Next-Gen Extracellular Vesicles: Biomarkers, Targets, Deliverables in Oncology

Extracellular vesicles (EVs) are lipid bilayer-bound particles released by cells, carrying a diverse cargo of proteins, lipids, and nucleic acids (DNA, RNA, miRNA).¹ These vesicles, including exosomes (30-150 nm), microvesicles (100-1000 nm), and apoptotic bodies (500-5000 nm), mediate intercellular communication by transferring their contents to recipient cells, thereby influencing physiological and pathological processes.² In oncology, tumour-derived EVs (TEVs) play a role in tumour progression, metastasis, angiogenesis, immune evasion, and drug resistance.³ Their presence in biological fluids, such as blood, urine, and cerebrospinal fluid, makes them accessible for non-invasive analysis, positioning them as promising biomarkers for cancer detection, prognosis, and monitoring treatment response.⁴

EVs and EPs in Cancer Management

The cargo within EVs and EPs reflects the molecular status of their parent cells, offering a snapshot of the tumour microenvironment. For instance, specific EV-associated proteins, such as epidermal growth factor receptor (EGFR) in non-small cell lung cancer or human epidermal growth factor receptor 2 (HER2) in breast cancer, can serve as diagnostic or prognostic markers.^5,6 Similarly, EV-encapsulated microRNAs (miRNAs) have demonstrated potential as biomarkers; for example, elevated levels of miR-21 in circulating EVs have been correlated with various cancers, including colorectal and pancreatic cancer, indicating disease presence or progression.^7,8 The stability of these molecules within the EV lipid bilayer protects them from degradation by circulating nucleases and proteases, enhancing their utility in liquid biopsy applications.⁹

Beyond their biomarker potential, EVs are being explored as therapeutic targets. Inhibiting EV biogenesis or uptake by tumour cells could disrupt critical communication pathways that support tumour growth and metastasis. For example, agents that block neutral sphingomyelinase 2 (nSMase2), an enzyme involved in exosome formation, have shown preclinical efficacy in reducing tumour growth and metastasis.¹⁰ Furthermore, the inherent ability of EVs to deliver biological cargo to specific cells makes them attractive candidates for drug delivery systems. EVs can be engineered to carry therapeutic agents, such as small molecule drugs, siRNAs, or CRISPR/Cas9 components, directly to tumour cells, potentially reducing off-target effects and improving therapeutic indices.¹¹ Preclinical studies have demonstrated the successful delivery of chemotherapeutic agents, such as doxorubicin, via engineered exosomes, leading to enhanced anti-tumour effects in various cancer models.¹²

The development of advanced isolation and characterisation techniques is critical for translating EV research into clinical practice. Methods such as ultracentrifugation, size-exclusion chromatography, immunoaffinity capture, and microfluidics are continually being refined to improve the purity and yield of EV preparations.¹³ These technological advancements are essential for standardising EV analysis and ensuring the reproducibility required for clinical validation. The complexity of EV populations, including heterogeneity in size, origin, and cargo, presents challenges for comprehensive characterisation and necessitates robust analytical platforms.¹⁴

Limitations and Future Directions

Despite the promise, several limitations must be addressed before EVs and EPs can be widely adopted in clinical oncology. Standardisation of isolation and characterisation protocols remains a significant hurdle, impacting the comparability of results across studies. The precise mechanisms of EV uptake and cargo release by recipient cells are not fully elucidated, which is crucial for optimising EV-based drug delivery. Furthermore, the scalability of therapeutic EV production and the potential for immunogenicity need careful consideration for clinical translation. Future research will focus on developing highly specific and sensitive EV-based assays, refining engineering strategies for targeted drug delivery, and conducting large-scale clinical trials to validate their utility in diverse cancer types. The integration of EV analysis with other omics technologies (genomics, proteomics, metabolomics) may provide a more comprehensive understanding of cancer biology and facilitate the development of personalised treatment strategies.¹⁵