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Gilead Sciences Inc. in collaboration with GlaxoSmithKline announced plans for an international, event-driven (morbidity and mortality) clinical trial to study combination therapy versus monotherapy in a first-line treatment setting for pulmonary arterial hypertension (PAH). The study, AMBITION (a randomized, double-blind, multicenter study of first-line combination therapy with AMBrIsentan and Tadalafil in subjects with pulmonary arterial hypertensION), will evaluate first-line combination use with ambrisentan, an endothelin receptor antagonist (ERA) and tadalafil, a PDE5 inhibitor, in patients with PAH. Ambrisentan is approved under the tradename Letairis(R) (ambrisentan 5 mg and 10 mg tablets) as a once-daily treatment for PAH (WHO Group 1) in patients with WHO functional class II or III symptoms to improve exercise capacity and delay clinical worsening. AMBITION will be a double-blind, multicenter study, in which more than 300 treatment-naive PAH patients will be randomized to receive either the combination of ambrisentan and tadalafil or monotherapy (ambrisentan or tadalafil). Gilead and GSK are working with regulatory agencies and the PAH research community to finalize details of the study and plan to begin enrollment in 2010.

Gilead Sciences Inc. announced the presentation of three-year (144-week) open label data from two pivotal Phase III clinical trials, Studies 102 and 103, evaluating the safety and efficacy of once-daily Viread(R) (tenofovir disoproxil fumarate) among adult patients with chronic hepatitis B virus (HBV) infection. These data will be presented at the annual meeting of the American Association for the Study of Liver Diseases (The Liver Meeting 2009) being held this week in Boston, October 30-November 3. These new data show that the majority of patients who received Viread for up to 144 weeks experienced sustained suppression of HBV DNA levels in the blood to below 400 copies/mL (87% in Study 102 and 71% in Study 103). Additionally, cumulatively over 144 weeks, 8% of all patients in Study 103 (HBeAg-positive) experienced 's' antigen (HBsAg) loss, which can contribute to resolution of chronic hepatitis B infection. Notably, no mutations associated with resistance to Viread developed in any patients up to 144 weeks of treatment. Clinical practice guidelines recommending Viread as a first-line therapy for the treatment of chronic hepatitis B were issued earlier this year by both the American Association for the Study of Liver Diseases and the European Association for the Study of the Liver. The U.S. Food and Drug Administration (FDA) approved Viread for chronic hepatitis B in adults in 2008 based on earlier (48-week) results from Studies 102 and 103, and recently approved the inclusion of 96-week data in the product's label.