Actelion has been boosted by the news that regulators in the USA have given the green light to Opsumit, the Swiss biotech's follow-up to the pulmonary arterial hypertension blockbuster Tracleer.

The agency has approved Opsumit (macitentan) based on a trial where 742 participants were randomly assigned to take the drug or placebo. The average treatment duration was about two years and Opsumit was seen to be effective in delaying disease progression.

Opsumit is an oral dual endothelin receptor antagonist and similar to other members of its drug class, it carries a boxed warning that the drug should not be used in pregnant women because it can harm the developing foetus.
Actelion hopes the drug will replace Tracleer (bosentan), which makes up the vast majority of its turnover but goes off-patent in 2015; sales of the latter for the first nine months of 2013 increased 3% to 1.14 billion Swiss francs.

Chief executive Jean-Paul Clozel said Opsumit represents "a unique treatment option, the only oral PAH medicine that has proven to delay disease progression". He added that Actelion has been developing Opsumit for the last 14 years, saying "we will now leverage our existing PAH expertise and infrastructure" to launch the drug "within the coming weeks".
The other key player in the PAH market is Gilead Sciences, which markets Letairis (ambrisentan), while the FDA recently approved Bayer's Adempas (riociguat) for PAH and for patients with chronic thromboembolic pulmonary hypertension.