Gilead May Gain the Advantage on Its Foes

Gilead Sciences' (GILD) chief scientific officer said Monday that the U.S. Food and Drug Administration might not require regular liver safety monitoring for patients taking ambrisentan, the company's experimental drug for the treatment of pulmonary arterial hypertension, or PAH.

The absence of a so-called "black box label" for ambrisentan would be a huge marketing advantage for Gilead over its competitors, most notably Swiss drugmaker Actelion and U.S. biotech firm Encysive Pharmaceuticals (ENCY).

The FDA is expected to issue its approval decision for ambrisentan on or before June 18. In an interview Monday, Gilead's Chief Scientific Officer Norbert Bischofberger said the company and regulators are currently negotiating over the language in the ambrisentan label.

Asked if he believed the FDA will require liver monitoring in the ambrisentan label, Bischofberger said, "I don't think it should be in there."

While Bischofberger was careful to say that the FDA would make the final call and that labeling discussions are not complete, he noted his belief that safety data collected and presented to regulators to date clearly show that ambrisentan doesn't cause liver toxicity, and in fact, the drug probably ameliorates the problem in patients with pulmonary arterial hypertension.

"This is the most important data point for clinicians that differentiates our drug [ambrisentan] from the others," said Bischofberger.

How Competitors Stack Up

At present, the approved FDA label for Actelion's Tracleer is topped by a strong warning about the drug's potential to cause serious liver damage. For that reason, Tracleer patients are required to undergo monthly monitoring for liver toxicity. Actelion reported 2006 worldwide Tracleer sales of $730 million in 2006. First-quarter sales topped $210 million, putting the drug on an $800 million sales run rate for the current year.