Gilead Sciences secured approval for its pulmonary arterial hypertension treatment Letairis (ambrisentan) last week. The drug has an increased safety profile over existing therapies (namely Actelion's Tracleer). Initially developed by the Colorado biotech firm Myogen, Letairis came into the Gilead fold after Myogen was bought out last fall.
Meanwhile, Encysive received an approvable letter for its PAH treatment Thelin (sitaxsentan)…again. For those keeping score at home, this was number three on the approvable letter front. And unlike baseball, Thelin doesn’t get to walk. Who's on first at Encysive?
The FDA has requested an additional study of the drug and Encysive plans to talk it over with the FDA (because talking about it went so well for them the last two times).
I can’t ever recall a drug having this much difficulty in getting approved. Ultimately I’m sure the drug will (eventually) get approved, but it might be after I’m long dead and gone.