Sirna Therapeutics to Webcast Presentation at the UBS Global Specialty Pharmaceuticals Conference

SAN FRANCISCO, April 20  /PRNewswire-FirstCall/ -- Sirna Therapeutics, Inc. ("Sirna") (NASDAQ:RNAI), a leading RNAi therapeutics company, announced today that Howard W. Robin, Sirna's President and Chief Executive Officer is scheduled to give a company presentation at the UBS Global Specialty Pharmaceuticals Conference on Tuesday, April 25, 2006 at 11:30 a.m. EDT at the Grand Hyatt in New York City.

A live webcast of the presentation will be available on the Company's corporate web site at http://www.sirna.com/.  Participants are urged to log on to the web site 15 minutes prior to the scheduled start time to download and install any necessary audio software.  A replay of the webcast will be available approximately three hours after the live event and will remain accessible for four weeks, through May 25, 2006.

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 completed its Phase 1 clinical trial for Sirna-027 in AMD in 2005 and with its strategic partner, Allergan, Inc., expects to move Sirna-027 into Phase 2 clinical trials in 2006.  Sirna has selected a clinical compound for hepatitis C virus, Sirna-034, which the Company plans to bring into Phase 1 clinical trials by the end of 2006. Sirna has established an exclusive multi-year strategic alliance with GlaxoSmithKline for the development of siRNA compounds for the treatment of respiratory diseases.  Sirna has a leading intellectual property portfolio in RNAi covering over 250 mammalian gene and viral targets and over 175 issued or pending patents covering other major aspects of RNAi technology.  More information on Sirna Therapeutics is available on the Company's web site at http://www.sirna.com/.

Safe Harbor Statement

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, most drug candidates do not become approved drugs.  The development of Sirna-027 and Sirna-034 as well as Sirna's other programs are still at a relatively early stage and subject to significant risks and unknowns.  Moreover, Sirna's ability to develop products and operate as a going concern requires significant cash to fund its operating programs.  In addition, patent applications may not result in issued patents, and issued patents may not be enforceable or could be invalidated.  Other risks and uncertainties include, among others, 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 Sirna-027, Sirna-034 and Sirna's other product candidates, any of which could have negative results, Sirna's need to engage collaborators, Sirna's need to obtain and protect intellectual property, and the risk of third-party patent infringement claims.  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
  Sirna Therapeutics, Inc.
  303-449-6500

  Francesca DeMartino
  The Ruth Group
  [phone]
  

DATASOURCE: Sirna Therapeutics, Inc.



CONTACT:  Rebecca Galler Robison, Senior Director, Corporate Strategy of

Sirna Therapeutics, Inc., [phone]; or Francesca DeMartino of The Ruth

Group, [phone], , for Sirna Therapeutics,

Inc.



Web site:  http://www.sirna.com/

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