Company to Host Webcast to Review Results of Crohn's Disease and Ulcerative Colitis Trials Today at 7:30 AM ET

CARLSBAD, Calif., Dec. 2 /PRNewswire-FirstCall/ -- Isis Pharmaceuticals, Inc. (Nasdaq: ISIS) announced today results of two Phase 3 trials that evaluated the first-generation antisense drug alicaforsen in patients with Crohn's disease. In two identically designed Phase 3 trials, alicaforsen did not demonstrate statistically significant induction of clinical remissions compared to placebo. Clinical remission evidenced by an improvement in Crohn's Disease Activity Index (CDAI) scores by week 12 was the primary endpoint of both trials. In both Phase 3 clinical studies, alicaforsen was well-tolerated. As a result of these data, the company has determined it will not invest further in the development of alicaforsen for Crohn's disease.

Alicaforsen was also studied in an enema formulation in patients with ulcerative colitis. In a separate press release issued today, results of three Phase 2 clinical trials of alicaforsen enema showed that the drug significantly improved symptoms and produced durable responses in patients with ulcerative colitis.

"We had hoped for a much better outcome in these Phase 3 trials in Crohn's disease, yet we are very pleased with the drug's performance in patients with ulcerative colitis. These trials add a significant amount of data to our growing safety experience with antisense drugs and are invaluable to our better understanding of these compounds," said Stanley T. Crooke, M.D., Ph.D., Chairman and CEO of Isis. "We believe alicaforsen enema represents an attractive commercial product opportunity for Isis. Following alicaforsen enema we have a robust portfolio of second-generation drugs with the opportunity to address large markets. Data on these promising newer drugs is strong, and our focus is now on moving them aggressively towards commercialization."

About the Phase 3 Clinical Trials of Alicaforsen for Crohn's Disease

Isis conducted two randomized, double-blind, placebo-controlled Phase 3 studies of alicaforsen in patients with active moderate-to-severe Crohn's disease. The first trial, which was conducted in North America, enrolled 151 patients and the second trial, which was conducted in Europe and in Israel, enrolled 180 patients.

In the studies, patients received either placebo or 300mg of alicaforsen by intravenous infusion three times a week for four weeks. Patients were followed for response for six months, and alicaforsen-treated patients who achieved clinical remissions were followed for up to one year.

The primary endpoint for both trials was clinical remission (defined as a CDAI score of 150 or less) by week 12. CDAI is a common clinical scoring system for the severity of symptoms related to Crohn's disease.

Isis will conduct a live webcast conference call to review these results today, at 7:30 AM Eastern time. To participate over the Internet go to www.isispharm.com. A replay of the webcast will be available at this address.

About Alicaforsen

Alicaforsen is an inhibitor of ICAM-1, a molecule that plays a key role in a wide range of inflammatory and autoimmune conditions. ICAM-1 influences lymphocyte function, pivotal in cell trafficking. ICAM-1 is part of a molecular family (known as Cellular Adhesion Molecules, or CAMs) that can be found on the surface of virtually every cell in the body, including cells that line the inflamed gastrointestinal (GI) tract.

About Crohn's Disease

Crohn's disease is an inflammatory bowel disease. Approximately one million people in the U.S. and in Europe are diagnosed with Crohn's disease, according to the Crohn's and Colitis Foundation of America and the European Federation of Crohn's and Ulcerative Colitis Associations (EFCCA).

About Isis Pharmaceuticals, Inc.

Isis Pharmaceuticals, Inc. is exploiting its expertise in RNA to discover and develop novel human therapeutic drugs for its pipeline and for its partners. The company has successfully commercialized the world's first antisense drug and has 10 antisense products in development to treat metabolic, cardiovascular, inflammatory and viral diseases, and cancer. Through its Ibis Therapeutics® program, Isis is developing a biosensor to identify infectious organisms, and is discovering small molecule drugs that bind to RNA. As an innovator in RNA-based drug discovery and development, Isis is the owner or exclusive licensee of more than 1,400 issued patents worldwide. Additional information about Isis is available at http://www.isispharm.com.

This press release includes forward-looking statements regarding the development, therapeutic potential and safety of alicaforsen for Crohn's disease and for ulcerative colitis. Any statement describing our goals, expectations, intentions or beliefs is a forward-looking statement and should be considered an at-risk statement, including those statements that are described as Isis' clinical goals. Such statements are subject to certain risks and uncertainties, particularly those inherent in the process of developing technology, in discovering and commercializing drugs that are safe and effective for use as human therapeutics, and in the endeavor of building a business around such products. Actual results could differ materially from those discussed in this press release. As a result, you are cautioned not to rely on these forward-looking statements. These and other risks concerning Isis' research and development programs are described in additional detail in Isis' Annual Report on Form 10-K for the year ended December 31, 2003, and quarterly report on Form 10-Q for the quarter ended September 30, 2004, which are on file with the U.S. Securities and Exchange Commission. Copies of these and other documents are available from the company.

Ibis Therapeutics® is a registered trademark of Isis Pharmaceuticals, Inc.

SOURCE Isis Pharmaceuticals
12/02/2004
CONTACT: Investor Relations & Corporate Communications, Kristina Peterson, or Alison Trollope, both for Isis Pharmaceuticals, 760-603-2331
Web site: http://www.isispharm.com
(ISIS)

12/02/2004 06:30 EST http://www.prnewswire.com