Extracellular Vesicles as Predictive Biomarkers for Chemotherapy-Induced Peripheral Neuropathy

CIPN is a frequent and often long-lasting complication of treatment with several commonly used antineoplastic agents, including taxanes, platinum compounds, and antimitotic drugs. The condition primarily affects sensory neurons of the dorsal root ganglia and peripheral nerve fibers, leading to symptoms such as numbness, tingling, pain, and loss of vibration or tactile sensation. The severity and persistence of CIPN vary markedly between individuals, and currently there are no validated biological markers that allow early identification of patients at increased risk or objective monitoring of neurotoxicity during treatment. As a result, CIPN is usually detected only after clinical symptoms appear, at a stage when nerve damage may already be established and difficult to reverse.

EVs are membrane-bound particles released by virtually all cell types and present in large numbers in biological fluids, including blood. They contain proteins, lipids, and nucleic acids that reflect the physiological and pathological state of their cells of origin. Because EVs can originate from neural and glial cells and can cross biological barriers, they provide a potential window into otherwise inaccessible tissues such as the peripheral nervous system. Changes in EV concentration, membrane composition, and RNA cargo have been reported in several neurological and neurodegenerative conditions, supporting their potential role as circulating indicators of neuronal injury and dysfunction.

This study is designed to evaluate whether longitudinal changes in circulating EVs are associated with the development of CIPN in patients undergoing chemotherapy. Blood samples collected at predefined time points will be used to isolate and quantify EVs and to characterize selected molecular components of their cargo, including membrane lipids and microRNAs. These EV-based measurements will be evaluated in relation to standardized clinical and neurophysiological assessments of peripheral neuropathy performed over the course of treatment and follow-up. By integrating biological and clinical data, the study aims to explore whether EV-derived markers reflect early neurotoxic effects of chemotherapy and whether they may capture individual susceptibility to CIPN.

The study uses a single-group, longitudinal design in which each participant serves as their own reference over time. This approach allows the evaluation of intra-individual changes in EV-related parameters across the different phases of chemotherapy exposure and recovery. It is particularly suited for biomarker discovery in conditions such as CIPN, where baseline inter-individual variability is high and where the key biological signal of interest is the change from an individual's pre-treatment state. This design also avoids the need for a concurrent untreated control group, which would not be ethically or clinically appropriate in this setting.

EVs will be isolated from plasma using standardized protocols designed to preserve vesicle integrity and minimize contamination from non-vesicular particles. Quantitative analysis will be performed to determine the concentration of circulating EVs, expressed as vesicles per microliter, at each study time point. In addition, qualitative analyses will be carried out to investigate specific components of EV cargo that may be relevant to nerve injury and inflammation. These include selected classes of membrane lipids, such as phosphatidylcholine, sphingomyelin, and cholesterol, which are known to influence membrane stability and signaling, as well as microRNAs involved in neuronal function, stress responses, and neuroinflammatory pathways. The combination of quantitative and molecular profiling is intended to provide a multidimensional view of EV dynamics in relation to chemotherapy exposure.