Bayer’s pulmonary arterial hypertension (PAH) treatment riociguat has been given by a priority review by the US FDA, setting up a possible approval in the autumn.
If given the green light, the oral drug will enter a market that is currently dominated by injectable therapies from Actelion and Gilead Sciences, although riociguat being considered for approval in an area of the PAH market with no current pharmacological competition.
Riociguat is the first in a new class of drug known as soluble guanylate cyclase (sGC) stimulators, and has been fast-tracked by the FDA for the treatment of inoperable chronic thromboembolic pulmonary hypertension (CTEPH), a condition that is currently only treatable via a surgical procedure known as pulmonary endarterectomy.
In addition to inoperable CTEPH, riociguat is also being reviewed for use in patients for whom surgery has not resolved symptoms, said Bayer.
Kemal Malik, head of global development at Bayer, said that riociguat is “the first drug therapy to demonstrate robust efficacy in two potentially fatal pulmonary hypertension indications.”
Two phase III trials – CHEST-1 and CHEST-2 – have been submitted in support of the marketing application and showed that riociguat was able to improve exercise capacity in CTEPH patients, with a favourable safety profile.
Riociguat is one of five drugs highlighted by the pharma company has having the potential to achieve collective sales of €5.5bn over the next few years, with riociguat alone estimated to be worth upwards of €500m a year at peak.
At the moment, Actelion’s endothelin antagonist Tracleer (bosentan) is the top-selling drug in the overall PAH market with sales of 1.5bn Swiss francs ($1.6bn) last year, followed by Gilead’s Letairis (ambrisentan) which brought in $410m.
The market is set for a shake-up in 2015 when Tracleer and other smaller PAH therapies, such as United Therapeutics’ Remodulin (treprostinil), Actelion’s Ventavis (iloprost) and Pfizer’s Revatio (sildenafil) start to lose patent protection.
Meanwhile, Actelion has filed a Tracleer follow-up, Opsumit (macitentan), which offers an advantage over Tracleer as it lacks the potential for liver damage.