EPCT-21. NEXT-GENERATION SEQUENCING OF CEREBROSPINAL FLUID FOR CLINICAL MOLECULAR DIAGNOSTICS IN ADOLESCENT AND YOUNG ADULT (AYA) BRAIN TUMOR PATIENTS

Tapping into the genome: the role of CSF ctDNA liquid biopsy in glioma

Liquid biopsy has emerged as a novel noninvasive tool in cancer diagnostics. While significant strides have been made in other malignancies using liquid biopsy for diagnosis, disease monitoring, and treatment selection, development of these assays has been more challenging for brain tumors. Recently, research in primary and metastatic brain tumors has begun to harness the potential utility of liquid biopsy-particularly using circulating tumor DNA (ctDNA). Initial studies to identify ctDNA in plasma of brain tumor patients have shown feasibility, but the yield of ctDNA is far below that for other malignancies. Attention has therefore turned to the cerebrospinal fluid (CSF) as a more robust source of ctDNA. This review discusses the unique considerations in liquid biopsy for glioma and places them in the context of the work to date. We address the utility of CSF liquid biopsy for diagnosis, longitudinal monitoring, tracking tumor evolution, clinical trial eligibility, and prognostication. We discuss the differences in assay requirements for each clinical application to best optimize factors such as efficacy, cost, and speed. Ultimately, CSF liquid biopsy has the potential to transform how we manage primary brain tumor patients.

Circulating tumor DNA profiling for childhood brain tumors: Technical challenges and evidence for utility

Cell-free DNA (cfDNA) profiling as liquid biopsy has proven value in adult-onset malignancies, serving as a patient-specific surrogate for residual disease and providing a non-invasive tool for serial interrogation of tumor genomics. However, its application in neoplasms of the central nervous system (CNS) has not been as extensively studied. Unique considerations and methodological challenges exist, which need to be addressed before cfDNA studies can be incorporated as a clinical assay for primary CNS diseases. Here, we review the current status of applying cfDNA analysis in patients with CNS tumors, with special attention to diagnosis in pediatric patients. Technical concerns, evidence for utility, and potential developments are discussed.