Therapy Analysis - microRNA
The main players in miRNA
It would have been hard to keep the major players in the RNA interference and antisense fields out of a field which impinges so closely on their territory. In September 2007, Alnylam, which dominates the RNA interference field in terms of IP (notably holding the Tuschl II, Kreutzer-Limmer and Crooke patents), joined forces with Isis Pharmaceuticals, the historical leader in antisense-based therapeutics, to form the US-based joint venture Regulus Therapeutics, with the aim of exploiting miRNA targets in the development of both novel siRNA- and antisense-based therapeutics. Interestingly, one of the first key projects of the collaboration has been an antisense targeting miRNA 122, the same as that for Santaris’ Phase I LNA project, for HCV and cardiovascular applications – although Regulus is also casting its net much wider into anti-inflammatory and anticancer fields. It is clear that Isis is perhaps hoping that this strategy may revive the previously flagging field of antisense therapeutics, which it pioneered with the only antisense product ever launched (fomivirsen sodium for CMV retinitis, back in 1998), but for which further true successes have remained elusive over the last decade.
Aside from these major players, start-ups keen to broadcast their specialization in miRNA have already begun to appear. It must have been quite a coup for a company to secure the highly desirable (and descriptive) name of Mirna Therapeutics – and this Texas-based concern has focused its efforts on the development of miRNA mimetics rather than inhibitors, concentrating on cancers where the targeted miRNAs are naturally down-regulated. Hot on its heels, another US start-up, Miragen, is carving a niche for itself in the contrasting area of cardiovascular drugs, developing both miRNA inhibitors and mimetics with an initial focus on heart failure; recently-published data from Miragen demonstrated that blocking the inhibitory effects of a specific miRNA called miR-208 in mice caused them not to develop the usual signs of heart failure when put under cardiac stress. It will be interesting to see whether the pipelines of these companies, and the inevitable further start-ups to follow, can compete with the larger players.
