Nov. 2, 2009 (Business Wire) -- Gilead Sciences, Inc. (Nasdaq:GILD), in collaboration with GlaxoSmithKline (GSK), today 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® (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.
“The question of first-line combination therapy versus monotherapy is one of the most important outstanding clinical questions in PAH,” said Lewis J. Rubin, MD, Professor of Medicine, University of California, San Diego. “As the first large, randomized clinical trial to address the efficacy of initial combination therapy in PAH, AMBITION has the potential to be a landmark study.”
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.
Full prescribing information for Letairis is available at www.gilead.com and at http://www.letairis.com/downloads/LETAIRIS_prescribing_information.pdf.
WARNING: POTENTIAL LIVER INJURY
Letairis can cause elevation of liver aminotransferases (ALT and AST) to at least three times the upper limit of normal (ULN). Letairis treatment was associated with aminotransferase elevations greater than three times ULN in 0.8 percent of patients in 12-week trials and 2.8 percent of patients including long-term open-label trials out to one year. One case of aminotransferase elevations greater than three times ULN has been accompanied by bilirubin elevations greater than two times ULN. Because these changes are a marker for potentially serious liver injury, serum aminotransferase levels (and bilirubin if aminotransferase levels are elevated) must be measured prior to initiation of treatment and then monthly.
Elevations in aminotransferases require close attention. Letairis should generally be avoided in patients with elevated aminotransferases greater than three times ULN at baseline because monitoring liver injury may be more difficult. If liver aminotransferase elevations are accompanied by clinical symptoms of liver injury (such as nausea, vomiting, fever, abdominal pain, jaundice, or unusual lethargy or fatigue) or increases in bilirubin greater than two times ULN, treatment should be stopped. There is no experience with the re-introduction of Letairis in these circumstances.
CONTRAINDICATION: PREGNANCY
Letairis is very likely to produce serious birth defects if used by pregnant women, as this effect has been seen consistently when it is administered to animals.
