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Background EORTC study 22033–26033 showed no difference in progression-free survival between high-risk low-grade glioma receiving either radiotherapy (RT) or temozolomide (TMZ) chemotherapy alone as primary treatment. Considering the potential long-term deleterious impact of RT on memory functioning, this study aims to determine whether TMZ is associated with less impaired memory functioning. Methods Using the Visual Verbal Learning Test (VVLT), memory functioning was evaluated at baseline and subsequently every 6 months. Minimal compliance for statistical analyses was set at 60%. Conventional indices of memory performance (VVLT Immediate Recall, Total Recall, Learning Capacity, and Delayed Recall) were used as outcome measures. Using a mixed linear model, memory functioning was compared between treatment arms and over time. Results Neuropsychological assessment was performed in 98 patients (53 RT, 46 TMZ). At 12 months, compliance had dropped to 66%, restricting analyses to baseline, 6 months, and 12 months. At baseline, patients in either treatment arm did not differ in memory functioning, sex, age, or educational level. Over time, patients in both arms showed improvement in Immediate Recall (P = 0.017) and total number of words recalled (Total Recall; P < 0.001, albeit with delayed improvement in RT patients (group by time; P = 0.011). Memory functioning was not associated with RT gross, clinical, or planned target volumes. Conclusion In patients with high-risk low-grade glioma there is no indication that in the first year after treatment, RT has a deleterious effect on memory function compared with TMZ chemotherapy.

Tumor infiltrating lymphocytes (TILs) and programmed death ligand 1 (PD-L1) are targets of immune checkpoint inhibitors. Forty-three World Health Organization (WHO) grade II/III gliomas (39 IDH-mutant [mut], 4 IDH-wildtype [wt]) and 14 IDH-mut glioblastomas (GBM) were analyzed for TIL (CD3+; PD1+) infiltration and PD-L1 expression. Results were compared with the data of a previously published series of 117 IDH-wt glioblastomas. PD-L1 gene expression levels were evaluated in 677 diffuse gliomas grades II-IV from The Cancer Genome Atlas (TCGA) database. TIL and PD-L1 expression were observed in approximately half of WHO grade II/III gliomas. IDH-wt status was associated with significantly higher TIL infiltration and PD-L1 expression among all (grades II-IV) cases (n = 174, P < 0.001) and within the cohort of glioblastomas (n = 131, P < 0.001). In low-grade glioma (LGG) and glioblastoma cohorts of TCGA, significantly higher PD-L1 gene expression levels were evident in IDH-wt compared with IDH-mut samples (LGG: N = 516; P = 1.933e-11, GBM: N = 161; P < 0.009). Lower PD-L1 gene expression was associated with increased promoter methylation (Spearman correlation coefficient -0.36; P < 0.01) in the LGG cohort of TCGA. IDH-mut gliomas had higher PD-L1 gene promoter methylation levels than IDH-wt gliomas (P < 0.01). The immunological tumor microenvironment of diffuse gliomas differs in association with IDH mutation status. IDH-wt gliomas display a more prominent TIL infiltration and higher PD-L1 expression than IDH-mut cases. Mechanistically this may be at least in part due to differential PD-L1 gene promoter methylation levels. Our findings may be relevant for immune modulatory treatment strategies in glioma patients.

PURPOSE Primary spinal low-grade gliomas (LGGs) are rare, can be difficult to treat, and can result in significant morbidity. The management of pediatric spinal LGGs remains controversial. METHODS A national multi-centre retrospective review of spinal LGGs diagnosed in children less than 18 years of age between 1990–2015 was undertaken to examine the clinical features, pathological subtypes, and treatment outcomes. RESULTS Forty-three patients from five institutions were included. The median age of diagnosis was 5.2 years. All patients were symptomatic at diagnosis. Forty-four percent of patients were diagnosed at least 6 months after symptoms developed. Two patients had metastatic disease at diagnosis. The most common histology was pilocytic astrocytoma (48.8%). Molecular information was available for 15/43 patients: 6 patients had BRAF fusions and 4 patients had BRAF V600E mutations. Gross-total resection was achievable in only 6 patients. Twenty-seven patients were treated with surgery-only and the others received chemotherapy and/or focal radiation. Eleven patients were irradiated. No patients were registered in clinical trials for first-line therapy. Twenty-three patients experienced relapse or progression. Patients were followed for a median of 8.3 years (range, 0.5–20.4 years). Five-year progression-free survival (PFS) and overall survival (OS) rates were 48.3% (95% CI, 32.3% to 62.5%) and 89.7% (95% CI, 74.6% to 96.1%) respectively. CONCLUSION There is significant heterogeneity in surgical outcomes and treatment modalities of pediatric spinal LGGs. The PFS and OS rates remain suboptimal, likely due to tumor location. The low clinical trial enrollment rate highlights the paucity of available trials for spinal LGGs.

In-operable low grade gliomas (LGG) in the pediatric population continue to present a treatment dilemma. Due to the low-grade nature of these tumors, and variable response to chemotherapy / radiation, the choice of adjuvant treatment is difficult. Overall survival is directly related to the degree of surgical resection, adding complexity to these inoperable tumors. Current chemotherapeutic regimen for these inoperable tumors includes vincristine (VCR) and carboplatin (Carbo). With advancements in the molecular characterization of gliomas, the role of targeted therapy has come into question. We present a 2-year-old female with biopsy proven Pilocytic Astrocytoma (positive BRAF-V600E mutation) involving the hypothalamic/optic chiasm region. She presented with ataxic gait, bi-temporal hemianopia, obstructive hydrocephalus and central hypothyroidism, which progressed to altered consciousness, and right hemiparesis due to location/mass effect of the tumor. She was initially treated with chemotherapy (VCR/Carbo) but her tumor progressed at 6 weeks of treatment. As her tumor was positive for BRAF-V600E mutation, she was started on Dabrafenib monotherapy, resulting in dramatic improvement in her clinical symptoms (able to stand, improved vision), and a 60% reduction in tumor size at 3-months. At 6-months, follow up MRI showed slight increase in the solid portion of the tumor, with no clinical symptoms. We plan to add MEK inhibitor (Trametinib) and continue with Dabrafenib. Our experience and literature review suggests that LGG with BRAF-V600E mutations may benefit from upfront targeted therapy. Prospective clinical trials comparing the efficacy of BRAF inhibitors versus standard chemotherapy in LGG with BRAF mutations are urgently needed.

Molecular diagnosis in brain tumors has been widely spread after the publication of WHO 2016 classification. But it become a major problem that there are some tumors not to be classified on its criteria, especially in pediatric neuroepithelial tumors. To clarify the characteristics of gliomas in pediatric and adolescent and young adult age (AYA), we picked up 131 neuroepithelial tumors under 30-year-old at Kyoto University and analyze their molecular profiles. Hot spot mutations in IDH1/2, H3F3A, HIST1H3B, TERT promoter, and BRAF were analyzed by Sanger sequencing, and 1p/19q codeletion was examined by FISH or MLPA. With the pathohistological diagnosis and genetic information, all tumors were classified based on WHO 2016 classification. The terms “not otherwise specified” (NOS) and “not elsewhere classified” (NEC) were used based on cIMPACT-NOW. There were 25 glioblastomas and 34 pilocytic astrocytomas, which accounted for a larger percentage than in adult tumors. IDH-wild type gliomas accounted for 55% in diffuse astrocytomas and 69% in anaplastic astrocytomas. The percentages of gliomas with NEC were 50% of oligodendrogliomas and 20% in anaplastic oligodendrogliomas, respectively. Most pilocytic astrocytomas were under 20-year-old (27 patients) and located in infratentorial area (21 patients). Based on WHO 2016 classification, not a few neuroepithelial tumors in pediatric and AYA ages could be classified clearly. These tumors had more different genetic abnormalities than those in adult. Therefore, it may be important to evaluate these tumors with comprehensive genetic analysis.

Isomorphic diffuse glioma (IDG) was first described in 2004 as an epilepsy-associated supratentorial diffuse glioma with low cellularity, low proliferation and very monomorphic tumour cells. Most patients had seizures since childhood but were operated on as adults. To study the position of these lesions among brain tumours we histologically, molecularly and clinically analysed 26 histologically typical IDGs. Tumour cells were GFAP-positive, MAP2-, OLIG2- and CD34-negative and the nuclear ATRX-expression was retained. Proliferation was very low. Sequencing of 24 cases revealed an IDH-wildtype status. Cluster analyses of DNA methylation data showed that IDG has a DNA methylation profile distinct from those of different glial/glio-neuronal brain tumours and normal hemispheric tissue. About half of IDGs had copy number alterations of MYBL1 or MYB (13/25) and half of the cases analysed by RNA-sequencing had gene fusions of MYBL1 or MYB with various gene partners (11/22), often associated with an increased RNA-expression of the respective MYB-family gene. Integrating all data available, 77% of IDGs had either MYBL1 (54%) or MYB (23%) alterations. All patients had a good outcome and most were seizure-free after surgery. In summary, we show that isomorphic diffuse glioma is a distinct benign tumour in the family of MYB/MYBL1-altered gliomas. DNA methylation analysis is very helpful for their identification. More recent analyses of a large cohort of MYB/MYBL1-altered brain tumours suggest the presence of a third methylation group that primarily contains paediatric cases and seems to be distinct from IDG and angiocentric gliomas. Further histological, molecular and clinical analyses are ongoing.

Pediatric low-grade gliomas (pLGG) are primarily driven by genetic alterations in the RAS/MAPK pathway, most commonly involving BRAF of NF1. Despite their molecular convergence, pLGG often show unexplained variability in their clinical outcome. To address this, we molecularly characterized a cohort of >1,000 clinically annotated pLGG. 84% of cases harbored a detectable driver mutation. The remaining 16% of patients nonetheless showed RAS/MAPK pathway up-regulation at the RNA level. The clinical presentation and outcome of pLGG appeared highly variable and linked to the alteration type: re-arrangement or SNV. Re-arrangement-driven tumors were diagnosed at a younger age (6.6 versus 10.9 years, p

Pediatric Low-grade gliomas (PLGGs) are extremely heterogeneous tumors and account for approximately 35% of childhood brain tumors. This retrospective study on 55 newly diagnosed children (

BACKGROUND Numerous variant BRAF genetic alterations have been associated with malignancies. BRAF activating fusions/mutations are frequently present in low grade gliomas. BRAF intragenic deletions have been reported in melanoma, but have not previously been reported in gliomas. OBJECTIVE To report a BRAF intragenic deletion in a pediatric patient with recurrent low-grade glioma. RESULTS A 3-year-old female underwent a complete resection of a posterior fossa pilocytic astrocytoma. She had recurrences at age 4, and then at age 9; pathology was consistent with pilocytic astrocytoma. Microarray analysis on sample from the first recurrence showed one region of loss encompassing 86 Kbp within the BRAF gene. The deletion breakpoints are within intron 1 and 9, resulting in loss of exons 2 through 9, inclusive. This has been previously described melanoma, but appears to be a novel finding in glioma. It is hypothesized that, since the loss retains the kinase and ATP binding pocket domains but deletes the N-terminal conserved region 1 and 2 (CR1, CR2) of the BRAF gene, it is likely functionally similar to the loss and activation resulting from the more usually described KIAA1549 and BRAF gene fusion. CONCLUSION This is the first BRAF intragenic deletion involving exons 2–9 reported in a glioma. Although 86kbp is small using whole genome microarray technology, it is large using sequencing strategies, and a targeted sequencing approach to investigate the BRAF gene would not readily identify this deletion. It is speculated that the deletion may be under ascertained in the pediatric population.

PURPOSE Pilomyxoid astrocytomas are predominantly located in supra-chiasmatic region and are more clinically aggressive than pilocytic astrocytomas, although recent WHO 2016 classification placed them into the grade I/II category. In our study, we describe imaging correlation of PMA to their genetic signature. MATERIALS AND METHODS We identified 12 pediatric patients with pathologically proven PMA, PA, and PA with myxoid features in an IRB approved study. Three of the tumors had whole exome somatic and germline sequencing. Qualitative MRI characteristics of location, size, enhancement, edema, T2 and T1 intensity, and multifocality were assessed. RESULTS Among the PMA, 3 cases were found to have KIAA1549-BRAF fusion, 1 case BRAF V600E mutation, and 2 cases had wildtype BRAF. The BRAF wildtype tumors had atypical imaging features with intraventricular extension of tumor, involvement of frontal lobe parenchyma and one tumor demonstrating increase in size and development of enhancement at 5 years. Whole exome sequencing of BRAF wildtype tumors identified somatic truncation mutations in NF1 R1534X and R1513X with wildtype germline NF1 and missense mutations in KMT2C and GLTSCR1. Among PAM, one was BRAF wildtype with mutations i PTCH1 M956V and PTPN1 (A72V) and demonstrated atypical features of intratumoral hemorrhage on presentation. Among PA, one was positive for KIAA1549-BRAF, one was BRAF wildtype. CONCLUSIONS BRAF wildtype PMA and PA demonstrate atypical tumor localization and are associated with atypical genetic mutations on whole exome sequencing. On the contrary, presence of KIAA1549-BRAF fusion or BRAF V600E mutation within PMA and PA correlates with classic qualitative imaging characteristics.

INTRODUCTION The incidence of IDH mutations in pediatric glioma is unclear. Recent publications suggest rates ranging between 0–20%. Therapy poses challenges as it is unclear if the biology and prognosis of pediatric IDH-mutant gliomas are identical to adults. METHODS We performed an IRB approved, systematic retrospective search for IDH-mutant gliomas in the Dana-Farber Cancer Institute/Boston Children’s Hospital database between 2009–2018, analyzing incidence, demographics, histology, co-occurring genetic alterations and outcome. RESULTS We identified 575 patients with glioma, ages 0–21 years. Of these, 394 underwent biopsy/resection (0–9 years:n=204; 10–21 years:n=190), with 294 genetic testing. Fifteen of 294 tumors (5%) were IDH1-mutant. Among patients 0–9 years and 10–21 years, 1/156 (0.6%) and 14/138 (10%) had IDH1-mutant tumors, respectively. Among patients 10–21 year old, 13/115 low-grade gliomas were IDH1-mutant (11%). High-grade gliomas accounted for the remaining 23, with one IDH1-mutant glioma (4%). Most common co-occurring genetic alterations for diffuse astrocytoma (n=12) were TP53 (n=9) and ATRX (n=2). Three patients with IDH1-mutant oligodendrogliomas had 1p/19q deletion. Eleven IDH1-mutant patients were evaluable for outcomes with median follow-up of five years. Five-year radiation-free, progression-free and overall survival for patients with low-grade histology were 76% and 100%, respectively. One patient with high-grade glioma recurred 1.2 years after upfront chemo-radiation and died soon after recurrence. CONCLUSION IDH-mutant gliomas comprise a small proportion of pediatric gliomas. Incidence rate is higher in the second decade of life. Comparative analyses between pediatric IDH-mutant gliomas and adult historical cohorts are currently underway, evaluating outcomes, radiation therapy and frequency of malignant transformation.

BACKGROUND Heterogeneous pathology in hemispheric low-grade gliomas (hemLGG) stress the importance of molecular testing in terms of prognosis prediction and targeted therapy options. METHODS Demographic data was collected and targeted genomic approach was employed in the single institutional study. RT-PCR was used to screen for KIAA1549-BRAF fusion and FGFR1 tyrosine-kinase domain duplication (FGFR1-ITD). Direct sequencing evaluated point mutations (BRAF ex15 and ex11, FGFR1 ex12 and ex14). Samples with no detected alteration were subjected to panel RNA-sequencing (FusionPlex Archer Diagnostics). RESULTS Within 2000–2019 were diagnosed 76 patients with hemLGG (median age 11.1y, range 0.0y–18.5y) comprising predominantly of ganglioglioma, dysembryoplastic neuroepithelial tumors, and diffuse astrocytoma. 40 % of hemLGG were characterized by BRAF alterations with over 2/3 of those cases harboring BRAF point mutations (two BRAFex11, 12 BRAFV600E). Notably, BRAF fusions were uncommon and detected only in six patients (two KIAA-BRAF fusion, two minor oncogenic BRAF variants, two non-KIAA BRAF fusion). 25 % of alterations were found in genes for receptor tyrosine kinases, consisting of seven patients with FGFR1-ITD, three FGFR2/3 fusions, two FGFR1 mutations, two ALK fusions, and one ROS fusion. Out of MAP kinase pathway, the most frequent alteration was IDH1 mutations (n=9). Two angiocentric gliomas were characterized by MYB-QKI fusion. CONCLUSION Targeted sequencing combined with RNA-sequencing is feasible to establish molecular diagnosis in majority of cases and reveal new and rare alterations. Significant prevalence of non-BRAF alterations explains heterogeneity among hemLGG.

Microvascular proliferation (MVP), an aberrant vascular structure is a histopathological hallmark of glioblastoma multiforme (GBM). Although MVP tends to be associated with high-grade glioma, it has also been detected in WHO grade I pilocytic astrocytoma (PA). However, little is known about the mechanism underlying its formation. Using TP53 point mutations as a marker for tumor-derived cells, we earlier reported that MVP was partially converted from tumor cells via mesenchymal transition. In the current study we used the KIAA1549-BRAF fusion gene as a marker to assess whether MVPs in PA contained tumor-derived cells and/or phenotypically distinct tumor cells expressing vascular markers. Samples from three PA patients harbored the KIAA1549 exon 15, BRAF exon 9 fusion gene. In two patient samples with abundant MVP, RT-PCR assay detected strong bands arising from the KIAA1549-BRAF fusion gene in both tumor cells and cellular components of MVP. Digital PCR showed that vis-à-vis tumor tissue, its relative expression in cellular components of MVP was 42% in one- and 76% in another sample. FISH revealed amplified signals in both tumor cells and cellular components of MVP indicative of tandem duplication. Our findings suggest that in patients with PA, some cellular components of MVP contained tumor derived cell and/or phenotypically distinct tumor cells expressing vascular markers.

IDH-mutant astrocytomas are well-recognized in the adult population and while increasingly identified, are rare in children and young adults. These tumors typically arise in cortical locations, however cases of these tumors occurring in the brainstem have been reported in the adult literature. Here we present two cases of young adults with IDH-mutant astrocytomas of the brainstem. Patient 1 was initially diagnosed with an infiltrative low grade glioma (LGG) of the brainstem at 19 years of age based on conventional magnetic resonance imaging and magnetic resonance spectroscopy characteristics. She was treated with LGG therapy and had stable disease for over three years. At the time of disease progression she underwent biopsy and pathology was consistent with an anaplastic astrocytoma, IDH1 R132S mutant. Despite treatment she experienced rapid disease progression and died six months later. Patient 2 is a 17-year-old male who underwent up-front biopsy of an infiltrating brainstem lesion; pathology was consistent with diffuse astrocytoma, IDH1 R132H mutant. He was treated with focal irradiation and chemotherapy and continues to have stable disease 26 months post diagnosis. To our knowledge, this is the first report of IDH-mutant astrocytomas occurring the brainstem in young adult patients. Both patients’ tumors harbored accompanying TP53 mutations, but not ATRX mutations. These two cases reveal the importance of obtaining biopsies for brainstem tumors to perform molecular characterization and appropriate prognostication.

The patient was a 17-year-old boy with a history of 4 non-febrile convulsions at 15 and 16 years of age. He visited the Department of Pediatrics at a pediatric hospital. An electroencephalogram showed right frontal spike discharge. MRI was performed and judged to show no abnormality. The pediatric doctor diagnosed him with epilepsy. At 17 years old, he was referred to our Department of Adult Neurosurgery for transition. Physical and neurological examinations showed no abnormalities. Brain MRI showed right frontal cortical small tumor, with T1 low, T2 high, diffusion-weighted imaging low, and partial contrast enhancement. We diagnosed him with a brain tumor and symptomatic epilepsy. We surgically removed a right frontal cortical tumor. A pathological examination finalized the diagnosis of dysembryoplastic neuroepithelial tumor. MRI confirmed the total removal of the tumor. Anticonvulsant was started before surgery. No epileptic seizure was observed, so the anticonvulsant medication was gradually tapered and stopped at two years after the surgery. No epilepsy nor recurrence has been observed thus far. The problem with the initial management of this case at the Department of Pediatrics in the pediatric hospital was that the brain tumor was missed despite an MRI examination. Had the transition not happened, this brain tumor might not have been diagnosed. A brain tumor is a rare disease, and epilepsy is a common disease. However, in cases of non-febrile convulsion, a brain tumor should be considered. Collaboration within a single department, hospital and local area should be established.

AIM Recurrent structural variants involving MYB and MYBL1 transcription factors were recently identified in pediatric low-grade gliomas (pLGGs), such as the MYB-QKI rearrangement in Angiocentric Gliomas and truncations of MYBL1 (MYBL1tr) in Diffuse Astrocytomas. However, therapeutic dependencies induced by these alterations remain unexplored. METHODOLOGY We have generated in vitro pLGG mouse neural stem cell (NSCs) models engineered to harbor distinct MYB/MYBL1 genomic alterations. We used single cell RNA sequencing approaches to determine the transcriptional profile and dissect the central regulatory networks of our in vitro pLGG models over time. To identify specific genetic dependencies associated with MYB/MYBL1 mutations, we employed the Brie genome-wide mouse CRISPR lentiviral knockout pooled library, consisting of 78,637 single guide RNAs (sgRNAs) targeting 19,674 mouse genes. RESULTS MYB/MYBL1 expression in neural stem cells induced activation of cell-cycle related, glioma-related and senescence-related pathways that are involved in normal development, including activation of MAPK and mTOR signaling which are also activated in human pLGG samples. Genome-scale CRISPR-cas9 screens in isogenic NSCs expressing MYB-QKI or MYBL1tr identified differential genetic dependencies relative to GFP controls. These included regulators of cell-cycle progression and several modulators of the ubiquitin-proteasome degradation pathway. Analysis of RNA-sequencing data from human tumors revealed several of these dependencies identified in the cell line model to be differentially expressed in MYB-altered pLGG tumors relative to normal brain. CONCLUSION Expression of MYB family alterations induces expression of key developmental and oncogenic pathways and genetic dependencies that represent potential therapeutic targets for MYB or MYBL1 rearranged pLGGs.

Gliomas in children are rarer than in adult, then treatment strategies might vary from facility to facility. We report clinical features and outcome of pediatric glioma in our institution. Twenty-nine patients diagnosed with glioma, exclude ependymoma, 14 boys and 15 girls, among 98 pediatric brain tumor patients treated at Kagoshima University Hospital since 2006 were reviewed histopathology, extent of resection, adjuvant therapy and outcome, etc. Mean age at surgery was 10.4 (S.D. 5.6) years. Median follow-up period was 19.1 months. Histopathological diagnosis comprised 8 pilocytic astrocytoma, 3 ganglioglioma, 2 subependymal giant cell astrocytoma, 5 WHO grade Ⅱ astrocytoma, 8 glioblastoma, and desmoplastic infantile astrocytoma, anaplastic astrocytoma and astroblastoma were one case each. Tumor resection was performed in 24 cases, and 5 cases underwent biopsy. Chemotherapy was performed in 15 cases and irradiation was performed in 9 cases. Out of 5 WHO grade Ⅱ astrocytoma cases, 2 cases underwent biopsy following chemotherapy, 1 case underwent biopsy only and other 1 case underwent total resection. The four cases show long survival ranged from 71 to 136 months without irradiation. All of eight glioblastoma cases show poor prognosis ranged from 8.6 to 26.7 months regardless of chemo-radiotherapy. In management for pediatric brain tumor patients, irradiation is often laid over until recurrence. In WHO grade Ⅱ astrocytoma, the treatment strategy might be reasonable using appropriate chemotherapy even though biopsy cases.

OBJECTIVE In this case report, we present a pediatric patient with gross hematuria and hydroureteronephrosis associated with high dose carboplatin. Given the paucity of literature on the subject, we also conduct and present a review of cases. CASE PRESENTATION: A 6-year-old Caucasian female with history of Type 1 neurofibromatosis was undergoing treatment for a low-grade glioma with monthly high dose carboplatin (560 mg/m2). After 8th dose out of 13, the patient developed severe nausea and vomiting and was admitted for dehydration. She was noted to have microscopic hematuria. After 9th dose, the patient again developed severe nausea, vomiting and gross hematuria with clots. She was admitted and treated with IV hydration. Renal ultrasound showed newly developed bilateral hydroureteronephrosis. Coagulation studies were normal. Multiple cultures and viral studies were negative. Hematuria cleared spontaneously after 4 days of aggressive hydration. RESULTS Subsequent carboplatin was given with aggressive hydration and minimized nausea/vomiting and no hematuria was observed. Literature review revealed only 4 reported cases of carboplatin-induced hematuria, including only one pediatric case that occurred in a patient with concurrent thrombocytopenia. Carboplatin may exhibit toxicity to the transitional epithelial cells of the urogenital tract causing hemorrhage from the renal pelvis and ureters. If untreated, this may lead to urinary outflow obstruction and subsequent obstructive nephropathy. CONCLUSION We present a rare toxicity, gross hematuria caused by high-dose carboplatin treatment. Providers should be aware of this rare toxicity and provide timely hydration and supportive care to prevent development of obstructive kidney injury and/or renal failure.

Pilocytic astrocytomas (PA) are low-grade gliomas (pLGG) and are the most frequent childhood brain tumors. They are characterized by oncogene-induced senescence (OIS) initiated and sustained by senescence-associated secretory phenotype (SASP) factors. OIS and SASP in PA are thought to be driven by aberrations of the mitogen-activated protein kinase (MAPK) pathway (e.g. KIAA1549:BRAF fusion, BRAFV600E mutation, for the most common MAPK alterations occuring in PA), leading to its sustained activation. The MAPK pathway cascade is activated in a sequential manner: 1) ERK activation, which phosphorylates downstream partners in both cytoplasm and nucleus. 2) ERK-mediated induction of immediate early genes encoding transcription factors. 3) Induction of MAPK target genes expression. 4) Activation of downstream pathways. Our aim is to unravel the molecular partners involved at each level of the sustained MAPK pathway activation in pLGG with different genetic backgrounds (KIAA1549:BRAF fusion and BRAFV600E mutation), and leading to the induction of OIS and SASP factors expression. pLGG cell lines DKFZ-BT66 (KIAA1549:BRAF) and BT-40 (BRAFV600E) were treated with the MEK inhibitor trametinib at key time points, and gene expression profile analysis was performed, allowing transcriptome analysis at each step of the MAPK cascade. This will be combined with a whole proteomic and phospho-proteomic analysis. Combination of the transcriptome and proteome data layers will allow the identification of a) downstream targetable partners activated by the MAPK pathway involved in PA senescence, b) new putative targets that might bring benefit in combination with MAPK inhibitors.

OBJECTIVE The natural course of incidentally discovered small intracranial lesions has not been well discussed. Surgical intervention, including resection and biopsy, could be achieved if the lesion is growing. We present 13 cases with incidentally found, small non-enhancing lesions without related symptoms. METHODS We retrospectively reviewed a series of 13 children with T1 hypointense and T2 hyperintense intracranial lesions less than 20 mm in diameter without enhancement. We excluded the patients with NF-1 or Tuberous sclerosis. RESULTS Most patients underwent MRI for headache unrelated to the lesions. All cases were located supratentorially. The median age of the patients at the initial examination was 8.9 years (range, 2.2–14.6). Of these children, 2 patients (15.3%) underwent surgery because of progression on follow-up MR images. The pathological diagnosis was compatible with diffuse astrocytoma. Patients were followed for a median of 55 months (range, 11–87) and the overall survival rate was 100%. No patient experienced increase in size after 3 years of follow-up. CONCLUSIONS In most patients with small intracranial lesions, the lesions remained stable and conservative management was appropriate. However, in a few cases, the lesions changed in size or quality and surgical intervention was necessary. Long-term follow-up at least 3 years is mandatory.

Desmoplastic infantile astrocytoma (DIA) and desmoplastic infantile ganglioglioma (DIG) are benign glioneuronal tumors that typically occur in infants, involve the superficial cerebral cortex, and have an excellent prognosis. DIA/DIG are a distinct molecular entity based on DNA methylation profiling. BRAF600 mutations are frequently reported in DIG/DIA. A recent comprehensive genetic analysis of infantile hemispheric gliomas identified 2 unique groups: group 1 harbored alterations in the receptor tyrosine kinase (RTK) genes ALK, ROS1, NTRK, and MET and group 2 harbored alterations in the RAS/MAPK pathway. We report a case of a 6.5-year-old girl who presented with seizures and right homonymous hemianopia. MRI of her brain demonstrated a large cystic/solid left hemispheric mass with remodelling of the overlying skull, consistent with a long-standing process. She underwent a gross total resection (GTR) and pathology demonstrated a DIG with a PPP1CB-ALK gene fusion (exon 5 to exon 20) identified by RNA sequencing. She remains disease free 12 months following GTR. A literature review identified 4 reported cases of pediatric brain tumors with PPP1CB-ALK gene fusions including: a 3-month-old with a hemispheric high-grade glioma which recurred 4 years later and pathology showed mature ganglioglioma, with both tumors showing the identical PPP1CB-ALK gene fusion; a 10-month-old infant with a hemispheric low-grade glioma; an infant with a “congenital” hemispheric high-grade glioma; and a child with an astrocytoma with no further clinical data. PPP1CB-ALK gene fusion appears to be a rare oncogenic driver in gliomas of infancy, including DIG.

The PBTC conducted a re-treatment study (NCT01089101) evaluating selumetinib (AZD6244, ARRY-142886), a MEK I/II inhibitor, in children with recurrent/progressive pLGG. Eligible patients must have previously enrolled on PBTC-029 or PBTC-029B and progressed after coming off treatment with selumetinib. Patients must have maintained stable disease (SD) for ≥12 courses or had a sustained radiographic response (partial or complete) during their first exposure to selumetinib. Thirty-five eligible patients (median age: 13.11 years [range 7.96–25.33]) were enrolled, 57% of whom had optic pathway or hypothalamic target lesions. At the time of submission, median duration of treatment was 18 courses (range 2–48) and 21 subjects remained on therapy. Best responses reported to date are 6/35 (17%) partial response, 22/35 (63%) SD and 7/35 (20%) progressive disease with a 2-year progression-free survival of 75.7 + 8.3%, which met the design parameters for success. The most common attributable toxicities were grade 1 diarrhea, elevated AST, hypoalbuminemia, elevated CPK, maculo-papular rash, fatigue, paronychia, ALT elevation, acneiform rash and grade 2 CPK elevation. Rare grade 3 toxicities included CPK elevation (3), lymphopenia (2), paronychia (2) and ALT elevation (2). There was only one grade 4 CPK elevation. Five patients (14%) required dose reductions due to toxicity. There does not appear to be a notable difference in toxicities observed during initial selumetinib therapy versus re-treatment. In pLGG that has recurred/progressed following treatment with selumetinib, re-treatment with selumetinib appears to be effective with 80% of patients again achieving response or prolonged stable disease. Long-term follow-up is ongoing.

Diffuse leptomeningeal glioneuronal tumor (DLGNT) is an extremely rare disease, newly recognized in the 2016 WHO classification of tumors of the CNS. Most DLGNTs are low-grade neuroepithelial tumors with variable elements of neuronal/neurocytic and glial differentiation, have diffuse leptomeningeal enhancement on MRI, and typically harbor KIAA1549-BRAF fusions. Other alterations, such as the BRAF V600E substitution, are less common. Here, we present three cases of DLGNT with different presentations and outcomes. The first patient is a 2yr-old male with KIAA1549-BRAF fusion, and was treated with Carbo/VCR chemotherapy after a biopsy, with resultant ongoing stable disease for 3.5 years. The second patient, an 8yr-old male had the BRAF V600E point mutation and was treated with conventional chemotherapy (VCR/carboplatin). On progression, he received the BRAF inhibitor vemurafenib, achieving a complete response which last 14 month. The third patient, a 27 month old male, harbored a KIAA1549-BRAF fusion and was treated at diagnosis with the MEK inhibitor trametinib. The tumor has been radiographically stable in the context of clinical improvement for 21 months since the treatment initiation, ongoing 24 month. In summary, we present further evidence of MAPK pathway alterations in children with DLGNT. We describe a range of molecular presentations and clinical outcomes, including one patient treated with conventional chemotherapy with further stabilization of disease during 3.5 years and two patients who were successfully treated with targeted therapy.

BACKGROUND The use of BRAF inhibitors is widely accepted in adult oncology as treatment for BRAF mutated cancers. BRAF alterations are frequently found in both pediatric low grade and high-grade gliomas, which has opened a new door to targeted therapies for pediatric gliomas. Targeted therapy drugs are associated with predictable patterns of adverse events. However treating in children may potentiate unique challenges. We present our institutional experience of targeted therapy with a focus on adverse events. METHODS We conducted a retrospective chart review of patients treated with BRAF and/or MEK inhibitors between 2015–2019. RESULTS There are nine patients treated with either MEK inhibitor(n=) or the combination therapy(n=). The most common diagnosis was Pilocytic astrocytoma. Targeted therapy was chosen as salvage therapy in all patients. The most common side effect was a pruritic erythematous rash, observed in 8 out of 9 patients. Cardiac toxicity (Grade 2, n=1) and GI toxicity (Grade 3, n=1) were found in patients treated with MEK inhibitor. Both cases resulted in cessation of therapy or significant decreased dose respectively. While two patients died due to progression of disease and two other continued to progress, 5 patients have demonstrated stable disease while on therapy. CONCLUSIONS Our study revealed the incidence of severe adverse events in two patients with BRAF targeted therapy. Due to the potential life-long use of targeted therapy, it is important to follow guidelines of adverse event monitoring and to develop a prevention and management strategy for severe adverse events.

INTRODUCTION Low grade gliomas (LGG) are the most common pediatric brain tumors. Tumors not amenable to resection can recur or progress despite treatment with chemotherapy and/or radiation. Recent discovery of the activation of the mitogen-activated-protein-kinase (MAPK) pathway as the primary oncogenic driver for this group of tumors has led to a shift towards the use of BRAF and MEK inhibitors. METHODS Herein we performed a chart review of seven pediatric LGG treated with trametinib, a MEK inhibitor. While most were treated in the relapse setting, one patient was treated for de novo LGG as a result of experiencing multiple severe adverse effects to conventional agents. RESULTS Median age was 14 years old (range: 5 to 17 years). Six of seven patients had tissue for molecular characterization. The 2 patients with Neurofibromatosis Type 1 (NF-1) carried no other molecular aberrations. Two had the BRAF V600e mutation (1 had a concurrent PTPN11 mutation) and 2 were positive for the KIAA1549-BRAF fusion. Average duration on treatment was 8 months (range: 3 to 31 months). Disease control was achieved in 6 of 7 subjects, with one PR as best response. One patient with concurrent BRAF V600e and PTPN11 mutations progressed on trametinib and was switched to dual BRAF and MEK inhibitor therapy. Most common toxicities were acne (57.1%), oral mucositis (42.9%), skin rash, and paronychia (both 28.6%). Three patients required dose reduction and/or intermittent dose interruption. CONCLUSION Our data supports the use of trametinib for both upfront and relapsed/refractory pediatric LGG.

INTRODUCTION Recent discoveries have provided valuable insight into the genomic landscape of pediatric low grade gliomas (LGGs) at diagnosis, facilitating molecularly targeted treatment. However, little is known about their temporal and therapy-related genomic heterogeneity. An adequate understanding of the evolution of pediatric LGGs’ genomic profiles over time is critically important in guiding decisions about targeted therapeutics and diagnostic biopsy at recurrence. METHODS Fluorescence in situ hybridization, mutation-specific immunohistochemistry, and exome analyses were performed on paired tumor samples from primary diagnostic and subsequent surgeries. RESULTS 101 tumor samples from 48 patients (43 with 2 specimens, 5 with 3 specimens) from 3 institutions underwent testing. BRAF fusion and BRAFV600E status were conserved in 100% and 97% of paired specimens, respectively. No loss or gain of IDH1 mutations or FGFR1, NTRK2, MYB, or MYBL1 rearrangements were detected over time. Histologic diagnosis remained the same in all tumors, with no acquired H3K27M mutations or malignant transformation. CDKN2A deletions were acquired in 7 patients (including 3 who received chemotherapy [2 with temozolomide] and 1 who received radiation), and were associated with a trend toward shorter time to progression (median: 5.5 vs. 13.0 months [p=0.08]). CONCLUSIONS Most targetable genetic alterations in pediatric LGGs, including BRAF alterations, are conserved at recurrence and following chemotherapy or radiation. However, CDKN2A deletion acquisition was demonstrated and may define a higher risk group. Given potential for targeted therapies for tumors acquiring CDKN2A deletions, performing a biopsy at recurrence may be indicated in certain patients, especially those with rapid progression.

BACKGROUND Pilomyxoid astrocytoma (PMA) is a glial tumor that occurs predominantly in the hypothalamic-chiasmatic region and rarely in spinal cord. It has similar features as pilocytic astrocytomas, with some distinct histological characteristics and worse prognosis. The 2007 WHO recognized PMA as a Grade II glioma due to its aggressive behavior and dissemination tendency, but according to 2016 version grading of the pilomyxoid variant is under research. Here we report a case with a rare location, aggressive behavior and rapid progression. CASE PRESENTATION: A 7-year-old boy presented with headache, nausea, vomiting. Imaging revealed an intramedullary tumor extending from C2 to C6 with hydrocephalus. A ventriculo-peritoneal shunt and complete surgical resection were performed with significant improvement in the patient’s condition. Histopathological findings were consistent with pilomyxoid variant of pilocytic astrocytoma, with negative BRAF V600E and MGMT. Three months later, the follow-up imaging revealed disease recurrence with leptomeningeal metastases, for which the patient received standard-dose craniospinal irradiation 35.2 Gy with boosts to tumor bed and metastatic sites 49.6 Gy and 54 Gy respectively. 11 months later tumor progression was revealed with new metastatic lesions in the bones. Patient received 6 cycles of chemotherapy with TMZ and Avastin, but continued to suffer disease progression on therapy and he succumbed to his disease at 24 months from diagnosis. CONCLUSION Given the rarity of documented patients with spinal pilomyxoid astrocytoma with rapid progression, as well as the lack of certain WHO classification and treatment guidelines, this case report might be useful for development of more efficient treatment strategies.

BACKGROUND The MAPK/ERK pathway is involved in cell growth and proliferation, and mutations in the BRAF paralog of this pathway have made it an oncogene of interest in pediatric cancer. Previous studies have identified that BRAF mutations as well as BRAF-KIAA1549 fusions are common in intracranial low-grade gliomas (LGGs). Fewer studies have tested for the presence of these genetic aberrations in spinal LGGs. The aim of this study was to better understand the prevalence of BRAF and other genetic aberrations in spinal LGG. METHODS We analyzed 46 spinal LGGs from children age 1–25 years from two institutions, Children’s Hospital Colorado (CHCO) and The Hospital for Sick Children (Sick Kids) for the presence of BRAF fusions or mutations. Data was correlated with clinical information. A 67 gene panel additionally screened for other possible genetic abnormalities of interest in the patient cohort from CHCO. In the Sick Kids cohort, BRAFV600E was tested for by ddPCR and IHC while BRAF fusions where detected by FISH, RT-PCR or Nanostring platform. RESULTS Of the 31 patient samples who underwent fusion analysis, 13 (42%) harbored the BRAF-KIAA1549 fusion. Overall survival (OS) for patients confirmed positive for BRAF-KIAA1549 was 100% compared to 76% for fusion negative patients. Other mutations of interest were also identified in this patient cohort including BRAFV600E, STK11, PTPN11, H3F3A, APC, TP53, PIK3CA (polymorphism), FGFR1, and CDKN2A deletion. CONCLUSION BRAF-KIAA1549 was seen in higher frequency than BRAFV600E or other genetic aberrations in pediatric spinal LGGs and trends towards longer OS although not statistically significant.

BACKGROUND Pediatric low-grade gliomas (LGG) not amenable to resection, while often indolent, represent a significant source of cancer-related morbidity and an unmet therapeutic need. Standardly, these patients are treated with sequential lines of chemotherapy, while delaying as long as possible radiation. Magnetic resonance-guided laser interstitial therapy (LITT) is a minimally invasive procedure that utilizes real-time MR thermography to ablate brain lesions. METHODS A 15-year-old girl was diagnosed with a suprasellar, hypothalamic LGG, BRAF V600E mutation positive. The tumor was unresectable, and due to progressive vision loss and headaches, the patient underwent treatment. Despite sequential trials of thioguanine/procarbazine/lomustine/vincristine, carboplatin/vincristine, dabrafenib, and combination dabrafenib/trametinib, the patient continued to experience debilitating headaches, malnutrition, school absenteeism, and overall poor quality-of-life. Using real-time, sequential MRI-thermometry and the Neuroblate cooled directional laser catheter, the bulk of the enhancing tumor was heated to a killing temperature. RESULTS At 1-year post LITT, the patient’s symptoms were dramatically improved, including greatly improved headaches, malnutrition, school absenteeism, and overall quality of life. LITT was generally well tolerated, though the patient had slight progressive left homonymous hemianopia, thought secondary to LITT impact on the optic tracts. The tumor progressively shrank over the year post-LITT to a peak of 42% volume reduction. CONCLUSION We report a case of a pediatric patient with an unresectable low grade glioma who underwent LITT with excellent clinical and radiographic effects. LITT should be considered for children with unresectable and morbid LGGs that fail to respond to more conventional therapies.

Current consensus for the treatment of optico-hypothalamic astrocytoma (OHA) is a chemotherapy-first policy, limiting the role of surgery for histopathological diagnosis and partial decompression. However, a subgroup of OHA patients show resistance to chemotherapy and have a worse prognosis. In this study, we retrospectively analyzed our clinical experiences of the treatment of patients with OHA in two university hospitals. We have extracted and analyzed the medical charts of 15 pediatric OHA patients treated in two university hospitals since 1990. NF-1-associated OHA patients were excluded. Patient ages ranged from 10 months to 21 years (median 7 years). Out of 15 cases, 12 patients had a tumor larger than 3 cm and classified as Dodge 3. The final histopathological diagnosis was pilocytic astrocytoma in 13 cases. Three patients with tumors classified as Dodge 1 or 2 show good prognosis only by biopsy or partial resection. However, regarding Dodge 3 tumor, patient prognosis is worse regardless of chemotherapy and radiotherapy. After the initial surgery, chemotherapy was administered in 11 cases and radiotherapy in 5 cases. Multiple surgeries are needed for tumor control in 7 patients. Four patients died of tumor progression or treatment-associated complications. When the initial tumor is large enough to cause neurological deterioration, a chemotherapeutic tumor suppressive effect might be limited in a subset of large OHA cases. Therefore, it is important to consider the proper timing of safe surgical decompression in the early phase when a large tumor does not respond to chemotherapy.

BACKGROUND Pediatric low-grade gliomas (PLGG) are the most frequent brain tumors in children. It is now known that the majority of PLGG have activation of the MAPK/ERK pathway. We hypothesize that we will observe responses in recurrent/refractory PLGG treated with trametinib. METHODS This is a multicenter phase II including three progressing/refractory PLGG groups: NF1 patients, KIAA1549-BRAF fusion patients and patients with other activation of the MAPK/ERK pathway (excluding V600E). Patients will receive daily oral trametinib for a total of 18 cycles of 28 days. A total of 104 patients will be enrolled in seven Canadian centers. Secondary objectives include the assessment of progression-free survival, tolerability of trametinib, serum levels of trametinib and evaluation of quality of life during treatment. RESULTS As of January 7 2020, 28 patients have been enrolled (NF1: 6 patients, KIAA1549-BRAF fusion: 17, other: 5 including 3 patients FGFR1 alteration). Median age is 8.5 years (range 2.5–25.4 years). Median follow-up is currently 4.6 months (range 0.16–14.7 months). Twenty patients are currently evaluable. Best response includes: 1 complete response (5%), 3 partial response (15%), 4 minor response (20%), 8 stable disease (40%), 4 progressive disease (20%). 8 patients (28,5%) discontinued treatment: 4 for progressive disease, 3 adverse event (alanine aminotransferase increase), 1 withdrew. CONCLUSION Trametinib is potential effective targeted therapy for patients with recurrent/refractory PLGG. Overall treatment is well tolerated. This ongoing trial will continue to gather data on response rate, duration of response and safety of trametinib for PLGG.

Molecularly targeted therapy with MEK inhibitors is increasingly being incorporated into the treatment of pediatric low-grade gliomas (LGGs). Trametinib is an orally available MEK1/2 inhibitor that has demonstrated tumor control in LGGs with BRAF alterations. Safe expansion of MEK inhibitor therapy within the pediatric patient population demands adequate understanding of and surveillance for potential MEK-inhibitor specific toxicities, especially among young children. Hyponatremia has been reported in adult patients receiving BRAF/MEK inhibitor combination treatment as well as in two pediatric patients with known diabetes insipidus treated with trametinib monotherapy. To our knowledge, single-agent trametinib has not previously been reported to be associated with hyponatremia in children in the absence of an underlying endocrinopathy. We present a case of hyponatremia associated with trametinib use in an infant with progressive LGG without known endocrine dysfunction, which recurred after significant dose reduction. Therapy with an alternative MEK1/2 inhibitor, binimetinib, provided excellent tumor response without hyponatremia. Hyponatremia is a rare but serious side effect of trametinib, even without underlying pituitary dysfunction. Infants and patients lacking the ability to quickly regulate fluid intake in response to osmolality changes are at particular risk of suffering severe consequences from hyponatremia and should be monitored closely with initiation of trametinib. Switching to a different drug within the same class may offer an alternative to significant dose reduction or discontinuation due to this toxicity.

Chemotherapy after biopsy or partial resection of the tumor is widely accepted as first-line therapy for optic pathway pilocytic astrocytoma. However, there is no standard of care for recurred tumors. We investigated our cases which showed recurrence after initial therapy. Retrospective analysis of four recurrent optic pathway pilocytic astrocytoma cases was performed. All patients underwent partial resection or biopsy of the tumor, and all received carboplatin and etoposide- based chemotherapy as initial treatment. Mean age at first therapy was 2.3 years old, and mean time from initial therapy to recurrence of the tumor was 5.6 years. Two patients were totally blind at the time of recurrence, and other two had partial visual field losses. One patient underwent total resection of the tumor, and other three patients underwent partial resection followed by chemotherapy. Visual function in patients with visual acuity did not deteriorate after removal of the recurrent tumor. There was no recurrence of the tumor who underwent total resection. All of the three patients who had partial resection followed by chemotherapy recurred. Mean time from first recurrence to second recurrence was 1.8 years. After second recurrence, all patients underwent radiation therapy. One patient died due to malignant transformation of the tumor. For recurrent optic pathway pilocytic astrocytoma, prognosis may be better if total resection of the tumor without deteriorating the vision is possible.

Pediatric low-grade gliomas (pLGG) account for one third of all central nervous system (CNS) tumors. MRI is the preferred imaging modality for diagnosis and response evaluation. This study aims to evaluate if radiographic characteristics of pLGG at diagnosis are prognostic. Medical records of 700 pLGG patients were reviewed who were seen between 1998- 2019 at our institution. Summary statistics were provided to describe patient demographic and clinical characteristics. 603 patients were not eligible because incomplete records, 97 patients were identified and eligible for the review. There were 45 females and 52 males with the mean age of 6.5 years at diagnosis. Patients were categorized based on contrast enhancement to 2 groups; none/mild versus moderate/high with 65 and 32 patients respectively. 31 patients had infiltrative glioma (32.3%) with more than one lobe involved at diagnosis. Fifteen patients (15.46%) had hydrocephalous at initial diagnosis. 32 patients (32.9%) did not have any treatment and remained stable while 65(67.0%) had either surgery, chemotherapy or radiation or combination. 21 patients had neurofibromatosis type-1(NF-1) with better outcome comparing to non-NF1 as previously reported. No statistically significant difference in outcome was found based on the imaging characteristics at diagnosis including contrast enhancement, hydrocephalus, tumor size, presence of cyst or infiltrative tumors. The 5 years PFS rate for the entire cohort was 47%. Our study results are limited by low patient number, hence collaborative multi-institutional studies are warranted to delineate consensus and investigate prognostic factors to improve the outcome of pLGG.

Epilepsy is a common diagnosis among pediatric patients with supratentorial tumors, particularly infiltrating gliomas. The ketogenic diet can be a successful antiepileptic therapy for patients with medically intractable epilepsy. Acetoacetate, a main ketone released during ketosis, has been shown to increase BRAFV600E binding to MEK1 and MEK1 phosphorylation in BRAFV600E mutant melanoma cells, thereby promoting proliferation and tumor growth (Kang et al, 2015, Xia et al, 2017). BRAFV600E mutation is common in pediatric low-grade gliomas. Therefore, use of a ketogenic diet to manage coincident epilepsy could, in theory, promote tumor growth. However, this has not been previously reported in a human patient. We present a 3 year-old male with a non-NF1 optic pathway BRAFV600E mutant pilocytic astrocytoma and medically intractable epilepsy. He was treated with carboplatin and bevacizumab for 1 year, with good tumor response and vision recovery. He showed stable, non-progressive disease for several months. He was placed on a ketogenic diet 9 months into treatment and became seizure free. Tumor recurrence occurred at 8 months off therapy, at which time a biopsy demonstrated BRAFV600E mutation. The tumor progressed rapidly despite treatment with Trametinib and Dabrafenib, leading to salvage therapy with carboplatin, vinblastine, bevacizumab, and XRT, without tumor control. We discuss the potential effect of the ketogenic diet on this patient’s outcome.

BACKGROUND Targeted therapy aimed at modulating the RAS/RAF/MEK/ERK pathway is of increasing interest for patients with plexiform neurofibromas and low-grade gliomas. Trametinib is an FDA-approved MEK inhibitor that has little published pediatric experience to date. METHODS A retrospective chart review of patients treated with trametinib for low-grade gliomas (LGG) and/or plexiform neurofibromas (PN) between 2015–2018 was conducted at Children’s Hospital Colorado. Data collected included patient demographics, lesion location, Neurofibromatosis type 1 (NF1) status, best response of PN/LGG to trametinib, duration of trametinib therapy, and reported toxicities at least possibly attributed to trametinib. RESULTS Thirty (57% male; 73% NF1) patients were identified. Sixteen (53%) patients had PN only, 12 (40%) had LGG only, and two (7%) patients had both PN and LGG. The most common LGG location was the optic pathway/hypothalamus (72%). The most common location of PN was the face (63%). Two-thirds (8/12) of patients with LGG had a BRAF alteration or NF1 mutation. The median age at start of trametinib therapy was 9.9 years (range, 2.0 – 18.8 years). The median duration of trametinib therapy was 0.8 years (range 0.1 – 2.9 years). The most commonly reported adverse event was rash. No patients developed retinal toxicity or cardiotoxicity. Only two (7%) patients discontinued for toxicity and one (3%) for progressive disease. CONCLUSIONS Trametinib can be administered without significant toxicity to children with PN or LGG. Clinical benefit is noted in this cohort; however, prospective clinical trials are necessary to characterize efficacy formally.

Compelling body of evidence exists to use bevacizumab, a humanized monoclonal anti-VEGF antibody, in selected paediatric patients with low-grade CNS tumours. Common toxicities of bevacizumab, hypertension, proteinuria, epistaxis, mucosal perforation, decreased wound healing are well reported. However, the effect of bevacizumab on female ovarian function and long-term fertility is still being documented. Current evidence for bevacizumab-associated decline in ovarian function is largely from breast and colon cancer cohorts where exposure to multimodal chemotherapy confounds causative relationships. Fertility counseling and oocyte cryopreservation is currently offered as standard of care to post-pubertal females at high risk of infertility due to high-dose radiation and chemotherapy. Adolescent females with low-grade CNS tumours on bevacizumab represent a unique population which could potentially be at high risk for infertility. We report 2 cases of adolescent girls treated with bevacizumab as a single agent and in combination with vinblastine for NF2-associated vestibular schwannomas and brainstem glioma respectively. Both patients were post-pubertal with established menstrual cycles and normal baseline FSH/LH/oestradiol/AMH values prior to commencement of therapy. They became amenorrhoeic shortly after starting of therapy with levels of FSH/LH/oestradiol suggestive of premature ovarian failure. One patient has remained asymptomatic, whereas the other has developed profound post-menopausal symptoms interfering with quality of life which necessitated commencement of hormone-replacement therapy. Appropriate pretreatment fertility investigation and consultation should be offered to all post-pubertal females starting on bevacizumab. Further research into the long-term effects of gonadal toxicity in both females and males with drugs inhibiting angiogenesis is needed.

BACKGROUND Children with BRAF V600-mutant LGG have suboptimal response to standard chemotherapy. Previously, D (BRAF V600 inhibitor) monotherapy has demonstrated clinical benefit in this population. We report interim analysis results of pediatric patients with recurrent/refractory BRAF V600-mutant LGG treated with either T (MEK1/2 inhibitor) monotherapy or D+T combination therapy. METHODS This is a 4-part, open-label, multicenter, phase I/II study (NCT02124772) in pediatric patients ( RESULTS Of 49 pediatric patients with BRAF V600-mutant LGG (T, n=13; D+T, n=36) enrolled, pooled efficacy data was available for both treatments while safety data was available for 30 patients (T, n=10; D+T, n=20). Most patients (n=8/10) receiving T monotherapy withdrew/discontinued the treatment in contrast to 3/20 in the D+T group. Pyrexia occurred in 50% of patients (n=5/10) in the monotherapy group and was a frequent AE in the combination group (75%; n=15/20). Objective response rate per independent review was 15% (95% CI, 2%–45%) with T monotherapy and 25% (95% CI, 12%–42%) with D+T combination therapy. Seven patients (54%) on monotherapy and 33 patients (92%) on combination therapy had stable disease or better. CONCLUSION In pediatric patients with previously treated BRAF V600-mutant LGG, T monotherapy and D+T combination therapy demonstrated clinical activity, with pyrexia being a common AE.

Children with pediatric gliomas harboring BRAF V600E mutation have a poor outcome with current chemoradiation strategies. Our aim was to study the role of targeted BRAF inhibition in these tumors. We collected clinical, imaging, molecular and outcome information from BRAF V600E glioma patients treated with BRAFi across 29 centers from multiple countries. Sixty-seven patients were treated with BRAFi (56 pediatric low grade gliomas, PLGG and 11 pediatric high grade gliomas, PHGG) for up to 5.6 years. Objective responses were observed in 80% of PLGGs compared to 28% with conventional chemotherapy (p

Pediatric optic nerve glioma (ONG) is a rare, sight-threatening tumor. We previously reported clinical, radiologic, histopathologic, and molecular characteristics of pediatric ONG patients treated at Columbia University Medical Center between 2000–2017. Here we evaluate this cohort and one additional patient using quantitative multiple immunofluorescence (qmIF) and next generation sequencing (NGS) using the Columbia Combined Cancer Panel (CCCP). For qmIF, 4 micron immuno-blank slides were stained for CD3, CD8, CD68, CD163, HLA-DR, and Olig2. QmIF images were analyzed and data were processed in R studio and compared based on tumor mutation and treatment history. QmIF failed in 1 case and CCCP failed in 2 cases. CCCP confirmed KIAA1549:BRAF fusions in 2 patients, identified NF1 in 2 patients, and demonstrated both a KIAA1549:BRAF fusion and SETD2 mutation in the added case. Qualitative analysis showed immune infiltrate across cases included macrophages (CD68+, 1.6–6.5% of all cells) and T cells (CD3+, 0.4% to 1.5%). Non-cytotoxic T cells (CD3+CD8-) comprised 60.7–100% of the T cell compartment. There was no difference when comparing mutation groups. However, patients who previously received radiation had increased CD3+, specifically CD3+CD8- cells compared to non-irradiated patients (p=0.01 and p

An 11 y.o. female presented to a GI specialist with complaints of morning vomiting and periumbilical abdominal pain for several months. Had progressing symptoms with GI work-up for ~1 year. She developed diplopia and worsening headaches. Imaging revealed a T2/FLAIR hyperintense mass in the 4th ventricle with heterogeneous enhancement and obstructive hydrocephalus. Three T2 bright, non-enhancing, subcentimeter masses identified in the right cerebellum. Due to poor differentiation between tumor and normal tissue at brainstem, only partial resection (PR) was feasible. Pathology initially called pilocytic astrocytoma (PA). All symptoms resolved after PR. Slow progression in the tumor and “satellite” lesions noted over two years. Second opinion and molecular typing reclassified the tumor as rosette-forming glioneuronal tumor (RFGNT) with a mutation in PIK3CA. Therapy started with vinblastine and carboplatin with stable disease x 7 months, discontinued due to allergic reaction to carboplatin. Initiated therapy with everolimus, an mTOR inhibitor. The tumor’s characteristics on imaging changed with initial growth and increase in peripheral enhancement in one satellite and the primary tumor. Nevertheless, we persevered. When comparing pre-treatment MRI to most recent 7 months later, there has been an overall decrease in volume of expansile heterogenous tumor along the margins of the fourth ventricle. The degree of peripheral enhancement associated with the mass has increased. RFGNT is a rare tumor included in WHO classification since 2007. Ellezam et al identified recurrent PIK3CA mutations. To our knowledge, this is the only report of treatment targeting the mutation. We report a radiographic response despite initial growth.

OBJECTIVE To estimate the 6-month Progression Free Survival (PFS6) associated with everolimus for progressive/recurrent pLGGs and to determine if activated PI3K/Akt/mTOR pathway as measured by positive phosphorylated-ribosomal protein S6 (p-RPS6) status was associated with response. METHOD: Patients 3–21 years of age with recurrent or progressive pLGG were enrolled. Everolimus was administered orally at 5 mg/m2 daily. Tissue availability for molecular analysis was mandatory. Immunohistochemistry (IHC) for p-RPS6 was performed centrally. An adaptive Simon two-stage design was employed based on p-RPS6 status. Based on results of the first stage, enrollment in the second stage was either limited to pathway activated patients or open to all subjects. RESULTS From December 2012 to July 2019 a total of 65 subjects enrolled [median age 9 years (range 3–19); 43% female]. As of December 15, 2019 median number of treatment cycle is 8 (range 1–24); 7 patients remain on treatment. Toxicity profile is similar to published reports with rash and elevated lipid profiles as most common adverse events. PFS6 for the entire cohort is 63%; PFS6 is 64% for the activated and 61% for the non-activated patients. Central imaging review (n=52) revealed 1 partial response, 1 complete response, 33 stable disease, and 17 progressive disease at the end of study treatment. Initial molecular analysis identified BRAF alterations in 35/65 patients. CONCLUSION Everolimus is well tolerated and active in a subset of pLGGs. Ongoing analyses will assess predictive biomarkers of response and will be reported at the meeting.

Pediatric Low Grade Gliomas (PLGGs) display heterogeneity regarding morphology, genomic drivers and clinical outcomes. The treatment modality dictates the outcome and optimizing patient management can be challenging. In this study, we profiled a targeted panel of cancer-related genes in 37 Saudi Arabian patients with pLGGs to identify genetic abnormalities that can inform prognostic and therapeutic decision-making. We detected genetic alterations (GAs) in 97% (36/37) of cases, averaging 2.51 single nucleotide variations (SNVs) and 0.91 gene fusions per patient. The KIAA1549-BRAF fusion was the most common alteration (21/37 patients) followed by AFAP1-NTRK2 (2/37) and TBLXR-PI3KCA (2/37) fusions that were observed at much lower frequencies. The most frequently mutated) genes were NOTCH1 3 (7/37), ATM (4/37), RAD51C (3/37), RNF43 (3/37), SLX4 (3/37) and NF1 (3/37). BRAF V600E mutations were observed in only 2/37 patients, while H3F3A (K27M) histone mutations were not detected. Interestingly, we identified a GOPC-ROS1 fusion in an 8-year-old patient whose tumor lacked BRAF alterations and histologically classified as low grade glioma. The patient underwent gross total resection (GTR) currently he is disease free. To our knowledge this is the first report of GOPC-ROS1 fusion in PLGG which may represent a genomically-distinct subgroup of pLGGs that could be targeted with oral target therapy crizotinib. Taken together, we reveal the genetic characteristics of pLGG Saudi patients can enhance diagnostics and therapeutic decisions. In addition, we identified a GOPC-ROS1 fusion that may be a biomarker for pLGG. Our study proves the possibility of using genetic profiling to guide optimal treatment strategies for pLGG in Saudi population

INTRODUCTION Low grade glioma (LGG) is the most common central nervous system (CNS) tumor in children accounted for 30–50%. Regarding benign characteristic of disease, surgical management remains the mainstay of treatment. However, surgical approach is limited in some conditions such as location at brainstem or infiltrative tumor. Chemotherapy and radiation treatments have been included in order to control tumor progression. The 5-years survival rate is approach 90% especially in patients who receive complete resection. However, the outcome of children with LGG in low to middle income is limited. Therefore, the aim of the study was to determine long-term outcome of children with newly diagnosed LGG. METHODS A retrospective study enrolled children aged RESULTS A total of 40 patients, female to male ratio was 1:1.35 and mean (SD) for age was 6.7 (4.0) years. The most common location was optic chiasmatic pathway (42.5%), followed by suprasellar region (25.0%). Sixty percent of patients received at least partial tumor removal. Chemotherapy and radiation had been used in 70% and 10.0% respectively. The 10-year progression free survival was 74.1±11.4% and overall survival was 96.2±3.8%. SUMMARY: Treatment of Pediatric LGG mainly required surgical management, however, chemotherapy and radiation had been used in progressive disease. The outcome was excellent.

Low grade gliomas are the most common type of central nervous system tumors among children. Despite the fact that they are not typically life threatening, low grade gliomas remain a significant clinical challenge. Case Study: Patient is a 4-year-old male who presented at 20 months of age with several weeks of ataxia, emesis, and head tilt. Imaging revealed a right temporal lobe lesion; he was subsequently taken to surgery, where a gross total resection was achieved. Imaging 9 months post resection revealed recurrent disease within the right temporal region with leptomeningeal involvement. Four months later imaging revealed progression of multifocal disease and new growth within the sella. At this time the patient started standard treatment, Carboplatin and Vincristine, per CCG 9952A. Persistent slow progression was observed despite receiving standard therapy. The patient developed a grade 3 reaction to carboplatin, worsening with each subsequent dose. At this time, he was referred to our Precision Genomics Neuro Oncology program for tumor molecular characterization. Somatic tumor testing revealed an ETV6-NTRK3 fusion, at which time standard treatment was stopped, and patient began targeted therapy, Larotrectinib. Imaging was preformed 2 months post start of targeted therapy and revealed interval decrease in size of previously enhancing nodular lesions; findings consistent with treatment response. Disease burden continues to decrease with therapy. This case illustrates a clear benefit of using molecular guided therapy in low grade gliomas.

Pilocytic astrocytomas (PAs) and other pediatric low-grade gliomas (pLGGs) exhibit aberrant activation of the MAPK signaling pathway caused by genetic alterations, most commonly KIAA1549:BRAF fusions, BRAF V600E and NF1 mutations. In such a single-pathway disease, novel drugs targeting the MAPK pathway (MAPKi) are prime candidates for treatment. We developed an assay suitable for pre-clinical testing of MAPKi in pLGGs, aiming at the identification of novel MAPK pathway suppressing synergistic drug combinations. We generated a reporter plasmid (pDIPZ) expressing destabilized firefly luciferase driven by a MAPK-responsive ELK-1-binding element, packaged in a lentiviral vector system. We stably transfected pediatric glioma cell lines with a BRAF fusion (DKFZ-BT66) and a BRAFV600E mutation (BT-40) background, respectively. Measurement of MAPK pathway activity was performed using the luciferase reporter. pERK protein levels were detected for validation. We performed a screen of a MAPKi library and calculated Combination Indices of selected combinations. The MAPKi library screen revealed MEK inhibitors as the class inhibiting the pathway with the lowest IC50s, followed by ERK and second generation RAF inhibitors. Synergistic effects in both BRAF-fusion and BRAFV600E mutation backgrounds were observed following combination treatments with different MAPKi classes (RAFi/MEKi, > RAFi/ERKi > MEKi/ERKi). We have generated a novel reporter assay for medium- to high-throughput pre-clinical drug testing of MAPKi in pLGG cell lines. MEK, ERK and next-generation RAF inhibitors were confirmed as potential treatment approaches for KIAA1549:BRAF and BRAFV600E mutated pLGGs. Synergistic suppression of MAPK pathway activity upon combination treatments was revealed using our assay in addition.

Paediatric low-grade gliomas (pLGGs) constitute the largest group of childhood CNS tumours. They often cause significant disability and morbidity, despite their indolent growth and the good survival rate of patients. The most common genetic alterations in these tumours, KIAA1549:BRAF fusion and BRAFV600E mutation, lead to abnormal activation of MAPK signalling. The central role of this pathway in pLGG development is emphasized by the occasional presence of other MAPK-activating alterations such as RTK mutations. It is not known how these different aberrations can induce the variety of clinical phenotypes seen in pLGG. Here, we compared pilocytic astrocytomas (PAs) containing the KIAA1549:BRAF fusion with glioneuronal tumours (GNTs) containing the BRAFV600E mutation, to identify differentially activated downstream targets of the MAPK pathway. Liquid chromatography tandem mass spectrometry (LC-MS/MS) was used as a multi-proteomic approach. Kinase Set Enrichment Analysis (KSEA) using PhosphositePlus and NetworkIN was used to determine relative enrichment of kinase activity in the tumours compared to healthy control brain tissue. Significant similarities and differences were found in the two tumour types. For example, more robust MAPK activation was found in the GNTs than in PAs. However, while PI3K/AKT1/mTOR signalling was active in both PAs and GNTs, there was statistically higher activation in the PAs. In both tumour types, there was significant reduction in casein kinase 2 activity, which likely affects nuclear translocation of ERK and, in turn, alters the range of its phosphorylated substrates. We will present these data together with transcriptomics to further characterise the downstream targets of these genetic alterations.

Pleomorphic xantoastrocytoma (PXA) is a typically well circumscribed astrocytic neoplasm that can progress to anaplastic PXA with an aggressive biologic behavior and worse prognosis. Histological features of anaplastic progression include increased proliferation, necrosis, microvascular proliferation, loss of pericellular reticulin, and increased infiltrative growth. Genetically anaplastic PXA is characterized by the combination of CDKN2A biallelic inactivation and oncogenic RAF kinase signaling, as observed in PXA, as well as a relatively small number of additional genetic alterations, with the most common being TERT amplification or promoter mutation (Phillips et al 2018). Common to both PXA and anaplastic PXA is the perivascular accumulation of lymphocytes. Given the potential importance of the immune response in brain tumors we asked whether the immune response in anaplastic PXA was different than that in PXA and in IDH-mutant diffuse glioma. To do this we used quantitative multiplex immunofluorescence of scanned slides and quantified the populations and phenotypes of T cells and microglia/macrophages in tumors identified from the UCSF Brain Tumor Center Biorepository and from the archives of the UCSF Neuropathology Division. All tumors were molecularly characterized by immunostaining and/or comprehensive genomic profiling. A total of 30 PXA, including 6 paired tumors before and after tumor progression, and 30 diffuse glioma were examined. Immunostaining for T cell subsets included CD3, CD8, and FOXP3 and for microglial/macrophages included Iba1, CD204, and CD163. Using quantitative multiplex immunostaining we assess immune cell subsets and their localization within the tissue highlighting the perivascular CD3+ lymphocytes. Our data suggest differences in the quantity and quality of immune cells in anaplastic PXA.

BACKGROUND: Central nervous system (CNS) tumor is the most common solid neoplasm in children. Here we report clinical features of children with CNS tumor treated in our institute during recent 11 years. METHODS: Retrospective study was conducted in children with CNS tumor treated in Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, during 2006 to 2017. Clinical data were collected. Statistical calculation was conduct for characteristic analyses. RESULTS: 1136 cases of CNS tumor in children were collected, with 712 males and 424 females. Age ranges were 9.33% in infants (< 1 y/o), 26.32% in toddler (1 - 3 y/o), 35.30% in preschool children (3 - 7 y/o), 27.11% in school-age children (7 - 15 y/o) and 1.94% in adolescence (> 15 y/o). 437 cases were diagnosed with WHO I-II grades and 392 cases were with WHO III-IV grades. There were 548 supratentorial tumors and 441 subtentorial tumors. The most common tumor type was medulloblastoma (n=168, 14.79%), followed by pilocytic astrocytoma (n=166, 14.61%). CONCLUSION: The gender ratios in different age ranges were stable, with high incidence in male than in female. In total, low grade tumors were more common than high grade tumors. Compare to our previous report, pilocytic astrocytoma was second most common tumor, following medulloblastoma.