Should Dicerna Pharmaceuticals complete its planned initial public offering, the company would be the first RNAi drug developer to go public since Alnylam Pharmaceuticals did so in 2004.
Indeed, while there are a number of publicly traded RNAi therapeutics firms, all except Alnylam reached the public markets through a merger, acquisition, or some other sort of transaction with an already-public company.
For instance, RXi Pharmaceuticals was established in 2007 by CytRx as a spinout designed to continue its work with RNAi as it pursued small-molecular opportunities. RXi took a unusually roundabout path to going public in which CytRx handed off about 36 percent of the new company's shares to its existing stockholders in the form of a dividend, holding the rest itself, as it filed to sell them publicly. As a result, there was never an IPO.
Marina Biotech, meanwhile, was created when public intranasal drug delivery firm Nastech Pharmaceuticals transformed itself into an RNAi drug developer called MDRNA. That company later became Marina, holding on to the Nasdaq listing that originated with Nastech.
Similarly, one-time RNAi drug leader Sirna Therapeutics obtained its public listing from its predecessor company Ribozyme Pharmaceuticals, which changed its focus and name in 2003. Arrowhead Pharmaceuticals was also already publicly traded when it tightened its broad nanotechnology focus onto RNAi.
Likewise, Tekmira Pharmaceuticals, which trades in both Canada and the US, was created out of publicly traded Inex Pharmaceuticals in 2007, which later merged with Protiva Biotherapeutics to settle litigation related to the corporate restructuring.
And Silence Therapeutics, which trades on the London Stock Exchange, is the result of the 2005 acquisition of privately held German RNAi firm Atugen by SR Pharma, a public British biotech that turned to RNAi after its vaccine technology proved ineffective.
Lastly, Benitec Biopharma was created in 1997 out of a defunct opal-mining operation, primarily for its Australian Stock Exchange listing.
Other than Dicerna and Alnylam, there has been one other RNAi drug shop that took aim at an IPO, Quark Pharmaceuticals, which twice filed to float its shares on the Nasdaq and twice dropped its bid citing poor investor interest. The company has since been acquired by SBI Biotech, which previously was its biggest investor.