Current Technologies for RNA-Directed Liquid Diagnostics

SIMPLE SUMMARY: The discovery of nucleic acids in blood has rapidly led into the development of methods for their isolation, characterisation and validation in the context of liquid biopsy. In this emerging field, miRNAs are promising biomarkers for the detection of solid tumours in the body fluids of cancer patients. This review gives an overview of the current methods of isolating circulating free and exosomal miRNAs, the advantages and disadvantages of the methods and the different techniques for miRNA quantification. At the end, the clinical relevance and market value of RNA-based liquid biopsy are explored and discussed with respect to the field of precision medicine. ABSTRACT: There is unequivocal acceptance of the variety of enormous potential liquid nucleic acid-based diagnostics seems to offer. However, the existing controversies and the increased awareness of RNA-based techniques in society during the current global COVID-19 pandemic have made the readiness of liquid nucleic acid-based diagnostics for routine use a matter of concern. In this regard—and in the context of oncology—our review presented and discussed the status quo of RNA-based liquid diagnostics. We summarized the technical background of the available assays and benchmarked their applicability against each other. Herein, we compared the technology readiness level in the clinical context, economic aspects, implementation as part of routine point-of-care testing as well as performance power. Since the preventive care market is the most promising application sector, we also investigated whether the developments predominantly occur in the context of early disease detection or surveillance of therapy success. In addition, we provided a careful view on the current biotechnology investment activities in this sector to indicate the most attractive strategies for future economic success. Taken together, our review shall serve as a current reference, at the interplay of technology, clinical use and economic potential, to guide the interested readers in this rapid developing sector of precision medicine.