MDRNA, Inc. Reports Positive In Vivo Data Demonstrating That Its UsiRNAs Are Highly Potent Against Metabolic and Oncology Targets

BOTHELL, WA--(Marketwire - August 3, 2009) - MDRNA, Inc. (NASDAQ: MRNA) announced today positive data on its proprietary UsiRNA technology, demonstrating that its UsiRNAs are highly potent against metabolic disease and cancer targets in rodent models. Further, the data establish that the knockdown of these targets is achieved via an RNAi-mediated process. Of particular importance is that the data demonstrate that strategic placement of UNA (unlocked nucleobase analogs) results in the ability to manipulate, either increasing or decreasing, strand-specific activity thus minimizing off-target activity and providing the ability to impart improved drug-like characteristics to the UsiRNAs. The data are being presented today by Michael V. Templin, Ph.D., Vice President, Discovery Research and Pharmaceutical Development of MDRNA, at the IBC Drug Discovery & Development Week, Oligonucleotide Therapeutics: From Concept to Implementation, in Boston, Massachusetts.

"UNA-modified siRNAs are novel and proprietary constructs that have high potency in target mRNA reduction. In addition, we have recently determined that strategic placement of UNA in the siRNA reduces micro-RNA-like off-target activity. This observation is distinct from, and in addition to, our previous work in which we have demonstrated that UNA residues have a dramatic effect on reduction of cytokine induction by siRNA," stated Barry Polisky, Ph.D., Chief Scientific Officer of MDRNA. "We are encouraged by these significant results that demonstrate the versatility of UNA and UsiRNAs for improving the safety and specificity of RNAi, and reinforce our confidence in our UsiRNA platform."

"Repeated positive results from multiple in vivo studies in rodents using our UsiRNAs and DiLA2 delivery platform has led us to the initiation of preclinical safety and efficacy studies in non-human primates," stated J. Michael French, President and Chief Executive Officer. "We are one of a handful of companies to have initiated non-human primate studies with a liposomal-based delivery system and we look forward to reporting positive data this quarter."

About Unlocked Nucleobase Analogs and UsiRNAs

Unlocked Nucleobase Analogs (UNA) are substitutes for nucleotides that make up conventional siRNAs. UNAs have an open structure in the place of the ribose portion, making them more flexible than common nucleotides. UsiRNAs are a duplex siRNAs containing at least one UNA. UsiRNAs are fully recognized by the cellular RNAi machinery, as demonstrated by their potent activity. MDRNA has also shown that inclusion of UNA increases stability to nucleases, substantially reduces cytokine induction, and reduces passenger and guide strand-mediated off-target effects. The high potency, and improved drug-like properties, associated with UsiRNAs provide the potential to greatly enhance RNAi-based therapeutics.

About the DiLA2 Delivery Platform

The DiLA2 Delivery Platform is MDRNA's proprietary platform for creating novel liposomal delivery systems based on di-alkylated amino acids (DiLA2). The DiLA2 Platform enables MDRNA to tailor the charge, linker length, and acyl chain characteristics to improve delivery of the liposomes to target tissue of interest. In vivo studies have demonstrated effective delivery in models of metabolic disease, cancer, and other targets. DiLA2-based liposomes are well tolerated for repeat dose, and systemic and local administration. MDRNA is also utilizing condensing peptides to form peptide-siRNA nanoparticles to further increase the delivery efficiency of its DiLA2 delivery systems. In addition, the platform is designed to permit attachment of peptides and other targeting molecules for delivery to a variety of tissues, and thus provide for a diverse therapeutic portfolio.

MDRNA Forward-Looking Statements

Statements made in this news release may be forward-looking statements within the meaning of Federal Securities laws that are subject to certain risks and uncertainties and involve factors that may cause actual results to differ materially from those projected or suggested. Factors that could cause actual results to differ materially from those in forward-looking statements include, but are not limited to: (i) the ability of MDRNA to obtain additional funding; (ii) the ability of MDRNA to attract and/or maintain manufacturing, research, development and commercialization partners; (iii) the ability of MDRNA and/or a partner to successfully complete product research and development, including preclinical and clinical studies and commercialization; (iv) the ability of MDRNA and/or a partner to obtain required governmental approvals; and (v) the ability of MDRNA and/or a partner to develop and commercialize products that can compete favorably with those of competitors. Additional factors that could cause actual results to differ materially from those projected or suggested in any forward-looking statements are contained in MDRNA's most recent periodic reports on Form 10-K and Form 10-Q that are filed with the Securities and Exchange Commission. MDRNA assumes no obligation to update and supplement forward-looking statements because of subsequent events.

Contact Information: Contact: Matthew D. Haines Senior Director, Investor Relations and Corporate Communications (212) 209-3874 McKinney|Chicago (Media) Alan Zachary (312) 944-6784 x 316 (708) 707-6834