Role of surgery in neuroblastoma

Neuroblastoma is the most common malignant solid tumor handled by pediatric surgeons. It is well-known that neuroblastoma shows variable biological and clinical behaviors. In this review article, surgical strategy in neuroblastoma was described by risk stratification. Also, strategy of biopsy and clinical conditions that require special considerations such as neuroblastoma detected by mass screening, relapsed neuroblastoma, patients with stage MS and dumbbell type tumors was mentioned. As multimodal systemic treatments have been expanding, the role of surgery in neuroblastoma has become relatively less significant but requisite. We surgeons should decide therapeutic strategy based on the correct understanding of biology of neuroblastoma thinking of the better future of children.

Plasma circulating cell-free MYCN gene: A noninvasive and prominent recurrence monitoring indicator of neuroblastoma

The postoperative recurrence of neuroblastoma (NB) patients is an essential reason for the high mortality of NB due to the lack of early, non-invasive, and dynamic strategies for monitoring NB recurrence. Therefore, whether the plasma circulating cell-free MYCN gene as an indicator for monitoring of NB recurrence was systematically evaluated. The MYCN copy number and NAGK (reference gene) copy number (M/N) ratio in plasma and corresponding tumor tissues of NB patients was detected using an economical, sensitive, and specific single-tube dual RT-PCR approach developed in this study. The plasma M/N ratio of the MYCN gene amplification (MNA) group (N = 25, median M/N ratio = 4.90) was significantly higher than that of the non-MNA group (N = 71, median M/N ratio = 1.22), p < .001. The M/N ratio in NB plasma (N = 60) was positively correlated with the M/N ratio in NB tumor tissue (N = 60), with a correlation coefficient of 0.9496. In particular, the results of dynamic monitoring of postoperative plasma M/N ratio of NB patients showed that an abnormal increase in M/N ratio could be detected 1-2 months before recurrence in NB patients. In summary, the single-tube double RT-PCR approach can be used to quantitatively detect MYCN copy number. The copy number of MYCN in the tissue and plasma of NB patients is consistent with each other. More importantly, the circulating cell-free MYCN gene of NB patients can be used as a monitoring indicator for early, non-invasive, and dynamic monitoring of NB recurrence.

Dual isothermal amplification all-in-one approach for rapid and highly sensitive quantification of plasma circulating MYCN gene of neuroblastoma

A dual isothermal amplification assay with dual fluorescence signal detection strategy, named dual isothermal amplification all-in-one approach, was developed for rapid, one-step, highly sensitive quantification of plasma circulating MYCN copy number of neuroblastoma (NB). The developed strategy consisted of rolling circle amplification (RCA) and loop-mediated isothermal amplification (LAMP) on a real-time PCR system using highly specific probe, molecular beacon (MB), as detection probe. The developed strategy possessing a broad linear dynamic range of 10 aM to 1 pM for both target gene (MYCN) and reference gene (NAGK). The ratio of the MYCN copy number to NAGK copy number (M/N ratio) was detected by the developed approach in cell lines, NB tumor tissues, hepatoblastoma tumor tissues and Wilms' tumor tissues, to which the M/N ratios were consistent with previous reports. In particular, the M/N ratio in NB clinical tissue specimens and NB plasma specimens detected with the developed approach were in keeping with the standard RT-PCR approach. More importantly, the M/N ratio in NB tissue samples and corresponding plasma samples of NB patients were consistent with each other with a correlation coefficient of 0.9690, indicating that plasma circulating MYCN is a promising indicator for the risk classification of NB.

MYCN Impact on High-Risk Neuroblastoma: From Diagnosis and Prognosis to Targeted Treatment

Simple Summary

Neuroblastoma is one of the most diffuse and the deadliest cancer in children. While many advances have been made in the last few decades to improve patients’ outcome, high-risk neuroblastoma (HR-NB) still shows a very aggressive pattern of development and poor prognosis, with only a 50% chance of 5-year survival. Moreover, while many factors contribute to defining the high-risk condition, MYCN status is well established as the major element in pathology disclosure. The aim of this review is to describe the current knowledge in the diagnosis, prognosis and therapeutic approaches of HR-NB, particularly in relation to MYCN. The review highlights how MYCN influences the HR-NB scenario and the new therapeutic approaches that are currently proposed to target it, in consideration of MYCN as a highly relevant target for HR-NB patient management.

Abstract

Among childhood cancers, neuroblastoma is the most diffuse solid tumor and the deadliest in children. While to date, the pathology has become progressively manageable with a significant increase in 5-year survival for its less aggressive form, high-risk neuroblastoma (HR-NB) remains a major issue with poor outcome and little survivability of patients. The staging system has also been improved to better fit patient needs and to administer therapies in a more focused manner in consideration of pathology features. New and improved therapies have been developed; nevertheless, low efficacy and high toxicity remain a staple feature of current high-risk neuroblastoma treatment. For this reason, more specific procedures are required, and new therapeutic targets are also needed for a precise medicine approach. In this scenario, MYCN is certainly one of the most interesting targets. Indeed, MYCN is one of the most relevant hallmarks of HR-NB, and many studies has been carried out in recent years to discover potent and specific inhibitors to block its activities and any related oncogenic function. N-Myc protein has been considered an undruggable target for a long time. Thus, many new indirect and direct approaches have been discovered and preclinically evaluated for the interaction with MYCN and its pathways; a few of the most promising approaches are nearing clinical application for the investigation in HR-NB.

Targeted parallel DNA sequencing detects circulating tumor-associated variants of the mitochondrial and nuclear genomes in patients with neuroblastoma

BACKGROUND

The utility for liquid biopsy of tumor-associated circulating single-nucleotide variants, as opposed to mutations, of the mitochondrial (mt) and nuclear genomes in neuroblastoma (NB) is unknown.

PROCEDURE

Variants of the mt and nuclear genomes from tumor, blood cells, and consecutive plasma samples of five patients with metastatic NB that relapsed or progressed were analyzed. Targeted parallel sequencing results of the mt genome, and of the coding region of 139 nuclear genes and 22 miRNAs implicated in NB, were correlated with clinical imaging and laboratory data.

RESULTS

All tumors harbored multiple somatic mt and nuclear single nucleotide variants with low allelic frequency, most of them not detected in the circulation. In one patient a tumor-associated mt somatic variant was detected in the plasma before and during progressive disease. In a second patient a circulating nuclear tumor-associated DNA variant heralded clinical relapse. In all patients somatic mt and nuclear variants not evident in the tumor biopsy at time of diagnosis were found circulating at varying timepoints. This suggests either tumor heterogeneity, evolution of tumor variants or a confounding contribution of normal tissues to somatic variants in patient plasma. The number and allelic frequency of the circulating variants did not reflect the clinical course of the tumors. Mutational signatures of mt and nuclear somatic variants differed. They varied between patients and were detected in the circulation without mirroring the patients' course.

CONCLUSIONS

In this limited cohort of NB patients clinically informative tumor-associated mt and nuclear circulating variants were detected by targeted parallel sequencing in a minority of patients.

Quantitative assessment of copy number alterations by liquid biopsy for neuroblastoma

Liquid biopsy, a method of detecting genomic alterations using blood specimens, has recently attracted attention as a non-invasive alternative to surgical tissue biopsy. We attempted quantitative analysis to detect amplification of MYCN (MYCNamp) and loss of heterozygosity at 11q (11qLOH), which are clinical requisites as prognostic factors of neuroblastoma. In this study, cell-free DNA (cfDNA) was extracted from plasma samples from 24 neuroblastoma patients at diagnosis. Copy numbers of MYCN and NAGK genes were quantitatively analyzed by droplet digital PCR (ddPCR). 11qLOH was also assessed by detecting allelic imbalances of heterozygous single nucleotide polymorphisms in the 11q region. The results obtained were compared to those of specimens from tumor tissues. The correlation coefficient of MYCN copy number of cfDNA and tumor DNA was 0.88 (P < 0.00001). 11qLOH was also accurately detected from cfDNA, except for one case with localized NB. Given the high accuracy of liquid biopsy, to investigate components of cfDNA, the proportion of tumor-derived DNA was estimated by examining the variant allele frequency of tumor-specific mutations in cfDNA. The proportion of tumor-derived DNA in cfDNA was 42.5% (range, 16.9%-55.9%), suggesting sufficient sensitivity of liquid biopsy for neuroblastoma. In conclusion, MYCN copy number and 11qLOH could be quantitatively analyzed in plasma cfDNA by ddPCR assay. These results suggest that plasma cfDNA can be substituted for tumor DNA and can also be applied for comprehensive genomic profiling analysis. This article is protected by copyright. All rights reserved.

Extracellular Vesicle-Based Method for Detecting MYCN Amplification Status of Pediatric Neuroblastoma

Simple Summary

MYCN gene amplification, the strongest prognostic marker of aggressive neuroblastoma, is detected on invasive biopsy tissues. This study aimed to establish a less invasive method to detect MYCN status based on MYCN mRNA contents in large extracellular vesicles or microvesicles. MYCN mRNA-containing microvesicles were detectable in three distinct MYCN-amplified neuroblastoma cell lines but absent in three neuroblastoma cells with MYCN-non-amplification. The feasibility of this EV-based workflow was successfully demonstrated by using the simulated samples (prepared by pulsing neuroblastoma MVs into the normal human serum) and bone marrow plasma specimens obtained from nine patients at various disease stages. Taken together, this study established the novel EV-based method for detecting MYCN status in pediatric neuroblastoma.

Abstract

MYCN amplification is the strongest predictor of high-risk neuroblastoma (NB). The standard procedure to detect MYCN status requires invasive procedures. Extracellular vesicles (EVs) contain molecular signatures of originated cells, present in biofluids, and serve as an invaluable source for cancer liquid biopsies. This study aimed to establish an EV-based method to detect the MYCN status of NB. Two EV subtypes, i.e., microvesicles (MVs) and exosomes, were sequentially isolated from the culture supernatant by step-wise centrifugation, ultrafiltration, and size-exclusion chromatography. Quantitative RT-PCR was performed to detect MYCN mRNA. As a result, MYCN mRNA was detectable in the MVs, but not exosomes, of MYCN-amplified NB cells. MYCN mRNA-containing MVs (MYCN-MV) were successfully detected in three distinct MYCN-amplified NB cell lines but absent in three MYCN non-amplification cells. The simulated samples were prepared by pulsing MVs into human serum. MYCN–MV detection in the simulated samples showed a less interfering effect from the human blood matrix. Validation using clinical specimens (2 mL bone marrow plasma) obtained from patients at various disease stages showed a promising result. Five out of six specimens of MYCN-amplified patients showed positive results, while there were no false positives in four plasma samples of the MYCN non-amplification group. This study communicated a novel EV-based method for detecting the MYCN status of pediatric NB based on MYCN mRNA contents in MVs. Future studies should be pursued in a prospective cohort to determine its true diagnostic performance.

Recent clinical research on the application of liquid biopsy in neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid tumor in children and has the features of high recurrence rate and low survival rate, and therefore, early diagnosis, treatment response evaluation, and recurrence monitoring are of great significance for NB patients. Liquid biopsy refers to the detection of cells and nucleic acids in fluid specimens, mainly blood. It is noninvasive and can overcome tumor heterogeneity, thus making it possible to achieve the early diagnosis and dynamic detection of NB. This review introduces the latest advances in clinical research on the application of liquid biopsy in NB.

The feasibility of using liquid biopsies as a complementary assay for copy number aberration profiling in routinely collected paediatric cancer patient samples

BACKGROUND

Paediatric tumours are often characterised by the presence of recurrent DNA copy number alterations (CNAs). These DNA copy number profiles, obtained from a tissue biopsy, can aid in the correct prognostic classification and therapeutic stratification of several paediatric cancer entities (e.g. MYCN amplification in neuroblastoma) and are part of the routine diagnostic practice. Liquid biopsies (LQBs) offer a potentially safer alternative for such invasive tumour tissue biopsies and can provide deeper insight into tumour heterogeneity.

PROCEDURE

The robustness and reliability of LQB CNA analyses was evaluated. We performed retrospective CNA profiling using shallow whole-genome sequencing (sWGS) on paired plasma circulating cell-free DNA (cfDNA) and tissue DNA samples from routinely collected samples from paediatric patients (n = 128) representing different tumour entities, including osteosarcoma, Ewing sarcoma, rhabdomyosarcoma, Wilms tumour, brain tumours and neuroblastoma.

RESULTS

Overall, we observed a good concordance between CNAs in tissue DNA and cfDNA. The main cause of CNA discordance was found to be low cfDNA sample quality (i.e. the ratio of cfDNA (<700 bp) and high molecular weight DNA (>700 bp)). Furthermore, CNAs were observed that were present in cfDNA and not in tissue DNA, or vice-versa. In neuroblastoma samples, no false-positives or false-negatives were identified for the detection of the prognostic marker MYCN amplification.

CONCLUSION

In future prospective studies, CNA analysis on LQBs that are of sufficient quality can serve as a complementary assay for CNA analysis on tissue biopsies, as either cfDNA or tissue DNA can contain CNAs that cannot be identified in the other biomaterial.

New Advances in Liquid Biopsy Technologies for Anaplastic Lymphoma Kinase (ALK)-Positive Cancer

Cancer cells are characterized by high genetic instability, that favors tumor relapse. The identification of the genetic causes of relapse can direct next-line therapeutic choices. As tumor tissue rebiopsy at disease progression is not always feasible, noninvasive alternative methods are being explored. Liquid biopsy is emerging as a non-invasive, easy and repeatable tool to identify specific molecular alterations and monitor disease response during treatment. The dynamic follow-up provided by this analysis can provide useful predictive information and allow prompt therapeutic actions, tailored to the genetic profile of the recurring disease, several months before radiographic relapse. Oncogenic fusion genes are particularly suited for this type of analysis. Anaplastic Lymphoma Kinase (ALK) is the dominant driver oncogene in several tumors, including Anaplastic Large-Cell Lymphoma (ALCL), Non-Small Cell Lung Cancer (NSCLC) and others. Here we review recent findings in liquid biopsy technologies, including ctDNA, CTCs, exosomes, and other markers that can be investigated from plasma samples, in ALK-positive cancers.

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.

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.

Diagnostic accuracy of circulating-free DNA for the determination of MYCN amplification status in advanced-stage neuroblastoma: a systematic review and meta-analysis

Background

MYCN amplification (MNA) is the strongest indicator of poor prognosis in neuroblastoma (NB). This meta-analysis aims to determine the diagnostic accuracy of MNA analysis in circulating-free DNA (cfDNA) from advanced-stage NB patients.

Methods

A systematic review of electronic databases was conducted to identify studies exploring the detection of MNA in plasma/serum cfDNA from NB patients at diagnosis using PCR methodology. Pooled estimates for sensitivity, specificity and diagnostic odds ratio (DOR) were calculated by conducting a bivariate/HSROC random-effects meta-analysis.

Results

Seven studies, with a total of 529 advanced-stage patients, were eligible. The pooled sensitivity of cfDNA-based MNA analysis was 0.908 (95% CI, 0.818–0.956), the pooled specificity was 0.976 (0.940–0.991) and the DOR was 410.0 (−103.6 to 923.7). Sub-grouped by INSS stage, the sensitivity for stage 3 and 4 patients was 0.832 (0.677–0.921) and 0.930 (0.834–0.972), respectively. The specificity was 0.999 (0.109–1.000) and 0.974 (0.937–0.990), respectively, and the DOR was 7855.2 (−66267.0 to 81977.4) and 508.7 (−85.8 to 1103.2), respectively.

Conclusions

MNA analysis in cfDNA using PCR methodology represents a non-invasive approach to rapidly and accurately determine MNA status in patients with advanced-stage NB. Standardised methodology must be developed before this diagnostic test can enter the clinic.