2 September 2015 - - US-based RNA interference therapeutics developer Dicerna Pharmaceuticals, Inc. (NASDAQ: DRNA) has submitted an investigational new drug application to the US Food and Drug Administration for DCR-PH1, the company's therapeutic candidate for the treatment of primary hyperoxaluria type 1, Dicerna said on Wednesday. PH1 is a severe, rare, inherited disorder of the liver that often results in kidney failure and for which there are no approved therapies. DCR-PH1 incorporates small interfering RNA (siRNA) formulated in a proprietary lipid nanoparticle technology that is being investigated as a system for efficient delivery to the liver after intravenous administration. Dicerna obtained rights to this delivery technology by way of a licensing agreement with Arbutus Biopharma Corp., formerly Tekmira Pharmaceuticals Corp. Currently, there are no approved therapies for the treatment of PH1 in the US and the EU. Patients with this disease often undergo combined liver and kidney transplant, a major surgical procedure, and subsequently must take immunosuppressant drugs for the rest of their lives, and there is a potential for a future re-transplant and possible cancers. Dicerna's proprietary RNAi molecules are known as Dicer substrate short-interfering RNA molecules, or DsiRNAs, so called because they are processed by the Dicer enzyme, which is the initiation point for RNAi in the human cell cytoplasm. The company's discovery approach seeks to maximize RNAi potency through development of DsiRNAs that are thought to be ideally structured for processing by Dicer. Dicer processing enables the preferential use of the correct RNA strand of the DsiRNA, which may increase the efficacy of the RNAi mechanism, as well as the potency of the DsiRNA molecules relative to other molecules used to induce RNAi.