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.

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 1st (n=11), early 1st (n=15), ≥2nd 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.

Randomized trial comparing liposomal daunorubicin with idarubicin as induction for pediatric acute myeloid leukemia: results from Study AML-BFM 2004.

Outcomes of patients with acute myeloid leukemia (AML) improve significantly by intensification of induction. To further intensify anthracycline dosage without increasing cardiotoxicity, we compared potentially less cardiotoxic liposomal daunorubicin (L-DNR) to idarubicin at a higher-than-equivalent dose (80 vs 12 mg/m(2) per day for 3 days) during induction. In the multicenter therapy-optimization trial AML-BFM 2004, 521 of 611 pediatric patients (85%) were randomly assigned to L-DNR or idarubicin induction. Five-year results in both treatment arms were similar (overall survival 76% ± 3% [L-DNR] vs 75% ± 3% [idarubicin], Plogrank = .65; event-free survival [EFS] 59% ± 3% vs 53% ± 3%, Plogrank = .25; cumulative incidence of relapse 29% ± 3% vs 31% ± 3%, P(Gray) = .75), as were EFS results for standard (72% ± 5% vs 68% ± 5%, Plogrank = .47) and high-risk (51% ± 4% vs 46% ± 4%, Plogrank = .45) patients. L-DNR resulted in significantly better probability of EFS in patients with t(8;21). Overall, treatment-related mortality was lower with L-DNR than idarubicin (2/257 vs 10/264 patients, P = .04). Grade 3/4 cardiotoxicity was rare after induction (4 L-DNR vs 5 idarubicin). Only 1 L-DNR and 3 idarubicin patients presented with subclinical or mild cardiomyopathy during follow-up. In conclusion, at the given dose, L-DNR has overall antileukemic activity comparable to idarubicin, promises to be more active in subgroups, and causes less treatment-related mortality. This trial was registered at www.clinicaltrials.gov as #NCT00111345.

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.

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).

An unusual case of high hyperdiploid childhood ALL with cryptic BCR/ABL1 rearrangement.

BACKGROUND: Both high hyperdiploidy (HeH) and the translocation t(9;22)(q34;q11) are recurrent abnormalities in childhood B-cell acute lymphoblastic leukemia (ALL) and both are used in current classification to define different genetic and prognostic subtypes of the disease. The coexistence of these two primary genetic aberrations within the same clone is very rare in children with ALL. Here we report a new case of a 17-year-old girl with newly diagnosed ALL and uncommon cytogenetic and clinical finding combining high hyperdiploidy and a cryptic BCR/ABL1 fusion and an inherited Charcot-Marie-Tooth neuropathy detected during the induction treatment. RESULTS: High hyperdiploid karyotype 51,XX,+X,+4,+14,+17,+21 without apparent structural aberrations was detected by conventional cytogenetic analysis and multicolor FISH. A cryptic BCR/ABL1 fusion, which was caused by the insertion of part of the ABL1 gene into the 22q11 region, was proved in HeH clone by FISH, RT-PCR and CGH-SNP array. In addition, an abnormal FISH pattern previously described as the deletion of the 3'BCR region in some BCR/ABL1 positive cases was not proved in our patient. CONCLUSION: A novel case of extremely rare childhood ALL, characterized by HeH and a cryptic BCR/ABL1 fusion, is presented and to the best of our knowledge described for the first time. The insertion of ABL1 into the BCR region in malignant cells is supposed. Clearly, further studies are needed to determine the genetic consequences and prognostic implications of these unusual cases.