Bayer has been boosted by the news that regulators in the USA are fast-tracking the German group's investigational pulmonary arterial hypertension riociguat.

The US Food and Drug Administration has granted priority review to the New Drug Application for riociguat, which Bayer filed in February on both sides of the Atlantic for PAH and a related condition, inoperable chronic thromboembolic pulmonary hypertension (CTEPH). The FDA bestows a priority review on medicines that offer major advances in care or that provide a treatment where no adequate therapy exists. The agency aims to complete its assessment within eight months from the submission of the NDA, rather than the standard 12 months.

The submissions are based on two Phase III studies and riociguat, the first member of a novel class of compounds called stimulators of soluble guanylate cyclase (sGC), met its primary endpoint in both trials, a change in exercise capacity after 12- or 16 weeks respectively. The drug was generally well tolerated, with a good safety profile.

Kemal Malik, head of global development at Bayer Healthcare, noted that "to date, no approved pharmacological therapy exists for CTEPH and as a result there is an urgent unmet medical need for patients who are unable to undergo surgery. We hope that we will soon be in a position to provide patients and doctors with a new treatment option".

If approved, riociguat would be going up against Actelion's Tracleer (bosentan) and Gilead Sciences/GlaxoSmithKline's Letairis/Volibris (ambrisentan). Actelion, which has dominated the PAH market, has already filed its follow-up to Tracleer, Opsumit (macitentan).