Optic Pathway Gliomas Research Articles

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.

Prospective registration of symptoms and times to diagnosis in children and adolescents with central nervous system tumors: A study of the Swedish Childhood Cancer Registry.

The elapsed time taken to diagnose tumors of the central nervous system in children and adolescents varies widely. The aim of the present study was to investigate such diagnostic time intervals at a national level in Sweden as they correlate with clinical features. Data prospectively accumulated over a 4-year period in the Swedish Childhood Cancer Registry from patients aged 0-18years were pooled, and diagnostic time intervals were analyzed considering tumor location, tumor type, patient age and sex, initial symptoms, and clinical timelines. All six pediatric oncology centers in Sweden contributed to collection of data. Time points for calculating the total diagnostic interval (TDI) defined as the time from symptom onset to diagnosis were reported in 257 of 319 patients (81%). The time from symptom onset to the first healthcare consultation, median 2.6weeks, did not vary significantly between patients categorized according to tumor type or location. The median TDI was 8.3weeks for the 4-year study period. Patients with optic pathway glioma (TDI 26.6weeks), those with tumors of the spinal cord (TDI 25.9weeks), and those with midline tumors (TDI 24.6weeks) had the longest lead times. Additionally, older age, too few initial symptoms, and seeking initial redress outside an emergency ward were factors associated with a longer time to diagnosis. This study identified several factors associated with delayed diagnosis of central nervous system tumors among Swedish children and adolescents. These novel data ought to help direct future efforts toward clinical improvement.

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

BackgroundOptic 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 MethodsIn 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.ResultsTwenty-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.ConclusionsMany 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.

Characteristics of Moyamoya Syndrome in Pediatric Patients With Neurofibromatosis Type 1

BackgroundMoyamoya syndrome (MMS) is a progressive cerebral arteriopathy with increased incidence in children with neurofibromatosis type 1 (NF1). Despite the potential for significant neurological morbidity including stroke, little is known about the natural history, and no guidelines exist for screening and management of NF1-associated MMS. MethodsWe identified 152 literature cases of children aged ≤18 years with NF1-associated MMS. A meta-analysis was performed evaluating clinical and neuroimaging findings and patient outcomes. Data from 19 patients with NF1-associated MMS from our center treated from January 1995 to July 2020 were abstracted via chart review and similarly analyzed for clinical and neuroimaging features. ResultsMeta-analysis of literature cases showed a median age of MMS diagnosis of 6 years (interquartile range 3 to 10.8 years). Optic pathway gliomas were more common in patients with MMS (42%) compared with historical prevalence. Stroke or transient ischemic attack (TIA) was present at diagnosis in 46%. TIA and stroke were more common in patients with bilateral versus unilateral MMS (62% vs 34%, P = 0.001) and in children aged <4 years versus those aged ≥4 years (61% vs 40%, P = 0.02). Compared with the literature cases, our cohort was more frequently asymptomatic (42% vs 25%) and less likely to present with TIA or stroke (32% vs 46%) at diagnosis. ConclusionsThese data suggest there is an aggressive form of MMS in children with NF1 <4 years of age. Therefore, early screening should be considered to facilitate early detection and treatment of cerebral arteriopathy.

LGG-10. Evaluation of the chemotherapy efficacy of children with optic pathway glioma in a tertiary hospital in China

OBJECTIVE: In order to analyze the chemotherapy efficacy of children with optic pathway glioma (OPG), the clinical, treatment and prognosis factors of children with OPG who received the German International Society of Pediatric Oncology (SIOP) low-grade glioma (LGG) 2004 regimen chemotherapy, were retrospectively analyzed. METHOD: From September 2014 to October 2019, a total of 60 patients with OPG were enrolled and accept LGG 2004 chemotherapy in the Department of Pediatrics, Beijing Shijitan Hospital, Capital Medical University, China. The progression-free survival (PFS) rates and overall survival (OS) rates were analyzed by the Kaplan-Meier method. Both univariate and multivariate analyses were performed using the Cox-proportional hazards model. The test standard α=0.05. RESULTS: Until January 1st, 2022, all children were alive, and the clinical symptoms were improved at any degree, and well tolerated during the whole treatment. The median follow-up time was 3.7 years (range 2.3-7.1 years), the average time of objective response was 6.8 months (range from 2 to 21 months), and the 5 year PFS rates were 73.0 ± 7.24 %. However, about 3 to 8 months later, 8 cases (age <4 years) relapsed which attained partial remission (PR) at the end of the whole therapy. These relapsed cases were performed the LGG 2004 regimen again, and all had an objective response after 4~6 courses of treatment. In addition, two children (age>8 years old) progressed rapidly during treatment, and had to be performed local radiotherapy and reached complete remission (CR). Another two cases with BRAF V600E mutation, reached a significant remission after 3 months of targeted therapy with selumetinib. Furthermore, the COX multivariate analysis shows that spinal metastasis is an independent risk factor of prognosis of children with OPG. CONLUSIONS: Chemotherapy can improve the clinical efficacy of children with OPG, which is better when combining with bevacizumab and/or targeted therapy.

LINC-04. Optic pathway gliomas in children: an 18-year experience in a middle-income country

Abstract BACKGROUND: Optic pathway gliomas (OPGs) have favorable survival outcomes, but can have significant morbidity, from the tumor or from its treatment. This retrospective study sought to describe the clinical presentation and outcomes of children with OPGs at a tertiary center in a middle-income country. METHODS: Patients younger than 18 years diagnosed with OPGs between 2002-2020 at the Hospital Civil de Guadalajara in Mexico, were included. Survival analyses and logistic regression were used to determine risk factors for progression. RESULTS: Thirty patients were identified with a median age of six years. Common clinical characteristics at presentation included: visual accuracy impairment (40%), headache (23.3%), nystagmus (20%), endocrine disturbances (16.6%), and diencephalic syndrome (13%). Neurofibromatosis-1 was present in 23.3% of the patients. Eight patients underwent resection at diagnosis, 7 of them had secondary complications. One died during surgery due to catecholamine-resistant shock, and the other developed neuro-infection and died due to septic shock after surgery. Five children developed neurological or endocrine sequelae. Fifteen total patients received chemotherapy as their first line treatment. The 5-year progression-free survival was 77.9±10% and overall survival was 89.5±5%. Patients who received chemotherapy or targeted therapy as the first line of treatment had higher PFS compared to those who received other therapies (p=0.03). The patients who received surgery as first-line treatment had a 3.1 times greater risk of achieving a Lansky/Karnofsky score of fewer than 90 points 6 months after diagnosis (p=0.006). Ten patients had pre- and post-treatment ophthalmologic assessment, either visual acuity or visual evoqued potentials. Five had no changes and 5 showed improvement after treatment. CONCLUSIONS: These results show inferior outcomes compared to high-income countries, influenced importantly due to morbidity after surgical resection. These data can be used to prospectively optimize treatment at our institute and other middle-income countries through a multidisciplinary neuro-oncology team.

LGG-63 MEK inhibitor-associated retinopathy (MEKAR) in a pediatric patient with an optic pathway glioma

Pediatric low-grade glioma (LGG) and plexiform neurofibroma (PN) universally have up-regulation of the RAS-mitogen-activated protein kinase (MAPK) pathway. Recent phase I and II clinical trials evaluating MEK inhibitors for the treatment pediatric LGG and PN report efficacy and tolerable side effects, including no reported ophthalmologic toxicity. Contrary to the pediatric experience, adult trials using MEK inhibitors describe several ophthalmologic side effects, including MEK inhibitor-associated retinopathy (MEKAR), also termed central serous-like retinopathy. MEKAR is defined as accumulation of subretinal fluid. It occurs in up to 90% of adults on MEK inhibitors, usually causing minimal to no symptoms, and typically resolving without MEK inhibitor dose adjustment. We report a case of MEKAR in a 15 year old boy with an optic pathway pilocytic astrocytoma with duplication of BRAF (7q34). Baseline ophthalmic exam showed 20/20 vision in his right eye with loss of the temporal hemifield and no light perception vision in the left eye. Nine months into treatment with Selumetinib his ophthalmologic exam and optical coherence tomography (OCT) showed asymptomatic bilateral subretinal fluid. Selumetinib was held for 2 weeks resulting in resolution of the subretinal fluid. Selumetib was resumed at the prior dose and MEKAR recurred 2 weeks later but then permanently resolved 4 weeks later despite remaining on Selumetib. Review of the literature discovered a single publication of 2 pediatric patients with optic pathway glioma who developed MEKAR around 6-7 months after initiating Selumetinib, which resolved after stopping Selumetinib. One patient was symptomatic and despite resolution of symptoms, Selumetinib was not resumed. The other patient was asymptomatic and resumed Selumetib, but redeveloped MEKAR 8 months after restarting Selumetinib. Based on adult experience and the limited pediatric experience outlined above, we recommend pediatric patients with asymptomatic and mild-moderate symptomatic MEKAR undergo close monitoring without Selumetinib dose interruption or modification unless symptoms progress.

LGG-64. A Phase II Study of Pegylated Interferon in Children with Recurrent or Refractory and Radiographically or Clinically Progressive Juvenile Pilocytic Astrocytomas and Optic Pathway Gliomas (NCT02343224)

Unresectable Juvenile Pilocytic Astrocytomas (JPA) and Optic Pathway gliomas (OPG) are chronic diseases that can have solid +/- cystic components. We wanted to evaluate the objective response to pegylated interferon Alpha2B in this group of patients in a prospective single arm Phase II clinical trial. Eligibility criteria: age 3 -25 years, patients with neurofibromatosis (NF) were eligible, evidence of measurable disease in MRI, no limitation in the number of prior therapies including chemotherapy and radiation. Exclusion criteria: prior pegylated interferon exposure, less than 2 years from radiation, active autoimmune disease. Subjects enrolled received pegylated interferon 1 mcg/kg/dose SQ weekly, to a max dose of 150mcg/dose in 28 day cycles for up to 2 years. The study design is a Simon two stage design. If no complete or partial responses among the first 9 patients, the study will terminate. Nine subjects enrolled: 4 females, 5 males, median age of 11years, 6 Caucasians, 3 African Americans. Two subjects with NF. Molecular findings KIAA-BRAF fusion (6), V600E mutation (1), CDK2A loss (1). Location: brain (7), brain and spine (2). We enrolled a heavily pre-treated population, patients with prior radiation ( 1), nine with prior chemotherapy, the average number of regimens 4 (range 2-6). No complete responses or partial responses were seen. Two patients with prolonged stable disease 75+months and 66+ months. At 12 and 24 month EFS 76.2% (95%CI52.1-100%). Median EFS has not been reached. The 12 and 24 months survival estimate 75% (95% CI 50.3-100%), median survival has not been reached. Side effects as expected mostly grade 1-2. No grade 4 event related to pegylated interferon were seen. This is the first report of pegylated interferon in OPG and JPA, two patients with prolonged stable disease suggesting that pegylated interferon can offer potential benefit in this population and additional studies are important.

NFB-17. "Optic Pathway findings in children with Neurofibromatosis type-1 (NF-1)

BACKGROUND/OBJECTIVES:Optic-pathway-glioma(OPG) represents the most common central-nervous tumor in children with neurofibromatosis type-1(NF1), occurring at an incidence of 15-20%. It is estimated that 1/3 of NF1 patients(pts) with OPG will need treatment. DESIGN-METHODS:We performed a retrospective-review of all NF1-pts examined in the First Hellenic Multidisciplinary-Clinic – Center of Expertise for Neurocutaneous-disorders. Gender, age, MRI-radiological and ophthalmological findings, presence of OPG, management and outcome were analyzed. RESULTS:Since the establishment of the Clinic in 2016, 198pts with clinical diagnosis of NF1 based on NIH1988-criteria were evaluated and of them, 165(73 females, median age:5.5y, range:0.3-17.1y), who had imaging studies were included in this analysis. Eighty three pts(50.3%) had NF1-positive genetic-testing and 45NF1-family-history(27.3%). Imaging-findings from optic pathway were found in 55/165pts(28females). Percentage of pts with findings were 51.7% for <3y, 45.4% for 3-5y, 34.7% for 5-10y and 8.5% for >10y, respectively. The median age of their first brain-MRI imaging was 2.82y. Upon 1stMRI-imaging, 70.9% presented thickness of the optic nerves(ON)(25,4%bilateral, 20% optic chiasm,18.1% right ON, 10.0% left ON), 14.5%ON-tortuosity, 38.1%OPG(43,5% in the optic-chiasm) and 34.5% contrast enhancement. Of notice, 14pts presented an OPG after a median follow-up time of 1.79y. According to LGG2004-protocol indications for treatment, only 15/55pts had to be treated(27,2%, 5pts with family history, 33.3% between 5-10y). Severe vision-loss with need for immediate start of treatment upon 1stMRI imaging was found in 4pts, of whom 75% had family-history and first evaluation after the 5th year of age. Of notice, only 2pts<3y had to receive treatment, one with family-history and one with symptoms(diencephalic syndrome). CONCLUSIONS: Pts with NF1 should be followed by a multidisciplinary-team. Management should be individualized and imaging-studies can be limited to patients at high-risk. Positive family-history may be a negative prognostic factor for OP lesions.

LGG-37. Long-term Outcome, Visual Morbidity and Prognostic Factors in Infants and Young Children with Optic Pathway Glioma from the Great Ormond Street Hospital (GOSH) LGG - Cohort

INTRODUCTION: The treatment aim of childhood optic pathway glioma (OPG) is visual preservation. However, long-term outcomes and prognostic factors implicated remain largely unknown. METHODS: We undertook a retrospective study of infants and young children (IYC) ≤3 years with OPG and logMAR visual acuity (VA) at baseline/follow-up. We derived Overall- (OS), Progression-free (PFS), Radiotherapy-free (RTFS) and Visual event-free survival (vEFS) curves and analysed prognostic factors for visual deterioration and WHO defined blindness (>1.3 logMAR both eyes). RESULTS: Of 81 IYC-OPG (147 evaluable eyes) baseline vision was below 5%ile for age in 33 (41%) and 27 (33%) in one or both eyes respectively, within normal range in 21 (26%). After observation (11), chemotherapy (66) or RT (4), radiological progression occurred in 47 (58%), multiple times in 34.6% (range 2 - 8) and 10yr-PFS was 39.8%. Twenty had RT after 4.2 years from diagnosis (10yr-RTFS 72.4%) and 12% died (10yr-OS 89%). After 8.9 years VA was better/stable/ worse in 36%/32%/32% of subjects, with median time to visual event of 1.7 years (range 0.16 - 12) and 10yr-vEFS 41.3%. Final VA was reduced (>0.2 logMAR) in 23 (28.4%) and 43 (53.1%) in only one or both eyes respectively. Amongst those with unilateral impairment 13/23 affected eyes had no useful vision (light/no light perception). Amongst those with bilateral impairment best eye VA was > 1.0 log MAR in 22/43 (LP/NLP in 10). Infants < 1 year had significantly inferior 10-yrPFS (5.6%), post-chiasmatic involvement was associated with visual deterioration (HR 2.91, 95%CI=1.1- 7.7), and baseline bilateral abnormal for age vision predicted WHO blindness at follow-up (OR 17.9, 95%CI=3.2 – 101.1). CONCLUSIONS: Many IYC-OPG suffer multiple progressions with significant long-term visual morbidity. Predictive factors such as age, tumor location and baseline age-adjusted vision allow patients’ selection for early sight rehabilitation and consideration for experimental strategies preventing visual loss.

LGG-21. Durability of response to targeted therapies in pediatric low-grade gliomas: A multi-institution retrospective review

Background: The discovery of the driving oncogenic alterations in pediatric low-grade gliomas (pLGGs) has shifted our focus towards management with targeted therapies, especially in relapsing or progressive disease. Limited data is available on the durability of response to targeted therapy in pLGGs once the therapy has ceased. Methods: Multi-institutional retrospective chart review of patients with pLGGs younger than 25 years, between 2010-2021, was undertaken to evaluate the durability of response to targeted therapy and determine risk factors associated with disease progression after cessation of therapy. Results: Current analysis included 18 patients from two centers. Seven (39%) had neurofibromatosis type-1 (NF-1). Diagnoses included: optic pathway glioma (OPG) (6/18, 33%), pilocytic astrocytoma (8/18, 44%), diffuse fibrillary astrocytoma (1/18), ganglioglioma (1/18), glioneural neoplasm (2/18). Sixteen patients received at least one prior line of chemotherapy (range 1-5). Targeted agents included trametinib (50%), selumetinib (5%), binimetinib (22%), vemurafenib (11%) and everolimus (11%). Median time on therapy was 351 days (range 29-979 days). All, but one patient had residual intracranial findings at the end of therapy: eight patients (44%) had stable disease, while ten required additional therapy; 50% were NF-1 patients with OPG. Median time to progression was 203 days (range 29-615 days). Of those who did not require any additional therapies, 50% had suprasellar tumors. Genomic data was available for twelve patients; BRAF-KIAA1549 fusion was the most common genomic alteration. Others included mutations in KRAS, BRAF (V600E), PTPN11, SOX6-RAF1 fusion, NF-1, and a patient with FGFR1, KMT2C, and PTPN11 alterations. Conclusion: Preliminary analysis demonstrates that despite initial response, the majority of patients required additional line of therapy. Patients with NF-1 and OPGs tend to progress after discontinuing therapy, while suprasellar non-NF1 pLGGs tend to develop sustained response to targeted therapies. Additional multi-institutional analysis is underway and will be presented at the meeting.

NFB-03. Neurological manifestations in children and adolescents with Neurofibromatosis type 1 - Implications for management and surveillance

INTRODUCTION: We aimed to (1) characterize the spectrum of clinical phenotypes of NF1 in a random pediatric population, (2) correlate genotype with phenotypic expression for those with a genetic diagnosis, and (3) explore radiological features of NF1 in the central nervous system (CNS) by radiomics analyses to predict clinical course. METHODS: We performed a database search in the hospital information system of the University Children′s Hospital between January 2017 and December 2020 for patients with NF1 and evaluated the clinical phenotype by retrospective chart review. RESULTS: 75 children/adolescents were identified with suspicion/clinical diagnosis of NF1 (median age 10.0 years (range, 1.1-22.6); 35 female), confirmatory revised “diagnostic criteria” were met in 57 patients at the last follow-up. Per number of documented items, major signs were detected as 73/75 café-au-lait macules, 31/63 freckling, 38/71 neurofibromas (thereof 21 plexiform neurofibromas), 18/43 optic pathway glioma, 5/66 Lisch nodules, and two patients with sphenoid dysplasia. Genetic analysis (31/75) identified pathogenic NF1 variants in 27 patients. In 20/66 cases a parent met diagnostic criteria. Cognitive symptoms included developmental delay (28/68), learning deficits (12/48), attention-deficit hyperactivity disorder (3/53), and behavior anomalies (7/63). Classical unidentified bright objects were seen in 29/43, other intracranial tumors in 7/43, and cerebrovascular abnormalities in 5/43. Analysis of imaging features of the CNS in these patients will involve lesion segmentation and radiomics features. Symptomatic/progressive low-grade glioma necessitated neurosurgical resection (4/25) and/or chemotherapy (12/25). In 10/25 neuropsychological functions were assessed by the German neuropsychological basic diagnostic instrument. Until June 30th, 2021, one patient died of progressive plexiform neurofibroma. CONCLUSIONS: A wide range of neurological manifestations, including neuropsychological deficits, should raise the suspicion of NF1 in an unselected pediatric population. We expect imaging features of the CNS to better predict the clinical course and enhance decision-making.

LGG-56. Surgical management of pre-chiasmatic intraorbital optic nerve gliomas in children after loss of visual function – Resection from bulbus to chiasm

INTRODUCTION: Optic pathway gliomas (OPG) in children carry significant morbidity and therapeutic challenges. The subgroup of pre-chiasmatic gliomas manifest with exopthalmus are a subgroup where, after blindness has occurred, an intraorbital and intradural resection is a curative option. We present a two-center cohort using two different surgical approaches and describe indication, technique, and long term surgical outcome. METHODS: A retrospective analysis in both centers was performed to included patients < 18 years at diagnosis with a pre-chiasmatic intra-orbital glioma, in whom a resection from the bulb to the chiasm was performed. RESULTS: 11 patients were included. 4 had NF1. Mean age at surgery was 7.0 years. Interval between diagnosis and surgery was 1-74 (median 10) months. Two had prior chemotherapy, one radiation, one both, one prior intraorbital surgery. In all 5 progression occurred. Indications for surgery were exophthalmos, pain, tumor progression or a combination. 8 patients (Group A) underwent an extradural trans-orbital-roof approach to resect intra-orbital tumour including the optic canal part plus intradural pre-chiasmatic resection. In 3 patients (Group B) a combined supra-orbital mini-craniotomy plus orbital frame osteotomy was used for intraorbital tumour-resection, excluding the optic canal part, plus intradural pre-chiasmatic resection. GTR was achieved in 7/8 of Group A and none had a recurrence (mean-FU 42 month). One residual behind the bulbus showed progression, treated by chemotherapy. All residuals in Group B were remnants of the optic nerve within optic canal remained stable (mean FU 11.8 months). No patient had a chiasmatic functional affection or permanent oculomotor deficits. Two after prior radiotherapy developed slight enophthalmos. CONCLUSION: In these selected patients surgical resection from bulb to chiasm (± removal of optic canal tumor) is safe without long-term sequela and with excellent cosmetic result. Surgery removes immediately exophthalmos and provides an effective long-term tumor control. It should be considered therapy of choice.

NFB-02. Maternal high-fat diet exposure increases the proliferation and glial differentiation of the cells of origin for NF1-optic glioma

Some pediatric cancers arise in the context of tumor predisposition syndromes caused by germline mutations in genes that regulate cell growth. The most common of these syndromes, Neurofibromatosis type 1 (NF1), results in the development of low-grade tumors of the optic pathway (optic pathway gliomas; OPGs) in ~15% of affected children. However, risk assessment for each individual child is difficult, as it is currently challenging to predict which children with NF1 will develop OPG. Emerging human population-based evidence has raised the possibility that patient-specific risk factors, including infant birth weight, may modulate the risk of glioma development. High-infant birth weight can be modeled in mice by maternal exposure to a high-fat high-sucrose (HFHS) diet. To address the hypothesis that maternal high-fat diet exposure will increase the risk of OPG formation through intrinsic effects on the putative tumor cell of origin, we evaluated the effect of maternal exposure to a HFHS diet on the proliferation and differentiation of these cells (neural stem cells within the third ventricular zone; TVZ NSCs). Progeny from obese dams (MatOb) exposed to HFHS diet during and preceding gestation demonstrated increased proliferation and glial differentiation of TVZ NSCs in vivo. Similar results were observed with gestational HFHS diet exposure (GE) that did not result in maternal weight gain, suggesting these effects were related to maternal diet rather than weight. These effects were not observed in NSCs from other regions of the brain, supporting the regional specificity of the effect of diet on these tumor-initiating stem cells. Finally, we found that maternal HFHS diet resulted in elevated levels of leptin and insulin, both of which increase the proliferation of TVZ NSCs. Taken together, these findings provide early experimental evidence that maternal environmental exposure affects developing neural stem cells relevant to the risk of glioma formation.

HGG-24. NTRK-rearranged infantile gliomas of suprasellar/ optic pathway origin

BACKGROUND: Oncogenic fusions involving neurotrophic tyrosine receptor kinase (NTRK) have been identified across cancer types and represent potential therapeutic targets given availability of TRK inhibitors. Gliomas harboring NTRK fusions have been described most commonly in infants with high-grade histology and hemispheric tumor location, though there is emerging evidence suggesting clinical, histopathologic, and molecular heterogeneity. Herein, we present two cases of NTRK-rearranged suprasellar/ optic pathway gliomas. CASE DESCRIPTIONS: The first patient was diagnosed at 6 months old with an extensive suprasellar/ optic pathway tumor, treated with carboplatin/ vincristine, which initially responded but subsequently progressed. A biopsy was then performed, with pathology consistent with infiltrating piloid astrocytoma with anaplastic features (elevated mitoses and Ki-67 index); a BCAN-NTRK1 fusion was identified by RT-PCR and confirmed by Sanger sequencing. After further disease progression on vinblastine monotherapy, this patient began treatment with entrectinib (NCT02650401), with favorable clinical and radiographic responses thus far. The second patient was diagnosed with a large suprasellar/ optic pathway tumor at 3 years old, and underwent upfront partial resection, revealing similar infiltrating piloid/pilocytic astrocytoma with anaplastic features (elevated mitoses and Ki-67 index). A diagnosis of “midline” infantile high-grade glioma (HGG) was also considered, as with the former case. Sequencing demonstrated a SOX10-NTRK3 rearrangement, resulting in an integrated diagnosis of NTRK-fused infantile HGG, for which the patient recently started treatment with larotrectinib (NCT04655404). Both patients’ fusions retain the entire kinase domain of respective NTRK partners, supporting oncogenicity, and neither tumor harbored additional somatic pathogenic variants (both lacked BRAF alterations). Methylation profiling did not confidently classify either tumor. CONCLUSIONS: NTRK-rearranged gliomas may present with primary suprasellar/ optic pathway involvement in infants. Given the potential to offer targeted therapy, testing for the presence of NTRK fusions should be strongly considered for infantile gliomas in any location, including midline, and across the histologic spectrum.

LGG-31. Pediatric low-grade gliomas with FGFR1 mutations and spontaneous hemorrhage: case series

Pediatric low-grade gliomas (pLGG) are the most common pediatric CNS neoplasms. Thanks to the advent of molecular tumor diagnostics, we have begun exploring the clinical relevance of FGFR1 (c.1632C>A; p.N546K) mutations in the pLGG population. However, the risk of spontaneous hemorrhage in pLGG patients harboring FGFR1 mutations is even less understood. We present four pLGG cases with FGFR1 mutation and hemorrhagic episodes. Patient 1 presented with an intraventricular hemorrhage and leptomeningeal disease. Pathology was consistent with suprasellar pilocytic astrocytoma, FGFR1, and PTPN11 mutations. Initial therapy consisted of Carboplatin/Vinblastine per ADVL0515. The patient has had several recurrences, and treatment regimens have included ACNS0223, Everolimus, and A9952 regimen A. Patient 2 was diagnosed with an optic pathway glioma, and pathology confirmed FGFR1, MEK2, PTPN11, and NF1 splice site mutations. The patient also has a history of Noonan’s Syndrome and has undergone several chemotherapy regimens, including A9952 Regimen A, COG MATCH with Erdafitinib, and Avastin. The best tumor response was seen while on Avastin. The patient has presented with two episodes of intratumoral hemorrhage, both after treatment with Avastin. Patient 3 presented with a sudden brain stem hemorrhage and underwent a biopsy and debulking. The pathology was consistent with a pilocytic astrocytoma with an FGFR1 mutation confirmed by Next-generation sequencing (NGS). Treatment regimens for this patient include A9952 Regimen A and Vinblastine. Patient 4 presented with acute headache and vomiting and was found to have a hemorrhagic suprasellar mass. The patient underwent tumor debulking, and pathology was consistent with low-grade glioma. NGS revealed FGFR1 and KRAS mutations. The patient received therapy as per A9952 Regimen A. Greater surveillance of this molecular and clinical finding is warranted to uncover the association between FGFR1 mutations and hemorrhage in patients with low-grade gliomas.

NFB-23. Extent of tumor but not location may be predictive of longitudinal disease severity in children with NF1-associated gliomas requiring treatment

BACKGROUND: Children with Neurofibromatosis Type 1 (NF1) are at risk for developing gliomas in multiple locations, particularly the optic pathway and brainstem. The goal of this study is to determine if glioma location in NF1 impacts tumor progression and accumulation of neurological deficits over time. METHODS: Retrospective chart review of 98 pediatric patients with NF1-associated gliomas between 1999-2021 at St. Louis Children’s Hospital. Patients who had never received treatment were excluded from analysis. Each glioma was categorized into one of four locations: posterior fossa (PF, n=12, 21%), supratentorial midline (SM, n=33, 57%) supratentorial cortical (SC, n=4, 7%), brainstem (BS, n=9, 15%). Patients with gliomas in different locations had each tumor counted separately (58 total gliomas analyzed). RESULTS: No SC tumors progressed. Time to first progression was comparable across the other 3 locations, and there was no meaningful different in neurologic deficits over time by tumor location. The majority of patients who demonstrated three or more clinical or radiographic progressions had tumors in the SM region. Within the SM tumor group, each tumor was further characterized as a deep extensive glioma (DEG; 36%) or an optic pathway glioma without deep extension (nonDEG; 64%). DEG had a slightly higher number of neurological deficits at baseline (DEG 2.08, nonDEG 1.19), fewer patients with no neurologic deficits (8.3% DEG vs 28.6% nonDEG) and a higher proportion of patients with a first progression event (41% DEG vs 24% nonDEG). However, DEG and nonDEG had similar risk of subsequent progressions after the initial event. CONCLUSION: Among children with NF1 who required glioma treatment, location was not a significant predictor of multiple progression or neurologic morbidity over time. Within the SM location, DEGs represent a newly characterized group that exhibit potentially higher rates of progression and neurological deficits. Multi-institutional analysis is needed to confirm these findings.

LGG-29. Use of Bevacizumab in Pediatric Low-grade Glioma: Ten-year experience in a single center

PURPOSE: Pediatric low-grade gliomas (PLGG) have excellent overall survival but frequently need non-surgical therapy at diagnosis or after progression at unresectable sites such as the optic pathway. Chemotherapy side effects have led to the need for better-tolerated regimens with a sustained response. Bevacizumab, a humanized anti-VEGF monoclonal antibody has been used in monotherapy and/or in combination for these entities. Here we present our experience with its use in PLGG. METHODS: A retrospective, observational, single-institution study between 2008-2018 was performed, reporting the short-term outcomes of safety and efficacy of bevacizumab in progressive PLGG. RESULTS: Twenty-six patients with a median age at diagnosis of 3.32 years old [0.12-14.7] and the median age at the treatment of 8.11 years old [0.41-16.82] were included in the study. Nineteen had optic pathway gliomas and chiasmatic-hypothalamic gliomas (73.1%), 9 of them (47.4%) associated with neurofibromatosis type 1 (NF1). Fourteen non-NF1 tumors were molecularly studied, disclosing BRAF-KIAA1549 fusion transcript in 9 and BRAF V600E mutation in 2. Bevacizumab was administered in combination with other agent(s) in 16 of the 35 treatment courses. Responses were assessed at 3, 6, 12 months, and at the end of treatment. Progression-free survival at 12 months was 94%, and no severe adverse events were observed. CONCLUSIONS: In our series, Bevacizumab in PLGG showed short-term clinical efficacy with a favorable toxicity profile. Larger and long-term prospective studies may determine whether the response is conditioned upon different clinical or molecular features.

LGG-33. A 40-year cohort study of evolving hypothalamic dysfunction in 90 infants and young children (&amp;lt;3y) with optic pathway gliomas

BACKGROUND: Despite high survival, paediatric optic pathway hypothalamic gliomas are associated with significant morbidity and late mortality. Those youngest at presentation have the worst outcomes. METHODS: We aimed to assess presenting disease, tumour location and treatment factors implicated in the evolution of neuroendocrine, metabolic and neuro-behavioural morbidity in children diagnosed before their 3rd birthday and followed over four decades (1981- 2020). RESULTS: Ninety infants/young children followed-up for 9.5 years (range 0.5-25.0) were included in the study. Fifty-two (57.8%) patients experienced endo-metabolic dysfunction (EMD), the large majority (46) had hypothalamic involvement (H+) and lower endocrine event free survival (EEFS) rates. Median time to first endocrine event was 3.4 years, with EEFS declining up to 13.6 years after diagnosis. EMD was greatly increased by a diencephalic syndrome presentation (85.2% vs 46%, p=0.001), H+ (OR 6.1 95% CI 1.7 – 21.7, p 0.005), radiotherapy (OR 16.2, 95% CI 1.7 – 158.6, p=0.017) and surgery (OR 4.8 95% CI 1.3- 17.2, p=0.015), all associated with anterior pituitary disorders. Obesity occurred in 25% of cases and clustered with the endocrinopathies. Posterior pituitary disorders were recorded in 15 subjects (16.7%), only after surgery and/or as a consequence of hydrocephalus in those with suprasellar tumours and hypothalamic disease. Neuro-behavioural deficits occurred in over half (52) of the cohort and were associated with H+ (OR 2.5 95% C.I. 1.1 – 5.9, p=0.043) and radiotherapy (OR 23.1 C.I. 2.9 – 182, p=0.003). CONCLUSIONS: Very young children with OPHG carry a high risk of endo-metabolic and neuro-behavioural comorbidities which deserve better understanding and timely/parallel support from diagnosis to improve outcomes. These evolve in a complex hierarchical pattern overtime whose aetiology appears predominantly determined by injury from the hypothalamic tumour location alongside adjuvant treatment strategies.

LGG-43. Reduction in the cerebrospinal fluid protein level after bevacizumab treatment in patients with optic pathway low-grade gliomas

Cases Presentations: Case 1: A 1-year-old boy with suprasellar pilocytic astrocytoma with previous history of shunting disfunction, treatment according vinblastine protocol due to anaphylactic reaction with carboplatin presented with ascites and necessity of ventricular-atrial shunt. Due to high protein cerebrospinal fluid (CSF) level (551mg/dl) he was submitted to external ventricular drainage and bevacizumab 10mg/kg was associated to his oncology treatment. After three cycles of bevacizumab, the patients’ CSF protein levels decreased dramatically 178 mg/dL, allowing the shunt procedure without complications and shorter hospital stay. Case 2: A ten-year-old boy with suprasellar pilocytic astrocytoma treated with three lines of chemotherapy showed tumor progression one year after the end of carboplatin-vincristine protocol and shunting disfunction. External ventricular drainage was performed, and the CSF showed 590mg/dl protein level. He was treated with vinblastine 6mg/m2 weekly and bevacizumab 10mg/kg each 14 days. After two cycles of bevacizumab, the protein level was 191mg/dl allowing another V-P shunt procedure. Discussion: Optic pathway gliomas frequently cause elevated cerebrospinal fluid protein concentrations leading to shunts occlusions and failures, necessity of external ventricular drainage and longtime hospitalization, implicating risk of serious infections. Bevacizumab is a monoclonal antibody with immunomodulatory and anti-vascular endothelial growth factor (VEGF) activities that has been used in combination with other chemotherapeutic agents such as irinotecan and vinblastine to treat low-grade gliomas and has been reported to decrease the CSF protein concentration.Final Comments: Bevacizumab treatment in patients with gliomas and high CSF protein levels seems effective in decreasing protein leakage from the vessels to the ventricles, thereby improving the scope for successful shunt placement.