RNAi-based drug design: considerations and future directions

Abstract

More than 25 years after its discovery, the post-transcriptional gene regulation mechanism termed RNAi is now transforming pharmaceutical development, proved by the recent FDA approval of multiple small interfering RNA (siRNA) drugs that target the liver. Synthetic siRNAs that trigger RNAi have the potential to specifically silence virtually any therapeutic target with unprecedented potency and durability. Bringing this innovative class of medicines to patients, however, has been riddled with substantial challenges, with delivery issues at the forefront. Several classes of siRNA drug are under clinical evaluation, but their utility in treating extrahepatic diseases remains limited, demanding continued innovation. In this Review, we discuss principal considerations and future directions in the design of therapeutic siRNAs, with a particular emphasis on chemistry, the application of informatics, delivery strategies and the importance of careful target selection, which together influence therapeutic success. Since the groundbreaking discovery of RNAi more than 25 years ago, several small interfering RNA (siRNA)-based therapies that target the liver have gained approval. This Review discusses principal considerations in siRNA-based drug development, focusing on the medicinal chemistry of siRNA design, the application of informatics, delivery platforms and future directions.