Positive data from a phase II trial with Bayer Schering Pharma's oral agent riociguat for the treatment of two different forms of pulmonary hypertension (PH) - chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH) - were presented at the American Thoracic Society (ATS) international conference in San Diego, USA.

Riociguat is an orally available soluble guanylate cyclase (sGC) stimulator, and is the first of these compounds to be developed in PH.

Results from the multi-centre, open-label, uncontrolled phase II trial, showed that riociguat significantly improved exercise capacity from baseline values in patients with CTEPH and PAH. Riociguat also demonstrated significant effects on pulmonary hemodynamics and improvement of symptoms in patients with CTEPH and PAH.

"Bayer Schering Pharma aims to lead the way in advancing cardio-pulmonary research to address the significant unmet medical need for innovative treatment options in this field," said Kemal Malik, M.D., Head of Global Development and member of the Executive Committee of Bayer HealthCare. The data presented at the ATS meeting serves to further reinforce our expectations for riociguat in patients with CTEPH and PAH," he added.

"Pulmonary hypertension is a severe and life-threatening disease that progresses rapidly and, despite advances in patient care over the last few years, there is still a real need for more efficient therapies," said lead investigator Prof. Hossein Ardeschir Ghofrani, Head of the Pulmonary Hypertension Division, Department of Internal Medicine, University of Giessen, Germany." These findings are a positive step towards improving treatment options for PH patients - the majority of whom are currently still without viable treatment options. This could result in a significant enhancement in the care physicians currently offer their patients."

The data presented at ATS follows an earlier presentation of positive topline phase II findings at the Annual Congress of the European Respiratory Society (ERS) in October 2008. Based on these data, randomised, placebo-controlled phase III trials in CTEPH (CHEST-1, followed by an open-label extension trial, CHEST-2) and PAH (PATENT-1, followed by an open-label extension trial, PATENT-2) were initiated in December 2008, with first results from the study programme currently expected in 2011. In addition to the CHEST and PATENT trials, further phase II studies of riociguat in patients suffering from other forms of PH, such as PH secondary to interstitial lung disease (PH-ILD), are ongoing. First results from the PH-ILD study are currently expected in 2009.

Riociguat (BAY 63-2521) is an oral agent that is currently being investigated in phase III clinical trials as a potentially new approach to treating CTEPH and PAH, two life-threatening types of PH. Riociguat is an orally available soluble guanylate cyclase (sGC) stimulator, and is the first of these compounds to be developed in pulmonary hypertension (PH).

It works through the same signaling pathway as the body's own vasodilating substance, nitric oxide (NO). NO relaxes the musculature in the blood-vessel walls, lowering the pulmonary blood pressure and relieving the heart by modulating the activity of the enzyme sGC.

Riociguat has a dual mode of action: it sensitises sGC to the body's own NO while also directly stimulating sGC independently of NO. This is very important because the NO levels in the pulmonary circulation are decreased in patients with PH. Directly stimulating sGC may avoid the limitations of therapies that involve the use of organic nitrates and other NO donors, such as non-specific interactions of NO with various biomolecules.

Bayer Schering Pharma is a worldwide leading specialty pharmaceutical company. Its research and business activities are focused on diagnostic imaging, general medicine, oncology, specialty medicine and women's healthcare.