siRNA-Based Target Identification and Validation

(Gene expression knockdown in cells in culture)

Drug Target Validation is a Bottleneck for Drug Discovery

While genomics provides many novel candidate drug targets, it is proving very difficult to decide which target(s) to pursue. This decision is critical since it is very expensive to develop a chemical entity that blocks the target and then evaluate it in animal models and humans. In light of this, it is increasingly apparent in the pharmaceutical industry that there are many more candidate drug targets for which drugs could be developed. That is, the selection of bona fide drug targets is becoming a critical, rate-limiting step in the development of new drugs. The "failed" drugs that block the target protein, but do not alleviate the disease state, account for the majority of the cost for drug development. Approaches to speed up the process for selecting valid drug targets among many potential targets would greatly reduce cost, expedite drug development and thus be of great commercial value.

The Solution: siRNA + Effective Delivery

The key to successful drug target validation in vitro is the ability to knock-down target gene expression effectively and with high specificity. By taking advantage of a revolutionary new discovery called RNA interference, it is now possible to accomplish these feats in a wide variety of cell types in culture in a much more cost effective fashion. Mirus Bio Corporation, a leader in non-viral nucleic acid transfer to cells in vitro and in vivo, has developed state-of-the-art delivery products and technologies that allow for the efficient delivery of small interfering RNAs (siRNAs) to cells for drug target validation. Mirus has focused on non-viral nucleic acid delivery since its inception and, in November of 2001, was the first company to produce and market an siRNA-specific transfection reagent. This product (TransIT-TKO® Transfection Reagent) remains the "gold standard" for attaining high efficiency delivery of siRNAs to a wide variety of cell lines. In addition, Mirus has recently developed products and kits in formats that allow for high throughput screening of target genes. Mirus is currently developing second generation siRNA delivery technologies that result in even higher levels of target gene knock-down in cells in culture.

Mirus' siRNA Delivery Solutions for In Vitro Target Validation:

• State-of-the-art siRNA delivery reagent (TransIT-TKO® Transfection Reagent).
• Novel "siRNA-generating" DNA vectors for increased knock-down efficiency and longevity.

Data:

The following represent examples of high efficiency siRNA mediated target knock-down of both reporter genes and endogenous genes using Mirus' state-of-the-art delivery products.

Selected References:

Fire, A. et al. Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. Nature 391, 806-811. (1998).

Caplen, N.J., Parrish, S., Imani, F., Fire, A. & Morgan, R.A. Specific inhibition of gene expression by small double-stranded RNAs in invertebrate and vertebrate systems. Proc Natl Acad Sci USA 98, 9742-9747. (2001).

Elbashir, S.M. et al. Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells. Nature 411, 494-498. (2001).