Extracellular Vesicles in the Biology and Liquid Biopsy Diagnostics of Pediatric High‐Grade Glioma – Emerging Findings and Opportunities

ABSTRACT Liquid biopsy has emerged as an important diagnostic paradigm impacting care across multiple cancer indications. This is also an area of great interest in pediatric solid tumours, including those affecting the central nervous system (CNS). Of special concern are pediatric high‐grade gliomas (pHGGs) due to the associated diagnostic complexities, poor outcomes and difficult access to tumour tissue, especially for midline lesions. In this commentary we discuss the applicability of different liquid biopsy analytes accessible in cerebrospinal fluid or blood to detect, monitor or molecularly diagnose pHGG, concentrating on the emerging biology of extracellular vesicles and particles (EVPs), as both biological mediators and sources of diagnostic information. We highlight the role of oncogenic pathways in shaping the profiles of EVPs in brain tumours, and we point to diagnostic opportunities associated with the discovery of oncohistones, as possible modulators of EVP landscapes in pHGG.