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

Antibodies against polyethylene glycol (PEG) in healthy subjects raise concerns about the efficacy of pegylated drugs. We evaluated the prevalence of antibodies against PEG among patients with acute lymphoblastic leukemia (ALL) prior to and/or immediately after their first dose of pegylated E.coli asparaginase (PEG-ASNase). Serum samples of 701 children, 673 with primary ALL, 28 with relapsed ALL, and 188 adults with primary ALL were analyzed for anti-PEG IgG and IgM. Measurements in 58 healthy infants served as reference to define cut-points for antibody-positive and -negative samples. Anti-PEG antibodies were detected in ALL patients prior the first PEG-ASNase with a prevalence of 13.9% (anti-PEG IgG) and 29.1% (anti-PEG IgM). After administration of PEG-ASNase the prevalence of anti-PEG antibodies decreased to 4.2% for anti-PEG IgG and to 4.5% for anti-PEG IgM. Pre-existing anti-PEG antibodies did not inhibit PEG-ASNase activity but significantly reduced PEGASNase activity levels in a concentration dependent manner. Although pre-existing anti-PEG antibodies did not boost, pre-existing anti-PEG IgG were significantly associated with firstexposure hypersensitivity reactions (CTCAE grade 2) (p.

Pharmacological and clinical monitoring in children with acute lymphoblastic leukemia treated with a biogeneric PEG-l-asparaginase product.

BACKGROUND: l-Asparaginase (ASP) plays a crucial role in the treatment of childhood acute lymphoblastic leukemia (ALL). Currently, different ASP products are available in the market, including both native and pegylated drugs. Several biogeneric Escherichia coli ASP (GEN-ASP) products have been developed in response to shortages and expensiveness of the native E. coli ASP innovator compounds, but some concerns have been raised about their quality. Recently, a number of generic pegylated ASP products (GEN-PEG-ASP) have been marketed to substitute for the innovator product (PEG-ASP). METHODS: Clinical courses and serum asparaginase activity (SAA) levels were monitored in 12 children with ALL, who were treated in our institution with two doses of a GEN-PEG-ASP product, given IV at 2500 IU/m2 during the remission induction phase. Results were compared with those obtained in a reference cohort of 35 patients treated in our institution, who received the innovator PEG-ASP product at same dosage and within the same chemotherapy background. RESULTS: Compared to the reference cohort treated with PEG-ASP, SAA levels were significantly lower in the 12 patients receiving GEN-PEG-ASP (p < .0001); a higher proportion of ASP-associated hypersensitivity reactions (2/12 vs. 0/35; p = .061) and silent inactivation (3/12 vs. 0/35; p = .014) were observed in comparison with the reference cohort. CONCLUSIONS: Our results highlighted different pharmacological profiles and different rates of hypersensitivity reactions and silent inactivation in the GEN-PEG-ASP cohort compared to those treated with the innovator product. Our findings suggest that a rigorous clinical attention and a thorough pharmacological monitoring are advisable in patients treated with GEN-PEG-ASP products.

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

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

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.

Therapeutic Drug Monitoring of Asparaginase Activity-Method Comparison of MAAT and AHA Test Used in the International AIEOP-BFM ALL 2009 Trial.

BACKGROUND: In the international AIEOP-BFM ALL 2009 trial, asparaginase (ASE) activity was monitored after each dose of pegylated Escherichia coli ASE (PEG-ASE). Two methods were used: the aspartic acid ß-hydroxamate (AHA) test and medac asparaginase activity test (MAAT). As the latter method overestimates PEG-ASE activity because it calibrates using E. coli ASE, method comparison was performed using samples from the AIEOP-BFM ALL 2009 trial. METHODS: PEG-ASE activities were determined using MAAT and AHA test in 2 sets of samples (first set: 630 samples and second set: 91 samples). Bland-Altman analysis was performed on ratios between MAAT and AHA tests. The mean difference between both methods, limits of agreement, and 95% confidence intervals were calculated and compared for all samples and samples grouped according to the calibration ranges of the MAAT and the AHA test. RESULTS: PEG-ASE activity determined using the MAAT was significantly higher than when determined using the AHA test (P < 0.001; Wilcoxon signed-rank test). Within the calibration range of the MAAT (30-600 U/L), PEG-ASE activities determined using the MAAT were on average 23% higher than PEG-ASE activities determined using the AHA test. This complies with the mean difference reported in the MAAT manual. With PEG-ASE activities >600 U/L, the discrepancies between MAAT and AHA test increased. Above the calibration range of the MAAT (>600 U/L) and the AHA test (>1000 U/L), a mean difference of 42% was determined. Because more than 70% of samples had PEG-ASE activities >600 U/L and required additional sample dilution, an overall mean difference of 37% was calculated for all samples (37% for the first and 34% for the second set). CONCLUSIONS: Comparison of the MAAT and AHA test for PEG-ASE activity confirmed a mean difference of 23% between MAAT and AHA test for PEG-ASE activities between 30 and 600 U/L. The discrepancy increased in samples with >600 U/L PEG-ASE activity, which will be especially relevant when evaluating high PEG-ASE activities in relation to toxicity, efficacy, and population pharmacokinetics.

Shedding light on the asparaginase galaxy.

In this issue of Blood, Tong et al have reported that therapeutic drug monitoring (TDM) of asparaginase (ASP) activity levels in plasma may be an important tool for the optimization of its therapeutic effects in pediatric acute lymphoblastic leukemia (ALL).

Four Additional Doses of PEG-L-Asparaginase During the Consolidation Phase in the AIEOP-BFM ALL 2009 Protocol Do Not Improve Outcome and Increase Toxicity in High-Risk ALL: Results of a Randomized Study.

PURPOSE: The AIEOP-BFM ALL 2009 protocol included, at the end of the induction phase, a randomized study of patients with high-risk (HR) ALL to investigate if an intensive exposure to pegylated L-asparaginase (PEG-ASNASE, 2,500 IU/sqm once a week × 4) on top of BFM consolidation phase IB allowed us to decrease minimal residual disease (MRD) and improve outcome. PATIENTS AND METHODS: A total of 1,097 patients presented, from June 2010 to February 2017, with one or more of the following HR criteria: KMT2A::AFF1 rearrangement, hypodiploidy, prednisone poor response, poor bone marrow response at day 15 (Flow MRD ≥10%), or no complete remission (CR) at the end of induction. Of them, 809 (85.1%) were randomly assigned to receive (404) or not receive (405) four weekly doses of PEG-ASNASE. RESULTS: By intention to treat (ITT) analysis, there was no significant difference in the proportion of patients with polimerase chain reaction MRD ≥5 × 10-4 at the end of phase IB in the experimental versus control arm (13.9% v 17.0%, P = .25). The 5-year event-free survival (median follow-up 6.3 years) by ITT in the experimental and control arms was 70.4% (2.3) versus 75.0% (2.2; P = .18), and the 5-year overall survival was 81.5% (2.0) versus 84.0% (1.9; P = .25), respectively. The corresponding 5-year cumulative incidence of death in CR was 9.5% (1.5) versus 5.7% (1.2; P = .08), and that of relapse was 17.7% (1.9) versus 17.2% (1.9), respectively (P = .94). Adverse reactions in phase IB occurred in 22.2% and 8.9% of patients in the experimental and control arm, respectively (P < .001). CONCLUSION: Additional PEG-ASNASE in phase IB did not translate into a benefit for decreasing relapse incidence but was associated with higher toxicity. Further improvements with conventional chemotherapy might be difficult in the context of intensive treatment protocols.

Impact of Antibodies Against Polyethylene Glycol on the Pharmacokinetics of PEGylated Asparaginase in Children with Acute Lymphoblastic Leukaemia: A Population Pharmacokinetic Approach.

BACKGROUND AND OBJECTIVES: Besides allergic reactions, antibodies against polyethylene glycol (PEG) have been associated with reduced PEG-asparaginase (PEG-ASNase) activity. Population pharmacokinetics (popPK) allow for an in-depth investigation of the influence of anti-PEG antibodies on PEG-ASNase pharmacokinetics. METHODS: PEG-ASNase activity (6261 samples) and anti-PEG antibodies (2082/6412 samples prior to/post administration) in 1444 children with acute lymphoblastic leukaemia treated in the AIEOP-BFM ALL 2009 trial were evaluated. Patients received two doses of PEG-ASNase during induction (2500 U/m2, intravenous, biweekly) and a third dose during reinduction treatment. Anti-PEG IgG and IgM measured prior to and post administration were explored for their influence on the initial clearance of PEG-ASNase using a previously established popPK model. Categorical and continuous antibody data, including each isotype individually as well as in combination, were assessed. RESULTS: High pre-existing levels of anti-PEG antibodies increase the initial drug clearance. Analysed separately, both anti-PEG IgGprior and IgMprior were significant covariates; the stronger effect was observed for anti-PEG IgMprior. Hockey stick models best described the data. For anti-PEG IgMprior, each additional log unit above the estimated cut point was related to a 41.4% increase in initial clearance after the first dose in induction. Antibody levels below the cut point were not associated with an effect on clearance. The combination of both isotypes did not provide additional information compared to anti-PEG IgMprior alone. Antibody levels post administration were not associated with an effect on clearance. CONCLUSION: Pre-existing antibodies against PEG-ASNase significantly increased the initial clearance in a subgroup of patients showing high antibody levels. (Trial registration: EU clinical trials register; EudraCT No: 2007-004270-43; first registered 23 October 2009.).

Population Pharmacokinetics of PEGylated Asparaginase in Children with Acute Lymphoblastic Leukemia: Treatment Phase Dependency and Predictivity in Case of Missing Data.

BACKGROUND AND OBJECTIVES: The pharmacokinetics of polyethylene glycol-conjugated asparaginase (PEG-ASNase) are characterized by an increase in elimination over time, a marked increase in ASNase activity levels from induction to reinduction, and high inter- and intraindividual variability. A population pharmacokinetic (PopPK) model is required to estimate individual dose intensity, despite gaps in monitoring compliance. METHODS: In the AIEOP-BFM ALL 2009 trial, two PEG-ASNase administrations (2500 U/m2 intravenously) during induction (14-day interval) and one administration during reinduction were administered in children with acute lymphoblastic leukemia. ASNase activity levels were monitored weekly. A PopPK model was used for covariate modeling and external validation. The predictivity of the model in case of missing data was tested for observations, as well as for the derived parameters of the area under the concentration time curve (AUC0-∞) and time above different thresholds. RESULTS: Compared to the first administration in induction (1374 patients, 6069 samples), the initial clearance and volume of distribution decreased by 11.0% and 15.9%, respectively, during the second administration during induction and by 41.2% and 28.4% during reinduction. Furthermore, the initial clearance linearly increased for children aged > 8 years and was 7.1% lower for females. The model was successfully externally validated (1253 patients, 5523 samples). In case of missing data, > 52% of the predictions for observations and > 82% for derived parameters were within ± 20% of the nominal value. CONCLUSION: A PopPK model that describes the complex pharmacokinetics of PEG-ASNase was successfully externally validated. AUC0-∞ or time above different thresholds, which are parameters describing dose intensity, can be estimated with high predictivity, despite missing data. ( www.clinicaltrials.gov , NCT01117441, first submitted date: May 3, 2010).

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.

A pharmacological study on pegylated asparaginase used in front-line treatment of children with acute lymphoblastic leukemia.

BACKGROUND AND OBJECTIVES: Pegylated-asparaginase (PEG-ASP) has been traditionally used as a second-line preparation in children with acute lymphoblastic leukemia (ALL) presenting with clinical allergy to native asparaginase (ASP) products. The main goal of the present study was to investigate the pharmacological effects of the administration of PEG-ASP given as a first-line product in children with ALL. DESIGN AND METHODS: PEG-ASP serum enzymatic activity and serum and cerebrospinal fluid (CSF) levels of asparagine were investigated in 20 children with newly diagnosed ALL enrolled in the ongoing AIEOP ALL 2000 protocol and treated with PEG-ASP as a first-line ASP preparation. During induction the drug was administered at the dosage of 1,000 U/m2 i.v. on days 12 and 27. During reinduction the drug was administered only once at the same dosage. RESULTS: Among the 20 patients treated in induction serum PEG-ASP activity equalled or exceeded 100 U/L in 18/18, 11/11 and 15/18 of the samples available on days 22, 25 and 27, respectively, and in 16/16, 12/15 and 5/8 samples available on days 36, 39 and 45, respectively. In the 15 patients treated during reinduction serum PEG-ASP activity > or =100 U/L was observed in 14/15, 11/14, 6/10, and 0/12 samples available on days 11, 15, 18 and 23, respectively, after the administration of the drug. Serum asparagine levels were below the detection limit (< or =0.2 microM) in all patients/samples and at all time points evaluated during induction; during reinduction only one patient had detectable asparagine levels from day 11. CSF asparagine levels were below the detection limit of the method only in a few patients during both induction and reinduction. INTERPRETATION AND CONCLUSIONS: PEG-ASP given as a first-line ASP product in the context of an intensive chemotherapy protocol for pediatric ALL allowed adequate plasma enzymatic activity and asparagine depletion during both exposures to the drug. However, CSF asparagine depletion was inadequate.

Improved outcome in pediatric relapsed acute myeloid leukemia: results of a randomized trial on liposomal daunorubicin by the International BFM Study Group.

PURPOSE: In pediatric relapsed acute myeloid leukemia (AML), optimal reinduction therapy is unknown. Studies suggest that liposomal daunorubicin (DNX; DaunoXome; Galen, Craigavon, United Kingdom) is effective and less cardiotoxic, which is important in this setting. These considerations led to a randomized phase III study by the International Berlin-Frankfurt-Münster Study Group. PATIENTS AND METHODS: Patients with relapsed or primary refractory non-French-American-British type M3 AML who were younger than 21 years of age were eligible. Patients were randomly assigned to fludarabine, cytarabine, and granulocyte colony-stimulating factor (FLAG) or to FLAG plus DNX in the first reinduction course. The primary end point was status of the bone marrow (BM) sampled shortly before the second course of chemotherapy (the day 28 BM). Data are presented according to intention-to-treat for all 394 randomly assigned patients (median follow-up, 4.0 years). RESULTS: The complete remission (CR) rate was 64%, and the 4-year probability of survival (pOS) was 38% (SE, 3%). The day 28 BM status (available in 359 patients) was good (≤ 20% leukemic blasts) in 80% of patients randomly assigned to FLAG/DNX and 70% for patients randomly assigned to FLAG (P = .04). Concerning secondary end points, the CR rate was 69% with FLAG/DNX and 59% with FLAG (P = .07), but overall survival was similar. However, core-binding factor (CBF) AML treated with FLAG/DNX resulted in pOS of 82% versus 58% with FLAG (P = .04). Grade 3 to 4 toxicity was essentially similar in both groups. CONCLUSION: DNX added to FLAG improves early treatment response in pediatric relapsed AML. Overall long-term survival was similar, but CBF-AML showed an improved survival with FLAG/DNX. International collaboration proved feasible and resulted in the best outcome for pediatric relapsed AML reported thus far.