MYOG Myogen

Myogen, Inc. (Nasdaq: MYOG), a biopharmaceutical company focused on the discovery, development and commercialization of small molecule therapeutics for the treatment of cardiovascular disorders, today announced that a scientific presentation describing the effects of ambrisentan in patients with pulmonary arterial hypertension (PAH) was given at ATS 2006 -- San Diego, the annual International Conference of the American Thoracic Society. The oral presentation highlighted efficacy and safety results from ARIES-2, the Phase 3 trial of ambrisentan in 192 patients with PAH. The data demonstrate that ambrisentan improved exercise capacity, delayed clinical worsening and improved symptoms in patients with PAH. Ambrisentan was well tolerated and was not associated with any clinically significant serum aminotransferase abnormalities or drug-drug interactions with warfarin-type anticoagulants. Myogen reported the top line results of the trial in December 2005. Horst Olschewski, M.D., presented "Ambrisentan Improves Exercise Capacity and Time to Clinical Worsening in Patients with Pulmonary Arterial Hypertension: Results of the ARIES-2 Study." Dr. Olschewski is Professor of Medicine, Division of Pulmonology, Medical University Graz, Austria and a principal investigator for ARIES-2. Patients in this trial were primarily women (75%). The etiology of the PAH was 65% idiopathic and 35% associated with other causes. Patients entered the trial in World Health Organization (WHO) Functional Class I/II (47%) and Class III/IV (53%). The patients were enrolled from Western Europe/Israel (52%), Eastern Europe (24%) and South America (24%). Mean six-minute walk distance (6MWD) at baseline was 348 meters +/- 84 meters. The primary efficacy endpoint of the ARIES-2 trial was the placebo-corrected mean change in 6MWD at week 12 compared to baseline. Results of the trial demonstrated that with once-daily dosing, 5 mg of ambrisentan improved the placebo-corrected mean 6MWD by 59.4 meters (p = 0.0002) and 2.5 mg of ambrisentan improved the placebo-corrected mean 6MWD by 32.3 meters (p = 0.0219). For the placebo group, the mean 6MWD at week 12 decreased from baseline by 10.1 meters. Improvements in time to clinical worsening compared to placebo were observed for both the 5 mg dose group (p=0.0076) and the 2.5 mg dose group (p=0.0048). Improvements in Borg dyspnea index compared to placebo were observed for both the 5 mg dose group (p = 0.0384) and the 2.5 mg dose group (p=0.0367). Improvements in SF-36 Health Survey(R) compared to placebo were observed for both the 5 mg dose group (p=0.040) and the 2.5 mg dose group (p=0.005). The pre-specified analysis of WHO functional class did not reach statistical significance; however, deterioration of at least one class was observed in 18% of placebo patients, compared to 5% of patients in the 2.5 mg ambrisentan dose group and 3% of patients in the 5 mg ambrisentan dose group. The trial safety results demonstrated ambrisentan was well tolerated. The most frequent adverse event was headache, which occurred in 12.7% of patients in the 5 mg dose group and 7.8% in the 2.5 mg dose group, compared to 6.2% in the placebo group. There were four deaths in the placebo arm compared to two deaths (unrelated to drug) in the 2.5 mg ambrisentan dose group and none in the 5 mg ambrisentan dose group. Ambrisentan had no apparent effect on the activity or dosage of warfarin-type anticoagulants commonly prescribed for patients with PAH. No patients treated with ambrisentan developed serum aminotransferase concentrations greater than three-times the upper limit of the normal range (3xULN), compared to one patient (1.5%) in the placebo group. As of May 2006, patients in the long-term follow-up study have a maximum drug exposure of 2.4 years and a mean drug exposure of one year. During this long-term treatment, the incidence of serum aminotransferase concentrations greater than 3xULN was less than 2% (0.6% confirmed upon re-test). About Myogen Myogen is a biopharmaceutical company focused on the discovery, development and commercialization of small molecule therapeutics for the treatment of cardiovascular disorders. Myogen currently has two product candidates in late-stage clinical development: ambrisentan for the treatment of patients with pulmonary arterial hypertension and darusentan for the treatment of patients with resistant hypertension. Myogen and GlaxoSmithKline have entered into a global PAH collaboration in which Myogen has distribution and marketing rights to GlaxoSmithKline's Flolan (epoprostenol sodium) in the United States and GlaxoSmithKline has sublicensed ambrisentan from Myogen for all territories outside of the United States, where Myogen retains exclusive rights. Myogen also conducts a target and drug discovery research program focused on the development of disease-modifying drugs for the treatment of chronic heart failure and related cardiovascular disorders. Please visit Myogen's website at www.myogen.com. Safe Harbor Statement This press release contains forward-looking statements that involve significant risks and uncertainties, including summary statements relating to the results of the Company's ARIES-2 clinical trial. Actual results could differ materially from those projected and the Company cautions investors not to place undue reliance on the forward-looking statements contained in this release. Results from clinical trials, including the Company's ARIES-2 trial, are not necessarily predictive of future clinical results. Top line results may not be confirmed upon full analysis of the detailed results of a trial and additional information relating to the safety, efficacy or tolerability of the Company's product candidates, including ambrisentan, may be discovered upon further analysis of trial data and upon review and analysis of additional trial data, including data from the Company's ARIES-1 clinical trial and ARIES long-term study. If the Company's product candidates do not meet safety or efficacy endpoints in clinical evaluations, they will not receive regulatory approval and the Company will not be able to market them. Even if the Company's product candidates meet safety and efficacy endpoints, regulatory authorities may not approve them, the Company may not be able to successfully market them, or the Company may face post-approval problems that require the withdrawal of its product from the market. The Company's results may be affected by its effectiveness at managing its financial resources, its ability to successfully develop and market its product candidates, its ability to obtain and enforce patent protection for its products, competition from other biotechnology and pharmaceutical companies, difficulties or delays in manufacturing its products, and regulatory developments involving current and future products. Delays in initiating or conducting clinical trials, whether caused by competition, adverse events, patient enrollment rates, regulatory issues or other factors, could adversely affect the Company's financial position and prospects. If the Company is unable to raise additional capital when required or on acceptable terms, it may have to significantly delay, scale back or discontinue one or more of its drug development or discovery research programs. Myogen may not ever have any products that generate significant revenue. Additional risks and uncertainties relating to the Company and its business can be found in the "Risk Factors" section of Myogen's Form 10-K for the year ended December 31, 2005 and Myogen's reports on Form 10-Q and Form 8-K. It is Myogen's policy to only update or reconfirm its public guidance by issuing a press release or filing a periodic or current report with the Securities and Exchange Commission. All information in this press release is as of May 24, 2006. Myogen undertakes no duty or obligation to update any forward-looking statements contained in this release as a result of new information, future events or changes in the Company's expectations.