scholarly journals LGG-12. TRAMETINIB FOR PEDIATRIC LOW GRADE GLIOMAS: A SINGLE INSTITUTION EXPERIENCE

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii368-iii368
Author(s):  
Mustafa Barbour ◽  
Michael Angelo Huang
Keyword(s):  
De Novo ◽  
Mapk Pathway ◽  
Neurofibromatosis Type ◽  
Mek Inhibitor ◽  
Pediatric Brain Tumors ◽  
Mitogen Activated Protein Kinase ◽  
Braf V600e ◽  
Low Grade ◽  
Low Grade Gliomas ◽  
Best Response

Abstract 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.

scholarly journals LGG-27. TARGETED THERAPY FOR PEDIATRIC LOW-GRADE GLIOMAS AND PLEXIFORM NEUROFIBROMAS WITH TRAMETINIB

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii371-iii371
Author(s):  
Tiffany Nguyen ◽  
Kathleen McMahon ◽  
Molly Hemenway ◽  
Jean Mulcahy Levy ◽  
Nicholas Foreman ◽  
...  
Keyword(s):  
Targeted Therapy ◽  
Retrospective Chart Review ◽  
Neurofibromatosis Type ◽  
Mek Inhibitor ◽  
Low Grade ◽  
Plexiform Neurofibromas ◽  
Low Grade Gliomas ◽  
Common Location ◽  
Best Response ◽  
The Face

Abstract 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.

scholarly journals LGG-26. DIFFUSE LEPTOMENINGEAL GLIONEURONAL TUMOR (DLGNT) IN CHILDREN: DIFFERENT CLINICAL PRESENTATIONS AND OUTCOMES

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii371-iii371
Author(s):  
Andge Valiakhmetova ◽  
Ludmila Papusha ◽  
Ludmila Yasko ◽  
Alexander Druy ◽  
Alexander Karachunsky ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Braf Inhibitor ◽  
Complete Response ◽  
Mek Inhibitor ◽  
Braf V600e ◽  
Glioneuronal Tumor ◽  
Low Grade ◽  
Conventional Chemotherapy ◽  
Diffuse Leptomeningeal Glioneuronal Tumor ◽  
Braf Fusion

Abstract 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.

Polymorphous Low-Grade Neuroepithelial Tumor of the Young (PLNTY): Molecular Profiling Confirms Frequent MAPK Pathway Activation

2021 ◽  
Author(s):  
Cristiane M Ida ◽  
Derek R Johnson ◽  
Asha A Nair ◽  
Jaime Davila ◽  
Thomas M Kollmeyer ◽  
...  
Keyword(s):  
Copy Number ◽  
Mapk Pathway ◽  
Braf V600e Mutation ◽  
Mitogen Activated Protein Kinase ◽  
Braf V600e ◽  
Low Grade ◽  
Pathway Activation ◽  
Mitogen Activated Protein ◽  
Copy Number Changes ◽  
Cd34 Expression

Abstract Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a recently described epileptogenic tumor characterized by oligodendroglioma-like components, aberrant CD34 expression, and frequent mitogen-activated protein kinase (MAPK) pathway activation. We molecularly profiled 13 cases with diagnostic histopathological features of PLNTY (10 female; median age, 16 years; range, 5–52). Patients frequently presented with seizures (9 of 12 with available history) and temporal lobe tumors (9 of 13). MAPK pathway activating alterations were identified in all 13 cases. Fusions were present in the 7 youngest patients: FGFR2-CTNNA3 (n = 2), FGFR2-KIAA1598 (FGFR2-SHTN1) (n = 1), FGFR2-INA (n = 1), FGFR2-MPRIP (n = 1), QKI-NTRK2 (n = 1), and KIAA1549-BRAF (n = 1). BRAF V600E mutation was present in 6 patients (17 years or older). Two fusion-positive cases additionally harbored TP53/RB1 abnormalities suggesting biallelic inactivation. Copy number changes predominantly involving whole chromosomes were observed in all 10 evaluated cases, with losses of chromosome 10q occurring with FGFR2-KIAA1598 (SHTN1)/CTNNA3 fusions. The KIAA1549-BRAF and QKI-NTRK2 fusions were associated respectively with a 7q34 deletion and 9q21 duplication. This study shows that despite its name, PLNTY also occurs in older adults, who frequently show BRAF V600E mutation. It also expands the spectrum of the MAPK pathway activating alterations associated with PLNTY and demonstrates recurrent chromosomal copy number changes consistent with chromosomal instability.

Novel RAF Fusions in Pediatric Low-Grade Gliomas Demonstrate MAPK Pathway Activation

2021 ◽  
Author(s):  
Katherine T Lind ◽  
Hannah V Chatwin ◽  
John DeSisto ◽  
Philip Coleman ◽  
Bridget Sanford ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Enrichment Analysis ◽  
Mitogen Activated Protein Kinase ◽  
Immunofluorescent Staining ◽  
Low Grade ◽  
Normal Brain ◽  
Mapk Activation ◽  
Low Grade Gliomas ◽  
Pathway Activation ◽  
Mitogen Activated Protein

Abstract Brain tumors are the most common solid tumor in children, and low-grade gliomas (LGGs) are the most common childhood brain tumor. Here, we report on 3 patients with LGG harboring previously unreported or rarely reported RAF fusions: FYCO1-RAF1, CTTNBP2-BRAF, and SLC44A1-BRAF. We hypothesized that these tumors would show molecular similarity to the canonical KIAA1549-BRAF fusion that is the most widely seen alteration in pilocytic astrocytoma (PA), the most common pediatric LGG variant, and that this similarity would include mitogen-activated protein kinase (MAPK) pathway activation. To test our hypothesis, we utilized immunofluorescent imaging and RNA-sequencing in normal brain, KIAA1549-BRAF-harboring tumors, and our 3 tumors with novel fusions. We performed immunofluorescent staining of ERK and phosphorylated ERK (p-ERK), identifying increased p-ERK expression in KIAA1549-BRAF fused PA and the novel fusion samples, indicative of MAPK pathway activation. Geneset enrichment analysis further confirmed upregulated downstream MAPK activation. These results suggest that MAPK activation is the oncogenic mechanism in noncanonical RAF fusion-driven LGG. Similarity in the oncogenic mechanism suggests that LGGs with noncanonical RAF fusions are likely to respond to MEK inhibitors.

scholarly journals BRAF V600E mutation mediates FDG-methionine uptake mismatch in polymorphous low-grade neuroepithelial tumor of the young

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Kensuke Tateishi ◽  
Naoki Ikegaya ◽  
Naoko Udaka ◽  
Jo Sasame ◽  
Takahiro Hayashi ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Braf Inhibitor ◽  
Positron Emission Tomography Imaging ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Braf V600e ◽  
Low Grade ◽  
Protein Levels ◽  
Positron Emission ◽  
Methionine Uptake

Abstract We present a case of a 14-year old boy with tumor-associated refractory epilepsy. Positron emission tomography imaging demonstrated a region with heterogeneous high 11C-methionine uptake and a region with homogenous low 18F-fluorodeoxyglucose uptake within the tumor. Histopathological and genomic analyses confirmed the tumor as BRAF V600E-mutated polymorphous low-grade neuroepithelial tumor of the young (PLNTY). Within the high-methionine-uptake region, we observed increased protein levels of L-type amino acid transporter 1 (LAT1), a major transporter of methionine; c-Myc; and constituents of the mitogen-activated protein kinase (MAPK) pathway. We also found that LAT1 expression was linked to the BRAF V600E mutation and subsequent activation of MAPK signaling and c-Myc. Pharmacological and genetic inhibition of the MAPK pathway suppressed c-Myc and LAT1 expression in BRAF V600E-mutated PLNTY and glioblastoma cells. The BRAF inhibitor dabrafenib moderately suppressed cell viability in PLNTY. Collectively, our results indicate that BRAF V600E mutation-activated MAPK signaling and downstream c-Myc induces specific metabolic alterations in PLNTY, and may represent an attractive target in the treatment of the disease.

scholarly journals LGG-51. BRAF ALTERATIONS IN PEDIATRIC LOW-GRADE GLIOMAS: RESULTS FROM A BRAZILIAN COHORT

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii376-iii376
Author(s):  
Felipe Restine ◽  
Luis Henrique Sakamoto ◽  
Juliana Monte Real ◽  
Gregorio Pereira ◽  
Jennifer Marx Fernandes ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Braf V600e ◽  
Low Grade ◽  
Diffuse Astrocytoma ◽  
Central Nervous System Neoplasms ◽  
Low Grade Gliomas ◽  
Pilocytic Astrocytomas ◽  
First Results ◽  
Nervous System Neoplasms ◽  
Brazilian Cohort

Abstract BACKGROUND Pediatric low grade gliomas (PLGG) are the most common central nervous system neoplasms in children. These are driven almost exclusively by alterations in the RAS/MAPK pathway. Specifically, alterations in the BRAF gene have emerged as an important target for therapy. This study aimed to identify the frequency of BRAF alterations in a Brazilian cohort of PLGGs. RESULTS Forty-one patients diagnosed between 2001 and 2017 had enough FFPE tissue available for analysis. Real-time PCR test (n=35) was used to assess for BRAFV600E mutations, while BRAF fusions were detected by break-apart fluorescence in situ hybridization (n=30). The histologic distribution was as follows: 73% pilocytic astrocytoma, 12% ganglioglioma, 3% diffuse astrocytoma, 5% pleomorphic xanthoastrocytomas (PXA) and 7% NOS (n = 41). BRAF fusions were present in 21 patients (51%): 17 pilocytic astrocytomas, 2 xanthoastrocytoma, 1 pilomyxoid astrocytoma and 1 diffuse astrocytoma. BRAFV600E was detected in 4 cases (10%): 2 pilocytic astrocytomas, 1 ganglioglioma and 1 PXA. As expected, BRAF translocations were more frequent in pilocytic astrocytomas (p<0.001). From 22 patients treated in our institution, 59% were male with a mean age of 9.7 years, 50% occurred in the posterior fossa and 77% treated by surgery only. One patient relapsed and died from disease (BRAF V600E positive) (follow-up median=44.7 months). These are the first results using a CLIA method showing the frequency of BRAF abnormalities in a Brazilian population. Although preliminary, BRAF alterations are present in 61% of the cases emphasizing the importance of incorporating this analysis in the current work-up guidelines.

Molecular Alterations Of Low-Grade Gliomas In Young Patients: Strategies And Platforms For Routine Evaluation

2021 ◽  
Author(s):  
Iman Dandapath ◽  
Rituparna Chakraborty ◽  
Kavneet Kaur ◽  
Swati Mahajan ◽  
Jyotsna Singh ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Young Patients ◽  
Steering Committee ◽  
Mitogen Activated Protein Kinase ◽  
Low Grade ◽  
Low Grade Gliomas ◽  
Molecular Alterations ◽  
Integrated Diagnosis ◽  
Mitogen Activated Protein ◽  
Diffuse Gliomas

Abstract In recent years, it has been established that molecular biology of pediatric low-grade gliomas (PLGGs) is entirely distinct from adults. The majority of the circumscribed pediatric gliomas are driven by mitogen-activated protein kinase (MAPK) pathway, which has yielded important diagnostic, prognostic, and therapeutic biomarkers. Further, the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy (cIMPACT) Steering Committee in their fourth meeting, suggested including a panel of molecular markers for integrated diagnosis in "pediatric type" diffuse gliomas. However, a designated set of platforms for the evaluation of these alterations has yet not been mentioned for easier implementation in routine molecular diagnostics. Herein, we have reviewed the relevance of analyzing these markers and discussed the strategies and platforms best apposite for clinical laboratories.

scholarly journals CS-03 BRAF V600E mutation mediates FDG-methionine uptake mismatch in polymorphous low-grade neuroepithelial tumor of the young

2020 ◽  
Vol 2 (Supplement_3) ◽  
pp. ii20-ii20
Author(s):  
Takahiro Hayashi ◽  
Kensuke Tateishi ◽  
Naoki Ikegaya ◽  
Naoko Udaka ◽  
Jo Sasame ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Positron Emission Tomography Imaging ◽  
Mapk Signaling ◽  
Braf V600e Mutation ◽  
Mitogen Activated Protein Kinase ◽  
Braf V600e ◽  
Low Grade ◽  
Protein Levels ◽  
Positron Emission ◽  
Methionine Uptake

Abstract We present a case of a 14-year old boy with tumor-associated refractory epilepsy. Positron emission tomography imaging demonstrated a region with heterogeneous high 11 C-methionine uptake and a region with homogenous low 18 F- fluorodeoxyglucose uptake within the tumor. Histopathological and genomic analyses confirmed the tumor as BRAF V600E-mutated PLNTY (polymorphous low-grade neuroepithelial tumor of the young). Within the high-methionine-uptake region, we observed increased protein levels of L-type amino acid transporter 1 (LAT1) and constituents of the mitogen-activated protein kinase (MAPK) pathway. We also found that LAT1 expression was linked to BRAF V600E mutation and subsequent activation of MAPK signaling. Pharmacological inhibition of the MAPK pathway suppressed LAT1 expression and cell viability in PLNTY cells. Collectively, our results indicate that BRAF V600E mutation-activated MAPK signaling induces specific metabolic alterations in PLNTY, and may represent an attractive target in the treatment of the disease.

scholarly journals LGG-14. MULTI-OMIC ANALYSIS OF MAPK ACTIVATION IN PEDIATRIC PILOCYTIC ASTROCYTOMA

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii368-iii368
Author(s):  
Romain Sigaud ◽  
Florian Selt ◽  
Thomas Hielscher ◽  
Nina Overbeck ◽  
Diren Usta ◽  
...  
Keyword(s):  
Target Genes ◽  
Profile Analysis ◽  
Mapk Pathway ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Low Grade ◽  
Brafv600e Mutation ◽  
Braf Fusion ◽  
Mapk Inhibitors ◽  
Data Layers

Abstract 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.

scholarly journals TMOD-23. A NOVEL BRAF V600E LOW-GRADE GLIOMA MOUSE MODEL HIGHLIGHTS EXOMIC AND TUMOR IMMUNE ALTERATIONS AND DIFFERING THERAPEUTIC RESPONSES IN LOW- AND HIGH-GRADE GLIOMAS

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii232-ii233
Author(s):  
Anne Marie Barrette ◽  
Lasse Meyer ◽  
Yoko Hirata ◽  
Stefan Grossauer ◽  
Edbert Lu ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Low Grade Glioma ◽  
Braf V600e ◽  
Common Mutation ◽  
Low Grade ◽  
High Grade ◽  
Checkpoint Inhibition ◽  
Immune Infiltrate ◽  
Low Grade Gliomas

Abstract Pediatric low-grade glioma (pLGG), the most common brain cancer in children, is difficult to treat especially at recurrence. The BRAF V600E mutation is the second most common mutation in pLGG, and in a high-risk group for progression is associated with deletion of the tumor suppressor CDKN2A. A better understanding of the factors contributing to progression, in particular the role of the immune infiltrate is needed, but studies have been hindered by the lack of low-grade glioma mouse models. We utilized transgenic mice with a cre-activatable (CA) allele of BRAF V600E to generate endogenous models for low-grade gliomas. We found that BRAF V600E expression cooperates with hemizygous CDKN2A deletion to induce low-grade gliomas, with tumors forming at a greater latency than by homozygous deletion. Cell line derivatives from low-grade lesions continue to grow slower upon orthotopic injection than those we previously derived from high-grade tumors. Murine LGG can progress to higher grade tumors within the mouse lifespan and we observe exomic changes and alterations in the tumor immune infiltrate associated with progression, the details of which will be discussed at the meeting. High-grade cells’ phenotypic changes within in vivo passage are accompanied by exomic changes. The high-grade glioma immune infiltrate is altered by dual MAPK pathway inhibition with dabrafenib and trametinib. Adding dual immune checkpoint inhibition by anti-PD-L1 and anti-CTLA-4 antibodies significantly extends survival of dabrafenib-trametinib dual treatment. Human BRAF V600E mutant tumors reportedly have a higher tumor immune infiltrate than that of BRAF wildtype gliomas, consistent with our murine RESULTS: Here we present a novel model for BRAF V600E mutant gliomas in mice that has a frequent rate of progression, similar to human BRAF V600E mutant gliomas, and an active immune infiltrate in high grade tumors which makes them susceptible to the immunostimulatory effects of dual checkpoint inhibition.

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