Unexpected mortality from the use of E. coli L-asparaginase during remission induction therapy for childhood acute lymphoblastic leukemia: a report from the Taiwan Pediatric Oncology Group

Childhood acute lymphoblastic leukemia mercaptopurine intolerance is associated with NUDT15 variants

BACKGROUND

Mercaptopurine-induced neutropenia can interrupt chemotherapy and expose patients to infection during childhood acute lymphoblastic leukemia (ALL) treatment. Previously, six candidate gene variants associated with mercaptopurine intolerance were reported. Herein, we investigated the association between the mean tolerable dose of mercaptopurine and these genetic variants in Taiwanese patients.

METHODS

In total, 294 children with ALL were treated at the National Taiwan University Hospital from April 1997 to December 2017. Germline variants were analyzed for NUDT15, SUCLA2, TPMT, ITPA, PACSIN2, and MRP4. Mean daily tolerable doses of mercaptopurine in the continuation phase of treatment were correlated with these genetic variants.

RESULTS

Mercaptopurine intolerance was significantly associated with polymorphisms in NUDT15 (P value < 0.0001). Patients with SUCLA2 variants received lower mercaptopurine doses (P value = 0.0119). The mean mercaptopurine doses did not differ among patients with TPMT, ITPA, MRP4, and PACSIN2 polymorphisms (P value = 0.9461, 0.5818, and 0.7951, respectively). After multivariable linear regression analysis, only NUDT15 variants retained their clinically significant correlation with mercaptopurine intolerance (P value < 0.0001).

CONCLUSION

In this cohort, the major genetic determinant of mercaptopurine intolerance was NUDT15 in Taiwanese patients.

IMPACT

NUDT15 causes mercaptopurine intolerance in children with ALL. The NUDT15 variant is a stronger predictor of mercaptopurine intolerance than TPMT in a Taiwanese cohort. This finding is similar with studies performed on Asian populations rather than Caucasians. Pre-emptive genotyping of the patients' NUDT15 before administering mercaptopurine may be more helpful than genotyping TPMT in Asians.

Triple Intrathecal Therapy Alone With Omission of Cranial Radiation in Children With Acute Lymphoblastic Leukemia

Purpose

To eliminate the toxicities and sequelae of cranial irradiation (CrRT) and to minimize the adverse impact of traumatic lumbar puncture (TLP) with blasts, a prospective study of a modified CNS-directed therapy was conducted in children with acute lymphoblastic leukemia (ALL).

Patients and Methods

Since June 1999, children with newly diagnosed ALL have been treated with triple intrathecal therapy (TIT) alone without CrRT. The first TIT was delayed until the disappearance of blasts from peripheral blood (PB) for up to 10 days of multidrug induction, and CrRT was omitted in all patients. If PB blasts persisted on treatment day 10 (d10), the TIT was then performed.

Results

Of a total of 156 patients, 152 were eligible. Seventeen patients did not have PB blasts at diagnosis. Three fourths of the remaining patients achieved complete clearance of PB blasts by d10. Only hyperleukocytosis at diagnosis showed a significantly lower clearance rate. Six standard-risk patients were upgraded to high risk because of detectable PB blasts on d10. TLPs were encountered in four patients (2.6%), but none were contaminated with lymphoblasts. Neither CNS-2 (less than 5 WBCs/μL with blasts in a nontraumatic sample) nor CNS-3 (≥ 5 WBCs/μL with blasts in a nontraumatic sample or the presence of cranial nerve palsy) was present. The 5-year event-free survival and overall survival rates ± SE were 84.2% ± 3.0% and 90.6% ± 2.4%, respectively. No isolated CNS relapse occurred, but two patients experienced combined CNS relapses. The 7-year cumulative risk of any CNS relapse was 1.4% ± 1.0%.

Conclusion

Delaying first TIT until circulating blasts have cleared may improve CNS control in children with newly diagnosed ALL and preclude the need for CrRT.

Cloning, expression, purification and characterisation of Erwinia carotovora L-asparaginase in Escherichia coli

Background:

For the past 30 years, bacterial L-asparaginases have been used as therapeutic agents in the treatment of acute childhood lymphoblastic leukemia. It is found in a variety of organisms such as microbes, plants and mammals. Their intrinsic low-rate glutaminase activity, however, causes serious side-effects, including neurotoxicity, hepatitis, coagulopathy and other dysfunctions. Erwinia carotovora asparaginase shows decreased glutaminase activity, so it is believed to have fewer side-effects in leukemia therapy. Our aim was to clone, express, purify and characterize E. carotovora asparaginase.

Materials and Methods:

L-asparaginase from E. carotovora NCYC 1526 (ErA) was cloned and expressed in Escherichia coli strain BL21 (DE3). The enzyme was purified to homogeneity by affinity chromatography. Various conditions were tested to maximize the production of recombinant asparaginase in E. coli.

Results:

A new L. asparaginase from E. carotovora NCYC 1526 (ErA) was successfully cloned, expressed and purified in E. coli BL21 (DE3). The specific activity of the enzyme was 430 IU/mg.

Conclusion:

The results of the present work form the basis for a new engineered form of ErA for future therapeutic use, which could be extended with crystallographic studies.

IKZF1 deletions predict a poor prognosis in children with B-cell progenitor acute lymphoblastic leukemia: a multicenter analysis in Taiwan

Despite current risk-directed therapy, approximately 15-20% of pediatric patients with acute lymphoblastic leukemia (ALL) have relapses. Recent genome-wide analyses have identified that an alteration of IKZF1 is associated with very poor outcomes in B-cell progenitor ALL. In this study, we determined the prognostic significance of IKZF1 deletions in patients with childhood ALL. This study analyzed 242 pediatric B-cell progenitor ALL patients in Taiwan. We developed a simple yet sensitive multiplex quantitative PCR coupled with capillary electrophoresis to accurately determine the allele dose of IKZF1, and high resolution melting was used for mutation screening for all coding exons of IKZF1. Twenty-six (10.7%) pediatric B-cell progenitor ALL patients were found to harbor these deletions. Most of the deletions were broader deletions that encompassed exon 3 to exon 6, consistent with previous reports. Genomic sequencing of IKZF1 was carried out in all cases and no point mutations were identified. Patients with IKZF1 deletions had inferior event-free survival (P < 0.001), and overall survival (P = 0.0016). The association between IKZF1 deletions and event-free survival was independent of age, leukocyte count at presentation, and cytogenetic subtype by multivariate Cox analysis (P = 0.003, hazard ratio = 2.45). This study indicates that detection of IKZF1 deletions upon diagnosis of B-cell progenitor ALL may help to identify patients at risk of treatment failure. IKZF1 deletions could be incorporated as a new high-risk prognostic factor in future treatment protocols. To the best of our knowledge, this is the first study to examine the poor prognosis of IKZF1 deletions in an Asian population.

L-asparaginase treatment in acute lymphoblastic leukemia: a focus on Erwinia asparaginase

Asparaginases are a cornerstone of treatment protocols for acute lymphoblastic leukemia (ALL) and are used for remission induction and intensification treatment in all pediatric regimens and in the majority of adult treatment protocols. Extensive clinical data have shown that intensive asparaginase treatment improves clinical outcomes in childhood ALL. Three asparaginase preparations are available: the native asparaginase derived from Escherichia coli (E. coli asparaginase), a pegylated form of this enzyme (PEG-asparaginase), and a product isolated from Erwinia chrysanthemi, ie, Erwinia asparaginase. Clinical hypersensitivity reactions and silent inactivation due to antibodies against E. coli asparaginase, lead to inactivation of E. coli asparaginase in up to 60% of cases. Current treatment protocols include E. coli asparaginase or PEG-asparaginase for first-line treatment of ALL. Typically, patients exhibiting sensitivity to one formulation of asparaginase are switched to another to ensure they receive the most efficacious treatment regimen possible. Erwinia asparaginase is used as a second- or third-line treatment in European and US protocols. Despite the universal inclusion of asparaginase in such treatment protocols, debate on the optimal formulation and dosage of these agents continues. This article provides an overview of available evidence for optimal use of Erwinia asparaginase in the treatment of ALL.

Expression and prognostic significance of the apoptotic genes BCL2L13, Livin, and CASP8AP2 in childhood acute lymphoblastic leukemia

Improved treatment of childhood acute lymphoblastic leukemia (ALL) depends on the identification of new molecular markers that are able to predict treatment response and clinical outcome. The development of impaired apoptosis in leukemic cells is one factor that may influence their response to treatment. We investigated the expression of three apoptosis related genes, BCL2L13, CASP8AP2, and Livin, as well as their prognostic significance, in a retrospective study of 90 pediatric ALL patients diagnosed between 1996 and 2007 in Taiwan. Univariant analysis revealed that high expression of BCL2L13 was associated with inferior event-free survival and overall survival (p<0.001 and 0.005, respectively). Multivariate analysis for EFS and OS demonstrated that high expression of BCL2L13 was an independent prognostic factor for childhood ALL in this ethnic group.

Pharmacogenomic variations in treatment protocols for childhood acute lymphoblastic leukemia

OBJECTIVES

This retrospective study evaluates the role of pharmacogenomic determinants in the treatment of childhood acute lymphoblastic leukemia (ALL) in the Taiwanese population.

METHODS

A total of 105 childhood ALL patients received combined chemotherapy of different intensities based on risk-directed Taiwan Pediatric Oncology Group (TPOG)-ALL-93 protocols. Seventeen genetic polymorphisms in 13 pharmacogenomic targets were analyzed by PCR-based restriction fragment length polymorphism (RFLP) and sequence-specific oligonucleotide (SSO) probe hybridization. Pharmacogenomic polymorphisms were correlated with event-free survival (EFS) of patients, with confounding effects adjusted by multivariate regression.

RESULTS

Three polymorphic alleles in the multi-drug resistance 1 (MDR1) ABCB1 gene, and homozygotic MDR1 2677GG, 3435CC, and 2677G-3435C genotypes were highly associated with a significant reduction in EFS in those patients treated by the standard risk (SR) protocol (TPOG-ALL-93-SR). The hazard ratios were 6.8 (p = 0.01), 21.7 (p = 0.009), and 6.8 (p = 0.01), respectively.

CONCLUSIONS

Independent pharmacogenomic determinants associated with treatment outcome were identified in subsets of Taiwanese ALL patients.

Risk-adapted treatment of pediatric acute lymphoblastic leukemia

Optimal use of antileukemic agents and stringent application of risk-directed therapy in clinical trials have resulted in steady improvement in the outcome of children with acute lymphoblastic leukemia, with current cure rates exceeding 80% in developed countries. The intensity of treatment varies substantially among subsets of patients, as therapy is designed to reduce acute and long-term toxicity in low-risk groups while improving outcomes in poor risk groups by treatment intensification. Recent advances in genome-wide screening techniques, pharmacogenomic studies, and development of molecular therapeutics are ushering in an era of more refined personalized therapy.

Long-term results of Taiwan Pediatric Oncology Group studies 1997 and 2002 for childhood acute lymphoblastic leukemia

The long-term outcome of 1390 children with acute lymphoblastic leukemia (ALL), treated in two successive clinical trials (Taiwan Pediatric Oncology Group (TPOG)-ALL-97 and TPOG-ALL-2002) between 1997 and 2007, is reported. The event-free survival improved significantly (P=0.0004) over this period, 69.3+/-1.9% in 1997-2001 to 77.4+/-1.7% in 2002-2007. A randomized trial in TPOG-97 testing L-asparaginase versus epidoxorubicin in combination with vincristine and prednisolone for remission induction in standard-risk (SR; low-risk) patients yielded similar outcomes. Another randomized trial, in TPOG-2002, showed that for SR patients, two reinduction courses did not improve long-term outcome over one course. Decreasing use of prophylactic cranial irradiation in the period 1997-2008 was not associated with increased rates of CNS relapse, prompting complete omission of prophylactic cranial irradiation from TPOG protocols, beginning in 2009. Decreased use of etoposide and cranial irradiation likely contributed to the low incidence of second cancers. High-risk B-lineage ALL, T-cell, CD10 negativity, t(9;22), infant, and higher leukocyte count were consistently adverse factors, whereas hyperdiploidy >50 was a consistently favorable factor. Higher leukocyte count and t(9;22) retained prognostic significance in both TPOG-97 and TPOG-2002 by multivariate analysis. Although long-term outcome in TPOG clinical trials is comparable with results being reported worldwide, the persistent strength of certain prognostic variables and the lower frequencies of favorable outcome predictors, such as ETV6-RUNX1 and hyperdiploidy >50, in Taiwanese children warrant renewed effort to cure a higher proportion of patients while preserving their quality of life.

Diabetic ketoacidosis during therapy for pediatric acute lymphoblastic leukemia

BACKGROUND

Hyperglycemia is common during therapy for acute lymphoblastic leukemia (ALL), but diabetic ketoacidosis (DKA) occurs rarely. Morbidity due to DKA in children with ALL has not been systematically studied.

PROCEDURES

We reviewed risk factors and clinical consequences of DKA in patients undergoing therapy for ALL at SJCRH between 1991 and 2006.

RESULTS

DKA occurred in 6 of 797 evaluable patients. Only older age at diagnosis of ALL was a risk factor for DKA. Four of six patients with DKA as compared to 232 of the other 791 patients were older than 10 years (P = 0.03). Race, sex, body mass index, leukemia immunophenotype, ALL risk category, white blood cell count at diagnosis, and treatment protocol were not associated with DKA. All patients were managed with intravenous fluids, dietary modification, and short-term use of insulin. Patients were hospitalized for 4-12 days, with a median ICU stay of 1 day. In two patients, correction of hyperglycemia was too rapid, and two others experienced hypoglycemia due to insulin therapy. There were no permanent complications of DKA or its treatment. No patient required long-term insulin use. No patient had recurrent DKA; only one of the six patients had a subsequent hyperglycemia episode. All six patients are alive in remission 6-13 years after diagnosis.

CONCLUSIONS

Patients with hyperglycemia during treatment for ALL should be screened for clinical evidence of DKA, which may require more intensive supportive care than those without ketoacidosis. The occurrence of DKA should not lead to alteration of ALL treatment.

Triple intrathecal therapy without cranial irradiation for central nervous system preventive therapy in childhood acute lymphoblastic leukemia

BACKGROUND

To evaluate the treatment results of central nervous system preventive therapy (CNSP) with triple intrathecal therapy (TIT) alone in children with acute lymphoblastic leukemia (ALL).

METHODS

We retrospectively studied a cohort of 59 patients with median follow-up time 50.6 months (range: 27-80 months) at a single institution in Taiwan. Patients with ALL were classified in risk groups at diagnosis. TPOG-ALL-93 protocols and TPOG-ALL-2002 protocols were used. Both protocols were for multicenter studies in Taiwan and contained protocols for standard-risk (SR), high-risk (HR), and very-high-risk (VHR) patients. In this study, we used TIT alone for CNSP. In all ALL patients, methotrexate, hydrocortisone, and cytarabine were given at age-dependent doses.

RESULTS

As of October 2006, patients had a 3-year event-free survival and an overall survival 89.4 +/- 4.1% (S.E.) and 93.1 +/- 3.3%, respectively. Under TIT no patients had complications such as seizure, encephalitis, or infection, and no morbidities like those caused by cranial irradiation. In this study, we used TIT alone for CNSP and had no CNS relapse.

CONCLUSIONS

In the context of effective systemic therapy, TIT alone appears to be effective CNSP for most patients with ALL.

Death during induction therapy and first remission of acute leukemia in childhood

BACKGROUND

Despite improvements in supportive care, death due to treatment toxicity remains a significant problem for children treated for acute leukemia.

METHODS

To determine the causes of and risk factors for death unrelated to refractory leukemia, to disease recurrence, or to second malignancy, the authors reviewed the records of 1011 patients with acute lymphoblastic leukemia (ALL) and 260 patients with acute myeloid leukemia (AML) treated between 1984 and 1999 and between 1983 and 2002, respectively, at St. Jude Children's Research Hospital (Memphis, TN). Data for patients who underwent stem cell transplantation were censored at the time of transplantation.

RESULTS

For patients with ALL, the estimated 10-year cumulative incidence of death was 2.9% +/- 5.3%. Age was the only predictor of death. Patients with ALL 1-9 years old had a significantly lower risk of death than did younger or older patients (P = 0.002). For patients with AML, the estimated 5-year cumulative incidence of death was 7.6% +/- 1.9%. Increasing age and increasing leukocyte count were significantly associated with increased risk of death. For patients with ALL and with AML, the incidence of death remained relatively constant during the time periods studied. Infection was the most common cause of death.

CONCLUSIONS

In the current study, the authors determined that children > or = 10 years of age are at increased risk of death during therapy for ALL and AML.

Role of pharmacogenomics and pharmacodynamics in the treatment of acute lymphoblastic leukaemia

Pharmacodynamic studies have been used to establish the relationships between the administered dosage and the concentration of drugs and metabolites in the blood or tissues and that between these concentrations and pharmacological effects. Polymorphisms in the genes that encode drug-metabolizing enzymes, drug transporters and drug targets can affect a person's response to therapy and may affect the development of de novo or therapy-related leukaemias. The burgeoning field of pharmacogenomics elucidates inherited differences in drug metabolism and treatment response. Increasingly, pharmacodynamic and pharmacogenomic studies are being used to individualize therapy to enhance efficacy and reduce toxicity.

Serious neutropenia in ALL patients treated with L-asparaginase may be avoided by therapeutic monitoring of the enzyme activity in the circulation

The antineoplastic enzyme L-asparaginase is commonly used for the induction of remission in acute lymphoblastic leukemia (ALL). L-Asparagine is an essential amino acid for many lymphoid tumor cells and L-asparaginase catalyzes its conversion to L-aspartic acid and ammonia. The dosage of this highly toxic drug is individualized based on the body surface area of the patient, but monitoring of L-asparaginase activity during the L-asparaginase therapy is not commonly used. We measured L-asparaginase activity in the serum of ten children (aged 3-13 y) with ALL (ALL NOPHO-92 standard or intermediate risk groups) during their L-asparaginase therapy. L-asparaginase was given 30,000 IU/m2 IM during days 37-46 of the induction therapy and no other chemotherapeutic drug except for prednisone was given at the same time. We observed that this dosage schedule resulted in almost 6-fold differences in the serum activity of L-asparaginase between the patients. There was also a relationship between the area under the L-asparaginase activity-time curve (AUC) and even peak L-asparaginase activity in serum during the enzyme therapy and neutropenia after the therapy in the patients: the higher the AUC or peak value was, the more severe was the neutropenia in the patients after treatment. Monitoring L-asparaginase in serum could be useful in optimization of the therapy with this toxic drug.

Multiplex RT-PCR assay for the detection of major fusion transcripts in Taiwanese children with B-lineage acute lymphoblastic leukemia

BACKGROUND

The classification of B-lineage acute lymphoblastic leukemia (ALL) by specific chromosomal translocations may have prognostic implications. Reverse transcriptase-polymerase chain reaction (RT-PCR) assay is a useful tool for the detection of fusion transcript resulting from specific chromosomal translocation of the leukemic cells. In general, fusion transcripts are determined individually, a process which is labor intensive in order to detect all major fusion transcripts.

PROCEDURE

We use a multiplex RT-PCR assay to detect both the CML- and ALL-type BCR-ABL transcripts of the t(9;22), all described variants of the E2A-PBX1 transcripts of t(1;19), the MLL-AF4 transcripts of t(4;11), and all described variants of TEL-AML1 (also termed ETV6-CBFA2) of the cryptic t(12;21) in 165 leukemic samples at diagnosis.

RESULTS

The study yielded a completely concordant result with those obtained by the individual RT-PCR assay. In this cohort of Taiwan children, the relative frequencies of the four translocations of B-lineage ALL were as following: 6% with ALL-type t(9;22)/BCR-ABL, 7% t(1;19)/E2A-PBX1, 3% t(4;11)/MLL-AF4, and 18% t(12;21)/TEL-AML1, comparable to those in the Western countries.

CONCLUSION

Multiplex RT-PCR assay is an efficient, sensitive, accurate, and cost-effective diagnostic tool, which will likely improve our ability in accurately and rapidly risk-stratifying children with ALL.

Childhood acute lymphoblastic leukaemia--current status and future perspectives

The current cure rate of 80% in childhood acute lymphoblastic leukaemia attests to the effectiveness of risk-directed therapy developed through well-designed clinical trials. In the past decade there have been remarkable advances in the definition of the molecular abnormalities involved in leukaemogenesis and drug resistance. These advances have led to the development of promising new therapeutic strategies, including agents targeted to the molecular lesions that cause leukaemia. The importance of host pharmacogenetics has also been recognised. Thus, genetic polymorphisms of certain enzymes have been linked with host susceptibility to the development of de novo leukaemia or therapy-related second cancers. Furthermore, recognition of inherited differences in the metabolism of antileukaemic agents has provided rational selection criteria for optimal drug dosages and scheduling. Treatment response assessed by measurements of submicroscopic leukaemia (minimal residual disease) has emerged as a powerful and independent prognostic indicator for gauging the intensity of therapy. Ultimately, treatment based on biological features of leukaemic cells, host genetics, and the amount of residual disease should improve cure rates further.

Acute lymphoblastic leukemia in children

As the overall long-term event-free survival rate in children with acute lymphoblastic leukemia approaches 80%, emphasis is being placed on risk-directed therapy so that patients are neither overtreated nor undertreated. It has become apparent that a risk assignment system based on primary genetic abnormalities is inadequate by itself. For example, leukemias with the MLL-AF4 or BCR-ABL fusion gene are, in fact, heterogeneous diseases. Many require allogeneic hematopoietic stem-cell transplantation; some, if the patient is of favorable age and has a low presenting leukocyte count, can be cured with chemotherapy alone. Measurement of early responses to therapy and extent of minimal residual disease can greatly improve the accuracy of risk assessment. Consideration of the variable effects of therapy on the prognostic significance of specific genetic abnormalities is also important. Therefore, TEL-AML1 fusion confers a favorable prognosis in some protocols of chemotherapy but not in others. Studies to identify genetic polymorphisms with pharmacokinetic and pharmacodynamic significance promise to guide further refinement of treatment strategies. This will allow maximization of anticancer effects without induction of unacceptable toxicity in individual patients.