Gene silencing promise sparks IP rush

The battle to amass intellectual property in the hot area of RNA interference (RNAi) continues to gain pace, with one of the key players in the category, Alnylam Pharmaceuticals, licensing patents from the UK's Cambridge Research Technology and Massachusetts Institute of Technology in the USA.

The company has gained exclusive rights to CRT's key RNA interference patent application 'Inhibiting gene expression with dsRNA' (WO 01/36646). The application is based on research by Magdalena Zernicka-Goetz et al​ at the University of Cambridge in the UK, that demonstrated RNAi-mediated inhibition of endogenous genes in mammalian cells.

In the agreement with MIT, Alnylam has exclusively licensed a portfolio of patent applications that address one of the major obstacles to the use of RNAi as therapeutics, namely the effective delivery of the compounds. These patent applications cover a broad range of methods for delivering nucleic acids that are applicable to RNAi and are based on the research programs of Robert Langer at MIT.

The new patents add to an IP estate that has already been fortified by the merger​ of Alnylam with Ribopharma and will be an asset in persuading companies into partnership to develop RNAi-based therapeutics, according to Alnylam.

There are a number of rivals in the rush to take RNAi into the commercial arena, however, including Sirna Therapeutics, which yesterday announced a rights offering to raise $5 million in support of its research programs in the development of RNAi-based therapeutics and diagnostics. Other key players are Qiagen and Intradigm, which recently announced an RNAi partnership, as well as Cenix Bioscience, Ribozyme Pharmaceuticals, Cytrx and Cyclacel.

Meanwhile, companies such as Ambion and Dharmacon are, at least for the moment, focusing on using RNAi as a tool for drug discovery and research.

RNAi allows the inactivation of target genes by using complementary double stranded RNA (dsRNA) that binds to messenger RNA and prevents protein transcription. It is a naturally occurring defence against molecular parasites, discovered in 1998, and offers high specificity with a level of potency and stability that is far superior to that achievable with other technologies, such as antisense or ribozymes, that have so far failed to live up to their early promise.

Despite years of research, only one antisense-based drug has ever made it through development and onto the market i.e. Isis Pharmaceuticals' Vitravene (fomivirsen) for intraocular treatment of cytomegalovirus retinitis in patients with HIV. Others have been held back by difficulties in achieving reliable systemic delivery of the compounds and stability in vivo​, as well as the high manufacturing costs of the oligonucleotide active ingredients.