Exosomes as therapeutics and drug delivery vehicles: global regulatory perspectives
Cell & Gene Therapy Insights 2020; 6(11), 1561–1569
Exosomes are nano-sized extracellular vesicles secreted by all cells. Extensive research over recent years has now shown these vesicles to be important players in intercellular signalling and to have a role in tissue regeneration, immunomodulation and other biological functions. A lipid bilayer protects the exosome cargo of nucleic acids and proteins from degradation and permits signalling over long distances. The signalling characteristics of the cargo have led to exosomes being evaluated as therapeutics in their own right, while the protective lipid envelope and tissue tropism of exosomes suggests potential use as delivery vehicles for drugs that are usually rapidly degraded in the body. This range of potential uses raises interesting regulatory questions and challenges. Although derived from cells and containing nucleic acids, exosomes will not be considered as Advanced Therapy Medicinal Products (ATMPs) in Europe, unless they are used to deliver gene therapy. As biological medicinal products, whether exosomes would fall under the mandatory scope of the Centralised Procedure in Europe or fall under the jurisdiction of the Center for Biologics Evaluation and Research (CBER) or the Center for Drug Evaluation and Research (CDER) in the USA would depend on what they are being used to deliver. The legal classification and jurisdiction will go on to impact regulatory strategy and development plans. Characterisation of the exosome, reproducibility of production, potency assays, viral safety, toxicology study design and starting dose in man will be critical considerations as for other biological products.