Eli Lilly said it is suspending two small studies of its most promising pipeline candidate, the blood-thinner prasugrel, after data raised concerns about the dosage used in certain patient groups.
The drugmaker said the studies would be put on hold until procedures can be adjusted.
Lilly is scheduled to present major late-stage trial data on prasugrel to the American Heart Association on Nov. 4.
"The protocol amendments should not be interpreted to represent the outcome of the overall prasugrel clinical development program," Lilly said in a statement.
However the suspension of the studies has raised eyebrows on Wall Street where the development of prasugrel is being closely watched.
“The suspended dosing does suggest a problem of some sort in at least a certain population of patients,” said Sanford C. Bernstein & Co. global pharmaceuticals analyst Tim Anderson in a research note. “Lilly is not answering some important questions…for example, they are not saying what exactly the clinical issue was that led to suspended dosing.”
According to Anderson, there is a 60/40 chance that prasugrel will see an approval -- likely in 2009.
Prasugrel will however have a difficult time unseating Bristol-Myers Squibb and Sanofi-Aventis' deeply entrenched Plavix, Anderson predicts. He forecasts total prasugrel sales of $1.6B by 2012, if the drug makes it to market.