Questions Linger on Pfizer Drug

A new study of a cholesterol drug recently abandoned by Pfizer(PFE Quote) doesn't answer the question of why the compound failed or whether similar experimental drugs will be successful.

"The lack of efficacy may be related to the mechanism of this drug class or to molecule-specific adverse events," says the Pfizer-sponsored research that was unveiled at the annual meeting of the American College of Cardiology.

The drug is torcetrapib, which Pfizer had hoped would be the successor to Lipitor, the world's best-selling drug and a contributor of $12.9 billion, or 27%, of last year's corporate revenue.

But Pfizer canceled work on the drug in early December after the company said a clinical trial showed that patients receiving torcetrapib plus Lipitor had a higher-than-expected death rate than patients receiving Lipitor alone.

Pfizer executives were hard-pressed to explain what happened in the 15,000-patient test, whose full results won't be available until later this year. Monday's results of another clinical trial of nearly 1,200 patients only offered possible scenarios.

The latest research found that torcetrapib plus Lipitor failed to significantly reduce the buildup of artery-clogging plaque when compared with Lipitor alone. Patients were tested for 24 months.

As in the larger clinical trial, researchers found that torcetrapib raised patients' blood pressure, lowered so-called bad cholesterol and raised good cholesterol. The research was posted online by The New England Journal of Medicine, in advance of publication in its March 29 issue.