Archemix Corp., a privately-held biotechnology company working to develop aptamer-based therapeutics, announced that it has initiated a phase 2b clinical trial of its novel anti-von Willebrand Factor (vWF) aptamer, ARC1779.

Archemix also announced that as part of a transition plan, Duncan Higgons, formerly the executive vice president of business operations, will become president and interim chief executive officer. Errol De Souza, who previously served as chief executive officer, will continue as a member of the board of directors of Archemix.

In addition, Archemix announced that it has received notice from NitroMed that NitroMed has received a superior offer and has accordingly terminated the merger agreement between the parties.

"Archemix is, and continues to be, in a very strong position and will continue to pursue our business strategy fully, in order to maximize the potential of aptamers as a new therapeutic class," said Peter Barrett, Ph.D. Partner at Atlas Venture and the Lead Director of the Archemix Board of Directors. "The strength of Archemix's business is evidenced by the company's recently-announced $1.4 billion collaboration with GlaxoSmithKline, a strong balance sheet, and clinical progress with ARC1779, our lead aptamer product candidate in Phase 2 clinical trials. We are confident in our future, as Archemix has the resources to support and fund its business plan."

Archemix also announced that it has started a phase 2b clinical trial of its anti-von Willebrand Factor (vWF) aptamer, ARC1779. This trial is designed to evaluate the safety and efficacy of ARC1779 as a potential first-in-class anti-platelet agent in patients suffering from a group of rare, life-threatening blood disorders known as thrombotic microangiopathies, or TMA, a condition for which there is currently no specifically approved drug treatment. The Phase 2b trial with ARC1779 is the most advanced aptamer product candidate within Archemix's portfolio of aptamers. Archemix is also developing aptamer product candidates for other rare haematological disorders, including sickle cell disease and haemophilia.

"We are aggressively moving forward with our clinical program for ARC1779, as well as making progress with our other proprietary aptamers for rare haematological disorders," said Duncan Higgons, Chief Operating Officer and interim Chief Executive Officer of Archemix. "The significant progress and investment that is being made for aptamer therapeutics across many fronts - both within Archemix and by our licensees who are currently evaluating five different aptamer product candidates in human clinical trials, two in Phase 2 and three in Phase 1 - gives us great confidence in the future for Archemix and for the potential of aptamers to deliver breakthrough medicines for patients."

The recently initiated phase 2b trial is a randomized, double-blind, placebo-controlled, dose ranging study to evaluate the efficacy, safety and tolerability of ARC1779 in approximately 100 TMA patients at multiple centres in North America and Europe. The primary endpoint of the Phase 2b trial is clinical outcome defined as a composite of clinical events resulting from injury to the target organs commonly affected by TMA, including the brain, heart, and kidneys. Enrolled patients will receive either one of three different doses of ARC1779 administered intravenously, or placebo. The study is designed to enrol patients with any form of TMA, including those with familial TTP, idiopathic acquired TTP, haemolytic uremic syndrome, or HUS, or TMA related to malignancy or autoimmune diseases.

"TMA is a devastating group of diseases and with no approved drug therapy there continues to be a high unmet medical need for an effective and well tolerated treatment," commented Dr. Bernd Jilma of the University of Vienna, the lead investigator in the Phase 2a trial. "The research already conducted in the Phase 2a trial characterized the effects of ARC1779 in its fundamental mechanism of action to modulate vWF function, and informed us about the optimized regimen for administration of ARC1779 in TMA patients."

Initiation of the phase 2b trial is based on successful completion of a Phase 2a trial that assessed ARC1779's activity in the presence of the excessive activity of the protein vWF, measured by changes in vWF activity, platelet count and vWF-related platelet function after administration of ARC1779 in 20 patients. Initial data from the phase 2a trial were presented at the American Society of Haematology meeting in San Francisco in December 2008.

Thrombotic microangiopathies, or TMA, is a group of rare, life-threatening blood disorders for which there is currently no approved drug treatment. Acute episodes of TMA are associated with a significant mortality rate, and based on published case studies, Archemix believes that the mortality rate for patients with thrombotic thrombocytopenic purpura, or TTP, which accounts for most of the patients with TMA, is up to approximately 20%. TMA is caused by failure of regulation of the activity of the protein known as von Willebrand Factor, or vWF, which under normal conditions plays a key role in protecting the body from bleeding. In patients with TMA, an increase in vWF activity results in the formation of excessive blood clots which block the arterial circulation and cause injury to key organs, including the brain, heart and kidneys. These morbidities include stroke, seizure, kidney failure or heart attack.

Archemix's lead aptamer product candidate, ARC1779, is a PEGylated aptamer consisting of 40 nucleotides for the treatment of TMA. ARC1779 is designed to inhibit the function of a protein called von Willebrand Factor, or vWF, which, when activated, is responsible for the adhesion, activation and aggregation of platelets. ARC1779 has received orphan designation for the treatment of TTP in both the United States and the European Union.

Aptamers are synthetically-derived oligonucleotides, or short nucleic acid sequences, that bind to protein targets with high affinity and specificity and can be designed to have a specified duration of action. Aptamers represent an emerging class of potential therapeutic agents that Archemix believes may have broad application to treat a variety of human diseases.

Archemix is a biotechnology company focused on discovering, developing and commercializing aptamer therapeutics. Using Archemix's processes for discovering aptamers, which are protected by its broad patent portfolio, Archemix is developing aptamer product candidates for rare haematological diseases.