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Glioblastomas are malignant neoplasms composed of diverse cell populations. This intratumoral diversity has an underlying architecture, with a hierarchical relationship through clonal evolution from a common ancestor. Therapies are limited by emergence of resistant subclones from this phylogenetic reservoir. To characterize this clonal ancestral origin of recurrent tumors, we determined phylogenetic relationships using whole exome sequencing of pre-treatment IDH1/2 wild-type glioblastoma specimens, matched to post-treatment autopsy samples (n = 9) and metastatic extracranial post-treatment autopsy samples (n = 3). We identified “truncal” genetic events common to the evolutionary ancestry of the initial specimen and later recurrences, thereby inferring the identity of the precursor cell population. Mutations were identified in a subset of cases in known glioblastoma genes such as NF1(n = 3), TP53(n = 4) and EGFR(n = 5). However, by phylogenetic analysis, there were no protein-coding mutations as recurrent truncal events across the majority of cases. In contrast, whole copy-loss of chromosome 10 (12 of 12 cases), copy-loss of chromosome 9p21 (11 of 12 cases) and copy-gain in chromosome 7 (10 of 12 cases) were identified as shared events in the majority of cases. Strikingly, mutations in the TERT promoter were also identified as shared events in all evaluated pairs (9 of 9). Thus, we define four truncal non-coding genomic alterations that represent early genomic events in gliomagenesis, that identify the persistent cellular reservoir from which glioblastoma recurrences emerge. Therapies to target these key early genomic events are needed. These findings offer an evolutionary explanation for why precision therapies that target protein-coding mutations lack efficacy in GBM., Brain cancer: Non-coding genomic changes fuel glioblastoma growth Non-coding and structural alterations may be early drivers of brain cancer development. A team led by Priscilla Brastianos and Tracy Batchelor from Massachusetts General Hospital, Boston, USA, analyzed the genetic landscape of glioblastoma by comparing pre-treatment and autopsy tumor specimens from 12 patients who died of the aggressive brain cancer. They identified a common set of four genetic events that occurred early in the evolution of nearly every patient’s cancer: three losses or gains of chromosome regions or entire chromosomes, and mutations in the gene-activating promoter of TERT, which encodes an enzyme implicated in the cancer’s growth. The findings help explain why therapies that target protein-coding mutations don’t work in brain cancer when they do in other tumor types. They also point to new drug targets.

Although lung adenocarcinomas frequently metastasize to the brain, treatment options for lung adenocarcinoma brain metastases are limited. We discovered novel candidate drivers of progression by using case-control analyses to compare whole-exome sequencing data from a cohort of 73 lung adenocarcinoma brain metastases to a control cohort of 503 primary lung adenocarcinomas. We identified 3 genomic regions with significantly more frequent amplifications in brain metastases compared to the control cohort: MYC (12% vs 6%), YAP1 (7% vs 0.8%) and MMP13 (10% vs 0.6%). We also identified CDKN2A/B as a region deleted at a significantly greater frequency in brain metastases compared to primary lung adenocarcinomas (27% vs 13%, respectively). We confirmed frequent amplifications of MYC and YAP1/MMP13 in an independent validation cohort of 105 lung adenocarcinoma brain metastasis samples using fluorescence in situ hybridization. We further validated that MYC, YAP1 and MMP13 can drive brain metastases in a patient-derived xenograft mouse model. We found a higher incidence of metastases to the brain in mice receiving intracardiac injections of tumor cells expressing the candidate drivers compared to tumor cells expressing LacZ as a control. These results indicate that somatic alterations can drive lung adenocarcinomas to metastasize to the brain. The candidate brain metastasis drivers that we identified may serve as therapeutic targets in patients with lung adenocarcinomas who develop this devastating complication.

Glioneuronal tumors constitute a histologically diverse group of primary central nervous system neoplasms that are typically slow-growing and managed conservatively. Genetic alterations associated with glioneuronal tumors include BRAF mutations and oncogenic fusions. To further characterize this group of tumors, we collected a cohort of 26 glioneuronal tumors and performed in-depth genomic analysis. We identified mutations in BRAF (34%) and oncogenic fusions (30%), consistent with previously published reports. In addition, we discovered novel oncogenic fusions involving members of the NTRK gene family in a subset of our cohort. One-patient with BCAN exon 13 fused to NTRK1 exon 11 initially underwent a subtotal resection for a 4th ventricular glioneuronal tumor but ultimately required additional therapy due to progressive, symptomatic disease. Given the patient’s targetable fusion, the patient was enrolled on a clinical trial with entrectinib, a pan-Trk, ROS1, and ALK (anaplastic lymphoma kinase) inhibitor. The patient was treated for 11 months and during this time volumetric analysis of the lesion demonstrated a maximum reduction of 60% in the contrast-enhancing tumor compared to his pre-treatment magnetic resonance imaging study. The radiologic response was associated with resolution of his clinical symptoms and was maintained for 11 months on treatment. This report of a BCAN-NTRK1 fusion in glioneuronal tumors highlights its clinical importance as a novel, targetable alteration.