Heterogeneous MYCN amplification in neuroblastoma: a SIOP Europe Neuroblastoma Study

MYCN amplification and International Neuroblastoma Risk Group stratification on fine-needle aspiration biopsy and their correlation to survival in neuroblastoma

AIMS

Risk stratification as per the International Neuroblastoma Risk Group (INRG) stratification is important for management of neuroblastoma. INRG incorporates various parameters including histological category as per the International Neuroblastoma Pathology Classification (INPC) and MYCN amplification, which were evaluated in fine needle aspiration biopsy (FNAB) samples of neuroblastoma patients to ascertain their impact in our population.

METHODS

This was a retrospective study including 60 neuroblastoma cases diagnosed on FNAB, staged and stratified by INRG. Mitosis Karyorrhexis Index (MKI), INPC morphological category and MYCN status by fluorescence in situ hybridisation (n=46) were evaluated and correlated to outcome.

RESULTS

The mean age was 29 months (21 days to 9 years) with 27 and 33 children

CONCLUSION

FNAB is a complete modality for diagnosing neuroblastoma and providing all information required for risk stratification as per INRG including MKI, MYCN amplification, INPC category. Our cohort with predominant high-risk neuroblastoma cases highlights regional variation.

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Key Words

• FISH
• NEUROBLASTOMA
• Pathology, Molecular

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MESH Headings

• Child
• Child, Preschool
• Female
• Humans
• Infant
• Male
• Biopsy, Fine-Needle
• Gene Amplification
• N-Myc Proto-Oncogene Protein/genetics
• Neuroblastoma/genetics
• Neuroblastoma/pathology
• Prognosis
• Retrospective Studies
• Infant, Newborn

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Affiliation(s)

Neha Bhardwaj Pathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
Manish Rohilla Cytology & Gynecological Pathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
Amita Trehan Department of Pediatrics (Hematology-Oncology Division), Post Graduate Institute of Medical Education and Research, Chandigarh, India
Deepak Bansal Department of Pediatrics (Hematology-Oncology Division), Post Graduate Institute of Medical Education and Research, Chandigarh, India
Nandita Kakkar Histopathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
Radhika Srinivasan Cytology & Gynecological Pathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India

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Review: Targeting EZH2 in neuroblastoma

Neuroblastoma is one of the commonest extra-cranial pediatric tumors, and accounts for over 15% of all childhood cancer mortality. Risk stratification for children with neuroblastoma is based on age, stage, histology, and tumor cytogenetics. The majority of patients are considered to have high-risk neuroblastoma, for which the long-term survival is less than 50%. Current treatments combine surgical resection, chemotherapy, stem cell transplantation, radiotherapy, anti-GD2 based immunotherapy as well as the differentiating agent isotretinoin. Despite the intensive multimodal therapies applied, there are high relapse rates, and recurrent disease is often resistant to further therapy. Enhancer of Zeste Homolog 2 (EZH2), a catalytic subunit of Polycomb Repressive Complex 2 (PRC2), is a histone methyltransferase that represses transcription through trimethylation of lysine residue K27 on histone H3 (H3K27me3). It is responsible for epigenetic repression of transcription, making EZH2 an essential regulator for cell differentiation. Overexpression of EZH2 has been shown to promote tumorigenesis, cancer cell proliferation and prevent tumor cells from differentiating in a number of cancers. Therefore, research has been ongoing for the past decade, developing treatments that target EZH2 in neuroblastoma. This review summarises the role of EZH2 in neuroblastoma and evaluates the latest research findings on the therapeutic potential of targeting EZH2 in the treatment of neuroblastoma.

Single-cell transcriptomics and epigenomics unravel the role of monocytes in neuroblastoma bone marrow metastasis

Metastasis is the major cause of cancer-related deaths. Neuroblastoma (NB), a childhood tumor has been molecularly defined at the primary cancer site, however, the bone marrow (BM) as the metastatic niche of NB is poorly characterized. Here we perform single-cell transcriptomic and epigenomic profiling of BM aspirates from 11 subjects spanning three major NB subtypes and compare these to five age-matched and metastasis-free BM, followed by in-depth single cell analyses of tissue diversity and cell-cell interactions, as well as functional validation. We show that cellular plasticity of NB tumor cells is conserved upon metastasis and tumor cell type composition is NB subtype-dependent. NB cells signal to the BM microenvironment, rewiring via macrophage mgration inhibitory factor and midkine signaling specifically monocytes, which exhibit M1 and M2 features, are marked by activation of pro- and anti-inflammatory programs, and express tumor-promoting factors, reminiscent of tumor-associated macrophages. The interactions and pathways characterized in our study provide the basis for therapeutic approaches that target tumor-to-microenvironment interactions.

A light-operated dual-mode method for neuroblastoma diagnosis based on a Tb-MOF: from biometabolite detection to logic devices

Tb-DBA can not only serve as a light-operated dual-mechanism driven platform to detect VMA (an early pathological feature of neuroblastoma), but can also produce a different fluorescence response to epinephrine (EP, the metabolic precursor of VMA).

Gene expression-based dissection of inter-histotypes, intra-histotype and intra-tumor heterogeneity in pediatric tumors

Intra-tumor heterogeneity (ITH) fosters tumor evolution, resistance to therapy, and relapse. Recently, many evidence have been accumulated on the occurrence of genetic ITH in pediatric cancers. With this study we aimed to address the downstream effects that genetic and epigenetic ITH, and tumor-microenvironment interactions may produce within a tumor mass. To this aim, we investigated by high-throughput gene expression multiple samples of 5 hepatoblastomas, 5 neuroblastomas, 5 rhabdomyosarcomas, and 5 Wilms tumors. Principal component analysis, single sample hallmark gene sets analysis, and weighted gene co-expression network analysis were performed on gene expression data. We observed that the different tumors clustered by histotype, and then by case, and in addition, a variable degree of ITH was visible in all the investigated cases. The ITH highlighted in this study can represent a challenge in tumor treatment since we demonstrated that different druggable hallmarks and targets may be heterogeneously present within the same tumor mass, and this can potentially lead to therapeutic failure. Despite this heterogeneity, we could highlight some commonalities among the different histotypes investigated, supporting the feasibility to move in the clinic from a histotype-driven to a target-driven, sometimes agnostic, approach at least in some cases.

Tumoral heterogeneity in neuroblastoma

Neuroblastoma is a solid, neuroendocrine tumor with divergent clinical behavior ranging from asymptomatic to fatal. The diverse clinical presentations of neuroblastoma are directly linked to the high intra- and inter-tumoral heterogeneity it presents. This heterogeneity is strongly associated with therapeutic resistance and continuous relapses, often leading to fatal outcomes. The development of successful risk assessment and tailored treatment strategies lies in evaluating the extent of heterogeneity via the accurate genetic and epigenetic profiling of distinct cell subpopulations present in the tumor. Recent studies have focused on understanding the molecular mechanisms that drive tumoral heterogeneity in pursuing better therapeutic and diagnostic approaches. This review describes the cellular, genetic, and epigenetic aspects of neuroblastoma heterogeneity. In addition, we summarize the recent findings on three crucial factors that can lead to heterogeneity in solid tumors: the inherent diversity of the progenitor cells, the presence of cancer stem cells, and the influence of the tumor microenvironment.

Molecular Basis of Beckwith–Wiedemann Syndrome Spectrum with Associated Tumors and Consequences for Clinical Practice

Simple Summary

Beckwith–Wiedemann syndrome (BWS, OMIM 130650) is an inborn overgrowth disorder caused by molecular alterations in chromosome 11p15.5. These molecular changes affect so-called imprinted genes, i.e., genes which underlie a complex regulation which is linked to the parental origin of the gene copy. Thus, either the maternal gene copy is expressed or the paternal, but this balanced regulation is prone to disturbances. In fact, different types of molecular variants have been identified in BWS, resulting in a variable phenotype; thus, it was consented that the syndromic entity was extended to the Beckwith–Wiedemann spectrum (BWSp). Some molecular subgroups of BWSp are associated with an increased embryonic tumor risk and have different likelihoods for specific tumors. Therefore, the precise determination of the molecular subgroup is needed for precise monitoring and treatment, but the molecular diagnostic procedure has several limitations and challenges which have to be considered.

Abstract

Beckwith–Wiedemann syndrome (BWS, OMIM 130650) is a congenital imprinting condition with a heterogenous clinical presentation of overgrowth and an increased childhood cancer risk (mainly nephroblastoma, hepatoblastoma or neuroblastoma). Due to the varying clinical presentation encompassing classical, clinical BWS without a molecular diagnosis and BWS-related phenotypes with an 11p15.5 molecular anomaly, the syndromic entity was extended to the Beckwith–Wiedemann spectrum (BWSp). The tumor risk of up to 30% depends on the molecular subtype of BWSp with causative genetic or epigenetic alterations in the chromosomal region 11p15.5. The molecular diagnosis of BWSp can be challenging for several reasons, including the range of causative molecular mechanisms which are frequently mosaic. The molecular basis of tumor formation appears to relate to stalled cellular differentiation in certain organs that predisposes persisting embryonic cells to accumulate additional molecular defects, which then results in a range of embryonal tumors. The molecular subtype of BWSp not only influences the overall risk of neoplasia, but also the likelihood of specific embryonal tumors.

Targeted Analysis of Cell-free Circulating Tumor DNA is Suitable for Early Relapse and Actionable Target Detection in Patients with Neuroblastoma

PURPOSE

Treating refractory or relapsed neuroblastoma remains challenging. Monitoring body fluids for tumor-derived molecular information indicating minimal residual disease supports more frequent diagnostic surveillance and may have the power to detect resistant subclones before they give rise to relapses. If actionable targets are identified from liquid biopsies, targeted treatment options can be considered earlier.

EXPERIMENTAL DESIGN

Droplet digital PCR assays assessing MYCN and ALK copy numbers and allelic frequencies of ALK p.F1174L and ALK p.R1275Q mutations were applied to longitudinally collected liquid biopsies and matched tumor tissue samples from 31 patients with high-risk neuroblastoma. Total cell-free DNA (cfDNA) levels and marker detection were compared with data from routine clinical diagnostics.

RESULTS

Total cfDNA concentrations in blood plasma from patients with high-risk neuroblastoma were higher than in healthy controls and consistently correlated with neuron-specific enolase levels and lactate dehydrogenase activity but not with 123I-meta-iodobenzylguanidine scores at relapse diagnosis. Targeted cfDNA diagnostics proved superior for early relapse detection to all current diagnostics in 2 patients. Marker analysis in cfDNA indicated intratumor heterogeneity for cell clones harboring MYCN amplifications and druggable ALK alterations that were not detectable in matched tumor tissue samples in 17 patients from our cohort. Proof of concept is provided for molecular target detection in cerebrospinal fluid from patients with isolated central nervous system relapses.

CONCLUSIONS

Tumor-specific alterations can be identified and monitored during disease course in liquid biopsies from pediatric patients with high-risk neuroblastoma. This approach to cfDNA surveillance warrants further prospective validation and exploitation for diagnostic purposes and to guide therapeutic decisions.

The mutational spectrum of ATRX aberrations in neuroblastoma and the associated patient and tumor characteristics

Neuroblastoma is the most common extracranial solid tumor in children. The chromatin remodeler ATRX is frequently mutated in high‐risk patients with a poor prognosis. Although many studies have reported ATRX aberrations and the associated clinical characteristics in neuroblastoma, a comprehensive overview is currently lacking. In this study, we extensively characterize the mutational spectrum of ATRX aberrations in neuroblastoma tumors reported in previous studies and present an overview of patient and tumor characteristics. We collected the data of a total of 127 neuroblastoma patients and three cell lines with ATRX aberrations originating from 20 papers. We subdivide the ATRX aberrations into nonsense, missense, and multiexon deletions (MEDs) and show that 68% of them are MEDs. Of these MEDs, 75% are predicted to be in‐frame. Furthermore, we identify a missense mutational hotspot region in the helicase domain. We also confirm that all three ATRX mutation types are more often identified in patients diagnosed at an older age, but still approximately 40% of the patients are aged 5 years or younger at diagnosis. Surprisingly, we found that 11q deletions are enriched in neuroblastomas with ATRX deletions compared to a reference cohort, but not in neuroblastomas with ATRX point mutations. Taken together, our data emphasizes a distinct ATRX mutation spectrum in neuroblastoma, which should be considered when studying molecular phenotypes and therapeutic strategies.

Biological significance of MYC and CEBPD coamplification in urothelial carcinoma: Multilayered genomic, transcriptional and posttranscriptional positive feedback loops enhance oncogenic glycolysis

BACKGROUND AND PURPOSE

The aim of this study is to decipher the underlying mechanisms of CCAAT/enhancer-binding protein delta (CEBPD)-enhanced glycolysis as well as the biological significance of CEBPD and MYC coamplification in urothelial carcinoma (UC).

METHODS

In vitro analyses were conducted to examine the effects of altered CEBPD or MYC expression on UC cells. The in vivo effects of CEBPD overexpression in a high-glucose environment on tumour growth were investigated in xenografted induced diabetic severe combined immunodeficiency/beige mice. Data mining was used to cross-validate the associations between CEBPD and MYC copy number and transcriptional expression, quantitative reverse transcription-polymerase chain reaction, immunohistochemistry, chromogenic in situ hybridization, and in situ hybridization targeting microRNA were performed on 635 UC patient samples and xenograft samples. UC patient survival in relation to diabetes was validated by using the National Health Insurance Research Database.

RESULTS

CEBPD and MYC coamplification (29.6%) occurred at a high frequency, MYC expression promoted chromosomal instability, facilitating CEBPD copy number gain and expression. CEBPD promoted glucose uptake and lactate production by upregulating SLC2A1 and HK2, leading to mitochondrial fission, increased extracellular acidification rate and decreased oxygen consumption rate to fuel cell growth. CEBPD upregulated HK2 expression through multiple regulation pathways including MYC stabilization, suppression of FBXW7 transactivation and MYC-independent transcriptional suppression of hsa-miR-429. Clinical and xenografted experiments confirmed the growth advantage of CEBPD in relation to glucose metabolic dysregulation and the significant correlations between the expression of these genes.

CONCLUSIONS

We confirmed that CEBPD has an oncogenic role in UC by activating AKT signalling and initiating metabolic reprogramming from mitochondrial oxidative phosphorylation to glycolysis to satisfy glucose addiction. These novel CEBPD- and MYC-centric multilayered positive feedback loops enhance cancer growth that could complement theranostic approaches.

Intra-Tumour Genetic Heterogeneity and Prognosis in High-Risk Neuroblastoma

Spatial ITH is defined by genomic and biological variations within a tumour acquired by tumour cell evolution under diverse microenvironments, and its role in NB patient prognosis is understudied. In this work, we applied pangenomic techniques to detect chromosomal aberrations in at least two different areas of each tumour and/or in simultaneously obtained solid and liquid biopsies, detecting ITH in the genomic profile of almost 40% of HR-NB. ITH was better detected when comparing one or more tumour pieces and liquid biopsy (50%) than between different tumour pieces (21%). Interestingly, we found that patients with ITH analysed by pangenomic techniques had a significantly better survival rate that those with non-heterogeneous tumours, especially in cases without MYCN amplification. Moreover, all patients in the studied cohort with high ITH (defined as 50% or more genomic aberration differences between areas of a tumour or simultaneously obtained samples) survived after 48 months. These results clearly support analysing at least two solid tumour areas (separately or mixed) and liquid samples to provide more accurate genomic diagnosis, prognosis and therapy options in HR-NB.

Radiogenomics prediction for MYCN amplification in neuroblastoma: A hypothesis generating study

BACKGROUND

MYCN amplification represents a powerful prognostic factor in neuroblastoma (NB) and may occasionally account for intratumoral heterogeneity. Radiomics is an emerging field of advanced image analysis that aims to extract a large number of quantitative features from standard radiological images, providing valuable clinical information.

PROCEDURE

In this retrospective study, we aimed to create a radiogenomics model by correlating computed tomography (CT) radiomics analysis with MYCN status. NB lesions were segmented on pretherapy CT scans and radiomics features subsequently extracted using a dedicated library. Dimensionality reduction/features selection approaches were then used for features procession and logistic regression models have been developed for the considered outcome.

RESULTS

Seventy-eight patients were included in this study, as training dataset, of which 24 presented MYCN amplification. In total, 232 radiomics features were extracted. Eight features were selected through Boruta algorithm and two features were lastly chosen through Pearson correlation analysis: mean of voxel intensity histogram (p = .0082) and zone size non-uniformity (p = .038). Five-times repeated three-fold cross-validation logistic regression models yielded an area under the curve (AUC) value of 0.879 on the training set. The model was then applied to an independent validation cohort of 21 patients, of which five presented MYCN amplification. The validation of the model yielded a 0.813 AUC value, with 0.85 accuracy on previously unseen data.

CONCLUSIONS

CT-based radiomics is able to predict MYCN amplification status in NB, paving the way to the in-depth analysis of imaging based biomarkers that could enhance outcomes prediction.

Frequency and Prognostic Impact of ALK Amplifications and Mutations in the European Neuroblastoma Study Group (SIOPEN) High-Risk Neuroblastoma Trial (HR-NBL1)

PURPOSE

In neuroblastoma (NB), the ALK receptor tyrosine kinase can be constitutively activated through activating point mutations or genomic amplification. We studied ALK genetic alterations in high-risk (HR) patients on the HR-NBL1/SIOPEN trial to determine their frequency, correlation with clinical parameters, and prognostic impact.

MATERIALS AND METHODS

Diagnostic tumor samples were available from 1,092 HR-NBL1/SIOPEN patients to determine ALK amplification status (n = 330), ALK mutational profile (n = 191), or both (n = 571).

RESULTS

Genomic ALK amplification (ALKa) was detected in 4.5% of cases (41 out of 901), all except one with MYCN amplification (MNA). ALKa was associated with a significantly poorer overall survival (OS) (5-year OS: ALKa [n = 41] 28% [95% CI, 15 to 42]; no-ALKa [n = 860] 51% [95% CI, 47 to 54], [P < .001]), particularly in cases with metastatic disease. ALK mutations (ALKm) were detected at a clonal level (> 20% mutated allele fraction) in 10% of cases (76 out of 762) and at a subclonal level (mutated allele fraction 0.1%-20%) in 3.9% of patients (30 out of 762), with a strong correlation between the presence of ALKm and MNA (P < .001). Among 571 cases with known ALKa and ALKm status, a statistically significant difference in OS was observed between cases with ALKa or clonal ALKm versus subclonal ALKm or no ALK alterations (5-year OS: ALKa [n = 19], 26% [95% CI, 10 to 47], clonal ALKm [n = 65] 33% [95% CI, 21 to 44], subclonal ALKm (n = 22) 48% [95% CI, 26 to 67], and no alteration [n = 465], 51% [95% CI, 46 to 55], respectively; P = .001). Importantly, in a multivariate model, involvement of more than one metastatic compartment (hazard ratio [HR], 2.87; P < .001), ALKa (HR, 2.38; P = .004), and clonal ALKm (HR, 1.77; P = .001) were independent predictors of poor outcome.

CONCLUSION

Genetic alterations of ALK (clonal mutations and amplifications) in HR-NB are independent predictors of poorer survival. These data provide a rationale for integration of ALK inhibitors in upfront treatment of HR-NB with ALK alterations.

Biological categories of neuroblastoma based on the international neuroblastoma pathology classification for treatment stratification

The International Neuroblastoma Pathology Classification (INPC), which distinguishes a favorable histology (FH) and an unfavorable histology (UH), is one of the most powerful prognostic factors in patients with neuroblastoma. FH that shows spontaneous regression or age-appropriate tumor differentiation/maturation, is common in infants and has mutual interaction with Schwann cells via the NGF/NTRK1 pathway and gain of whole chromosome 17. In contrast, UH is prevalent in older children and is molecularly heterogeneous. MYCN amplification is the most frequent genomic abnormality in tumors with UH. MYCN-amplified tumors demonstrate characteristic histology, the same as MYC-positive neuroblastoma. Chromosome 1pLOH is often associated with MYCN amplification, but on the other hand, chromosome 11qLOH rarely occurs in combination with MYCN amplification. 11qLOH has an inferior prognostic impact in UH without MYCN amplification. The high expression of ALK protein is a negative prognostic factor in both ALK mutated or amplified tumors and FH, but not in UH. Abnormal maintenance/elongation of telomeres; overexpression of telomerase reverse transcriptase (TERT) and the alternative lengthening of telomeres (ALT) phenotype due to ATRX mutation, are another molecular event in UH. The INPC, incorporating immunohistochemistry for MYCN, MYC, ALK, TERT and ATRX, represents a practical and implementable approach to create the biological category for the future management of patients with this unique disease.

Long-Term Outcome and Role of Biology within Risk-Adapted Treatment Strategies: The Austrian Neuroblastoma Trial A-NB94

Simple Summary

Neuroblastoma, the most common extracranial malignancy of childhood, shows a highly variable course of disease ranging from spontaneous regression or maturation into a benign tumor to an aggressive and intractable cancer in up to 60% of patients. To adapt treatment intensity, risk staging at diagnosis is of utmost importance. The A-NB94 trial was the first in Austria to stratify therapy intensity according to tumor staging, patient’s age, and MYCN amplification status, the latter being a biologic marker turning otherwise low-risk tumors into high-risk disease. Recent publications showed a prognostic impact of various genomic features including segmental chromosomal aberrations (SCAs). We retrospectively investigated the relevance of SCAs within this risk-adapted treatment strategy. The A-NB94 approach resulted in an excellent long-term survival for the majority of patients with acceptable long-term morbidity. An age- and stage-dependent frequency of SCAs was confirmed and SCAs should always be considered in future treatment decision making processes.

Abstract

We evaluated long-term outcome and genomic profiles in the Austrian Neuroblastoma Trial A-NB94 which applied a risk-adapted strategy of treatment (RAST) using stage, age and MYCN amplification (MNA) status for stratification. RAST ranged from surgery only to intensity-adjusted chemotherapy, single or multiple courses of high-dose chemotherapy (HDT) followed by autologous stem cell rescue depending on response to induction chemotherapy, and irradiation to the primary tumor site. Segmental chromosomal alterations (SCAs) were investigated retrospectively using multi- and pan-genomic techniques. The A-NB94 trial enrolled 163 patients. Patients with localized disease had an excellent ten-year (10y) event free survival (EFS) and overall survival (OS) of 99 ± 1% and 93 ± 2% whilst it was 80 ± 13% and 90 ± 9% for infants with stage 4S and for infants with stage 4 non-MNA disease both 83 ± 15%. Stage 4 patients either >12 months or ≤12 months but with MNA had a 10y-EFS and OS of 45 ± 8% and 47 ± 8%, respectively. SCAs were present in increasing frequencies according to stage and age: in 29% of localized tumors but in 92% of stage 4 tumors (p < 0.001), and in 39% of patients ≤ 12 months but in 63% of patients > 12 months (p < 0.001). RAST successfully reduced chemotherapy exposure in low- and intermediate-risk patients with excellent long-term results while the outcome of high-risk disease met contemporary trials.

Imbalance between genomic gain and loss identifies high-risk neuroblastoma patients with worse outcomes

Survival in high-risk neuroblastoma (HR-NB) patients remains poor despite multimodal treatment. We aimed to identify HR-NB patients with worse outcomes by analyzing the genomic instability derived from segmental chromosomal aberrations. We calculated 3 genomic instability indexes for primary tumor SNP array profiles from 127 HR-NB patients: (1) Copy number aberration burden (%gains_length+%losses_length), (2) copy number load (CNL) (%gains_length-%losses_length) and (3) net genomic load (NGL) (%gains_amount-%losses_amount). Tumors were classified according to positive or negative CNL and NGL genomic subtypes. The impact of the genomic instability indexes on overall survival (OS) was assessed with Cox regression. We identified 38% of HR-NB patients with poor 5-year OS. A negative CNL genomic background was related to poor prognosis in patients ≥18 months showing tumors with homogeneous MYCN amplification (9.5% survival probability, P < 0.05) and patients with non-MYCN amplified NB (18.8% survival probability related to >2.4% CNL, P < 0.01). A positive CNL genomic background was associated with worse outcome in patients with heterogeneous MYCN amplification (22.5% survival probability, P < 0.05). We conclude that characterizing a tumor genomic background according to predominance of genome gained or lost contributes toward improved outcome prediction and brings greater insight into the tumor biology of HR-NB patients.

Implementation of the plasma MYCN/NAGK ratio to detect MYCN amplification in patients with neuroblastoma

Detection of amplification of the MYCN gene is essential for determining optimal treatment and estimating prognosis of patients with neuroblastoma (NB). DNA FISH with neuroblastoma tissues or patient‐derived bone marrow cells is the standard clinical practice for the detection of MYCN amplification. As tumor cells may often be unavailable, we developed a method to detect MYCN amplification in the plasma of patients with neuroblastoma. Taking single‐copy NAGK DNA as reference, we used real‐time quantitative PCR (qPCR) to determine the MYCN/NAGK ratio in the plasma of 115 patients diagnosed with NB. An increased MYCN/NAGK ratio in the plasma was consistent with MYCN amplification as assessed by DNA FISH. The AUC for a MYCN/NAGK ratio equal to 6.965 was 0.943, with 86% sensitivity and 100% specificity. Beyond the threshold of 6.965, the MYCN/NAGK ratio correlated with a heavier tumor burden. Event‐free and overall survival of two years were significantly shortened in stage 4 patients with a MYCN/NAGK ratio higher than 6.965. Plasma MYCN/NAGK ratios increased in patients with progressive disease and relapse. Thus, we conclude that the determination of the plasma MYCN/NAGK ratio by qPCR is a noninvasive and reproducible method to measure MYCN amplification in patients with NB.

Multiplexed Quantification of Four Neuroblastoma DNA Targets in a Single Droplet Digital PCR Reaction

The detection and characterization of cell-free DNA (cfDNA) in peripheral blood from neuroblastoma patients may serve as a minimally invasive approach to liquid biopsy. Major challenges in the analysis of cfDNA purified from blood samples are small sample volumes and low cfDNA concentrations. Droplet digital PCR (ddPCR) is a technology suitable for analyzing low levels of cfDNA. Reported here are two quadruplexed ddPCR assay protocols that reliably quantify MYCN and ALK copy numbers in a single reaction together with the two reference genes, NAGK and AFF3, and accurately estimate ALK^F1174L (exon 23 position 3522, C>A) and ALK^R1275Q (exon 25 position 3824, G>A) mutant allele fractions using cfDNA as input. The separation of positive and negative droplets was optimized for detecting two targets in each ddPCR fluorescence channel by the adjustment of the probe and primer concentrations of each target molecule. The quadruplexed assays were validated using a panel of 10 neuroblastoma cell lines and paired blood plasma and primary neuroblastoma samples from nine patients. Accuracy and sensitivity thresholds in quadruplexed assays corresponded well with those from the respective duplexed assays. Presented are two robust quadruplexed ddPCR protocols applicable in the routine clinical setting and that require only minimal plasma volumes for the assessment of MYCN and ALK oncogene status.

Association of heterogeneous MYCN amplification with clinical features, biological characteristics and outcomes in neuroblastoma: A report from the Children's Oncology Group

PURPOSE

MYCN amplification (MNA) is associated with poor outcomes in neuroblastoma. Less is known about heterogeneous MNA within a tumour. We compared clinical characteristics, biologic features and clinical outcomes of patients with heterogeneous MNA to patients with either homogeneous MNA or MYCN wild-type tumours.

PATIENTS AND METHODS

In this retrospective cohort study, we categorized patients as having tumours with MYCN wild-type, homogeneous MNA (>20% amplified tumour cells) or heterogeneous MNA (≤20% amplified tumour cells). We used chi-squared or Fisher's exact tests to compare features between groups. We used log-rank tests and Cox models to compare event-free survival (EFS) and overall survival (OS) between groups.

RESULTS

MYCN status and heterogeneity status (if amplified) could be ascertained in diagnostic tumour samples from 5975 patients, including 57 (1%) with heterogeneous MNA, 981 (16.4%) with homogeneous MNA, and 4937 (82.6%) with MYCN wild-type tumours. Multiple clinical and biological features differed between patients with heterogeneous vs. homogeneous MNA, including enrichment for thoracic primary sites and paucity of 1p loss of heterozygosity with heterogeneous MNA (p < 0.0001). Importantly, EFS and OS were not significantly different between patients with heterogeneous vs. homogeneous MNA. Further, EFS and OS for patients with heterogeneous MNA were significantly inferior to patients with wild-type MYCN.

CONCLUSION

Although neuroblastomas with heterogeneous MNA demonstrate significantly different biological and clinical patterns compared with homogeneous MNA, prognosis is similar between the two groups. These results support current practice that treats patients with heterogeneous MNA similarly to patients with homogeneous MNA.

MYCN gene polymorphisms and Wilms tumor susceptibility in Chinese children

BACKGROUND

Wilms tumor, derived from embryonic cells, accounts for a large proportion of pediatric renal tumors. MYCN encoded by MYCN proto-oncogene, a member of the MYC family, is a BHLH transcription factor. It plays a critical role in tumorigenesis and predicts poor clinical outcomes in various types of cancer. However, the role of MYCN remained unclarified in Wilms tumor. In this study, we investigated the association between MYCN gene polymorphisms and Wilms tumor susceptibility.

METHODS

Four MYCN gene polymorphisms (rs57961569 G > A, rs9653226 T > C, rs13034994 A > G, and rs60226897 G > A) were genotyped in 183 cases and 603 controls. Adjusted odds ratios (AORs) and 95% confidence intervals (CIs) were calculated to evaluate the association between MYCN gene polymorphisms and Wilms tumor susceptibility.

RESULTS

Overall, no significant association was found for any of the four MYCN gene polymorphisms. Interestingly, in the stratification analysis, the rs57961569 was found to be associated with decreased Wilms tumor susceptibility in the children older than 18 months (AOR = 0.65, 95% CI = 0.42-1.00, P = .050). Moreover, older children carrying 2-4 risk genotypes were at increased risk of Wilms tumor (OR = 1.55, 95% CI = 1.001-2.40, P = .0497). Haplotype GCAA was shown to significantly increased Wilms tumor risk (AOR = 2.40, 95% CI = 1.12-5.14, P = .024).

CONCLUSION

Our study demonstrated that these MYCN gene polymorphisms might be low penetrant variants in Wilms tumor.

MYCN Amplified Relapse Following Resolution of MYCN Nonamplified 4S Neuroblastoma With Placental Involvement: A Case Report and Review of the Literature

Congenital neuroblastoma with placental involvement is exceptionally rare, but mortality is high. Detailed examination of placenta including MYCN amplification and segmental chromosomal aberrations should be performed in all suspected cases, as it is noninvasive and readily available. Maternal dissemination has not been reported. In this manuscript, we describe an infant with placental diagnosis of MYCN nonamplified congenital neuroblastoma. This is the first report of a recurrence of congenital 4S neuroblastoma following resolution in which MYCN amplification is only detected in the recurrence. Germline sequencing using a large comprehensive cancer panel did not reveal variants in candidate cancer predisposition genes.