Optic pathway gliomas in neurofibromatosis-1: controversies and recommendations

High Incidence of Noonan Syndrome Features Including Short Stature and Pulmonic Stenosis in Patients carrying NF1 Missense Mutations Affecting p.Arg1809: Genotype-Phenotype Correlation

Neurofibromatosis type 1 (NF1) is one of the most frequent genetic disorders, affecting 1:3,000 worldwide. Identification of genotype-phenotype correlations is challenging because of the wide range clinical variability, the progressive nature of the disorder, and extreme diversity of the mutational spectrum. We report 136 individuals with a distinct phenotype carrying one of five different NF1 missense mutations affecting p.Arg1809. Patients presented with multiple café-au-lait macules (CALM) with or without freckling and Lisch nodules, but no externally visible plexiform neurofibromas or clear cutaneous neurofibromas were found. About 25% of the individuals had Noonan-like features. Pulmonic stenosis and short stature were significantly more prevalent compared with classic cohorts (P < 0.0001). Developmental delays and/or learning disabilities were reported in over 50% of patients. Melanocytes cultured from a CALM in a segmental NF1-patient showed two different somatic NF1 mutations, p.Arg1809Cys and a multi-exon deletion, providing genetic evidence that p.Arg1809Cys is a loss-of-function mutation in the melanocytes and causes a pigmentary phenotype. Constitutional missense mutations at p.Arg1809 affect 1.23% of unrelated NF1 probands in the UAB cohort, therefore this specific NF1 genotype-phenotype correlation will affect counseling and management of a significant number of patients.

Strabismus in patients with neurofibromatosis type 1-associated optic pathway glioma

PURPOSE

To characterize the incidence, type, natural history, and treatment outcomes of strabismus in pediatric patients with neurofibromatosis type 1 (NF1) and optic pathway glioma (OPG).

METHODS

The medical records of consecutive patients diagnosed with NF1 and OPG at our neurofibromatosis clinic since 1985 were reviewed retrospectively. We noted age at diagnosis, reason for referral to our clinic, ophthalmologic examination results, presence or absence of strabismus, strabismus type and treatment, and final results of treatment.

RESULTS

A total of 76 patients were included. Of these, 22 (28.9%) had strabismus: 5 (22.7%) had esotropia and 17 (77.2%) had exotropia; of those with exotropia, 10 (45%) also had hypotropia. In 12 patients (54.5%), strabismus was present at the first ophthalmologic examination. The development of strabismus preceded the diagnosis of both NF1 and OPG in 4 (5.3%) patients and the diagnosis of OPG in another 2 (2.6%) patients with known NF1. In 16 (76%) patients, the strabismus was sensory. Five patients (22.7%) underwent surgery, which resulted in a deviation angle of <10(Δ) in 1 patient, <20(Δ) in 2 patients, and >20(Δ) in 2 patients.

CONCLUSIONS

Strabismus was the presenting symptom and led to the diagnosis of OPG in a subset of patients, including those who did not have a previous diagnosis of NF1. Exotropia, especially associated with a hypotropia, was the most common strabismic deviation seen in these patients. Sensory strabismus was the most common type seen in this population. Deviations of <10(Δ) may be difficult to achieve with strabismus surgery.

The Use of Magnetic Resonance Imaging Screening for Optic Pathway Gliomas in Children with Neurofibromatosis Type 1

OBJECTIVE

To evaluate the utility of screening brain/orbital magnetic resonance imaging (MRI) in a large population of children with neurofibromatosis type 1 (NF1) over a 20-year period.

STUDY DESIGN

A retrospective analysis of clinical and imaging data from children with NF1 seen at a single center between 1990 and 2010 was performed.

RESULTS

During the 20-year study period, 826 individuals with NF1 (402 females, 424 males) ages 1-9 years were screened for optic pathway gliomas (OPGs) using brain/orbital MRI; 18% were identified with OPGs with a median age at detection of 3 years. Fifteen percent of patients with OPGs had radiologic or clinical progression requiring therapy. Children with chiasmatic and postchiasmatic tumors were more likely to require therapy compared with patients with prechiasmatic OPGs (P < .0001). Patients with visual deficits at the time of diagnosis were more likely to experience visual decline despite therapy when compared with patients treated based on radiologic progression (P < .012).

CONCLUSIONS

Our findings confirm that chiasmatic and postchiasmatic OPG in children with NF1 have the highest risk for progression and vision loss. Early identification of OPG by screening MRI prior to the development of vision loss may lead to improved visual outcomes. Children with negative brain and orbital MRI screening at age 15 months or later did not develop symptomatic OPGs.

Low-grade gliomas in children: single institutional experience in 198 cases

INTRODUCTION

In pediatric population (0-18 years), low-grade gliomas (PLGG) are the most frequent brain tumors and majority are amenable for surgical removal.

PATIENTS AND METHODS

A retrospective review of 198 children diagnosed with PLGG between 1980 and 2010 at HSJD was carried out. Several variables were studied to find prognostic factors related to the outcomes (progression-free survival (PFS) and overall survival (OS)).

RESULTS

Median age at onset was 88.8 months (3.1 to 214.5 months, SD 53). Surgery was performed in 175 patients (88.4%), achieving gross total resection (GTR) in 77 (44%), subtotal resection (STR) in 87 (49.7%), and 11 (6.3%) biopsies. Pathological review classified 84 tumors as WHO grade I (48%) and 89 as grade II (50.8%). Adjuvant therapy (AT) was given to 75 patients (37.9%), radiotherapy in 24 (12.1%), chemotherapy in 33 (16.7%), and combined in 18 (9.1%). Sixteen patients (8.1%) died, 89 (43.4%) are alive with no evidence of disease, and 93 (47%) alive with disease, median follow-up 65.2 months. Outcome is significantly correlated with age (p = 0001, worse OS for patients younger than 12 months) and extent of tumor resection (p < 0001). OS for GTR/STR/biopsy was >200, 154.3, and 101.9 months, respectively. Patients treated with AT presented worse OS/PFS (p < 0.001) than those not treated. Histology was non significantly related to outcomes.

CONCLUSION

In our series of PLGG, the best prognostic markers are tumor location (cerebellar) and the extent of tumor resection (GTR). Infants and patients who require adjuvant therapy because of tumor progression or recurrence have worse outcome.

Unusual limbal lesion in neurofibromatosis type 1

PURPOSE

To describe an unusual limbal lesion clinically resembling pterygium in a young patient with neurofibromatosis type 1.

METHODS

Clinical case report with a review of the literature.

RESULTS

The lesion was excised, and histopathology was performed. Histopathology disclosed conjunctival mucosa with expansion of the substantia propria by dense and loose collagenous tissue, small nerves, and thin-walled blood vessels. No skin or skin appendages were seen, although a small amount of mature adipose was present. Focally, spindle cells with wavy nuclei were seen scattered within the collagenous areas and were positive on S100 immunohistochemistry. Mast cells were readily identifiable. There was no evidence of actinic elastosis, dysplasia, or malignancy. These histopathological features most resemble heterotopia with some features of neurofibroma.

CONCLUSIONS

We report an unusual limbal lesion in a patient with neurofibromatosis type 1. Histopathological features resemble a heterotopia with some neurofibroma features. We suggest that all lesions excised from patients with neurofibromatosis, no matter how characteristic in appearance, be sent for histopathological confirmation of diagnosis.

Risk of optic pathway glioma in children with neurofibromatosis type 1 and optic nerve tortuosity or nerve sheath thickening

BACKGROUND/AIMS

Optic nerve tortuosity and nerve and sheath thickening are observed on MRI in some patients with neurofibromatosis type 1 (NF-1). This study aimed to determine if tortuosity and thickening are associated with the development of optic pathway glioma (OPG) and subsequent vision loss.

METHODS

Children with NF-1 who underwent brain MRI between 1992 and 2005, and had at least 1 year of subsequent visual acuity (VA) follow-up, were identified retrospectively. The baseline MRI was independently reviewed by three neuroradiologists for consensus assessment. Tortuosity was identified using validated operational criteria. Optic nerve and sheath thicknesses and VA at last follow-up were directly measured.

RESULTS

Of 132 evaluable children, seven (5%) had tortuosity on baseline MRI. 20 subjects (15%) ultimately developed OPG at a median of 1.9 years (range 7 months-8.0 years) following the baseline MRI. Subjects with tortuosity were significantly more likely to develop OPG than those without tortuosity (57% vs 13%, p=0.01). In subjects who developed OPG, the prevalence of tumour-related vision loss was not significantly different between those with and without baseline tortuosity (14% vs 4%, p=0.28). No difference existed between mean baseline optic nerve (2.3 vs 2.2 mm) or sheath (5.2 vs 5.4 mm) thicknesses comparing subjects who did and did not develop OPG.

CONCLUSIONS

Optic nerve tortuosity at baseline is associated with OPG development among patients with NF-1, but does not predispose to aggressive OPG with associated vision loss. Neither nerve nor sheath thickening at baseline is associated with OPG development.

Spontaneous Regression of a Massive Sporadic Chiasmal Optic Pathway Glioma

Optic pathway gliomas have highly variable and unpredictable natural histories, including spontaneous regression, making management decisions difficult and controversial. We report a case of substantial spontaneous regression of an optic pathway glioma involving the chiasm in a 15-month-old boy. Our case is particularly striking given the massive size at presentation with chiasmal, bilateral optic tract, and midbrain involvement, along with clinical ophthalmologic signs for which the majority of practitioners may have recommended treatment on presentation.

The effect of chemotherapy on optic pathway gliomas and their sub-components: A volumetric MR analysis study

BACKGROUND

Optic pathway gliomas (OPG) represent 5% of pediatric brain tumors and compose a major therapeutic dilemma to the treating physicians. While chemotherapy is widely used for these tumors, our ability to predict radiological response is still lacking. In this study, we use volumetric imaging to examine in detail the long-term effect of chemotherapy on the tumor as well as its various sub-components.

PROCEDURE

The tumors of 15 patients with OPG, treated with chemotherapy, were longitudinally measured using our novel, previously described volumetric method. Patients were treated with up to five lines of chemotherapy. Sufficient follow-up imaging data, and patient's numbers, allowed for analysis of two treatment lines. Volumetric measurements of the tumors were segmented into solid-non-enhancing, solid-enhancing, and cystic components. Outcome analysis was done per specific treatment line and for the overall follow-up period.

RESULTS

An average reduction of 9.7% (±23%) in the gross-total-solid volume (GTSV) was noted following treatment with vincristine and carboplatin. The cystic component grew under therapy by an average of 12.6% (±39%). When measured over the course of the whole study period, the cystic component grew by an average of 35% (±100%) and the GTSV increased by 12% (±35%).

CONCLUSION

Initial treatment with vincristine and carboplatin seems to have a minimal initial effect, mostly on the solid components. The cystic component in itself seems to be unaffected by chemotherapy, and contributes to the subsequent growth of the total volume. During the overall treatment period, both solid and cystic components grew regardless of combined treatment methods.

Comparative study of the ophthalmological examinations in neurofibromatosis type 1. Proposal for a new screening algorithm

PURPOSE

Efforts are made to unify the protocol concerning the ophthalmological screening, monitoring and treatment of Optic Pathway Gliomas (OPGs) in children with neurofibromatosis type 1 (NF1). The aim of this study is to compare the most recent recommendations published in 2007 with the screening strategies in NF1 centres. The integration of these data resulted into a recommendation for an improved screening strategy.

METHODS

A literature search on PubMed between 1984 and 2013 was performed. A questionnaire on the ophthalmological screening in NF1 was sent to centres of expertise in the field of NF1. Literature and questionnaire data were analysed. Also, findings of a round table discussion on the ophthalmological screening of NF1 patients at the European Paediatric Ophthalmological Society (EPOS) meeting in 2013 were summarized.

RESULTS

In most centres ophthalmological screening in NF1 patients is well organized, but is performed longer and at more regular intervals than is mentioned in the recommendations. Visual acuity testing, fundoscopy and pupillary reflexes are carried out unanimously.

CONCLUSIONS

There is no uniformity of the ophthalmological screening in NF1 patients. The present recommendation advises to screen annually until the age of 8. Because OPGs are likely to develop before the age of 6 and children do not usually complain of visual problems, OPGs can be missed or detection can be delayed if screening is only yearly performed at this young age. Based on these arguments, about half of our responders screen more frequently and until a later age. Therefore, we suggest performing a six monthly screening until the age of 6 and a yearly examination from 6 years until adulthood. This examination should include visual acuity assessment, pupillary reflexes and a fundoscopy.

Rare case of optic pathway glioma with extensive intra-ocular involvement in a child with neurofibromatosis type 1

We present a case of a 3-year-old girl with a positive family history of neurofibromatosis type-1 (NF1) presented with best corrected visual acuity of 20/40 in the right eye and <20/400 in the left eye. External ocular examination revealed left eye proptosis of 3 mm, grade II left relative afferent pupillary defect and full range of ocular motility with no strabismus. Slit lamp examination revealed iris lisch nodules bilaterally. Dilated fundus examination of the right eye was normal. Left eye disclosed a large mass extending from the optic nerve head, with associated subretinal fluid. There was neovascularization at the optic disc as well as a superior retinal hemorrhage. Computed tomography of brain/orbits showed an enlarged left optic nerve with a large mass at the optic nerve head, with no evidence of calcification. In addition, a large left optic pathway glioma (OPG), multiple hamartomas within the brain and a smaller low-grade right OPG was also reported. The remarkable feature of our case is the rare intraocular optic nerve involvement of the OPG. Early and regular ophthalmological assessment of all NF1 suspect/confirmed cases is of paramount importance in order to detect OPG early, resulting in timely intervention and salvage of vision.

Lisch and the Importance of His Nodules

Neurofibromatosis 1 is the commonest neurocutaneous autosomal dominant disorder with full penetrance, although expression may not be complete by the age of five years. Lisch nodules, however, are predominantly visible in children usually after the age of six years. Therefore, it is important to appreciate that their absence before this age does not pre-empt the diagnosis. A child being treated for hypertension of unknown aetiology with cafe au lait lesions presented to the ophthalmologist with blurred vision. Clinical examination revealed Lisch nodules which confirmed the suspicion of neurofibromatosis 1 as per National Institutes of Health criteria. The aim of this report is to highlight the importance of regular ophthalmic screening, both in suspected and confirmed cases, as these patients have long-term sequelae.

Improving outcomes for neurofibromatosis 1-associated brain tumors

Children and adults with neurofibromatosis type 1 (NF1) are predisposed to developing CNS tumors, including optic pathway gliomas (OPGs), brainstem gliomas (BSGs) and high-grade gliomas. Although current first-line treatments for low-grade gliomas (OPGs and BSGs) may prevent further tumor growth, they rarely result in restoration of the associated visual or neurological deficits. The availability of accurate small-animal models of NF1-associated brain tumors has established tractable experimental platforms for the discovery and evaluation of promising therapeutic agents. On the basis of these preclinical studies, biologically targeted agents are now being evaluated in children with NF1-associated low-grade brain tumors. Collectively, these models have also begun to reveal potential neuroprotective and risk assessment strategies for this brain tumor-prone population.

Optic pathway gliomas

Optic pathway gliomas (OPGs) are among the most challenging neoplasms in modern pediatric neuro-oncology. Recent technological advances in imaging, surgery, and chemotherapy may lead to better understanding of the pathophysiology and better clinical results. This chapter reviews these advances and the current treatment paradigms.

The cyclic AMP pathway is a sex-specific modifier of glioma risk in type I neurofibromatosis patients

Identifying modifiers of glioma risk in patients with type I neurofibromatosis (NF1) could help support personalized tumor surveillance, advance understanding of gliomagenesis, and potentially identify novel therapeutic targets. Here, we report genetic polymorphisms in the human adenylate cyclase gene adenylate cyclase 8 (ADCY8) that correlate with glioma risk in NF1 in a sex-specific manner, elevating risk in females while reducing risk in males. This finding extends earlier evidence of a role for cAMP in gliomagenesis based on results in a genetically engineered mouse model (Nf1 GEM). Thus, sexually dimorphic cAMP signaling might render males and females differentially sensitive to variation in cAMP levels. Using male and female Nf1 GEM, we found significant sex differences exist in cAMP regulation and in the growth-promoting effects of cAMP suppression. Overall, our results establish a sex-specific role for cAMP regulation in human gliomagenesis, specifically identifying ADCY8 as a modifier of glioma risk in NF1.

[Phenotypic and genetic features in neurofibromatosis type 1 in children]

INTRODUCTION

Neurofibromatosis type 1 (NF1) is the most common neurocutaneous disease, nevertheless the number of publications providing clinical and genetic data from a significant number of children is limited.

MATERIAL AND METHODS

The available clinical, epidemiological, radiological and genetic data from 239 children with NF1, who attended at a specialist NF1 clinic between January 2011 and December 2013 were recorded.

RESULTS

All the 239 patients had a clinical and/or genetic diagnosis of NF1. The mean age at diagnosis was 2.65±2.85 years. In our series 99.6% met the diagnostic criteria of café au lait spots, 93.7% those of axillary and inguinal freckling, 7.1% showed typical bone lesion, 38.1% neurofibromas, 23% plexiform neurofibromas, 31.4% optic pathway glioma, Lisch nodules were present in 43.1%, and 28% patients had a first degree relative affected with NF1. The NF1 genetic study was performed in 86 patients, and a description of the gene mutations found in 72 of them is presented. Furthermore, other clinical data previously associated with NF1, either because of their frequency or their severity, are detailed.

CONCLUSIONS

The difficulty for clinical diagnosis of NF1 early ages is still evident. Although, the need for further studies in asymptomatic patients is discussed, cranial MRI in children with NF1 may be helpful in the clinical diagnosis, given the high frequency of optic glioma observed in this cohort.

Akt- or MEK-mediated mTOR inhibition suppresses Nf1 optic glioma growth

BACKGROUND

Children with neurofibromatosis type 1 (NF1) develop optic pathway gliomas, which result from impaired NF1 protein regulation of Ras activity. One obstacle to the implementation of biologically targeted therapies is an incomplete understanding of the individual contributions of the downstream Ras effectors (mitogen-activated protein kinase kinase [MEK], Akt) to optic glioma maintenance. This study was designed to address the importance of MEK and Akt signaling to Nf1 optic glioma growth.

METHODS

Primary neonatal mouse astrocyte cultures were employed to determine the consequence of phosphatidylinositol-3 kinase (PI3K)/Akt and MEK inhibition on Nf1-deficient astrocyte growth. Nf1 optic glioma-bearing mice were used to assess the effect of Akt and MEK inhibition on tumor volume, proliferation, and retinal ganglion cell dysfunction.

RESULTS

Both MEK and Akt were hyperactivated in Nf1-deficient astrocytes in vitro and in Nf1 murine optic gliomas in vivo. Pharmacologic PI3K or Akt inhibition reduced Nf1-deficient astrocyte proliferation to wild-type levels, while PI3K inhibition decreased Nf1 optic glioma volume and proliferation. Akt inhibition of Nf1-deficient astrocyte and optic glioma growth reflected Akt-dependent activation of mammalian target of rapamycin (mTOR). Sustained MEK pharmacologic blockade also attenuated Nf1-deficient astrocytes as well as Nf1 optic glioma volume and proliferation. Importantly, these MEK inhibitory effects resulted from p90RSK-mediated, Akt-independent mTOR activation. Finally, both PI3K and MEK inhibition reduced optic glioma-associated retinal ganglion cell loss and nerve fiber layer thinning.

CONCLUSION

These findings establish that the convergence of 2 distinct Ras effector pathways on mTOR signaling maintains Nf1 mouse optic glioma growth, supporting the evaluation of pharmacologic inhibitors that target mTOR function in future human NF1-optic pathway glioma clinical trials.

Neurofibromatosis type 1: a single center's experience in Korea

Purpose

Neurofibromatosis 1 (NF1) is an autosomal dominant condition caused by an NF1 gene mutation. NF1 is also a multisystem disorder that primarily affects the skin and nervous system. The goal of this study was to delineate the phenotypic characterization and assess the NF1 mutational spectrum in patients with NF1.

Methods

A total of 42 patients, 14 females and 28 males, were enrolled in this study. Clinical manifestations and results of the genetic study were retrospectively reviewed.

Results

Age of the patients at the time of NF1 diagnosis was 15.8±14.6 years (range, 1-62 years). Twelve patients (28.6%) had a family history of NF1. Among the 42 patients, Café-au-lait spots were shown in 42 (100%), neurofibroma in 31 (73.8%), freckling in 22 (52.4%), and Lisch nodules in seven (16.7%). The most common abnormal finding in the brain was hamartoma (20%). Mental retardation was observed in five patients (11.9%), seizures in one patient (2.4%), and plexiform neurofibromas (PNFs) in four patients (9.5%). One patient with PNFs died due to a malignant peripheral nerve sheath tumor in the chest cavity. Genetic analysis of seven patients identified six single base substitutions (three missense and three nonsense) and one small deletion. Among these mutations, five (71.4%) were novel (two missense mutations: p.Leu1773Pro, p.His1170Leu; two nonsense mutations: p.Arg2517^*, p.Cys2371^*; one small deletion: p.Leu1944Phefs^*6).

Conclusion

The clinical characteristics of 42 Korean patients with NF1 were extremely variable and the mutations of the NF1 gene were genetically heterogeneous with a high mutation-detection rate.

Optic pathway gliomas in adults

BACKGROUND

Optic pathway gliomas (OPGs) are considered relatively benign pediatric tumors. Adult patients with OPG can be divided into 2 groups: adult patients with tumors diagnosed in childhood and adult patients diagnosed during adulthood.

OBJECTIVE

To characterize the clinical course of adult patients with OPG.

METHODS

We retrospectively collected clinical and imaging data of all adult OPG patients monitored in our medical center between 1990 and 2012.

RESULTS

Twenty-two adult patients were included. Age at diagnosis varied widely (6 months-66 years), as did age at last follow-up (18-74 years). Ten patients were diagnosed at adulthood and 12 in childhood. Of the patients diagnosed at childhood, 6 had radiological progression during childhood, and 3 of those patients suffered visual impairment. From this group, 1 patient had further progression during adulthood accompanied by additional visual decline, and 2 patients had additional visual decline during adulthood despite no signs of progression. Of the 6 patients whose tumors were stable during childhood, all 6 remained stable during adulthood. Of 10 patients diagnosed at adulthood, 6 patients suffered visual deterioration; in 5 of them, a concomitant progression was noted. Two patients were diagnosed with high-grade gliomas.

CONCLUSION

OPGs may be active during childhood or adulthood. Those patients who experienced anatomic activity during childhood are prone to continue experiencing active disease during adulthood. A significant percentage of patients diagnosed with low-grade OPG at adulthood may suffer progression, visual decline, or both.

ABBREVIATIONS

NF1, neurofibromatosis 1OPG, optic pathway gliomas.

Management of familial cancer: sequencing, surveillance and society

The clinical management of familial cancer begins with recognition of patterns of cancer occurrence suggestive of genetic susceptibility in a proband or pedigree, to enable subsequent investigation of the underlying DNA mutations. In this regard, next-generation sequencing of DNA continues to transform cancer diagnostics, by enabling screening for cancer-susceptibility genes in the context of known and emerging familial cancer syndromes. Increasingly, not only are candidate cancer genes sequenced, but also entire 'healthy' genomes are mapped in children with cancer and their family members. Although large-scale genomic analysis is considered intrinsic to the success of cancer research and discovery, a number of accompanying ethical and technical issues must be addressed before this approach can be adopted widely in personalized therapy. In this Perspectives article, we describe our views on how the emergence of new sequencing technologies and cancer surveillance strategies is altering the framework for the clinical management of hereditary cancer. Genetic counselling and disclosure issues are discussed, and strategies for approaching ethical dilemmas are proposed.

The impact of coexisting genetic mutations on murine optic glioma biology

BACKGROUND

Children with the neurofibromatosis type 1 (NF1) tumor predisposition syndrome are prone to the development of optic pathway gliomas resulting from biallelic inactivation of the NF1 gene. Recent studies have revealed the presence of other molecular alterations in a small portion of these NF1-associated brain tumors. The purpose of this study was to leverage Nf1 genetically engineered mouse strains to define the functional significance of these changes to optic glioma biology.

METHODS

Nf1+/- mice were intercrossed with Nf1(flox/flox) mice, which were then crossed with Nf1(flox/flox); GFAP-Cre mice, to generate Nf1(flox/mut); GFAP-Cre (FMC) mice. These mice were additionally mated with conditional KIAA1549:BRAF knock-in or Pten(flox/wt) mice to generate Nf1(flox/mut); f-BRAF; GFAP-Cre (FMBC) mice or Nf1(flox/mut); Pten(flox/wt); GFAP-Cre (FMPC) mice, respectively. The resulting optic gliomas were analyzed for changes in tumor volume, proliferation, and retinal ganglion cell loss.

RESULTS

While KIAA1549:BRAF conferred no additional biological properties on Nf1 optic glioma, FMPC mice had larger optic gliomas with greater proliferative indices and microglial infiltration. In addition, all 3 Nf1 murine optic glioma strains exhibited reduced retinal ganglion cell survival and numbers; however, FMPC mice had greater retinal nerve fiber layer thinning near the optic head relative to FMC and FMBC mice.

CONCLUSIONS

Collectively, these experiments demonstrate genetic cooperativity between Nf1 loss and Pten heterozygosity relevant to optic glioma biology and further underscore the value of employing genetically engineered mouse strains to define the contribution of discovered molecular alterations to brain tumor pathogenesis.

Neurofibromatosis type 1: a multidisciplinary approach to care

Neurofibromatosis type 1 is a relatively common inherited disorder. Patients have a high predisposition to develop both benign and malignant tumours. Although many manifestations of neurofibromatosis type 1 affect the nervous system, other organs and tissues can also be affected. Because of the varying features and clinical heterogeneity inherent to this disorder, patients can present to different medical and surgical specialists and, therefore, the association of clinical symptoms with neurofibromatosis type 1 might not be appreciated. Thus, for prompt diagnosis and to provide optimum care for patients with neurofibromatosis type 1, clinicians must be aware of the diverse clinical features of this disorder. We advocate a multidisciplinary approach to care, entailing a dedicated team of specialists throughout the lifetime of the patient. As our understanding of this disorder deepens through basic laboratory and clinical investigations, swift implementation of new effective treatments becomes feasible.

Is it time to change the neurofibromatosis 1 diagnostic criteria?

Neurofibromatosis 1 is a complex inherited neurocutaneous disease that is often difficult to diagnose early because of its age-dependent presentation. The diagnosis is also extremely difficult to communicate to patients and their parents because of the disease's clinical variability, unpredictable evolution, and uncertain prognosis. Since 1988, the year of publication of the last Consensus Conference statement concerning the diagnosis of neurofibromatosis 1, our understanding of the disease has naturally increased and, in addition to the availability of increasingly precise molecular analyses, some new clinical signs have been reported such as anaemic nevi, unidentified bright objects, choroidal hamartomas, and a typical neuropsychological phenotype. We critically review the current diagnostic criteria, and suggest the addition of new signs on the basis of published findings and our own clinical experience. This proposal aims to improve diagnostic power in paediatric age, securing a better and more reliable healthcare transition toward adult age. We finally recommend a new Consensus Conference in order to revise the diagnostic criteria, possibly differentiated by age of presentation.

Eliminating barriers to personalized medicine: learning from neurofibromatosis type 1

With the emergence of high-throughput discovery platforms, robust preclinical small-animal models, and efficient clinical trial pipelines, it is becoming possible to envision a time when the treatment of human neurologic diseases will become personalized. The emergence of precision medicine will require the identification of subgroups of patients most likely to respond to specific biologically based therapies. This stratification only becomes possible when the determinants that contribute to disease heterogeneity become more fully elucidated. This review discusses the defining factors that underlie disease heterogeneity relevant to the potential for individualized brain tumor (optic pathway glioma) treatments arising in the common single-gene cancer predisposition syndrome, neurofibromatosis type 1 (NF1). In this regard, NF1 is posited as a model genetic condition to establish a workable paradigm for actualizing precision therapeutics for other neurologic disorders.

Anisometropia in children with neurofibromatosis type 1 and unilateral optic nerve glioma

BACKGROUND

Optic nerve glioma (ONG) occurs in 5% to 25% of individuals with neurofibromatosis type 1 (NF1). Recently an association between this lesion and unilateral myopia was reported in a series of 4 pediatric patients. The purpose of this study was to determine whether unilateral ONG is associated with an increased prevalence of anisometropia.

METHODS

The medical records of children <16 years of age with NF1 disease and unilateral ONG or normal neuroimaging examined at Tel-Aviv Medical Center between April 2008 and July 2013 were retrospectively reviewed to determine the prevalence of anisometropia and anisoastigmatism.

RESULTS

A total of 75 children with NF1 disease were included. Of these, 25 (11 boys) had a unilateral ONG (mean age, 7.2 years; range, 2-16 years) and 50 (29 boys) had normal neuroimaging (mean age, 8.3 years; range, 1-15 years). The mean refraction (spherical equivalent) of eyes with ONG did not differ significantly from that of the contralateral eyes (0.74 ± 1.41 D vs 0.71 ± 1.19 D; P = 0.935; 95% CI, -0.710 to 0.770); moreover, there was a high correlation between the refraction of eyes with ONG and contralateral eyes (r = 0.946, P < 0.001). The prevalence of anisometropia in children with ONG and in NF1 children with no orbital pathology did not differ significantly (8% vs 16%; P = 0.480), and the prevalence of anisoastigmatism was also similar in both groups (4% vs 14%, P = 0.255).

CONCLUSIONS

ONG in children with NF1 is not associated with increased prevalence of anisometropia.

Handheld optical coherence tomography during sedation in young children with optic pathway gliomas

IMPORTANCE

Monitoring young children with optic pathway gliomas (OPGs) for visual deterioration can be difficult owing to age-related noncompliance. Optical coherence tomography (OCT) measures of retinal nerve fiber layer (RNFL) thickness have been proposed as a surrogate marker of vision but this technique is also limited by patient cooperation.

OBJECTIVE

To determine whether measures of circumpapillary RNFL thickness, acquired with handheld OCT (HH-OCT) during sedation, can differentiate between young children with and without vision loss from OPGs.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional analysis of a prospective observational study was conducted at a tertiary-care children's hospital. Children with an OPG (sporadic or secondary to neurofibromatosis type 1) who were cooperative for visual acuity testing, but required sedation to complete magnetic resonance imaging, underwent HH-OCT imaging of the circumpapillary RNFL while sedated.

MAIN OUTCOMES AND MEASURES

Area under the curve of the receiver operating characteristic, sensitivity, specificity, positive predictive value, and negative predictive value of the average and quadrant-specific RNFL thicknesses.

RESULTS

Thirty-three children (64 eyes) met inclusion criteria (median age, 4.8 years; range, 1.8-12.6 years). In children with vision loss (abnormal visual acuity and/or visual field), RNFL thickness was decreased in all quadrants compared with the normal-vision group (P < .001 for all comparisons). Using abnormal criteria of less than 5% and less than 1%, the area under the curve was highest for the average RNFL thickness (0.96 and 0.97, respectively) compared with specific anatomic quadrants. The highest discrimination and predictive values were demonstrated for participants with 2 or more quadrants meeting less than 5% (sensitivity = 93.3; specificity = 97.9; positive predictive value = 93.3; and negative predictive value = 97.9) and less than 1% (sensitivity = 93.3; specificity = 100; positive predictive value = 100; and negative predictive value = 98.0) criteria.

CONCLUSIONS AND RELEVANCE

Measures of RNFL thickness acquired with HH-OCT during sedation can differentiate between young children with and without vision loss from OPGs. For young children who do not cooperate with vision testing, HH-OCT measures may be a surrogate marker of vision. Longitudinal studies are needed to delineate the temporal relationship between RNFL decline and vision loss.

Prolonged survival in adult neurofibromatosis type I patients with recurrent high-grade gliomas treated with bevacizumab

Astrocytic tumors, especially optic pathway pilocytic astrocytomas, are common in pediatric NF1 patients. High-grade gliomas (HGGs) appear to be rare in adult and pediatric NF1 patients. This is a series of five consecutive, adult NF1 patients with recurrent HGGs treated at The University of Texas MD Anderson Cancer Center. Four patients met consensus clinical criteria for NF1 and one patient had presumed segmental NF1. Three patients had glioblastomas, one gliosarcoma, and one progressive, enhancing optic pathway glioma which was not biopsied. Two tumors had molecular testing performed; both were IDH wild type and activating oncogene mutations (1 BRAFV600E and 1 PIK3CA mutation) were found in these tumors. All five patients received bevacizumab-containing regimens at tumor recurrence. The median number of 4-week cycles of bevacizumab was 20. All five patients experienced prolonged post-recurrence survival following bevacizumab treatment ranging from ten to 72 months. The median overall survival from HGG diagnosis was 72.6 months with three patients alive and progression free at last follow-up. Three out of five patients developed vascular complications leading to bevacizumab discontinuation. In this case series, adult NF1 patients with recurrent HGGs had prolonged, post-recurrence survival after treatment with bevacizumab-containing regimens. Based on these results, further study of antiangiogenic therapy in NF1 patients with HGGs and bevacizumab-response in sporadic HGG patients with NF1-mutated tumors is warranted.

Non-compressive disorders of the chiasm

Chiasmal dysfunction produces a characteristic clinical picture, regardless of the mechanism. In most cases a compressive lesion is the cause. In occasional cases, however, no such extrinsic mass is found and other possible etiologies must be explored. In some of these cases, the pathologic process is identifiable with appropriate neuroimaging. For example, inflammation, infiltrative tumors, and radiation necrosis produce intrinsic chiasmal enhancement. Chiasmal ischemia may require specialized magnetic resonance (MR) sequences for diagnosis. Chiasmal hemorrhage, trauma and chiasmal herniation typically produce distinctive changes on noncontrasted imaging. In cases of metabolic insult, either toxic or hereditary, radiographic changes are typically absent. In each of these, the correct diagnosis can usually be made with a combination of clinical and radiographic features.

Optical coherence tomography in pediatric ophthalmology: current roles and future directions

The application of existing optical coherence tomography (OCT) technology to the pediatric population is limited in both the design specification of the device and its hardware. However, the potential of OCT in the pediatric population has not been fully realized. The authors review the literature, highlighting the currently available spectral-domain OCT technology and summarizing the reported normal pediatric OCT parameters for retinal nerve fiber layer and macular thickness. They also review the pediatric ophthalmological conditions in which OCT has been used and discuss advancements in OCT design and their potential applications to the pediatric population. The use of OCT in pediatric populations is likely to increase greatly in the coming years, aiding clinical decision-making and providing new insights into pediatric disease pathophysiology.

Advances in paediatric cancer treatment

Four out of five children diagnosed with cancer can be cured with contemporary cancer therapy. This represents a dramatic improvement since 50 years ago when the cure rate of childhood cancer was <25% in the pre-chemotherapy era. Over the past ten years, while improvement in overall survival (OS) has been marginal, progress in pediatric oncology lies with adopting risk-adapted therapeutic approach. This has been made possible through identifying clinical and biologic prognostic factors with rigorous research and stratifying patients using these risk factors, and subsequently modifying therapy according to risk group assignment. This review provides a perspective for eight distinct pediatric malignancies, in which significant advances in treatment were made in the last decade and are leading to changes in standard of care. This includes four hematologic malignancies [acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL)] and four solid tumors [medulloblastoma (MB), low grade glioma (LGG), neuroblastoma (NB) and Ewing sarcoma (ES)]. Together, they comprise 60% of childhood cancer. Improved patient outcome is not limited to better survival, but encompasses reducing both short and long-term treatment-related complications which is as important as cure, given the majority of childhood cancer patients will become long-term survivors. Risk-adapted approach allows treatment intensification in the high-risk cohort while therapy can be de-escalated in the low-risk to minimize toxicity and late sequelae without compromising survival. Advances in medical research technology have also led to a rapid increase in the understanding of the genetics of childhood cancer in the last decade, facilitating identification of molecular targets that can potentially be exploited for therapeutic benefits. As we move into the era of targeted therapeutics, searching for novel agents that target specific genetic lesions becomes a major research focus. We provide an overview of seven novel agents (bevacizumab, bortezomib, vorinostat, sorafenib, tipifarnib, erlotinib and mTOR inhibitors), which have been most frequently pursued in childhood cancers in the last decade, as well as reporting the progress of clinical trials involving these agents.

Activation of Sonic hedgehog signaling in neural progenitor cells promotes glioma development in the zebrafish optic pathway

Dysregulation of Sonic hedgehog (Shh) signaling has been implicated in glioma pathogenesis. Yet, the role of this pathway in gliomagenesis remains controversial because of the lack of relevant animal models. Using the cytokeratin 5 promoter, we ectopically expressed a constitutively active zebrafish Smoothened (Smoa1) in neural progenitor cells and analyzed tumorigenic capacity of activated Shh signaling in both transient and stable transgenic fish. Transient transgenic fish overexpressing Smoa1 developed retinal and brain tumors, suggesting smoa1 is oncogenic in the zebrafish central nervous system (CNS). We further established stable transgenic lines that simultaneously developed optic pathway glioma (OPG) and various retinal tumors. In one of these lines, up to 80% of F1 and F2 fish developed tumors within 1 year of age. Microarray analysis of tumor samples showed upregulated expression of genes involved in the cell cycle, cancer signaling and Shh downstream targets ptc1, gli1 and gli2a. Tumors also exhibited specific gene signatures characteristic of radial glia and progenitor cells as transcriptions of radial glia genes cyp19a1b, s100β, blbp, gfap and the stem/progenitor genes nestin and sox2 were significantly upregulated. Overexpression of GFAP, S100β, BLBP and Sox2 was confirmed by immunofluorescence. We also detected overexpression of Mdm2 throughout the optic pathway in fish with OPG, therefore implicating the Mdm2–Tp53 pathway in glioma pathogenesis. In conclusion, we demonstrate that activated Shh signaling initiates tumorigenesis in the zebrafish CNS and provide the first OPG model not associated with neurofibromatosis 1.

Ganglion cell layer-inner plexiform layer thickness and vision loss in young children with optic pathway gliomas

PURPOSE

To determine if measures of macular ganglion cell layer-inner plexiform layer (GCL-IPL) thickness can discriminate between children with and without vision loss (visual acuity or field) from their optic pathway glioma (OPG) using spectral-domain optical coherence tomography (SD-OCT).

METHODS

Children with OPGs (sporadic or secondary to neurofibromatosis type 1) enrolled in a prospective study of SD-OCT were included if they were cooperative for vision testing and macular SD-OCT images were acquired. Manual segmentation of the macular GCL-IPL and macular retinal nerve fiber layer (RNFL) was performed using elliptical annuli with diameters of 1.5, 3.0, and 4.5 mm. Logistic regression assessed the ability of GCL-IPL and RNFL thickness measures (micrometers) to differentiate between the normal and abnormal vision groups.

RESULTS

Forty-seven study eyes (normal vision = 31, abnormal vision = 16) from 26 children with OPGs were included. Median age was 5.3 years (range, 2.5-12.8). Thickness of all GCL-IPL and RNFL quadrants differed between the normal and abnormal vision groups (P < 0.01). All GCL-IPL measures demonstrated excellent discrimination between groups (area under the curve [AUC] > 0.90 for all diameters). Using the lower fifth percentile threshold, the number of abnormal GCL-IPL inner macula (3.0 mm) quadrants achieved the highest AUC (0.989) and was greater than the macula RNFL AUCs (P < 0.05).

CONCLUSIONS

Decreased GCL-IPL thickness (<fifth percentile) can discriminate between children with and without vision loss from their OPG. Ganglion cell layer-inner plexiform layer thickness could be used as a surrogate marker of vision in children with OPGs.

Sex Is a major determinant of neuronal dysfunction in neurofibromatosis type 1

OBJECTIVE

Children with neurofibromatosis-1 (NF1) are at risk for developing numerous nervous system abnormalities, including cognitive problems and brain tumors (optic pathway glioma). Currently, there are few prognostic factors that predict clinical manifestations or outcomes in patients, even in families with an identical NF1 gene mutation. In this study, we leveraged Nf1 genetically engineered mice (GEM) to define the potential role of sex as a clinically relevant modifier of NF1-associated neuronal dysfunction.

METHODS

Deidentified clinical data were analyzed to determine the impact of sex on optic glioma-associated visual decline in children with NF1. In addition, Nf1 GEM were employed as experimental platforms to investigate sexually dimorphic differences in learning/memory, visual acuity, retinal ganglion cell (RGC) death, and Nf1 protein (neurofibromin)-regulated signaling pathway function (Ras activity, cyclic adenosine monophosphate [cAMP], and dopamine levels).

RESULTS

Female patients with NF1-associated optic glioma were twice as likely to undergo brain magnetic resonance imaging for visual symptoms and 3× more likely to require treatment for visual decline than their male counterparts. As such, only female Nf1 GEM exhibited a decrement in optic glioma-associated visual acuity, shorter RGC axons, and attenuated cAMP levels. In contrast, only male Nf1 GEM showed spatial learning/memory deficits, increased Ras activity, and reduced dopamine levels.

INTERPRETATION

Collectively, these observations establish sex as a major prognostic factor underlying neuronal dysfunction in NF1, and suggest that sex should be considered when interpreting future preclinical and clinical study results.

Functional outcome measures for NF1-associated optic pathway glioma clinical trials

OBJECTIVE

The goal of the Response Evaluation in Neurofibromatosis and Schwannomatosis Visual Outcomes Committee is to define the best functional outcome measures for future neurofibromatosis type 1 (NF1)-associated optic pathway glioma (OPG) clinical trials.

METHODS

The committee considered the components of vision, other ophthalmologic parameters affected by OPG, potential biomarkers of visual function, and quality of life measures to arrive at consensus-based, evidence-driven recommendations for objective and measurable functional endpoints for OPG trials.

RESULTS

Visual acuity (VA) assessments using consistent quantitative testing methods are recommended as the main functional outcome measure for NF1-OPG clinical trials. Teller acuity cards are recommended for use as the primary VA endpoint, and HOTV as a secondary endpoint once subjects are old enough to complete it. The optic disc should be assessed for pallor, as this appears to be a contributory variable that may affect the interpretation of VA change over time. Given the importance of capturing patient-reported outcomes in clinical trials, evaluating visual quality of life using the Children's Visual Function Questionnaire as a secondary endpoint is also proposed.

CONCLUSIONS

The use of these key functional endpoints will be essential for evaluating the efficacy of future OPG clinical trials.

The association between hypotonia and brain tumors in children with neurofibromatosis type 1

Children with the neurofibromatosis type 1 (NF1) inherited tumor predisposition syndrome are at risk for the development of brain tumors. In addition, children with neurofibromatosis type 1 often exhibit low tone (hypotonia). In this study, the authors explored the hypothesis that hypotonia could be a clinical indicator of glioma in children with neurofibromatosis type 1. A total of 56 children between 1 and 7 years of age with a confirmed diagnosis of neurofibromatosis type 1 were evaluated. Brain magnetic resonance imaging (MRI) was available for 19 of these children. Chi-square analysis demonstrated a statistically significant correlation between hypotonia and glioma in children with neurofibromatosis type 1 (90% sensitivity and 78% specificity). These results suggest that hypotonia might be a clinically useful indicator of brain tumor in this at-risk population.

Vision specific quality of life in children with optic pathway gliomas

Children with optic pathway gliomas (OPGs) frequently experience vision loss from their tumors. Most pediatric OPG research has focused on radiographic and visual outcomes, yet the impact of vision loss on quality of life (QOL) in children with OPGs has not been studied. The present study prospectively recruited children ≤ 10 years of age with sporadic or neurofibromatosis type 1 (NF1)-related OPGs. Vision specific QOL was assessed by parent proxy using the Children's Visual Function Questionnaire (CVFQ), and scores were analyzed according to magnitude of visual acuity (VA) loss and presence of visual field (VF) loss. Thirty-six subjects completed the study (53 % female) with median age of 4.6 years. Children with mild, moderate and severe vision loss have lower CVFQ subscale scores, indicating a lower vision specific QOL, compared to those with normal vision. Lower Competence scores were noted in participants with more profound vision loss (p < 0.05), reflecting a decreased ability to complete activities of daily living (e.g., feeding, grooming). Children with two visually impaired eyes were rated as having greater difficulty with social interactions and pleasurable activities (Personality subscale, p = 0.039) compared to those with only one impaired eye. In summary, our findings demonstrate that children with vision loss secondary to their OPG have a decreased vision specific QOL compared to those with normal vision. Measuring vision specific QOL may be considered a meaningful secondary outcome measure for pediatric OPG clinical trials.