How Laboratory Guidelines Promote the Validity of Circulating Extracellular Vesicle-Associated Nucleic Acid Biomarker Signatures in Liquid Biopsy

Circulating nucleic acids, particularly those associated with extracellular vesicles (EVs), represent a promising class of molecular biomarkers in liquid biopsy for ‘non-invasive’ disease diagnostics, for better prognosis, and for therapeutic monitoring. However, the translation of this new circulating biomarker source into clinical practice is mostly hindered by methodological variability and a lack of standardization across the analytical workflow. This article highlights the implementation of international academic guidelines, such as Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) and Minimal Information for Studies of Extracellular Vesicles (MISEV), in the entire analytical procedure in promoting the integrity, reproducibility, and validity of EV-associated nucleic acid markers in molecular diagnostics. By standardizing the liquid biopsy workflow from tissue sampling up to data analysis and statistics, these established guidelines lay the necessary scientific basis for a robust, reproducible, reliable, and valid RNA and DNA biomarker discovery in EVs. The ultimate goal is the successful implementation of the developed biomarker signature into the clinical diagnostic routine, but this requires further rounds of rigorous validation. The regularly updated guidelines should not be seen as optional recommendations, but more like an essential pillars of scientific rigor and standardization in order to achieve better and biological meaningful biomarker results in liquid biopsy.