Abstract
BACKGROUND
Liquid biopsy has gained popularity of late in the diagnosis and management of several cancers. This study aims to diagnose suspected lesions suspected of being gliomas on ...neuro-imaging by obtaining a peripheral venous blood sample- with a specificity and sensitivity that approaches a tissue biopsy. MATERIALS AND
METHODS
After clearance from Ethics Committees, specimens of the tumour tissue along with blood from a peripheral or vein was collected from all 80 adult patients with a suspected diagnosis of glioma. Clinical details along with the neurological status, the functional score, the extent of resection, pathological diagnosis and survival data were also collected. The tumour tissue transported in RNA-later and stored at -80C. Following exosome isolation, RNA-seq was performed on the exosomal sample obtained from the serum and the tumour sample. Exome analysis was performed on the tumour tissue (somatic mutations) and the WBC (for germline mutations) to a depth of 100.
RESULTS
The analysed data was quality checked for all glioma associated genes including but not limited to ATRX, H3F3A, IDH1, MGTM and TERT driver genes related to DNA repair, cytoskeleton and cellular proliferation-related genes EGFR, FLT1/(VEGFR), BRAF, GFAP, MKi67, NES, OLIG2, PIK3CA, SMAD3, S1001A and VIM and tumour suppressor genes SMARCB1/INI1 and TP53. Open-source cloud based genomic analysis platforms were used for analysis. Machine learning clustering algorithms identified serum exosome based clusters that corresponded to already identified glioma tissue based genomic subgroups, with specificity and sensitivity approaching 95%.
CONCLUSION
Liquid biopsies provide a reliable and effective way of diagnosing gliomas in patients who present with an intracranial lesion on radiology.
Abstract
BACKGROUND
Treatment-related toxicity is common in patients with glioblastoma (GBM) receiving chemotherapy and radiotherapy (RT). Temporalis muscle thickness (TMT) is a biomarker associated ...with sarcopenia and worse clinical outcomes in GBM, however its relation to treatment toxicity is less studied. We hypothesize that TMT may predict toxicity and survival in GBM patients.
METHODS
We reviewed consecutive patients with IDH-wildtype GBM treated from 2014-2019 at a single academic center. TMT was retrospectively assessed on T1-weighted MRI scans and dichotomized based upon previously validated sex-specific cutoff values. TMT was measured on baseline MRI scan at time of diagnosis. Cox regression multivariable analysis (MVA) was used to assess survival.
RESULTS
We evaluated 351 patients with median age of 60y (range 20-94) and median follow-up of 14mo. Most patients were male (59%), baseline KPS >70 (95%), and MGMT unmethylated (55%). After maximal safe resection, most patients received standard (90%) or hypofractionated (10%) RT with concurrent systemic therapy (89%). On MVA, baseline low TMT (HR 1.93, p=0.01), age >65y, baseline KPS, and MGMT-unmethylated status were associated with worse OS. On MVA, baseline low TMT (HR 1.95, p=0.01), age >65y, MGMT-unmethylated status, and discontinuing systemic therapy were associated with worse profession-free survival (PFS). 21 patients did not complete anticipated treatment course of chemoradiation and adjuvant systemic therapy due to toxicity, primarily thrombocytopenia, associated with worse OS on MVA (HR 1.99, p< 0.01). Low TMT was associated with higher risk of stopping treatment due to adverse events (OR 5.25, p< 0.01) independent of age, sex, extent of resection, RT dose on MVA.
CONCLUSION
Baseline low TMT was associated with worse PFS and OS, and it was associated with treatment interruption due to treatment toxicity in GBM patients. While further validation is needed, TMT may help identify patients who will benefit from aggressive symptom management or treatment deintensification.
Abstract
Medulloblastoma is a central nervous system tumor that develops through various genetic, epigenetic, and non-coding (nc) RNA-related mechanisms, but the roles played by ncRNAs, particularly ...circular RNAs (circRNAs), remain poorly defined. CircRNAs are increasingly recognized as stable noncoding RNA therapeutic targets in many cancers, but little is known about their function, subtype specificity, and therapeutic potential in medulloblastomas. To determine medulloblastoma subgroup-specific circRNAs, we subjected RNA-seq data from 175 clinical medulloblastoma samples in four subgroups (SSH, WNT, G3, and G4) to a statistical and machine learning (random forest) pipeline and identified a group of medulloblastoma specific circular RNAs. CircRNA, circ_63706 was identified as sonic hedgehog (SHH) group specific and confirmed its expression by RNA-FISH analysis in clinical tissue samples (tissue microarrays). To identify the molecular function of circ_63706, we depleted circ_63706 in DAOY and ONS76 cells and subjected them to global RNA sequencing and lipid profiling. Circ_63706 resides in the coding gene Pericentrin (PCNT), which is known to be involved in congenital disorders. When Circ_63706 gets depleted by shRNA, it shows a significant decrease in cell proliferation and invasion in SSH cells, and mice implanted with circ_63706-deleted cells showed reduced tumor growth and extended survival compared to parental cells implant. At the molecular level, we identified circ_63706-deleted cells elevated total ceramide and oxidized lipids and reduced total triglyceride (TG). Our study implicates an identification of a novel oncogenic circular RNA in the medulloblastoma subgroup SSH and establishes its potential as a future therapeutic target.
Abstract
Glioblastoma remains a highly malignant and intrinsically resistant brain tumor. Despite intensive research through which numerous potential druggable targets were identified, virtually all ...clinical trials of the past 20 years failed to improve the outcome for the vast majority of GBM patients. However, the identification of small subgroups of patients that showed an exceptional response across several trials, implies that, when selected more carefully, some GBM patients could probably still benefit from these therapies. Identifying these patients requires that suitable biomarkers are identified. In this project, we reassessed the molecular mechanisms of ten actionable compounds (selected from previously failed trials but for which exceptional responders had been observed) in a set of carefully selected patient-derived cell lines that were sensitive/resistant to the selected therapies. Moreover, to deal with tumor heterogeneity, we used a multi-omic functional precision oncology approach, combining scRNA-seq and CyTOF, to identify drug-specific biomarkers by comparing control and treated samples at single-cell resolution. By subsequently correlating the molecular signatures to eventual cytotoxicity profiles, we could identify intrinsically responsive tumor cells at the single-cell level within hours following drug exposure. Overall, this work lays the foundation for an actionable functional diagnostic assay that could help to identify eligible GBM patients in future clinical trials.
Abstract
BACKGROUND
The molecular landscape of adult diffuse glioma has been extensively characterized by gene expression and DNA methylation profiling, but less attention has been paid to somatic ...copy number alteration (SCNA) data. This study aimed to give a rigorous, survival-focused analysis of glioma genome-wide SCNA data that builds on our previous work.
METHODS
Detailed survival analyses were conducted on the substructure of UMAP projections of all TCGA glioma (Nf1092), exclusively astrocytic glioma (Nf914), and exclusively IDH-wildtype glioma (Nf528). Results were validated with data from the Glioma Longitudinal Analysis Consortium (GLASS) (Nf224). Clinical factors such as age and MGMT methylation were tested in multivariate survival analyses.
RESULTS
A UMAP projection of TCGA glioma SCNA data generated three distinct clusters composed of entirely oligodendroglioma, predominantly IDH-mutant astrocytoma (C-IDHmut-astro), and predominantly IDH-wildtype glioma (C-IDHwt), respectively. For astrocytic tumors, cluster assignment was independently prognostic of IDH status (p< 0.001): TCGA IDH-mutant astrocytomas that clustered in C-IDHwt had poorer outcomes than their counterparts (p< 0.04) and IDH-wildtype tumors that clustered in C-IDHmut-astro fared better than those that did not (p< 0.01). The distribution of GLASS astrocytic tumors, which is skewed for better survival, supported our results in IDH-wildtype glioblastoma (p< 0.001, Fisher’s). Among four distinct subclusters of TCGA IDH-wildtype glioblastomas, the largest was significantly or marginally significantly negatively prognostic compared to each other cluster (p=0.048, p=0.059, p=0.027) and their combination (p=0.002). In the GLASS dataset, inclusion in the largest subcluster was also prognostic (p=0.013) and similar trends were observed between individual clusters (p=0.21, p=0.036, p=0.083). Furthermore, membership to the largest cluster was independently prognostic of MGMT methylation status and several published IDH-wildtype glioblastoma subtypes in the TCGA.
CONCLUSIONS
Unsupervised learning of genome-wide SCNA has prognostic implications for astrocytic glioma. SCNA cluster membership is independently prognostic of MGMT methylation status.
Abstract
Glioblastoma (GBM) has a median survival of less than 18 months with infrequent long-term survival (LTS). Reports on LTS to date have not identified distinct molecular or clinical/imaging ...characteristic in long ( >3 years) versus short (< 3 year) survivors. We identified IDH wildtype GBM patients living ≥ 3 years post diagnosis (LTS, Nf25) and a control cohort (STS, Nf76) from our Natural History Study. Available tissue was analyzed with targeted panel sequencing (Nf25) and methylation analysis (Nf21) for classification, MGMT promoter (MGMTp) status and copy number changes. Median survival and age for LTS and STS was 54mo and 48yrs, and 16mo and 56yrs, respectively. LTS were more likely to be female (2.8x) or have a GTR (2.9x) but 83% less likely to be white. MGMTp was 10x more likely to be methylated in LTS tumors (95% CI 2.6, 39.6), yet was unmethylated in 17%. LTS were 63% and 90% less likely to have TERTp or EGFR amplification (95% CI 0.14, 0.97 and 0.04, 0.29). Core pathway review showed 21% of LTS had at least one alteration in p53, RB and RTK/PI3K with RTK/PI3K the most common (46%) . Methylation classifier identified 74% as GBM (STS=96%) with most the RTK II subtype (53%; STS=41%) and despite classic histologic features, indicated a non-GBM diagnosis in three cases (14%).Although uncommon, there are LTS with molecularly confirmed GBM. Remarkably, not all had MGMTp methylation, were young or had extensive tumor resection. Clinical estimates of outcome in GBM patients should consider the possibility of long-term survival even with established poor prognostic factors. Imaging characteristics in a subset of these cases are reported in a separate abstract. Additional interrogation of tumor from LTS may uncover additional determinants of response and outcomes.
Abstract
The deregulation of canonical oncogenic pathways are largely responsible for driving pediatric cancers and can be targeted for therapeutics. Currently, we interrogate these pathways ...clinically by looking for gene mutations, but these are not found in all cases, and in others multiple genes are. We hypothesized that assessing transcriptomic and proteomic-based pathway activation will allow a better understanding of the most active oncogenic pathways and help guide therapy. To do this, we developed and validated a nanostring based assay that interrogates 4 key actionable pathways (MAPK, PI3K-AKT-mTOR, JAK-STAT, and NFkB) including RNA, protein and phosphoprotein expression. The assay was clinically validated using isogenic cell lines and a cohort of 40 gliomas with previous RNAseq. We then interrogated over 400 tumor samples, including 15 ependymomas, 11 medulloblastomas, 250 low grade gliomas (LGG), 145 high grade gliomas and 10 control normal brain specimens. Interestingly, although pediatric LGG exhibited higher MAPK activation than control tissue and other tumor types, a subset of these tumors have increased activity in PI3K , JAK and NFKB pathways. Furthermore, high PI3K activation score was correlated with worse PFS in a subset of pediatric LGGs that required adjuvant chemotherapy (p=0.018). To further explore the therapeutic implication of the assay, we analyzed a cohort of patients treated with MEK inhibitors (n=20). Strikingly, on top of universal RAS/MAPK activation, crosstalk between additional activated pathways such as PI3K and JAK-STAT may contribute to lack of response. In particular, pre-treatment and post-progression PLGG who failed therapy, revealed mild reduction in MAPK signature accompanied by increased PI3K phospho-proteins (p-S6/p-4EBP1,p-AKT)(p< 0.01). We conclude that assessing oncogenic pathway activation can add to DNA sequencing to predict different outcome and response to targeted therapies in childhood brain tumors. This can inform future therapeutic strategies including the identification of potential responders and combination strategies for non-responders.
Abstract
Diagnosis of Glioblastoma (GBM) remains a clinical challenge, currently relying on symptomatic presentation of the tumour, brain imaging and invasive biopsy. Description of effective ...biomarkers in biofluids could prove invaluable in GBM diagnosis. Extracellular vesicles (EVs) are essential to intercellular crosstalk in the tumour bulk and circulating EVs have been described as a potential reservoir of GBM biomarkers. Our work focuses on the: (i) isolation of EVs from blood liquid biopsies of GBM patients. (ii) Characterisation of their transcriptomic and proteomic cargoes to identify/validate novel candidate GBM biomarkers that could improve GBM diagnosis/prognosis. (iii) For cases where the original GBM tumour tissues are available, we will examine the expression of the identified biomarker signatures (derived from blood-EVs) to see if the content of EVs mirrors the transcriptomic/proteomic profile of the original tissue. Similar comparisons will be performed in GBM cohorts available in TCGA. Ultimately, in future studies, transcriptomic/proteomic analyses will be assessed during patients’ follow-ups to correlate the observed biomarker profiles with MRI data,treatment,recurrence, including molecular and clinical features.Our preliminary data comparing the proteomic cargoes of EVs derived from GBM patients (n=15) and those from healthy volunteers (n=10) indicated the presence of a GBM inflammatory biomarker signature comprising members of the complement and regulators of inflammation and coagulation. Bioinformatic analysis highlighted that all potential markers exclusively identified in patient samples have been linked with either GBM diagnosis,prognosis or associated signalling, suggesting that sEVs protein cargo could mirror the landscape of the original tumour and that selective circulating sEV-derived proteins might be used as hallmarks for GBM patients.Overall, this study is a step forward in the development of a non-invasive liquid biopsy approach for the identification of valuable biomarkers that could significantly improve GBM diagnosis and, consequently, patients’ prognosis and quality of life.
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