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

Phase 2 multicenter study of pegaspargase in Japanese patients with previously untreated acute lymphoblastic leukemia

Pegaspargase is a pegylated formulation of E. coli-derived asparaginase, which when combined with multi-agent chemotherapy is an effective, well-established therapy for acute lymphoblastic leukemia (ALL). This study evaluated the efficacy, safety and pharmacokinetics of lyophilized pegaspargase in the Japanese population. The study had two parts; the primary endpoint for Part 1 was the incidence and nature of treatment-emergent adverse events (TEAEs), including those related to pegaspargase, to determine the number of patients who experience intolerable toxicity during a tolerability assessment period. The primary endpoint for Part 2 was the percentage of patients with plasma asparaginase activity of ≥ 0.1 IU/ml 14 days after administration of the first dose of lyophilized pegaspargase. All 26 patients included in the safety analysis experienced at least one TEAE. Frequently reported TEAEs related to lyophilized pegaspargase included decreases in blood fibrinogen, antithrombin III, white blood cell count, and platelet count. No deaths were reported. Plasma asparaginase activity reached ≥ 0.1 IU/ml 5 min after the first dose of lyophilized pegaspargase and was maintained for 14 days in all patients with evaluable samples. The results of this study show that lyophilized pegaspargase represents an effective and well-tolerated first-line treatment option in Japanese patients with ALL.

pH-Sensitive blue and red N-CDs for L-asparaginase quantification in complex biological matrices

A novel fluorometric method for the determination of L-asparaginase, an enzyme crucial in cancer therapy and food industry applications, is presented. This sensitive and selective approach utilizes L-asparagine and two pH-sensitive carbon dots (blue-N-CDs and red-N-CDs) as probes. The interaction between L-asparagine and L-asparaginase liberates ammonia, causing an increase in pH. This pH change simultaneously decreases the fluorescence of blue-N-CDs while enhancing the emission of red-N-CDs, enabling ratiometric detection of L-asparaginase. Comprehensive characterization of both carbon dots and investigation of their response mechanism towards L-asparaginase were conducted using ultraviolet-visible spectrophotometry, fluorescence spectroscopy, and transmission electron microscopy (TEM) imaging techniques. The designed approach demonstrates outstanding linearity (20 to 2000 U L-1) and a low detection limit (6.95 U L-1) for L-asparaginase quantification. Moreover, when tested to human serum samples, the detection system exhibits outstanding selectivity and high recovery rates (96.15% to 99.75%) with low standard deviation, underscoring its suitability for practical implementation in clinical diagnostics.

Recombinant Erwinia asparaginase (JZP458) in ALL/LBL: complete follow-up of the Children's Oncology Group AALL1931 study

ABSTRACT

Children's Oncology Group study AALL1931 investigated the efficacy and safety of recombinant Erwinia asparaginase (JZP458) in patients with acute lymphoblastic leukemia/lymphoblastic lymphoma and hypersensitivity reactions/silent inactivation to Escherichia coli-derived asparaginases. Each pegylated Escherichia coli asparaginase dose remaining in a patient's treatment plan was replaced by intramuscular (IM) or IV JZP458 (6 doses) administered Monday/Wednesday/Friday (MWF). Three IM cohorts (1a [25 mg/m2 MWF], n = 33; 1b [37.5 mg/m2 MWF], n = 83; 1c [25/25/50 mg/m2 MWF], n = 51) and 1 IV cohort (25/25/50 mg/m2 MWF, n = 62) were evaluated. The proportion (95% confidence interval [CI]) of patients maintaining nadir serum asparaginase activity (NSAA) levels of ≥0.1 IU/mL at the last 72 (primary end point) and 48 hours during course 1 was 90% (95% CI, 81-98) and 96% (95% CI, 90-100) in IM cohort 1c, respectively, and 40% (95% CI, 26-54) and 90% (95% CI, 82-98) in the IV cohort. Population pharmacokinetic modeling results were comparable with observed data, predicting the vast majority of patients would maintain therapeutic NSAA levels when JZP458 is administered IM or IV 25 mg/m2 every 48 hours, or IM 25/25/50 mg/m2 MWF, or with mixed IM and IV administration (IV/IV/IM 25/25/50 mg/m2 MWF). Drug discontinuation occurred in 23% and 56% of patients in the IM and IV cohorts, respectively; 13% and 33% because of treatment-related adverse events (mainly allergic reactions and pancreatitis). JZP458 achieves therapeutic NSAA levels via multiple IM and IV dosing schedules based on combined observed and modeled data with a safety profile consistent with other asparaginases. This trial was registered at www.ClinicalTrials.gov as #NCT04145531.

Outcome of 421 adult patients with Philadelphia-negative acute lymphoblastic leukemia treated under an intensive program inspired by the GIMEMA LAL1913 clinical trial: a Campus ALL study

The introduction of pediatric-inspired regimens in adult Philadelphia-negative acute lymphoblastic leukemia (Ph- ALL) has significantly improved patients' prognosis. Within the Campus ALL network, we analyzed the outcome of adult Ph- ALL patients treated according to the GIMEMA LAL1913 protocol outside the clinical trial to compare the real-life data with the study results. We included 421 consecutive patients; median age 42 years. The complete remission (CR) rate after the first course of chemotherapy was 94%, and measurable residual disease (MRD) negativity after the third course was achieved in 72% of patients. The 3-year overall survival (OS) and disease-free survival (DFS) were 67% and 57%, respectively. In a multivariate analysis, MRD positivity negatively influenced DFS. In a time-dependent analysis including only very high-risk (VHR) and MRD positive cases, transplanted (hematopoietic stem cell transplantation [HSCT]) patients had a significantly better DFS than non-HSCT patients (P=0.0017). During induction, grade ≥2 pegaspargase-related hepato-toxicity was observed in 25% of patients (vs. 12% in the GIMEMA LAL1913 trial, P=0.0003). In this large, real-life cohort of Ph- ALL, we confirmed the very high CR rate and a superimposable OS and DFS compared to the GIMEMA LAL1913 clinical trial (CR rate after C1, 94% vs. 85%, P=0.0004; 3-year OS, 67% vs. 67%, P=0.94; 3-year DFS, 57% vs. 63%, P=0.17). HSCT confirms its important role in VHR and MRD-positive patients. The rate of pegaspargase-related toxicity was significantly higher in the real-life setting, emphasizing the importance of dose adjustment in the presence of risk factors to avoid excessive toxicity.

Improved HPLC method with automated pre-column sample derivatisation for serum pegylated L-asparaginase activity measurement in paediatric acute lymphoblastic leukaemia patients

Therapeutic drug monitoring of pegylated L-asparaginase (ASNase) ensures the drug effectiveness in childhood acute lymphoblastic leukaemia (ALL) patients. The biological drug property with variable immunogenic host clearance, and the prescription of its generic formulation urge the need for a reliable assay to ensure an optimal treatment and improve outcome. This study aimed to optimise an existing isocratic reversed-phase high performance liquid chromatography (RP-HPLC) method with an automated pre-column sample derivatisation and injection program, and a computational algorithm for measuring serum pegylated ASNase activity in children with ALL. Nath et al.'s method in 2009 was adopted and modified using a pegylated ASNase. A set of Microsoft Excel macros was developed for the serum drug activity computation. An Agilent InfinityLab LC Series 1260 Infinity II Quaternary System with fluorescence detection was employed with an Agilent Poroshell 120 EC-C18 4.6×100 mm, 2.7 µm analytical column. System flow rate was optimised to 2.0 mL/min with 40×10-6/bar pump compressibility. The O-phthaldialdehyde (OPA) solution composition was optimised to 1 % o-phthaldialdehyde, 0.8 % 2-mercaptoethanol, 7.13 % methanol, and 1.81 % sodium tetraborate. The pre-column derivatisation program mixed 0.1 µL sample with 25 µL OPA solution before the automated injection. Method validation was according to the ICH guidelines. Total analysis time was 15 min, with L-aspartic acid eluted at 0.96 min and internal standard at 4.7 min. The calibration curves showed excellent linearity (R ≥0.9999). Interday precision for the drug activity at 0.1 IU/mL, 0.5 IU/mL, and 1 IU/mL were 4.15 %, 3.05 %, and 3.09 % (n = 6). Mean %error for the drug activity at 0.1 IU/mL, 0.5 IU/mL, and 1 IU/mL were 0.90±4.41 %, -1.37±3.04 %, and -3.03±3.02 % (n = 6). Limit of quantitation was 0.03 IU/mL. Majority of the patients' serum drug activity fell within the assay calibration range. Our improved method is automated, having shorter analysis time with a well-maintained separation resolution that enables a high-throughput analysis for application.

Insights into Asparaginase Allergic Responses: Exploring Pharmacogenetic Influences

Acute lymphoblastic leukemia represents the most prevalent childhood cancer. Modern chemotherapy has significantly improved outcomes, achieving EFS rates of 80% and OS rates nearing 90% in developed nations, while in developing regions, rates remain below 50%, highlighting disparities, and this difference is due to several factors. Genetic variability plays a role in these drug response disparities, presenting single-nucleotide variations (SNVs). Pharmacogenetic research aims to pinpoint these SNVs early in treatment to predict specific drug responses effectively. This review aims to explore advancements in pharmacogenetics associated with asparaginase (ASNase). ASNase plays a crucial role in the treatment of ALL and is available in three formulations: E. coli, Erwinia, and PEG ASNase. ASNase therapy presents challenges due to adverse effects, like hypersensitivity reactions. Identifying predictive markers for hypersensitivity development beforehand is crucial for optimizing treatments. Several pharmacogenetic studies have investigated the association between SNVs and the risk of hypersensitivity. Key genes include GRIA1, NFATC2, CNTO3, ARHGAP28, MYBBP1A, and HLA. Studies have highlighted associations between SNVs within these genes and hypersensitivity reactions. Notably, most pharmacogenetic investigations of hypersensitivity have focused on patients treated with E. coli, emphasizing the need for broader exploration across different formulations. Future research investigating these variants holds promise for advancing our understanding of ASNase's pharmacogenetics.

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.

Evaluating the efficacy and toxicity of dose adjusted pegylated L-asparaginase in combination with therapeutic drug monitoring

The incorporation of pediatric-inspired regimens in the adolescent-young-adult (AYA) and adult populations have resulted improved survival outcomes (Stock et al. Blood 133(14):1548-1559 2019; Dunsmore et al. J Clin Oncol 38(28):3282-3293 2020; DeAngelo et al. Leukemia 29(3):526-534 2015). Nonetheless incorporation of such regimens is limited by increased toxicity to asparaginase. Dosing strategies that reduce the weight-based dose of pegylated-L-asparaginase (PEG-asparaginase) utilizing activity monitoring have been shown to result in better tolerability of these regimens. The purpose of this study was to analyze the efficacy and safety of treating adults with Philadelphia chromosome negative (Ph-) ALL with pediatric-inspired regimens that incorporate PEG-asparaginase dose adjustments and asparaginase activity level monitoring. Patients aged 18-65 years initiated on pediatric-inspired regimens utilizing dose-reduced PEG-asparaginase with therapeutic drug monitoring-guided adjustments were included. The screening of 122 patients treated between 2015 and 2021 resulted in the inclusion of 54 patients. The median age of the cohort was 35 years (16-65 years), and median body mass index (BMI) was 30 kg/m2 (18.3-53.4 kg/m2). The 36-month survival estimate was 62.1% (95% CI 48.1-77.7%), and the median overall survival (OS) was 62.2 months (95% CI 35.1-89.3 months). In the AYA cohort, the 36-month survival was 71.2% (95% CI 55.8-91%) and the median overall survival was not reached. Survival was not significantly affected by immunophenotype or BMI. Discontinuation due to toxicity or hypersensitivity reactions was low at 11% and 9% respectively. The encouraging survival outcomes and favorable tolerability of this older population in the real-world setting support the use of individualized PEG-asparaginase dosing with PharmD-guided therapeutic drug monitoring.

Pegaspargase-modified risk-oriented program for adult acute lymphoblastic leukemia: results of the GIMEMA LAL1913 trial

Pediatric-inspired chemotherapy is the standard of care for younger adults with Philadelphia chromosome-negative acute lymphoblastic leukemia/lymphoma (Ph- ALL/LL). In LAL1913 trial, the Gruppo Italiano Malattie EMatologiche dell'Adulto added pegaspargase 2000 IU/m2 to courses 1, 2, 5, and 6 of an 8-block protocol for patients aged from 18 to 65 years, with dose reductions in patients aged >55 years. Responders were risk stratified for allogeneic hematopoietic cell transplantation (HCT) or maintenance per clinical characteristics and minimal residual disease (MRD). Of 203 study patients (median age, 39.8 years), 91% achieved a complete remission. The 3-year overall survival, event-free, and disease-free survival (DFS) rates were 66.7%, 57.7%, and 63.3%, respectively, fulfilling the primary study end point of a 2-year DFS >55%. Although based on the intention-to-treat, the DFS being 74% and 50% in the chemotherapy (n = 94) and HCT (n = 91) assignment cohorts, respectively, a time-dependent analysis proved the value of HCT in patients who were eligible (DFS HCT 70% vs no HCT 26%; P <.0001). In multivariate analysis, age and MRD were independent factors predicting DFS rates of 86% (age ≤ 40 and MRD-negative), 64%-65% (MRD-positive or age > 40) and 25% (age > 40 and MRD-positive); P < .0001. Grade ≥2 pegaspargase toxicity was mainly observed at course 1, contributing to induction death in 2 patients but was rare thereafter. This program improved outcomes of patients with Ph- ALL/LL aged up to 65 years in a multicenter national setting. This trial was registered at www.clinicaltrials.gov as #NCT02067143.

Asparaginase therapy in patients with acute lymphoblastic leukemia: expert opinion on use and toxicity management

The addition of asparaginase to acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) treatment regimens provides significant patient benefits. Asparaginase therapies vary in origin (Escherichia coli- or Erwinia-derived) and preparation (native or pegylated), conferring distinct pharmacokinetic and immunogenic profiles. Clinical hypersensitivity reactions (HSRs) are commonly reported in patients and range from localized erythema to systemic anaphylaxis. Due to its favorable pharmacokinetic profile and reduced immunogenicity compared to native E. coli preparations, pegaspargase is the first-line asparaginase therapeutic option. Switching to an Erwinia-derived asparaginase is recommended for patients who experience HSRs or antibody-mediated inactivation to achieve the significant clinical benefit observed in patients who complete asparaginase treatment. Previous global shortages of asparaginase Erwinia chrysanthemi necessitated conversion mitigation strategies such as premedication protocols, desensitization, and asparaginase activity level monitoring. Here, we discuss the efficacy, safety, pharmacokinetics, current use, and administration of asparaginase therapies for pediatric and adolescent patients with ALL/LBL.

Follow our path with asparaginase activity: one technique, but different uses in clinical practice

Acute lymphoblastic leukemia is the most common childhood malignancy. One of the drugs used in the treatment is Asparaginase, and monitoring of its activity levels enables better outcomes. Since 2018, our laboratory has been working to establish a regular analysis of activity. This implementation allowed to qualify care by detecting silent inactivation and also establishing desensitization as a safe way to overcome the lack of Erwinia. We were able to monitor children aged 0 to 18 years who were being treated with PEG-ASNase. The activity was assessed on days 7 (90 samples) and 14 (52 samples) after ASNase infusions. 142 samples were analyzed. 95.7% reached an adequate activity level (≥ 0.1 IU/mL). Patients treated with ASNase can develop allergic reactions. With the activity monitoring, is possible to circumvent situations like these and implement desensitization protocols for patients who had clinical hypersensitivity without inactivation. Desensitization induces temporary unresponsiveness to drug antigens, allowing the patients to proceed with the prescribed chemotherapy. We have received samples from four patients being treated with different desensitization protocols. Patients tolerated the protocols well. Only one had a grade 2 reaction during the infusion and activity < 0.1 IU/mL, which resulted in the switch to Erwinia. The dose adaptation is a possible and more recent use of ASNase monitoring and we were able to confirm the feasibility of PEG-ASNase desensitization protocols.

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.

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.

Activity and toxicity of intramuscular 1000 iu/m2 polyethylene glycol-E. coli L-asparaginase in the UKALL 2003 and UKALL 2011 clinical trials

In successive UK clinical trials (UKALL 2003, UKALL 2011) for paediatric acute lymphoblastic leukaemia (ALL), polyethylene glycol‐conjugated E. coli L‐asparaginase (PEG‐EcASNase) 1000 iu/m² was administered intramuscularly with risk‐stratified treatment. In induction, patients received two PEG‐EcASNase doses, 14 days apart. Post‐induction, non‐high‐risk patients (Regimens A, B) received 1–2 doses in delayed intensification (DI) while high‐risk Regimen C patients received 6–10 PEG‐EcASNase doses, including two in DI. Trial substudies monitored asparaginase (ASNase) activity, ASNase‐related toxicity and ASNase‐associated antibodies (total, 1112 patients). Median (interquartile range) trough plasma ASNase activity (14 ± 2 days post dose) following first and second induction doses and first DI dose was respectively 217 iu/l (144–307 iu/l), 265 iu/l (165–401 iu/l) and 292 iu/l (194–386 iu/l); 15% (138/910) samples showed subthreshold ASNase activity (<100 iu/l) at any trough time point. Older age was associated with lower (regression coefficient −9.5; p < 0.0001) and DI time point with higher ASNase activity (regression coefficient 29.9; p < 0.0001). Clinical hypersensitivity was observed in 3.8% (UKALL 2003) and 6% (UKALL 2011) of patients, and in 90% or more in Regimen C. A 7% (10/149) silent inactivation rate was observed in UKALL 2003. PEG‐EcASNase schedule in UKALL paediatric trials is associated with low toxicity but wide interpatient variability. Therapeutic drug monitoring potentially permits optimisation through individualised asparaginase dosing.

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.

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.

Premedication prior to PEG-asparaginase is cost-effective in pediatric patients with acute lymphoblastic leukemia

BACKGROUND

PEG-asparaginase is critical in pediatric acute lymphoblastic leukemia (ALL) therapy but is highly immunogenic. Severe allergic reactions lead to substitution of further PEG-asparaginase with Erwinia. Erwinia is associated with more frequent dosing, increased expense, and limited availability. Premedication may reduce rates of allergic reactions.

PROCEDURES

This Markov model evaluated the cost-effectiveness of three strategies: premedication plus therapeutic drug monitoring (TDM), TDM alone, and no premedication or TDM. We modeled two scenarios: a standard-risk (SR) B-ALL patient receiving two asparaginase doses and a high-risk (HR) patient receiving seven asparaginase doses. The model incorporated costs of asparaginase, premedication, TDM and clinic visits, and lost parental wages associated with each additional Erwinia dose. We incorporated a five-year time horizon with a societal perspective. Outcomes were Erwinia substitutions avoided and differences in quality-adjusted life years (QALYs). Probabilistic and one-way sensitivity analyses evaluated model uncertainty.

RESULTS

In both scenarios, premedication was the least costly strategy. In SR and HR scenarios, premedication with monitoring resulted in 8% and 7% fewer changes to Erwinia compared with monitoring alone and 3% and 2% fewer changes compared with no premedication/monitoring, respectively. Premedication resulted in the most QALYs gained in the SR patients. Individual variation of model inputs did not change premedication/monitoring favorability for either scenario. In probabilistic sensitivity analyses, premedication/monitoring was favored in >87% of iterations in both scenarios.

CONCLUSION

Compared with other strategies, premedication use and asparaginase level monitoring in children with B-ALL is potentially cost-saving.

Clinical Utility of Pegaspargase in Children, Adolescents and Young Adult Patients with Acute Lymphoblastic Leukemia: A Review

Acute lymphoblastic leukemia (ALL) is a heterogenous hematological malignancy representing 25% of all cancers in children less than 15 years of age. Significant improvements in survival and cure rates have been made over the past four decades in pediatric ALL treatment. Asparaginases, derived from Escherichia coli and Erwinia chrysanthemi, have become a critical component of ALL therapy since the 1960s. Asparaginases cause depletion of serum asparagine, leading to deprivation of this critical amino acid for protein synthesis, and hence limit survival of lymphoblasts. Pegaspargase, a conjugate of monomethoxypolyethylene glycol (mPEG) and L-asparaginase, has become an integral component of pediatric upfront and relapsed ALL protocols due to its longer half-life and improved immunogenicity profile compared to native asparaginase preparations. Over the past two decades great strides have been made in outcomes for pediatric ALL due to risk stratification, incorporation of multiagent chemotherapy protocols, and central nervous system prophylaxis with pegaspargase having played an important role in this success. However, adolescents and young adults (AYA) with ALL when treated on contemporaneous trials using adult ALL regimens, continue to have poor outcomes. There is increasing realization of adapting pediatric trial regimens for treating AYAs, especially those incorporating higher intensity of chemotherapeutic agents with pegaspargase being one such agent. Dose or treatment-limiting toxicity is observed in 25-30% of patients, most notable being hypersensitivity reactions. Other toxicities include asparaginase-associated pancreatitis, thrombosis, liver dysfunction, osteonecrosis, and dyslipidemia. Discontinuation or subtherapeutic levels of asparaginase are associated with inferior disease-free survival leading to higher risk of relapse, and in cases of relapse, a higher risk for remission failure. This article provides an overview of available evidence for use of pegaspargase in pediatric acute lymphoblastic leukemia.

National Italian Delphi panel consensus: which measures are indicated to minimize pegylated-asparaginase associated toxicity during treatment of adult acute lymphoblastic leukemia?

BACKGROUND

L-asparaginase (L-ASP) is a key component of acute lymphoblastic leukemia (ALL) treatment, but its use in clinical practice raises challenges to clinicians due to a relatively high incidence of drug-related adverse events, mainly in adult patients. In the past years the use of ASP in adult population has been mainly limited due to a poor knowledge of its safety profile and to an approximate management of ASP-related toxicity. Recently the development of pediatric-inspired treatment protocols for adult ALL has led to a wider use of ASP and since 2010 in Italy three national treatment protocols including Pegylated asparaginase (Peg-ASP) have been sequentially developed for adolescents, young adults and adults with Philadelphia-negative (Ph-) ALL.

METHODS

With the aim to better understand the approach adopted in Italian centers for the management and prevention of Peg-ASP toxicity in adult ALL and to provide practical, consensus-based recommendations, a board of 6 Italian clinicians, with known expertise in adult ALL, designed 41 consensus statements on current challenges on the management of Peg-ASP associated toxicity. A group of 19 clinical experts in the field then rated these statements using the 5-point Likert-type scale (1 = strongly disagree; 5 = strongly agree).

RESULTS

The main Peg-ASP related issues identified by the board included: 1) clinician's attitudes; 2) toxicity profile; 3) hypersensitivity reactions; 4) hepatic toxicity; 5) hepatic and/or metabolic toxicity; 6) hemorrhagic/thrombotic toxicity; 7) pancreatitis; 8) metabolic toxicity management and prevention; 9) activity levels monitoring. Overall, participants agreed on most statements, except those addressing the potential contraindications to the treatment with Peg-ASP, such as patients with a diagnosis of chronic liver disease or the subsequent administrations of the drug in patients who had previously developed chemical pancreatitis or severe metabolic toxicity. Participants agreed that adult patients with ALL should receive Peg-Asp because this drug is essential to improve treatment results.

CONCLUSIONS

The panel agreed that a critical evaluation of specific risk factors for each patient is crucial in order to reduce the risk of adverse events and specific advices in the management of Peg-ASP toxicities are reported.

Efficacy and toxicity of reduced vs. standard dose pegylated asparaginase in adults with Philadelphia chromosome-negative acute lymphoblastic leukemia

Incorporation of asparaginase (ASNase) and pegylated asparaginase (PEG-ASP) into pediatric-inspired regimens for adults with acute lymphoblastic leukemia (ALL) has led to improved treatment outcomes albeit with increased toxicities. This study compared the efficacy and safety of the Children's Oncology Group standard PEG-ASP (SD) dosing (>1000, median 2500 IU/m2/dose) in adult Philadelphia chromosome-negative ALL patients receiving multiagent chemotherapy vs reduced dose PEG-ASP (RED) (≤1000, median 500 IU/m2/dose) during induction. 51 patients were included, 26 in RED and 25 in SD (median age 49 vs 37 years, p = .027). Median day 7 ASNase activity level for RED was 0.16 IU/mL. All 11 patients who received PEG-ASP 1000 IU/m2 and 9/11 patients who received 500 IU/m2 achieved an ASNase level ≥0.1 IU/mL. Patients receiving RED experienced fewer total grade 3/4 toxicities during induction compared to SD (p = .02) while still attaining therapeutic ASNase levels. RED permits safer ASNase use in adults with ALL and should be tested in a larger cohort prospectively.

Retrospective cohort study monitoring PEG-asparaginase activity in acute lymphoblastic leukemia patients with and without premedication

Background: PEG-L-asparaginase (pegaspargase) is a critical component of therapy for children and adults with acute lymphoblastic leukemia (ALL). Allergic reactions, which may occur in up to one third of patients, are the major cause for discontinuation. One study reported lower rates of allergic reactions with premedication. Besides allergy, an unknown number of patients develop silent neutralizing antibodies not associated with allergic reactions. The purpose of this retrospective cohort study was to determine the incidence of silent inactivation of pegasparaginase and compare incidence of allergic reactions with and without premedication.

Methods: Using a commercial assay, asparaginase activity was monitored following pegaspargase (2500 units/m ) in newly diagnosed children and young adults with B- and T-cell ALL from February 2013 to May 2017. The incidence of allergic reactions before and after initiation of premedication in May 2015 was compared.

Results: One patient out of 59 (1.7%) had silent inactivation after the second dose. No patient had silent inactivation after the first pegaspargase dose and no standard risk B-cell ALL patients, who received only two pegaspargase doses in combination with oral dexamethasone, had silent inactivation. The incidence of grade 3 or 4 allergic reactions was 3.7% per dose with premedication (methylprednisolone, acetaminophen and diphenhydramine) versus 5.2% without. The incidence per patient with premedication given for most of the doses was 8.3% versus 17% without. These values are not statistically significant. Premedication did not affect pegaspargase activity.

Conclusions: Due to the low incidence of silent inactivation with intravenous pegaspargase and the unlikely event patients receiving only two doses of pegasparaginase would receive erwinase for this possible transient silent inactivation, we recommend routine monitoring of pegaspargase activity only in patients scheduled to receive more than two doses.

Practical guidance for the management of acute lymphoblastic leukemia in the adolescent and young adult population

The outstanding therapeutic progress achieved with modern pediatric regimens in childhood acute lymphoblastic leukemia (ALL) led efforts to explore whether a similar treatment approach could be equally effective and safe in older patients, starting initially with older adolescents and young adults (AYA), variably defined in different studies by an age between 15–18 and 25–39 years. Several comparative and noncomparative trials of this type have been carried out during the last two decades, enrolling thousands of patients. Almost without exception, the new strategy improved patients’ outcomes compared with traditional adult treatments in B-lineage and T-lineage Philadelphia (Ph) chromosome-negative B-ALL, while the use of tyrosine kinase inhibitors (TKI) led to comparative progress in Ph+ ALL, a former high-risk subset more typically observed in older age groups. At present, highly effective pediatric-based regimens warrant 5-year survival rates of 60–70% in AYA patients. In view of these data, the same approach was progressively extended to older patients, improving the results up to 55 years of age. Issues of treatment compliance and drug-related toxicity have thus far prevented a comparable therapeutic advancement in patients aged >55 years. This critical review updates and summarizes with pertinent examples this global, positive therapeutic change, and examines how to promote further progress with new targeted therapies that include novel immuno-therapeutics and other agents developed against the many molecular dysfunctions detectable in various ALL subsets. Substantial progress is expected to occur soon, bringing AYA survival figures very close to that of children, and also to improve the outcome of ALL at all ages.

Clinical decisions following implementation of asparaginase activity monitoring in pediatric patients with acute lymphoblastic leukemia: Experience from a single-center study

We undertook this retrospective study to describe decisions made following asparaginase activity monitoring implementation at our center. Clinically apparent reactions (CARs) and asparaginase activity monitoring costs were described. Patients with acute lymphoblastic leukemia, aged <18 years who received asparaginase between April 2016 and September 2017, were included. Decisions made following receipt of asparaginase activity results were categorized as continuation, modification, premedication, or discontinuation. We included 129 patients (median age: 5.33 years) receiving 565 asparaginase doses. CARs were observed following 25 asparaginase doses (19/361 [5.3%] pegaspargase). A total of 224 asparaginase activity levels were ordered in 88 patients. Following receipt of 190 asparaginase activity results, asparaginase therapy was continued, modified, or premedicated in 188 (98.9%), 1 (0.005%), and 1 (0.005%) cases, respectively. Inadequate asparaginase activity was observed in three patients receiving Erwinia asparaginase. Asparaginase activity monitoring allowed patients with pegaspargase-associated CAR and adequate activity to continue therapy unchanged and was cost neutral.

Integrative Approaches in Structural Biology: A More Complete Picture from the Combination of Individual Techniques

With the recent technological and computational advancements, structural biology has begun to tackle more and more difficult questions, including complex biochemical pathways and transient interactions among macromolecules. This has demonstrated that, to approach the complexity of biology, one single technique is largely insufficient and unable to yield thorough answers, whereas integrated approaches have been more and more adopted with successful results. Traditional structural techniques (X-ray crystallography and Nuclear Magnetic Resonance (NMR)) and the emerging ones (cryo-electron microscopy (cryo-EM), Small Angle X-ray Scattering (SAXS)), together with molecular modeling, have pros and cons which very nicely complement one another. In this review, three examples of synergistic approaches chosen from our previous research will be revisited. The first shows how the joint use of both solution and solid-state NMR (SSNMR), X-ray crystallography, and cryo-EM is crucial to elucidate the structure of polyethylene glycol (PEG)ylated asparaginase, which would not be obtainable through any of the techniques taken alone. The second deals with the integrated use of NMR, X-ray crystallography, and SAXS in order to elucidate the catalytic mechanism of an enzyme that is based on the flexibility of the enzyme itself. The third one shows how it is possible to put together experimental data from X-ray crystallography and NMR restraints in order to refine a protein model in order to obtain a structure which simultaneously satisfies both experimental datasets and is therefore closer to the ‘real structure’.

Retrospective cohort study monitoring PEG-asparaginase activity in acute lymphoblastic leukemia patients with and without premedication

Background: PEG-L-asparaginase (pegaspargase) is a critical component of therapy for children and adults with acute lymphoblastic leukemia (ALL). Allergic reactions, which may occur in up to one third of patients, are the major cause for discontinuation. One study reported lower rates of allergic reactions with premedication. Besides allergy, an unknown number of patients develop silent neutralizing antibodies not associated with allergic reactions. The purpose of this retrospective cohort study was to determine the incidence of silent inactivation of pegasparaginase and compare incidence of allergic reactions with and without premedication. Methods: Using a commercial assay, asparaginase activity was monitored following pegaspargase (2500 units/m 2) in newly diagnosed children and young adults with B- and T-cell ALL from February 2013 to May 2017. The incidence of allergic reactions before and after initiation of premedication in May 2015 was compared. Results: One patient out of 59 (1.7%) had silent inactivation after the second dose. No patient had silent inactivation after the first pegaspargase dose and no standard risk B-cell ALL patients, who received only two pegaspargase doses in combination with oral dexamethasone, had silent inactivation. The incidence of grade 3 or 4 allergic reactions was 3.7% per dose with premedication (methylprednisolone, acetaminophen and diphenhydramine) versus 5.2% without.  The incidence per patient with premedication given for most of the doses was 8.3% versus 17% without. These values are not statistically significant. Premedication did not affect pegaspargase activity. Conclusions: Due to the low incidence of silent inactivation with intravenous pegaspargase and the unlikely event patients receiving only two doses of pegasparaginase would receive erwinase for this possible transient silent inactivation, we recommend routine monitoring of pegaspargase activity only in patients scheduled to receive more than two doses.

A single-center multidisciplinary approach to managing the global Erwinia asparaginase shortage

The availability of Erwinia Asparaginase has been limited across the world due to manufacturing shortages or for some countries due to the high acquisition cost, putting patients at risk for inferior outcomes. This manuscript provides guidance on how to manage hypersensitivity reactions and utilize therapeutic drug monitoring (TDM) to conserve and limit Erwinia use. The clinical and financial impact of a multidisciplinary committee are also discussed. Faced with a global Erwinia shortage, a multidisciplinary asparaginase allergy committee was created to review all hypersensitivity reactions to asparaginase therapy, staff education was performed on the management of asparaginase hypersensitivity reactions, an institution-wide premedication policy was mandated, and standardized guidelines were created for TDM. This multidisciplinary approach reduced the PEG-asparaginase to Erwinia switch rate from 21% (35 of 163) to 7% (10 of 134) (p = .0035). A multifaceted approach can safely maintain patients on PEG-asparaginase and conserve Erwinia for patients who need it most.