Sirna Therapeutics Publishes Hepatitis B Virus Data in June 2005 Issue of Hepatology
Demonstrates Importance of Chemical Modifications to siRNAs for Therapeutically Relevant Molecules
BOULDER, Colo., and SAN FRANCISCO, June 7 /PRNewswire-FirstCall/ -- Sirna Therapeutics, Inc. (Nasdaq: RNAI), a leading RNAi therapeutics company, announced today the publication of an article in Hepatology addressing the activity of chemically modified short interfering RNA (siRNA) in a mouse model of hepatitis B virus replication. In the article, Sirna demonstrated in vivo validation of chemical modifications of siRNAs and the distinct differences between modified and unmodified molecules necessary for therapeutic relevance.
As noted in a Hepatology editorial in the same issue, "[the Sirna scientists] take a step beyond "proof of concept" studies to investigate chemical modifications to small interfering RNAs (siRNAs) that prove their efficacy in a mouse model of hepatitis B virus replication. They demonstrate that chemically modified siRNAs have improved delivery characteristics, both in terms of stability and efficacy in vivo. Importantly, siRNAs delivered via a clinically relevant route -- standard intravenous injection -- reduced hepatitis B virus (HBV) replication in mice."
To initially assess activity of the stabilized siRNAs in vivo, an HBV vector-based model was employed in which the siRNA and the HBV vector were co-delivered via high volume tail vein injection. More than a 3 log10 decrease in levels of serum HBV DNA and HBsAg, as well as liver HBV RNA, were observed in the siRNA treated groups compared to the control siRNA treated and saline groups. Furthermore, the observed decrease in serum HBV DNA was 1.5 log10 greater with a modified siRNA compared to an unmodified siRNA indicating the value of chemical modification in therapeutic applications of siRNA. Progressing beyond high volume tail vein injection in subsequent experiments, standard systemic intravenous dosing of modified siRNA, resulted in an approximately 1 log10 reduction of serum HBV DNA levels while no activity was observed with unmodified siRNA. These experiments establish the strong impact that siRNAs can have on the extent of HBV infection and underscore the importance of modification of siRNA against nuclease degradation. The siRNAs used in these experiments were fully chemically modified in that no standard ribose sugars were present in the structure. The data presented constitute an important proof that Sirna's invention of these "no ribose" forms have significant therapeutic potential.
"We are pleased with the publication of these data in Hepatology and see it as further validation of Sirna's progress translating RNAi science into clinically relevant therapeutics," said Howard W. Robin, Sirna President and CEO. "Sirna continues its groundbreaking work in siRNAs developing novel chemical modifications and delivery technologies. Following our research cited in this publication, we have made significant progress in successfully delivering modified siRNAs resulting in dramatic reduction of HBV titers at clinically relevant doses."
About RNA interference
RNA interference (RNAi) is a natural, selective process for turning off genes. RNAi is triggered by short interfering RNA (siRNA) molecules that engage a group of cellular proteins, known as RISC (RNA induced silencing complex). The RISC guides the siRNA to its target messenger RNA (mRNA, the messenger between DNA and proteins) by complementary base pairing for the targeted break-up of the mRNA thus halting protein expression or viral replication. The RISC-siRNA-complex binds and cleaves multiple mRNA molecules in a catalytic fashion.
About Sirna Therapeutics
Sirna Therapeutics is a clinical-stage biotechnology company developing RNAi-based therapies for serious diseases and conditions, including age-related macular degeneration (AMD), hepatitis B and C, dermatology, asthma, Huntington's Disease, diabetes and oncology. Sirna Therapeutics has initiated a Phase 1 clinical trial for its most advanced compound, Sirna-027, a chemically modified siRNA targeting the clinically validated vascular endothelial growth factor pathway to treat AMD. Sirna Therapeutics has strategic partnerships with Eli Lilly and Company, Targeted Genetics and Archemix Corporation and a leading intellectual property portfolio in RNAi. More information on Sirna Therapeutics is available on the Company's web site at http://www.sirna.com/.
Statements in this press release which are not strictly historical are "forward-looking" statements which should be considered as subject to many risks and uncertainties. For example, promising animal data often does not lead to promising human results and most drug candidates fail to become products. Additional risks and uncertainties include Sirna's early stage of development and short operating history, Sirna's history and expectation of losses and need to raise capital, Sirna's need to obtain clinical validation and regulatory approval for products, Sirna's need to obtain and protect intellectual property, risk of third-party patent infringement claims, Sirna's need to attract and retain qualified personnel, Sirna's need to engage collaborators, availability of materials for product manufacturing, the highly competitive nature of the pharmaceutical market, the limited trading volume and history of volatility of Sirna's common stock, Sirna's concentration of stock ownership, and risks from relocating Sirna headquarters. These and additional risk factors are identified in Sirna's Securities and Exchange Commission filings, including the Forms 10-K and 10-Q and in other SEC filings. Sirna undertakes no obligation to revise or update any forward-looking statements in order to reflect events or circumstances that may arise after the date of this release.
Contacts:
Rebecca Galler Robison, Senior Director, Corporate Strategy of Sirna
Therapeutics, Inc.,
+1-303-449-6500
or Zack Kubow of The Ruth Group,
+1-646-536-7020
SOURCE Sirna Therapeutics, Inc.
06/07/2005
CONTACT: Rebecca Galler Robison, Senior Director, Corporate Strategy of Sirna Therapeutics, Inc., +1-303-449-6500;
or Zack Kubow of The Ruth Group, +1-646-536-7020, for Sirna Therapeutics, Inc.
Web site: http://www.sirna.com
(RNAI)
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发表于 2005-9-2 05:05
