ALK germline mutations in patients with neuroblastoma: a rare and weakly penetrant syndrome

Identification of ALK Mutation in Neuroblastoma on the Point of Molecular Heterogeneity

BACKGROUND AND AIM

In neuroblastoma, anaplastic lymphoma kinase mutations have recently received attention as molecular targets for the treatment of neuroblastoma, as 6% to 10% of patients with neuroblastoma have anaplastic lymphoma kinase mutations. There are little data from the cases in Turkey. We aimed to detect anaplastic lymphoma kinase mutations and molecular heterogeneity in neuroblastoma using next-generation sequencing. This study is the first one with this many cases in Turkey.

METHODS

Next-generation sequencing analysis was performed using an Illumina MiniSeq custom gene panel. Clinically important mutations were selected for the analysis. We also gathered clinical data of the patients from Turkish Pediatric Oncology Group cohorts to associate them with anaplastic lymphoma kinase mutations. This study is a retrospective cross-sectional study. We followed STROBE guideline (https://www.equator-network.org/reporting-guidelines/strobe/) on this study.

RESULTS

We analyzed anaplastic lymphoma kinase in 108 patients with neuroblastoma, with a mean age of 43.76 months. Pathogenic anaplastic lymphoma kinase mutations were detected in 13 patients (12.04%). We noted that anaplastic lymphoma kinase mutations were primarily observed in intermediate- and high-risk patients (P  =  .028). R1275Q and F1174-related mutations were predominant; I1171T, L1226F, S1189F, V1135A, and G1125S mutations were rare. Duplicate samples did not exhibit any heterogeneity.

CONCLUSIONS

We found that F1174 and R1275Q-related anaplastic lymphoma kinase mutations are the most common pathogenic mutations in neuroblastoma. Anaplastic lymphoma kinase mutation status did not show any heterogeneity, and the mutations were correlated with intermediate- or high-risk groups.

Multifocal Neuroblastoma and Central Hypoventilation in An Infant with Germline ALK F1174I Mutation

A preterm infant with central hypoventilation was diagnosed with multifocal neuroblastoma. Congenital anomalies of the autonomic nervous system in association with neuroblastoma are commonly associated with germline mutations in PHOX2B. Further, the ALK gene is frequently mutated in both familial and sporadic neuroblastoma. Sanger sequencing of ALK and PHOX2B, SNP microarray of three tumor samples and whole genome sequencing of tumor and blood were performed. Genetic testing revealed a germline ALK F1174I mutation that was present in all tumor samples as well as in normal tissue samples from the patient. Neither of the patient’s parents presented the ALK variant. Array profiling of the three tumor samples showed that two of them had only numerical aberrations, whereas one sample displayed segmental alterations, including a gain at chromosome 2p, resulting in two copies of the ALK-mutated allele. Whole genome sequencing confirmed the presence of the ALK variant and did not detect any aberrations in the coding or promotor region of PHOX2B. This study is to our knowledge the first to report a de novoALK F1174I germline mutation. This may not only predispose to congenital multifocal neuroblastoma but may also contribute to the respiratory dysfunction seen in this patient.

Durable Clinical Response to ALK Tyrosine Kinase Inhibitors in Epithelioid Inflammatory Myofibroblastic Sarcoma Harboring PRRC2B-ALK Rearrangement: A Case Report

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal neoplasm and patients with IMT tend to have a favorable outcome after complete surgical resection. However, some tumors of IMT cases have recurred and grown rapidly after successful surgery. Epithelioid inflammatory myofibroblastic sarcoma (EIMS) is a highly aggressive intra-abdominal IMT variant with epithelioid-to-round cell morphology. Currently, no standard therapy exists for recurrent or invasive IMTs and EIMS, but anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) are recommended for those harboring ALK gene rearrangements. We herein report the first case of PRRC2B-ALK fusion associated IMTs with clinical and pathological manifestation matched the diagnosis criteria of EIMS and the durable clinical response of the sequential use of ALK TKIs (crizotinib, alectinib, ceritinib, and lorlatinib). A female patient with EIMS of the greater omentum was suffering from a rapid recurrence after cytoreductive surgery was done. Crizotinib was administered when PRRC2B-ALK fusion was detected, and partial response was achieved. The progression-free survival (PFS) of crizotinib was 5 months. Alectinib was administered based on the results of second next-generation sequencing (NGS) analysis, which identified the secondary mutation ALK R1192P. The best overall response of alectinib treatment was a partial response (PR) and the PFS was 5.5 months. Ceritinib was prescribed as third-line therapy after alectinib resistance with ALK L1196M mutation. PR was achieved and the PFS of ceritinib was 6 months. The patient was taking lorlatinib after ceritinib resistance and achieved a stable disease at 2 months with the PFS more than 5 months. The overall survival was more than two years as of the time of manuscript preparation. We describe an EIMS of greater omentum caused by PRRC2B-ALK fusion gene and showed durable clinical response to the sequential use of ALK TKIs.

Sustained response to brigatinib in a patient with refractory metastatic pheochromocytoma harboring R1192P anaplastic lymphoma kinase mutation: a case report from the Austrian Group Medical Tumor Therapy next-generation sequencing registry and discussion of the literature

Metastatic pheochromocytoma and paraganglioma (PPGL) are rare diseases with dismal prognosis and standard therapies are lacking. We herein report the first case of a germline anaplastic lymphoma kinase (ALK) mutation in a patient with chemorefractory metastatic pheochromocytoma in the absence of mutations of known PPGL-associated predisposing genes. Therapy with the ALK inhibitor (ALKi) brigatinib led to dramatic and durable disease remission, despite previous disease progression on the ALKi alectinib. This case underscores the potential clinical use of molecular profiling in rare diseases with limited treatment options and suggests that the ALK-R1192P point mutation might predict sensitivity to brigatinib.

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First case of a germline ALK mutation in a patient with metastatic pheochromocytoma.

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Durable response to the ALKi brigatinib after disease progression on combination chemotherapy and alectinib.

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A germline ALK mutation in a patient with pheochromocytoma in the absence of mutations of known PPGL-associated genes.

Molecular Genetics in Neuroblastoma Prognosis

In recent years, much research has been carried out to identify the biological and genetic characteristics of the neuroblastoma (NB) tumor in order to precisely define the prognostic subgroups for improving treatment stratification. This review will describe the major genetic features and the recent scientific advances, focusing on their impact on diagnosis, prognosis, and therapeutic solutions in NB clinical management.

Predisposition to cancer in children and adolescents

Childhood malignancies are rarely related to known environmental exposures, and it has become increasingly evident that inherited genetic factors play a substantial causal role. Large-scale sequencing studies have shown that approximately 10% of children with cancer have an underlying cancer predisposition syndrome. The number of recognised cancer predisposition syndromes and cancer predisposition genes are constantly growing. Imaging and laboratory technologies are improving, and knowledge of the range of tumours and risk of malignancy associated with cancer predisposition syndromes is increasing over time. Consequently, surveillance measures need to be constantly adjusted to address these new findings. Management recommendations for individuals with pathogenic germline variants in cancer predisposition genes need to be established through international collaborative studies, addressing issues such as genetic counselling, cancer prevention, cancer surveillance, cancer therapy, psychological support, and social-ethical issues. This Review represents the work by a group of experts from the European Society for Paediatric Oncology (SIOPE) and aims to summarise the current knowledge and define future research needs in this evolving field.

The feasibility of adrenal-sparing surgery in bilateral adrenal neuroblastoma

PURPOSE

Loss of adrenal function is a major concern in the treatment of children with bilateral adrenal neuroblastoma (BAN). We aimed to evaluate the feasibility of adrenal-sparing surgery in this unique subgroup.

METHOD

Retrospective review of our center's neuroblastoma database was conducted. Patients with synchronous BAN confirmed at surgery were included. Their demographic data and clinical charts were analyzed.

RESULTS

Five patients were confirmed with BAN. Mean age at diagnosis was 0.89 (0.39-1.32) years; male:female ratio was 4:1. They were stratified as stages M (n = 2), MS (n = 1), L1 (n = 1) and L2 (n = 1). MYCN amplification was present in 1 patient (stage M) and was stratified as high-risk group. All patients except one received preoperative chemotherapy. Among the 10 adrenal gland tumors, 2 underwent tumor adrenalectomy (TA) and 8 had adrenal-sparing tumorectomy (AST). After chemotherapy, 3 patients underwent single-stage bilateral AST and 1 patient underwent 2-stage TA-AST. One patient underwent upfront single-stage TA-AST, where lack of preoperative chemotherapy rendered the adrenal gland indistinguishable. The high-risk patient received autologous hematopoietic cell transplantation for consolidation. No patients required adrenal replacement therapy. All patients were alive without evidence of disease with mean follow-up 5.5 (2.6-8.5) years.

CONCLUSION

Adrenal-sparing surgery is feasible in patients with BAN.

LEVEL OF EVIDENCE

Level IV (case series with no comparison group).

Targeting anaplastic lymphoma kinase in neuroblastoma

Over the last decade, anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase (RTK), has been identified as a fusion partner in a diverse variety of translocation events resulting in oncogenic signaling in many different cancer types. In tumors where the full‐length ALK RTK itself is mutated, such as neuroblastoma, the picture regarding the role of ALK as an oncogenic driver is less clear. Neuroblastoma is a complex and heterogeneous tumor that arises from the neural crest derived peripheral nervous system. Although high‐risk neuroblastoma is rare, it often relapses and becomes refractory to treatment. Thus, neuroblastoma accounts for 10–15% of all childhood cancer deaths. Since most cases are in children under the age of 2, understanding the role and regulation of ALK during neural crest development is an important goal in addressing neuroblastoma tumorigenesis. An impressive array of tyrosine kinase inhibitors (TKIs) that act to inhibit ALK have been FDA approved for use in ALK‐driven cancers. ALK TKIs bind differently within the ATP‐binding pocket of the ALK kinase domain and have been associated with different resistance mutations within ALK itself that arise in response to therapeutic use, particularly in ALK‐fusion positive non‐small cell lung cancer (NSCLC). This patient population has highlighted the importance of considering the relevant ALK TKI to be used for a given ALK mutant variant. In this review, we discuss ALK in neuroblastoma, as well as the use of ALK TKIs and other strategies to inhibit tumor growth. Current efforts combining novel approaches and increasing our understanding of the oncogenic role of ALK in neuroblastoma are aimed at improving the efficacy of ALK TKIs as precision medicine options in the clinic.

Duplication of ALK F1245 missense mutation due to acquired uniparental disomy associated with aggressive progression in a patient with relapsed neuroblastoma

Recent genome-wide analysis of neuroblastoma (NBL) revealed amplification and heterozygous mutation of anaplastic lymphoma kinase (ALK) are responsible for oncogenicity, frequently observed during relapses. A 3-year-old girl with relapsed high-risk NBL had a heterozygous ALK F1245L mutation at diagnosis, which became homozygous due to uniparental disomy (UPD) of the entire chromosome 2, confirmed by single nucleotide polymorphism array and variant allele frequency of this mutation. The ALK inhibitor, crizotinib, failed to control the tumor and the patient died of the disease. Further genomic analysis using targeted capture sequencing for 381 genes related to pediatric cancers identified more alterations acquired at relapse, such as TSC complex subunit 2 and protein tyrosine phosphatase receptor type D. In addition to these several acquired mutations, this extremely rare duplication of ALK mutation might explain the aggressive clinical course after relapse, because acquired UPD, resulting in the duplication of an oncogenic mutation, has been reported for various neoplasms. Although a clinical benefit of ALK inhibitors in patients with NBL has not been confirmed yet, a treatment based on the ALK mutation status will be promising in future using more potent next-generation ALK inhibitors.

Retrospective evaluation of a decision-support algorithm (MIPOGG) for genetic referrals for children with neuroblastic tumors

BACKGROUND

Neuroblastoma is the most common pediatric extracranial solid tumor. Germline pathogenic variants in ALK and PHOX2B, as well as other cancer predisposition genes, are increasingly implicated in the pathogenesis of neuroblastic tumors. A challenge for clinicians is the identification of children with neuroblastoma who require genetics evaluation for underlying cancer predisposition syndromes (CPS).

PROCEDURE

We developed a decisional algorithm (MIPOGG) to identify which patients with neuroblastic tumors have an increased likelihood of an underlying CPS. This algorithm, comprising 11 Yes/No questions, evaluates features in the tumor, personal and family history that are suggestive of an underlying CPS. We assessed the algorithm's performance in a retrospective cohort.

RESULTS

Two hundred and nine of 278 consecutive patients with neuroblastic tumors at The Hospital for Sick Children (2007-2016) had sufficient clinical data for retrospective application of the decisional algorithm. Fifty-one of 209 patients had been referred to genetics for CPS evaluation; 6/51 had a genetic or clinical confirmation of a CPS. The algorithm correctly identified all six children (Beckwith-Wiedemann (n = 2), Fanconi anemia, RB1, PHOX2B, chromosome duplication involving ALK) as requiring a genetic evaluation by using clinical features present at diagnosis. The level of agreement between the algorithm and physicians was 83.9%, with 15 more patients identified by the algorithm than by physicians as requiring a genetics referral.

CONCLUSIONS

This decisional algorithm appropriately detected all patients who, following genetic evaluation, were confirmed to have a CPS and may improve the detection of CPS in patients with neuroblastic tumors compared with current practice.

Two siblings with familial neuroblastoma with distinct clinical phenotypes harboring an ALK germline mutation

The authors report two siblings with familial neuroblastoma with a germline R1275Q mutation of the tyrosine kinase domain of ALK. Whole exome sequencing and copy number variation assay were performed to investigate genetic alterations in the two cases. No common somatic mutations or gene polymorphisms related to the tumorigenesis of neuroblastoma were detected. A distinct pattern involving both segmental chromosomal alteration and MYCN amplification was detected. The diversity of biological behavior of familial neuroblastoma harboring a germline ALK mutation may depend on conventional prognostic factors, such as segmental chromosomal alterations and MYCN amplification, rather than additional acquired mutations.

Genetic susceptibility to neuroblastoma: current knowledge and future directions

Neuroblastoma, a malignancy of the developing peripheral nervous system that affects infants and young children, is a complex genetic disease. Over the past two decades, significant progress has been made toward understanding the genetic determinants that predispose to this often lethal childhood cancer. Approximately 1-2% of neuroblastomas are inherited in an autosomal dominant fashion and a combination of co-morbidity and linkage studies has led to the identification of germline mutations in PHOX2B and ALK as the major genetic contributors to this familial neuroblastoma subset. The genetic basis of "sporadic" neuroblastoma is being studied through a large genome-wide association study (GWAS). These efforts have led to the discovery of many common susceptibility alleles, each with modest effect size, associated with the development and progression of sporadic neuroblastoma. More recently, next-generation sequencing efforts have expanded the list of potential neuroblastoma-predisposing mutations to include rare germline variants with a predicted larger effect size. The evolving characterization of neuroblastoma's genetic basis has led to a deeper understanding of the molecular events driving tumorigenesis, more precise risk stratification and prognostics and novel therapeutic strategies. This review details the contemporary understanding of neuroblastoma's genetic predisposition, including recent advances and discusses ongoing efforts to address gaps in our knowledge regarding this malignancy's complex genetic underpinnings.

TKI sensitivity patterns of novel kinase-domain mutations suggest therapeutic opportunities for patients with resistant ALK+ tumors

The anaplastic lymphoma kinase (ALK) protein drives tumorigenesis in subsets of several tumors through chromosomal rearrangements that express and activate its C-terminal kinase domain. In addition, germline predisposition alleles and acquired mutations are found in the full-length protein in the pediatric tumor neuroblastoma. ALK-specific tyrosine kinase inhibitors (TKIs) have become important new drugs for ALK-driven lung cancer, but acquired resistance via multiple mechanisms including kinase-domain mutations eventually develops, limiting median progression-free survival to less than a year. Here we assess the impact of several kinase-domain mutations that arose during TKI resistance selections of ALK+ anaplastic large-cell lymphoma (ALCL) cell lines. These include novel variants with respect to ALK-fusion cancers, R1192P and T1151M, and with respect to ALCL, F1174L and I1171S. We assess the effects of these mutations on the activity of six clinical inhibitors in independent systems engineered to depend on either the ALCL fusion kinase NPM-ALK or the lung-cancer fusion kinase EML4-ALK. Our results inform treatment strategies with a likelihood of bypassing mutations when detected in resistant patient samples and highlight differences between the effects of particular mutations on the two ALK fusions.

Maternal Immunization: New Perspectives on Its Application Against Non-Infectious Related Diseases in Newborns

The continuous evolution in preventive medicine has anointed vaccination a versatile, human-health improving tool, which has led to a steady decline in deaths in the developing world. Maternal immunization represents an incisive step forward for the field of vaccination as it provides protection against various life-threatening diseases in pregnant women and their children. A number of studies to improve prevention rates and expand protection against the largest possible number of infections are still in progress. The complex unicity of the mother-infant interaction, both during and after pregnancy and which involves immune system cells and molecules, is an able partner in the success of maternal immunization, as intended thus far. Interestingly, new studies have shed light on the versatility of maternal immunization in protecting infants from non-infectious related diseases, such as allergy, asthma and congenital metabolic disorders. However, barely any attempt at applying maternal immunization to the prevention of childhood cancer has been made. The most promising study reported in this new field is a recent proof of concept on the efficacy of maternal immunization in protecting cancer-prone offspring against mammary tumor progression. New investigations into the possibility of exploiting maternal immunization to prevent the onset and/or progression of neuroblastoma, one of the most common childhood malignancies, are therefore justified. Maternal immunization is presented in a new guise in this review. Attention will be focused on its versatility and potential applications in preventing tumor progression in neuroblastoma-prone offspring.

Retinoblastoma and Neuroblastoma Predisposition and Surveillance

Retinoblastoma (RB) is the most common intraocular malignancy in childhood. Approximately 40% of retinoblastomas are hereditary and due to germline mutations in the RB1 gene. Children with hereditary RB are also at risk for developing a midline intracranial tumor, most commonly pineoblastoma. We recommend intensive ocular screening for patients with germline RB1 mutations for retinoblastoma as well as neuroimaging for pineoblastoma surveillance. There is an approximately 20% risk of developing second primary cancers among individuals with hereditary RB, higher among those who received radiotherapy for their primary RB tumors. However, there is not yet a clear consensus on what, if any, screening protocol would be most appropriate and effective. Neuroblastoma (NB), an embryonal tumor of the sympathetic nervous system, accounts for 15% of pediatric cancer deaths. Prior studies suggest that about 2% of patients with NB have an underlying genetic predisposition that may have contributed to the development of NB. Germline mutations in ALK and PHOX2B account for most familial NB cases. However, other cancer predisposition syndromes, such as Li-Fraumeni syndrome, RASopathies, and others, may be associated with an increased risk for NB. No established protocols for NB surveillance currently exist. Here, we describe consensus recommendations on hereditary RB and NB from the AACR Childhood Cancer Predisposition Workshop. Clin Cancer Res; 23(13); e98-e106. ©2017 AACRSee all articles in the online-only CCR Pediatric Oncology Series.

Neuroblastoma in children: Update on clinicopathologic and genetic prognostic factors

Neuroblastoma is the most common extracranial solid tumor in childhood accounting for 8-10% of all childhood malignancies. The tumor is characterized by a spectrum of histopathologic features and a heterogeneous clinical phenotype. Modern multimodality therapy results in variable clinical response ranging from cure in localized tumors to limited response in aggressive metastatic disease. Accurate clinical staging and risk assessment based on clinical, surgical, biologic and pathologic criteria are of pivotal importance in assigning prognosis and planning effective treatment approaches. Numerous studies have analyzed the presence of several clinicopathologic and biologic factors in association with the patient's prognosis and outcome. Although patient's age, tumor stage, histopathologic classification, and MYCN amplification are the most commonly validated prognostic markers, several new gene mutations have been identified in sporadic and familial neuroblastoma cases that show association with an adverse outcome. Novel molecular studies have also added data on chromosomal segmental aberrations in MYCN nonamplified tumors. In this review, we provide an updated summary of the clinical, serologic and genetic prognostic indicators in neuroblastoma including classic factors that have consistently played a role in risk stratification of patients as well as newly discovered biomarkers that may show a potential significance in patients' management.

A Comprehensive Review of Pediatric Tumors and Associated Cancer Predisposition Syndromes

An understanding of the role of inherited cancer predisposition syndromes in pediatric tumor diagnoses continues to develop as more information is learned through the application of genomic technology. Identifying patients and their relatives at an increased risk for developing cancer is an important step in the care of this patient population. The purpose of this review is to highlight various tumor types that arise in the pediatric population and the cancer predisposition syndromes associated with those tumors. The review serves as a guide for recognizing genes and conditions to consider when a pediatric cancer referral presents to the genetics clinic.

Comparison of Clinical Features and Outcomes in Patients With Bilateral Versus Unilateral Adrenal Neuroblastoma

BACKGROUND

While nearly half of cases of neuroblastoma arise in one of the adrenal glands, bilateral origin is rare. We aimed to compare clinical characteristics and outcomes between patients with bilateral versus unilateral adrenal neuroblastoma.

PROCEDURE

We utilized the Surveillance, Epidemiology, and End Results database to identify patients with bilateral and unilateral adrenal neuroblastoma from 1973 to 2012. We used Fisher exact tests to compare demographics and clinical features between groups. We used Kaplan-Meier methods to describe the 5-year overall survival rate for these 2 groups. We conducted a literature review to complement the Surveillance, Epidemiology, and End Results data.

RESULTS

Of 1617 patients in the cohort, 1585 (98%) had unilateral disease and 32 (2%) had bilateral disease. Compared with patients with unilateral disease, a significantly greater proportion of patients with bilateral disease was below 1 year of age (53.1% vs. 31.8%; P=0.01) and had distant metastasis at diagnosis (90.6% vs. 69.0%; P=0.006). The 5-year overall survival rate for patients diagnosed with bilateral disease was 70.5% (95% confidence interval, 45.1%-85.8%), compared with 62.4% (95% confidence interval, 59.7%-65%) for patients with unilateral disease (P=0.26).

CONCLUSIONS

Compared with patients with unilateral disease, patients with bilateral adrenal neuroblastoma are younger, more likely to have distant metastasis, and have a favorable outcome.

Next-generation sequencing reveals germline mutations in an infant with synchronous occurrence of nephro- and neuroblastoma

Although neuro- and nephroblastoma are common solid tumors in children, the simultaneous occurrence is very rare and is often associated with syndromes. Here, we present a unique case of synchronous occurrence of neuro- and nephroblastoma in an infant with no signs of congenital anomalies or a syndrome. We performed genetic testing for possible candidate genes as underlying mutation using the next-generation sequencing (NGS) approach to target 94 genes and 284 single-nucleotide polymorphisms (SNPs) involved in cancer. We uncovered a novel heterozygous germline missense mutation p.F58L (c.172T→C) in the anaplastic lymphoma kinase (ALK) gene and one novel heterozygous rearrangement Q418Hfs(*)11 (c.1254_1264delins TTACTTAGTACAAGAACTG) in the Fanconi anemia gene FANCD2 leading to a truncated protein. Besides, several SNPs associated with the occurrence of neuroblastoma and/or nephroblastoma or multiple primary tumors were identified. The next-generation sequencing approach might in the future be useful not only in understanding tumor etiology but also in recognizing new genetic markers and targets for future personalized therapy.

Genetics of Bladder Malignant Tumors in Childhood

Bladder masses are represented by either benign or malignant entities. Malignant bladder tumors are frequent causes of disease and death in western countries. However, in children they are less common. Additionally, different features are found in childhood, in which non epithelial tumors are more common than epithelial ones. Rhabdomyosarcoma is the most common pediatric bladder tumor, but many other types of lesions may be found, such as malignant rhabdoid tumor (MRT), inflammatory myofibroblastic tumor and neuroblastoma. Other rarer tumors described in literature include urothelial carcinoma and other epithelial neoplasms. Rhabdomyosarcoma is associated to a variety of genetic syndromes and many genes are involved in tumor development. PAX3-FKHR and PAX7-FKHR (P-F) fusion state has important implications in the pathogenesis and biology of RMS, and different genes alterations are involved in the pathogenesis of P-F negative and embryonal RMS, which are the subsets of tumors most frequently affecting the bladder. These genes include p53, MEF2, MYOG, Ptch1, Gli1, Gli3, Myf5, MyoD1, NF1, NRAS, KRAS, HRAS, FGFR4, PIK3CA, CTNNB1, FBXW7, IGF1R, PDGFRA, ERBB2/4, MET, BCOR. Malignant rhabdoid tumor (MRT) usually shows SMARCB1/INI1 alterations. Anaplastic lymphoma kinase (ALK) gene translocations are the most frequently associated alterations in inflammatory myofibroblastic tumor (IMT). Few genes alterations in urothelial neoplasms have been reported in the paediatric population, which are mainly related to deletion of p16/lnk4, overexpression of CK20 and overexpression of p53. Here, we reviewed available literature to identify genes associated to bladder malignancies in children and discussed their possible relationships with these tumors.

Oncologic Phenotype of Peripheral Neuroblastic Tumors Associated With PHOX2B Non-Polyalanine Repeat Expansion Mutations

BACKGROUND

Germline non-polyalanine repeat expansion mutations in PHOX2B (PHOX2B NPARM) predispose to peripheral neuroblastic tumors (PNT), frequently in association with other neurocristopathies: Hirschsprung disease (HSCR) or congenital central hypoventilation syndrome (CCHS). Although PHOX2B polyalanine repeat expansions predispose to a low incidence of benign PNTs, the oncologic phenotype associated with PHOX2B NPARM is still not known in detail.

METHODS

We analyzed prognostic factors, treatment toxicity, and outcome of patients with PNT and PHOX2B NPARM.

RESULTS

Thirteen patients were identified, six of whom also had CCHS and/or HSCR, one also had late-onset hypoventilation with hypothalamic dysfunction (LO-CHS/HD), and six had no other neurocristopathy. Four tumours were "poorly differentiated," and nine were differentiated, including five ganglioneuromas, three ganglioneuroblastomas, and one differentiating neuroblastoma, hence illustrating that PHOX2B NPARM are predominantly associated with differentiating tumors. Nevertheless, three patients had stage 4 and one patient had stage 3 disease. Segmental chromosomal alterations, correlating with poor prognosis, were found in all the six tumors analyzed by array-comparative genomic hybridization. One patient died of tumor progression, one is on palliative care, one died of hypoventilation, and 10 patients are still alive, with median follow-up of 5 years.

CONCLUSIONS

Based on histological phenotype, our series suggests that heterozygous PHOX2B NPARM do not fully preclude ganglion cell differentiation in tumors. However, this tumor predisposition syndrome may also be associated with poorly differentiated tumors with unfavorable genomic profiles and clinically aggressive behaviors. The intrafamilial variability and the unpredictable tumor prognosis should be considered in genetic counseling.

Activated Alk triggers prolonged neurogenesis and Ret upregulation providing a therapeutic target in ALK-mutated neuroblastoma

Activating mutations of the ALK (Anaplastic lymphoma Kinase) gene have been identified in sporadic and familial cases of neuroblastoma, a cancer of early childhood arising from the sympathetic nervous system (SNS). To decipher ALK function in neuroblastoma predisposition and oncogenesis, we have characterized knock-in (KI) mice bearing the two most frequent mutations observed in neuroblastoma patients. A dramatic enlargement of sympathetic ganglia is observed in AlkF1178L mice from embryonic to adult stages associated with an increased proliferation of sympathetic neuroblasts from E14.5 to birth. In a MYCN transgenic context, the F1178L mutation displays a higher oncogenic potential than the R1279Q mutation as evident from a shorter latency of tumor onset. We show that tumors expressing the R1279Q mutation are sensitive to ALK inhibition upon crizotinib treatment. Furthermore, our data provide evidence that activated ALK triggers RET upregulation in mouse sympathetic ganglia at birth as well as in murine and human neuroblastoma. Using vandetanib, we show that RET inhibition strongly impairs tumor growth in vivo in both MYCN/KI AlkR1279Q and MYCN/KI AlkF1178L mice. Altogether, our findings demonstrate the critical role of activated ALK in SNS development and pathogenesis and identify RET as a therapeutic target in ALK mutated neuroblastoma.

ALK mutations confer differential oncogenic activation and sensitivity to ALK inhibition therapy in neuroblastoma

Genetic studies have established anaplastic lymphoma kinase (ALK), a cell surface receptor tyrosine kinase, as a tractable molecular target in neuroblastoma. We describe comprehensive genomic, biochemical, and computational analyses of ALK mutations across 1,596 diagnostic neuroblastoma samples. ALK tyrosine kinase domain mutations occurred in 8% of samples--at three hot spots and 13 minor sites--and correlated significantly with poorer survival in high- and intermediate-risk neuroblastoma. Biochemical and computational studies distinguished oncogenic (constitutively activating) from nononcogenic mutations and allowed robust computational prediction of their effects. The mutated variants also showed differential in vitro crizotinib sensitivities. Our studies identify ALK genomic status as a clinically important therapeutic stratification tool in neuroblastoma and will allow tailoring of ALK-targeted therapy to specific mutations.

Recent insights into the biology of neuroblastoma

Neuroblastoma (NB) is an embryonal tumor of the sympathetic nervous system which accounts for 8-10% of pediatric cancers. It is characterized by a broad spectrum of clinical behaviors from spontaneous regression to fatal outcome despite aggressive therapies. Considerable progress has been made recently in the germline and somatic genetic characterization of patients and tumors. Indeed, predisposition genes that account for a significant proportion of familial and syndromic cases have been identified and genome-wide association studies have retrieved a number of susceptibility loci. In addition, genome-wide sequencing, copy-number and expression studies have been conducted on tumors and have detected important gene modifications, profiles and signatures that have strong implications for the therapeutic stratification of patients. The identification of major players in NB oncogenesis, including MYCN, ALK, PHOX2B and LIN28B, has enabled the development of new animal models. Our review focuses on these recent advances, on the insights they provide on the mechanisms involved in NB development and their applications for the clinical management of patients.

High-resolution array CGH profiling identifies Na/K transporting ATPase interacting 2 (NKAIN2) as a predisposing candidate gene in neuroblastoma

Neuroblastoma (NB), the most common solid cancer in early childhood, usually occurs sporadically but also its familial occurance is known in 1-2% of NB patients. Germline mutations in the ALK and PHOX2B genes have been found in a subset of familial NBs. However, because some individuals harbouring mutations in these genes do not develop this tumor, additional genetic alterations appear to be required for NB pathogenesis. Herein, we studied an Italian family with three NB patients, two siblings and a first cousin, carrying an ALK germline-activating mutation R1192P, that was inherited from their unaffected mothers and with no mutations in the PHOX2B gene. A comparison between somatic and germline DNA copy number changes in the two affected siblings by a high resolution array-based Comparative Genomic Hybridization (CGH) analysis revealed a germline gain at NKAIN2 (Na/K transporting ATPase interacting 2) locus in one of the sibling, that was inherited from the parent who does not carry the ALK mutation. Surprisingly, NKAIN2 was expressed at high levels also in the affected sibling that lacks the genomic gain at this locus, clearly suggesting the existance of other regulatory mechanisms. High levels of NKAIN2 were detected in the MYCN-amplified NB cell lines and in the most aggressive NB lesions as well as in the peripheral blood of a large cohort of NB patients. Consistent with a role of NKAIN2 in NB development, NKAIN2 was down-regulated during all-trans retinoic acid differentiation in two NB cell lines. Taken together, these data indicate a potential role of NKAIN2 gene in NB growth and differentiation.

Mechanistic insight into ALK receptor tyrosine kinase in human cancer biology

The burgeoning field of anaplastic lymphoma kinase (ALK) in cancer encompasses many cancer types, from very rare cancers to the more prevalent non-small-cell lung cancer (NSCLC). The common activation of ALK has led to the use of the ALK tyrosine kinase inhibitor (TKI) crizotinib in a range of patient populations and to the rapid development of second-generation drugs targeting ALK. In this Review, we discuss our current understanding of ALK function in human cancer and the implications for tumour treatment.

The role of genetic and epigenetic alterations in neuroblastoma disease pathogenesis

Neuroblastoma is a highly heterogeneous tumor accounting for 15 % of all pediatric cancer deaths. Clinical behavior ranges from the spontaneous regression of localized, asymptomatic tumors, as well as metastasized tumors in infants, to rapid progression and resistance to therapy. Genomic amplification of the MYCN oncogene has been used to predict outcome in neuroblastoma for over 30 years, however, recent methodological advances including miRNA and mRNA profiling, comparative genomic hybridization (array-CGH), and whole-genome sequencing have enabled the detailed analysis of the neuroblastoma genome, leading to the identification of new prognostic markers and better patient stratification. In this review, we will describe the main genetic factors responsible for these diverse clinical phenotypes in neuroblastoma, the chronology of their discovery, and the impact on patient prognosis.