Continuous PEGasparaginase Dosing Reduces Hypersensitivity Reactions in Pediatric ALL: A Dutch Childhood Oncology Group ALL11 Randomized Trial

PURPOSE

The primary objective of this randomized study was to determine whether a continuous dosing schedule (without the asparaginase-free interval) would result in less hypersensitivity reactions to PEGasparaginase (PEGasp) compared with the standard noncontinuous dosing schedule.

METHODS

Eight hundred eighteen patients (age 1-18 years) with ALL were enrolled in the Dutch Childhood Oncology Group-ALL11 protocol and received PEGasp. Three hundred twelve patients stratified in the medium-risk arm were randomly assigned to receive 14 individualized PEGasp doses once every two weeks in either a noncontinuous or continuous schedule after the first three doses in induction (EudraCT: 2012-000067-25). Hypersensitivity reactions were defined as allergies, allergic-like reactions, and silent inactivation. Secondary end points were other asparaginase-related toxicities, asparaginase activity and antibody levels, and outcome.

RESULTS

During induction, 27 of 818 patients (3.3%) experienced hypersensitivity reactions. After random assignment, 4 of 155 (2.6%) in the continuous treatment arm versus 17 of 157 (10.8%) patients in the noncontinuous treatment arm had hypersensitivity reactions (P < .01), of which two (1.3%) versus 13 (8.3%) were inactivating reactions (P < .01). The occurrence of inactivating hypersensitivity reactions was seven times lower in the continuous arm (odds ratio, 0.15 [0.032-0.653]). In addition, antibody levels were significantly lower in the continuous arm (P < .01). With exception of a lower incidence of increased amylase in the continuous arm, there were no significant differences in total number of asparaginase-associated toxicities between arms. However, the timing of the toxicities was associated with the timing of the asparaginase administrations. No difference in 5-year cumulative incidence of relapse, death, or disease-free survival was found between both treatment arms.

CONCLUSION

A continuous dosing schedule of PEGasp is an effective approach to prevent antibody formation and inactivating hypersensitivity reactions. The continuous PEGasp schedule did not increase toxicity and did not affect the efficacy of the therapy.

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.

Bosutinib in Resistant and Intolerant Pediatric Patients With Chronic Phase Chronic Myeloid Leukemia: Results From the Phase I Part of Study ITCC054/COG AAML1921

PURPOSE

Bosutinib is approved for adults with chronic myeloid leukemia (CML): 400 mg once daily in newly diagnosed (ND); 500 mg once daily in resistant/intolerant (R/I) patients. Bosutinib has a different tolerability profile than other tyrosine kinase inhibitors (TKIs) and potentially less impact on growth (preclinical data). The primary objective of this first-in-child trial was to determine the recommended phase II dose (RP2D) for pediatric R/I and ND patients.

PATIENTS AND METHODS

In the phase I part of this international, open-label trial (ClinicalTrials.gov identifier: NCT04258943), children age 1-18 years with R/I (per European LeukemiaNet 2013) Ph+ CML were enrolled using a 6 + 4 design, testing 300, 350, and 400 mg/m2 once daily with food. The RP2D was the dose resulting in 0/6 or 1/10 dose-limiting toxicities (DLTs) during the first cycle and achieving adult target AUC levels for the respective indication. As ND participants were only enrolled in phase II, the ND RP2D was selected based on data from R/I patients.

RESULTS

Thirty patients were enrolled; 27 were evaluable for DLT: six at 300 mg/m2, 11 at 350 mg/m2 (one DLT), and 10 at 400 mg/m2 (one DLT). The mean AUCs at 300 mg/m2, 350 mg/m2, and 400 mg/m2 were 2.20 μg h/mL, 2.52 μg h/mL, and 2.66 μg h/mL, respectively. The most common adverse event was diarrhea (93%; ≥grade 3: 11%). Seven patients stopped because of intolerance and eight because of insufficient response. Complete cytogenetic and major molecular response to bosutinib appeared comparable with other published phase I/II trials with second-generation TKIs in children.

CONCLUSION

Bosutinib was safe and effective. The pediatric RP2D was 400 mg/m2 once daily (max 600 mg/d) with food in R/I patients and 300 mg/m2 once daily (max 500 mg/d) with food in ND patients, which achieved targeted exposures as per adult experience.

Health-related quality of life and its determinants during and after treatment for paediatric acute lymphoblastic leukaemia: a national, prospective, longitudinal study in the Netherlands

OBJECTIVES

Health-related quality of life (HRQoL) is impaired in paediatric patients with acute lymphoblastic leukaemia (ALL). Over the past decades, ALL treatment has successfully been adjusted to the risk of relapse, which is now reflected by the stratification of patients into three risk groups who receive treatment of differing intensities. This study is the first to evaluate the longitudinal course of HRQoL in light of these adjustments and identify determinants of HRQoL.

DESIGN

Two prospective, national cohort studies (add-on studies within the two most recent treatment protocols for children with ALL (ALL-10 and ALL-11)).

SETTING

Dutch paediatric oncology hospitals between October 2006 and October 2009 (ALL-10) and between August 2013 and July 2017 (ALL-11).

PARTICIPANTS

Patients with ALL (2-18 years) are treated according to the ALL-10 or ALL-11 treatment protocol. Patients treated according to the ALL-10 protocol only completed a cancer-specific QoL measure and patients treated according to the ALL-11 protocol completed both a cancer-specific and generic QoL measure (see below).

OUTCOME MEASURES

HRQoL, assessed with parent-proxy questionnaires (PedsQL Generic and Cancer module) within the first 5 months (T0), at 1 year (T1), 2 years (T2) and 3 years (T3) after diagnosis. The proportion of patients with clinically relevant generic HRQoL impairment was compared with healthy norm values. Multivariable mixed model analyses were used to evaluate the development of HRQoL over time and its medical and sociodemographic determinants (collected on enrolment).

RESULTS

Of the ALL-10 cohort, 132 families participated and of the ALL-11 cohort, 136 families participated (268 total). Thus, cancer-specific HRQoL assessments were available for 268 patients (median age 5.3 years (IQR 6.15), 56.0% boys, 69.0% medium-risk ALL), and generic HRQoL assessments for 136 patients (median age 4.8 years (IQR 6.13), 60.3% boys, 75.0% medium-risk ALL). Generic HRQoL improved between timepoints T0 and T3 (total score B 16.1, 95% CI 12.2 to 20.1, p<0.001), but did not restore to normal 1 year after the end of treatment: 28.0% of children remained impaired compared with 16% in the general population (p=0.003). Cancer-specific HRQoL generally improved from T0 to T2 (Pain B 11.3, 95% CI 7.1 to 15.5; Nausea B 11.7, 8.4 to 15.1; Procedural Anxiety B 19.1, 14.8 to 23.4; Treatment Anxiety B 12.8, 9.5 to 16.0; Worry B 3.5, 0.6 to 6.3; Communication B 8.5, 5.0 to 11.9; all p<0.001 except for Worry (p=0.02)), while Physical Appearance and Cognitive Functioning remained stable. Higher treatment intensity and experiencing pain or simultaneous chronic illness were associated with lower HRQoL over time for multiple subscales.

CONCLUSIONS

HRQoL impairment is prevalent during and after ALL treatment. Patients with standard-risk ALL and reduced treatment intensity have better HRQoL than patients in higher risk groups. Systematic monitoring of HRQoL is of utmost importance in order to provide timely psychosocial interventions and supportive care.

Randomized controlled trial on the effect of 1-hour infusion of vincristine versus push injection on neuropathy in children with cancer (final analysis)

INTRODUCTION

Vincristine is an integral component of treatment for children with cancer. Its main dose-limiting side effect is vincristine-induced peripheral neuropathy (VIPN). The VINCA trial was a randomized controlled trial that explored the effect of 1-hour infusion compared with push injection of vincristine on the development of VIPN in children with cancer. The short-term outcomes (median follow-up 9 months) showed that there was no difference in VIPN between the randomization groups. However, 1-hour infusion was less toxic in children who also received azoles. We now report the results of the final analyses (median follow-up 20 months), which includes treatment outcome as a secondary objective (follow-up 3 years).

METHODS

VIPN was measured 1-7 times per participant using the Common Terminology Criteria for Adverse Events (CTCAE) and the pediatric-modified total neuropathy score. Poisson mixed model and logistic generalized estimating equation analysis for repeated measures were performed.

RESULTS

Forty-five participants per randomization group were included. There was no significant effect of 1-hour infusion compared with push injection on VIPN. In participants receiving concurrent azoles, the total CTCAE score was significantly lower in the one-hour group (rate ratio 0.52, 95% confidence interval 0.33-0.80, p = 0.003). Four patients in the one-hour group and one patient in the push group relapsed. Two patients in the one-hour group died.

CONCLUSION

1-hour infusion of vincristine is not protective against VIPN. However, in patients receiving concurrent azoles, 1-hour infusion may be less toxic. The difference in treatment outcome is most likely the result of differences in risk profile.

Blinatumomab Added to Chemotherapy in Infant Lymphoblastic Leukemia

BACKGROUND

KMT2A-rearranged acute lymphoblastic leukemia (ALL) in infants is an aggressive disease with 3-year event-free survival below 40%. Most relapses occur during treatment, with two thirds occurring within 1 year and 90% within 2 years after diagnosis. Outcomes have not improved in recent decades despite intensification of chemotherapy.

METHODS

We studied the safety and efficacy of blinatumomab, a bispecific T-cell engager molecule targeting CD19, in infants with KMT2A-rearranged ALL. Thirty patients younger than 1 year of age with newly diagnosed KMT2A-rearranged ALL were given the chemotherapy used in the Interfant-06 trial with the addition of one postinduction course of blinatumomab (15 μg per square meter of body-surface area per day; 28-day continuous infusion). The primary end point was clinically relevant toxic effects, defined as any toxic effect that was possibly or definitely attributable to blinatumomab and resulted in permanent discontinuation of blinatumomab or death. Minimal residual disease (MRD) was measured by polymerase chain reaction. Data on adverse events were collected. Outcome data were compared with historical control data from the Interfant-06 trial.

RESULTS

The median follow-up was 26.3 months (range, 3.9 to 48.2). All 30 patients received the full course of blinatumomab. No toxic effects meeting the definition of the primary end point occurred. Ten serious adverse events were reported (fever [4 events], infection [4], hypertension [1], and vomiting [1]). The toxic-effects profile was consistent with that reported in older patients. A total of 28 patients (93%) either were MRD-negative (16 patients) or had low levels of MRD (<5×10^-4 [i.e., <5 leukemic cells per 10,000 normal cells], 12 patients) after the blinatumomab infusion. All the patients who continued chemotherapy became MRD-negative during further treatment. Two-year disease-free survival was 81.6% in our study (95% confidence interval [CI], 60.8 to 92.0), as compared with 49.4% (95% CI, 42.5 to 56.0) in the Interfant-06 trial; the corresponding values for overall survival were 93.3% (95% CI, 75.9 to 98.3) and 65.8% (95% CI, 58.9 to 71.8).

CONCLUSIONS

Blinatumomab added to Interfant-06 chemotherapy appeared to be safe and had a high level of efficacy in infants with newly diagnosed KMT2A-rearranged ALL as compared with historical controls from the Interfant-06 trial. (Funded by the Princess Máxima Center Foundation and others; EudraCT number, 2016-004674-17.).

Safety of mRNA-based COVID-19 vaccination in paediatric patients with a PEG-asparaginase allergy

Background

Children treated for a malignancy are at risk to develop serious illness from a COVID-19 infection. Pegylated E. coli asparaginase (PEG-asparaginase) is used in the treatment of acute lymphoblastic leukemia. Allergy to this drug is common and both asparaginase and polyethylene glycol (PEG) are identified as possible antigens. The mRNA-based vaccines against COVID-19 contain PEG as a stabilizing component.

Methods

We developed a protocol to be able to safely vaccinate children with a PEG-asparaginase allergy. All patients with a history of allergy to PEG-asparaginase have been included and skin prick testing for various PEGs was performed before vaccination with the mRNA Pfizer-BioNTech COVID-19 vaccine.

Results

Twelve children between six and 16 years old were vaccinated, without allergic reaction. None of them got a positive skin prick test for PEG. Ten patients had pre-existing IgG or IgM antibodies against PEG.

Conclusion

Children with a PEG-asparaginase allergy can be safely vaccinated against COVID-19 with mRNA vaccines containing PEG irrespective of IgG/IgM antibodies to PEG-asparaginase. Routine skin prick testing in patients with PEG-asparaginase allergy does not seem to be of added value.

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.

Genetic Polymorphisms Associated with Vincristine Pharmacokinetics and Vincristine-Induced Peripheral Neuropathy in Pediatric Oncology Patients

Simple Summary

Vincristine is a type of chemotherapy that is often used in the treatment of children with cancer. The main side effect of vincristine is nerve damage. Patients experience symptoms such as tingling, pain or muscle weakness. Some children are more sensitive to vincristine than others, which may depend on variations in genes and in the breakdown of vincristine by the body. In this study, we investigated the effect of variations in genes on nerve damage due to vincristine and breakdown of vincristine by the body. We found that nine variations in seven genes were associated with nerve damage due to vincristine, whereas three variations in three genes were associated with the breakdown of vincristine by the body. It is important that future studies try to replicate these findings. Our findings help us towards the goal of tailoring vincristine treatment to each child, with optimal therapeutic effect while limiting nerve damage.

Abstract

Vincristine (VCR) is an important component of curative chemotherapy for many childhood cancers. Its main side effect is VCR-induced peripheral neuropathy (VIPN), a dose limiting toxicity. Some children are more susceptible to VIPN, which is at least partially dependent on genetic factors and pharmacokinetics (PK). In this study, we identify and replicate genetic variants associated with VCR PK and VIPN. Patient samples from a randomized clinical trial studying the effect of administration duration of VCR on VIPN in 90 patients were used. PK sampling was conducted on between one and five occasions at multiple time points. A linear two-compartment model with first-order elimination was used, and targeted next-generation DNA sequencing was performed. Genotype–trait associations were analyzed using mixed-effect models or logistic regression analysis for repeated measures, or Poisson regression analysis in which the highest VIPN score per patient was included. Nine single-nucleotide polymorphisms (SNPs) in seven genes (NDRG1, GARS, FIG4, FGD4, SEPTIN9, CEP72, and ETAA1) were associated with VIPN. Furthermore, three SNPs in three genes (MTNR1B, RAB7A and SNU13) were associated with PK of VCR. In conclusion, PK of VCR and VIPN are influenced by SNPs; upfront identification of those that lead to an altered susceptibility to VIPN or VCR exposure could help individualize VCR treatment.

Can Machine Learning Models Predict Asparaginase-associated Pancreatitis in Childhood Acute Lymphoblastic Leukemia

Asparaginase-associated pancreatitis (AAP) frequently affects children treated for acute lymphoblastic leukemia (ALL) causing severe acute and persisting complications. Known risk factors such as asparaginase dosing, older age and single nucleotide polymorphisms (SNPs) have insufficient odds ratios to allow personalized asparaginase therapy. In this study, we explored machine learning strategies for prediction of individual AAP risk. We integrated information on age, sex, and SNPs based on Illumina Omni2.5exome-8 arrays of patients with childhood ALL (N=1564, 244 with AAP 1.0 to 17.9 yo) from 10 international ALL consortia into machine learning models including regression, random forest, AdaBoost and artificial neural networks. A model with only age and sex had area under the receiver operating characteristic curve (ROC-AUC) of 0.62. Inclusion of 6 pancreatitis candidate gene SNPs or 4 validated pancreatitis SNPs boosted ROC-AUC somewhat (0.67) while 30 SNPs, identified through our AAP genome-wide association study cohort, boosted performance (0.80). Most predictive features included rs10273639 (PRSS1-PRSS2), rs10436957 (CTRC), rs13228878 (PRSS1/PRSS2), rs1505495 (GALNTL6), rs4655107 (EPHB2) and age (1 to 7 y). Second AAP following asparaginase re-exposure was predicted with ROC-AUC: 0.65. The machine learning models assist individual-level risk assessment of AAP for future prevention trials, and may legitimize asparaginase re-exposure when AAP risk is predicted to be low.

Hypersensitivity to Pegylated E.colia sparaginase as first-line treatment in contemporary paediatric acute lymphoblastic leukaemia protocols: a meta-analysis of the Ponte di Legno Toxicity working group

BACKGROUND

Hypersensitivity reactions to asparaginase challenge its use and occur frequently (30-75%) after native Escherichia Coli (E.coli) asparaginase. Comparison of incidence of allergic reactions to pegylated E.coli asparaginase (PEGasparaginase) across contemporary paediatric acute lymphoblastic leukaemia (ALL) protocols is lacking.

METHOD AND PATIENTS

Questionnaires were sent to all members of the international ALL Ponte di Legno Toxicity Working Group. Meta-analyses were conducted to estimate the incidence of three types of hypersensitivity (allergy, allergic-like reaction and silent inactivation). Information on protocol level regarding PEGasparaginase dosing regimen, administration route and use of therapeutic drug monitoring was collected for risk analysis.

RESULTS

Newly diagnosed patients with ALL (n = 5880), aged 1-24 years old, were enrolled in seven different upfront ALL protocols using PEGasparaginase as first-line treatment. The incidence of allergic reactions (sum of allergies and allergic-like reactions) [95% confidence interval] was 2% [1%; 3%] during induction and 8% [5%; 11%] during postinduction. Route of administration, number of doses, dosage and number of PEGasparaginase-free weeks did not significantly influence risk of hypersensitivity. Multivariate meta-regression analysis suggests that initiation of PEGasparaginase in postinduction and higher number of PEGasparaginase-free intervals increased the risk for allergic reactions. 9-16% and 23-29% of all hypersensitivities were allergic-like reactions and silent inactivation, respectively.

CONCLUSION

The incidence of allergic reactions is lower in protocols using PEGasparaginase as first-line treatment compared with that reported for E.coli asparaginase or PEGasparaginase after E.coli asparaginase. Postinduction phase, a higher number of PEGasparaginase-free intervals, and initiation of PEGasparaginase in postinduction phase are risk factors for allergic reactions. These results are important for planning of PEGasparaginase administrations in future frontline therapy.

A Validated Risk Prediction Model for Bone Fragility in Children With Acute Lymphoblastic Leukemia

Although bone fragility may already be present at diagnosis of pediatric acute lymphoblastic leukemia (ALL), routine performance of dual-energy X-ray absorptiometry (DXA) in every child is not universally feasible. The aim of this study was to develop and validate a risk prediction model for low lumbar spine bone mineral density (LS BMD Z-score ≤ -2.0) at diagnosis, as an important indicator for fracture risk and further treatment-related BMD aggravation. Children with ALL (4-18 years), treated according to the Dutch Childhood Oncology Group protocol (DCOG-ALL9; model development; n = 249) and children from the Canadian Steroid-Associated Osteoporosis in the Pediatric Population cohort (STOPP; validation; n = 99) were included in this study. Multivariable logistic regression analyses were used to develop the prediction model and to confirm the association of low LS BMD at diagnosis with symptomatic fractures during and shortly after cessation of ALL treatment. The area under the receiver operating characteristic curve (AUC) was used to assess model performance. The prediction model for low LS BMD at diagnosis using weight (β = -0.70) and age (β = -0.10) at diagnosis revealed an AUC of 0.71 (95% CI, 0.63-0.78) in DCOG-ALL9 and 0.74 (95% CI, 0.63-0.84) in STOPP, and resulted in correct identification of 71% of the patients with low LS BMD. We confirmed that low LS BMD at diagnosis is associated with LS BMD at treatment cessation (OR 5.9; 95% CI, 3.2-10.9) and with symptomatic fractures (OR 1.7; 95% CI, 1.3-2.4) that occurred between diagnosis and 12 months following treatment cessation. In meta-analysis, LS BMD at diagnosis (OR 1.6; 95% CI, 1.1-2.4) and the 6-month cumulative glucocorticoid dose (OR 1.9; 95% CI, 1.1-3.2) were associated with fractures that occurred in the first year of treatment. In summary, a prediction model for identifying pediatric ALL patients with low LS BMD at diagnosis, as an important indicator for bone fragility, was successfully developed and validated. This can facilitate identification of future bone fragility in individual pediatric ALL patients. © 2021 American Society for Bone and Mineral Research (ASBMR).

The association between vincristine-induced peripheral neuropathy and health-related quality of life in children with cancer

Purpose

Vincristine (VCR) is a chemotherapeutic agent used in the treatment of pediatric oncology patients, but its main toxicity is VCR‐induced peripheral neuropathy (VIPN). However, whether VIPN has an effect on health‐related quality of life (HR‐QoL) in children during treatment is unknown. Therefore, the aim of our study was to investigate the association between VIPN and HR‐QoL in children starting treatment for cancer.

Methods

Measurements of VIPN were performed using two tools: Common Terminology Criteria for Adverse Events (CTCAE) and pediatric‐modified Total Neuropathy Score (ped‐mTNS). Assessment of HR‐QoL was done with self‐ and proxy assessment of the Cancer and Generic module of the Pediatric Cancer Quality of Life Inventory™ (PedsQL).

Results

In total, N = 86 children were included. HR‐QoL of children with VIPN (n = 67%, 76%) was significantly lower in comparison with children without VIPN: estimated Total score of PedsQL Generic (proxy) 84.57; β = −8.96 and 95% confidence interval (CI) −14.48 to −3.43; p = 0.002, estimated PedsQL Generic Total score (self‐reported): 85.16, β = −8.38 (95% CI: −13.76 to −3.00); p = 0.003. Similar results were found in the Pain and Hurt domain of the PedsQL Cancer (pain: estimated score [proxy]: 85.28, β = −9.94 [95%CI: −16.44 to −3.45], p = 0.003; hurt: estimated score [self‐report] 97.57, β = −19.15 [95%CI: −26.82 to −11.48], p < 0.001).

Conclusion

VIPN results in a significant reduction of HR‐QoL in children under treatment for a malignancy, which means that VIPN is important for the well‐being of pediatric oncology patients. Therefore, this study underlines the importance of optimizing treatment with VCR, thereby aiming to reduce VIPN while maintaining efficacy.

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.

Vitamin D supplementation for children with cancer: A systematic review and consensus recommendations

Background

Prevalent vitamin D deficiency (VDD) and low bone mineral density (BMD) have led to vitamin D supplementation for children with cancer, regardless vitamin D status. However, it remains unsettled whether this enhances bone strength. We sought to address this issue by carrying out a systematic review of the literature.

Methods

We conducted a literature search using PubMed, Embase, and Cochrane databases. Studies including children up to 5 years after cancer therapy were assessed for the association between 25‐hydroxyvitamin D (25OHD) levels and BMD Z‐scores or fractures, and the effect of vitamin D supplementation on BMD or fractures. Evidence quality was assessed using the GRADE methodology.

Results

Nineteen studies (16 observational and 3 interventional, mainly involving children with hematologic malignancies) were included. One study which analyzed 25OHD as a threshold variable (≤10 ng/ml) found a significant association between 25OHD levels and BMD Z‐scores, while 25OHD as a continuous variable was not significantly associated with BMD Z‐scores in 14 observational studies. We found neither a significant association between lower 25OHD levels and fractures (2 studies), nor between vitamin D (and calcium) supplementation and BMD or fracture frequency (3 studies) (very low quality evidence).

Conclusion

There is a lack of evidence for an effect of vitamin D (and calcium) supplementation on BMD or fractures in children with cancer. Further research is needed; until then, we recommend dietary vitamin D/calcium intake in keeping with standard national guidelines, and periodic 25OHD monitoring to detect levels <20 ng/ml. Vitamin D/calcium supplementation is recommended in children with low levels, to maintain levels ≥20 ng/ml year‐long.

Evaluation of the pharmacokinetics of prednisolone in paediatric patients with acute lymphoblastic leukaemia treated according to Dutch Childhood Oncology Group protocols and its relation to treatment response

Glucocorticoids form the backbone of paediatric acute lymphoblastic leukaemia (ALL) treatment. Many studies have been performed on steroid resistance; however, few studies have addressed the relationship between dose, concentration and clinical response. The aim of the present study was to evaluate the pharmacokinetics of prednisolone in the treatment of paediatric ALL and the correlation with clinical parameters. A total of 1028 bound and unbound prednisolone plasma concentrations were available from 124 children (aged 0–18 years) with newly diagnosed ALL enrolled in the Dutch Childhood Oncology Group studies. A population pharmacokinetic model was developed and post hoc area under the curve (AUC) was tested against treatment outcome parameters. The pharmacokinetics of unbound prednisolone in plasma was best described with allometric scaling and saturable binding to proteins. Plasma protein binding decreased with age. The AUC of unbound prednisolone was not associated with any of the disease parameters or treatment outcomes. Unbound prednisolone plasma concentrations correlated with age. No effect of exposure on clinical treatment outcome parameters was observed and does not substantiate individualised dosing. Poor responders, high‐risk and relapsed patients showed a trend towards lower exposure compared to good responders. However, the group of poor responders was small and requires further research.

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.

Clinical Implications of Minimal Residual Disease Detection in Infants With KMT2A-Rearranged Acute Lymphoblastic Leukemia Treated on the Interfant-06 Protocol

PURPOSE

Infant acute lymphoblastic leukemia (ALL) is characterized by a high incidence of KMT2A gene rearrangements and poor outcome. We evaluated the value of minimal residual disease (MRD) in infants with KMT2A-rearranged ALL treated within the Interfant-06 protocol, which compared lymphoid-style consolidation (protocol IB) versus myeloid-style consolidation (araC, daunorubicin, etoposide/mitoxantrone, araC, etoposide).

MATERIALS AND METHODS

MRD was measured in 249 infants by DNA-based polymerase chain reaction of rearranged KMT2A, immunoglobulin, and/or T-cell receptor genes, at the end of induction (EOI) and end of consolidation (EOC). MRD results were classified as negative, intermediate (< 5 × 10-4), and high (≥ 5 × 10-4).

RESULTS

EOI MRD levels predicted outcome with 6-year disease-free survival (DFS) of 60.2% (95% CI, 43.2 to 73.6), 45.0% (95% CI, 28.3 to 53.1), and 33.8% (95% CI, 23.8 to 44.1) for infants with negative, intermediate, and high EOI MRD levels, respectively (P = .0039). EOC MRD levels were also predictive of outcome, with 6-year DFS of 68.2% (95% CI, 55.2 to 78.1), 40.1% (95% CI, 28.1 to 51.9), and 11.9% (95% CI, 2.6 to 29.1) for infants with negative, intermediate, and high EOC MRD levels, respectively (P < .0001). Analysis of EOI MRD according to the type of consolidation treatment showed that infants treated with lymphoid-style consolidation had 6-year DFS of 78.2% (95% CI, 51.4 to 91.3), 47.2% (95% CI, 33.0 to 60.1), and 23.2% (95% CI, 12.1 to 36.4) for negative, intermediate, and high MRD levels, respectively (P < .0001), while for myeloid-style-treated patients the corresponding figures were 45.0% (95% CI, 23.9 to 64.1), 41.3% (95% CI, 23.2 to 58.5), and 45.9% (95% CI, 29.4 to 60.9).

CONCLUSION

This study provides support for the idea that induction therapy selects patients for subsequent therapy; infants with high EOI MRD may benefit from AML-like consolidation (DFS 45.9% v 23.2%), whereas patients with low EOI MRD may benefit from ALL-like consolidation (DFS 78.2% v 45.0%). Patients with positive EOC MRD had dismal outcomes. These findings will be used for treatment interventions in the next Interfant protocol.

Parental functioning during maintenance treatment for childhood acute lymphoblastic leukemia: Effects of treatment intensity and dexamethasone pulses

BACKGROUND

During maintenance treatment, Dutch pediatric patients with medium-risk (MR) acute lymphoblastic leukemia (ALL) receive intravenous chemotherapy and cyclic dexamethasone. Dexamethasone affects child's sleep and behavior. Standard-risk (SR) patients only receive oral chemotherapy, without dexamethasone. Effects of stratified therapy on parents are not well known. This study compares parental sleep, distress and quality of life (QoL) with the general population, between MR and SR groups, and on- and off-dexamethasone (MR group).

PROCEDURE

One year after diagnosis, parents of MR patients completed the Medical Outcomes Study (MOS) sleep, distress thermometer for parents and Short Form-12 (SF-12) twice; once on-dexamethasone and once off-dexamethasone. SR parents completed one measurement. Sleep problems, distress and QoL scores (off-dexamethasone) were compared to reference values and between MR and SR. Score differences on- and off-dexamethasone were assessed by multilevel regression analysis.

RESULTS

Parents (80% mothers) of 121 patients (57% males; 75% MR, 25% SR) completed 191 measurements. Compared to reference values, parents reported more sleep disturbances, higher distress, and lower mental QoL. Additionally, MR parents reported clinical distress (score ≥ 4), whereas SR parents (on average) did not (mean 4.8 ± 2.4 vs 3.5 ± 2.4, P = .02). Within the MR group, outcomes did not significantly differ on- and off-dexamethasone.

CONCLUSIONS

Parents of ALL patients report sleep problems, high distress, and QoL impairment. Within the MR group, parental functioning did not differ on- and off-dexamethasone. However, MR parents reported clinical distress more often than SR parents, possibly reflecting differences in prognostic estimates and treatment burden. This perhaps includes the overall strain of cyclic dexamethasone. This study highlights the need for psychosocial support throughout treatment, regardless of risk stratification.

Progress against childhood and adolescent acute lymphoblastic leukaemia in the Netherlands, 1990-2015

We assessed the epidemiologic progress against childhood and adolescent acute lymphoblastic leukaemia (ALL) in the Netherlands over a 26 year period. ALL patients <18 years were selected from the Netherlands Cancer Registry and the Dutch Childhood Oncology Group. Trend analyses were performed over time and by age group and ALL subtype. Between 1990 and 2015, 2997 ALL patients were diagnosed, i.e. 115 patients (range 87-147) per year. Overall incidence remained stable at 37 per million children, despite increases for B-cell precursor ALL (BCP-ALL) at age 10-14 years (AAPC + 1.4%, p = 0.04) and T-cell ALL at 15-17 years (AAPC + 3.7%, p = 0.01). Five-year survival increased from 80% in 1990-94 to 91% in 2010-15 (p < 0.01). Mortality decreased by 4% annually (p < 0.01). Patients 15-17 years were increasingly treated in a paediatric oncology centre, from 35% in 1990-94 to 87% in 2010-15 and experienced a 70% reduction of risk of death compared to those treated outside such a centre (p < 0.01). Significant progress against childhood ALL has been made in the Netherlands, visible by improved survival rates coinciding with declining mortality rates. These outcomes were accompanied by stable incidence rates, despite increases for BCP-ALL at age 10-14 years and T-cell ALL at age 15-17 years.

Pharmacokinetics and population pharmacokinetics in pediatric oncology

Pharmacokinetic research has become increasingly important in pediatric oncology as it can have direct clinical implications and is a crucial component in individualized medicine. Population pharmacokinetics has become a popular method especially in children, due to the potential for sparse sampling, flexible sampling times, computing of heterogeneous data, and identification of variability sources. However, population pharmacokinetic reports can be complex and difficult to interpret. The aim of this article is to provide a basic explanation of population pharmacokinetics, using clinical examples from the field of pediatric oncology, to facilitate the translation of pharmacokinetic research into the daily clinic.

Experience with ponatinib in paediatric patients with leukaemia

Ponatinib has proven to be effective in adults with Philadelphia chromosome-positive leukaemias, but data in paediatrics are scarce. Among paediatric patients with chronic myeloid leukaemia (n = 9) or acute lymphoblastic leukaemia (n = 12) treated with varying doses of ponatinib in 13 centres, 71% showed a decrease in disease burden after a median of three months. Ponatinib was well tolerated, with grade 3 toxicities occurring in 29% of patients. Toxicities were similar to those reported in adults, with the exception of arterial thrombotic events, which were not observed. Ponatinib has a favourable safety profile in this paediatric cohort, but dose-finding studies are needed.

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.

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

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

Impact of dose adaptations following voriconazole therapeutic drug monitoring in pediatric patients

Voriconazole is the mainstay of treatment for invasive aspergillosis in immunocompromised pediatric patients. Although Therapeutic Drug Monitoring (TDM) of voriconazole is recommended, it remains unknown if TDM-based dose adaptations result in target attainment. Patients <19 years from two pediatric hematologic-oncology wards were retrospectively identified based on unexplained high voriconazole trough concentrations (Cmin > 6 mg/l). Patient demographics, clinical characteristics, treatment, voriconazole dosing information, voriconazole Cmin before and after adjustment based on TDM were obtained. Twenty-one patients, median (range) age 7.0 (1.2-18.5) years, were identified in two centers. First Cmin (3.1 mg/l [0.1-13.5]) was obtained after 3 days (1-27) of treatment. The median of all Cmin (n = 485, median 11 per patient) was 2.16 mg/l (0.0 (undetectable)-28.0), with 24.1% of Cmin < 1 mg/l, 48.9% 1-4 mg/l, 9.3% 4-6 mg/l, and 17.7% > 6 mg/l. Intrapatient variability was large (94.1% for IV, 88.5% for PO). Dose increases at Cmin < 1 mg/l resulted in an increased Cmin in 76.4%, with 60% between 1 and 4 mg/l. Dose decreases at Cmin > 6 mg/l resulted in a decreased Cmin in 80%, with 51% between 1 and 4 mg/l. Overall, in 45% of the cases (33 out of 55 and 12 out of 45) therapeutic targets were attained after dose adjustment. Fifty-five percent of initial Cmin was outside the therapeutic target of 1-4 mg/l, with multiple dose adaptations required to achieve therapeutic concentrations. Only 60% and 51% of dose adaptations following sub- and supra-therapeutic Cmin, respectively, did result in target attainment. Intensive and continuous TDM of voriconazole is a prerequisite for ensuring adequate exposure in pediatric patients.

The effect of asparaginase therapy on methotrexate toxicity and efficacy in children with acute lymphoblastic leukemia

Asparaginase and methotrexate (MTX), both essential for pediatric acute lymphoblastic leukemia therapy, are often used concomitantly. Depending on the sequence, in vitro, asparaginase inhibits MTX-polyglutamate (MTXPG) formation, and side effects overlap. MTX toxicity and efficacy, reflected by intracellular erythrocyte MTXPG's, were compared between children treated with and without asparaginase during high dose MTX (HD-MTX) courses of the DCOG ALL-11 protocol (NL50250.078.14). Seventy-three patients, of whom 23 received asparaginase during the HD-MTX courses, were included. Grade 3-4 leukopenia and neutropenia occurred more often (59% and 86% vs. 30% and 62%). The number of infections, grade 3-4 hepatotoxicity, nephrotoxicity, and neurotoxicity did not differ. Patients with asparaginase had lower MTXPG levels, although to a lesser extent than in vitro studies. Although patients with asparaginase during HD-MTX courses showed more myelosuppression, this had no (serious) clinical consequences. Regarding the MTX efficacy, the schedule-related antagonism seen in in vitro seems less important in vivo.

Venous thromboembolism in a large cohort of children with acute lymphoblastic leukemia: Risk factors and effect on prognosis

BACKGROUND

Venous thromboembolism (VTE) is relatively common in children with acute lymphoblastic leukemia (ALL). Thrombotic risk factors in ALL are asparaginase and steroids. However, within the ALL populations treated on the same regimen, it is less clear which other risk factors play a role. Furthermore, few data are available on the effect of VTE on ALL outcomes.

METHODS

In 778 children (1-18 years) with newly diagnosed precursor-B-lineage or T-lineage ALL, treated in the Dutch Childhood Oncology Group (DCOG) ALL-10 protocol in the Netherlands (October 2004 to April 2013), we conducted a nested case control study with 59 VTE cases and 118 controls to identify risk factors for VTE.

RESULTS

Fifty-nine of 778 ALL patients developed VTE (7.6%), with cerebral venous sinus thrombosis (CVST) in 26 of 59 patients (44.1%). VTE occurred during induction treatment in 59.3% (n = 35) and in 40.7% (n = 24) during medium risk intensification. Conditional multivariable logistic regression analysis showed that age and ALL subtype were significantly associated with VTE (age ≥7 years: OR 2.72, 95% CI 1.33-5.57; ALL subtype T-ALL: OR 2.95, 95% CI 1.02-8.57). A multivariable Cox model showed no association between the occurrence of VTE and event free survival. In CVST patients, permanent disability was present in 34.6%.

CONCLUSION

Within this large pediatric ALL cohort, we demonstrated a high morbidity in CVST patients. Age ≥7 years at diagnosis and T-ALL subtype were the main risk factors for VTE, and should be considered in preventive strategies.

Trypsin-encoding PRSS1-PRSS2 variations influence the risk of asparaginase-associated pancreatitis in children with acute lymphoblastic leukemia: a Ponte di Legno toxicity working group report

Asparaginase-associated pancreatitis is a life-threatening toxicity to childhood acute lymphoblastic leukemia treatment. To elucidate genetic predisposition and asparaginase-associated pancreatitis pathogenesis, ten trial groups contributed remission samples from patients aged 1.0-17.9 years treated for acute lymphoblastic leukemia between 2000 and 2016. Cases (n=244) were defined by the presence of at least two of the following criteria: (i) abdominal pain; (ii) levels of pancreatic enzymes ≥3 × upper normal limit; and (iii) imaging compatible with pancreatitis. Controls (n=1320) completed intended asparaginase therapy, with 78% receiving ≥8 injections of pegylated-asparaginase, without developing asparaginase-associated pancreatitis. rs62228256 on 20q13.2 showed the strongest association with the development of asparaginase-associated pancreatitis (odds ratio=3.75; P=5.2×10-8). Moreover, rs13228878 (OR=0.61; P=7.1×10-6) and rs10273639 (OR=0.62; P=1.1×10-5) on 7q34 showed significant association with the risk of asparaginase-associated pancreatitis. A Dana Farber Cancer Institute ALL Consortium cohort consisting of patients treated on protocols between 1987 and 2004 (controls=285, cases=33), and the Children's Oncology Group AALL0232 cohort (controls=2653, cases=76) were available as replication cohorts for the 20q13.2 and 7q34 variants, respectively. While rs62228256 was not validated as a risk factor (P=0.77), both rs13228878 (P=0.03) and rs10273639 (P=0.04) were. rs13228878 and rs10273639 are in high linkage disequilibrium (r2=0.94) and associated with elevated expression of the PRSS1 gene, which encodes for trypsinogen, and are known risk variants for alcohol-associated and sporadic pancreatitis in adults. Intra-pancreatic trypsinogen cleavage to proteolytic trypsin induces autodigestion and pancreatitis. In conclusion, this study finds a shared genetic predisposition between asparaginase-associated pancreatitis and non-asparaginase-associated pancreatitis, and targeting the trypsinogen activation pathway may enable identification of effective interventions for asparaginase-associated pancreatitis.

A cost-effectiveness analysis of Erwinia asparaginase therapy in children with acute lymphoblastic leukemia

OBJECTIVES

Erwinia asparaginase is used as a second-line formulation after a neutralizing hypersensitivity reaction to the first-line formulation of asparaginase. Here, we have performed a cost-effectiveness analysis of Erwinia asparaginase treatment.

METHODS

Children with acute lymphoblastic leukemia treated according to the Dutch Childhood Oncology ALL-10 or ALL-11 protocol were included and initially treated with PEGasparaginase in the intensification phase. The total treatment costs of this treatment phase, quality of life (QoL), and life years saved (LYS) were studied for two scenarios: (a) patients were switched to Erwinia asparaginase treatment after a hypersensitivity reaction, or (b) asparaginase would have been permanently stopped.

RESULTS

Sixty-eight patients were included. There was no difference in QoL between patients with and without a hypersensitivity reaction. The mean costs of the intensification phase per patient were $40,925 if PEGasparaginase could be continued, $175,632 if patients had to switch to Erwinia asparaginase, and $21,190 if asparaginase would have been permanently stopped. An extrapolation of the literature suggests that the 5-year event-free survival would be 10.3% lower without intensive asparaginase treatment if asparaginase is stopped after a reaction. Thus, the costs per LYS were $1892 for scenario 1 and $872 for scenario 2.

CONCLUSIONS

Switching to Erwinia asparaginase increases the costs per LYS by $1020, which is modest in view of the total costs. Moreover, when asparaginase treatment can be completed by switching to Erwinia asparaginase, relapses-and consequential costs-will be avoided. Therefore, from a cost perspective, we recommend a switch to Erwinia asparaginase to complete asparaginase treatment.

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.

Clofarabine, high-dose cytarabine and liposomal daunorubicin in pediatric relapsed/refractory acute myeloid leukemia: a phase IB study

Survival in children with relapsed/refractory acute myeloid leukemia is unsatisfactory. Treatment consists of one course of fludarabine, cytarabine and liposomal daunorubicin, followed by fludarabine and cytarabine and stem-cell transplantation. Study ITCC 020/I-BFM 2009-02 aimed to identify the recommended phase II dose of clofarabine replacing fludarabine in the abovementioned combination regimen (3+3 design). Escalating dose levels of clofarabine (20-40 mg/m²/day × 5 days) and liposomal daunorubicin (40-80 mg/m²/day) were administered with cytarabine (2 g/m²/day × 5 days). Liposomal DNR was given on day 1, 3 and 5 only. The cohort at the recommended phase II dose was expanded to make a preliminary assessment of anti-leukemic activity. Thirty-four children were enrolled: refractory 1^st (n=11), early 1st (n=15), ≥2^nd relapse (n=8). Dose level 3 (30 mg/m²clofarabine; 60 mg/m²liposomal daunorubicin) appeared to be safe only in patients without subclinical fungal infections. Infectious complications were dose-limiting. The recommended phase II dose was 40 mg/m² clofarabine with 60 mg/m² liposomal daunorubicin. Side-effects mainly consisted of infections. The overall response rate was 68% in 31 response evaluable patients, and 80% at the recommended phase II dose (n=10); 22 patients proceeded to stem cell transplantation. The 2-year probability of event-free survival (pEFS) was 26.5±7.6 and probability of survival (pOS) 32.4±8.0%. In the 21 responding patients, the 2-year pEFS was 42.9±10.8 and pOS 47.6±10.9%. Clofarabine exposure in plasma was not significantly different from that in single-agent studies. In conclusion, clofarabine was well tolerated and showed high response rates in relapsed/refractory pediatric acute myeloid leukemia. Patients with (sub) clinical fungal infections should be treated with caution. Clofarabine has been taken forward in the Berlin-Frankfurt-Münster study for newly diagnosed acute myeloid leukemia. The Study ITCC-020 was registered as EUDRA-CT 2009-009457-13; Dutch Trial Registry number 1880.

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.

Asparaginase-associated pancreatitis in childhood acute lymphoblastic leukaemia: an observational Ponte di Legno Toxicity Working Group study

BACKGROUND

Survival for childhood acute lymphoblastic leukaemia surpasses 90% with contemporary therapy; however, patients remain burdened by the severe toxic effects of treatment, including asparaginase-associated pancreatitis. To investigate the risk of complications and risk of re-exposing patients with asparaginase-associated pancreatitis to asparaginase, 18 acute lymphoblastic leukaemia trial groups merged data for this observational study.

METHODS

Patient files from 26 trials run by 18 trial groups were reviewed on children (aged 1·0-17·9 years) diagnosed with t(9;22)-negative acute lymphoblastic leukaemia between June 1, 1996, and Jan 1, 2016, who within 50 days of asparaginase exposure developed asparaginase-associated pancreatitis. Asparaginase-associated pancreatitis was defined by at least two criteria: abdominal pain, pancreatic enzymes at least three times the upper limit of normal (ULN), and imaging compatible with pancreatitis. Patients without sufficient data for diagnostic criteria were excluded. Primary outcomes were defined as acute and persisting complications of asparaginase-associated pancreatitis and risk of re-exposing patients who suffered an episode of asparaginase-associated pancreatitis to asparaginase. Data were collected from Feb 2, 2015, to June 30, 2016, and analysed and stored in a common database at Rigshospitalet, Copenhagen, Denmark.

FINDINGS

Of 465 patients with asparaginase-associated pancreatitis, 33 (8%) of 424 with available data needed mechanical ventilation, 109 (26%) of 422 developed pseudocysts, acute insulin therapy was needed in 81 (21%) of 393, and seven (2%) of 458 patients died. Risk of assisted mechanical ventilation, need for insulin, pseudocysts, or death was associated with older age (median age for patients with complications 10·5 years [IQR 6·4-13·8] vs without complications 6·1 years [IQR 3·6-12·2], p<0·0001), and having one or more affected vital signs (fever, hypotension, tachycardia, or tachypnoea; 96 [44%] of 217 patients with affected vital signs vs 11 [24%] of 46 patients without affected vital signs, p=0·02). 1 year after diagnosis of asparaginase-associated pancreatitis, 31 (11%) of 275 patients still needed insulin or had recurrent abdominal pain or both. Both the risk of persisting need for insulin therapy and recurrent abdominal pain were associated with having had pseudocysts (odds ratio [OR] 9·48 [95% CI 3·01-35·49], p=0·0002 for insulin therapy; OR 11·79 [4·30-37·98], p<0·0001 for recurrent abdominal pain). Within 8 years of asparaginase-associated pancreatitis, risk of abdominal symptoms dropped from 8% (26 of 312) to 0% (0 of 35) but the need for insulin therapy remained constant (9%, three of 35). 96 patients were re-exposed to asparaginase, including 59 after a severe asparaginase-associated pancreatitis (abdominal pain or pancreatic enzymes at least three times the ULN or both lasting longer than 72 h). 44 (46%) patients developed a second asparaginase-associated pancreatitis, 22 (52%) of 43 being severe. Risk of persisting need for insulin or abdominal pain after having had two versus one asparaginase-associated pancreatitis did not differ (three [7%] of 42 vs 28 [12%] of 233, p=0·51). Risk of a second asparaginase-associated pancreatitis was not associated with any baseline patient characteristics.

INTERPRETATION

Since the risk of a second asparaginase-associated pancreatitis was not associated with severity of the first asparaginase-associated pancreatitis and a second asparaginase-associated pancreatitis did not involve an increased risk of complications, asparaginase re-exposure should be determined mainly by the anticipated need for asparaginase for antileukaemic efficacy. A study of the genetic risk factors identifying patients in whom asparaginase exposure should be restricted is needed.

FUNDING

The Danish Childhood Cancer Foundation and The Danish Cancer Society (R150-A10181).

TropicALL study: Thromboprophylaxis in Children treated for Acute Lymphoblastic Leukemia with Low-molecular-weight heparin: a multicenter randomized controlled trial

Background

Venous thromboembolism (VTE) is a common and severe complication during treatment of acute lymphoblastic leukemia (ALL). An important cause is the intensive use of asparaginase. Prospective cohort studies in which prophylactic low-molecular-weight heparin (LMWH) was used to prevent VTE showed lower VTE risk than in historic control cohorts, with a negligible bleeding risk. However, the efficacy of thromboprophylaxis with LMWH during ALL treatment has never been investigated in a randomized design. Here, we present the protocol of a randomized controlled trial in which the efficacy and safety of thromboprophylaxis with high prophylactic dose LMWH versus no thromboprophylaxis will be assessed in children treated for primary ALL with asparaginase.

Methods/Design

Thromboprophylaxis in Children treated for Acute Lymphoblastic Leukemia with Low-molecular-weight heparin (TropicALL) is a multicenter, randomized controlled open-label trial conducted in the Netherlands. Patients between 1 and 19 years of age with primary ALL, who are treated within the Dutch Childhood Oncology Group (DCOG) ALL-11 or 12 study will be randomized to thromboprophylaxis with LMWH once daily, (dose of 85 IU/kg (intervention arm A)), or to no thromboprophylaxis (arm B, standard of care) during asparaginase courses of ALL treatment. Primary efficacy endpoint is symptomatic objectified VTE during ALL treatment; secondary efficacy endpoints are overall survival and the composite of symptomatic and asymptomatic objectified VTE. Primary safety endpoints are major bleeding, clinically relevant non-major bleeding and minor bleeding. A total of 324 patients will be included to obtain a relative risk reduction of 75% with a power of 80%, using a two-sided test with significance level α = 0.05.

Discussion

This trial will be the first to assess efficacy and safety of thromboprophylaxis with LMWH during asparaginase treatment for ALL in children in a randomized design.

Trail registration

Nederlands Trial Register NTR4707. Registered 30 July 2014.

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).

Allergic-like reactions to asparaginase: Atypical allergies without asparaginase inactivation

BACKGROUND

Asparaginase is an important component of pediatric acute lymphoblastic leukemia (ALL) therapy. Unfortunately, this treatment is hampered by hypersensitivity reactions. In general, allergies - regardless of severity - cause complete inactivation of the drug. However, we report atypical allergic reactions without inactivation of asparaginase, here called allergic-like reactions.

PROCEDURE

Patients with an allergic-like reaction, who were treated according to the Dutch Childhood Oncology Group ALL-11 or the CoALL 08-09 protocol, were described. The reactions were identified by continual measurement of asparaginase activity levels. Characteristics, including timing of occurrence, symptoms, grade, and the presence of antiasparaginase antibodies, were compared to those of real allergies.

RESULTS

Fourteen allergic-like reactions occurred in nine patients. Five reactions were to PEGasparaginase and nine to Erwinia asparaginase. Allergic-like reactions occurred relatively late after the start of infusion compared to real allergies. Antibodies were absent in all but one patient with an allergic-like reaction, while they were detected in all patients with a real allergy. Symptoms and grade did not differ between the groups. Asparaginase was continued with the same formulation in six patients of whom four finished treatment with adequate activity levels.

CONCLUSIONS

In conclusion, allergic-like reactions occur relatively late after the start of infusion and without antibodies. Despite these clinical differences, allergic-like reactions can only be distinguished from real allergies by continually measuring asparaginase activity levels. If clinically tolerated, formulations should not be switched in case of allergic-like reactions. Moreover, failure to recognize these reactions may lead to a less favorable prognosis if asparaginase therapy is terminated unnecessarily.

Asparaginase-associated toxicity in children with acute lymphoblastic leukemia

Asparaginase is an integral component of multiagent chemotherapy regimens for the treatment of children with acute lymphoblastic leukemia. Positive outcomes are seen in patients who are able to complete their entire prescribed course of asparaginase therapy. Toxicities associated with asparaginase use include hypersensitivity (clinical and subclinical), pancreatitis, thrombosis, encephalopathy, and liver dysfunction. Depending on the nature and severity of the toxicity, asparaginase therapy may be altered or discontinued in some patients. Clinical hypersensitivity is the most common asparaginase-associated toxicity requiring treatment discontinuation, occurring in up to 30% of patients receiving Escherichia coli-derived asparaginase. The ability to rapidly identify and manage asparaginase-associated toxicity will help ensure patients receive the maximal benefit from asparaginase therapy. This review will provide an overview of the common toxicities associated with asparaginase use and recommendations for treatment management.

Aggravated bone density decline following symptomatic osteonecrosis in children with acute lymphoblastic leukemia

Osteonecrosis and decline of bone density are serious side effects during and after treatment of childhood acute lymphoblastic leukemia. It is unknown whether osteonecrosis and low bone density occur together in the same patients, or whether these two osteogenic side-effects can mutually influence each other's development. Bone density and the incidence of symptomatic osteonecrosis were prospectively assessed in a national cohort of 466 patients with acute lymphoblastic leukemia (4-18 years of age) who were treated according to the dexamethasone-based Dutch Child Oncology Group-ALL9 protocol. Bone mineral density of the lumbar spine (BMDLS) (n=466) and of the total body (BMDTB) (n=106) was measured by dual X-ray absorptiometry. Bone density was expressed as age- and gender-matched standard deviation scores. Thirty patients (6.4%) suffered from symptomatic osteonecrosis. At baseline, BMDLS and BMDTB did not differ between patients who did or did not develop osteonecrosis. At cessation of treatment, patients with osteonecrosis had lower mean BMDLS and BMDTB than patients without osteonecrosis (respectively, with osteonecrosis: -2.16 versus without osteonecrosis: -1.21, P<0.01 and with osteonecrosis: -1.73 versus without osteonecrosis: -0.57, P<0.01). Multivariate linear models showed that patients with osteonecrosis had steeper BMDLS and BMDTB declines during follow-up than patients without osteonecrosis (interaction group time, P<0.01 and P<0.01). We conclude that bone density status at the diagnosis of acute lymphoblastic leukemia does not seem to influence the occurrence of symptomatic osteonecrosis. Bone density declines from the time that osteonecrosis is diagnosed; this suggests that the already existing decrease in bone density during acute lymphoblastic leukemia therapy is further aggravated by factors such as restriction of weight-bearing activities and destruction of bone architecture due to osteonecrosis. Osteonecrosis can, therefore, be considered a risk factor for low bone density in children with acute lymphoblastic leukemia.

The toxicity of very prolonged courses of PEGasparaginase or Erwinia asparaginase in relation to asparaginase activity, with a special focus on dyslipidemia

We prospectively studied the incidence and clinical course of hypertriglyceridemia and hypercholesterolemia during very prolonged use of asparaginase in relation to levels of asparaginase activity in children with acute lymphoblastic leukemia. We also evaluated the incidence of pancreatitis, thrombosis, hyperammonemia and central neurotoxicity and their association with asparaginase activity levels. Eighty-nine patients were treated according to the Dutch Childhood Oncology Group Acute Lymphoblastic Leukemia 10 medium-risk intensification protocol, which includes 15 doses of PEGasparaginase (2,500 IU/m(2)) over 30 weeks. Erwinia asparaginase (20,000 IU/m(2)) was administered when allergy to or silent inactivation of PEGasparaginase occurred. Triglyceride, cholesterol and ammonia levels increased rapidly in children treated with PEGasparaginase and remained temporarily elevated, but normalized after administration of the last asparaginase dose. Among the patients treated with PEGasparaginase, hypertriglyceridemia and hypercholesterolemia (grade 3/4) were found in 47% and 25%, respectively. The correlation between PEGasparaginase activity levels and triglyceride levels was strongest at week 5 (Spearman correlation coefficient = 0.36, P = 0.005). The triglyceride levels were higher in children ≥ 10 years old than in younger patients (<10 years old) after adjustment for type of asparaginase preparation: median 4.9 mmol/L versus 1.6 mmol/L (P<0.001). In patients receiving Erwinia asparaginase, triglyceride levels increased in the first weeks as well, but no grade 3/4 dyslipidemia was found. Hyperammonemia (grade 3/4) was only found in patients treated with Erwinia asparaginase (9%). Thrombosis occurred in 4.5%, pancreatitis in 7%, and central neurotoxicity in 9% of patients using either of the two agents; these toxicities were not related to levels of asparaginase activity or to triglyceride levels. In conclusion, severe dyslipidemia occurred frequently, but was temporary and was not associated with relevant clinical events and should not, therefore, be considered a reason for modifying asparaginase treatment. Dyslipidemia was the only toxicity related to levels of asparaginase activity.

Disturbed CXCR4/CXCL12 axis in paediatric precursor B-cell acute lymphoblastic leukaemia

Malignant cells infiltrating the bone marrow (BM) interfere with normal cellular behaviour of supporting cells, thereby creating a malignant niche. We found that CXCR4-receptor expression was increased in paediatric precursor B-cell acute lymphoblastic leukaemia (BCP-ALL) cells compared with normal mononuclear haematopoietic cells (P < 0·0001). Furthermore, high CXCR4-expression correlated with an unfavourable outcome in BCP-ALL (5-year cumulative incidence of relapse ± standard error: 38·4% ± 6·9% in CXCR4-high versus 12% ± 4·6% in CXCR4-low expressing cases, P < 0·0001). Interestingly, BM levels of the CXCR4-ligand (CXCL12) were 2·7-fold lower (P = 0·005) in diagnostic BCP-ALL samples compared with non-leukaemic controls. Induction chemotherapy restored CXCL12 levels to normal. Blocking the CXCR4-receptor with Plerixafor showed that the lower CXCL12 serum levels at diagnosis could not be explained by consumption by the leukaemic cells, nor did we observe an altered CXCL12-production capacity of BM-mesenchymal stromal cells (BM-MSC) at this time-point. We rather observed that a very high density of leukaemic cells negatively affected CXCL12-production by the BM-MSC while stimulating the secretion levels of granulocyte colony-stimulating factor (G-CSF). These results suggest that highly proliferative leukaemic cells are able to down-regulate secretion of cytokines involved in homing (CXCL12), while simultaneously up-regulating those involved in haematopoietic mobilization (G-CSF). Therefore, interference with the CXCR4/CXCL12 axis may be an effective way to mobilize BCP-ALL cells.

Bone mineral density at diagnosis determines fracture rate in children with acute lymphoblastic leukemia treated according to the DCOG-ALL9 protocol

PURPOSE

To elucidate incidence and risk factors of bone mineral density and fracture risk in children with Acute Lymphoblastic Leukemia (ALL).

METHODS

Prospectively, cumulative fracture incidence, calculated from diagnosis until one year after cessation of treatment, was assessed in 672 patients. This fracture incidence was compared between subgroups of treatment stratification and age subgroups (Log-Rank test). Serial measurements of bone mineral density of the lumbar spine (BMDLS) were performed in 399 ALL patients using dual energy X-ray absorptiometry. We evaluated risk factors for a low BMD (multivariate regression analysis). Osteoporosis was defined as a BMDLS≤-2 SDS combined with clinical significant fractures.

RESULTS

The 3-year cumulative fracture incidence was 17.8%. At diagnosis, mean BMDLS of ALL patients was lower than of healthy peers (mean BMDLS=-1.10 SDS, P<0.001), and remained lower during/after treatment (8months: BMDLS=-1.10 SDS, P<0.001; 24months: BMDLS=-1.27 SDS, P<0.001; 36months: BMDLS=-0.95 SDS, P<0.001). Younger age, lower weight and B-cell-immunophenotype were associated with a lower BMDLS at diagnosis. After correction for weight, height, gender and immunophenotype, stratification to the high risk (HR)-protocol arm and older age lead to a larger decline of BMDLS (HR group: β=-0.52, P<0.01; age: β=-0.16, P<0.001). Cumulative fracture incidences were not different between ALL risk groups and age groups. Patients with fractures had a lower BMDLS during treatment than those without fractures. Treatment-related bone loss was similar in patients with and without fractures (respectively: ΔBMDLS=-0.36 SDS and ΔBMDLS=-0.12 SDS; interaction group time, P=0.30). Twenty of the 399 patients (5%) met the criteria of osteoporosis.

CONCLUSION

Low values of BMDLS at diagnosis and during treatment, rather than the treatment-related decline of BMDLS, determine the increased fracture risk of 17.8% in children with ALL.

Cost-analysis of treatment of childhood acute lymphoblastic leukemia with asparaginase preparations: the impact of expensive chemotherapy

Asparaginase is an expensive drug, but important in childhood acute lymphoblastic leukemia. In order to compare costs of PEGasparaginase, Erwinia asparaginase and native E. coli asparaginase, we performed a cost-analysis in the Dutch Childhood Oncology Group ALL-10 medium-risk group intensification protocol. Treatment costs were calculated based on patient level data of 84 subjects, and were related to the occurrence of allergy to PEGasparaginase. Simultaneously, decision tree and sensitivity analyses were conducted. The total costs of the intensification course of 30 weeks were $57,893 in patients without PEGasparaginase allergy (n=64). The costs were significantly higher ($113,558) in case of allergy (n=20) necessitating a switch to Erwinia asparaginase. Simulated scenarios (decision tree analysis) using native E. coli asparaginase in intensification showed that the costs of PEGasparaginase were equal to those of native E. coli asparaginase. Also after sensitivity analyses, the costs for PEGasparaginase were equal to those of native E. coli asparaginase. Intensification treatment with native E. coli asparaginase, followed by a switch to PEGasparaginase, and subsequently to Erwinia asparaginase in case of allergy had similar overall costs compared to the treatment with PEGasparaginase as the first-line drug (followed by Erwinia asparaginase in the case of allergy). PEGasparaginase is preferred over native E. coli asparaginase, because it is administered less frequently, with less day care visits. PEGasparaginase is less immunogenic than native E. coli asparaginase and is not more expensive. Asparaginase costs are mainly determined by the percentage of patients who are allergic and require a switch to Erwinia asparaginase.

No evidence of increased asparagine levels in the bone marrow of patients with acute lymphoblastic leukemia during asparaginase therapy

BACKGROUND

Mesenchymal cells (MSCs) in bone marrow (BM) may produce asparagine and form protective niches for leukemic cells. In vitro, this led to high levels of asparagine and conferred asparaginase resistance to acute lymphoblastic leukemia (ALL) cells. The aim of this study was to investigate whether MSCs or other cells in BM indeed produce such significant amounts of asparagine in vivo as to result in clinical asparaginase resistance.

PROCEDURE

Twenty-six patients with newly diagnosed ALL were enrolled. All children received induction chemotherapy according to the Dutch Childhood Oncology Group (DCOG) ALL-10 protocol. Asparaginase was administered from days 12-33. Asparaginase, asparagine, aspartic acid, glutamine, and glutamic acid levels were measured in BM and blood at diagnosis, days 15, 33, and 79.

RESULTS

Median asparaginase trough levels were not significantly different at days 15 and 33. Only at diagnosis, asparagine level was significantly higher in BM than in blood (P = 0.001). Asparagine levels were all below the lower limit of quantification in BM and blood at days 15 and 33. However, aspartic acid level in BM was significantly higher than in blood (P < 0.001) at diagnosis, and also at days 15, 33, and 79.

CONCLUSIONS

We demonstrate higher aspartic acid levels in BM compared to blood; however, no increased asparagine levels were seen during induction therapy containing asparaginase in BM when compared to blood. Therefore, increased asparagine synthesis by MSCs is of relevance for resistance to asparaginase of leukemic cells in vitro, but it is questionable whether this leads to asparaginase resistance in childhood ALL patients.