A US Food and Drug Administration (FDA) advisory committee voted unanimously yesterday to recommend approval of riociguat, a drug developed by Bayer as a treatment for pulmonary arterial hypertension (PAH).
Riociguat had a fairly easy ride through the panel meeting - backing the drug for both PAH and a related condition called chronic thromboembolic pulmonary hypertension (CTEPH) that is currently only treatable via a surgical procedure known as pulmonary endarterectomy - although FDA reviewers raised some issues about the starting dose used.
Bayer is seeking approval for a 2.5mg dose of riociguat, but the agency has suggested it may be preferable to start patients on a lower dose and raise it if treatment is not effective. In documents released ahead of the meeting, the FDA said the drug was "approvable, as long as its dosing algorithm is modified".
Bayer sponsored two clinical trials to assess the safety and efficacy of riociguat, which has the proposed trade name of Adempas and has been given a priority review in the US.
PATENT-1 evaluated riociguat in patients with symptomatic PAH, while CHEST-1 evaluated the drug in patients with CTEPH for whom pulmonary endarterectomy was ineffective or who were ineligible for surgery.
Bayer chief executive Wolfgang Plischke said last month that the company had been building up inventory for a launch ahead of the advisory committee meeting because the company is "optimistic" that it will be able to launch before the end of the year. The FDA's deadline for completing the review is in October 2013.
Riociguat acts via a new mechanism of action - guanylate cyclase (sGC) stimulation - and is one of five drugs highlighted by Bayer as having the potential to achieve collective sales of €5.5bn over the next few years.
Riociguat is predicted to bring in upwards of €500m a year at peak, despite increasing competition in the PAH marketplace, which is currently led by endothelin receptors such as Actelion's Tracleer (bosentan) and Gilead Sciences' Letairis (ambrisentan).
The market for PAH is growing fast due to increased awareness improving patient diagnosis and the launch of new products, and was worth around $3.3bn in 2011, according to GlobalData, although the size of the market is expected to shrink as first-generation treatments - including Tracleer - go off patent.
Other treatments for PAH that will lose patent protection in the coming years include prostacyclin agonists like United Therapeutics' Remodulin (treprostinil) and Actelion's Ventavis (iloprost) and phosphodiesterase-5 inhibitors such as Revatio (sildenafil) and United's Adcirca (tadalafil), and GlobalData sees riociguat eventually leading the market with peak sales of around $700m.
It could also face competition from other first-in-class entrants, such as Actelion's oral prostacyclin receptor antagonist selexipag, as well as Tracleer follow-up Opsumit (macitentan), which has less potential for liver side effects than its parent compound.