of the product quality profile, such as contamination, aggregation and enzymatic activity. Following, the most recent advances in protein engineering applied to the development of biobetter ASNases (i.e., with reduced glutaminase activity, proteolysis resistant and less immunogenic) using techniques such as site-directed mutagenesis, molecular dynamics, PEGylation, PASylation and bioconjugation are discussed. Afterwards, the attention is shifted toward nanomedicine including technologies such as encapsulation and immobilization, which aim at improving ASNase pharmacokinetics. Besides discussing the results of the most innovative and representative academic research, the review provides an overview of the products already available on the market or in the latest stages of development. With this, the review is intended to provide a solid background for the current product development and underpin the discussions on the target quality profile of future ASNase-based pharmaceuticals.

Personalized nanomedicine: a rapid, sensitive, and selective UV-vis spectrophotometry method for the quantification of nanostructured PEG-asparaginase activity in children's plasma

Purpose

PEGylated asparaginase (PEG-ASNase), which hydrolyzes asparagine to ammonia and aspartic acid, is an effective nanostructured antitumor agent for acute lymphoblastic leukemia (ALL). In order to monitor the activity of PEG-ASNase in plasma and design an individualization project, a rapid and sensitive method to determine PEG-ASNase activity in plasma using ultraviolet–visible spectrophotometry was established.

Methods

PEG-ASNase is commonly used in acute lymphoblastic leukemia. With Nessler’s reagent as the chromogenic reagent of ammonia, a stable yellow complex was produced. The units of enzyme activity were defined as micromoles of ammonia released per minute.

Results

Calibration curves fitted by plotting the OD at 450 nm of the Nessler product vs concentration were linear in the range of 27.8–1,111.0 IU/L with r²=0.999. The lower limit of quantification for PEG-ASNase activity in human plasma was 20 IU/L with good accuracy and precision. The intra- and interday precision (relative standard deviation) values were below 10% and accuracy ranged from 90% to 110% at all quality control levels. Analytical recoveries were determined between 90% and 110% for all quality control samples.

Conclusion

This study proved that the Nessler method is well validated and can be successfully applied in the determination of plasma samples in the clinical setting for patients with ALL. It takes personalized nanomedicine to an entirely new level.

Development of a UPLC-MS/MS method for the therapeutic monitoring of L-asparaginase

This study aimed to develop a UPLC-MS/MS method for determining plasma levels of L-aspartic acid and L-asparagine and the activity of L-asparaginase. L-aspartic acid, L-asparagine, and L-aspartic acid-2,3,3-d₃ were extracted from human plasma by protein precipitation with sulfosalicylic acid (30%, v/v). The plasma samples were analyzed using an Imtakt Intrada amino acid analysis column with 25 mM ammonium formate and 0.5% formic acid in acetonitrile as the mobile phase with step gradient method at a flow rate of 0.5 mL/min. The injection volume was 5 µL, and the total run time was 15 min. Inter- and intra-batch accuracies (%) ranged from 96.62–106.0% for L-aspartic acid and 89.85–104.8%, for L-asparagine, and the coefficient of variation (CV%) did not exceed 7%. The validation results for L-aspartic acid and L-asparagine satisfied the specified criterion, however, the results for L-asparaginase activity assay showed a borderline validity. This study could be a foundation for further development of therapeutic drug monitoring systems using UPLC-MS/MS.

Efficacy and safety of recombinant E. coli asparaginase in children with previously untreated acute lymphoblastic leukemia: A randomized multicenter study of the Dutch Childhood Oncology Group

BACKGROUND

The efficacy and safety of recombinant Escherichia coli-asparaginase (rASNase) was compared to native E.coli asparaginase (Asparaginase medac).

METHODS

One hundred and ninety-nine children with newly diagnosed acute lymphoblastic leukemia were randomized to receive one of both agents at a dose of 5,000 U/m² during induction (eight doses) and 10,000 U/m² during the postinduction phase (only high-risk patients; standard- and medium-risk patients received pegaspargase).

RESULTS

Median trough serum asparaginase activity levels were comparable between both groups; they ranged from 143 to 182 U/l during induction and were above the target value of 100 U/l. Complete asparagine depletion in serum was achieved in 97.9% of patients, with no significant differences between both groups. On day 33 (end of induction), only two (2%) evaluable patients in each group had measurable asparagine serum levels, and complete asparagine depletion in the cerebrospinal fluid was achieved in 98.8% and 93.6% of the patients with rASNase and Asparaginase medac, respectively. During induction, 2.1% and 5% of patients developed an allergic reaction to rASNase or Asparaginase medac, respectively. Approximately 41% of the patients in both groups had a clinical allergy or enzyme inactivation to the first dose of any asparaginase preparation in postinduction. A comparable proportion of patients in both groups developed anti-asparaginase antibodies (57%) during repeated administration of asparaginase. Minimal residual disease levels at the end of induction, 5-year event-free survival, and 5-year cumulative incidence of relapse did not differ between both groups.

CONCLUSION

The efficacy, safety, and immunogenicity of both asparaginase preparations are comparable. This trial was registered at www.clinicaltrials.gov as #NCT00784017; EudraCT number 2006-003180-31.

A cost analysis of individualized asparaginase treatment in pediatric acute lymphoblastic leukemia

BACKGROUND

Therapeutic drug monitoring (TDM) of asparaginase is necessary to respond to variability in asparaginase activity levels, detect silent inactivation, and distinguish between real allergies and allergic-like reactions with and without asparaginase neutralization, respectively. In this study, the costs of an individualized and fixed asparaginase dosing schedule were compared.

PROCEDURE

Patients, treated according to the Dutch Childhood Oncology Group ALL-11 protocol (individualized PEGasparaginase treatment, starting dose: 1,500 IU/m² ) or ALL-10 protocol (native Escherichia coli asparaginase followed by 2,500 IU/m² PEGasparaginase), were included. To focus on TDM of PEGasparaginase, the costs were also calculated excluding patients treated with Erwinia asparaginase and compared to a hypothetical protocol with a fixed dose of 1,500 IU/m² PEGasparaginase. Direct asparaginase-related medical costs, including costs for asparaginase use (calculated with the absolute dose), TDM, laboratory tests, daycare treatment, and outpatient clinic visits, were calculated.

RESULTS

Eighty-three ALL-10 patients and 51 ALL-11 patients were included. The asparaginase-related costs were 30.8% lower in ALL-11 than in ALL-10 ($29,048 vs. $41,960). The ALL-11 costs of nonallergic patients were 20.4% lower, when using TDM, than the hypothetical protocol with a fixed dose of 1,500 IU/m² ($13,178 vs. $16,551). TDM accounted for 12.4% of the costs. Including asparaginase waste, TDM in ALL-11 will be cost saving if three doses can be prepared out of one vial compared to a fixed dose of 1,500 IU/m² .

CONCLUSIONS

TDM of asparaginase is cost saving if calculated with the absolute asparaginase dose and will be if the waste is minimalized by preparing multiple doses out of one vial.

Prolonged versus standard native E. coli asparaginase therapy in childhood acute lymphoblastic leukemia and non-Hodgkin lymphoma: final results of the EORTC-CLG randomized phase III trial 58951

Asparaginase is an essential component of combination chemotherapy for childhood acute lymphoblastic leukemia and non-Hodgkin lymphoma. The value of asparaginase was further addressed in a group of non-very high-risk patients by comparing prolonged (long-asparaginase) versus standard (short-asparaginase) native E. coli asparaginase treatment in a randomized part of the phase III 58951 trial of the European Organization for Research and Treatment of Cancer Children's Leukemia Group. The main endpoint was disease-free survival. Overall, 1,552 patients were randomly assigned to long-asparaginase (775 patients) or short-asparaginase (777 patients). Patients with grade ≥2 allergy to native E. coli asparaginase were switched to equivalent doses of Erwinia or pegylated E. coli asparaginase. The 8-year disease-free survival rate (±standard error) was 87.0±1.3% in the long-asparaginase group and 84.4±1.4% in the short-asparaginase group (hazard ratio: 0.87; P=0.33) and the 8-year overall survival rate was 92.6±1.0% and 91.3±1.2% respectively (hazard ratio: 0.89; P=0.53). An exploratory analysis suggested that the impact of long-asparaginase was beneficial in the National Cancer Institute standard-risk group with regards to disease-free survival (hazard ratio: 0.70; P=0.057), but far less so with regards to overall survival (hazard ratio: 0.89). The incidences of grade 3-4 infection during consolidation (25.2% versus 14.4%) and late intensification (22.6% versus 15.9%) and the incidence of grade 2-4 allergy were higher in the long-asparaginase arm (30% versus 21%). Prolonged native E. coli asparaginase therapy in consolidation and late intensification for our non-very high-risk patients did not improve overall outcome but led to an increase in infections and allergy. This trial was registered at www.clinicaltrials.gov as #NCT00003728.

Different methodologies for sustainability of optimization techniques used in submerged and solid state fermentation

Optimization techniques are considered as a part of nature's way of adjusting to the changes happening around it. There are different factors that establish the optimum working condition or the production of any value-added product. A model is accepted for a particular process after its sustainability has been verified on a statistical and analytical level. Optimization techniques can be divided into categories as statistical, nature inspired and artificial neural network each with its own benefits and usage in particular cases. A brief introduction about subcategories of different techniques that are available and their computational effectivity will be discussed. The main focus of the study revolves around the applicability of these techniques to any particular operation such as submerged fermentation (SmF) and solid state fermentation (SSF), their ability to produce secondary metabolites and the usefulness in the laboratory and industrial level. Primary studies to determine the enzyme activity of different microorganisms such as bacteria, fungi and yeast will also be discussed. l-Asparaginase, the most commonly used drugs in the treatment of acute lymphoblastic leukemia (ALL) shall be considered as an example, a short discussion on models used in the production by the processes of SmF and SSF will be discussed to understand the optimization techniques that are being dealt. It is expected that this discussion would help in determining the proper technique that can be used in running any optimization process for different purposes, and would help in making these processes less time-consuming with better output.

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 N^α -(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.

Pharmacodynamic effects in the cerebrospinal fluid of rats after intravenous administration of different asparaginase formulations

PURPOSE

Asparaginase (ASNase) is used to treat various hematological malignancies for its capacity to deplete asparagine (ASN) in serum and cerebrospinal fluid (CSF). Since the biological mechanisms underlying CSF asparagine depletion in humans are not yet fully elucidated, this study compared, for the first time, the pharmacological properties of three clinically used ASNase formulations in a rodent model.

METHODS

Male Wistar rats were treated with E.coli-ASNase, PEG-ASNase, or ERW-ASNase at different doses. Serum and CSF amino-acid levels and ASNase activities were evaluated at 1 and 24 h after the intravenous administration of different ASNase doses.

RESULTS

All the ASNase formulations showed higher activities in serum after 1 h than 24 h and completely deplete ASN. Mean ASNase activity in the CSF at 1 h was higher with ERW-ASNase compared to PEG-ASNase (36 ± 29 vs 8 ± 7 U/L, p < 0.037) and similar to E.coli-ASNase (21 ± 9 U/L, ns). ERW-ASNase and E.coli-ASNase at the highest doses were able to deplete ASN in the CSF after 1 h. This effect was transient and not evident at 24 h after treatment.

CONCLUSIONS

Together with the ASN depletion in serum and CSF, a never before demonstrated transient penetration of ASNases into the CSF, more evident for non-pegylated formulations, was detected when the ASNases were administered at high dose.

Antithrombin III as the Indicator of L-Asparaginase Activity in Children Treated for Acute Lymphoblastic Leukemia

L-asparaginase (ASP) is widely used in the treatment of acute lymphoblastic leukemia (ALL) in children. Monitoring its activity is necessary because of the risk of drug inactivation as the result of an immune reaction. Besides allergic reactions, another frequent side effect of ASP treatment is coagulopathy, especially deficiency of antithrombin III (ATIII). The aim of this study was to analyze the relationship between ASP and ATIII activities and the possibility of ATIII activity use in an indirect ASP activity assessment. ASP and ATIII activity was measured in 76 children with ALL treated according to the ALL IC BFM 2002 protocol. A correlation between ASP and ATIII activities was found (R=-0.43, P=0.0001). ROC curve analysis revealed some utility regarding the determination of ATIII in identifying patients with low or undetectable ASP activity (area under the curve=0.87 [95% confidence interval, 0.77-0.96], P<0.0001 and 0.93 [95% confidence interval, 0.85-1.0], P<0.0001, respectively). Higher ATIII activity is associated with a higher probability of a decline in ASP activity. Examination of ATIII activity cannot replace a direct determination of ASP activity, but in the case of unavailability of the direct test, it can be a helpful surrogate parameter of drug activity.

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.

Population pharmacokinetics of intravenous Erwinia asparaginase in pediatric acute lymphoblastic leukemia patients

Erwinia asparaginase is an important component in the treatment of pediatric acute lymphoblastic leukemia. A large variability in serum concentrations has been observed after intravenous Erwinia asparaginase. Currently, Dutch Childhood Oncology Group protocols dose alterations are based on trough concentrations to ensure adequate asparaginase activity (≥100 IU/L). The aim of this study was to describe the population pharmacokinetics of intravenous Erwinia asparaginase to quantify and gather insight into inter-individual and inter-occasion variability. The starting dose was evaluated on the basis of the derived population pharmacokinetic parameters. In a multicenter prospective observational study, a total of 714 blood samples were collected from 51 children (age 1–17 years) with acute lymphoblastic leukemia. The starting dose was 20,000 IU/m² three times a week and adjusted according to trough levels from week three onwards. A population pharmacokinetic model was developed using NONMEM^®. A 2-compartment linear model with allometric scaling best described the data. Inter-individual and inter-occasion variability of clearance were 33% and 13%, respectively. Clearance in the first month of treatment was 14% higher (P<0.01). Monte Carlo simulations with our pharmacokinetic model demonstrated that patients with a low weight might require higher doses to achieve similar concentrations compared to patients with high weight. The current starting dose of 20,000 IU/m² might result in inadequate concentrations, especially for smaller, lower weight patients, hence dose adjustments based on individual clearance are recommended. The protocols were approved by the institutional review boards. (Registered at NTR 3379 Dutch Trial Register; www.trialregister.nl).

L-asparaginase in the treatment of patients with acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a hematologic malignancy that predominantly occurs in children between 2 and 10 years of age. L-asparaginase is an integral component of treatment for patients with ALL and since its introduction into pediatric treatment protocols in the 1960s, survival rates in children have progressively risen to nearly 90%. Outcomes for adolescent and young adult (AYA) patients, aged 15-39 years and diagnosed with ALL, have historically been less favorable. However, recent reports suggest substantially increased survival in AYA patients treated on pediatric-inspired protocols that include a greater cumulative dose of asparaginase. All  currently available asparaginases share the same mechanism of action - the deamination and depletion of serum asparagine levels - yet each displays a markedly different pharmacokinetic profile. Pegylated asparaginase derived from the bacterium Escherichia coli is used as first-line therapy; however, up to 30% of patients develop a treatment-limiting hypersensitivity reaction. Patients who experience a hypersensitivity reaction to an E. coli-derived asparaginase can continue treatment with Erwinia chrysanthemi asparaginase. Erwinia asparaginase is immunologically distinct from E. coli-derived asparaginases and exhibits no cross-reactivity. Studies have shown that with adequate dosing, therapeutic levels of Erwinia asparaginase activity can be achieved, and patients switched to Erwinia asparaginase due to hypersensitivity can obtain outcomes similar to patients who do not experience a hypersensitivity reaction. Therapeutic drug monitoring may be required to ensure that therapeutic levels of asparaginase activity are maintained.

Erythrocyte encapsulated l-asparaginase (GRASPA) in acute leukemia

l-asparaginase, an enzyme originally derived from Escherichia coli, represents a major drug in the treatment of acute lymphoblastic leukemia. However, the occurrence of major adverse effects often leads to early withdrawal of the enzyme. Main side effects include immune-allergic reactions, coagulopathy, pancreatitis and hepatic disorders. Novel asparaginase formulations and alternative sources have been developed to address this issue, but the results were not totally satisfactory. l-asparaginase loaded red blood cells (RBCs; GRASPA) represent a new asparaginase presentation with reduced immunological adverse reactions. RBCs protect l-asparaginase, enhance its half-life and reduce the occurrence of adverse events. We reviewed the history, biology and clinical experiences with l-asparaginase, and the characteristics and first clinical experiences with GRASPA in the treatment of acute leukemia.

Asparaginase Erwinia chrysanthemi as a component of a multi-agent chemotherapeutic regimen for the treatment of patients with acute lymphoblastic leukemia who have developed hypersensitivity to E. coli-derived asparaginase

Asparaginase has been a mainstay of therapy in the treatment of acute lymphoblastic leukemia since the 1970s. There are two major preparations available and FDA approved in the United States today, one derived from Escherichia coli and the other from Erwinia chrysanthemi. Erwinia asparaginase is antigenically distinct from and has a considerably shorter biological half-life than E coli asparaginase. Erwinia asparaginase has been used in cases of hypersensitivity to E. coli-derived asparaginases, which has been reported in up to 30% of patients. While PEG asparaginase is increasingly used in front-line therapy for ALL, hypersensitivity still occurs with this preparation, and a change to a non-cross-reactive preparation may be necessary.

L-asparaginase as a critical component to combat Acute Lymphoblastic Leukaemia (ALL): A novel approach to target ALL

L-asparaginase, an anti-leukaemic drug that has been approved for clinical use for many years in the treatment of childhood Acute Lymphoblastic Leukaemia (ALL), is obtained from bacterial origin (Escherichia coli and Erwinia carotovora). The efficacy of L-asparaginase has been discussed for the past 40 years, and an ideal substitute for the enzyme has not yet been developed. The early clearance from plasma (short half-life) and requirement for multiple administrations and hence frequent physician visits make the overall treatment cost quite high. In addition, a high rate of allergic reactions in patients receiving treatment with the enzyme isolated from bacterial sources make its clinical application challenging. For these reasons, various attempts are being made to overcome these barriers. Therefore, the present article reviews studies focused on seeking substitutes for L-asparaginase through alternative sources including bacteria, fungi, actinomycetes, algae and plants to overcome these limitations. In addition, the role of chemical modifications and protein engineering approaches to enhance the drug's efficacy are also discussed. Moreover, an overview has also been provided in the current review regarding the contradiction among various researchers regarding the significance of the enzyme's glutaminase activity.

Asparaginase in acute lymphoblastic leukemia

Cure rates in pediatric acute lymphoblastic leukemia have significantly improved over the past decades. Now, almost 90% of children will survive the disease. The cure rates in adolescents, young adults, and adults have not kept pace with the improvements in younger patients, even though almost an equal proportion of adult patients achieve complete remission as their pediatric counterparts. Differences in treatment regimens might be important. Intensive use of asparaginase has been a key component of successful pediatric therapy. In this review, we focus on the use of asparaginase and the potential of optimizing asparaginase use via monitoring to minimize adverse drug events and improve efficacy of the drug.

Allergic Reactions Associated with Intravenous Versus Intramuscular Pegaspargase: A Retrospective Chart Review

BACKGROUND

Pegaspargase (PEG-ASP) is essential chemotherapy for acute lymphoblastic leukemia (ALL). Since changing to intravenous (IV) administration from intramuscular (IM), an increased number of allergic reactions have been anecdotally noted at our institution. This study compares the rate and severity of allergic reactions in children receiving IM or IV PEG-ASP.

METHODS

We performed a retrospective chart review of patients treated with IV or IM PEG-ASP at The Hospital for Sick Children, Toronto, Canada, from March 1, 2010 to January 1, 2012. The incidence and severity of allergic reactions attributed to PEG-ASP were documented. Patient age, sex, route of PEG-ASP administration, disease (risk group and lineage) and mean time interval between PEG-ASP doses were evaluated as possible risk factors for allergic reaction.

RESULTS

A total of 109 patients were included. There were 14 (35 %) allergic reactions among 40 patients who received IV, compared with eight (12 %) of the 69 who received IM [odds ratio (OR) 4.11, 95 % confidence interval (CI) 1.54-10.97, p = 0.005]. In multivariable logistic regression adjusting for disease risk group, route (IV vs. IM) remained independently significant (p = 0.011). Patients with standard-risk ALL had a lower risk of experiencing an allergic reaction associated with PEG-ASP compared with patients in high-risk disease risk groups (collectively referred to as "other"; 11 vs. 31 %, OR 3.36, 95 % CI 1.16-9.72, p = 0.025).

CONCLUSIONS

IV PEG-ASP is associated with a significantly higher rate of allergic reactions than IM. The clinical preference for IV PEG-ASP may warrant re-evaluation.

Clinical application of asparaginase activity levels following treatment with pegaspargase

Asparaginase, an enzyme used to treat acute lymphoblastic leukemia and related forms of nonHodgkin lymphoma, depletes asparagine, which leads to lymphoblast cell death. Unlike most chemotherapeutic agents, asparaginase is a foreign protein that can result in clinical allergy and/or silent hypersensitivity with production of neutralizing antibodies that inactivate asparaginase. In North America, asparaginase activity levels can now be obtained via a commercially available assay, for therapeutic drug monitoring and investigation of potential allergic reactions. Herein, we provide recommendations and a corresponding algorithm for the clinical application of this assay after treatment with pegaspargase to evaluate suspected hypersensitivity reactions and/or silent inactivation.