(Reuters) - Alnylam Pharmaceuticals Inc's stock soared more than 50 percent after the company reported that its experimental drug to treat an organ-damaging hereditary disorder showed promise in an early-stage trial by suppressing the protein that causes the disease.
The drug aims to treat transthyretin-mediated amyloidosis (ATTR), a disease caused by mutations in the transthyretin (TTR) gene.
The company said the results of the trial were highly significant and that the administration of the drug, ALN-TTR02, reduced serum TTR protein levels by up to 94 percent.
"Suppression of TTR, the disease-causing protein in ATTR, was found to be rapid, dose-dependent, durable, and specific after just a single dose," Alnylam said in a statement.
Alnylam also said there were no serious adverse events or discontinuations in the study. The main goal of the study was to evaluate the safety and tolerability of a single dose of the drug.
"With orphan drug pricing, we forecast blockbuster global sales of $2 billion by 2020," Piper Jaffray analyst Edward Tenthoff, who has an "overweight" rating on Alnylam's stock, said in a note to clients.
The drug has an orphan drug status -- granted to drugs treating fewer than 200,000 patients -- that gives it seven years of marketing exclusivity from its approval date.
Analyst Tenthoff, who raised the price target on Alnylam shares to $20 from $17, expects the company to begin pivotal studies in 2013 and potentially gain marketing approval for the drug in 2015.
The company has already begun a mid-stage study and expects to enroll about 20 ATTR patients.
The new study will evaluate the reduction in TTR levels for a period of 208 days, as opposed to 56 days in the (early study), Rodman & Renshaw analyst Michael King said in a note.
Analyst King reiterated his "market outperform" rating on Alnylam and maintained his price target of $19 on the stock.
The company's shares rose as much as 51 percent to a two-year-high of $18.89, making them the top percentage gainers on the Nasdaq on Monday.
More than 6 million shares changed hands by mid afternoon, more than 26 times the stock's 10-day average moving volumes.
Alnylam develops drugs based on RNA interference, or RNAi -- a mechanism of silencing or turning on genes to prevent formation of proteins that can cause diseases.
Reporting by Balaji Sridharan in Bangalore; Editing by Don Sebastian, Roshni Menon