Optic pathway gliomas in neurofibromatosis-1: controversies and recommendations

Considering Functional Outcomes as Efficacy Endpoints in Pediatric Low-Grade Glioma Clinical Trials: An FDA Educational Symposium

In October 2022, the FDA Oncology Center of Excellence hosted an educational symposium entitled, "Considering Functional Outcomes as Efficacy Endpoints in Pediatric Low-Grade Glioma (pLGG) Clinical Trials." The symposium brought together patient advocates, regulators from the FDA and the European Medicines Agency (EMA), and an international group of academic thought leaders in the field of pediatric neuro-oncology to discuss the potential role of functional outcomes, including visual acuity, motor function, and neurocognitive performance, as endpoints in clinical trials enrolling patients with pLGG. The panel discussed challenges and opportunities regarding the selection, implementation, and evaluation of clinical outcome assessments in these functional domains and outlined key considerations for their inclusion in future clinical trial design and role in new drug development.

Visual Deficits and Diagnostic and Therapeutic Strategies for Neurofibromatosis Type 1: Bridging Science and Patient-Centered Care

Neurofibromatosis type 1 (NF1) is an inherited autosomal dominant disorder primarily affecting children and adolescents characterized by multisystemic clinical manifestations. Mutations in neurofibromin, the protein encoded by the Nf1 tumor suppressor gene, result in dysregulation of the RAS/MAPK pathway leading to uncontrolled cell growth and migration. Neurofibromin is highly expressed in several cell lineages including melanocytes, glial cells, neurons, and Schwann cells. Individuals with NF1 possess a genetic predisposition to central nervous system neoplasms, particularly gliomas affecting the visual pathway, known as optic pathway gliomas (OPGs). While OPGs are typically asymptomatic and benign, they can induce visual impairment in some patients. This review provides insight into the spectrum and visual outcomes of NF1, current diagnostic techniques and therapeutic interventions, and explores the influence of NF1-OPGS on visual abnormalities. We focus on recent advancements in preclinical animal models to elucidate the underlying mechanisms of NF1 pathology and therapies targeting NF1-OPGs. Overall, our review highlights the involvement of retinal ganglion cell dysfunction and degeneration in NF1 disease, and the need for further research to transform scientific laboratory discoveries to improved patient outcomes.

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.

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.

Estrogen-induced glial IL-1β mediates extrinsic retinal ganglion cell vulnerability in murine Nf1 optic glioma

Optic pathway gliomas (OPGs) arising in children with neurofibromatosis type 1 (NF1) can cause retinal ganglion cell (RGC) dysfunction and vision loss, which occurs more frequently in girls. While our previous studies demonstrated that estrogen was partly responsible for this sexually dimorphic visual impairment, herein we elucidate the underlying mechanism. In contrast to their male counterparts, female Nf1OPG mice have increased expression of glial interleukin-1β (IL-1β), which is neurotoxic to RGCs in vitro. Importantly, both IL-1β neutralization and leuprolide-mediated estrogen suppression decrease IL-1β expression and ameliorate RGC dysfunction, providing preclinical proof-of-concept evidence supporting novel neuroprotective strategies for NF1-OPG-induced vision loss.

Pediatric low-grade glioma: State-of-the-art and ongoing challenges

The most common childhood central nervous system (CNS) tumor is pediatric low-grade glioma (pLGG), representing 30%-40% of all CNS tumors in children. Although there is high associated morbidity, tumor-related mortality is relatively rare. pLGG is now conceptualized as a chronic disease, underscoring the importance of functional outcomes and quality-of-life measures. A wealth of data has emerged about these tumors, including a better understanding of their natural history and their molecular drivers, paving the way for the use of targeted inhibitors. While these treatments have heralded tremendous promise, challenges remain about how to best optimize their use, and the long-term toxicities associated with these inhibitors remain unknown. The International Pediatric Low-Grade Glioma Coalition (iPLGGc) is a global group of physicians and scientists with expertise in pLGG focused on addressing key pLGG issues. Here, the iPLGGc provides an overview of the current state-of-the-art in pLGG, including epidemiology, histology, molecular landscape, treatment paradigms, survival outcomes, functional outcomes, imaging response, and ongoing challenges. This paper also serves as an introduction to 3 other pLGG manuscripts on (1) pLGG preclinical models, (2) consensus framework for conducting early-phase clinical trials in pLGG, and (3) pLGG resistance, rebound, and recurrence.

Low-Grade Gliomas: Histological Subtypes, Molecular Mechanisms, and Treatment Strategies

Low-Grade Gliomas (LGGs) represent a diverse group of brain tumors originating from glial cells, characterized by their unique histopathological and molecular features. This article offers a comprehensive exploration of LGGs, shedding light on their subtypes, histological and molecular aspects. By delving into the World Health Organization's grading system, 5th edition, various specificities were added due to an in-depth understanding of emerging laboratory techniques, especially genomic analysis. Moreover, treatment modalities are extensively discussed. The degree of surgical resection should always be considered according to postoperative quality of life and cognitive status. Adjuvant therapies focused on chemotherapy and radiotherapy depend on tumor grading and invasiveness. In the current literature, emerging targeted molecular therapies are well discussed due to their succinctly therapeutic effect; in our article, those therapies are summarized based on posttreatment results and possible adverse effects. This review serves as a valuable resource for clinicians, researchers, and medical professionals aiming to deepen their knowledge on LGGs and enhance patient care.

Optic Pathway Gliomas in Pediatric Population-Current Approach in Diagnosis and Management: Literature Review

In this paper, the authors present a clinical picture of the diagnosis and current treatment regimens of optic pathway glioma in the pediatric population, with an emphasis on the role of an ophthalmic diagnosis in the differentiation and monitoring of lesions. Glioma is the most common optic nerve tumor in children.

MATERIAL

Articles in PubMed, Scholar and Website were reviewed, taking into account current standards of management related to sporadic or NF1-related optic glioma, epidemiology, location, course of the disease, clinical manifestations, histological types of the tumor, genetic predisposition, diagnostic ophthalmic tests currently applicable in therapeutic monitoring of the tumor, neurological diagnosis, therapeutic management and prognosis. The importance of current screening recommendations, in line with standards, was emphasized.

RESULTS

Glioma occurs in children most often in the first decade of life. Initially, they may be asymptomatic, and clinically ophthalmic changes are associated with the organ of vision or with systemic changes. Gliomas associated with the NF1 mutation have a better prognosis for sporadic gliomas. Diagnosis includes radiological imaging methods/MRI/ophthalmology/OCT and visual acuity log MAR assessment. The basis of treatment is clinical observation. In the case of disease progression, surgical treatment, chemotherapy and targeted therapy are used.

CONCLUSION

Further research into novel techniques for detecting gliomas would allow for early monitoring of the disease.

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.

The impact of changes in gadolinium-enhancement on disease progression in children with neurofibromatosis type 1-associated optic pathway glioma: a retrospective analysis

PURPOSE

There has been limited investigation of imaging features associated with visual acuity (VA) decline and initiation of treatment for patients with neurofibromatosis type 1 (NF1) and optic pathway glioma (OPG).

METHODS

To evaluate the association of increased gadolinium enhancement with decline in VA, initiation of chemotherapy, and tumor growth, we performed a retrospective cohort study of children diagnosed with NF1-OPG between January 2006 to June 2016. Two cohorts were defined: a new diagnosis and a longitudinal cohort. Outcomes were examined at 1 and 2 years from initial diagnosis, and 1 and 2 years from initial increase in enhancement in the longitudinal cohort.

RESULTS

Eighty patients were eligible; all 80 contributed to the new diagnosis cohort and 73 to the longitudinal cohort. Fifty-six patients (70%) demonstrated enhancing NF1-OPG at diagnosis. 39% of patients in the new diagnosis cohort and 45% of those in the longitudinal cohort developed increased enhancement during the study period. There was no significant association between increases in enhancement and VA decline in the newly diagnosed or longitudinal cohorts, as well as with initiation of treatment in the longitudinal cohort. Although there was an association of enhancement increase with treatment in the new diagnosis cohort, this association was not maintained when stratified by concurrent change in tumor size.

CONCLUSION

Increased gadolinium-enhancement independent of a concurrent increase in tumor size on MRI should not be used as a marker of NF1-OPG progression and does not appear to be associated with visual decline or initiation of chemotherapy.

A Molecular Update and Review of Current Trials in Paediatric Low-Grade Gliomas

BACKGROUND

Paediatric low-grade gliomas (pLGGs) are the most common primary brain tumour in children. Though considered benign, slow-growing lesions with excellent overall survival, their long-term morbidity can be significant, both from the tumour and secondary to treatment. Vast progress has been made in recent years to better understand the molecular biology underlying pLGGs, with promising implications for new targeted therapeutic strategies.

SUMMARY

A multi-layered classification system of biologic subgroups, integrating distinct molecular and histological features has evolved to further our clinical understanding of these heterogeneous tumours. Though surgery and chemotherapy are the mainstays of treatment for pLGGs, many tumours are not amenable to surgery and/or progress after conventional chemotherapy. Therapies targeting common genetic aberrations in the RAS-mitogen-activated protein kinase (RAS/MAPK) pathway have been the focus of many recent studies and offer new therapeutic possibilities. Here, we summarise the updated molecular classification of pLGGs and provide a review of current treatment strategies, novel agents, and open trials.

KEY MESSAGES

(1) There is a need for treatment strategies in pLGG that provide lasting tumour control and better quality of survival through minimising toxicity and protecting against neurological, cognitive, and endocrine deficits. (2) The latest World Health Organisation classification of pLGG incorporates a growing wealth of molecular genetic information by grouping tumours into more biologically and molecularly defined entities that may enable better risk stratification of patients, and consideration for targeted therapies in the future. (3) Novel agents and molecular-targeted therapies offer new therapeutic possibilities in pLGG and have been the subject of many recent and currently open clinical studies. (4) Adequate molecular characterisation of pLGG is therefore imperative in today's clinical trials, and treatment responses should not only be evaluated radiologically but also using neurological, visual, and quality of life outcomes to truly understand treatment benefits.

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.

Unlocking the power of precision medicine for pediatric low-grade gliomas: molecular characterization for targeted therapies with enhanced safety and efficacy

In the past decade significant advancements have been made in the discovery of targetable lesions in pediatric low-grade gliomas (pLGGs). These tumors account for 30-50% of all pediatric brain tumors with generally a favorable prognosis. The latest 2021 WHO classification of pLGGs places a strong emphasis on molecular characterization for significant implications on prognosis, diagnosis, management, and the potential target treatment. With the technological advances and new applications in molecular diagnostics, the molecular characterization of pLGGs has revealed that tumors that appear similar under a microscope can have different genetic and molecular characteristics. Therefore, the new classification system divides pLGGs into several distinct subtypes based on these characteristics, enabling a more accurate strategy for diagnosis and personalized therapy based on the specific genetic and molecular abnormalities present in each tumor. This approach holds great promise for improving outcomes for patients with pLGGs, highlighting the importance of the recent breakthroughs in the discovery of targetable lesions.

Visual outcomes and predictors in optic pathway glioma: a single centre study

BACKGROUND/AIMS

Optic pathway gliomas (OPGs) may cause progressive visual loss despite chemotherapy. Newer, less toxic treatments might be given earlier, depending on visual prognosis. We aimed to investigate the prognostic value of visual evoked potentials (VEP) and optical coherence tomography (OCT).

METHODS

A retrospective study of OPG patients (treated 2003-2017) was conducted. Primary outcome was PEDIG category visual acuity in better and worse eyes (good < = 0.2, moderate 0.3-0.6 and poor > = 0.7 logMAR). Binary logistic regression analysis was used to identify predictors of these outcomes.

RESULTS

60 patients (32 Neurofibromatosis type 1 [NF1] and 28 sporadic) had median presentation age 49 months (range 17-183) (NF1) and 27 months (range 4-92) (sporadic). Median follow up was 82 months (range 12-189 months). At follow up 24/32 (75%) of NF1 children and 14/28 (50%) of sporadic children had good better eye visual acuity and 11/32 (34%) of NF1 children and 15/28 (54%) of sporadics had poor worse eye acuity. Mean peripapillary retinal nerve fibre layer (RNFL) thickness predicted good better eye final acuity (OR 0.799, 95%CI 0.646-0.987, p = 0.038). Presenting with visual symptoms (OR 0.22 95% CI 0.001-0.508, p = 0.017) and poorer VEP scores (OR 2.35 95% CI 1.1-5.03, p = 0.027) predicted poor worse eye final acuity. 16 children had homonymous hemianopias at follow up, predicted by poor presenting binocular VEP score (OR 1.449 95%CI 1.052-1.995, p = 0.02).

CONCLUSIONS

We found that both RNFL thickness on OCT and VEP were useful in predicting future visual acuity and vision and potentially in planning treatment. We had a high prevalence of homonymous hemianopia.

Kinase Inhibitors in Genetic Diseases

Over the years, several studies have shown that kinase-regulated signaling pathways are involved in the development of rare genetic diseases. The study of the mechanisms underlying the onset of these diseases has opened a possible way for the development of targeted therapies using particular kinase inhibitors. Some of these are currently used to treat other diseases, such as cancer. This review aims to describe the possibilities of using kinase inhibitors in genetic pathologies such as tuberous sclerosis, RASopathies, and ciliopathies, describing the various pathways involved and the possible targets already identified or currently under study.

Comprehensive neurological evaluation of a cohort of patients with neurofibromatosis type 1 from a single institution

Neurofibromatosis type 1 (NF1) is a phenotypically heterogenous multisystem cancer predisposition syndrome manifesting in childhood and adolescents. Central nervous system (CNS) manifestations include structural, neurodevelopmental, and neoplastic disease. We aimed to (1) characterize the spectrum of CNS manifestations of NF1 in a paediatric population, (2) explore radiological features in the CNS by image analyses, and (3) correlate genotype with phenotypic expression for those with a genetic diagnosis. We performed a database search in the hospital information system covering the period between January 2017 and December 2020. We evaluated the phenotype by retrospective chart review and imaging analysis. 59 patients were diagnosed with NF1 [median age 10.6 years (range, 1.1-22.6); 31 female] at last follow-up, pathogenic NF1 variants were identified in 26/29. 49/59 patients presented with neurological manifestations including 28 with structural and neurodevelopmental findings, 16 with neurodevelopmental, and 5 with structural findings only. Focal areas of signal intensity (FASI) were identified in 29/39, cerebrovascular anomalies in 4/39. Neurodevelopmental delay was reported in 27/59 patients, learning difficulties in 19/59. Optic pathway gliomas (OPG) were diagnosed in 18/59 patients, 13/59 had low-grade gliomas outside the visual pathways. 12 patients received chemotherapy. Beside the established NF1 microdeletion, neither genotype nor FASI were associated with the neurological phenotype. NF1 was associated with a spectrum of CNS manifestations in at least 83.0% of patients. Regular neuropsychological assessment complementing frequent clinical and ophthalmologic testing for OPG is necessary in the care of each child with NF1.

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.

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).

The role of visual electrodiagnostics in management of children with neurofibromatosis type 1

PURPOSE

To evaluate the role of visual electrodiagnostic testing in children with neurofibromatosis type 1 (NF1) despite improved accessibility to magnetic resonance imaging (MRI).

METHODS

The records from 39 children (78 eyes, 15 boys, 24 girls, average age at last visit of 11.5 ± 4.3 years, average follow-up time of 7.8 ± 3.9 years) with genetically confirmed NF1 were retrospectively analysed. They all underwent a thorough ophthalmological investigation, including age-appropriate visual acuity testing, anterior segment evaluation for Lisch nodules and a dilated fundus examination. If children were cooperative enough, colour vision was tested using the Hardy-Rand-Rittler test, visual fields were evaluated with Goldmann perimetry. All performed MRI of the brain and orbits as part of the standard of care protocol. Visual electrodiagnostics included electroretinography (ERG) and visual evoked potentials (VEP) using a standard protocol in older children, whereas with less cooperative children a modified protocol according to the Great Ormond Street Hospital (GOSH protocol) was used.

RESULTS

The average visual acuity was 0.8 ± 0.3, colour vision was abnormal in 6%, perimetry in 8%, Lisch nodules were present in 62%, and the optic disc was pale in 66% of all eyes. Plexiform neurofibroma of the eyelid/orbit was present in 4%. Optic pathway glioma (OPG) was detected with MRI in 22 (57%) and in 6/22 treatment was indicated. Other intracranial NF1-related lesions were documented in 70% of children. VEP were abnormal in 16/39 of all children with NF1 (41%) comprising 14/22 (65%) of children with confirmed OPG and 2/17 (12%) of children without OPG. All full-field and pattern ERG responses were within normal limits. All individual VEP results are described and three cases from this cohort of children are presented in detail to illustrate the importance of VEP testing. In Case 1, VEP abnormality suggested subsequent MRI of the brain under general anaesthesia, which was otherwise contraindicated according to normal clinical findings and his young age. In Cases 2 and 3, VEP provided more precise functional information during the follow-up of OPG, while other psychophysical tests remained unchanged.

CONCLUSIONS

Electrodiagnostics has multifactorial role and importance in children with NF1, either when visual pathway function is impaired in young children, even before MRI under general anaesthesia and other psychophysical tests can be performed, as well as for a more precise monitoring of the visual pathway function before potential treatment of OPG, or after it, to evaluate its success.

BRAF-mediated brain tumors in adults and children: A review and the Australian and New Zealand experience

The mitogen-activated protein kinase (MAPK) pathway signaling pathway is one of the most commonly mutated pathways in human cancers. In particular, BRAF alterations result in constitutive activation of the rapidly accelerating fibrosarcoma-extracellular signal-regulated kinase-MAPK significant pathway, leading to cellular proliferation, survival, and dedifferentiation. The role of BRAF mutations in oncogenesis and tumorigenesis has spurred the development of targeted agents, which have been successful in treating many adult cancers. Despite advances in other cancer types, the morbidity and survival outcomes of patients with glioma have remained relatively stagnant. Recently, there has been recognition that MAPK dysregulation is almost universally present in paediatric and adult gliomas. These findings, accompanying broad molecular characterization of gliomas, has aided prognostication and offered opportunities for clinical trials testing targeted agents. The use of targeted therapies in this disease represents a paradigm shift, although the biochemical complexities has resulted in unexpected challenges in the development of effective BRAF inhibitors. Despite these challenges, there are promising data to support the use of BRAF inhibitors alone and in combination with MEK inhibitors for patients with both low-grade and high-grade glioma across age groups. Safety and efficacy data demonstrate that many of the toxicities of these targeted agents are tolerable while offering objective responses. Newer clinical trials will examine the use of these therapies in the upfront setting. Appropriate duration of therapy and durability of response remains unclear in the glioma patient cohort. Longitudinal efficacy and toxicity data are needed. Furthermore, access to these medications remains challenging outside of clinical trials in Australia and New Zealand. Compassionate access is limited, and advocacy for mechanism of action-based drug approval is ongoing.

Optic Pathway Gliomas: The Trends of Basic Research to Reduce the Impact of the Disease on Visual Function

Pediatric optic pathway gliomas (OPG) are low-grade brain tumors characterized by slow progression and invalidating visual loss. Common therapeutic strategies include surgery, radiotherapy, chemotherapy, and combinations of these modalities, but despite the different treatment strategies, no actual treatment exists to prevent or revert visual impairment. Nowadays, several reports of the literature show promising results regarding NGF eye drop instillation and improvement of visual outcome. Such results seem to be related with the NGF-linked prevention in caspase activation, which reduces retinal ganglion cell loss.Reducing retinal ganglion cell loss results clinically in visual field improvement as well as visual electric potential and optical coherence tomography gain. Nonetheless, visual acuity fails to show significant changes.Visual impairment represents nowadays one of the major issues in dealing with OPGs. Secondary to the interesting results offered by NGF eye drop administration, further studies are warranted to better comprehend potential treatment strategies.

Role of nerves in neurofibromatosis type 1-related nervous system tumors

BACKGROUND

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder that affects nearly 1 in 3000 infants. Neurofibromin inactivation and NF1 gene mutations are involved in various aspects of neuronal function regulation, including neuronal development induction, electrophysiological activity elevation, growth factor expression, and neurotransmitter release. NF1 patients often exhibit a predisposition to tumor development, especially in the nervous system, resulting in the frequent occurrence of peripheral nerve sheath tumors and gliomas. Recent evidence suggests that nerves play a role in the development of multiple tumor types, prompting researchers to investigate the nerve as a vital component in and regulator of the initiation and progression of NF1-related nervous system tumors.

CONCLUSION

In this review, we summarize existing evidence about the specific effects of NF1 mutation on neurons and emerging research on the role of nerves in neurological tumor development, promising a new set of selective and targeted therapies for NF1-related tumors.

[Neurofibromatosis type 1 : From diagnosis to follow-up]

BACKGROUND

Neurofibromatosis type 1 (NF1) is a tumor predisposition syndrome and is one of the most common genetic diseases. It is therefore a condition encountered by radiologists in clinical routine. Since the variability of the clinical expression is very high and several organ systems are affected, we present a standardized diagnostic approach in this article.

METHODS

Evaluation of the literature on neurofibromatosis type 1 in the context of radiological examination methods.

RESULTS

In addition to the frequently known changes in the central and peripheral nervous system such as optic gliomas and plexiform neurofibromas, lesions from the orthopedic spectrum and vascular changes must also be included in the radiological diagnosis.

CONCLUSIONS

Due to the diversity of the clinical picture of NF1, it is reasonable to define an examination strategy which takes into account the needs of radiological routine and also reliably detects the most frequent and prognostically significant pathologies accompanying this disease. In this article, the current recommendations for diagnosis of neurofibromatosis-associated tumors and skeletal changes are summarized, and examination protocols and time intervals are suggested.

Gliomas of the Optic Nerve: A SEER-Based Epidemiologic Study

BACKGROUND

To determine whether patients with biopsy-confirmed optic nerve glioma differ in clinical features and outcomes from those diagnosed by neuroradiologic imaging alone.

METHODS

Retrospective comparative analysis. Pilocytic astrocytomas (PAs) and gliomas of the optic nerve were identified through ICD-O codes in the Surveillance, Epidemiology, and End Results (SEER) cancer registry from 1975 through 2017. Demographics, clinical features, and outcomes were compared according to the method of diagnosis (biopsy-confirmed and radiologic only) and by age (birth through 19 years and 20 years of age and older). Differences in proportions were tested with the chi-square test. Associations with tumor-related death were evaluated with logistic regression. Statistical significance: α < 0.01.

RESULTS

Over 42 years, 313 PAs and 720 gliomas of the optic nerve were identified. The young age distributions were similar between the 2 groups. PAs were biopsied more often than gliomas (54% vs 13.2% [ P < 0.001]). Tumor-attributable death occurred more often among PAs and gliomas that were biopsied than those that were not (7.1% vs 0.7% [ P < 0.01]; 7.4% vs 1.1% [ P < 0.01], respectively). Roughly 15% of both PAs and gliomas were diagnosed in persons 20 years and older.

CONCLUSIONS

Biopsy-confirmed cases of PA and glioma of the optic nerve were associated with more therapeutic interventions and worse outcomes compared with patients who were diagnosed radiologically. Clinical variables relevant to clinical decision-making not captured by SEER likely explain the inability to meaningfully interpret outcome from the registry database. Cancer registries should avoid coding specific histopathologic diagnoses when tissue is not obtained.

Nervous system (NS) Tumors in Cancer Predisposition Syndromes

Genetic syndromes which develop one or more nervous system (NS) tumors as one of the manifestations can be grouped under the umbrella term of NS tumor predisposition syndromes. Understanding the underlying pathological pathways at the molecular level has led us to many radical discoveries, in understanding the mechanisms of tumorigenesis, tumor progression, interactions with the tumor microenvironment, and development of targeted therapies. Currently, at least 7-10% of all pediatric cancers are now recognized to occur in the setting of genetic predisposition to cancer or cancer predisposition syndromes. Specifically, the cancer predisposition rate in pediatric patients with NS tumors has been reported to be as high as 15%, though it can approach 50% in certain tumor types (i.e., choroid plexus carcinoma associated with Li Fraumeni Syndrome). Cancer predisposition syndromes are caused by pathogenic variation in genes that primarily function as tumor suppressors and proto-oncogenes. These variants are found in the germline or constitutional DNA. Mosaicism, however, can affect only certain tissues, resulting in varied manifestations. Increased understanding of the genetic underpinnings of cancer predisposition syndromes and the ability of clinical laboratories to offer molecular genetic testing allows for improvement in the identification of these patients. The identification of a cancer predisposition syndrome in a CNS tumor patient allows for changes to medical management to be made, including the initiation of cancer surveillance protocols. Finally, the identification of at-risk biologic relatives becomes feasible through cascade (genetic) testing. These fundamental discoveries have also broadened the horizon of novel therapeutic possibilities and have helped to be better predictors of prognosis and survival. The treatment paradigm of specific NS tumors may also vary based on the patient's cancer predisposition syndrome and may be used to guide therapy (i.e., immune checkpoint inhibitors in constitutional mismatch repair deficiency [CMMRD] predisposition syndrome) [8]. Early diagnosis of these cancer predisposition syndromes is therefore critical, in both unaffected and affected patients. Genetic counselors are uniquely trained master's level healthcare providers with a focus on the identification of hereditary disorders, including hereditary cancer, or cancer predisposition syndromes. Genetic counseling, defined as "the process of helping people understand and adapt to the medical, psychological and familial implications of genetic contributions to disease" plays a vital role in the adaptation to a genetic diagnosis and the overall management of these diseases. Cancer predisposition syndromes that increase risks for NS tumor development in childhood include classic neurocutaneous disorders like neurofibromatosis type 1 and type 2 (NF1, NF2) and tuberous sclerosis complex (TSC) type 1 and 2 (TSC1, TSC2). Li Fraumeni Syndrome, Constitutional Mismatch Repair Deficiency, Gorlin syndrome (Nevoid Basal Cell Carcinoma), Rhabdoid Tumor Predisposition syndrome, and Von Hippel-Lindau disease. Ataxia Telangiectasia will also be discussed given the profound neurological manifestations of this syndrome. In addition, there are other cancer predisposition syndromes like Cowden/PTEN Hamartoma Tumor Syndrome, DICER1 syndrome, among many others which also increase the risk of NS neoplasia and are briefly described. Herein, we discuss the NS tumor spectrum seen in the abovementioned cancer predisposition syndromes as with their respective germline genetic abnormalities and recommended surveillance guidelines when applicable. We conclude with a discussion of the importance and rationale for genetic counseling in these patients and their families.

The Utility of Early Brain MRI for Patients with Neurofibromatosis Type 1 and Optic Pathway Glioma: A Long-Term Follow-Up in a Tertiary Referral Hospital

Screening studies have shown detection of optic pathway gliomas (OPGs) in 8 to 31% of children with neurofibromatosis type 1 (NF1). Many of those affected show prolonged indolent phases, but others develop vision disturbances even before diagnosis and treatment. We assessed the clinical presentation at diagnosis, location, natural progression, and risk factors for impaired vision of OPG. The clinical database of the NF1 multidisciplinary clinic of Schneider Children's Medical Center of Israel was reviewed for all patients diagnosed and followed with NF1 during 2007 to 2019. OPG was diagnosed by hyperintensity and thickening along the optic pathway on T2-weighted brain magnetic resonance imaging (MRI), with or without contrast enhancement. Of 257 children with NF1 who underwent MRI, 57 (22%) were diagnosed with OPG; 31 (54%) were females. Twenty-five (44%) had familial NF1. Fifteen (26%) who exhibited tumor progression and worsening in ophthalmic examinations required treatment. Post-chiasmatic glioma was a predictive factor for treatment (p < 0.05), whereas MRI done later and female gender were not significant. Four patients who eventually needed therapy had normal ophthalmic examinations at least 1 year prior to their first MRI. For 6 (40%) of the patients treated, vision continued to worsen. Our findings demonstrate that normal ophthalmic examinations do not always exclude OPG in children with NF1. Early brain MRI before age 36 months may detect OPG, lead to better follow-up and early treatment, and help improve vision outcome.

Management of Optic Pathway Glioma: A Systematic Review and Meta-Analysis

Background: OPG accounts for 3−5% of childhood central nervous system (CNS) tumors and about 2% of pediatric glial lesions. Methods: Article selection was performed by searching PubMed, Web of Science, and Cochrane databases. Results: The pooled mortality rate was 0.12 (95%CI 0.09−0.14). Due to the unrepresentative data, improved and not changed outcomes were classified as favorable outcomes and worsened as unfavorable. Meta-analyses were performed to determine the rate of clinical and radiological favorable outcomes. In terms of visual assessment, the pooled rate of a favorable outcome in chemotherapy, radiotherapy, and surgery was 0.74, 0.81, and 0.65, respectively, and the overall pooled rate of the favorable outcome was 0.75 (95%CI 0.70−0.80). In terms of radiological assessment, the rate of a favorable outcome following chemotherapy, radiotherapy, and surgery was 0.71, 0.74, and 0.67, respectively, and the overall pooled rate of the favorable outcome is 0.71 (95%CI 0.65−0.77). The subgroup analysis revealed no significant difference in the rate of clinical and radiological favorable outcomes between the different treatment modalities (p > 0.05). Conclusion: Our analyses showed that each therapeutic modality represents viable treatment options to achieve remission for these patients.

Pilocytic astrocytoma of the cerebellopontine angle: a rare case

Background

Pilocytic astrocytomas are the most common primary brain tumors in children. Most of the lesions occur in or near the midline. They are rare in extra-axial locations.

Case presentation

We report a 23-year-old lady who was found to have progressive right-sided sensorineural hearing loss and features of raised intracranial pressure due to a pilocytic astrocytoma of the right cerebellopontine angle. After an extensive Medline search, we could find only three cases of primary extra-axial pilocytic astrocytoma of the cerebellopontine angle (CPA) reported till now.

Conclusion

Even a rare occurrence, primary pilocytic astrocytoma, and in general gliomas, should be kept in mind in the differential diagnosis of CPA lesions.

Current update on the visual outcome of optic pathway glioma associated with neurofibromatosis type-1

Purpose

Clinical and diagnostic evaluation in the follow-up of optic glioma patients with neurofibromatosis type 1 (NF-1) can be difficult. Determining whether and when to provide treatment is a significant challenge in best managing these patients. Update on current information and future directions in management is included in this review.

Current Practice

NF-associated optic pathway gliomas (OPGs) present a significant management challenge with high stakes for visual outcomes. Monitoring vision and diagnostic tests are challenging in patients of a younger age. Regardless of whether few or many optic gliomas are encountered during clinical practice.

Summary

This review of optic gliomas-NF1-associated gliomas includes the current approach and knowledge of OPG-NF1 and future directions in OPG-NF1 management. This includes the ongoing Multicenter Natural History Study and other clinical trials and outcomes in NF-1 patients with OPG.

A rare MRI finding of NF-1: perineural arachnoidal gliomatosis

Optic pathway gliomas are the most common central nervous system neoplasms in patients with neurofibromatosis type 1. Perineural arachnoidal gliomatosis is a rare and distinctive growth pattern of optic nerve glioma, in which the tumor infiltrates through the pia mater and pre-dominantly involves the subarachnoid space around the optic nerve. Here, we report an 8-year-old girl with perineural arachnoidal gliomatosis associated with neurofibromatosis type 1.

Predictors of Patient Return to a Tertiary Neurofibromatosis Subspecialty Clinic

OBJECTIVE

To evaluate sociodemographic and medical predictors of patient return to a neurofibromatosis subspecialty clinic.

STUDY DESIGN

Data were collected from the Washington University Neurofibromatosis Clinical Program electronic medical records. A total of 713 subjects with initial visits to the Washington University Neurofibromatosis Clinical Program between July 1, 2005 and December 18, 2020 were included. Variables collected included sex, race, ethnicity, age, date of first visit, place of residence, diagnosis, insurance payer, physician recommendation for return, and subject return. Return rates for each demographic group were calculated. Bivariate analyses were performed to inform variable inclusion in the model, and a binary logistic regression model was calculated to predict subject return.

RESULTS

The overall return rate was 76%. The binary logistic regression model was statistically significant (χ²₉ = 131.094; P < .001) and showed that subjects who self-identified as Black and/or African American, presented with or received a diagnosis of café-au-lait macules at their initial visit, were from a rural area, were older, or who lived farther from the Washington University Neurofibromatosis Clinical Program were less likely to return to clinic.

CONCLUSIONS

These findings support the implementation of tailored communication and monitoring interventions to improve the care for children with neurofibromatosis type 1.

Visual Outcome for Children with Optic Pathway Gliomas Treated with Systemic Chemotherapy

Purpose

Patients and Methods

Results

Conclusion

Optical Coherence Tomography Significance in Managing Early Onset of Optic Pathway Gliomas in Children Younger than 5 Years of Age—A Retrospective Study

We aimed to investigate the significance of optical coherence tomography (SD-OCT) in managing pediatric optic pathway gliomas (OPGs) in children younger than 5 years of age. A retrospective monocentric study was conducted. SD-OCT scans were obtained using the handheld iVue system to assess peripapillary retinal nerve fibre layer (pRNFL) thickness at three time points: baseline (OCT1), end of treatment (OCT2), and at last follow-up (OCT3). We compared the median value of pRNFL (and interquartile range—IQR) at different follow-up times and in different sub-groups (stable disease—SD, partial response—PR, and progression disease—PD). Thirteen children younger than 5 years of age were included. The Median follow-up time was 3.9 years (IQR 1.2). Six patients showed a pRNFL change of more than 10% during follow-up. Seven patients showed PD during follow-up. Median pRNFL at baseline was 81.5 µm (IQR 31.5); median pRNFL at the end of treatment was 73 µm (IQR 33); median pRNFL at last follow-up was 72 µm (IQR 38.5). The mean pRNFL at baseline was significantly lower than the mean normative values. Only subjects with PD showed pRNFL change close to statistical significance. This study confirms the role of SD-OCT in managing OPGs for therapeutic decisions and strategy planning of visual rehabilitation.

Bibliometric analysis of the top 100 most-cited articles in neurofibromatosis

Background:

Neurofibromatosis (NF) is an umbrella term that refers to three distinct disease entities: NF Type 1, Type 2, and schwannomatosis. Here, we reviewed the scientific performance and the most influential publications on NF.

Methods:

A keyword-based search was performed using the Scopus database. The top 100 articles were grouped based on NF types and the studied entities. The differences between the articles, authors, and journals were quantified based on certain parameters. Other parameters were collected for the complete citational analysis.

Results:

The top 100 articles were published between 1961 and 2020. The most trending period of research was in the 1990s and articles studying the clinical aspect and the underlying genetic correlation made up 84% of all articles from the list. The United States of America (USA) had the highest number of contributions (69 articles, 69%). The top institute of contribution to the list was the Howard Hughes Medical Institute, USA (14 articles, 14%). Author-based analysis reveals that the neurologist D. H. Gutmann from St. Louis Children’s Hospital, USA, was the most active and authored 11 articles (11%) on the list.

Conclusion:

The publication trends show that articles studying medical and surgical management were of little interest. The top 100 articles did not include any randomized control trials, and the highest level of evidence was obtained from reviews of pooled knowledge as well as population-based and longitudinal studies.

Neurofibromatosis from Head to Toe: What the Radiologist Needs to Know

Neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2) are autosomal dominant inherited neurocutaneous disorders or phakomatoses secondary to mutations in the NF1 and NF2 tumor suppressor genes, respectively. Although they share a common name, NF1 and NF2 are distinct disorders with a wide range of multisystem manifestations that include benign and malignant tumors. Imaging plays an essential role in diagnosis, surveillance, and management of individuals with NF1 and NF2. Therefore, it is crucial for radiologists to be familiar with the imaging features of NF1 and NF2 to allow prompt diagnosis and appropriate management. Key manifestations of NF1 include café-au-lait macules, axillary or inguinal freckling, neurofibromas or plexiform neurofibromas, optic pathway gliomas, Lisch nodules, and osseous lesions such as sphenoid dysplasia, all of which are considered diagnostic features of NF1. Other manifestations include focal areas of signal intensity in the brain, low-grade gliomas, interstitial lung disease, various abdominopelvic neoplasms, scoliosis, and vascular dysplasia. The various NF1-associated abdominopelvic neoplasms can be categorized by their cellular origin: neurogenic neoplasms, interstitial cells of Cajal neoplasms, neuroendocrine neoplasms, and embryonal neoplasms. Malignant peripheral nerve sheath tumors and intracranial tumors are the leading contributors to mortality in NF1. Classic manifestations of NF2 include schwannomas, meningiomas, and ependymomas. However, NF2 may have shared cutaneous manifestations with NF1. Lifelong multidisciplinary management is critical for patients with either disease. The authors highlight the genetics and molecular pathogenesis, clinical and pathologic features, imaging manifestations, and multidisciplinary management and surveillance of NF1 and NF2. Online supplemental material is available for this article. ^©RSNA, 2022.

Rethinking the Management of Optic Pathway Gliomas: A Single Center Experience

Background

Optic pathway gliomas (OPGs) are rare neoplasms in children with an unpredictable clinical course. Approximately 15% of OPGs occur in patients affected by neurofibromatosis type 1 (NF1): the clinical course of these cases is more indolently than sporadic ones, and NF1 patients less frequently require treatment including surgery. Instead, over 90% of sporadic OPGs require one or more therapeutic approaches. The management of OPG is controversial. They are also characterized by a high risk of morbidity including hypothalamic damage, endocrine deficits, visual deficit and/or neurological impairment.

Materials and Methods

In this paper, we evaluated visual and endocrinological outcomes of a population of OPG followed at our center from 2013 to 2021, with a particular emphasis on the role of surgery.

Results

Twenty-six patients were included in this study (mean age of 40.7 months). Tumor location on imaging was described by the Dodge classification. Five cases had NF 1. Thirteen cases received biopsy and 13 were partially resected. Histopathology revealed 19 cases of pilocytic astrocytomas, 2 pilomyxoid astrocytoma and 5 ganglioglioma. All the patients required a post-surgical adjuvant treatment according to current indications for low-grade gliomas. Molecular studies (BRAF status and mTOR/pmTOR pathway) have been performed in 24/26 patients, following for the use of target therapy in 11 of these patients. In our study we found that patients underwent biopsy have a better visual and endocrinological outcomes rather than patients with a tumor debulking. The five-year overall survival rate is 98% with a mean follow-up of 60 months.

Conclusions

Many children with OPGs survive with a residual tumor. They suffer from chronic diseases such as endocrine dysfunction, visual disturbance, motor deficits and poor quality of life. All patients need comprehensive diagnostic work-up including neuroimaging, clinical evaluations and neuropathology approach; at the same time, they need therapeutic decisions and concepts for the choice of timing and type of neurosurgical intervention, chemotherapy and target therapy as well as surveillance and rehabilitation to maximize survival and overall functional outcomes. Our study showed that minimal invasive surgery with the purpose of molecular characterization of the tumor is desirable to reduce morbidity correlate to surgery.

Epidemiological profile and clinical characteristics of 491 Brazilian patients with neurofibromatosis type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a chronic and progressive autosomal dominant genetic and sporadic disease characterized by cutaneous and neurological abnormalities. Plexiform neurofibroma (PN), a significant cause of clinical complications in NF-1, is a benign tumor of the peripheral nerve sheath that involves multiple nerve fascicles. Although there is an important number of patients who are affected by NF1 in Brazil, there is little data on the behavior of the disease in the national literature as well as in other low- and middle-income countries.

METHODS

We performed a retrospective analysis of 491 patients with NF1 followed at two reference centers in Brazil.

RESULTS

Approximately 38% of patients had PNs, resulting in reduced life quality. The median patient age with PNs was 30 years (range: 6 to 83 years). Head and neck, and extremity were the main affected locations with 35.8 and 30.6%, respectively. PNs were classified as asymptomatic in 25.1% of patients, while 52.5% presented symptomatic and inoperable tumors. The most common manifestations related to PNs were disfigurement and orthopedic involvement. Twenty patients developed neoplasms and ten (50%) presented with malignant peripheral nerve sheath tumors (MPNST). The prevalence of MPNST in our study was 2.9%.

CONCLUSIONS

Patients with NF1 experience clinically significant morbidity, especially when it is associated with PN. Though there are many patients affected by NF1 in Brazil and other low- and middle-income countries, there is little data available in the corresponding literature. Our results are comparable to the previous results reported from higher-income countries and international registries.

Supratentorial Pediatric Midline Tumors and Tumor-like Lesions: Clinical Spectrum, Natural History and Treatment Options

Childhood Central Nervous System tumors account for 25% of all pediatric tumors. Large availability and broadening of indications to imaging has made incidental findings more common. Among these, midline lesions have different clinical relevance depending on their intrinsic pattern of behaviour and on their specific location. In this narrative review we describe the natural history and treatment options of midline lesions in children.

Evaluating the Evidence: Scientometric Analysis of Highly Cited Neurofibromatosis 1 Publications

The study of Neurofibromatosis 1 (NF1) is progressing rapidly. This study aimed to identify historical trends in publications focusing on NF1, to find the top 100 most cited publications on this topic, and to evaluate their level of evidence. This study identifies historical trends in publication regarding NF1 with the aim of providing readers useful information about the areas of research being performed, an educational guide to facilitate novice researchers in conducting effective evidence-based medical research, and unique insight into developments and trends of NF 1 research. This study also evaluates the evidence of highly cited papers on NF1.

A search of all databases and journals accessible within Elsevier's Scopus was performed on June 27th, 2020, using combinations of the Boolean queries "Neurofibromatosis 1," "Von Recklinghausen," and "NF1," which yielded 13,599 documents. The top 100 most-cited papers were identified, analyzed, and evaluated for level of evidence. Evidence was assessed using the GRADE guidelines.

The top 100 most-cited articles span years 1963-2010 and are published in 50 different journals. The average number of citations per publication was 366.5 (range 189-1527). The most cited article is "Neurofibromatosis: Conference Statement" (Stumpf et al., 1988). In this study, the top 100 most-cited works in NF1 are identified, characterized, and analyzed. This study will serve as a historical point of reference for future research, a jumping point for those unfamiliar with the topic, and an educational foundation for future NF1 specialists and researchers.

Choroidal Abnormalities in Pediatric NF1: A Cohort Natural History Study

The purpose of this study was to assess the long-term natural history of choroidal abnormalities (CAs) in a large pediatric neurofibromatosis type 1 (NF1) population, quantifying their progression in number and dimensions. Pediatric patients (<16 years old) affected by NF1 with a minimum follow-up of 3 years with at least one CA in one eye were consecutively recruited. Near-infrared (NIR) imaging was performed to identify CAs, which were quantified in number and size. The CAs area and perimeter were normalized for the optic disc dimensions to avoid possible bias related to the growing process of the eye. Ninety-nine eyes of 53 patients were evaluated. The CAs number, area and perimeter significantly increased during follow-up (p < 0.0001 for each parameter). The patient age at baseline was inversely correlated with the CAs number over time (coefficient = −0.1313, p = 0.0068), while no correlation was found between the patient age and CAs progression in size. In conclusion, we provide evidence that, in NF1 pediatric patients, CAs change over time, increasing both in number and dimensions, independently from the physiological growth of the eye. While the increase of the CAs number occurs particularly at an earlier age, the increase in the CAs dimensions is a slow process that remains constant during childhood.

Visual Outcomes of Optic Pathway Glioma Treated With Chemotherapy in Neurofibromatosis Type 1

PURPOSE

To analyze the visual outcomes following chemotherapy for optic pathway glioma in children with neurofibromatosis type 1.

METHODS

This was a retrospective cohort study of 58 children with optic pathway glioma between 2003 and 2019. Best corrected visual acuity (BCVA) at diagnosis and at the last follow-up visit were analyzed. Correlation tests were performed to determine whether the final BCVA was predicted by the initial BCVA, initial Dodge stage, or retinal nerve fiber layer (RNFL) thickness stability. The first-line chemotherapy regimen included vincristine plus carboplatin (2003 to 2016) and vinblastine (since 2017).

RESULTS

Twenty-four children (41%) received chemotherapy. The median age at diagnosis was 3 years, and 61% of the children were female. From the first visit to the last follow-up visit, there was a statistically significant difference in mean BCVA in eyes in the no treatment group (P = .034) but not in eyes in the chemotherapy group (P = .824). A moderate and weak positive correlation was found (r = 0.58 and r = 0.29, respectively). At the last follow-up visit, BCVA remained stable in 73% and improved in 27% of eyes in the no treatment group, and BCVA worsened in 25%, remained stable in 62%, and improved in 13% of eyes in the chemotherapy group. At the last follow-up visit, BCVA and Dodge stage had a weak negative correlation (r = -0.06 and r = -0.17, respectively). A negative moderate correlation was identified between RNFL thickness and BCVA at the last follow-up visit (r = -0.48 in the no treatment group and r = -0.46 in the chemotherapy group).

CONCLUSIONS

Children treated with chemotherapy had worse BCVA, although the treatment arrested the decline or improved BCVA in 75% of the patients with no major side effects. [J Pediatr Ophthalmol Strabismus. 2022;59(2):128-135.].

Novel "T-Dimension" Therapies for Pediatric Optic Pathway Glioma: A Timely, Targeted, and Tailored Treatment Trend

INTRODUCTION

Novel targeted and tailored therapies can substantially improve the prognosis for optic pathway glioma (OPG), especially when implemented in a timely manner. However, their tremendous potential remains underestimated. Therefore, in this study, we provide an updated overview of the clinical trials, current trends, and future perspectives for OPG's novel therapeutic strategies.

METHODS

We completed an extensive literature review using the PubMed, MEDLINE, and ClinicalTrials.gov databases. We analyzed and reported the data following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Thioguanine, procarbazine, lomustine, and vincristine/vinblastine, as well as cisplatin-etoposide, provided excellent results in advanced-phase trials. Selumetinib and trametinib, two oral MEK inhibitors, have been approved for recurrent or refractory OPGs in association with the angiogenetic inhibitor bevacizumab. Among the mTOR inhibitors, everolimus and sirolimus showed the best results. Stereotactic radiosurgery and proton beam radiation therapy have advantages over conventional radiotherapy regimens. Timely treatment is imperative for acute visual symptoms with evidence of tumor progression. This latest evidence can help define a novel "T-Dimension" for pediatric OPG therapies.

CONCLUSION

The novel "T-Dimension" for pediatric OPGs is based on recent evidence-based treatments, including combination chemotherapy regimens, molecular targeted therapies, stereotactic radiosurgery, and proton beam radiation therapy. Additional clinical trials are essential for validating each of these new therapies.

[Prognostic factors of neurofibromatosis type 1-associated optic pathway gliomas in children]

INTRODUCTION

Optic pathway glioma (OPG) is a classic complication of neurofibromatosis type 1 (NF1) and can impair visual function in children with this condition. The objective of this study is to describe clinical, paraclinical and prognostic characteristics of OPG associated with NF1.

MATERIALS AND METHODS

In this retrospective observational study of children followed for OPG associated with NF1 in a University Hospital, we analyzed the ophthalmological examination, brain and orbital imaging, management and the presence of associated endocrinopathy.

RESULTS

We examined 114 children with NF1, of which 26 (22.81%) presented with OPG. Mean ages at diagnosis of NF1 and OPG were 3.83 years and 6.23 years, respectively. Mean visual acuity was 20/24.4 for the worse eye and 20/23.1 for the better eye. The RNFL (retinal nerve fiber layer) was thinner in subjects than in age-matched controls (p <0.0001). Retrochiasmal location of the OPG (DodgeC) was associated with lower binocular visual acuity than other locations and <20/32 (p=0.028); 28.03% of OPG (5 girls and 1 boy) were treated with chemotherapy, and the others were monitored; 19.23% had an associated endocrinopathy.

CONCLUSIONS

OPG complicates 22.81% of NF1 cases in our series. Our study shows that retrochiasmal location of the glioma and female sex are poor prognostic factors. It also highlights the important role of OCT, since a decrease in RNFL is statistically associated with the presence of an OPG.

Challenges in the diagnosis of neurofibromatosis type 1 (NF1) in young children facilitated by means of revised diagnostic criteria including genetic testing for pathogenic NF1 gene variants

Neurofibromatosis type 1 (NF1) is the most frequent disorder associated with multiple café-au-lait macules (CALM) which may either be present at birth or appear during the first year of life. Other NF1-associated features such as skin-fold freckling and Lisch nodules occur later during childhood whereas dermal neurofibromas are rare in young children and usually only arise during early adulthood. The NIH clinical diagnostic criteria for NF1, established in 1988, include the most common NF1-associated features. Since many of these features are age-dependent, arriving at a definitive diagnosis of NF1 by employing these criteria may not be possible in infancy if CALM are the only clinical feature evident. Indeed, approximately 46% of patients who are diagnosed with NF1 later in life do not meet the NIH diagnostic criteria by the age of 1 year. Further, the 1988 diagnostic criteria for NF1 are not specific enough to distinguish NF1 from other related disorders such as Legius syndrome. In this review, we outline the challenges faced in diagnosing NF1 in young children, and evaluate the utility of the recently revised (2021) diagnostic criteria for NF1, which include the presence of pathogenic variants in the NF1 gene and choroidal anomalies, for achieving an early and accurate diagnosis.

Glioma-Induced Seizure in a Neurofibromatosis Type 1 Patient: A Case Report

Neurofibromatosis type 1 (NF-1), also known as Von Recklinghausen's disease, is an autosomal-dominant disease that is characterized by high-frequency mutations leading to multiple benign tumors called neurofibromas and café au lait spots on the skin. Although NF-1 mainly affects the nervous system, it can have multisystem involvement as well, associated with the cardiovascular, orthopedic, gastrointestinal, and dermatologic systems. Psychiatric complications like anxiety, dysthymia, and depression have also been reported in patients with NF-1. The prevalence of this disorder is one in 3,000 births. NF-1 patients have a higher prevalence of seizures compared to the general population.

A 20-year-old male with a diagnosis of NF-1 at the age of three months presented to the emergency room (ER) of a local hospital for the evaluation of an unwitnessed seizure characterized by loss of consciousness and bladder control. MRI of the brain without contrast revealed hyperintensities in the mesial temporal lobe bilaterally, with a hyperintense FLAIR lesion in the splenium of the corpus callosum. The patient exhibited sudden aggression and combativeness while in the ER and also experienced a second seizure, which prompted immediate intubation. A second MRI with contrast confirmed the presence of the lesion. The patient also underwent electroencephalogram (EEG) monitoring later during his hospital stay, the results of which were unremarkable.

This case report discusses an adult male with NF-1 and a tumor of the splenium of the corpus callosum. The displayed imaging suggested a possible etiology for high seizure frequency in patients with NF-1 compared to the general population.

Targeted Therapies for the Neurofibromatoses

Over the past several years, management of the tumors associated with the neurofibromatoses has been recognized to often require approaches that are distinct from their spontaneous counterparts. Focus has shifted to therapy aimed at minimizing symptoms given the risks of persistent, multiple tumors and new tumor growth. In this review, we will highlight the translation of preclinical data to therapeutic trials for patients with neurofibromatosis, particularly neurofibromatosis type 1 and neurofibromatosis type 2. Successful inhibition of MEK for patients with neurofibromatosis type 1 and progressive optic pathway gliomas or plexiform neurofibromas has been a significant advancement in patient care. Similar success for the malignant NF1 tumors, such as high-grade gliomas and malignant peripheral nerve sheath tumors, has not yet been achieved; nor has significant progress been made for patients with either neurofibromatosis type 2 or schwannomatosis, although efforts are ongoing.

Optic pathway glioma and the sex association in neurofibromatosis type 1: a single-center study

Background

Low-grade optic pathway glioma (OPG) develops in 15–20% of children with neurofibromatosis type 1 (NF1). OPGs are symptomatic in 30–50% and one-third of these require treatment. A few studies have suggested female sex as a risk factor for visual impairment associated with NF1-OPG. This descriptive study investigated the correlation between NF1-OPG growth, sex and visual impairment.

Method

We based our cross-sectional study on a systematic, retrospective data collection in a NF1 cohort of children and adolescents below 21 years of age followed at Center for Rare Diseases, Aarhus University Hospital, Denmark. For each patient with OPG a medical chart review was performed including demographics, ophthalmological examinations and magnetic resonance imaging (MRI) of OPG.

Results

Of 176 patients with NF1 (85 females, 91 males), we identified 21 patients with OPG (11.9%) with a preponderance of females, p = 0.184. Eight females (62%) and one male (13%) had visual impairment at the last ophthalmological evaluation. Five out of 21 children with OPG (24%) underwent diagnostic MRI because of clinical findings at the ophthalmological screening. Nine children (43%) had symptoms suggestive of OPG and seven (33%) experienced no OPG-related symptoms before the diagnostic MRI. Of eight children diagnosed with OPG ≤ two years of age, one had visual impairment. Of 13 children diagnosed > two years of age, eight had visual impairment; in each group, four of the children were treated with chemotherapy. The study suggested no correlation between NF1-OPG growth and sex.

Conclusion

Our data suggest sex as a risk factor for visual impairment, while an OPG diagnose ≤ two years of age was a protective factor for visual impairment. Females with NF1-OPG had a higher prevalence of visual impairment outcome compared to males. Interestingly, our data also suggest a better response to treatment in children with OPG diagnosed ≤ two years of age compared to older children. The findings in our study suggest sex as a potential prognostic factor for visual impairment.

Brain Cancers in Genetic Syndromes

PURPOSE OF REVIEW

Although genetic conditions that cause primary central nervous system tumors are rare, their pathophysiology influences both treatment and surveillance. This article reviews the most frequently occurring genetic conditions associated with brain cancers and highlights the most recent therapeutic approaches in the treatment of Lynch syndrome (and other disorders of the mismatch repair system), neurofibromatosis 1, and Li-Fraumeni syndrome.

RECENT FINDINGS

Recent advances in molecular diagnostics have considerably improved the ability to diagnose genetic conditions in people with primary brain tumors. The common application of next-generation sequencing analyses of tissue increases the frequency with which clinicians are forced to address the possibility of an underlying genetic condition based on tissue molecular findings. Clinicians must be aware of the clinical presentation of genetic conditions predisposing to brain tumors in order to discern which patients are appropriate for germline genetic testing. Advances in therapeutics for specific genetic variants are increasingly available, and accurately diagnosing an underlying genetic condition may directly impact patient outcomes.