MYOGEN ANNOUNCES ACHIEVEMENT OF TARGET ENROLLMENT FOR ARIES-1 TRIAL

Myogen has announced the achievement of target enrollment of 186 patients in ARIES-1, one of the company's two pivotal Phase III trials of ambrisentan in patients with pulmonary arterial hypertension (PAH). A number of additional patients are in screening, and the company will allow those patients to complete the process and either be randomized into the trial or disqualified, in accordance with the trial protocol.

In January 2004, Myogen initiated two Phase III trials, ARIES-1 and ARIES-2, evaluating the safety and efficacy of ambrisentan in patients with PAH. The ARIES trials are randomized, double-blind, placebo-controlled trials of identical design except for the doses of ambrisentan and the geographic locations of the investigative sites. Both trials were designed to enroll 186 patients (62 patients per dose group). ARIES-1 evaluates once daily doses of 5 mg and 10 mg of ambrisentan, and ARIES-2 evaluates once-daily doses of 2.5 mg and 5 mg of ambrisentan. The primary efficacy endpoint is exercise capacity, measured as the mean change from baseline at 12 weeks in a six-minute walk test compared to placebo.