Pfizer Inc., the world's largest pharmaceutical company, suffered a severe blow this weekend when it terminated clinical trials of a touted cholesterol drug after a high number of patient deaths.
The decision to stop all clinical trials of torcetrapib also cast doubt on what medical experts had hoped would be a great advance in the treatment of heart disease.
"I am very disappointed," said Dr. Steven Nissen, chairman of cardiovascular medicine at the Cleveland Clinic in Ohio and chief medical investigator in Pfizer's trials, which were halted Saturday. "We had high hopes for this drug."
Investment analysts warned that Pfizer would have to expand its cost-cutting program and accelerate other projects to buttress its shares, which are likely to drop today as investors cool to the company's prospects.
Cholesterol drugs and other treatments that lower the risk of cardiovascular disease account for the largest share of pharmaceutical sales in the U.S. and worldwide.
But many of the current drugs, including Pfizer's category-leading Lipitor, are losing or expected to lose their patents by the end of the decade and encounter competition from cheaper generic versions.
New York-based Pfizer had hoped to create a new class of cholesterol drugs by combining its existing medicine, which reduces low-density, or "bad," cholesterol, with torcetrapib, which raises the level of high-density, or "good," cholesterol.
Good cholesterol is believed to help decrease the buildup of plaque in the arteries that causes cardiovascular disease.
Trial patients who had taken the combined drug died in higher numbers than those taking only Lipitor, the company said.
More than 15,000 patients worldwide had participated in the testing that began last year, about half of them in the United States.
All the participants were at high risk of heart attack and stroke. Since the testing began, 82 people who had been taking the new drug died, compared with 51 of those taking only Lipitor, Pfizer said.
Those taking torcetrapib also had more cardiovascular complications, such as higher blood pressure.
The reasons for the complications and deaths won't be known for months, Nissen said. "We don't know if this is unique to torcetrapib or if [final findings] will suggest that the entire approach does not work."
Other pharmaceutical companies such as Roche Holding and Merck & Co. reportedly are testing products that increase good cholesterol.
Roche representatives could not be reached Sunday. A Merck spokesman said the company does not comment on products in development until trials are completed.
Pfizer invested nearly $1 billion in torcetrapib, anticipating the expiration of Lipitor's patent by 2010. Lipitor has annual sales of more than $12 billion and represents nearly a fifth of the company's revenue.