Pfizer Inc. (PFE) halted development of a drug to boost good cholesterol that was the most important medicine in its pipeline, after more patients than expected died during a large clinical test.
The unanticipated excess of deaths, whose number was small but wasn't specified by the company, became known Saturday after a board of independent experts reviewed the latest data from a 15,000-patient test of the drug called torcetrapib.
Citing patient safety, Pfizer said in a statement that it is terminating all clinical tests of torcetrapib and its plans to bring the drug to market.
The failure of torcetrapib is a heavy blow to Pfizer, the world's largest drug maker by sales. The company had bet on torcetrapib to take the place of cholesterol-fighter Lipitor, the company's best-selling product with $12.19 billion in revenue last year. Lipitor could lose patent protection as soon as 2010.
Doctors and investors have been watching torcetrapib closely because it seemed able to profoundly raise the type of cholesterol - called HDL - that could help keep arteries clear.
But torcetrapib has been dogged by safety worries. The medicine showed a tendency to raise blood pressure as it also raised good cholesterol.
Still, the increase in deaths for the patients who received torcetrapib was a shock. "We were very surprised ," said Philip Barter, director of the Heart Research Institute in Australia and chairman of the committee overseeing the large study, in the Pfizer statement. "We believed that the study was coming along as expected," he said.
Dr. Steven Nissen, chairmain of cardiovascular medicines at the Cleveland Clinic, called the setback "terribly disappointing." Nissen is the leader of another clinical test of torcetrapib to see if the medicine reversed the plaques that clog arteries feeding the heart. He said that finding new drugs to raise HDL safely and effectively remains an important goal. "We still don't know if this is a problem specific to torcertrapib or this approach to raising HDL isn't going to work."
The test that detected the more serious problems was a 15,000-patient study that was supposed to continue until 2009 or early 2010. Half the patients received tocetrapib plus Lipitor. The other half got Lipitor alone. Pfizer said the study cast no doubt on the safety and effectiveness of Lipitor.
Some analysts thought that the blood pressure problems that were already known would doom torcetrapib. Other companies, including Merck & Co. (MRK) and Roche Holding AG (RHHBY), were working on alternatives to torcetrapib that don't appear to increase blood pressure.
Only last Thursday Pfizer management had affirmed confidence in torcetrapib at a meeting with analysts to review the company's pipeline. The company affirmed its plan to seek Food and Drug Administration approval of torcetrapib taken in combination with Lipitor in the second half of 2007.
During the meeting, Pfizer research president John LaMattina said, "We believe this is the most important new development in cardiovascular medicine in years."
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