Actelion Pharmaceuticals US, Inc. Tracleer(R) Shows Clinical Benefit as Combination Therapy with Sildenafil for Pulmonary Arterial Hypertension

CHICAGO, Oct. 23 /PRNewswire/ -- Actelion Pharmaceuticals US, Inc. today announced positive results from two trials demonstrating that Tracleer(R) (bosentan) may be safe and effective as a combination therapy for the treatment of pulmonary arterial hypertension (PAH). Data from both studies suggest that Tracleer, when given in combination with sildenafil, is well-tolerated and improves hemodynamics in PAH patients. The data were presented at CHEST 2007, the annual meeting of the American College of Chest Physicians, taking place in Chicago.

COMPASS-1 (Effects of Combination Of bosentan and sildenafil versus sildenafil Monotherapy on morbidity and mortality in symptomatic PAtientS with pulmonary arterial hypertenSion) was the first clinical trial to provide detailed hemodynamic information on the combination of Tracleer and sildenafil, and showed that the combination of acute oral sildenafil together with long-term Tracleer therapy significantly reduced pulmonary vascular resistance (PVR).

Data from the sildenafil cohort of the Phase 3 EARLY (Endothelin Antagonist tRial in miLdlY symptomatic PAH patients) study showed that Tracleer improved hemodynamics and suggested a delay in disease progression in sildenafil-treated mildly symptomatic PAH patients. The EARLY trial was the first study of its kind to evaluate the benefit of Tracleer and sildenafil combination therapy.

"Despite the availability of effective PAH therapies, we are not meeting key treatment goals for long-term stabilization in the majority of patients," said Nazzareno Galie from the University of Bologna, Italy, also the lead author of the COMPASS-1 study. "Given the progressive and destructive nature of this disease, combining therapies with different modes of action has become an important focus for research, and these results support our belief that adding bosentan to sildenafil could potentially slow disease progression."

"The results of the COMPASS-1 and EARLY studies demonstrate that Tracleer, when used alone or in combination with other therapies, appears to be well-tolerated and an effective treatment option for patients with PAH," said Craig Hopkinson, vice president of U.S. medical at Actelion. "Actelion is committed to conducting studies with Tracleer in combination with other approved therapies in order to evaluate the drug's effect in a combination therapy setting on delaying disease progression and improving patient care."

COMPASS-1 Study Details and Results

The COMPASS-1 trial assessed the acute hemodynamic effects of sildenafil in combination therapy with Tracleer. The open-label, uncontrolled, prospective, multicenter study evaluated 45 patients receiving Tracleer and measured PVR with the addition of inhaled nitric oxide (iNO) and a single 25mg dose of sildenafil.

The % change in PVR induced by iNO and sildenafil was similar. Sildenafil lowered mean PVR by 15.1% from 828+/-724 to 721+/-651 dyne.s.cm-5 60 minutes after intake (p<0.0001). iNO was shown to reduce mean PVR by 14.9% from 807+/-635 to 745+/-740 dyne.s.cm-5 after inhalation (p<0.0001).

EARLY Study Details and Results

The EARLY trial evaluated the safety and efficacy of Tracleer in mildly symptomatic (WHO Functional Class II) PAH patients. This randomized, double-blind, placebo-controlled trial (n=185) assessed the efficacy of Tracleer as a monotherapy and as a combination therapy in patients receiving background sildenafil treatment (n=29).

Mean baseline PVR was higher in patients receiving sildenafil than in patients not taking sildenafil; and six-minute walk distances were similar at baseline. At six months, patients treated with Tracleer (in sildenafil and non-sildenafil subgroups) both saw a reduction in PVR (-20%, P=0.0478 sildenafil; -23%, P<0.0001 no sildenafil).

Data from the trial also suggest that Tracleer is effective in early stage PAH patients as a monotherapy.

About Tracleer(R) in Pulmonary Arterial Hypertension (PAH)

Tracleer(R) (bosentan), the first oral dual endothelin receptor antagonist, is approved for the treatment of pulmonary arterial hypertension (PAH) and made available by Actelion Ltd. subsidiaries in the United States, the European Union, Japan, Australia, Canada, Switzerland and other markets worldwide.

Tracleer requires attention to two significant safety concerns: potential for serious liver injury (including rare cases of liver failure and unexplained hepatic cirrhosis in a setting of close monitoring) and high potential for major birth defects. Liver monitoring of all patients is essential prior to initiation of treatment and monthly thereafter. Pregnancy must be excluded and prevented by two forms of birth control; monthly pregnancy tests should be obtained. Because of these risks, Tracleer is only supplied through a controlled distribution system.

About Actelion Pharmaceuticals

Actelion Pharmaceuticals has pioneered research and development in the pulmonary arterial hypertension (PAH) disease area. More than 40,000 PAH patients have been prescribed Actelion's product Tracleer(R) (bosentan), an orally available dual endothelin receptor antagonist for patients with World Health Organization (WHO) Class III or IV PAH in the U.S., and Class III PAH in Europe. Tracleer was approved in 2001 as the first oral treatment for PAH, and is currently approved in the U.S., the European Union, and other markets worldwide. In January 2007, Actelion acquired CoTherix, Inc., whose product Ventavis(R) (iloprost) Inhalation Solution is approved and marketed in the United States for the treatment of patients with WHO Class III or IV PAH.

CONTACT: Danielle Bertrand of WeissComm Partners, +1-415-946-1056,
dbertrand@wcpglobal.com, for Actelion Pharmaceuticals US, Inc.