Introduction: Despite advances in modern medicine, brain tumor patients are still monitored purely by clinical evaluation and imaging. Traditionally, invasive strategies such as open or stereotactic biopsies have been used to confirm the etiology of clinical and imaging changes. Liquid biopsies can enable physicians to noninvasively analyze the evolution of a tumor and a patient’s response to specific treatments. However, as a consequence of biology and the current limitations in detection methods, no blood or cerebrospinal fluid (CSF) brain tumor-derived biomarkers are used in routine clinical practice. Enhancing the presence of tumor biomarkers in blood and CSF via brain-blood barrier (BBB) disruption with MRI-guided focused ultrasound (MRgFUS) is a very compelling strategy for future management of brain tumor patients. Methods: A literature review on MRgFUS-enabled brain tumor liquid biopsy was performed using Medline/Pubmed databases and clinical trial registries. Results: The therapeutic applications of MRgFUS to target brain tumors have been under intense investigation. At high-intensity, MRgFUS can ablate brain tumors and target tissues, which needs to be balanced with the increased risk for damage to surrounding normal structures. At lower-intensity and pulsed-frequency, MRgFUS may be able to disrupt the BBB transiently. Thus, while facilitating intratumoral or parenchymal access to standard or novel therapeutics, BBB disruption with MRgFUS has opened the possibility of enhanced detection of brain tumor-derived biomarkers. Conclusions: In this review, we describe the concept of MRgFUS-enabled brain tumor liquid biopsy and present the available preclinical evidence, ongoing clinical trials, limitations, and future directions of this application.

Brain metastases (BM) constitute a significant cause of oncological mortality. Statistics on the incidence of BM are limited because of the lack of systematic nationwide reporting. We report the incidence of synchronous brain metastases (sBM), defined as BM identified at the time of primary cancer diagnosis from 2015-2019 using NCI’s Surveillance, Epidemiology, and End Results (SEER) Program database. We identified 1,872,057 patients with malignancies between 2015-2019 from the SEER 17 Registries database, including 35,986 (1.9%) patients with sBM. Age-adjusted incidence rates were examined using the NCI Joinpoint software. Kaplan-Meier curves and a multivariate Cox regression model were used to investigate survival. The incidence rate of sBM from 2015 to 2019 was 7.1 persons per 100,000. Lung and bronchus cancers had the highest incidence of sBM (5.18 to 5.64 per 100,000), followed by melanoma (0.30 to 0.34 per 100,000) and breast cancers (0.24 to 0.30 per 100,000). In children, renal tumors had the highest sBM incidence. SBM were associated with poorer survival than extracranial metastases only (HR: 1.40 [95%CI: 1.39 – 1.42], P<0.001). We observed better survival in white patients relative to non-white patients with sBM (HR: 0.91 [95%CI: 0.90 - 0.94], P<0.001). The incidence rate of sBM has remained similar to rates reported over the last 9 years, with the majority associated with primary lung and bronchus cancers. SBM represent a national healthcare burden with tremendous mortality in pediatric and adult populations. This population may benefit from improved screening and treatment strategies.

Central nervous system (CNS) tumors are the leading cause of cancer death in pediatric patients. Though these tumors typically require invasive surgical procedures to diagnose, cerebrospinal fluid (CSF) liquid biopsy presents a potential method for rapid and noninvasive detection of markers of CNS malignancy. To characterize molecular biomarkers that can be used in the diagnosis, prognosis, and monitoring of pediatric cancer patients, a literature review was conducted in accordance with PRISMA guidelines. PubMed and EMBASE were searched for the terms biomarkers, liquid biopsy, cerebrospinal fluid, pediatric central nervous system tumor, and their synonyms. Studies including pediatric patients with CSF sampling for tumor evaluation were included. Studies were excluded if they did not have full text or if they were case studies, methodology reports, in languages other than English, or animal studies. Our search revealed 163 articles of which 42 were included. Proteomic, genomic, and small molecule markers associated with CNS tumors were identified for further analysis and development of detection tools.

Diagnosis and longitudinal monitoring of neurological diseases are limited by the poor specificity and limited resolution of currently available techniques. Analysis of circulating cells in cerebrospinal fluid (CSF) has emerged as a promising strategy for the diagnosis, molecular characterization, and monitoring of neurological disease. In comparison to bulk sequencing analysis, single-cell sequencing studies can provide novel insights into rare cell populations and uncover heterogeneity in gene expression at a single-cell resolution, which has several implications for understanding disease pathology and treatment. Parallel development of standardized biofluid collection protocols, pre-processing strategies, reliable single-cell isolation strategies, downstream genomic analysis, and robust computational analysis is paramount for comprehensive single-cell sequencing analysis. Here we perform a comprehensive review of studies focusing on single-cell sequencing of cells in the CSF of patients with oncological or non-oncological diseases of the central nervous system.

Glioblastoma (GBM) is the most common primary brain tumor in adults, with a median survival of 15–18 months. GBM cells, like all tumors, exhibit a metabolic shift known as the Warburg effect, favoring glycolysis even under normoxic conditions. GLUT1 is a primary glucose transporter in GBM cells and has been found to be overexpressed in these cells. The acidic microenvironment created by glycolysis facilitates immune evasion, therapy resistance, and tumor growth. Overexpression of GLUT1 is driven by hypoxia-inducible factor-1α (HIF-1α), c-Myc, and other pathways which have been correlated with tumor aggressiveness as well as poor prognosis Recent studies have highlighted the therapeutic potential of targeting GLUT1 in GBM. Preclinical research shows that GLUT1 inhibitors, such as WZB117 and BAY-876, effectively impair tumor metabolism, reduce cell viability, and improve survival in vitro and in animal models. GLUT1 expression also serves as a prognostic marker, with elevated levels linked to poor outcomes. This review highlights the importance of GLUT1 in GBM biology as a potential therapeutic target and biomarker.