Risk-adapted treatment of pediatric acute lymphoblastic leukemia

St. Jude Total Therapy studies from I to XVII for childhood acute lymphoblastic leukemia: a brief review

The therapy design of childhood acute lymphoblastic leukemia (ALL) has evolved over the past 60 years. The St. Jude Children's Research Hospital has developed 17 treatment protocols from 1962 to 2017, aiming to have the most effective and least toxic treatment form. This review summarizes each protocol's objectives, inclusion criteria, treatment phases, pharmacological agents, irradiation therapy, response criteria, risk stratification, type of relapse, and overall survival. The enhancement and successful application of preventive therapy for ALL and following a risk-stratified approach have progressively improved the cure rate of childhood ALL, with relatively few adverse sequelae. Moreover, St. Jude's scientific theme serves as a reminder of the principal factor of research directed to a catastrophic disease such as ALL.

Low Prevalence of ETV6::RUNX1 Fusion Gene in a Hispanic Population

ETV6::RUNX1 is a genetic rearrangement of good prognosis in children with acute lymphoblastic leukemia (ALL). In Mexico, its prevalence is low in comparison with Caucasian populations. We developed a novel TaqMan one-step RT-qPCR approach to assess the prevalence of four genetic rearrangements in a cohort of Hispanic children with ALL from Mexico City. The prevalence of common fusion gene transcripts was as follows: TCF3::PBX1 7.7%; BCR::ABL1p 190 3.3%; and KMT2A::AFF1 2.8%, and ETV6::RUNX1was observed with low prevalence (10.5%) in comparison to that reported for developed countries. This is consistent with previous findings on Mexican children with ALL and similar to those reported on children from Hispanic populations. The confirmation of a low prevalence of ETV6::RUNX1 in children of a Hispanic origin represents an advancement in the description of genetic factors of ALL in these populations.

How I investigate minimal residual disease in acute lymphoblastic leukemia

Minimal Residual Disease (MRD) is the most important independent prognostic factor in acute lymphoblastic leukemia (ALL) and refers to the deep level of measurable disease in cases with complete remission by conventional pathologic analysis, especially by cytomorphology. MRD can be detected by multiparametric flow cytometry, molecular approaches such as quantitative polymerase chain reaction for immunoglobulin and T-cell receptor (IG/TR) gene rearrangements or fusion genes transcript, and high-throughput sequencing for IG/TR. Despite the proven clinical usefulness in detecting MRD, these methods have differences in sensitivity, specificity, applicability, turnaround time and cost. Knowing and understanding these differences, as well as the principles and limitations of each technology, is essential to laboratory standardization and correct interpretation of MRD results in line with treatment time points, therapeutic settings, and clinical trials. Here, we review the methodological approaches to measure MRD in ALL and discuss the advantages and limitations of the most commonly used techniques.

Examining treatment responses of diagnostic marrow in murine xenografts to predict relapse in children with acute lymphoblastic leukaemia

BACKGROUND

While current chemotherapy has increased cure rates for children with acute lymphoblastic leukaemia (ALL), the largest number of relapsing patients are still stratified as medium risk (MR) at diagnosis (50-60%). This highlights an opportunity to develop improved relapse-prediction models for MR patients. We hypothesised that bone marrow from MR patients who eventually relapsed would regrow faster in a patient-derived xenograft (PDX) model after induction chemotherapy than samples from patients in long-term remission.

METHODS

Diagnostic bone marrow aspirates from 30 paediatric MR-ALL patients (19 who relapsed, 11 who experienced remission) were inoculated into immune-deficient (NSG) mice and subsequently treated with either control or an induction-type regimen of vincristine, dexamethasone, and L-asparaginase (VXL). Engraftment was monitored by enumeration of the proportion of human CD45⁺ cells (%huCD45⁺) in the murine peripheral blood, and events were defined a priori as the time to reach 1% huCD45⁺, 25% huCD45⁺ (TT25%) or clinical manifestations of leukaemia (TTL).

RESULTS

The TT25% value significantly predicted MR patient relapse. Mutational profiles of PDXs matched their tumours of origin, with a clonal shift towards relapse observed in one set of VXL-treated PDXs.

CONCLUSIONS

In conclusion, establishing PDXs at diagnosis and subsequently applying chemotherapy has the potential to improve relapse prediction in paediatric MR-ALL.

A review of current induction strategies and emerging prognostic factors in the management of children and adolescents with acute lymphoblastic leukemia

INTRODUCTION

Acute lymphoblastic leukemia is the most frequent hematologic malignancy in children. Almost 95% of children potentially achieve a complete remission after the induction treatment, but over the last years, new insights in the genomic disease profile and in minimal residual disease detection techniques have led to an improvement in the prognostic stratification, identifying selected patients' subgroups with peculiar therapeutic needs.

AREAS COVERED

According to a comprehensive search of peer-review literature performed in Pubmed, in this review we summarize the recent evidences on the induction treatment strategies comprised in the children acute lymphoblastic leukemia scenario, focusing on the role of key drugs such as corticosteroids and asparaginase and discussing the crucial significance of the genomic characterization at baseline which may drive the proper induction treatment choice.

EXPERT OPINION

Current induction strategies already produce durable remissions in a significant proportion of standard-risk children with acute lymphoblastic leukemia. A broader knowledge of the biologic features related to acute lymphoblastic leukemia subtypes with worse prognosis, and an optimization of targeted drugs now available, might lead to the achievement of long-term molecular remissions in this setting.

New biomarkers in non-Hodgkin lymphoma and acute leukemias

Biomarkers play a critical role in the medical care of patients with cancer, including in early detection of the disease, diagnostic accuracy, risk stratification, treatment, and follow-up. Biomarkers in hematological malignancies can support the redefinition of the diagnosis and adjustments in the treatment plan. Biomarkers can be classified into 4 categories: (1) protein antigens, (2) cytogenetic abnormalities, (3) genetic polymorphisms, and (4) gene expression. Efforts in genomics, proteomics, and metabolomics to observe new biomarkers that contribute to the development of clinical medicine with greater precision in the strategies that improve prevention, diagnosis, and treatment of patients with malignant hematological disease. New biomarkers should accomplish several issues such as the biological plausibility, methodology used, analytical validation, intellectual property registry, and legal framework of application. This knowledge should be transferred to health professionals who can carry out the process of its implementation in clinical practice.

Long-term effects on growth, development, and metabolism of ALL treatment in childhood

INTRODUCTION

One aim of the long-term care in survivors from acute lymphoblastic leukemia (ALL) during childhood is to avoid or limit complications caused by aggressive therapeutic strategies.

AREAS COVERED

ALL survivors are a heterogeneous group according to therapeutic protocols. In the last decades, cranial radiotherapy (cRT) has been largely replaced by intrathecal chemotherapy (CT) with a reduction of endocrine sequelae. Published studies are generally difficult to be interpreted because patients were treated according to different risk-adapted protocols and results are conflicting. We perform this review on endocrine long-term effects in childhood ALL survivors focusing on studies published in the last decades. Articles were selected using the following terms (Mesh terms): 'acute lymphoblastic leukemia' AND 'survivors' AND 'childhood' AND 'growth/puberty/fertility/obesity/metabolic syndrome/bone'.

EXPERT COMMENTARY

Most childhood ALL survivors treated with CT alone attain normal height and have adequate pubertal development. Despite recent protocols improvements, ALL survivors still develop long-term metabolic complications (overweight, obesity, and cardiovascular disease) especially the female gender and patients with an increased body mass index (BMI) at diagnosis. The aim of this review is to describe the state of the art on these topics. We should be able to anticipate, prevent, and treat endocrine long-term morbidities through a well-established follow-up strategy.

Potent efficacy of combined PI3K/mTOR and JAK or ABL inhibition in murine xenograft models of Ph-like acute lymphoblastic leukemia

Philadelphia chromosome (Ph)-like B-cell acute lymphoblastic leukemia (Ph-like ALL) is associated with activated JAK/STAT, Abelson kinase (ABL), and/or phosphatidylinositol 3-kinase (PI3K) signaling and poor clinical outcomes. PI3K pathway signaling inhibitors have been minimally investigated in Ph-like ALL. We hypothesized that targeted inhibition of PI3Kα, PI3Kδ, PI3K/mTOR, or target of rapamycin complex 1/2 (TORC1/TORC2) would decrease leukemia proliferation and abrogate aberrant kinase signaling and that combined PI3K pathway and JAK inhibition or PI3K pathway and SRC/ABL inhibition would have superior efficacy compared to inhibitor monotherapy. We treated 10 childhood ALL patient-derived xenograft models harboring various Ph-like genomic alterations with 4 discrete PI3K pathway protein inhibitors and observed marked leukemia reduction and in vivo signaling inhibition in all models. Treatment with dual PI3K/mTOR inhibitor gedatolisib resulted in near eradication of ALL in cytokine receptor-like factor 2 (CRLF2)/JAK-mutant models with mean 92.2% (range, 86.0%-99.4%) reduction vs vehicle controls (P < .0001) and in prolonged animal survival. Gedatolisib also inhibited ALL proliferation in ABL/platelet-derived growth factor receptor (PDGFR)-mutant models with mean 66.9% (range, 42.0%-87.6%) reduction vs vehicle (P < .0001). Combined gedatolisib and ruxolitinib treatment of CRLF2/JAK-mutant models more effectively inhibited ALL proliferation than either inhibitor alone (P < .001) and further enhanced survival. Similarly, superior efficacy of combined gedatolisib and dasatinib was observed in ABL/PDGFR-mutant models (P < .001). Overall, PI3K/mTOR inhibition potently decreased ALL burden in vivo; antileukemia activity was further enhanced with combination inhibitor therapy. Clinical trials testing combinations of kinase inhibitors in Ph-like ALL patients are indicated.

Prophylactic Trimethoprim-Sulfamethoxazole Does Not Affect Pharmacokinetics or Pharmacodynamics of Methotrexate

Trimethoprim-sulfamethoxazole (TMP/SMX) is used as prophylaxis against Pneumocystis jiroveci during chemotherapy. Many groups recommend withholding TMP/SMX during high-dose methotrexate (HDMTX) for concerns that it will delay methotrexate clearance. We compared methotrexate exposure following HDMTX (NCT00549848) in 424 patients including 783 courses that were given concurrently and 602 courses that were not given concurrently with TMP/SMX. Among 176 patients (555 courses) on the low-risk arm (HDMTX=2.5 g/m/24 h), there was no difference in clearance (110.7 [1.8%] vs. 108.2 [0.9%] mL/min/m, P=0.3) nor in 42 hour methotrexate concentration (0.37 [5.1%] vs. 0.40 (5.0%) μM, P=0.23). Among 248 patients (830 courses) on the standard/high-risk arm (HDMTX ~5 g/m/24 h), there was slightly higher clearance (95.5 [1.4%] vs. 91.2 [0.8%] mL/min/m, P=0.005) in those receiving TMP/SMX, with no difference in the 42 hour methotrexate concentration (0.59 [4.1%] vs. 0.66 [4.2%] μM, P=0.06). There was no difference in neutrophil counts based on TMP/SMX during HDMTX (P=0.83). TMP/SMX also did not have a significant impact on myelosuppression of low-dose methotrexate (40 mg/m) given during continuation therapy among 230 patients enrolled on a prior study (NCT00137111). Thus, we found no evidence for an interaction between methotrexate and TMP/SMX given prophylactically.

CD19-redirected chimeric antigen receptor-modified T cells: a promising immunotherapy for children and adults with B-cell acute lymphoblastic leukemia (ALL)

Relapsed and chemotherapy-refractory B-cell acute lymphoblastic leukemia (B-ALL) remain significant causes of cancer-associated morbidity and mortality for children and adults. Development of new molecularly targeted treatment strategies for patients with high-risk B-ALL is thus a major preclinical and clinical priority. Adoptive cellular therapy with patient-derived human T cells genetically engineered to express CD19 redirected chimeric antigen receptors (CD19 CAR T cells) is one immunotherapeutic modality that has recently demonstrated remarkable efficacy in re-inducing remission in patients with multiply relapsed B-ALL. Investigative teams at several major cancer centers are currently conducting phase I clinical trials in children and/or adults with relapsed/refractory B-ALL to assess the safety and to identify the maximally tolerated dose of each group's CD19 CAR T-cell product. All groups have reported major clinical toxicities associated with CD19 CAR T-cell treatment, including cytokine release syndrome (CRS) and macrophage activation syndrome, neurologic dysfunction and aplasia of normal B lymphocytes, while CD19 CAR T cells persist in vivo. Toxicities have generally been transient or manageable with supportive care measures. Some patients with life-threatening CD19 CAR T-cell induced sequelae have received anti-cytokine receptor antibody treatment to diminish CRS symptoms and/or corticosteroids to terminate CAR T-cell proliferation. Remarkably, 67-90% of children and adults with B-ALL treated with CD19 CAR T cells in these trials have achieved morphologic leukemia remission with many patients also in molecular remission. The duration of CD19 CAR T cell persistence in vivo has varied appreciably among treated patients and likely reflects differences in the CD19 CAR constructs utilized at each institution. CD19-positive and CD19-negative B-ALL relapses after CD19 CAR T-cell treatment have occurred in some patients. Phase II trials to assess the efficacy of CD19 CAR T-cell immunotherapy in larger cohorts of patients with relapsed/refractory B-ALL are ongoing or planned.

High expression of Midkine (MK) indicates poor prognosis in childhood acute lymphoblastic leukemia

OBJECTIVES

Midkine (MK) expression has been reported to be correlated with the poor prognosis of patients with various tumors. However, there are no data available about the prognostic value of MK expression in childhood acute lymphoblastic leukemia (ALL).

METHODS

In this study, MK mRNA expression was determined by real-time polymerase chain reaction in 120 childhood ALL and 30 healthy volunteers. Patients were dichotomized at the median value and divided into two groups: MK(low) group and MK(high) group.

RESULTS

MK(high) patients had higher white blood cell counts, higher peripheral blood blasts percentages, and higher minimal residual disease levels than MK(low) patients. Moreover, the MK gene was expressed significantly higher in patients with relapsed ALL than in patients who maintained complete remission or at diagnosis. MK(high) patients harbored inferior relapse-free survival (RFS, P = 0.047) and overall survival (OS, P = 0.022) than MK(low) patients, and high expression of MK was found to be independently predictive of inferior OS (P = 0.032) but not RFS (P = 0.077) in the overall cohort.

CONCLUSION AND DISCUSSION

MK high expression is an independent adverse prognostic factor in childhood ALL. Its level may be incorporated into an improved risk classification system for ALL and suggest the need of alternative regimens.

Antileukemic Efficacy of Continuous vs Discontinuous Dexamethasone in Murine Models of Acute Lymphoblastic Leukemia

Osteonecrosis is one of the most common, serious, toxicities resulting from the treatment of acute lymphoblastic leukemia. In recent years, pediatric acute lymphoblastic leukemia clinical trials have used discontinuous rather than continuous dosing of dexamethasone in an effort to reduce the incidence of osteonecrosis. However, it is not known whether discontinuous dosing would compromise antileukemic efficacy of glucocorticoids. Therefore, we tested the efficacy of discontinuous dexamethasone against continuous dexamethasone in murine models bearing human acute lymphoblastic leukemia xenografts (n = 8 patient samples) or murine BCR-ABL+ acute lymphoblastic leukemia. Plasma dexamethasone concentrations (7.9 to 212 nM) were similar to those achieved in children with acute lymphoblastic leukemia using conventional dosages. The median leukemia-free survival ranged from 16 to 59 days; dexamethasone prolonged survival from a median of 4 to 129 days in all seven dexamethasone-sensitive acute lymphoblastic leukemias. In the majority of cases (7 of 8 xenografts and the murine BCR-ABL model) we demonstrated equal efficacy of the two dexamethasone dosing regimens; whereas for one acute lymphoblastic leukemia sample, the discontinuous regimen yielded inferior antileukemic efficacy (log-rank p = 0.002). Our results support the clinical practice of using discontinuous rather than continuous dexamethasone dosing in patients with acute lymphoblastic leukemia.

Prognostic significance of being overweight and obese at diagnosis in children with acute lymphoblastic leukemia

This study tested the hypothesis that being overweight/obese at diagnosis of childhood ALL was related to risk of relapse. In a national cohort of 1033 patients from the UK, there was no evidence that weight status at diagnosis was related significantly to risk of relapse: log-rank test (P=0.90) with overweight and obesity as the exposure (n=917); individual (P=0.42) and stepwise (P=0.96) proportional hazards models, with BMI Z score as the exposure. The study does not support the hypothesis that being overweight/obese at diagnosis impairs prognosis in childhood ALL in the UK.

Clinical characteristics and treatment outcome of childhood acute lymphoblastic leukemia in Saudi Arabia: a multi-institutional retrospective national collaborative study

BACKGROUND

Treatment of childhood acute lymphoblastic leukemia (ALL) has been available in Saudi Arabia (SA) for over 30 years; however, only limited data have been published from there. This study was conducted to establish processes for collaborative data collection and provide clinical characteristics and outcome of children with ALL in SA.

PROCEDURE

Clinical data for patients diagnosed from 2004 to 2008 were retrospectively collected at eight institutions and entered remotely into a custom-built database. Statistics regarding clinical and genetic characteristics and treatment outcome were calculated.

RESULTS

The 594 evaluable patients had a median age of 4.37 years and 56.4% were boys. Majority of patients had B-precursor ALL while 10.7% had T-ALL. CNS leukemia was present in 5.2% of patients. The distribution of common genetic abnormalities was similar to that reported from western populations, with 24.6% hyperdiploidy, 21% RUNX1-ETV6 positivity, 4.2% BCR-ABL1 positivity, and 2.5% with MLL gene rearrangement. Patients received risk-adapted therapy according to various protocols, although treatment strategies for the majority were similar. Five-year OS, RFS and EFS were 86.9%, 79.1%, and 73.3%, respectively. The OS for patients with pre-B ALL was significantly higher than for T-ALL (88.0% vs. 71.8%; P = 0.019, Log-Rank test). Patients with pre-B ALL categorized as low-risk by NCI/Rome criteria and those with hyperdiploidy had OS of 93.4% and 95.8%, respectively.

CONCLUSIONS

The characteristics of childhood ALL in SA are similar to those observed in developed countries. Future prospective studies utilizing unified national protocols are needed to further improve the outcome of our patients.

IKZF1 and CRLF2 gene alterations correlate with poor prognosis in Japanese BCR-ABL1-negative high-risk B-cell precursor acute lymphoblastic leukemia

BACKGROUND

Genome-wide analysis studies have demonstrated that IKZF1, CRLF2, and JAK2 gene alterations correlate with poor prognosis in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL). However, the prognostic significance for these gene alterations has not been clarified in Japanese patients.

PROCEDURE

A total of 194 patients with BCP-ALL enrolled in the Japanese Children's Cancer & Leukemia Study Group ALL 2004 clinical trial were assessed for the presence of three different gene alterations: IKZF1 deletions, CRLF2 expression and JAK2 mutation.

RESULTS

IKZF1 deletions and CRLF2-high expression were identified in 22 of 177 (12%) patients and in 15 of 141 (11%) patients, respectively. However, JAK2 R683 mutation was detected only one of 177 patients. The 4-year event-free survival (4y-EFS) was different when comparing patients with or without IKZF1 deletions (68.2% vs. 85.2%; P = 0.04) and was also different when comparing patients with different CRLF2 expression levels (high, 66.7% vs. low, 88.1%; P = 0.03). The differences in 4y-EFS were statistically significant in patients with ALL in the National Cancer Institute (NCI)-high risk group (HR-ALL) (IKZF1 deletions: yes, 58.3% vs. no, 87.0%, P = 0.02; CRLF2 expression: high, 55.6% vs. low, 85.3%, P = 0.04) but not in patients with ALL in the NCI-standard risk group (SR-ALL; IKZF1 deletions: yes, 80.0% vs. no, 84.4%, P = 0.75; CRLF2 expression: high, 83.3% vs. low, 89.2%, P = 0.77). Coexistence of IKZF1 deletions and CRLF2-high expression associated with poor outcomes.

CONCLUSIONS

IKZF1 deletions and CRLF2-high expression predicted poor outcomes in patients with HR-ALL but not in patients with SR-ALL in our Japanese cohort.

Abnormal developmental control of replication-timing domains in pediatric acute lymphoblastic leukemia

Abnormal replication timing has been observed in cancer but no study has comprehensively evaluated this misregulation. We generated genome-wide replication-timing profiles for pediatric leukemias from 17 patients and three cell lines, as well as normal B and T cells. Nonleukemic EBV-transformed lymphoblastoid cell lines displayed highly stable replication-timing profiles that were more similar to normal T cells than to leukemias. Leukemias were more similar to each other than to B and T cells but were considerably more heterogeneous than nonleukemic controls. Some differences were patient specific, while others were found in all leukemic samples, potentially representing early epigenetic events. Differences encompassed large segments of chromosomes and included genes implicated in other types of cancer. Remarkably, differences that distinguished leukemias aligned in register to the boundaries of developmentally regulated replication-timing domains that distinguish normal cell types. Most changes did not coincide with copy-number variation or translocations. However, many of the changes that were associated with translocations in some leukemias were also shared between all leukemic samples independent of the genetic lesion, suggesting that they precede and possibly predispose chromosomes to the translocation. Altogether, our results identify sites of abnormal developmental control of DNA replication in cancer that reveal the significance of replication-timing boundaries to chromosome structure and function and support the replication domain model of replication-timing regulation. They also open new avenues of investigation into the chromosomal basis of cancer and provide a potential novel source of epigenetic cancer biomarkers.

Absence of biallelic TCRγ deletion predicts induction failure and poorer outcomes in childhood T-cell acute lymphoblastic leukemia

BACKGROUND

The absence of biallelic TCRγ deletion (ABD) is a characteristic of early thymocyte precursors before V(D)J recombination. The ABD was reported to predict early treatment failure in T-cell acute lymphoblastic leukemia (ALL). This study aimed to investigate its prognostic value in Taiwanese patients with T-cell ALL.

PROCEDURE

Forty-five children with T-cell ALL were enrolled from six medical centers in Taiwan. Quantitative DNA polymerase chain reaction (Q-PCR) was performed to check the status of TCRγ deletion. The threshold for homozygous deletions by Q-PCR was defined as a fold-change <0.35.

RESULTS

ABD was found in 20 patients [20:45] who had higher incidences of induction failure than those without ABD (P = 0.03; hazard ratio [HR] = 8.13; 95% confidence interval [95% CI] = 1.23-53.77) after multivariate regression analysis. Patents with ABD also had inferior EFS and OS (P = 0.071 and 0.0196, respectively). Multivariate Cox analysis indicated that the association between ABD and overall survival was independent of age and leukocyte count on presentation (P = 0.036; HR = 4.25; 95% CI = 1.10-16.42).

CONCLUSIONS

The absence of TCRγ deletion is a predictor of a poor response to induction chemotherapy for pediatric patients with T-cell ALL in Taiwan. Providing patients with T-cell ALL and ABD with alternative regimens may be worthwhile to test in future clinical trials.

Gene expression signatures and ex vivo drug sensitivity profiles in children with acute lymphoblastic leukemia

INTRODUCTION

Causes of treatment failure in acute lymphoblastic leukemia (ALL) are still poorly understood. Microarray technology gives new possibilities for the analysis of the biology of leukemias. We hypothesize that drug sensitivity in pediatric ALL is driven by specific molecular mechanisms that correlate with gene expression profiles assessed by microarray analysis.

OBJECTIVE

The aim of the study was to determine the ex vivo resistance profiles of 20 antileukemic drugs and gene expression profiles, with relation to response to initial therapy.

PATIENTS AND METHODS

Lymphoblasts were analyzed after bone marrow biopsy was obtained from 56 patients. The profile of in vitro resistance to drugs was determined in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazoliumbromide (MTT) cytotoxicity assay. High-quality total RNA was prepared and hybridized to oligonucleotide arrays HG-U133A 2.0 Chip (Affymetrix). The expression of selected genes was tested by qualitative reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS AND CONCLUSIONS

The exposure of leukemic blasts to drugs initiates a complex cellular response, which reflects global changes in gene expression. Changes in the expression of several genes are highly correlated with drug resistance.

Multidisciplinary care in pediatric oncology

This paper describes the significant advances in the treatment of childhood cancer and supportive care that have occurred over the last several decades and details how these advances have led to improved survival and quality of life (QOL) for children with cancer through a multidisciplinary approach to care. Advances in the basic sciences, general medicine, cooperative research protocols, and policy guidelines have influenced and guided the multidisciplinary approach in pediatric oncology care across the spectrum from diagnosis through long-term survival. Two case studies are provided to highlight the nature and scope of multidisciplinary care in pediatric oncology care.

Comparison of the approaches to non-febrile neutropenia developing in children with acute lymphoblastic leukemia

The objectives of this study was to investigate of the influences of high-dose (20 mg/kg/day) methyl prednisolone (HDMP) and granulocyte colony stimulating factor (G-CSF) in shortening the duration of chemotherapy-induced neutropenia encountered in children with ALL receiving maintenance therapy. Sixty-four non-febrile neutropenic attacks developed in 29 patients with ALL receiving St Jude XIII maintenance protocol were evaluated retrospectively. The patients were clinically followed up without drugs for shortening the duration of neutropenia in 21 (32.8%) attacs, while HDMP and G-CSF were administered in 26 (40.6%) and 17 (26.6%) attacks, respectively. After the detection of neutropenia, restoration of neutrophil counts at 2nd or 4th days to the levels that allow resuming the chemotherapy were considered as success. While second day and overall success rates in patients administered HDMP and G-CSF were significantly higher than the patients who were observed clinically. Both second day and overall neutrophil counts were significantly higher in patients administered G-CSF than the other groups. Methyl prednisolone and G-CSF treatments were well-tolerated by the patients. The cost-per neutropenic attack was significantly higher in G-CSF group than of the HDMP group. Especially in patients experiencing frequent neutropenic attacks and hence interruptions of the therapy, one of the myelopoiesis induction therapies can be used to shorten the duration of neutropenia. For this indication short-course HDMP therapy can be considered as an alternative to G-CSF in this patients due to its relatively low cost, amenability to outpatient administration, and well-tolerability by children.

Cytotoxicity, drug combinability, and biological correlates of ABT-737 against acute lymphoblastic leukemia cells with MLL rearrangement

BACKGROUND

ABT-737 is a BH3 mimetic small-molecule inhibitor that binds with high affinity to Bcl-2 to induce apoptosis in malignant cells and has shown promise as an effective anti-leukemic agent in pediatric preclinical tests. This study focuses on the effects of ABT-737 on leukemia cells with MLL rearrangement and identifies some of the biological correlates of its activity.

PROCEDURE

Cells were cultured in the presence of increasing concentrations of ABT-737 alone or in combination with other agents. After 4 days in culture, cell growth inhibition was measured by Alamar blue assay. The expression and activation of potential intracellular targets of ABT-737 activity were determined by Western blot analysis.

RESULTS

Significant Bcl-2 expression was detected in all infant leukemia cells investigated. ABT-737 induced cell death in all cell lines studied although the IC(50) values differed somewhat between cell lines. Western blot analysis identified the effects of ABT-737 on survival and apoptosis-regulatory proteins PARP, caspase-8, and cytochrome-c. Drug combination studies indicated synergy with distinct anti-neoplastic agents, including the multi-tyrosine kinase inhibitor sunitinib. This effective drug synergy appears to be mediated by the combined inhibition of Bcl-2 and intracellular signaling pathways.

CONCLUSIONS

We describe the in vitro studies to demonstrate the activity and drug combinability of ABT-737 against MLL rearranged leukemia cells. In addition, identification of the molecular changes that occur in the presence of ABT-737 provides information regarding effective target validation and target modulation analyses in future clinical trials.

Late recurrence of childhood T-cell acute lymphoblastic leukemia frequently represents a second leukemia rather than a relapse: first evidence for genetic predisposition

PURPOSE

Relapse of childhood T-cell acute lymphoblastic leukemia (T-ALL) often occurs during treatment, but in some cases, leukemia re-emerges off therapy. On the basis of previous analyses of T-cell receptor (TCR) gene rearrangement patterns, we hypothesized that some late recurrences of T-ALL might in fact represent second leukemias.

PATIENTS AND METHODS

In 22 patients with T-ALL who had late relapses (at least 2.5 years from diagnosis), we studied TCR gene rearrangement status at first and second presentation, NOTCH1 gene mutations, and the presence of the SIL-TAL1 gene fusion. We performed genome-wide copy number and homozygosity analysis by using oligonucleotide- and single nucleotide polymorphism (SNP) -based arrays.

RESULTS

We found evidence of a common clonal origin between diagnosis and relapse in 14 patients (64%). This was based on concordant TCR gene rearrangements (12 patients) or concordant genetic aberrations, as revealed by genome-wide copy number analysis (two patients). In the remaining eight patients (36%), TCR gene rearrangement sequences had completely changed between diagnosis and relapse, and gene copy number analysis showed markedly different patterns of genomic aberrations, suggesting a second T-ALL rather than a resurgence of the original clone. Moreover, NOTCH1 mutation patterns were different at diagnosis and relapse in five of these eight patients. In one patient with a second T-ALL, SNP analysis revealed a germline del(11)(p12;p13), a known recurrent aberration in T-ALL.

CONCLUSION

More than one third of late T-ALL recurrences are, in fact, second leukemias. Germline genetic abnormalities might contribute to the susceptibility of some patients to develop T-ALL.