CAMBRIDGE, Mass. & CARLSBAD, Calif.
August 7, 2007

Archemix Corp. and Isis Pharmaceuticals, Inc. (Nasdaq:ISIS) announced today that they have entered into a strategic alliance that includes a broad intellectual property license agreement and research collaboration. The agreement provides Archemix with access to approximately four hundred issued and pending Isis patents covering proprietary chemistries, analytical methods and manufacturing methods related to the research, development and commercialization of oligonucleotide-based therapeutics to discover and develop drugs based on Archemix's proprietary SELEX technology. Additionally, the companies will share their respective know-how in oligonucleotide therapeutic discovery and development.

This alliance capitalizes upon Isis' significant investment in the research and development of oligonucleotide therapeutics. Under the terms of the agreement, Isis licensed to Archemix certain of Isis' patents relating to oligonucleotide compositions and methods exclusively for use in conjunction with aptamer therapeutics. Isis will receive milestones and royalties on aptamer therapeutics developed by Archemix that incorporate proprietary Isis chemistries or which utilize proprietary Isis analytical or manufacturing methods. Additionally, Isis will receive a percentage of revenue generated by Archemix if Archemix sublicenses Isis' intellectual property to a third party for the development of aptamer therapeutics. Isis also received a warrant to purchase an undisclosed number of shares of Archemix common stock. Specific financial terms were not disclosed.

About Aptamers
Aptamers are synthetically-derived oligonucleotides, or short nucleic acid sequences. Aptamers represent an emerging class of potential therapeutic agents that Archemix believes may have broad application to treat a variety of human diseases. Archemix believes that aptamer therapeutics combine many of the beneficial characteristics of biologics, small molecules and other classes of oligonucleotides, such as antisense and small interfering RNA, or siRNA, without exhibiting many of their disadvantages. Aptamers have the ability to disrupt interactions between proteins, bind with high affinity and specificity to their targets and can be designed to have a specified duration of action.

About Archemix
Archemix is a biotechnology company focused on discovering, developing and commercializing aptamer therapeutics. Using Archemix’s proprietary processes for discovering aptamers, which are protected by its patent portfolio, Archemix is developing aptamer product candidates for cardiovascular and hematological diseases and cancer. Archemix has completed a Phase 1 clinical trial for ARC1779, its lead aptamer product candidate and, subject to regulatory review of its proposed protocol, Archemix expects to commence Phase 2a and Phase 1b clinical trials of ARC1779 in two distinct indications in the fourth quarter of 2007. In addition, Archemix has licensed its intellectual property to third parties to develop their own aptamer product candidates. To date, Archemix has licensed its intellectual property to discover or develop aptamer product candidates to nine biotechnology and pharmaceutical companies, including Pfizer, Merck Serono, Takeda Pharmaceuticals and Elan Pharma. Archemix expects two of these aptamer product candidates being developed by third parties to enter Phase 2 clinical trials in the second half of 2007.

About Isis Pharmaceuticals, Inc.
Isis is exploiting its expertise in RNA to discover and develop novel drugs for its product pipeline and for its partners. The Company has successfully commercialized the world's first antisense drug and has 17 drugs in development. Isis' drug development programs are focused on treating cardiovascular and metabolic diseases. Isis' partners are developing drugs for cancer, and inflammatory and other diseases. Ibis Biosciences, Inc., Isis' wholly owned subsidiary, is developing and commercializing the Ibis T5000(TM) Biosensor System, a revolutionary system to identify infectious organisms. As an innovator in RNA-based drug discovery and development, Isis is the owner or exclusive licensee of over 1,500 issued patents worldwide. Additional information about Isis is available at www.isispharm.com.

This press release includes forward-looking statements regarding Isis' intellectual property estate and proprietary technologies for discovery and development of aptamer drugs, and the potential success of its collaboration with Archemix. Any statement describing Isis' goals, expectations, financial or other projections, intentions or beliefs is a forward-looking statement and should be considered an at-risk statement, including those statements that are described as Isis' goals. Such statements are subject to certain risks and uncertainties, particularly those inherent in the process of discovering, developing and commercializing drugs that are safe and effective for use as human therapeutics, and in the endeavor of building a business around such products. Isis' forward-looking statements also involve assumptions that, if they never materialize or prove correct, could cause its results to differ materially from those expressed or implied by such forward-looking statements. Although Isis' forward-looking statements reflect the good faith judgment of its management, these statements are based only on facts and factors currently known by Isis. As a result, you are cautioned not to rely on these forward-looking statements. These and other risks concerning Isis' programs are described in additional detail in Isis' annual report on Form 10-K for the year ended December 31, 2006, and its quarterly report on Form 10-Q for the quarter ended March 31, 2007, which are on file with the SEC. Copies of these and other documents are available from the Company.