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BOTHELL, WA, May 06, 2010 (MARKETWIRE via COMTEX) -- MDRNA, Inc. (NASDAQ:
MRNA), a leading RNAi-based drug discovery and development company, today
reported on advances made with the Company's proprietary UsiRNA construct for
RNA interference (RNAi). The term UsiRNA denotes inclusion of unlocked
nucleobase analogs (UNA) in the double-stranded oligonucleotide construct.
UsiRNAs demonstrate enhanced specificity and efficacy in comparison to standard
siRNAs. Today's data add to previously reported data on microarray analysis
indicating the UsiRNA construct not only significantly eliminates off-target
events, but does so with no apparent new off-target silencing. That is, UNA's
improve the efficacy of the siRNA construct without further off-target activity
related to the UNA chemistry. The data were presented by Narendra Vaish, Ph.D.,
MBA, Associate Director, Discovery Research and Pharmaceutical Development, at
the "RNAi and miRNA World Congress" in Boston, MA.

RNAi provides a means to target a specific mRNA and this "on-target" precision
is a key advantage for RNAi-based therapeutics. However, the potential exists
for "off-target" effects with standard siRNAs via the non-targeting strand
(e.g., passenger strand) or unintended interactions associated with the
targeting strand (e.g. guide strand). The UsiRNA construct was designed to
directly address these concerns. Substitution in the passenger strand is
intended to eliminate its participation in the RNAi process. Substitution in the
guide strand is intended to eliminate miRNA-like events, while preserving
siRNA-like activity. Furthermore, as described previously, UsiRNAs have a lower
potential for cytokine induction that can occur with standard siRNAs, and the
absence of alterations in cytokine related genes are likely a part of the
overall reduction in the off-target events.

Activity evaluation and microarray analysis confirmed the advantages of UsiRNAs.
Compared to the standard siRNA format, elimination of passenger strand activity
was achieved with UNA substitution. Guide strand substitution with UNA retained
intended siRNA-like activity but demonstrated no miRNA-like activity. Microarray
analysis revealed significant change in the expression of 389 genes with the
standard siRNA format. In contrast, UsiRNA altered expression of only 35 genes,
a greater than 90% reduction in off-target events with no apparent new
off-target silencing.

"These new data highlight the ability of our UsiRNA construct to achieve highly
specific inhibition while mitigating the off-target effects that can occur with
standard siRNAs," said Dr. Barry Polisky, Chief Scientific Officer of MDRNA.
"The inhibition of target mRNA in our bladder cancer model, demonstrates the
strength of pairing the UsiRNA construct and DiLA2 delivery platforms for the
development of RNAi-based therapeutics."

About MDRNA's Technology

MDRNA has a broad intellectual property estate that encompasses four key RNAi
technology platforms: siRNA constructs, chemistry, nucleic acid delivery, and
gene targets. The MDRNA-owned siRNA constructs and chemistry include its
proprietary UsiRNA construct, which is a duplex siRNA in which non-nucleotide
acyclic monomers (UNAs) have been included, and is distinct from the standard
siRNA construct used by others in the industry. UsiRNAs are fully recognized by
the RNAi machinery and provide for potent RNAi activity while specific placement
of UNAs in a duplex siRNA minimizes potential off-target effects by the guide
strand and reduces undesired passenger strand activity. Furthermore, UsiRNAs
escape the surveillance mechanisms associated with cytokine induction, and
provide protection from nuclease degradation.

The MDRNA delivery platforms include DiLA2 and nanoparticle forming peptides.
DiLA2 is an MDRNA proprietary delivery platform of novel synthetic di-alkylated
amino acid compounds used to make liposomal delivery formulations. The DiLA2
platform enables MDRNA to tailor the charge, linker and acyl chains of amino
acids in order to configure liposomes for delivery to target tissues of
interest. In addition, the platform is designed to permit attachment of various
peptides and other targeting molecules to improve a variety of delivery
characteristics. The MDRNA peptide nanoparticle platform includes exclusively
in-licensed and developed IP surrounding the use of peptides for nanoparticle
formulations that increase cellular uptake and endosomal release of siRNAs.
MDRNA is currently biopanning its patented phage display library to identify
additional peptides for targeted delivery, cellular uptake and endosomal release
of siRNA.

MDRNA owns or controls 17 issued or allowed patents, and has 41 pending patent
applications, 134 pending foreign patent applications and 6 PCT applications.

About MDRNA, Inc.

MDRNA is a biotechnology company focused on the development and
commercialization of therapeutic products based on RNA interference (RNAi). Our
goal is to improve human health through the development of RNAi-based compounds
and drug delivery technologies that together provide superior therapeutic
options for patients. Over the past decade, we have developed substantial
capabilities in molecular biology, cellular biology, lipid chemistry, peptide
chemistry, pharmacology and bioinformatics, which we are applying to a wide
range of RNAi technologies and delivery approaches. These capabilities plus the
in-licensing of key RNAi-related intellectual property have rapidly enabled us
to become a leading RNAi-based therapeutics company with a pre-clinical pipeline
in oncology. Through our capabilities, expertise and know-how, we are
incorporating multiple RNAi technologies as well as peptide- and lipid-based
delivery approaches into a single integrated drug discovery platform that will
be the engine for our clinical pipeline as well as a versatile platform for
establishing broad therapeutic partnerships with biotechnology and
pharmaceutical companies. We are also investing in new technologies that we
expect to lead to safer and more effective RNAi-based therapeutics while
aggressively building upon our broad and extensive intellectual property estate.
By combining broad expertise in siRNA science with proven delivery platforms and
a strong IP position, MDRNA is well positioned as a leading RNAi-based drug
discovery and development company. Additional information about MDRNA, Inc. is
available at http://www.mdrnainc.com.