A late-stage trial of Bayer's riociguat in patients with pulmonary arterial hypertension has hit its targets, pushing the drug closer to regulatory submission.

The German drugmaker has unveiled top-line data from the PATENT-1 study, revealing that it met its primary endpoint of showing a significant improvement in the six-minute walk distance (6MWD) test compared to placebo in patients with the condition.

In the trial, 443 patients were randomised to receive either one of two riociguat doses or a placebo, and while specific data have not yet been released, the group said that patients taking its drug had an improvement in their walking distance of 36 metres after 12 weeks.

Statistically significant improvements were also recorded across a range of secondary endpoints, including pulmonary vascular resistance and time to clinical worsening, while a positive trend was observed on quality of life measures, it noted. 

The drug - the first of a novel class of compounds that stimulate soluble guanylate cyclase - also seems to have fared well on the safety side, with the most frequently reported side effects including headache, dizziness and peripheral oedema.

PAH is a progressive disease that can lead to heart failure and death.

“The six-minute walk test is a key indicator for improved outcomes in patients with PAH and, therefore, the positive results of the PATENT-1 trial are encouraging,” said Professor Ardeschir Ghofrani, University Hospital Giessen and Marburg, Germany and Principal Investigator of the PATENT study, commenting on the results. 

Bayer said it is also "optimisitic" about the potential of the drug, and it plans to file for marketing approval during the first half of 2013.