About RNAi
About RNA Interference & the Promise of siRNA Therapeutics
RNA interference (RNAi) is a mechanism present in living cells that inhibits the expression of a specific gene, thereby affecting the production of a protein of interest. Deemed to be one of the most important recent discoveries in life science with the potential to transform medicine, the discoverers of RNAi were awarded the Nobel Prize for Physiology or Medicine in 2006. Mediated by small interfering RNAs (siRNA), a class of ribonucleic acid (RNA) molecules, 20-25 nucleotides in length, RNAi-based therapeutics can leverage this natural pathway of gene silencing to potentially target and shut down specific disease causing genes.
Small molecule or antibody drugs have proven effective at inhibiting certain cell surface, intracellular, and extracellular targets. However, certain drug targets such as intranuclear genes and some proteins have proven difficult to inhibit with traditional drug-based and biologic therapeutics. Developing effective drugs for these targets would have the potential to address a very large underserved market for the treatment of many diseases. Using its potential to specifically target and silence virtually any gene target, siRNA therapeutics may be able to address previously "undruggable" targets, unlocking the market potential of such targets.
Several classes of RNA molecules have been utilized to generate RNAi mediated gene knockdown. Canonical siRNAs are the traditionally used 20-25 nucleotide long RNA molecules that interfere with post-transcription gene expression. Meroduplex siRNAs are three stranded RNA constructs also capable of interfering with post transcription gene expression. Dicer substrates are synthetic RNA duplexes that are approximately 27 nucleotides long, and have been shown in some studies to be more potent than 21-mer siRNA with less immune stimulation. Through licenses, Arrowhead has access to all three of these technologies collectively covering a broad range of potential targets.
RNAi as a Therapeutic Modality
- Silences the expression of disease causing genes
- Potential to address any target in the transcriptome including previously “undruggable” targets
- Rapid lead identification
- High specificity
- Opportunity to use multiple RNA sequences in one drug product for synergistic silencing of related targets
- siRNAs are uniquely suited for personalized medicine through target and cell specific delivery and knockdown