Barbara Hero

The International Neuroblastoma Risk Group (INRG) Classification System: An INRG Task Force Report

PURPOSE Because current approaches to risk classification and treatment stratification for children with neuroblastoma (NB) vary greatly throughout the world, it is difficult to directly compare risk-based clinical trials. The International Neuroblastoma Risk Group (INRG) classification system was developed to establish a consensus approach for pretreatment risk stratification. PATIENTS AND METHODS The statistical and clinical significance of 13 potential prognostic factors were analyzed in a cohort of 8,800 children diagnosed with NB between 1990 and 2002 from North America and Australia (Childrens Oncology Group), Europe (International Society of Pediatric Oncology Europe Neuroblastoma Group and German Pediatric Oncology and Hematology Group), and Japan. Survival tree regression analyses using event-free survival (EFS) as the primary end point were performed to test the prognostic significance of the 13 factors. RESULTS Stage, age, histologic category, grade of tumor differentiation, the status of the MYCN oncogene, chromosome 11q status, and DNA ploidy were the most highly statistically significant and clinically relevant factors. A new staging system (INRG Staging System) based on clinical criteria and tumor imaging was developed for the INRG Classification System. The optimal age cutoff was determined to be between 15 and 19 months, and 18 months was selected for the classification system. Sixteen pretreatment groups were defined on the basis of clinical criteria and statistically significantly different EFS of the cohort stratified by the INRG criteria. Patients with 5-year EFS more than 85%, more than 75% to < or = 85%, > or = 50% to < or = 75%, or less than 50% were classified as very low risk, low risk, intermediate risk, or high risk, respectively. CONCLUSION By defining homogenous pretreatment patient cohorts, the INRG classification system will greatly facilitate the comparison of risk-based clinical trials conducted in different regions of the world and the development of international collaborative studies.

Myeloablative megatherapy with autologous stem-cell rescue versus oral maintenance chemotherapy as consolidation treatment in patients with high-risk neuroblastoma: a randomised controlled trial

BACKGROUND Myeloablative megatherapy is commonly used to improve the poor outlook of children with high-risk neuroblastoma, yet its role is poorly defined. We aimed to assess whether megatherapy with autologous stem-cell transplantation could increase event-free survival and overall survival compared with maintenance chemotherapy. METHODS 295 patients with high-risk neuroblastoma (ie, patients with stage 4 disease aged older than 1 year or those with MYCN-amplified tumours and stage 1, 2, 3, or 4S disease or stage 4 disease and <1 year old) were randomly assigned to myeloablative megatherapy (melphalan, etoposide, and carboplatin) with autologous stem-cell transplantation (n=149) or to oral maintenance chemotherapy with cyclophosphamide (n=146). The primary endpoint was event-free survival. Secondary endpoints were overall survival and the number of treatment-related deaths. Analyses were done by intent to treat, as treated, and treated as randomised. FINDINGS Intention-to-treat analysis showed that patients allocated megatherapy had increased 3-year event-free survival compared with those allocated maintenance therapy (47% [95% CI 38-55] vs 31% [95% CI 23-39]; hazard ratio 1.404 [95% CI 1.048-1.881], p=0.0221), but did not have significantly increased 3-year overall survival (62% [95% CI 54-70] vs 53% [95% CI 45-62]; 1.329 [0.958-1.843], p=0.0875). Improved 3-year event-free survival and 3-year overall survival were also recorded for patients given megatherapy in the as-treated group (n=212) and in the treated-as-randomised group (n=145). Two patients died from therapy-related complications during induction treatment. No patients given maintenance therapy died from acute treatment-related toxic effects. Five patients given megatherapy died from acute complications related to megatherapy. INTERPRETATION Myeloablative chemotherapy with autologous stem-cell transplantation improves the outcome for children with high-risk neuroblastoma despite the raised risk of treatment-associated death.

Customized Oligonucleotide Microarray Gene Expression–Based Classification of Neuroblastoma Patients Outperforms Current Clinical Risk Stratification

PURPOSE To develop a gene expression-based classifier for neuroblastoma patients that reliably predicts courses of the disease. PATIENTS AND METHODS Two hundred fifty-one neuroblastoma specimens were analyzed using a customized oligonucleotide microarray comprising 10,163 probes for transcripts with differential expression in clinical subgroups of the disease. Subsequently, the prediction analysis for microarrays (PAM) was applied to a first set of patients with maximally divergent clinical courses (n = 77). The classification accuracy was estimated by a complete 10-times-repeated 10-fold cross validation, and a 144-gene predictor was constructed from this set. This classifiers predictive power was evaluated in an independent second set (n = 174) by comparing results of the gene expression-based classification with those of risk stratification systems of current trials from Germany, Japan, and the United States. RESULTS The first set of patients was accurately predicted by PAM (cross-validated accuracy, 99%). Within the second set, the PAM classifier significantly separated cohorts with distinct courses (3-year event-free survival [EFS] 0.86 +/- 0.03 [favorable; n = 115] v 0.52 +/- 0.07 [unfavorable; n = 59] and 3-year overall survival 0.99 +/- 0.01 v 0.84 +/- 0.05; both P < .0001) and separated risk groups of current neuroblastoma trials into subgroups with divergent outcome (NB2004: low-risk 3-year EFS 0.86 +/- 0.04 v 0.25 +/- 0.15, P < .0001; intermediate-risk 1.00 v 0.57 +/- 0.19, P = .018; high-risk 0.81 +/- 0.10 v 0.56 +/- 0.08, P = .06). In a multivariate Cox regression model, the PAM predictor classified patients of the second set more accurately than risk stratification of current trials from Germany, Japan, and the United States (P < .001; hazard ratio, 4.756 [95% CI, 2.544 to 8.893]). CONCLUSION Integration of gene expression-based class prediction of neuroblastoma patients may improve risk estimation of current neuroblastoma trials.

Neuroblastoma: biology and molecular and chromosomal pathology

Neuroblastoma is the most frequently occurring solid tumour in children, with an incidence of 1.3 cases per 100000 children aged 0-14 years. Despite many advances during the past three decades, neuroblastoma has remained an enigmatic challenge to clinical and basic scientists. 20 years ago, the MYCN gene was found to be amplified in neuroblastomas, and research since then has focused on the search for other genetic markers. It has emerged that neuroblastoma cells, like cells of many other tumour types, often suffer from extensive, non-random genetic damage at multiple genetic loci. Elucidation of the exact molecular make-up of neuroblastomas will enable researchers to analyse how much specific markers, alone or in combination, can help to stratify disease in prospective studies; at present, stratification is based on age, stage, MYCN, and Shimada pathology. Neuroblastoma may be one of the first examples of the use of genetic tumour markers as a tool for defining tumour behaviour and to aid clinical staging.

Histone deacetylase 8 in neuroblastoma tumorigenesis

Purpose: The effects of pan–histone deacetylase (HDAC) inhibitors on cancer cells have shown that HDACs are involved in fundamental tumor biological processes such as cell cycle control, differentiation, and apoptosis. However, because of the unselective nature of these compounds, little is known about the contribution of individual HDAC family members to tumorigenesis and progression. The purpose of this study was to evaluate the role of individual HDACs in neuroblastoma tumorigenesis. Experimental Design: We have investigated the mRNA expression of all HDAC1-11 family members in a large cohort of primary neuroblastoma samples covering the full spectrum of the disease. HDACs associated with disease stage and survival were subsequently functionally evaluated in cell culture models. Results: Only HDAC8 expression was significantly correlated with advanced disease and metastasis and down-regulated in stage 4S neuroblastoma associated with spontaneous regression. High HDAC8 expression was associated with poor prognostic markers and poor overall and event-free survival. The knockdown of HDAC8 resulted in the inhibition of proliferation, reduced clonogenic growth, cell cycle arrest, and differentiation in cultured neuroblastoma cells. The treatment of neuroblastoma cell lines as well as short-term-culture neuroblastoma cells with an HDAC8-selective small-molecule inhibitor inhibited cell proliferation and clone formation, induced differentiation, and thus reproduced the HDAC8 knockdown phenotype. Global histone 4 acetylation was not affected by HDAC8 knockdown or by selective inhibitor treatment. Conclusions: Our data point toward an important role of HDAC8 in neuroblastoma pathogenesis and identify this HDAC family member as a specific drug target for the differentiation therapy of neuroblastoma.

Localized infant neuroblastomas often show spontaneous regression: results of the prospective trials NB95-S and NB97.

PURPOSE The excellent prognosis of localized neuroblastoma in infants, the overdiagnosis observed in neuroblastoma screening studies, and several case reports of regression of localized neuroblastoma prompted us to initiate a prospective cooperative trial on observation of localized neuroblastoma without cytotoxic treatment. PATIENTS AND METHODS For infants with localized neuroblastoma without MYCN amplification, chemotherapy was scheduled only in cases with threatening symptoms; otherwise, the tumor was either resected or observed by ultrasound and magnetic resonance imaging (MRI). RESULTS Of 340 eligible participants, 190 underwent resection, 57 were treated with chemotherapy, and 93 were observed with gross residual tumor. Of those 93 patients with unresected tumors, spontaneous regression was seen in 44, local progression in 28, progression to stage 4S in seven, and progression to stage 4 in four. Time to regression was quite variable, with first signs of regression noted 1 to 18 months after diagnosis and in 15 of 44 patients even after the first year of life. So far, complete regression was observed in 17 of 44 patients 4 to 20 months after diagnosis. Known clinical risk factors were not able to differentiate between patients with regression and regional or metastatic progression. Overall survival (OS; 3-year OS, 0.99 +/- 0.01) and metastases-free survival (rate at 3 years, 0.94 +/- 0.03) for patients with unresected tumors was excellent and was not different from patients treated with surgery or chemotherapy. CONCLUSION Spontaneous regression is regularly seen in infants with localized neuroblastoma and is not limited to the first year of life. A wait-and-see strategy is justified in those patients.

Distinct transcriptional MYCN/c-MYC activities are associated with spontaneous regression or malignant progression in neuroblastomas

BackgroundAmplified MYCN oncogene resulting in deregulated MYCN transcriptional activity is observed in 20% of neuroblastomas and identifies a highly aggressive subtype. In MYCN single-copy neuroblastomas, elevated MYCN mRNA and protein levels are paradoxically associated with a more favorable clinical phenotype, including disseminated tumors that subsequently regress spontaneously (stage 4s-non-amplified). In this study, we asked whether distinct transcriptional MYCN or c-MYC activities are associated with specific neuroblastoma phenotypes.ResultsWe defined a core set of direct MYCN/c-MYC target genes by applying gene expression profiling and chromatin immunoprecipitation (ChIP, ChIP-chip) in neuroblastoma cells that allow conditional regulation of MYCN and c-MYC. Their transcript levels were analyzed in 251 primary neuroblastomas. Compared to localized-non-amplified neuroblastomas, MYCN/c-MYC target gene expression gradually increases from stage 4s-non-amplified through stage 4-non-amplified to MYCN amplified tumors. This was associated with MYCN activation in stage 4s-non-amplified and predominantly c-MYC activation in stage 4-non-amplified tumors. A defined set of MYCN/c-MYC target genes was induced in stage 4-non-amplified but not in stage 4s-non-amplified neuroblastomas. In line with this, high expression of a subset of MYCN/c-MYC target genes identifies a patient subtype with poor overall survival independent of the established risk markers amplified MYCN, disease stage, and age at diagnosis.ConclusionsHigh MYCN/c-MYC target gene expression is a hallmark of malignant neuroblastoma progression, which is predominantly driven by c-MYC in stage 4-non-amplified tumors. In contrast, moderate MYCN function gain in stage 4s-non-amplified tumors induces only a restricted set of target genes that is still compatible with spontaneous regression.

Consolidation Treatment With Chimeric Anti-GD2-Antibody ch14.18 in Children Older Than 1 Year With Metastatic Neuroblastoma

PURPOSE Antibody treatment is considered tolerable and potentially effective in the therapy of neuroblastoma. We have analyzed stage 4 neuroblastoma patients older than 1 year who underwent consolidation treatment with the chimeric monoclonal anti-GD2-antibody ch14.18. PATIENTS AND METHODS Stage 4 patients older than 1 year who completed initial treatment without event were eligible. ch14.18 was scheduled in a dose of 20 mg/m2/d during 5 days in six cycles every 2 months. Patients who did not receive ch14.18 served as controls. RESULTS Of 334 assessable patients, 166 received ch14.18, 99 received a 12-month low-dose maintenance chemotherapy (MT) instead, and 69 had no additional treatment. During 695 ch14.18 cycles, fever (55% of cycles), abnormal C-reactive protein without infection (35%), cough (24%), rash (22%), and pain (16%) were the main side effects. Univariate analysis found similar event-free survival (EFS) for the three groups (3-year EFS, 46.5% +/- 4.1%, 44.4% +/- 4.9%, 37.1% +/- 5.9% for patients treated with antibody ch14.18, MT, and no additional therapy, respectively; log-rank test, P =.314). For overall survival (OS), ch14.18 treatment (3-year OS, 68.5% +/- 3.9%) was superior to MT (3-year OS, 56.6% +/- 5.0%) or no additional therapy (3-year OS, 46.8% +/- 6.2%; log-rank test, P =.018). Separate univariate analysis of patients with autologous stem-cell transplantation revealed no difference between patients with ch14.18 treatment and no additional consolidation. Multivariate analysis failed to demonstrate an advantage of antibody treatment for EFS and OS. CONCLUSION Consolidation treatment of stage 4 neuroblastoma with ch14.18 was associated with considerable but manageable side effects. Compared with oral maintenance chemotherapy and no consolidation treatment, ch14.18 had no clear impact on the outcome of patients.

Telomerase activation by genomic rearrangements in high-risk neuroblastoma

Neuroblastoma is a malignant paediatric tumour of the sympathetic nervous system. Roughly half of these tumours regress spontaneously or are cured by limited therapy. By contrast, high-risk neuroblastomas have an unfavourable clinical course despite intensive multimodal treatment, and their molecular basis has remained largely elusive. Here we have performed whole-genome sequencing of 56 neuroblastomas (high-risk, n = 39; low-risk, n = 17) and discovered recurrent genomic rearrangements affecting a chromosomal region at 5p15.33 proximal of the telomerase reverse transcriptase gene (TERT). These rearrangements occurred only in high-risk neuroblastomas (12/39, 31%) in a mutually exclusive fashion with MYCN amplifications and ATRX mutations, which are known genetic events in this tumour type. In an extended case series (n = 217), TERT rearrangements defined a subgroup of high-risk tumours with particularly poor outcome. Despite a large structural diversity of these rearrangements, they all induced massive transcriptional upregulation of TERT. In the remaining high-risk tumours, TERT expression was also elevated in MYCN-amplified tumours, whereas alternative lengthening of telomeres was present in neuroblastomas without TERT or MYCN alterations, suggesting that telomere lengthening represents a central mechanism defining this subtype. The 5p15.33 rearrangements juxtapose the TERT coding sequence to strong enhancer elements, resulting in massive chromatin remodelling and DNA methylation of the affected region. Supporting a functional role of TERT, neuroblastoma cell lines bearing rearrangements or amplified MYCN exhibited both upregulated TERT expression and enzymatic telomerase activity. In summary, our findings show that remodelling of the genomic context abrogates transcriptional silencing of TERT in high-risk neuroblastoma and places telomerase activation in the centre of transformation in a large fraction of these tumours.

The Tumor-Associated Antigen PRAME Is Universally Expressed in High-Stage Neuroblastoma and Associated with Poor Outcome

Purpose: The tumor-associated antigen PRAME, a potential candidate for immunotherapeutic targeting, is frequently expressed in a variety of cancers. However, no information about its presence in neuroblastoma is available to date. We therefore evaluated and quantified PRAME expression in a considerable number of neuroblastoma tumors and assessed its impact on the outcome of patients. Experimental Design: Qualitative analysis of PRAME expression was assessed by reverse transcription (RT)-PCR screening of 94 patients with primary neuroblastoma. The same cohort was used for semiquantitative determination of transcript levels by Northern blotting, comparing the signal intensities of patients with those of testis total RNA. For more precise quantification of PRAME expression, real-time RT-PCR was performed in 88 patients of the above cohort and 7 additional patients, thus leaving a total of 101 patients that were analyzed with either method. Furthermore, association with tumor stage, age of patients at diagnosis, and MYCN amplification was determined as well as the prognostic impact of PRAME expression. Results: RT-PCR screening detected PRAME expression in 93% of primary neuroblastoma and 100% of patients with advanced disease. Furthermore, RT-PCR and Northern blot analysis showed a highly significant association of PRAME expression with both higher tumor stage (P < 0.01) and the age of patients at diagnosis (P < 0.01). Finally, precise quantification of PRAME expression by quantitative real-time reverse transcription-PCR displayed significant impact on the outcome of patients. Conclusions: PRAME expression in neuroblastoma is extraordinarily common and was universally seen in patients with advanced-stage disease in our study. Furthermore, significant impact of PRAME expression on the outcome of patients was shown. Thus, PRAME may present a particularly attractive target for immunotherapeutic strategies in neuroblastoma.