(Adds analyst comments; updates stock movement)
By Esha Dey
BANGALORE Feb 9 (Reuters) - ViroPharma Inc VPHM.O said its experimental antiviral compound, maribavir, failed to meet the main goal of a late-stage study in patients who have had bone marrow transplants, hammering its shares down 60 percent to their lowest in more than three years.
Maribavir failed to reduce the incidence of cytomegalovirus (CMV) disease compared with a dummy drug, the company said.
The study also failed to meet the key secondary endpoints.
"The mid-stage data were really impressive, but the late stage is a complete failure. There is no hint at all if the drug is actually working," Cowen & Co analyst Rachel McMinn said.
Cytomegalovirus is a member of the herpes virus family and is a frequent viral illness after transplants. The company had planned two separate trials for maribavir -- in patients receiving stem cell transplants and in those with solid organ transplants.
Failing in the stem cell transplant study means the company might have to do a third late-stage study to get approval even if the second study is successful, pushing the timeline of the drug further away.
"Instead of launching at the end of 2009 or early 2010, we are now talking about starting a late-stage trial in mid-2010. Then the launch perhaps would be in 2012. And that is if the drug works in the solid organ trial," Cowen's McMinn said.
ViroPharma currently has two drugs in the market, Vancocin, an antibiotic, and Cinryze, a treatment for a potentially fatal genetic disease.
Maribavir is considered to be the crux of the company by analysts as Vancocin is about to go generic and Cinryze is only approved for the prevention of a rare genetic disorder.
"Our analysis suggests that ViroPharma is worth $4 to $5 a share, excluding maribavir. It is probably trading at the best-case scenario right now," McMinn said.
Shares of the company fell to a low of $4.89 before paring some losses to trade down $6.06 at $6.15 Monday afternoon on Nasdaq. (Editing by Deepak Kannan)