Shares in Encysive surged 39% to close at $7.01 yesterday, after news that US regulators will go ahead with a “Class 1” review of its lead drug Thelin sparked a frenzied bout of trading on the Nasdaq.
The group suffered a major setback earlier this year when the Food and Drug Administration unexpectedly issued an approvable letter for Thelin (sitaxsentan sodium) as a treatment for pulmonary arterial hypertension instead of the anticipated all clear, a move which swiped around 50% off Encysive's share price.
But now the FDA’s requests outlined in the letter have been satisfied, the drug has taken a significant step towards market entry. And this is the second piece of good news for Thelin in as many weeks, as the European Medicines Agency’s Committee for Human Medicines and Products recently recommended the drug for approval.
It had been feared that Thelin’s delay in the US would see it lose its first-to-market advantage over Myogen’s rival drug ambrisentan, which was granted a priority review by US regulators in March. But in light of this development, Encysive’s drug could still make it first onto the potentially highly-lucrative US market, depending on the speed of the FDA’s review. However, this seemed to have a muted effect on Myogen, its shares dipping just $0.12 to $29.57 on the news.