Low-Pass Whole Genome Sequencing of Cell-Free DNA from Cerebrospinal Fluid: A Focus on Pediatric Central Nervous System Tumors

Abstract Background Cell-free DNA (cfDNA) technology has allowed for cerebrospinal fluid (CSF), a previously underutilized biofluid, to be analyzed in new ways. The interrogation of CSF-derived cfDNA is giving rise to novel molecular insights, particularly in pediatric central nervous system (CNS) tumors, where invasive tumor tissue acquisition may be challenging. Contemporary disease monitoring is currently restricted to radiographic surveillance by magnetic resonance imaging and CSF cytology to directly detect abnormal cells and cell clusters. Alternatively, cfDNA is often present in the CSF from pediatric patients with both malignant and nonmalignant CNS tumors and can be accessed by minimally invasive lumbar puncture and other CSF-liberating procedures, offering a promising alternative for longitudinal molecular disease analysis and surveillance. Content This review explores the use of low-pass whole genome sequencing (LP-WGS) to analyze cfDNA from the CSF of pediatric patients with CNS tumors. This platform is uniquely poised for the detection of tumors harboring copy number variants, which are prevalent in this population. The utility and sensitivity of LP-WGS as a clinical tool is explored and discussed in the context of alternative CSF liquid biopsy interrogation modalities, including nanopore sequencing and methylation array. Summary Analysis of CSF-derived cfDNA by LP-WGS has broad diagnostic, prognostic, and clinical implications for pediatric patients with CNS tumors. Careful interpretation of LP-WGS results may aid in therapeutic targeting of pediatric CNS tumors and may provide insight into tumor heterogeneity and evolution over time, without the need for invasive and potentially risky tissue sampling.