Clinical Trial Involving HDL-Raising Drug Halted

Pfizer has halted its Phase 3 torcetrapib/atorvastatin clinical trial program after an independent data safety monitoring board determined that patients taking the drug combination were at an increased risk of dying compared with those taking only atorvastatin. The company also has announced it is ending its development program for torcetrapib.

Dubbed the Illuminate study, the investigation involved combining torcetrapib with atorvastatin, which is marketed as Lipitor and is Pfizer's headliner statin. Researchers thought the combination would be the next breakthrough medication for managing patients with heart disease by increasing HDL levels while also lowering LDL levels.

The international, multicenter trial, which involved 15,000 patients at high risk for heart attack and stroke, compared outcomes for people taking torcetrapib alone with those taking both torcetrapib and Lipitor. Patients receiving the combination had a higher mortality rate than did patients in the trial who were taking only atorvastatin. The company emphasized in its announcement that Lipitor was not considered an element in the increased risk of death.

"It is important to note that in the Illuminate trial, Lipitor was used as a comparator for safety and efficacy," says a Dec. 2 statement from Pfizer. "The only reason the study was stopped early was due to the torcetrapib data. The Illuminate Steering Committee wants to reassure physicians and patients that nothing in today's information has any impact on the safety or efficacy of Lipitor whatsoever," says Philip Barter, M.D., Ph.D., director of the Heart Research Institute in Sydney, Australia, and chair of the Illuminate trial's steering committee, in the statement.

Although initial studies indicated torcetrapib effectively raised HDL, the drug appeared also to slightly raise systolic blood pressure. Pfizer officials told the Washington Post they would comb through their research data to determine what had caused the heightened risk, but said that data gathered to date had not indicated blood pressure issues were related to an increased risk of death.