Imatinib after induction for treatment of children and adolescents with Philadelphia-chromosome-positive acute lymphoblastic leukaemia (EsPhALL): a randomised, open-label, intergroup study

Background

Trials of imatinib have provided evidence of activity in adults with Philadelphia-chromosome-positive acute lymphoblastic leukaemia (ALL), but the drug's role when given with multidrug chemotherapy to children is unknown. This study assesses the safety and efficacy of oral imatinib in association with a Berlin–Frankfurt–Munster intensive chemotherapy regimen and allogeneic stem-cell transplantation for paediatric patients with Philadelphia-chromosome-positive ALL.

Methods

Patients aged 1–18 years recruited to national trials of front-line treatment for ALL were eligible if they had t(9;22)(q34;q11). Patients with abnormal renal or hepatic function, or an active systemic infection, were ineligible. Patients were enrolled by ten study groups between 2004 and 2009, and were classified as good risk or poor risk according to early response to induction treatment. Good-risk patients were randomly assigned by a web-based system with permuted blocks (size four) to receive post-induction imatinib with chemotherapy or chemotherapy only in a 1:1 ratio, while all poor-risk patients received post-induction imatinib with chemotherapy. Patients were stratified by study group. The chemotherapy regimen was modelled on a Berlin–Frankfurt–Munster high-risk backbone; all received four post-induction blocks of chemotherapy after which they became eligible for stem-cell transplantation. The primary endpoints were disease-free survival at 4 years in the good-risk group and event-free survival at 4 years in the poor-risk group, analysed by intention to treat and a secondary analysis of patients as treated. The trial is registered with EudraCT (2004-001647-30) and ClinicalTrials.gov, number NCT00287105.

Findings

Between Jan 1, 2004, and Dec 31, 2009, we screened 229 patients and enrolled 178: 108 were good risk and 70 poor risk. 46 good-risk patients were assigned to receive imatinib and 44 to receive no imatinib. Median follow-up was 3·1 years (IQR 2·0–4·6). 4-year disease-free survival was 72·9% (95% CI 56·1–84·1) in the good-risk, imatinib group versus 61·7% (45·0–74·7) in the good-risk, no imatinib group (p=0·24). The hazard ratio (HR) for failure, adjusted for minimal residual disease, was 0·63 (0·28–1·41; p=0·26). The as-treated analysis showed 4-year disease-free survival was 75·2% (61·0–84·9) for good-risk patients receiving imatinib and 55·9% (36·1–71·7) for those who did not receive imatinib (p=0·06). 4-year event-free survival for poor-risk patients was 53·5% (40·4–65·0). Serious adverse events were much the same in the good-risk groups, with infections caused by myelosuppression the most common. 16 patients in the good-risk imatinib group versus ten in the good-risk, no imatinib group (p=0·64), and 24 in the poor-risk group, had a serious adverse event.

Interpretation

Our results suggests that imatinib in conjunction with intensive chemotherapy is well tolerated and might be beneficial for treatment of children with Philadelphia-chromosome-positive ALL.

Funding

Projet Hospitalier de Recherche Clinique-Cancer (France), Fondazione Tettamanti-De Marchi and Associazione Italiana per la Ricerca sul Cancro (Italy), Novartis Germany, Cancer Research UK, Leukaemia Lymphoma Research, and Central Manchester University Hospitals Foundation Trust.

Diagnosis and management of neonatal leukaemia

Leukaemia in neonates (infants <1 month) is rare, whereby neonatal acute myeloid leukaemia (AML) is more frequent than neonatal acute lymphoblastic leukaemia (ALL). High mortality rates are observed, though AML has a better prognosis than ALL. Neonatal leukaemia is typically presented with hepatosplenomegaly, leukaemia cutis and/or hyperleucocytosis. Congenital infections should be ruled out before diagnosis. Rearrangement of the MLL gene is the most frequently occurring genetic aberration. Treatment includes intensive multi-agent chemotherapy, usually with age-related dose adjustments next to supportive care. Treatment intensification for ALL could be indicated in the future as the dismal prognosis is subject to high relapse rates in ALL.

Frequency of WT1 and 11p15 constitutional aberrations and phenotypic correlation in childhood Wilms tumour patients

INTRODUCTION

In 9-17% of Wilms tumour patients a predisposing syndrome is present, in particular WT1-associated syndromes and overgrowth syndromes. Constitutional WT1 mutations or epigenetic changes on chromosome 11p15 have also been described in Wilms tumour patients without phenotypic abnormalities. Thus, the absence of phenotypic abnormalities does not exclude the presence of a genetic predisposition, suggesting that more Wilms tumour patients may have a constitutional abnormality. Therefore, we investigated the frequency of constitutional aberrations in combination with phenotype.

PATIENTS & METHODS

Clinical genetic assessment, as well as molecular analysis of WT1 and locus 11p15 was offered to a single-centre cohort of 109 childhood Wilms tumour patients.

RESULTS

Twelve patients (11%) had a WT1 aberration and eight patients (8%) had an 11p15 aberration. Of the 12 patients with a WT1 aberration, four had WAGR syndrome (Wilms tumor, aniridia, genitourinary malformations and mental retardation), one had Denys-Drash syndrome, four had genitourinary anomalies without other syndromic features and three had bilateral disease with stromal-predominant histology at young age without congenital anomalies. Of the eight patients with an 11p15 aberration, four had Beckwith-Wiedemann syndrome (BWS), two had minor features of BWS and two had no stigmata of BWS or hemihypertrophy.

CONCLUSION

Constitutional WT1 or 11p15 aberrations are frequent in Wilms tumour patients and careful clinical assessment can identify the majority of these patients. Therefore, we would recommend offering clinical genetic counselling to all Wilms tumour patients, as well as molecular analysis to patients with clinical signs of a syndrome or with features that may indicate a constitutional WT1 or 11p15 aberration.

Impact of treatment reduction for childhood acute lymphoblastic leukemia on serum immunoglobulins and antibodies against vaccine-preventable diseases

BACKGROUND

The consequences of current intensive chemotherapy for childhood acute lymphoblastic leukemia (ALL) for immune defense are a matter of concern. The purpose of this study was to examine the effect of reduced compared with intensive (conventional) ALL chemotherapy on serum immunoglobulin levels and specific antibody concentrations against vaccine-preventable diseases.

PROCEDURE

Patients treated according to Dutch Childhood Oncology Group ALL 10 protocol were stratified by minimal residual disease to receive reduced (standard risk; SR) or intensive (medium risk; MR) intensification/maintenance treatment. Between November 2004 and July 2009 we compared serum immunoglobulins of 110 patients and specific antibodies against diphtheria toxin, tetanus toxin, and Bordetella pertussis antigens of 41 patients of SR and MR groups during chemotherapy.

RESULTS

Immunoglobulin levels showed significantly different patterns between the SR and MR groups. In the MR group IgG, IgA, and IgM levels decreased towards the end of intensive treatment; in the SR group IgG levels increased while IgA and IgM stabilized. In both groups IgM and IgG levels were most affected. Specific antibody levels against vaccine-preventable diseases decreased in both groups, but more profound in MR group.

CONCLUSIONS

Although reduced chemotherapy is beneficial for immunoglobulin level recovery and might prevent susceptibility for infections, specific antibodies remain decreased.

Differentially expressed miRNAs in cytogenetic and molecular subtypes of pediatric acute myeloid leukemia

BACKGROUND

miRNAs regulate gene expression, and thus play an important role in critical cellular processes. Aberrant miRNA expression patterns have been found in various types of cancer. So far, information about the expression of miRNAs in pediatric acute myeloid leukemia is limited.

PROCEDURE

We studied expression of miR-29a, -155, -196a, and -196b by stem-loop based RT-qPCR in 82 pediatric acute myeloid leukemia patients selected to represent relevant cytogenetic and molecular subgroups.

RESULTS

High miR-196a and -b expression was observed in patients carrying MLL gene rearrangements (P < 0.001), NPM1 mutations (P < 0.001), or FLT3-ITD in a cytogenetically normal background (P ≤ 0.02), compared to all other patients. In contrast, CEBPA mutated cases had a low expression of miR-196a and -b (P ≤ 0.001). Expression of miR-196a and -b was correlated with expression of neighboring HOXA and HOXB genes (Spearman's r = 0.46-0.82, P < 0.01). Expression of miR-155 was not related to cytogenetic features but high expression of miR-155 was observed in FLT3-ITD (P = 0.001) and NPM1-mutated cases (P = 0.04). Lower miR-29a expression was mainly observed in MLL-rearranged pediatric acute myeloid leukemia, specifically in cases carrying t(10;11) (P < 0.001).

CONCLUSIONS

We show aberrant expression of specific miRNAs in clinically relevant cytogenetic and molecular subgroups of pediatric acute myeloid leukemia, suggesting a role for these miRNAs in the underlying biology in these specific subgroups.

Adrenal function in adult long-term survivors of nephroblastoma and neuroblastoma

BACKGROUND

Adrenal insufficiency, or relative insufficiency, might partly explain increased mortality rates in nephroblastoma and neuroblastoma survivors after unilateral adrenalectomy.

OBJECTIVE

To assess adrenal function and its metabolic effects in survivors after adrenalectomy.

METHODS

In this cross-sectional study, 67 adult long-term survivors of nephroblastoma, 36 survivors of neuroblastoma and 49 control subjects participated. Adrenal function was assessed by a 1μg short Synacthen-test. Levels of cortisol, adrenocorticotrophic hormone (ACTH), low (LDL-C) and high-density lipoprotein-cholesterol (HDL-C), triglycerides, apolipoprotein-B, glucose and insulin were assessed in blood samples taken at baseline. In addition, cortisol levels were assessed after 30 (t=30) and 60 min. Homoeostatic Model Assessment (HOMA) was calculated.

RESULTS

Adrenal insufficiency was not present in survivors. Interestingly, baseline serum cortisol levels were higher in survivors after unilateral adrenalectomy (mean 503 nmol/l) (N=46) than in survivors with both adrenals intact (mean 393 nmol/l, P=0.002) (N=52), and than in controls (mean 399 nmol/l, P=0.013) (N=49). After correcting for age, sex and use of oral oestrogens, unilateral adrenalectomy was independently associated with elevated baseline cortisol and ACTH levels. Baseline cortisol levels were positively associated with triglycerides (P<0.001), LDL-C (P=0.004), apolipoprotein-B (P<0.001) and HOMA (P=0.008).

CONCLUSIONS

No adrenal insufficiency was observed in survivors of nephroblastoma and neuroblastoma. Survivors treated with unilateral adrenalectomy had relatively high basal cortisol and ACTH levels, indicating a higher central setpoint of the hypothalamic-pituitary-adrenal axis. This higher setpoint was associated with lipid concentrations and insulin resistance and can therefore influence the cardiovascular risk profile in long-term survivors of nephroblastoma and neuroblastoma.

Abstract 2490: High AXL promotes migration in non-MYCN amplified neuroblastoma cell lines

Background: Neuroblastomas (NBL) are tumors with a high rate of metastases (50% of patients). In general, in NBL MYCN amplification (NMA) is the most important prognostic factor. However NMA is infrequent and 70% of NBL are non-NMA tumors and not much is known about the driving oncogenic event. Recently, we identified among 17 NBL cell lines a group of non-NMA NBL cell lines with a distinct gene expression profile (HU133plus2.0 arrays, Affymetrix) and high expression of the AXL gene. AXL is a tyrosine kinase receptor, associated with the metastatic process of several cancers. We hypothesized that AXL contributes to metastsizing potential in non-NMA neuroblastomas and tested if AXL silencing diminishes malignant properties of high AXL expressing cell lines. Results: High expression of AXL was detected in G-IM-EN, SK-N-AS and two subclonal cell lines SH-EP-2 and SH-EP-21N. AXL was silenced (lentiviral AXL shRNA expression plasmids, pLKO.1_shAXL, Sigma-Aldrich) in GI-M-EN and SH-EP-2 with an infection efficiency of &gt;90% and 80-85% AXL-mRNA knockdown. We examined the silencing effect on migration and invasion. A significant reduction of migration (74.7%) and invasion (99.8%) was achieved in GI-M-EN. In the intermediate AXL expressing expressing cell line SH-EP-2 migration reduction was less (41.9%). Furthermore, GI-M-EN and SH-EP-2 were compared for cytoskeletal, morphological changes after silencing. Cells became rounded with small lamellipodia and filopodia and F-actin fluorescent staining showed induction of F-actin positive stress-fibers (17.3%), both most prominent in high AXL expressing GI-M-EN. In SH-EP-2 the number of cells with stress fibers was increased (9.9%). Expression of, matrix metalloproteinase 9 frequent down-stream target of EMT-like processes, was not changed upon silencing of AXL. Also, we observed no effects on cell proliferation, apoptosis or downstream pathways (PI3K-AKT, MAPK-ERK pathway). Conclusion: The AXL gene is highly expressed in a subset of non-NMA NBL cell lines and seems involved in migratory and invasion properties. AXL is a possible mediator of NBL metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2490. doi:1538-7445.AM2012-2490

Abstract 768: MCL1 and glycolysis synergistically induce prednisolone resistance, which can be therapeutically reversed

Although cure rates for acute lymphoblastic leukemia (ALL) have greatly improved, contemporary treatment is still ineffective in 20% of patients. Unsuccessful treatment can be mainly ascribed to resistance towards antileukemic drugs. In particular prednisolone is highly associated with poor prognosis. Overcoming drug resistance is therefore necessary to increase current survival rates. Microarray analysis of precursor B-ALL patients revealed MCL1 as an important gene involved in prednisolone resistance (Holleman, N Engl J Med 2004). We demonstrated sensitization towards prednisolone after lentiviral silencing of MCL1 in prednisolone resistant leukemic cell lines (Stam, Blood 2009). These results point to MCL1 as an interesting candidate for targeted therapy. We also discovered that cells upregulate their glucose consumption level to protect from prednisolone induced apoptosis. 2-Deoxyglucose (2DG), an inhibitor of glycolysis, sensitized for prednisolone in leukemic cell lines and patients’ cells (Hulleman, Blood 2009). We here provide evidence for an inter-connection between MCL1, glycolysis and prednisolone resistance. A clear increase in glucose consumption was observed after targeting MCL1 in leukemic cells by both lentiviral silencing and mRNA antagonists. This suggests that cells upregulate glycolysis to prevent apoptosis induced upon MCL1 knockdown. Indeed, co-exposure to 2DG substantially decreased the proliferation rate of MCL1-silenced cells, and most importantly, synergized with silencing of MCL1 in reversing resistance to prednisolone. Altogether these data provide evidence for concomitant causes of resistance and indicate that MCL1 silencing and glycolysis inhibition can serve as potent ways to reverse resistance to prednisolone in acute leukemia.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 768. doi:1538-7445.AM2012-768

The significance of PTEN and AKT aberrations in pediatric T-cell acute lymphoblastic leukemia

BACKGROUND

PI3K/AKT pathway mutations are found in T-cell acute lymphoblastic leukemia, but their overall impact and associations with other genetic aberrations is unknown. PTEN mutations have been proposed as secondary mutations that follow NOTCH1-activating mutations and cause cellular resistance to γ-secretase inhibitors.

DESIGN AND METHODS

The impact of PTEN, PI3K and AKT aberrations was studied in a genetically well-characterized pediatric T-cell leukemia patient cohort (n=146) treated on DCOG or COALL protocols.

RESULTS

PTEN and AKT E17K aberrations were detected in 13% and 2% of patients, respectively. Defective PTEN-splicing was identified in incidental cases. Patients without PTEN protein but lacking exon-, splice-, promoter mutations or promoter hypermethylation were present. PTEN/AKT mutations were especially abundant in TAL- or LMO-rearranged leukemia but nearly absent in TLX3-rearranged patients (P=0.03), the opposite to that observed for NOTCH1-activating mutations. Most PTEN/AKT mutant patients either lacked NOTCH1-activating mutations (P=0.006) or had weak NOTCH1-activating mutations (P=0.011), and consequently expressed low intracellular NOTCH1, cMYC and MUSASHI levels. T-cell leukemia patients without PTEN/AKT and NOTCH1-activating mutations fared well, with a cumulative incidence of relapse of only 8% versus 35% for PTEN/AKT and/or NOTCH1-activated patients (P=0.005).

CONCLUSIONS

PI3K/AKT pathway aberrations are present in 18% of pediatric T-cell acute lymphoblastic leukemia patients. Absence of strong NOTCH1-activating mutations in these cases may explain cellular insensitivity to γ-secretase inhibitors.

Outcome in children with Down's syndrome and acute lymphoblastic leukemia: role of IKZF1 deletions and CRLF2 aberrations

Children with Down's syndrome (DS) have an increased risk of developing acute lymphoblastic leukemia (ALL) and have a low frequency of established genetic aberrations. We aimed to determine which genetic abnormalities are involved in DS ALL. We studied the frequency and prognostic value of deletions in B-cell development genes and aberrations of janus kinase 2 (JAK2) and cytokine receptor-like factor 2 (CRLF2) using array-comparative genomic hybridization, and multiplex ligation-dependent probe amplification in a population-based cohort of 34 Dutch Childhood Oncology Group DS ALL samples. A population-based cohort of 88 DS samples from the UK trials was used to validate survival estimates for IKZF1 and CRLF2 abnormalities. In total, 50% of DS ALL patients had ≥1 deletion in the B-cell development genes: PAX5 (12%), VPREB1 (18%) and IKZF1 (35%). JAK2 was mutated in 15% of patients, genomic CRLF2 rearrangements in 62%. Outcome was significantly worse in patients with IKZF1 deletions (6-year event-free survival (EFS) 45 ± 16% vs 95 ± 4%; P=0.002), which was confirmed in the validation cohort (6-year EFS 21 ± 12% vs 58 ± 11%; P=0.002). This IKZF1 deletion was a strong independent predictor for outcome (hazard ratio EFS 3.05; P=0.001). Neither CRLF2 nor JAK2 were predictors for worse prognosis. If confirmed in prospective series, IKZF1 deletions may be used for risk-group stratification in DS ALL.

Population pharmacokinetics of native Escherichia coli asparaginase

The main aim of this analysis was to characterize the population pharmacokinetics of native Escherichia coli asparaginase (ASNase medac) in pediatric patients with previously untreated acute lymphoblastic leukemia. Secondary objective was to give further evidence for bioequivalence between ASNase medac and a new recombinant ASNase preparation. The authors reanalyzed 233 plasma samples from 16 children treated according to the DCOG-ALL 10 protocol (5000 U/m(2) ASNase medac) using NONMEM. Subsequently, assessment of bioequivalence was performed by including the preparation as a categorical covariate into the PopPK model when analyzing data of both preparations (480 samples, 32 children). A linear 2-compartment model with first-order elimination sufficiently described ASNase medac pharmacokinetics. The parameters found were as follows: total body clearance 0.13 L/h ± 12.4% per 1.73 m(2), volume of distribution in the central compartment 4.11 L ± 12.3% per 70 kg, volume of distribution in the peripheral compartment 1.63 L per 70 kg and intercompartmental clearance 0.106 L/h (mean ± interindividual variability). A visual predictive check procedure and simulation of different dosages ASNase medac administered in the ALL-BFM protocol indicated adequate model performance. Assessment of bioequivalence provided a difference of about 14% in clearance of both preparations being too small to be considered as clinically relevant. A population pharmacokinetic model of ASNase medac in pediatric patients with previously untreated acute lymphoblastic leukemia was established. The model was able to describe asparaginase activity of different dosages in the ALL-BFM protocol and provides further evidence for bioequivalence between ASNase medac and a new recombinant asparaginase preparation.

Elevated S100A8/S100A9 expression causes glucocorticoid resistance in MLL-rearranged infant acute lymphoblastic leukemia

MLL-rearranged acute lymphoblastic leukemia (ALL) in infants is characterized by a poor clinical outcome and resistance to glucocorticoids (for example, prednisone and dexamethasone). As both the response to prednisolone in vitro and prednisone in vivo are predictive for clinical outcome, understanding and overcoming glucocorticoid resistance remains an essential step towards improving prognosis. Prednisolone-induced apoptosis depends on glucocorticoid-evoked Ca(2+) fluxes from the endoplasmic reticulum towards the mitochondria. Here, we demonstrate that in MLL-rearranged infant ALL, over-expression of S100A8 and S100A9 is associated with failure to induce free-cytosolic Ca(2+) and prednisolone resistance. Furthermore, we demonstrate that enforced expression of S100A8/S100A9 in prednisolone-sensitive MLL-rearranged ALL cells, rapidly leads to prednisolone resistance as a result of S100A8/S100A9 mediated suppression of prednisolone-induced free-cytosolic Ca(2+) levels. In addition, the Src kinase inhibitor PP2 markedly sensitized MLL-rearranged ALL cells otherwise resistant to prednisolone, via downregulation of S100A8 and S100A9, which allowed prednisolone-induced Ca(2+) fluxes to reach the mitochondria and trigger apoptosis. On the basis of this novel mechanism of prednisolone resistance, we propose that developing more specific S100A8/S100A9 inhibitors may well be beneficial for prednisolone-resistant MLL-rearranged infant ALL patients.

Different outcome in older children with acute lymphoblastic leukemia with different treatment protocols in the Netherlands

BACKGROUND

From 1991 until 2004 children with acute lymphoblastic leukemia (ALL) in the Netherlands were treated according to protocols ALL-8 and ALL-9 which were based on different principles. An earlier study showed that the outcome of adolescents highly differed on these protocols.

PROCEDURE

In this retrospective study, we analyzed whether the outcome of older children 10-15 years of age at diagnosis differed between the Berlin-Frankfurt-Münster (BFM)-based ALL-8 regimen and the ALL-9 regimen. Two hundred fifty-four older children who were treated according to protocol ALL-8 (n = 82) or ALL-9 (n = 172) were included in the analysis.

RESULTS

A higher 5-year event-free survival (EFS) rate was found for patients treated according to ALL-8 compared to ALL-9 (79 ± 5% vs. 65 ± 4%, P = 0.02). Patient characteristics did not differ except for a slightly higher age in ALL-8. Therefore, additional analyses were done including only patients who were 12-15 years of age. In this age group there was also a difference in the 5-year EFS (82 ± 5% vs. 61 ± 5%, P = 0.00) as well as in the 5-year overall survival rate; 89 ± 4% compared to 68 ± 5%, respectively (P = 0.01). Major difference between protocols was the use of a consolidation and reinduction/intensification course and higher cumulative doses of asparaginase, methotrexate, and anthracyclines in ALL-8.

CONCLUSIONS

Children 10-15 years of age have been undertreated with the ALL-9 regimen and benefit by intensive treatment components as used in ALL-8. We recommend using BFM-based protocols for these older children with ALL.

Characterization of a pediatric T-cell acute lymphoblastic leukemia patient with simultaneous LYL1 and LMO2 rearrangements

Translocation of the LYL1 oncogene are rare in T-cell acute lymphoblastic leukemia, whereas the homologous TAL1 gene is rearranged in approximately 20% of patients. Previous gene-expression studies have identified an immature T-cell acute lymphoblastic leukemia subgroup with high LYL1 expression in the absence of chromosomal aberrations. Molecular characterization of a t(7;19)(q34;p13) in a pediatric T-cell acute lymphoblastic leukemia patient led to the identification of a translocation between the TRB@ and LYL1 loci. Similar to incidental T-cell acute lymphoblastic leukemia cases with synergistic, double translocations affecting TAL1/2 and LMO1/2 oncogenes, this LYL1-translocated patient also had an LMO2 rearrangement pointing to oncogenic cooperation between LYL1 and LMO2. In hierarchical cluster analyses based on gene-expression data, this sample consistently clustered along with cases having TAL1 or LMO2 rearrangements. Therefore, LYL1-rearranged cases are not necessarily associated with immature T-cell development, despite high LYL1 levels, but elicit a TALLMO expression signature.

Prospective Study on Incidence, Risk Factors, and Long-Term Outcome of Osteonecrosis in Pediatric Acute Lymphoblastic Leukemia

Purpose

We studied cumulative incidence, risk factors, therapeutic strategies, and outcome of symptomatic osteonecrosis in pediatric patients with acute lymphoblastic leukemia (ALL).

Patients and Methods

Cumulative incidence of osteonecrosis was assessed prospectively in 694 patients treated with the dexamethasone-based Dutch Child Oncology Group–ALL9 protocol. Osteonecrosis was defined by development of symptoms (National Cancer Institute grade 2 to 4) during treatment or within 1 year after treatment discontinuation, confirmed by magnetic resonance imaging. We evaluated risk factors for osteonecrosis using logistic multivariate regression. To describe outcome, we reviewed clinical and radiologic information after antileukemic treatment 1 year or more after osteonecrosis diagnosis.

Results

Cumulative incidence of osteonecrosis at 3 years was 6.1%. After adjustment for treatment center, logistic multivariate regression identified age (odds ratio [OR], 1.47; P < .01) and female sex (OR, 2.23; P = .04) as independent risk factors. Median age at diagnosis of ALL in patients with osteonecrosis was 13.5 years, compared with 4.7 years in those without. In 21 (55%) of 38 patients with osteonecrosis, chemotherapy was adjusted. Seven patients (18%) underwent surgery: five joint-preserving procedures and two total-hip arthroplasties. Clinical follow-up of 35 patients was evaluated; median follow-up was 4.9 years. In 14 patients (40%), symptoms completely resolved; 14 (40%) had symptoms interfering with function but not with activities of daily living (ADLs; grade 2); seven (20%) had symptoms interfering with ADLs (grade 3). In 24 patients, radiologic follow-up was available; in six (25%), lesions improved/disappeared; in 13 (54%), lesions remained stable; five (21%) had progressive lesions.

Conclusion

Six percent of pediatric patients with ALL developed symptomatic osteonecrosis during or shortly after treatment. Older age and female sex were risk factors. After a median follow-up of 5 years, 60% of patients had persistent symptoms.

High concordance of subtypes of childhood acute lymphoblastic leukemia within families: lessons from sibships with multiple cases of leukemia

Polymorphic genes have been linked to the risk of acute lymphoblastic leukemia (ALL). Surrogate markers for a low burden of early childhood infections are also related to increased risk for developing childhood ALL. It remains uncertain, whether siblings of children with ALL have an increased risk of developing ALL. This international collaboration identified 54 sibships with two (N = 51) or more (N = 3) cases of childhood ALL (ages <18 years). The 5-year event-free survival for 61 patients diagnosed after 1 January 1990 was 0.83 ± 0.05. Ages at diagnosis (Spearman correlation coefficient, r(S) = 0.41, P = 0.002) were significantly correlated, but not WBCs (r(S) = 0.23, P = 0.11). In 18 sibships with successful karyotyping in both cases, six were concordant for high-hyperdiploidy (N = 3), t(12;21) [ETV6/RUNX1] (N = 1), MLL rearrangement (N = 1) or t(1;19)(q23/p13) (N = 1). Eleven sibships were ALL-subtype concordant, being T-cell ALL (T-ALL) (N = 5, of a total of six sibships, where the first-born had T-ALL) or B-lineage ALL belonging to the same cytogenetic subset (N = 6), a finding that differs significantly from the expected chance distribution (κ: 0.58; P < 0.0001). These data indicate strong genetic and/or environmental risk factors for childhood ALL that are restricted to specific ALL subtypes, which must be taken into account, when performing epidemiological studies to reveal etiological factors.

Oncogenic IL7R gain-of-function mutations in childhood T-cell acute lymphoblastic leukemia

Interleukin 7 (IL-7) and its receptor, formed by IL-7Rα (encoded by IL7R) and γc, are essential for normal T-cell development and homeostasis. Here we show that IL7R is an oncogene mutated in T-cell acute lymphoblastic leukemia (T-ALL). We find that 9% of individuals with T-ALL have somatic gain-of-function IL7R exon 6 mutations. In most cases, these IL7R mutations introduce an unpaired cysteine in the extracellular juxtamembrane-transmembrane region and promote de novo formation of intermolecular disulfide bonds between mutant IL-7Rα subunits, thereby driving constitutive signaling via JAK1 and independently of IL-7, γc or JAK3. IL7R mutations induce a gene expression profile partially resembling that provoked by IL-7 and are enriched in the T-ALL subgroup comprising TLX3 rearranged and HOXA deregulated cases. Notably, IL7R mutations promote cell transformation and tumor formation. Overall, our findings indicate that IL7R mutational activation is involved in human T-cell leukemogenesis, paving the way for therapeutic targeting of IL-7R-mediated signaling in T-ALL.