FGFR3 Mutations Research Articles

PATH-37. A NEW SUBTYPE OF DIFFUSE MIDLINE GLIOMA, H3 K27 AND BRAF/FGFR1 CO-ALTERED, EXHIBITS SPECIFIC BIOLOGICAL CHARACTERISTICS AND NEW THERAPEUTIC VULNERABILITIES

Abstract Diffuse midline gliomas (DMG) H3 K27-altered are incurable grade 4 gliomas and represent a major challenge in neuro-oncology. This tumor type is classified in four subtypes by the 2021 edition of the WHO Classification of the Central Nervous System tumors. However, we recently identified a new subtype of DMG by assembling a retrospective cohort of 60 adult and pediatric DMG cases harboring BRAF or FGFR1 mutations in addition to the H3K27M mutation or EZHIP overexpression. Comprehensive clinical, histological, radiological, and genomic, analyses allowed to identify distinct genotype-phenotype characteristics. Contrary to other DMG, these tumors occur more frequently in the thalamus (27% vs. 70% for BRAFV600E or 58% for FGFR1MUT), and in adults in the case of FGFRMUT tumors. Importantly, these patients display a longer overall survival with a median above three years. Unsupervised analysis of DNA methylation profiles regrouped these MAPK-altered DMG in a methylation cluster distinct from other DMG H3K27, but also lower-grade midline tumors driven by FGFR1 or BRAF mutations Additionally, this new DMG subtype harbors atypical radiological and histopathological profiles with calcification and/or a solid tumor component both for BRAFV600E and FGFR1MUT cases that can suggest this differential diagnosis. Further analyses of the transcriptome of these tumors compared to canonical DMG H3K27-altered showed an expression signature of senescence with activation of a TP53/CDKN1A axis, together with a strong upregulation of the PI3K/AKT/MTOR pathway. Our current modelling of the drug response using patient-derived models of these specific DMG will permit to rapidly prioritize treatment strategies. Additionally, our clinical experience in treating these patients suggests a higher response to everolimus and imipridone ONC201 in this specific subtype. In conclusion, DMG H3 K27 and BRAF/FGFR1 co-altered, represent a new subtype of DMG with distinct specific characteristics compared to canonical DMG H3K27 and data accumulated strongly support their separate stratification in clinical trials and specific therapeutic managements.

PATH-45. TREATMENT OF FGFR1 – ALTERED WHO GRADE 1 GLIONEURONAL TUMORS WITH FGFR INHIBITOR ERDAFITINIB

Abstract INTRODUCTION Low-grade mitogen-activated protein kinase (MAPK) pathway-altered glioneuronal tumors carry distinct molecular alterations, which may represent therapeutic opportunities to avoid or delay toxic treatments like radiation. Erdafitinib is a pan-FGFR tyrosine kinase inhibitor, regulatorily approved in recurrent urothelial carcinoma, and is under clinical investigation for recurrent FGFR-altered gliomas (NCT05859334). METHODS We report two patients with FGFR1-altered rosette-forming glioneuronal tumors (RGNT) treated with erdafitinib. RESULTS Patient 1 is a 32-year-old woman who presented with obstructive hydrocephalus and a non-enhancing pineal tumor. She underwent a subtotal resection, with histopathology initially consistent with a low grade dysembryoplastic neuroepithelial tumor. She was under observant management for 7 years, and developed worsening symptoms with slow non-enhancing growth, although stable per RANO low grade criteria. The initial tissue was sent for next-generation sequencing (NGS) and DNA methylation profiling, revealing an FGFR1 pathogenic variant with DNA methylation profiling matching with RGNT. Patient began Erdafitinib 8 mg daily, and had stable disease per RANO at 6 months. She developed CTCAE grade 1 toxicities of subretinal fluid, fatigue, dry skin, and paronychia. Patient 2 is a 34-year-old man diagnosed 1 year prior with a tectal tumor, who underwent biopsy due to non-measurable/ non-enhancing progression. Histopathology was consistent with RGNT. NGS revealed FGFR1 mutation, PIK3CA mutation, and NF1 pathogenic variant, described in the literature as characteristic of RGNT. There was insufficient tissue for DNA methylation profiling. Patient started erdafitinib 8 mg daily and remains clinically stable for 1 month. He developed asymptomatic hyperphosphatemia (CTCAE grade 1). Both patients have tolerated treatment without interruptions or dose reductions. CONCLUSION Erdafitinib is a well-tolerated and potentially efficacious treatment of FGFR1- altered RGNT, and may avoid the need for radiation. Diagnosis of MAPK- altered low-grade glioneuronal tumors, specifically RGNT, is increasingly reliant on molecular data, and can significantly impact treatment options.

Primary hepatic alpha-fetoprotein-producing neuroendocrine neoplasm harboring FGFR2 and TP53 mutations: a case report and literature review.

This report presents a rare case of a 45-year-old man diagnosed with a primary hepatic alpha-fetoprotein-producing neuroendocrine neoplasm, a condition rarely reported in the literature. The patient presented with initial symptoms of back and epigastric pain, after which multiple liver lesions were discovered on contrast-enhanced computed tomography, suggesting intrahepatic cholangiocarcinoma. Histopathological and immunohistochemical analyses confirmed the diagnosis of alpha-fetoprotein-producing neuroendocrine neoplasm that was further supported by genetic testing, which revealed FGFR2 and TP53 mutations commonly encountered in intrahepatic cholangiocarcinoma. Despite receiving various chemotherapeutic regimens, the patient exhibited a progressive disease. This case underscores the importance of accurate differential diagnosis from hepatocellular carcinoma and intrahepatic cholangiocarcinoma due to differences in treatment approaches and prognoses and highlights the necessity for increased awareness of AFP-producing primary hepatic neuroendocrine neoplasms among clinicians and pathologists. It emphasizes the significance of comprehensive histopathological evaluation, immunohistochemical profiling, and genetic analysis for precise diagnosis and tailored therapeutic strategies. Further research is warranted to elucidate the molecular mechanisms underlying this rare liver tumor subtype and develop targeted treatments.

Pre-treatment metastatic biopsy: a step towards precision oncology for urothelial cancer.

Early metastatic spread and clonal expansion of individual mutations result in a heterogeneous tumour landscape in metastatic urothelial cancer (mUC). Substantial molecular heterogeneity of common drug targets, such as membranous NECTIN4, FGFR3 mutations, PDL1 or immune phenotypes, has been documented between primary and metastatic tumours. However, translational and clinical studies frequently do not account for such heterogeneity and often investigate primary tumour samples that might not be representative in patients with mUC. We propose this as a potential factor for why many biomarkers for mUC have failed to be integrated into clinical practice. Fresh pre-treatment metastatic biopsies enable the capturing of prevailing tumour biology in real time. The characterization of metastatic tumour samples can improve response prediction to immunotherapy, the anti-NECTIN4 antibody-drug conjugate enfortumab vedotin and the FGFR inhibitor erdafitinib. Routine metastatic biopsy can thus improve the precision of identifying driver druggable alterations, thus improving treatment selection for patients with mUC.

The Clinical and Molecular Landscape of Rosette-Forming Glioneuronal Tumors.

Rosette-Forming Glioneuronal Tumors (RGNTs) are rare, typically benign central nervous system tumors primarily located in the fourth ventricle and pineal region. Despite being classified as WHO grade I with generally favorable prognoses, RGNTs present complexities in their molecular mechanisms, occasional malignant transformation, and epidemiological characteristics that require further investigation. This study systematically reviews the existing literature to analyze the epidemiological patterns, MRI characteristics, pathological features, diagnostic challenges, and molecular mechanisms associated with RGNTs, aiming to provide a comprehensive theoretical foundation for clinical practice and future research. Through an in-depth review of recent studies, key molecular mechanisms, including mutations in FGFR1, PIK3CA, TERT, and IDH1/2, are highlighted. Additionally, the challenges in accurate diagnosis and the potential for misdiagnosis are discussed, emphasizing the importance of thorough molecular analysis in clinical settings. The literature indicates that RGNTs predominantly affect young adults and adolescents, with a slight female predominance. MRI typically reveals mixed cystic-solid lesions, often accompanied by hydrocephalus. Pathologically, RGNTs are characterized by a combination of neuronal and glial components, with immunohistochemical staining showing positivity for Synaptophysin and GFAP. High frequencies of FGFR1 and PIK3CA mutations underscore the significance of these pathways in RGNT pathogenesis and progression. Although RGNTs generally exhibit low malignancy, the TERT mutations identified in some cases suggest a risk of malignant transformation. This study concludes that while current treatment strategies focus on surgical resection, integrating molecular diagnostics and targeted therapies may be essential for managing recurrent or refractory RGNTs. Future research should explore the impact of various gene mutations on tumor behavior and their correlation with clinical outcomes, to optimize individualized therapeutic strategies and improve patient survival and quality of life.

7407 Normosmic Idiopathic Hypogonadotropic Hypogonadism in Women: A Case Report and Comprehensive Review

Abstract Disclosure: E.G. Bustamante: None. M. Sulehri: None. I. Patoli: None. A. Karunakaran: None. Normosmic Idiopathic Hypogonadotropic Hypogonadism (nIHH) in Women: A Case Report and Literature ReviewIntroduction: IHH is a rare genetic disorder affecting gonadotropic-releasing hormone (GnRH) production and/or action, resulting in diminished sex steroid levels. Characterized by the absence of spontaneous pubertal development. In women, it manifests with normal adrenarche but absent thelarche and menarche. Our case highlight a late diagnosis of IHH in a 34-year-old woman with primary amenorrhea. Case report: A 34 year old lady with a history of primary amenorrhea sought evaluation. At age 16, she underwent assessment for short stature and primary amenorrhea, denying anosmia, headache, visual disturbances. Evaluation revealed bone age concordant with chronological age and normal MRI Brain. Pelvic ultrasound (US) showed small premenarchal uterus and ovaries. She initiated oral contraceptive pills (OCP) and experienced regular menses. Seeking fertility assistance at age 24, a normal Hysterosalpingogram was followed by successful delivery of twins after ovarian stimulation. Post-delivery menses did not resume and OCP was not restarted. Family history revealed a sister with irregular periods requiring OCP.Subsequently workup at age 30 showed Estradiol 22 pg/ml, FSH/LH 4.1/2.3 mUI/mL; normal PRL, TFT, DHEAS, 17OHP. Repeat Pelvic US showed normal uterus, endometrial stripe normal at 0.24 cm and non-visualized ovaries. PCOS testing negative for hyperandrogenism. Progesterone challenge resulted in no withdrawal bleeding. Brain MRI demonstrated a 2.2 x 1.3 mm hypoenhancing ovoid mass in the pars Intermedia of the pituitary gland suggestive of pituitary microadenoma. Pituitary axis hormonal testing was normal. Karyotype revealed 46 XX (normal female). Genetic evaluation identified a pathogenic variant (p.R35C) in GNRH1 gene. Her final diagnosis: nIHH. Discussion HH is diagnosed in 5% of all women with primary amenorrhea and is divided into 2 major categories: Kallmann syndrome and nIHH. The majority of known causes of HH can be attributed to mutations in KAL1, FGFR1, or GNRHR. The p.R35C variant has been associated with autosomal dominant nIHH. Diagnosis involves clinical suspicious, low LH/FSH and sex steroid levels, normal hypothalamic–pituitary imaging, and exclusion of differentials.Treatment goal for female focus on regular breast and uterine development, as well as the capability to conceive. Use of hormonal replacement therapy and/or gonadotropins or pulsatile GnRH for ovarian stimulation are essential. ConclusionWhile IHH predominantly affects men, limited literature explores its manifestation in women and its impact on fertility. The identification of a GNRH1-related nIHH variant highlights the role of genetic testing in specific HH diagnoses. Failure to diagnose in adolescence may compromise women overall well-being Presentation: 6/1/2024

Discovery of TYRA-300: First Oral Selective FGFR3 Inhibitor for the Treatment of Urothelial Cancers and Achondroplasia.

Activating FGFR3 alterations have been identified in up to 15-20% of muscle-invasive bladder cancer and metastatic urothelial carcinoma (mUC), and as high as 80% in nonmuscle invasive bladder cancers. FGFR3 germline mutations have also been associated with a variety of skeletal dysplasias. Achondroplasia, the most common form of dwarfism in humans, results from a G380R mutation in FGFR3. The pan-FGFR inhibitor erdafitinib was approved for the treatment of mUC with FGFR3 alterations but is limited due to FGFR isoform off-target toxicities and the development of on-target gatekeeper resistance mutations. TYRA-300 (22) was conceived using a structure-based approach as a potent FGFR3-selective inhibitor to avoid the toxicities associated with inhibition of FGFR1, FGFR2, and FGFR4, and to be agnostic for the FGFR3 gatekeeper mutations. TYRA-300 is being evaluated in a Phase 1 clinical trial in urothelial cancers and solid tumors, with intention to initiate Phase 2 studies in urothelial cancers and achondroplasia.

MTAP protein status is highly concordant with CDKN2A fluorescent in situ hybridization and allows stratification of the luminal subtype in muscle-invasive bladder cancer.

Loss of heterozygosity in chromosome 9p21, common in urothelial carcinoma (UC), typically involves deletion of CDKN2A and MTAP genes. MTAP loss is emerging as a promising therapeutic target and predictive biomarker in UC. This single-centrre retrospective study examined the incidence of CDKN2A deletions and MTAP loss in muscle-invasive bladder cancer (MIBC) and metastatic urothelial carcinoma (mUC), investigating their correlations with clinical, pathological, and genomic features, as well as patient outcomes. Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) were performed on 302 MIBC specimens and 63 biopsy-proven metachronous urothelial metastases to assess CDKN2A deletions and MTAP protein expression. CDKN2A homozygous deletion (HD), identified in 30.3% of MIBCs, and MTAP loss, found in 28.8% of MIBCs, were both significantly associated with the luminal-URO subtype, FGFR3 mutations, and normal/wildtype p53 IHC (P < 0.05). Loss of MTAP expression was significantly correlated with CDKN2A HD, with 84.0% sensitivity, 92.3% negative predictive value (NPV), 96.3% specificity, and 91.9% positive predictive value (PPV). MTAP expression was 100% concordant between primary tumours and nodal metastases. Patients with MTAP loss had a higher incidence of visceral metastases (50%) compared to bone/soft tissue (35.7%) and nodes (14.3%). Mean progression-free survival and overall survival were shorter for patients with MTAP loss, although not statistically significant. Our findings highlight CDKN2A HD and MTAP loss as prevalent genetic alterations in MIBC and mUC, particularly within the luminal-URO subtype and FGFR3-mutated, p53-normal/wildtype tumours. MTAP IHC can serve as a surrogate marker for 9p21.3 HD, highlighting its clinical relevance and potential as a therapeutic target and predictive biomarker in MIBC.

Abstract C083: Meta-analysis reveals differences in somatic alterations by genetic ancestry across common cancers

Abstract Genetic similarity of populations (or genetic ancestry) contributes to cancer driving alterations. We performed a meta-analysis leveraging two real-world cohorts of targeted gene panel sequencing, comprising 275,605 tumor samples, to investigate ancestry-associated somatic alterations across 14 common cancers. We focused on five continental ancestries – European (EUR), African (AFR), East Asian (EAS), South Asian (SAS), and admixed American (AMR). Genetic ancestry was inferred using single nucleotide polymorphism markers from captured regions of gene panel sequencing in each cohort. The combined cohort from Memorial Sloan Kettering – Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) and Foundation Medicine (FMI) contains a substantial number (45,131) of non-EUR samples. Within each cohort, we performed multivariate logistic regression to test association of each cancer gene alteration with proportion of genetic ancestry as a continuous variable, controlling for relevant covariates (age, sex, gene panel version, and histological subtypes) for every combination of ancestry and cancer type. Our analysis focused on oncogenic or likely oncogenic alterations spanning mutations, copy number alterations, and structural rearrangements for each gene. We then aggregated the logistic regression results from the two cohorts using a fixed effects model of meta-analysis weighted by cohort sample size. We found 444 significant associations involving 116 unique genes with consistent logistic regression coefficients between cohorts and False Discovery Rate (FDR)-adjusted p-value &amp;lt; 0.1. These genes were involved in cancer-specific and cross-cancer associations. TP53, KRAS, and TERT were the top three recurrent ancestry-associated genes respectively. TERT promoter mutations were depleted in patients of AFR or EAS ancestry, but enriched in EUR ancestry in bladder urothelial carcinoma, glioblastoma, cutaneous melanoma, and hepatocellular carcinoma. Additionally, TP53 mutations were enriched in AFR and EAS ancestry across multiple cancers, consistent with previous reports, but depleted in prostate cancer in both AFR and EAS ancestries. Among the novel cancer-specific associations with FDA-approved targeted therapies, we found that CDK12 mutations in prostate adenocarcinoma were enriched in EAS ancestry while ERBB2 mutations in lung adenocarcinoma were enriched in AMR ancestry. We also found novel potential drug targets/biomarkers associated with AFR ancestry, such as enrichment of BAP1 mutations in head and neck squamous cell carcinoma and depletion of FGFR2 mutations in uterine endometrioid carcinoma. Overall, our work identified ancestry-associated somatic alteration differences of cancer genes in a combined cohort with a large number of non-European samples. This work underscores the value of studying under-represented populations to replicate or reveal new potential targets for precision oncology. Citation Format: Setor Amuzu, Amy Xie, Xuechun Bai, Kelly R. Pekala, David Ma, Tomin Perea-Chamblee, Kanika Aurora, Garrett Frampton, Michael Berger, Nikolaus Schultz, Justin Y. Newberg, Jian Carrot-Zhang. Meta-analysis reveals differences in somatic alterations by genetic ancestry across common cancers [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C083.

Racial and Sex Differences in Genomic Profiling of Intrahepatic Cholangiocarcinoma

BackgroundRacial and sex disparities in the incidence and outcomes of patients with intrahepatic cholangiocarcinoma (iCCA) exist, yet potential genomic variations of iCCA based on race and sex that might be contributing to disparate outcomes have not been well studied.MethodsData from the American Association for Cancer Research Project GENIE registry (version 15.0) were analyzed to assess genetic variations in iCCA. Adult patients (age >18 years) with histologically confirmed iCCA who underwent next-generation sequencing were included in the analytic cohort. Racial and sex variations in genomic profiling of iCCA were examined.ResultsThe study enrolled 1068 patients from 19 centers (White, 71.9%; Black, 5.1%; Asian, 8.4%, other, 14.6%). The male-to-female ratio was 1:1. The majority of the patients had primary tumors (73.7%), whereas 23.0% had metastatic disease sequenced. While IDH1 mutations occurred more frequently in White versus Black patients (20.8% vs. 5.6%; p = 0.021), FGFR2 mutations tended to be more common among Black versus White populations (27.8% vs. 16.1%; p = 0.08). Males were more likely to have TP53 mutations than females (24.3% vs. 18.2%, p = 0.016), whereas females more frequently had IDH1 (23.3% vs 16.0 %), FGFR2 (21.0% vs. 11.3%), and BAP1 (23.4% vs. 14.5%) mutations than males (all p < 0.05). Marked variations in the prevalence of other common genomic alterations in iCCA were noted across different races and sexes.ConclusionDistinct genomic variations exist in iCCA across race and sex. Differences in mutational profiles of iCCA patients highlight the importance of including a diverse patient population in iCCA clinical trials as well as the importance of recognizing different genetic drivers that may be targetable to treat distinct patient cohorts.

Distinct phenotypic consequences of cholangiocarcinoma-associated FGFR2 alterations depend on biliary epithelial maturity.

Epithelial cancers disrupt tissue architecture and are often driven by mutations in genes that normally play important roles in epithelial morphogenesis. The intrahepatic biliary system is an epithelial tubular network that forms within the developing liver via the de novo initiation and expansion of apical lumens. Intrahepatic biliary tumors are often driven by different types of mutations in the FGFR2 receptor tyrosine kinase which plays important roles in epithelial morphogenesis in other developmental settings. Using a physiologic and quantitative 3D model we have found that FGFR signaling is important for biliary morphogenesis and that oncogenic FGFR2 mutants disrupt biliary architecture. Importantly, we found that both the trafficking and signaling of normal FGFR2 and the phenotypic consequences of FGFR2 mutants are influenced by the epithelial state of the cell. Unexpectedly, we found that different tumor-driving FGFR2 mutants disrupt biliary morphogenesis in completely different and clinically relevant ways, informing our understanding of morphogenesis and tumorigenesis and highlighting the importance of convergent studies of both.

Long-term survivors in 976 supratentorial glioblastoma, IDH-wildtype patients.

Glioblastoma, isocitrate dehydrogenase (IDH)-wildtype is the most aggressive glioma with poor outcomes. The authors explored survival rates and factors associated with long-term survival in patients harboring a glioblastoma, IDH-wildtype. In an observational, retrospective, single-center study, the authors examined the medical records of 976 adults newly diagnosed with supratentorial glioblastomas, IDH-wildtype between January 2000 and January 2021. They analyzed clinical-, imaging-, and treatment-related factors associated with 2-year and 5-year survival. The median overall survival was 11.2 months (12.2 months for patients included after 2005 and the introduction of standard combined chemoradiotherapy). The median progression-free survival was 9.4 months (10.0 months for patients included after 2005). Overall, 17.6% of patients reached a 2-year overall survival, while 2.2% of patients reached a 5-year overall survival. Furthermore, 6.6% of patients survived 2 years without progression, while 1.1% of patients survived 5 years without progression. Two factors that were consistently associated with 2-year and 5-year survival were first-line oncological treatment with standard combined chemoradiotherapy and methylated O6-methylguanine-DNA methyltransferase promoter. Other factors that were significantly associated with 2-year or 5-year survival were age at diagnosis ≤ 60 years, headaches or signs of raised intracranial pressure at diagnosis, cortical contact of contrast enhancement, no contrast enhancement crossing the midline on initial imaging, total or subtotal tumor resection, and a second line of oncological treatment at recurrence. Within 21 cases of 5-year survival, 18 were confirmed to be glioblastomas, IDH-wildtype, and 7 of the 5-year survivors (38.9%) had additional genetic alterations: 3 cases had an FGFR mutation or fusion, 3 cases had a PIK3CA mutation, 1 case had a PTPN11 mutation, and 1 case had a PMS2 mutation in the context of constitutional mismatch repair deficiency syndrome. Five-year overall survival in patients with glioblastoma, IDH-wildtype is extremely low. Predictors of a longer survival are mostly treatment factors, emphasizing the importance of a complete oncological treatment plan, when achievable. Glioblastoma, IDH-wildtype 5-year survivors could be screened for actionable targets in case of recurrence.

Neuroradiological, genetic and clinical characteristics of histone H3 K27-mutant diffuse midline gliomas in the Kansai Molecular Diagnosis Network for CNS Tumors (Kansai Network): multicenter retrospective cohort

This study aims to elucidate the clinical and molecular characteristics, treatment outcomes and prognostic factors of patients with histone H3 K27-mutant diffuse midline glioma. We retrospectively analyzed 93 patients with diffuse midline glioma (47 thalamus, 24 brainstem, 12 spinal cord and 10 other midline locations) treated at 24 affiliated hospitals in the Kansai Molecular Diagnosis Network for CNS Tumors. Considering the term “midline” areas, which had been confused in previous reports, we classified four midline locations based on previous reports and anatomical findings. Clinical and molecular characteristics of the study cohort included: age 4–78 years, female sex (41%), lower-grade histology (56%), preoperative Karnofsky performance status (KPS) scores ≥ 80 (49%), resection (36%), adjuvant radiation plus chemotherapy (83%), temozolomide therapy (76%), bevacizumab therapy (42%), HIST1H3B p.K27M mutation (2%), TERT promoter mutation (3%), MGMT promoter methylation (9%), BRAF p.V600E mutation (1%), FGFR1 mutation (14%) and EGFR mutation (3%). Median progression-free and overall survival time was 9.9 ± 1.0 (7.9–11.9, 95% CI) and 16.6 ± 1.4 (13.9–19.3, 95% CI) months, respectively. Female sex, preoperative KPS score ≥ 80, adjuvant radiation + temozolomide and radiation ≥ 50 Gy were associated with favorable prognosis. Female sex and preoperative KPS score ≥ 80 were identified as independent good prognostic factors. This study demonstrated the current state of clinical practice for patients with diffuse midline glioma and molecular analyses of diffuse midline glioma in real-world settings. Further investigation in a larger population would contribute to better understanding of the pathology of diffuse midline glioma.

Genotype-relevant neuroimaging features in low-grade epilepsy-associated tumors.

Low-grade epilepsy-associated tumors are the second most common histopathological diagnoses in cases of drug-resistant focal epilepsy. However, the connection between neuroimaging features and genetic alterations in these tumors is unclear, prompting an investigation into genotype-relevant neuroimaging characteristics. This study retrospectively analyzed neuroimaging and surgical specimens from 46 epilepsy patients with low-grade epilepsy-associated neuroepithelial tumors that had genetic mutations identified through panel sequencing to investigate their relationship to genotypes. Three distinct neuroimaging groups were established: Group 1 had indistinct borders and iso T1-weighted and slightly high or high T2-weighted signal intensities without a diffuse mass effect, associated with 93.8% sensitivity and 100% specificity to BRAF V600E mutations; Group 2 exhibited sharp borders and very or slightly low T1-weighted and very high T2-weighted signal intensities with a diffuse mass effect and 100% sensitivity and specificity for FGFR1 mutations; and Group 3 displayed various characteristics. Histopathological diagnoses including diffuse low-grade glioma and ganglioglioma showed no clear association with genotypes. Notably, postoperative seizure-free rates were higher in Group 1 tumors (BRAF V600E) than in Group 2 tumors (FGFR1). These findings suggest that tumor genotype may be predicted by neuroimaging before surgery, providing insights for personalized treatment approaches.

The Impact of Fibroblast Growth Factor Receptor Alterations in Clinical Outcomes of Patients With Advanced Urothelial Carcinoma: Real-World Data From a Latin American Population

IntroductionFibroblast growth factor receptor (FGFR) mutations and fusions are relevant biomarkers in metastatic urothelial carcinoma (mUC). However, the prevalence of genomic alterations and their impact on clinical outcomes in a Latin American population remains unknown. This study aimed to explore the prevalence of FGFR mutations and/or fusions in patients with mUC in Latin America (LATAM) and its association with clinicopathological characteristics, Bellmunt's prognostic model, and survival outcomes. Patients and methodsA multicenter retrospective cohort study from 2016 to 2019 of patients with mUC from several LACOG LATAM institutions. FGFR alterations were analyzed by real-time PCR and/or next-generation sequencing in tumor samples and clinicopathologic characteristics and survival outcomes data were collected. The prevalence of FGFR, patient characteristics, and treatment in real-world settings were summarized. Kaplan-Meier survival estimates and Cox regression analyses were used to evaluate the associations of FGFR mutation and/or fusion status with median overall survival (mOS), median time to treatment failure (mTTF), and clinicopathological characteristics. ResultsIn total, 222 patients were screened. Of these, 196 patients were considered eligible and were included in the analysis. FGFR mutations and/or fusions were found in 35 (17.9%) patients. There was no statistical difference in mOS and mTTF in FGFR-altered and non-altered patients (13.1 vs. 16.8 months, P = .20 and 3.9 vs. 4.1 months, P = .96, respectively). Bellmunt's prognostic model correctly predicted overall survival (P = .049). ConclusionsThis is the largest study evaluating the prevalence of FGFR alterations in patients with mUC in the LATAM population. FGFR alterations in mUC were found in 17.9% of the patients, and the presence of this biomarker was not associated with OS. We validated Bellmunt's prognostic model in this cohort.

Real-world performance of Uromonitor® in urothelial bladder cancer detection: a multicentric trial.

To compare Uromonitor® (U-Monitor Lda, Porto, Portugal), a multitarget DNA assay that detects mutated proto-oncogenes (telomerase reverse transcriptase [TERT], fibroblast growth factor receptor 3 [FGFR-3], Kirsten rat sarcoma viral oncogene homologue [KRAS]), with urine cytology in the urine-based diagnosis of urothelial carcinoma of the bladder (UCB) within a multicentre real-world setting. This multicentre, prospective, double-blind study was conducted across four German urological centres from 2019 to 2024. We evaluated the diagnostic performance of Uromonitor compared to urine cytology in a cohort of patients with UCB and in healthy controls within a real-world setting. Sensitivity, specificity, positive-predictive value (PPV), negative-predictive value (NPV), and accuracy of the tests were measured, in addition to multivariate analyses to assess the ability of individual proto-oncogene mutations in detecting UCB. The biometric sample size was designed to achieve a 10% difference in sensitivity. Patients with UCB comprised 63.7% (339/532) of the study group. Uromonitor showed a sensitivity, specificity, PPV, NPV, accuracy, and an area-under-the-curve of 49.3%, 93.3%, 92.8%, 51.1%, 65.2%, and 0.713%, respectively. These metrics did not demonstrate statistical superiority over urine cytology in terms of sensitivity (44.6%; P = 0.316). Moreover, the comparison of additional test parameters, as well as the comparison within various sensitivity analyses, yielded no significant disparity between the two urinary tests. Multivariate logistic regression underscored the significant predictive value of a positive Uromonitor for detecting UCB (odds ratio [OR] 9.03; P < 0.001). Furthermore, mutations in TERT and FGFR-3 were independently associated with high odds of UCB detection (OR 13.30 and 7.04, respectively), while KRAS mutations did not exhibit predictive capability. Despite its innovative approach, Uromonitor fell short of confirming the superior results anticipated from previous studies in this real-world setting. The search for an optimal urine-based biomarker for detecting and monitoring UCB remains ongoing. Results from this study highlight the complexity of developing non-invasive diagnostic tools and emphasise the importance of continued research efforts to refine these technologies.

FGF signaling modulates mechanotransduction/WNT signaling in progenitors during tooth root development

Stem/progenitor cells differentiate into different cell lineages during organ development and morphogenesis. Signaling pathway networks and mechanotransduction are important factors to guide the lineage commitment of stem/progenitor cells during craniofacial tissue morphogenesis. Here, we used tooth root development as a model to explore the roles of FGF signaling and mechanotransduction as well as their interaction in regulating the progenitor cell fate decision. We show that Fgfr1 is expressed in the mesenchymal progenitor cells and their progeny during tooth root development. Loss of Fgfr1 in Gli1+ progenitors leads to hyperproliferation and differentiation, which causes narrowed periodontal ligament (PDL) space with abnormal cementum/bone formation leading to ankylosis. We further show that aberrant activation of WNT signaling and mechanosensitive channel Piezo2 occurs after loss of FGF signaling in Gli1-CreER;Fgfr1fl/fl mice. Overexpression of Piezo2 leads to increased osteoblastic differentiation and decreased Piezo2 leads to downregulation of WNT signaling. Mechanistically, an FGF/PIEZO2/WNT signaling cascade plays a crucial role in modulating the fate of progenitors during root morphogenesis. Downregulation of WNT signaling rescues tooth ankylosis in Fgfr1 mutant mice. Collectively, our findings uncover the mechanism by which FGF signaling regulates the fate decisions of stem/progenitor cells, and the interactions among signaling pathways and mechanotransduction during tooth root development, providing insights for future tooth root regeneration.

Computational biophysical characterization of the effect of gatekeeper mutations on the binding of ponatinib to the FGFR kinase

Fibroblast Growth Factor Receptor (FGFR) is connected to numerous downstream signalling cascades regulating cellular behavior. Any dysregulation leads to a plethora of illnesses, including cancer. Therapeutics are available, but drug resistance driven by gatekeeper mutation impedes the treatment. Ponatinib is an FDA-approved drug against BCR-ABL kinase and has shown effective results against FGFR-mediated carcinogenesis. Herein, we undertake molecular dynamics simulation-based analysis on ponatinib against all the FGFR isoforms having Val to Met gatekeeper mutations. The results suggest that ponatinib is a potent and selective inhibitor for FGFR1, FGFR2, and FGFR4 gatekeeper mutations. The extensive electrostatic and van der Waals interaction network accounts for its high potency. The FGFR3_VM mutation has shown resistance towards ponatinib, which is supported by their lesser binding affinity than wild-type complexes. The disengaged molecular brake and engaged hydrophobic spine were believed to be the driving factors for weak protein-ligand interaction. Taken together, the inhibitory and structural characteristics exhibited by ponatinib may aid in thwarting resistance based on Val-to-Met gatekeeper mutations at an earlier stage of treatment and advance the design and development of other inhibitors targeted at FGFRs harboring gatekeeper mutations.

LGG-12. INTEGRATED CLINICAL AND MOLECULAR CHARACTERIZATION OF 200 DISSEMINATED PEDIATRIC LOW-GRADE GLIOMAS

Abstract Pediatric low-grade gliomas (PLGG) have excellent outcomes overall but are a major clinical challenge when disseminated. Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a recognised entity both clinically and pathologically, however many disseminated LGG (DLGG) fall outside this diagnosis. To better understand the clinical and molecular features of DLGG as well as risk factors for dissemination, we assembled an international consortium of 30 sites, contributing over 200 patients with clinical annotation, along with genomic and methylation profiling. DLGG have worse progression-free (PFS) and overall survival (OS) than PLGG overall (p&amp;lt;0.0001). Seventy (35%) presented with a localized mass and secondary dissemination, including some with initial gross-total resection. The most common growth pattern observed (n=77, 40%) is a dominant suprasellar/optic pathway tumor with leptomeningeal drop-metastases involving the brainstem and spinal cord. Only 27 (14%) patients had diffuse tumors (without an identifiable dominant mass), and these had significantly worse OS (p=0.03). The most common pathologic diagnosis was pilocytic/pilomyxoid astrocytoma (n=92; 53%). DLGNT comprised a minority of cases (n=23, 14%), with a trend (p=0.056) towards worse survival compared to other diagnoses. The most frequent molecular alteration was BRAF fusion (78/151 with molecular testing; 52%), followed by FGFR mutations or fusions (18/151; 12%). BRAF V600E was underrepresented (14/151; 9%). 1p deletion was rare (17 patients) but highly associated with DLGNT. Methylation classification (n=70) was highly concordant with histologic diagnoses rather than clinical behavior. Importantly, patients who received upfront targeted therapies (TT; BRAF and/or MEK inhibition, n=9) had better PFS compared to those receiving chemotherapy (n=146, p=0.05). Furthermore, patients who were treated sequentially with chemo then TT had longer PFS on TT (p=0.011). This study presents the largest cohort of DLGG to date, expanding our understanding of the clinical, pathologic, and molecular features of this disease and supports the use of upfront targeted therapy.

LGG-34. THE LANDSCAPE OF GLIOMAS IN CHILDREN, ADOLESCENTS AND YOUNG ADULTS REVEALS INSIGHTS ON GLIOMAGENESIS: A CANADIAN ADOLESCENTS AND YOUNG ADULTS NEURO-ONCOLOGY NETWORK (CANON) STUDY

Abstract BACKGROUND Gliomas are a heterogenous and common cancer in children, adolescents and young adults (CAYA, ages 0-39 years). Little is known about the biologic and clinical implications of gliomas in AYA limiting our ability to appropriately manage these patients. METHODS We compiled a population-based cohort of patients with glioma aged 0-39 years diagnosed between 2000-2020, performed molecular characterization of the tumors and collected clinical data including therapy and long-term outcome. RESULTS A total of 1456 patients, including 873 AYA patients were included. A pathogenic molecular alteration was found in 98% of AYA samples available. Strikingly, pediatric-type mutations were found in 31% of AYA glioma of which 37% were BRAF V600E and 23% FGFR alterations. Important differences were observed between gliomas in children versus AYAs. First, hemispheric tumors were enriched in AYAs compared to midline tumors in children, especially for RAS/MAPK alterations. Second, increased incidence of high grade tumors in AYA compared to children were observed for BRAF V600E and FGFR mutations (p&amp;lt;0.0001). In contrast, if these alterations were identified in AYA and the tumor was low grade, outcome was improved for BRAF V600E and FGFR mutant tumors in AYAs compared to pediatrics (for BRAF V600E 5 year PFS 55.6% &amp;lt;10 years, 78.1% for 10-20 years and 87.1% for 10-20 years of age, p=0.0002). Third, a specific time window for transformation was observed for each alteration (BRAF, FGFR, IDH). This correlated with different methylation profiles and transcriptional patterns between early midline and late hemispheric tumors. Increased senescence signatures were observed in older patients with low grade RAS/MAPK driven tumors with superior outcome. CONCLUSIONS Different cell of origin and secondary mutations shape tumor behavior and lead to either transformation or senescence during gliomagenesis in CAYA. These can affect early interventions and tailored approaches for gliomas by age and molecular alteration.