BioCentury's websites will be down for upgrades starting at 9 p.m. PDT on Monday, August 26. We expect the downtime to last no more than 6 hours, and we apologize for any inconvenience.

12:00 AM
Mar 14, 2011
 |  BioCentury  |  Strategy

Letairis LEAPS Forward

Gilead's Letairis set to gain on Actelion's Tracleer, but patent window short

Letairis ambrisentan was the driver of Gilead Sciences Inc. $2.5 billion cash acquisition of Myogen Inc. in 2006. But like Tracleer bosentan from Actelion Ltd., Letairis ended up with a boxed warning about the risk of liver injury.

As a result, Tracleer's six-year head start made it the leading endothelin receptor antagonist (ERA) in pulmonary arterial hypertension, and Gilead has struggled to differentiate Letairis in the marketplace.

Letairis now has a new label - without a boxed warning about liver injury - which could change the competitive picture. But Gilead needs to work quickly; the drug could begin to lose patent exclusivity as early as 2015.

In the beginning, Gilead had expected Letairis would be best in class (see BioCentury, Oct. 9, 2006).

The compound had completed a pair of successful Phase III trials to treat PAH. It offers once-daily dosing, whereas Tracleer is taken twice daily. And unlike Tracleer, Letairis is not metabolized by cytochrome P450 and was thus expected to have fewer drug-drug interactions.

Above all, liver safety was going to be the key selling point, as clinical trials of Letairis had shown much lower rates of abnormal liver function.

Tracleer was approved in 2001 with a black box warning stating that 11% of patients in clinical studies had elevations of liver aminotransferases at least three times the upper limit of normal (3x ULN). This was accompanied by elevated bilirubin in a small number of cases.

As a result, patients receiving Tracleer must have their liver aminotransferase levels tested before beginning...

Read the full 1272 word article

User Sign in

Trial Subscription

Get a 4-week free trial subscription to BioCentury

Article Purchase

$150 USD
More Info >