First program to apply RNA interference (RNAi) technology to asthma

Sirna Therapeutics, Inc. has announced the first program to apply RNA interference (RNAi) technology to asthma, a highly prevalent, chronic disease accounting for an estimated $13 billion in healthcare costs in the United States, a number which is forecast to grow considerably by the end of the decade.

Sirna is targeting key Th2 cytokines that play a critical role in inflammation and bronchconstriction in the airways. Results of preclinical animal studies conducted in collaboration with the National Jewish Medical and Research Center using chemically modified, systemically delivered short interfering RNAs (siRNAs) showed statistically significant reduction of airway hyperresponsiveness (66%) in the RNAi treatment group. Following additional preclinical studies, the company anticipates initiating human trials in 2006.

Extensive experimental and clinical data has demonstrated a critical role for cytokines generated by Th2 lymphocytes in the pathogenesis of asthma. Certain key cytokines orchestrate airway inflammation which underlies airway hyperresponsiveness, while others regulate the production of immunoglobulin E (IgE) in allergic asthmatics. Knocking out these cytokines by systemic or local (aerosol) delivery to the respiratory tract would be of obvious benefit in treating the disease. Sirna is currently developing siRNAs formulated to provide a long duration of activity after local administration to the lungs.

Dr. Erwin Gelfand, Chairman, Department of Pediatrics, National Jewish Medical and Research Center, commented, "Pre-clinical research in the application of Sirna's short interfering RNAs in the treatment of asthma has demonstrated proof of feasibility in animal models that siRNAs may prove to be a very novel and effective therapy for treating asthma in humans. We are extremely excited to be working with Sirna Therapeutics in this collaborative research program and look forward to submitting our data to peer review in the near future. Our hope is that asthma patients will receive significant benefits from the application of an RNAi therapy to treat this very prevalent and chronic disease."

Asthma is a chronic respiratory disease which currently affects 15 million people in the U.S. Asthma is the leading cause of childhood hospital admissions as well as absenteeism from work, and is the cause of approximately 5,000 deaths per year. Despite extensive progress in the understanding of the etiology and treatment of asthma, the prevalence of asthma has been steadily increasing for the past 20 years. Although there are many pharmaceutical treatments that manage asthma symptoms, there are no drugs that effectively modulate the progression of the disease. The U.S. market for asthma therapies in 2003 totaled $11 billion.

Howard W. Robin, President and CEO of Sirna Therapeutics, commented, "Sirna's 2004 research efforts have produced important breakthroughs in the development of RNAi technology. Sirna's asthma program is a major addition to the company's product development pipeline which includes programs in age-related macular degeneration, Huntington's Disease, dermatology, oncology, diabetes and other diseases. The prospects for success from the company's comprehensive and patent protected product pipeline are substantial. We are extremely excited about our progress and the benefits RNAi technology will bring to patients."

Sirna Therapeutics is using its proprietary technology and expertise in nucleic acids to develop a new class of nucleic acid-based therapeutics involving RNA interference. RNAi is a mechanism used by cells to regulate the expression of genes and replication of viruses. The RNA interference mechanism uses short interfering RNA (siRNA) to induce the destruction of target RNA using naturally occurring cellular protein machinery. Harnessing the natural phenomenon of RNAi holds potential for the development of a new class of drugs with specificity towards a wide range of diseases that result from undesirable protein production or viral replication.