Prognostic factors of CNS tumours in Neurofibromatosis 1 (NF1): a retrospective study of 104 patients

Low-grade glioma in children with neurofibromatosis type 1: surveillance, treatment indications, management, and future directions

Neurofibromatosis type 1 (NF1) is an autosomal dominant cancer predisposition syndrome characterized by the development of both central and peripheral nervous system tumors. Low-grade glioma (LGG) is the most prevalent central nervous system tumor occurring in children with NF1, arising most frequently within the optic pathway, followed by the brainstem. Historically, treatment of NF1-LGG has been limited to conventional cytotoxic chemotherapy and surgery. Despite treatment with chemotherapy, a subset of children with NF1-LGG fail initial therapy, have a continued decline in function, or recur. The recent development of several preclinical models has allowed for the identification of novel, molecularly targeted therapies. At present, exploration of these novel precision-based therapies is ongoing in the preclinical setting and through larger, collaborative clinical trials. Herein, we review the approach to surveillance and management of NF1-LGG in children and discuss upcoming novel therapies and treatment protocols.

Diagnosis and management of neurofibromatosis type 1 in Arabian Gulf Cooperation Council Region: challenges and recommendations

Neurofibromatosis type 1 (NF1) is a complex multisystem genetic disorder that requires long-term, age-specific monitoring and multidisciplinary care. NF1 symptom burden can significantly affect the quality of life and impose a substantial economic burden on patients and their families. The approval and widespread availability of mitogen-activated protein kinase (MEK) inhibitors such as selumetinib for NF1-related plexiform neurofibromas have revolutionized the standard of care for patients with NF1, however their effective utilization hinges on early recognition of NF1. We present a consensus manuscript describing the challenges observed in the Arabian Gulf Cooperation Council (GCC) for diagnosing and managing NF1. Experts from the GCC also present recommendations for the early recognition and management of NF1 and its complications. A referral pathway that can play a crucial role in helping primary healthcare providers refer their patients to experts is also proposed. Increasing the availability and accessibility of genetic testing at an affordable cost and optimizing personalized NF1 care are essential for NF1 management. Developing regional guidelines for NF1 management and establishing NF1 centers of excellence may facilitate better care and outcomes for patients with NF1 in the GCC region.

Multiparametric whole-body MRI of patients with neurofibromatosis type I: spectrum of imaging findings

Neurofibromatosis (NF) type I is a neuroectodermal and mesodermal dysplasia caused by a mutation of the neurofibromin tumor suppressor gene. Phenotypic features of NF1 vary, and patients develop benign peripheral nerve sheath tumors and malignant neoplasms, such as malignant peripheral nerve sheath tumor, malignant melanoma, and astrocytoma. Multiparametric whole-body MR imaging (WBMRI) plays a critical role in disease surveillance. Multiparametric MRI, typically used in prostate imaging, is a general term for a technique that includes multiple sequences, i.e. anatomic, diffusion, and Dixon-based pre- and post-contrast imaging. This article discusses the value of multiparametric WBMRI and illustrates the spectrum of whole-body lesions of NF1 in a single imaging setting. Examples of lesions include those in the skin (tumors and axillary freckling), soft tissues (benign and malignant peripheral nerve sheath tumors, visceral plexiform, and diffuse lesions), bone and joints (nutrient nerve lesions, non-ossifying fibromas, intra-articular neurofibroma, etc.), spine (acute-angled scoliosis, dural ectasia, intraspinal tumors, etc.), and brain/skull (optic nerve glioma, choroid plexus xanthogranuloma, sphenoid wing dysplasia, cerebral hamartomas, etc.). After reading this article, the reader will gain knowledge of the variety of lesions encountered with NF1 and their WBMRI appearances. Timely identification of such lesions can aid in accurate diagnosis and appropriate patient management.

NF1 mutation-driven neuronal hyperexcitability sets a threshold for tumorigenesis and therapeutic targeting of murine optic glioma

BACKGROUND

With the recognition that noncancerous cells function as critical regulators of brain tumor growth, we recently demonstrated that neurons drive low-grade glioma initiation and progression. Using mouse models of neurofibromatosis type 1 (NF1)-associated optic pathway glioma (OPG), we showed that Nf1 mutation induces neuronal hyperexcitability and midkine expression, which activates an immune axis to support tumor growth, such that high-dose lamotrigine treatment reduces Nf1-OPG proliferation. Herein, we execute a series of complementary experiments to address several key knowledge gaps relevant to future clinical translation.

METHODS

We leverage a collection of Nf1-mutant mice that spontaneously develop OPGs to alter both germline and retinal neuron-specific midkine expression. Nf1-mutant mice harboring several different NF1 patient-derived germline mutations were employed to evaluate neuronal excitability and midkine expression. Two distinct Nf1-OPG preclinical mouse models were used to assess lamotrigine effects on tumor progression and growth in vivo.

RESULTS

We establish that neuronal midkine is both necessary and sufficient for Nf1-OPG growth, demonstrating an obligate relationship between germline Nf1 mutation, neuronal excitability, midkine production, and Nf1-OPG proliferation. We show anti-epileptic drug (lamotrigine) specificity in suppressing neuronal midkine production. Relevant to clinical translation, lamotrigine prevents Nf1-OPG progression and suppresses the growth of existing tumors for months following drug cessation. Importantly, lamotrigine abrogates tumor growth in two Nf1-OPG strains using pediatric epilepsy clinical dosing.

CONCLUSIONS

Together, these findings establish midkine and neuronal hyperexcitability as targetable drivers of Nf1-OPG growth and support the use of lamotrigine as a potential chemoprevention or chemotherapy agent for children with NF1-OPG.

Identifying Lesions of the Corpus Callosum in Patients With Neurofibromatosis Type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a multisystemic autosomal dominant disorder that includes intracranial lesions such as unidentified bright objects (UBOs)-areas of increased T2 signal on magnetic resonance imaging (MRI)-and tumors known as gliomas. The presence of these lesions in the corpus callosum (CC) has not been previously studied in a large cohort.

METHODS

We reviewed medical records of 681 patients (aged three months to 86 years) followed at our institution from 2000 to 2023 with NF1 and one or more brain MRI. Patients with lesions in the CC were identified, and RAPNO/RANO criteria were used to determine changes in size over time, where a change of 25% in the product of perpendicular measurements indicates growth or shrinkage.

RESULTS

Forty-seven patients had CC UBOs, most of which were in the splenium (66.0%). Seventeen patients had CC gliomas (10% of those with any glioma), two of whom had two gliomas. Seventeen of 19 gliomas were in the splenium. Over follow-up, eight of 19 remained stable, three shrunk, and eight grew. The mean percentage change in the product of the dimensions was 311.5% (ranging from -46.7% to 2566.6%). Of the eight lesions that grew, one required treatment.

CONCLUSIONS

There is a 6.9% and 2.5% prevalence of CC UBOs and gliomas, respectively, in our cohort of patients with NF1. Most lesions are present in the splenium, and although some gliomas demonstrate significant growth, they rarely require treatment. This work is the largest series of CC lesions in NF1 and adds to the growing data to inform appropriate follow-up.

Magnetic Resonance Imaging of Central Nervous System Manifestations of Type 1 Neurofibromatosis: Pictorial Review and Retrospective Study of Their Frequency in a Cohort of Patients

Background: type 1 neurofibromatosis (NF1) is the most common neurocutaneous disorder, and it is an inherited condition that causes a tumour predisposition. Central nervous system (CNS) manifestations are a significant cause of morbidity and mortality in NF1. We provide a pictorial review of neuroradiological features of NF1, with emphasis on magnetic resonance imaging (MRI), and we assess the frequency of those features on a cohort of NF1 patients. Methods: we retrospectively evaluated all patients with a diagnosis of NF1 who underwent MRI of the spine and brain in our centre over a period of almost 5 years. A total of 74 patients were enrolled, 28 males and 46 females, with a mean age of 21 ± 12.67 years. The frequency of CNS manifestations encountered in our cohort of NF1 patients was assessed and compared with the data found in other studies published in the literature. Results: many of our findings were in line with the literature, and possible interpretations for those that turned out to be different were suggested in the discussion. Conclusion: imaging plays a central role in the diagnosis and management of NF1, and the knowledge of CNS manifestations could be critical for its early detection and identification, such as for treatment planning and prognostic implications.

An Overview of Optic Pathway Glioma With Neurofibromatosis Type 1: Pathogenesis, Risk Factors, and Therapeutic Strategies

Optic pathway gliomas (OPGs) are most predominant pilocytic astrocytomas, which are typically diagnosed within the first decade of life. The majority of affected children with OPGs also present with neurofibromatosis type 1 (NF1), the most common tumor predisposition syndrome. OPGs in individuals with NF1 primarily affect the optic pathway and lead to visual disturbance. However, it is challenging to assess risk in asymptomatic patients without valid biomarkers. On the other hand, for symptomatic patients, there is still no effective treatment to prevent or recover vision loss. Therefore, this review summarizes current knowledge regarding the pathogenesis of NF1-associated OPGs (NF1-OPGs) from preclinical studies to seek potential prognostic markers and therapeutic targets. First, the loss of the NF1 gene activates 3 distinct Ras effector pathways, including the PI3K/AKT/mTOR pathway, the MEK/ERK pathway, and the cAMP pathway, which mediate glioma tumorigenesis. Meanwhile, non-neoplastic cells from the tumor microenvironment (microglia, T cells, neurons, etc.) also contribute to gliomagenesis via various soluble factors. Subsequently, we investigated potential genetic risk factors, molecularly targeted therapies, and neuroprotective strategies for tumor prevention and vision recovery. Last, potential directions and promising preclinical models of NF1-OPGs are presented for further research. On the whole, NF1-OPGs develop as a result of the interaction between glioma cells and the tumor microenvironment. Developing effective treatments require a better understanding of tumor molecular characteristics, as well as multistage interventions targeting both neoplastic cells and non-neoplastic cells.

The management of neurofibromatosis type 1 (NF1) in children and adolescents

INTRODUCTION

Neurofibromatosis type 1 (NF1) is a rare neurogenetic disorder characterized by multiple organ system involvement and a predisposition to benign and malignant tumor development. With revised NF1 clinical criteria and the availability of germline genetic testing, there is now an opportunity to render an early diagnosis, expedite medical surveillance, and initiate treatment in a prompt and targeted manner.

AREAS COVERED

The authors review the spectrum of medical problems associated with NF1, focusing specifically on children and young adults. The age-dependent appearance of NF1-associated features is highlighted, and the currently accepted medical treatments are discussed. Additionally, future directions for optimizing the care of this unique population of children are outlined.

EXPERT OPINION

The appearance of NF1-related medical problems is age dependent, requiring surveillance for those features most likely to occur at any given age during childhood. As such, we advocate a life stage-focused screening approach beginning in infancy and continuing through the transition to adult care. With early detection, it becomes possible to promptly institute therapies and reduce patient morbidity. Importantly, with continued advancement in our understanding of disease pathogenesis, future improvements in the care of children with NF1 might incorporate improved risk assessments and more personalized molecularly targeted treatments.

Cancer Predisposition Syndromes in Neuro-oncology

Although most primary central and peripheral nervous system (NS) tumors occur sporadically, there are a subset that may arise in the context of a cancer predisposition syndrome. These syndromes occur due to a pathogenic mutation in a gene that normally functions as a tumor suppressor. With increased understanding of the molecular pathogenesis of these tumors, more people have been identified with a cancer predisposition syndrome. Identification is crucial, as this informs surveillance, diagnosis, and treatment options. Moreover, relatives can also be identified through genetic testing. Although there are many cancer predisposition syndromes that increase the risk of NS tumors, in this review, we focus on three of the most common cancer predisposition syndromes, neurofibromatosis type 1, neurofibromatosis type 2, and tuberous sclerosis complex type 1 and type 2, emphasizing the clinical manifestations, surveillance guidelines, and treatment options.

Pediatric low-grade glioma models: advances and ongoing challenges

Pediatric low-grade gliomas represent the most common childhood brain tumor class. While often curable, some tumors fail to respond and even successful treatments can have life-long side effects. Many clinical trials are underway for pediatric low-grade gliomas. However, these trials are expensive and challenging to organize due to the heterogeneity of patients and subtypes. Advances in sequencing technologies are helping to mitigate this by revealing the molecular landscapes of mutations in pediatric low-grade glioma. Functionalizing these mutations in the form of preclinical models is the next step in both understanding the disease mechanisms as well as for testing therapeutics. However, such models are often more difficult to generate due to their less proliferative nature, and the heterogeneity of tumor microenvironments, cell(s)-of-origin, and genetic alterations. In this review, we discuss the molecular and genetic alterations and the various preclinical models generated for the different types of pediatric low-grade gliomas. We examined the different preclinical models for pediatric low-grade gliomas, summarizing the scientific advances made to the field and therapeutic implications. We also discuss the advantages and limitations of the various models. This review highlights the importance of preclinical models for pediatric low-grade gliomas while noting the challenges and future directions of these models to improve therapeutic outcomes of pediatric low-grade gliomas.

The Neuroimmune Regulation and Potential Therapeutic Strategies of Optic Pathway Glioma

Optic pathway glioma (OPG) is one of the causes of pediatric visual impairment. Unfortunately, there is as yet no cure for such a disease. Understanding the underlying mechanisms and the potential therapeutic strategies may help to delay the progression of OPG and rescue the visual morbidities. Here, we provide an overview of preclinical OPG studies and the regulatory pathways controlling OPG pathophysiology. We next discuss the role of microenvironmental cells (neurons, T cells, and tumor-associated microglia and macrophages) in OPG development. Last, we provide insight into potential therapeutic strategies for treating OPG and promoting axon regeneration.

Neurofibromatosis- and schwannomatosis-associated tumors: Approaches to genetic testing and counseling considerations

Neurofibromatosis (NF) and schwannomatosis (SWN) are genetic conditions characterized by the risk of developing nervous system tumors. Recently revised diagnostic criteria include the addition of genetic testing to confirm a pathogenic variant, as well as to detect the presence of mosaicism. Therefore, the use and interpretation of both germline and tumor-based testing have increasing importance in the diagnostic approach, treatment decisions, and risk stratification of these conditions. This focused review discusses approaches to genetic testing of NF- and SWN-related tumor types, which are somewhat rare and perhaps lesser known to non-specialized clinicians. These include gastrointestinal stromal tumors, breast cancer, plexiform neurofibromas with or without transformation to malignant peripheral nerve sheath tumors, gliomas, and schwannomas, and emphasizes the need for inclusion of genetic providers in patient care and appropriate pre- and post-test education, genetic counseling, and focused evaluation by a medical geneticist or other healthcare provider familiar with clinical manifestations of these disorders.

The Role of Advanced MRI Sequences in the Diagnosis and Follow-Up of Adult Brainstem Gliomas: A Neuroradiological Review

The 2021 WHO (World Health Organization) classification of brain tumors incorporated the rapid advances in the molecular, genetic, and pathogenesis understanding of brain tumor pathogenesis, behavior, and treatment response. It revolutionized brain tumor classification by placing great emphasis on molecular types and completely splitting adult-type and pediatric-type diffuse gliomas. Brainstem gliomas (BSGs) are the leading primary tumors of the brainstem, although they are quite uncommon in adults compared with the pediatric population, representing less than 2% of adult gliomas. Surgery is not always the treatment of choice since resection is rarely feasible and does not improve overall survival, and biopsies are not generally performed since the location is treacherous. Therefore, MRI (Magnetic Resonance Imaging) without and with gadolinium administration represents the optimal noninvasive radiological technique to suggest brainstem gliomas diagnosis, plan a multidisciplinary treatment and for follow-up evaluations. The MRI protocol encompasses morphological sequences as well as functional and advanced sequences, such as DWI/ADC (Diffusion-Weighted Imaging/Apparent Diffusion Coefficient), DTI (Diffusion Tensor Imaging), PWI (Perfusion-Weighted Imaging), and MRS (Magnetic Resonance Spectroscopy), which improve the accuracy of the diagnosis of BSGs by adding substantial information regarding the cellularity, the infiltrative behavior toward the v fiber tracts, the vascularity, and the molecular changes. Brainstem gliomas have been divided into four categories on the basis of their MRI radiological appearance, including diffuse intrinsic low-grade gliomas, enhancing malignant gliomas, localized tectal gliomas, and other forms. The aim of our review is to provide insight into the role of advanced MRI sequences in the diagnosis and follow-up of adult brainstem gliomas.

Clinical, histological, and molecular features of gliomas in adults with neurofibromatosis type 1

BACKGROUND

People with NF1 have an increased prevalence of central nervous system malignancy. However, little is known about the clinical course or pathologic features of NF1-associated gliomas in adults, limiting clinical care and research.

METHODS

Adults (≥18 years) with NF1 and histologically confirmed non-optic pathway gliomas (non-OPGs) at Johns Hopkins Hospital, Memorial Sloan Kettering Cancer Center, and Washington University presenting between 1990 and 2020 were identified. Retrospective data were collated, and pathology was reviewed centrally.

RESULTS

Forty-five patients, comprising 23 females (51%), met eligibility criteria, with a median of age 37 (18-68 years) and performance status of 80% (30%-100%). Tissue was available for 35 patients. Diagnoses included infiltrating (low-grade) astrocytoma (9), glioblastoma (7), high-grade astrocytoma with piloid features (4), pilocytic astrocytoma (4), high-grade astrocytoma (3), WHO diagnosis not reached (4) and one each of gliosarcoma, ganglioglioma, embryonal tumor, and diffuse midline glioma. Seventy-one percent of tumors were midline and underwent biopsy only. All 27 tumors evaluated were IDH1-wild-type, independent of histology. In the 10 cases with molecular testing, the most common genetic variants were NF1, EGFR, ATRX, CDKN2A/B, TP53, TERT, and MSH2/3 mutation. While the treatments provided varied, the median overall survival was 24 months [2-267 months] across all ages, and 38.5 [18-109] months in individuals with grade 1-2 gliomas.

CONCLUSIONS

Non-OPGs in adults with NF1, including low-grade tumors, often have an aggressive clinical course, indicating a need to better understand the pathobiology of these NF1-associated gliomas.

Neurofibromatosis Type 1-Associated Optic Pathway Gliomas: Current Challenges and Future Prospects

Optic pathway glioma (OPG) occurs in as many as one-fifth of individuals with the neurofibromatosis type 1 (NF1) cancer predisposition syndrome. Generally considered low-grade and slow growing, many children with NF1-OPGs remain asymptomatic. However, due to their location within the optic pathway, ~20-30% of those harboring NF1-OPGs will experience symptoms, including progressive vision loss, proptosis, diplopia, and precocious puberty. While treatment with conventional chemotherapy is largely effective at attenuating tumor growth, it is not clear whether there is much long-term recovery of visual function. Additionally, because these tumors predominantly affect young children, there are unique challenges to NF1-OPG diagnosis, monitoring, and longitudinal management. Over the past two decades, the employment of authenticated genetically engineered Nf1-OPG mouse models have provided key insights into the function of the NF1 protein, neurofibromin, as well as the molecular and cellular pathways that contribute to optic gliomagenesis. Findings from these studies have resulted in the identification of new molecular targets whose inhibition blocks murine Nf1-OPG growth in preclinical studies. Some of these promising compounds have now entered into early clinical trials. Future research focused on defining the determinants that underlie optic glioma initiation, expansion, and tumor-induced optic nerve injury will pave the way to personalized risk assessment strategies, improved tumor monitoring, and optimized treatment plans for children with NF1-OPG.

Prevalence of Endocrine Manifestations and GIST in 108 Systematically Screened Patients With Neurofibromatosis Type 1

Context

In patients with neurofibromatosis type 1 (NF1), guidelines suggest screening for pheochromocytoma by metanephrine measurement and abdominal imaging, which may lead to the discovery of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) and their differential diagnosis, gastrointestinal stromal tumors (GISTs). Other endocrine manifestations such as follicular thyroid carcinoma and primary hyperparathyroidism have also been reported in a few cases.

Objective

This study aimed to describe prevalence and clinical presentation of these manifestations through systematic screening in a large cohort of patients.

Methods

In this monocentric retrospective study, 108 patients with NF1 were included and screened for endocrine manifestations and GISTs. Clinical, laboratory, molecular profile, pathology, and morphologic (abdominal computed tomography scan and/or magnetic resonance imaging) and functional imaging were collected.

Results

Twenty-four patients (22.2% of the cohort, 16 female, mean age 42.6 years) presented with pheochromocytomas that were unilateral in 65.5%, benign in 89.7%, and with a ganglioneural component in 20.7%. Three female patients (2.8% of the cohort, aged 42-63 years) presented with well-differentiated GEP-NETs, and 4 (3.7%) with GISTs. One patient had primary hyperparathyroidism, 1 patient had medullary microcarcinoma, and 16 patients had goiter, multinodular in 10 cases. There was no correlation between pheochromocytoma and other NF1 tumoral manifestations, nor correlations between pheochromocytoma and NF1 genotype, despite a familial clustering in one-third of patients.

Conclusion

The pheochromocytoma prevalence in this NF1 cohort was higher (>20%) than previously described, confirming the interest of systematic screening, especially in young women. The prevalence of GEP-NETs and GISTs was about 3%, respectively. No phenotype-genotype correlation was observed.

Clinicopathological and Immunohistochemistry Study of a Long Survivor of Giant Cell Glioblastoma in a Patient With Neurofibromatosis 1: Case Report

Glioblastoma multiforme (IDH wild type) is an aggressive glial tumor of astrocytic origin (WHO-grade 4) with a two-year median survival period. Patients who live more than three years are considered as long survivors. In this study, we present a long survivor of a known case of neurofibromatosis type 1 who developed GBM of the giant cell type at age 14 years, and now the patient, at age 28, has been cancer-free for more than 14 years.

The Congenital and Acquired Mechanisms Implicated in the Etiology of Central Precocious Puberty

The etiology of central precocious puberty (CPP) is multiple and heterogeneous, including congenital and acquired causes that can be associated with structural or functional brain alterations. All causes of CPP culminate in the premature pulsatile secretion of hypothalamic GnRH and, consequently, in the premature reactivation of hypothalamic-pituitary-gonadal axis. The activation of excitatory factors or suppression of inhibitory factors during childhood represent the 2 major mechanisms of CPP, revealing a delicate balance of these opposing neuronal pathways. Hypothalamic hamartoma (HH) is the most well-known congenital cause of CPP with central nervous system abnormalities. Several mechanisms by which hamartoma causes CPP have been proposed, including an anatomical connection to the anterior hypothalamus, autonomous neuroendocrine activity in GnRH neurons, trophic factors secreted by HH, and mechanical pressure applied to the hypothalamus. The importance of genetic and/or epigenetic factors in the underlying mechanisms of CPP has grown significantly in the last decade, as demonstrated by the evidence of genetic abnormalities in hypothalamic structural lesions (eg, hamartomas, gliomas), syndromic disorders associated with CPP (Temple, Prader-Willi, Silver-Russell, and Rett syndromes), and isolated CPP from monogenic defects (MKRN3 and DLK1 loss-of-function mutations). Genetic and epigenetic discoveries involving the etiology of CPP have had influence on the diagnosis and familial counseling providing bases for potential prevention of premature sexual development and new treatment targets in the future. Global preventive actions inducing healthy lifestyle habits and less exposure to endocrine-disrupting chemicals during the lifespan are desirable because they are potentially associated with CPP.

Neurofibromatosis Type 1: Pediatric Aspects and Review of Genotype-Phenotype Correlations

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition, with a birth incidence of approximately 1:2000-3000, caused by germline pathogenic variants in NF1, a tumor suppressor gene encoding neurofibromin, a negative regulator of the RAS/MAPK pathway. This explains why NF1 is included in the group of RASopathies and shares several clinical features with Noonan syndrome. Here, we describe the main clinical characteristics and complications associated with NF1, particularly those occurring in pediatric age. NF1 has complete penetrance and shows wide inter- and intrafamilial phenotypic variability and age-dependent appearance of manifestations. Clinical presentation and history of NF1 are multisystemic and highly unpredictable, especially in the first years of life when penetrance is still incomplete. In this scenario of extreme phenotypic variability, some genotype-phenotype associations need to be taken into consideration, as they strongly impact on genetic counseling and prognostication of the disease. We provide a synthetic review, based on the most recent literature data, of all known genotype-phenotype correlations from a genetic and clinical perspective. Molecular diagnosis is fundamental for the confirmation of doubtful clinical diagnoses, especially in the light of recently revised diagnostic criteria, and for the early identification of genotypes, albeit few, that correlate with specific phenotypes.

Evaluation of the sense of taste and smell in patients with Neurofibromatosis Type 1

OBJECTIVE

The objective of this study was to determine if patients with Neurofibromatosis Type 1 (NF1) have an impaired sense of smell or taste. Neurofibromin, the NF1gene protein product is ubiquitous in the body and is especially associated with the development of neurogenetic structures. Lately enlarged olfactory bulbs have been described in patients with NF1. Until now, there is no study to evaluate the sense of smell and taste in patients with NF1.

METHOD

This study has been approved by the Hamburg Ethics committee. An evaluation of the sense of smell and taste was undertaken in 26 patients with NF1 using the Burghart Sniffin' Sticks. Three patients were excluded due to a prior infection with the Corona virus. As a control group the same examination was performed in healthy individuals (same sex/ same age as the NF1 patients) by the same examiner.

RESULTS

The results show a normal sense of smell in patients with NF1. The morphologic finding of enlarged olfactory bulbs seem to have no functional equivalent. However, 8 out of 23 patients with NF1 had difficulties identifying at least one taste flavor. In total 9.8% of possible taste qualities were misidentified. In the healthy control group, all taste qualities were identified correctly. Considering each taste quality as separate case, a significant difference in the taste function was identified based on Fisher's exact test (p=0.003).

CONCLUSION

The current study does not show a correlation between NF1 and an impaired sense of smell. Yet significant reduction in the sense of taste was found in the patients with NF1. Further research will have to be conducted to find the underlying causal pathways.

CLINICAL RELEVANCE

NF1 is recently being acknowledged not only for its' macroscopic aesthetic and functional impairments, but also as a neurodevelopmental disorder. Evaluating the neural structures in regard to their function is a first step in understanding more about the disease.

ERN GENTURIS tumour surveillance guidelines for individuals with neurofibromatosis type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a multisystem genetic disorder, predisposing development of benign and malignant tumours. Given the oncogenic potential, long-term surveillance is important in patients with NF1. Proposals for NF1 care and its specific manifestations have been developed, but lack integration within routine care. This guideline aims to assimilate available information on NF1 associated tumours (based on evidence and/or expert opinion) to assist healthcare professionals in undertaking tumour surveillance of NF1 individuals.

METHODS

By comprehensive literature review, performed March 18th 2020, guidelines were developed by a NF1 expert group and patient representatives, conversant with clinical care of the wide NF1 disease spectrum. We used a modified Delphi procedure to overcome issues of variability in recommendations for specific (national) health care settings, and to deal with recommendations based on indirect (scarce) evidence.

FINDINGS

We defined proposals for personalised and targeted tumour management in NF1, ensuring appropriate care for those in need, whilst reducing unnecessary intervention. We also incorporated the tumour-related psychosocial and quality of life impact of NF1.

INTERPRETATION

The guideline reflects the current care for NF1 in Europe. They are not meant to be prescriptive and may be adjusted to local available resources at the treating centre, both within and outside EU countries.

FUNDING

This guideline has been supported by the European Reference Network on Genetic Tumour Risk Syndromes (ERN GENTURIS). ERN GENTURIS is funded by the European Union. DGE is supported by the Manchester NIHRBiomedical Research Centre (IS-BRC-1215-20007).

Neurons as stromal drivers of nervous system cancer formation and progression

Similar to their pivotal roles in nervous system development, neurons have emerged as critical regulators of cancer initiation, maintenance, and progression. Focusing on nervous system tumors, we describe the normal relationships between neurons and other cell types relevant to normal nerve function, and discuss how disruptions of these interactions promote tumor evolution, focusing on electrical (gap junctions) and chemical (synaptic) coupling, as well as the establishment of new paracrine relationships. We also review how neuron-tumor communication contributes to some of the complications of cancer, including neuropathy, chemobrain, seizures, and pain. Finally, we consider the implications of cancer neuroscience in establishing risk for tumor penetrance and in the design of future anti-tumoral treatments.

Pediatric low-grade glioma and neurofibromatosis type 1: A single-institution experience

Background

Neurofibromatosis type 1 (NF1)-related gliomas appear to have a clinical behavior different from that of sporadic cases. The purpose of the study was to investigate the role of different factors in influencing the tumor response rate of children receiving chemotherapy for their symptomatic glioma.

Methods

Between 1995 and 2015, 60 patients with low-grade glioma (42 sporadic cases and 18 cases with NF1) were treated. Patients with brainstem gliomas were excluded. Thirty-nine patients underwent exclusive or postsurgical chemotherapy (vincristine/carboplatin-based regimen).

Results

Disease reduction was achieved in 12 of the 28 patients (42.8%) with sporadic low-grade glioma and in 9 of the 11 patients (81.8%) with NF1, with a significant difference between the 2 groups (P < 0.05). The response to chemotherapy in both the patient groups was not significantly influenced by sex, age, tumor site, and histopathology, although disease reduction occurred more frequently in children aged under 3 years.

Conclusions

Our study showed that pediatric patients with low-grade glioma and NF1 are more likely to respond to chemotherapy than those with non-NF1.

Cost Analysis of Orthoptist-Led Neurofibromatosis Type 1 Screening Clinics

Purpose

To conduct a costing study comparing orthoptist-led with consultant-led clinics screening for optic pathway gliomas (OPGs) in children with neurofibromatosis Type 1 (NF1) attending the Royal Children's Hospital (RCH), Melbourne.

Methods

Patients with NF1 examined in the orthoptist-led NF1 screening clinic and/or consultant-led clinics during the study period were identified. The workflow management software Q-Flow 6® provided data documenting patient's time spent with the orthoptist, nurse, and ophthalmologist. Time points were converted into minutes and multiplied by the cost-per-minute for each profession. A bottom-up micro-costing approach was used to estimate appointment level costs. Bootstrap simulations with 1000 replications were used to estimate 95% confidence intervals (CIs) for the difference in mean appointment time and cost between clinics.

Results

Data for 130 consultant-led clinic appointments and 234 orthoptist-led clinic appointments were extracted for analysis. The mean time per appointment for the consultant-led clinic was 45.11 minutes, and the mean time per appointment for the orthoptist-led clinic was 25.85 minutes. The mean cost per appointment for the consultant-led clinic was A $84.15 (GBP £39.60) compared to the orthoptist-led clinic at A $20.40 (GBP £9.60). This represents a mean reduction of 19.25 minutes per appointment (95% CI, -24.85 to -13.66) and a mean reduction of A $63.75 (GBP £30.00) per appointment (95% CI, (A $-75.40 to $-52.10 [GBP £ -35.48 to £ -24.52]).

Conclusion

An orthoptist-led clinic screening for OPGs in patients with NF1 can be a more cost-efficient model of care for ophthalmic screening in this patient group.

A new era for optic pathway glioma: A developmental brain tumor with life-long health consequences

Optic pathway and hypothalamic glioma (OPHG) are low-grade brain tumors that arise from any part of the visual pathways frequently involving the hypothalamus. The tumors grow slowly and present with features driven by their precise anatomical site, their age at presentation and the stage of growth and development of the host neural and orbital bony tissues. Up to 50% of optic pathway glioma arise in association with Neurofibromatosis type 1 (NF1), which affects 1 in 3,000 births and is a cancer predisposition syndrome. As low-grade tumors, they almost never transform to malignant glioma yet they can threaten life when they present under two years of age. The main risks are to threaten vision loss by progressive tumor damage to optic pathways; furthermore, invasion of the hypothalamus can lead to diencephalic syndrome in infancy and hypopituitarism later in life. Progressive cognitive and behavioural dysfunction can occur, as part of NF1 syndromic features and in sporadic cases where large bulky tumors compress adjacent structures and disrupt neuro-hypothalamic pathways. Persistently progressive tumors require repeated treatments to attempt to control vision loss, other focal brain injury or endocrine dysfunction. In contrast tumors presenting later in childhood can be seen to spontaneously arrest in growth and subsequently progress after periods of stability. These patterns are influenced by NF status as well as stages of growth and development of host tissues. The past two decades has seen an expansion in our understanding and knowledge of the clinical and scientific features of these tumors, their modes of presentation, the need for careful visual and endocrine assessment. This influences the decision-making surrounding clinical management with surgery, radiotherapy, chemotherapy and most recently, the potential benefit of molecularly targeted drug therapy. This article, based upon the authors' clinical and research experience and the published literature will highlight advances in approach to diagnosis, the established role of vision loss as justification of treatments and the emerging evidence of endocrine and neurological consequences that need to be incorporated into judgements for case selection for therapy or observation. Consideration is given to the current state of biological evidence justifying current trials of new therapies, the genetic studies of the NF1 gene and the potential for new approaches to OPHG detection and treatment. The outstanding health system priorities from the perspective of children, their parents and health system commissioners or insurers are discussed.

Multiplatform molecular analyses refine classification of gliomas arising in patients with neurofibromatosis type 1

Gliomas arising in the setting of neurofibromatosis type 1 (NF1) are heterogeneous, occurring from childhood through adulthood, can be histologically low-grade or high-grade, and follow an indolent or aggressive clinical course. Comprehensive profiling of genetic alterations beyond NF1 inactivation and epigenetic classification of these tumors remain limited. Through next-generation sequencing, copy number analysis, and DNA methylation profiling of gliomas from 47 NF1 patients, we identified 2 molecular subgroups of NF1-associated gliomas. The first harbored biallelic NF1 inactivation only, occurred primarily during childhood, followed a more indolent clinical course, and had a unique epigenetic signature for which we propose the terminology "pilocytic astrocytoma, arising in the setting of NF1". The second subgroup harbored additional oncogenic alterations including CDKN2A homozygous deletion and ATRX mutation, occurred primarily during adulthood, followed a more aggressive clinical course, and was epigenetically diverse, with most tumors aligning with either high-grade astrocytoma with piloid features or various subclasses of IDH-wildtype glioblastoma. Several patients were treated with small molecule MEK inhibitors that resulted in stable disease or tumor regression when used as a single agent, but only in the context of those tumors with NF1 inactivation lacking additional oncogenic alterations. Together, these findings highlight recurrently altered pathways in NF1-associated gliomas and help inform targeted therapeutic strategies for this patient population.

Human induced pluripotent stem cell engineering establishes a humanized mouse platform for pediatric low-grade glioma modeling

A major obstacle to identifying improved treatments for pediatric low-grade brain tumors (gliomas) is the inability to reproducibly generate human xenografts. To surmount this barrier, we leveraged human induced pluripotent stem cell (hiPSC) engineering to generate low-grade gliomas (LGGs) harboring the two most common pediatric pilocytic astrocytoma-associated molecular alterations, NF1 loss and KIAA1549:BRAF fusion. Herein, we identified that hiPSC-derived neuroglial progenitor populations (neural progenitors, glial restricted progenitors and oligodendrocyte progenitors), but not terminally differentiated astrocytes, give rise to tumors retaining LGG histologic features for at least 6 months in vivo. Additionally, we demonstrated that hiPSC-LGG xenograft formation requires the absence of CD4 T cell-mediated induction of astrocytic Cxcl10 expression. Genetic Cxcl10 ablation is both necessary and sufficient for human LGG xenograft development, which additionally enables the successful long-term growth of patient-derived pediatric LGGs in vivo. Lastly, MEK inhibitor (PD0325901) treatment increased hiPSC-LGG cell apoptosis and reduced proliferation both in vitro and in vivo. Collectively, this study establishes a tractable experimental humanized platform to elucidate the pathogenesis of and potential therapeutic opportunities for childhood brain tumors.

The Current State of Radiotherapy for Pediatric Brain Tumors: An Overview of Post-Radiotherapy Neurocognitive Decline and Outcomes

Tumors of the central nervous system are the most common solid malignancies diagnosed in children. While common, they are also found to have some of the lowest survival rates of all malignancies. Treatment of childhood brain tumors often consists of operative gross total resection with adjuvant chemotherapy or radiotherapy. The current body of literature is largely inconclusive regarding the overall benefit of adjuvant chemo- or radiotherapy. However, it is known that both are associated with conditions that lower the quality of life in children who undergo those treatments. Chemotherapy is often associated with nausea, emesis, significant fatigue, immunosuppression, and alopecia. While radiotherapy can be effective for achieving local control, it is associated with late effects such as endocrine dysfunction, secondary malignancy, and neurocognitive decline. Advancements in radiotherapy grant both an increase in lifetime survival and an increased lifetime for survivors to contend with these late effects. In this review, the authors examined all the published literature, analyzing the results of clinical trials, case series, and technical notes on patients undergoing radiotherapy for the treatment of tumors of the central nervous system with a focus on neurocognitive decline and survival outcomes.

Ten-year survival in glioblastoma patient with neurofibromatosis type 1: illustrative case

BACKGROUND

Gliomas are commonly detected in patients with neurofibromatosis type 1 (NF1) at an early age. Few patients with NF1 are diagnosed with glioblastoma. The course of management, response to therapy, and prognosis of such patients are unknown. Few reports have shown longer-than-average survival rates for patients with NF1 with glioblastoma.

OBSERVATIONS

A 27-year-old man with NF1 presented with symptoms of high intracranial pressure. Imaging and pathology showed left frontotemporal glioblastoma. Gross total resection was achieved, and concurrent chemoradiotherapy was administered. Recurrence of tumor was detected 48 months later, and the patient underwent tumor debulking and concurrent chemoradiotherapy. The patient received first-, second-, and third-line chemotherapy (temozolomide, bevacizumab, bevacizumab/irinotecan) with good tolerance and has survived >10 years since then with good functional status.

LESSONS

This case demonstrates >10 years overall survival of glioblastoma in a patient with NF1. Reports of patients with NF1 with longer survival may be attributed to the young age at diagnosis and relatively better tolerance for therapy. It might also support the growing evidence of a unique subset of glioblastoma associated with NF1 and opens the door for a more molecular targeted therapy in the future.

NF1 optic pathway glioma: analyzing risk factors for visual outcome and indications to treat

BACKGROUND

The aim of the project was to identify risk factors associated with visual progression and treatment indications in pediatric patients with neurofibromatosis type 1 associated optic pathway glioma (NF1-OPG).

METHODS

A multidisciplinary expert group consisting of ophthalmologists, pediatric neuro-oncologists, neurofibromatosis specialists, and neuro-radiologists involved in therapy trials assembled a cohort of children with NF1-OPG from 6 European countries with complete clinical, imaging, and visual outcome datasets. Using methods developed during a consensus workshop, visual and imaging data were reviewed by the expert team and analyzed to identify associations between factors at diagnosis with visual and imaging outcomes.

RESULTS

Eighty-three patients (37 males, 46 females, mean age 5.1 ± 2.6 y; 1-13.1 y) registered in the European treatment trial SIOP LGG-2004 (recruited 2004-2012) were included. They were either observed or treated (at diagnosis/after follow-up).In multivariable analysis, factors present at diagnosis associated with adverse visual outcomes included: multiple visual signs and symptoms (adjusted odds ratio [adjOR]: 8.33; 95% CI: 1.9-36.45), abnormal visual behavior (adjOR: 4.15; 95% CI: 1.20-14.34), new onset of visual symptoms (adjOR: 4.04; 95% CI: 1.26-12.95), and optic atrophy (adjOR: 3.73; 95% CI: 1.13-12.53). Squint, posterior visual pathway tumor involvement, and bilateral pathway tumor involvement showed borderline significance. Treatment appeared to reduce tumor size but improved vision in only 10/45 treated patients. Children with visual deterioration after primary observation are more likely to improve with treatment than children treated at diagnosis.

CONCLUSIONS

The analysis identified the importance of symptomatology, optic atrophy, and history of vision loss as predictive factors for poor visual outcomes in children with NF1-OPG.

Implications of new understandings of gliomas in children and adults with NF1: report of a consensus conference

Gliomas are the most common primary central nervous system tumors occurring in children and adults with neurofibromatosis type 1 (NF1). Over the past decade, discoveries of the molecular basis of low-grade gliomas (LGGs) have led to new approaches for diagnosis and treatments. However, these new understandings have not been fully applied to the management of NF1-associated gliomas. A consensus panel consisting of experts in NF1 and gliomas was convened to review the current molecular knowledge of NF1-associated low-grade “transformed” and high-grade gliomas; insights gained from mouse models of NF1-LGGs; challenges in diagnosing and treating older patients with NF1-associated gliomas; and advances in molecularly targeted treatment and potential immunologic treatment of these tumors. Next steps are recommended to advance the management and outcomes for NF1-associated gliomas.

An Unusual Association between Neurofibromatosis Type 1 and Diffuse B Cell Lymphoma

Neurofibromatosis type 1 (NF-1) is known to be associated with increased risk of malignancy by at least fourfold. Malignant lymphomas are rare in adults with NF-1. Hereby, we present a 75-year-old male with NF-1 complaining of weakness, nausea, and vomiting associated with abdominal pain. Three months prior to presentation, he had suffered a motor vehicle accident (MVA) resulting in multiple rib fractures that was seen in chest X-ray. For the following three months, he had intermittent chest pain, but it was attributed to the recent rib fracture. During this admission, the severity of chest pain worsened and the associated vomiting inclined further investigation; including CT imaging and bone biopsy, it was revealed to be a rare case of diffuse B cell lymphoma in a patient with NF-1. However, we believe the recent MVA caused an anchoring bias in making a prompt diagnosis. In addition, the appearance of the neurofibroma, resulted in suboptimal physical examination, and hence, there was a delay in reaching the diagnosis. We will discuss here the presentation of this case, to highlight the rare association and to increase awareness of when encountering a challenging diagnosis.

Case Report: Chemotherapy Indication in a Case of Neurofibromatosis Type 1 Presenting Optic Pathway Glioma: A One-Year Clinical Case Study Using Differential Tractography Approach

Neurofibromatosis type 1 (NF1) is associated with peripheral and central nervous system tumors. It is noteworthy that the regions in which these tumors frequently arise are the optic pathways (OPs) and the brainstem. Thus, we decided to trace the procedure of diffusion Magnetic Resonance Imaging (dMRI) alterations along with Short-Wavelength Automated Perimetry (SWAP) examinations of the OPs after surgery and chemotherapy over 1 year, which enabled us to evaluate chemotherapy's efficacy in an NF1 patient with an OP tumor. In this study, a 25-year-old woman with NF1 and left optic radiation (OR) glioma underwent surgery to remove the glioma. Immunohistochemistry (IHC) revealed a Pilocytic Astrocytoma (PA) WHO grade I. Post-operation chemotherapy done using nine treatment cycles of administering Temozolomide (TMZ) for 5 days every 4 weeks. Applying the region of interest (ROI) differential tractography method and SWAP four times every 3 months allowed us to follow the patient's visual acuity alterations longitudinally. The differential deterministic tractography method and statistical analyses enabled us to discover the white matter (WM) tracts anisotropy alterations over time. Furthermore, statistical analyses on the SWAP results along time illustrated possible alterations in visual acuity. Then, we could compare and associate the findings with the SWAP examinations and patient symptoms longitudinally. Statistical analyses of SWAP tests revealed a significant improvement in visual fields, and longitudinal differential tractography showed myelination and dense axonal packing in the left OR after 1 year of treatment. In this study, we examined an old hypothesis suggesting that chemotherapy is more effective than radiotherapy for NF1 patients with OP gliomas (OPGs) because of the radiation side effects on the visual field, cognition, and cerebrovascular complications. Our longitudinal clinical case study involving dMRI and SWAP on a single NF1-OPG patient showed that chemotherapy did not suppress the OP myelination over time. However, it should be noted that this is a clinical case study, and, therefore, the generalization of results is limited. Future investigations might focus on genetic-based imaging, particularly in more cases. Further, meta-analyses are recommended for giving a proper Field Of View (FOV) to researchers as a subtle clue regarding precision medicine.

Molecular Characterization of Medulloblastoma in a Patient with Neurofibromatosis Type 1: Case Report and Literature Review

Brain tumors are the most common solid neoplasms of childhood. They are frequently reported in children with Neurofibromatosis type 1 (NF1). The most frequent central nervous system malignancies described in NF1 are optic pathway gliomas and brainstem gliomas. Medulloblastoma (MB) in NF1 patients is extremely rare, and to our knowledge, only 10 cases without molecular characterization are described in the literature to date. We report the case of a 14-year-old girl with NF1 that came to our attention for an incidental finding of a lesion arising from cerebellar vermis. The mass was completely resected, revealing a localized classic medulloblastoma (MB), subgroup 4. She was treated as a standard-risk MB with a dose-adapted personalized protocol. The treatment proved to be effective, with minor toxicity. Brain and spine MRI one year after diagnosis confirmed the complete remission of the disease. To our knowledge, this is the only case of MB reported in a patient with NF1 with molecular characterization by the methylation profile. The association between NF1 and MB, although uncommon, may not be an accidental occurrence.

Integrated molecular and clinical analysis of low-grade gliomas in children with neurofibromatosis type 1 (NF1)

Low-grade gliomas (LGGs) are the most common childhood brain tumor in the general population and in individuals with the Neurofibromatosis type 1 (NF1) cancer predisposition syndrome. Surgical biopsy is rarely performed prior to treatment in the setting of NF1, resulting in a paucity of tumor genomic information. To define the molecular landscape of NF1-associated LGGs (NF1-LGG), we integrated clinical data, histological diagnoses, and multi-level genetic/genomic analyses on 70 individuals from 25 centers worldwide. Whereas, most tumors harbored bi-allelic NF1 inactivation as the only genetic abnormality, 11% had additional mutations. Moreover, tumors classified as non-pilocytic astrocytoma based on DNA methylation analysis were significantly more likely to harbor these additional mutations. The most common secondary alteration was FGFR1 mutation, which conferred an additional growth advantage in multiple complementary experimental murine Nf1 models. Taken together, this comprehensive characterization has important implications for the management of children with NF1-LGG, distinct from their sporadic counterparts.

Longitudinal Assessment of Enhancing Foci of Abnormal Signal Intensity in Neurofibromatosis Type 1

BACKGROUND AND PURPOSE

Patients with neurofibromatosis 1 are at increased risk of developing brain tumors, and differentiation from contrast-enhancing foci of abnormal signal intensity can be challenging. We aimed to longitudinally characterize rare, enhancing foci of abnormal signal intensity based on location and demographics.

MATERIALS AND METHODS

A total of 109 MR imaging datasets from 19 consecutive patients (7 male; mean age, 8.6 years; range, 2.3-16.8 years) with neurofibromatosis 1 and a total of 23 contrast-enhancing parenchymal lesions initially classified as foci of abnormal signal intensity were included. The mean follow-up period was 6.5 years (range, 1-13.8 years). Enhancing foci of abnormal signal intensity were followed up with respect to presence, location, and volume. Linear regression analysis was performed.

RESULTS

Location, mean peak volume, and decrease in enhancing volume over time of the 23 lesions were as follows: 10 splenium of the corpus callosum (295 mm³, 5 decreasing, 3 completely resolving, 2 surgical intervention for change in imaging appearance later confirmed to be gangliocytoma and astrocytoma WHO II), 1 body of the corpus callosum (44 mm³, decreasing), 2 frontal lobe white matter (32 mm³, 1 completely resolving), 3 globus pallidus (50 mm³, all completely resolving), 6 cerebellum (206 mm³, 3 decreasing, 1 completely resolving), and 1 midbrain (34 mm³). On average, splenium lesions began to decrease in size at 12.2 years, posterior fossa lesions at 17.1 years, and other locations at 9.4 years of age.

CONCLUSIONS

Albeit very rare, contrast-enhancing lesions in patients with neurofibromatosis 1 may regress over time. Follow-up MR imaging aids in ascertaining regression. The development of atypical features should prompt further evaluation for underlying tumors.

Modality of Radiotherapy and Overall Survival in Pediatric Diffuse Brainstem Gliomas: Implications for Resource-Constrained Settings

BACKGROUND

Childhood diffuse brainstem glioma (dBSG) is a rare tumor with a poor prognosis. Any tumor-directed surgical intervention is difficult. Magnetic resonance imaging forms the mainstay of diagnosis and radiation therapy has remained the backbone of therapy. In this study, we compare the outcomes of conformal radiotherapy with conventional therapy in the context of resource-constrained settings.

METHODS

In this retrospective analysis, conducted between 2010 and 2019, all pediatric patients with a diagnosis of dBSG were analyzed. The survival data were calculated in months from the date of diagnosis. Survival differences between variables were compared using the Log-rank test and the risk of death was calculated using Cox regression analysis.

RESULTS

A total of 20 patients (11 males, 55%) with a diagnosis of dBSG were included. Median age at diagnosis was 6.5 years. No surgical resection or biopsy was done in any patient. Fifteen (75%) patients received radiotherapy and only 4 (20%) patients received additional chemotherapy. Five (25%) patients did not receive any form of anti-cancer therapy. Median overall survival (OS) was 8 months (95% CI 5.2-10.8). Females were at a higher risk of death than males. Children treated with radiotherapy had a longer OS than untreated children; however, the modality of radiotherapy employed or the addition of chemotherapy did not affect the OS.

CONCLUSION

Radiotherapy, irrespective of the modality, increases the survival of children with dBSG in resource-poor settings. Additionally, socioeconomic concerns need to be addressed in the management of these tumors, especially in the case of female children. Lay summaryChildhood diffuse brainstem glioma (dBSG) is a rare tumor with a poor prognosis. Any tumor-directed surgical intervention is difficult. Magnetic resonance imaging forms the mainstay of diagnosis and radiation therapy has remained the backbone of therapy. In this 10-year retrospective study, we compare the outcomes of conformal radiotherapy with conventional therapy in the context of resource-constrained settings. A total of 20 patients with a diagnosis of dBSG were included with a median age at diagnosis of 6.5 years (5.25-8.75). No surgical resection or biopsy was done in any patient. Fifteen (75%) patients received radiotherapy and only 4 (20%) patients received additional chemotherapy. Five (25%) patients did not receive any form of anti-cancer therapy. Median overall survival (OS) was 8 months (95% CI 5.2-10.8). Females were at a 3.4-fold (95% CI 1.0-12.1) higher risk of death than males. Children treated with radiotherapy had a longer OS than untreated children; however, the modality of radiotherapy employed or the addition of chemotherapy did not affect the OS. Radiotherapy, irrespective of the modality, increases the survival of children with dBSG in resource-poor settings. Additionally, socioeconomic concerns need to be addressed in the management of these tumors, especially in the case of female children.

Cutaneous Findings in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a complex autosomal dominant disorder associated with germline mutations in the NF1 tumor suppressor gene. NF1 belongs to a class of congenital anomaly syndromes called RASopathies, a group of rare genetic conditions caused by mutations in the Ras/mitogen-activated protein kinase pathway. Generally, NF1 patients present with dermatologic manifestations. In this review the main features of café-au-lait macules, freckling, neurofibromas, juvenile xanthogranuloma, nevus anemicus and other cutaneous findings will be discussed.

Selumetinib normalizes Ras/MAPK signaling in clinically relevant neurofibromatosis type 1 minipig tissues in vivo

BACKGROUND

The MEK1/2 inhibitor selumetinib was recently approved for neurofibromatosis type 1 (NF1)-associated plexiform neurofibromas, but outcomes could be improved and its pharmacodynamic evaluation in other relevant tissues is limited. The aim of this study was to assess selumetinib tissue pharmacokinetics (PK) and pharmacodynamics (PD) using a minipig model of NF1.

METHODS

WT (n = 8) and NF1 (n = 8) minipigs received a single oral dose of 7.3 mg/kg selumetinib. Peripheral blood mononuclear cells (PBMCs), cerebral cortex, optic nerve, sciatic nerve, and skin were collected for PK analysis and PD analysis of extracellular regulated kinase phosphorylation (p-ERK) inhibition and transcript biomarkers (DUSP6 & FOS).

RESULTS

Key selumetinib PK parameters aligned with those observed in human patients. Selumetinib concentrations were higher in CNS tissues from NF1 compared to WT animals. Inhibition of ERK phosphorylation was achieved in PBMCs (mean 60% reduction), skin (95%), and sciatic nerve (64%) from all minipigs, whereas inhibition of ERK phosphorylation in cerebral cortex was detected only in NF1 animals (71%). Basal p-ERK levels were significantly higher in NF1 minipig optic nerve compared to WT and were reduced to WT levels (60%) with selumetinib. Modulation of transcript biomarkers was observed in all tissues.

CONCLUSIONS

Selumetinib reduces MAPK signaling in tissues clinically relevant to NF1, effectively normalizing p-ERK to WT levels in optic nerve but resulting in abnormally low levels of p-ERK in the skin. These results suggest that selumetinib exerts activity in NF1-associated CNS tumors by normalizing Ras/MAPK signaling and may explain common MEK inhibitor-associated dermatologic toxicities.

Current Salvage Treatment Strategies for Younger Children (<10 y of Age) With Progressive Low-grade Glioma After Initial Chemotherapy in North America: A Web-based Survey

Pediatric low-grade gliomas (LGGs) are the most common brain tumors in children. Treatment of pediatric LGG can often be challenging, particularly when not resectable and refractory or recurrent following standard chemotherapy regimens. There is no current accepted standard of care salvage regimen for progressive LGG after the failure of first-line chemotherapy. A web-based survey was distributed to pediatric cancer centers throughout North America to inquire regarding institutional preferences of salvage treatment strategies after initial chemotherapy for LGG in children less than 10 years of age, as well as molecular testing preferences. Highlights from the survey results were as follows: vincristine/carboplatin (VC) and vinblastine (VBL) were the top 2 preferred salvage regimens for non-BRAF-altered pediatric LGG. BRAF and MEK inhibitors were the most preferred salvage regimens for BRAF V600e-mutated and BRAF fusion-positive pediatric LGG, respectively. VC ranked second. As high as 47.8% of North American centers would use conformal radiation for younger children with non-neurofibromatosis type 1 LGG after failing 2 to 3 chemotherapy regimens. Overall, 87% (87%) of North American institutions obtain some type of routine molecular testing for non-neurofibromatosis type 1-associated pediatric LGG cases. Less than 60% of centers obtain routine H3 K27M molecular testing for pediatric LGG with a midline location.

Familial Nervous System Tumor Syndromes

PURPOSE OF REVIEW

Although sporadic primary neoplasms account for the majority of nervous system tumors, familial nervous system tumor syndromes are important and clinically relevant conditions for the neurologist to understand. This article reviews common inherited nervous system tumor syndromes including neurofibromatosis type 1, neurofibromatosis type 2, schwannomatosis, tuberous sclerosis complex, and von Hippel-Lindau syndrome. The epidemiology, genetics, approach to diagnosis, neurologic and nonneurologic manifestations, and management options are reviewed.

RECENT FINDINGS

Awareness of the more common and clinically relevant familial nervous system tumor syndromes is important. These conditions teach us about the underlying biology that drives tumor development in the central and peripheral nervous systems including peripheral nerve sheath tumors (eg, neurofibroma, schwannoma), meningioma, vestibular schwannoma, subependymal giant cell astrocytoma, and hemangioblastoma. Knowledge of the clinical manifestations ensures that the neurologist will be able to diagnose these conditions, recommend appropriate surveillance, refer to specialists, and support optimal management. Important discoveries in the role of the underlying genetics have contributed to the launch of several novel drug trials for these tumors, which are changing therapeutic options for patients.

SUMMARY

Familial nervous system tumor syndromes are uncommon conditions that require specialized surveillance and management strategies. Coordination across a multidisciplinary team that includes neurologists, neuro-oncologists, radiologists, neurosurgeons, radiation oncologists, otolaryngologists, pathologists, neuropsychologists, physical medicine and rehabilitation specialists, and geneticists is necessary for the optimal treatment of these patients.

Clinical characterization of children and adolescents with NF1 microdeletions

PURPOSE

An estimated 5-11% of patients with neurofibromatosis type 1 (NF1) harbour NF1 microdeletions encompassing the NF1 gene and its flanking regions. The purpose of this study was to evaluate the clinical phenotype in children and adolescents with NF1 microdeletions.

METHODS

We retrospectively analysed 30 children and adolescents with NF1 microdeletions pertaining to externally visible neurofibromas. The internal tumour load was determined by volumetry of whole-body magnetic resonance imaging (MRI) in 20 children and adolescents with NF1 microdeletions. Furthermore, the prevalence of global developmental delay, autism spectrum disorder and attention deficit hyperactivity disorder (ADHD) were evaluated.

RESULTS

Children and adolescents with NF1 microdeletions had significantly more often cutaneous, subcutaneous and externally visible plexiform neurofibromas than age-matched patients with intragenic NF1 mutations. Internal neurofibromas were detected in all 20 children and adolescents with NF1 microdeletions analysed by whole-body MRI. By contrast, only 17 (61%) of 28 age-matched NF1 patients without microdeletions had internal tumours. The total internal tumour load was significantly higher in NF1 microdeletion patients than in NF1 patients without microdeletions. Global developmental delay was observed in 28 (93%) of 30 children with NF1 microdeletions investigated. The mean full-scale intelligence quotient in our patient group was 77.7 which is significantly lower than that of patients with intragenic NF1 mutations. ADHD was diagnosed in 15 (88%) of 17 children and adolescents with NF1 microdeletion. Furthermore, 17 (71%) of the 24 patients investigated had T-scores ≥ 60 up to 75, indicative of mild to moderate autistic symptoms, which are consequently significantly more frequent in patients with NF1 microdeletions than in the general NF1 population. Also, the mean total T-score was significantly higher in patients with NF1 microdeletions than in the general NF1 population.

CONCLUSION

Our findings indicate that already at a very young age, NF1 microdeletions patients frequently exhibit a severe disease manifestation which requires specialized long-term clinical care.

Genetic basis of neurofibromatosis type 1 and related conditions, including mosaicism

INTRODUCTION

Neurofibromatosis type 1 (NF1) is a frequent autosomal dominant disorder characterised by café-au-lait maculae (CALM), skinfold freckling, iris Lisch nodules and benign peripheral nerve sheath tumours (neurofibromas).

MECHANISM

The NF1 gene is a tumour suppressor gene and NF1 individuals have an increased risk for a long list of tumours, all resulting from a second hit in the normal copy of the NF1 gene. Remarkably, some non-tumour phenotypes such as CALM and pseudarthrosis are also caused by a "second hit". Germline mutations inactivating the NF1 gene show a large variability in genetic mechanisms ranging from single-nucleotide substitutions and somatic mosaicism to large deletions affecting neighbouring genes. Molecular confirmation of the clinical diagnosis is becoming increasingly more important to differentiate NF1 from other syndromes such as Legius syndrome, to investigate genotype-phenotype correlations relevant in 10% of cases and to detect somatic mosaicism.

SURVEILLANCE AND THERAPY

Some degree of learning difficulties, attention deficit and social problems are observed in most children and affect quality of life. There is a large individual variability in complications and the evolution of the disease is difficult to predict. Specialised outpatient clinics for children have been widely established and are important for surveillance and guidance. Regular surveillance is also important for adolescents and adults because many tumour complications can be detected by whole-body MRI and treated even before symptoms develop and irreversible damage occurs. Recent data on nodular plexiform neurofibromas with continued growth in adolescents and young adults show that many of these tumours are premalignant lesions called atypical neurofibromatous neoplasm of uncertain biological potential (ANNUBP). Specific surveillance and timely local resection of these benign peripheral nerve sheath tumours might be important to prevent malignant degeneration. In the last years, targeted therapy with MEK inhibitors has shown promise to treat unresectable and symptomatic plexiform neurofibromas. Many more challenges remain to find the best way to monitor children and adults for potential complications and to find a satisfying cure for many complications in this disorder.

The Use of MEK Inhibitors in Neurofibromatosis Type 1-Associated Tumors and Management of Toxicities

Early-phase clinical trials using oral inhibitors of MEK, the mitogen-activated protein kinase kinase, have demonstrated benefit for patients with neurofibromatosis type 1 (NF1)-associated tumors, particularly progressive low-grade gliomas and plexiform neurofibromas. Given this potential of MEK inhibition as an effective medical therapy, the use of targeted agents in the NF1 population is likely to increase substantially. For clinicians with limited experience prescribing MEK inhibitors, concern about managing these treatments may be a barrier to use. In this manuscript, the Clinical Care Advisory Board of the Children's Tumor Foundation reviews the published experience with MEK inhibitors in NF1 and outlines recommendations for side-effect management, as well as monitoring guidelines. These recommendations can serve as a beginning framework for NF providers seeking to provide the most effective treatments for their patients. IMPLICATIONS FOR PRACTICE: Neurofibromatosis type 1 (NF1) clinical care is on the cusp of a transformative shift. With the success of recent clinical trials using MEK inhibitors, an increasing number of NF1 patients are being treated with MEK inhibitors for both plexiform neurofibromas and low-grade gliomas. The use of MEK inhibitors is likely to increase substantially in NF1. Given these changes, the Clinical Care Advisory Board of the Children's Tumor Foundation has identified a need within the NF1 clinical community for guidance for the safe and effective use of MEK inhibitors for NF1-related tumors. This article provides a review of the published experience of MEK inhibitors in NF1 and provides recommendations for monitoring and management of side effects.

Advanced pharmacological therapies for neurofibromatosis type 1-related tumors

Neurofibromatosis Type 1 (NF1) is an autosomal dominant tumor-predisposition disorder that is caused by a heterozygous loss of function variant in the NF1 gene, which encodes a protein called neurofibromin. The absence of neurofibromin causes increased activity in the Rat sarcoma protein (RAS) signalling pathway, which results in an increased growth and cell proliferation. As a result, both oncological and non-oncological comorbidities contribute to a high morbidity and mortality in these patients. Optic pathways gliomas, plexiform neurofibromas and malignant peripheral nerve sheath tumor (MPNST) are the most frequent NF1-associated tumors. The treatment of these complications is often challenging, since surgery may not be feasible due to the location, size, and infiltrative nature of these tumors, and standard chemotherapy or radiotherapy are burdened by significant toxicity and risk for secondary malignancies. For these reasons, following the novel discoveries of the pathophysiological mechanisms that lead to cell proliferation and tumorigenesis in NF1 patients, emerging drugs targeting specific signalling pathways (i.e. the MEK/ERK cascade), have been developed with promising results.

Pediatric Diffuse Midline Gliomas H3 K27M-Mutant and Non-Histone Mutant Midline High-Grade Gliomas in Neurofibromatosis Type 1 in Comparison With Non-Syndromic Children: A Single-Center Pilot Study

Background: Pediatric neurofibromatosis type 1 (NF1) patients rarely develop aggressive central nervous system tumors. Among high-grade gliomas (HGGs), histone mutant diffuse midline gliomas (DMGs H3 K27M-mutant) have exceptionally been reported. The aim of this retrospectives single-center study was to compare the clinical behavior of DMGs H3 K27M-mutant and non-histone mutant midline HGGs in NF1 vs. non-syndromic children and to report imaging features of NF1 HGGs.

Method: We conducted a retrospective review of cerebral DMGs H3 K27M-mutant or non-histone mutant HGGs in 18 patients with or without NF1 followed at our institution between 2010 and 2018. Differences in outcomes, notably progression-free survival (PFS) and overall survival (OS), were evaluated.

Results: Two patients were identified with genetically confirmed diagnosis of NF1 and cerebral HGGs (one DMG H3 K27M-mutant and one histone wild type). Both subjects presented with midline mass lesions with imaging features of aggressive biological activity on advanced MRI or amino-acid PET. During the same time period, 16 non-NF1 patients (11 subjects with DMGs H3 K27M-mutant and 5 with non-histone mutant midline HGGs) were treated at our institution. The two patients with NF1 and HGGs presented a PFS of 3 months and an OS of 5 and 7 months. Median PFS and OS of children without NF1 were respectively 6 and 10 months in DMGs H3 K27M-mutant, and 6 and 11 months in H3 K27M wild-type tumors. Seventy-five percent of subjects with non-NF1 HGGs presented a PFS >4 months compared to 0% in NF1 patients. The 8-month OS of patients with non-NF1 HGGs was 81% compared to 0% in NF1 patients.

Conclusions: Cerebral HGGs arising in midline structures rarely occur in pediatric patients with NF1 and present with extremely poor prognosis, worse than HGGs developing in non-NF1 patients, independent of the presence or absence of H3 K27M mutation. Imaging features of aggressive biological activity on advanced MRI or amino-acid PET imaging suggest prompt neuropathological and molecular investigations.