A closely watched study of Vytorin, a cholesterol drug marketed by drugmakers Merckand Schering-Plough, has uncovered a potential cancer risk, and failed to meet the main goal of improving cardiovascular health in patients with aortic disease.
However, the cancer risk, while disturbing, is not yet conclusive based upon the sample size of the study, which is known as the SEAS trial.
The American Heart Associate President-Elect Clyde Yancy said Monday that the latest data on cancer deaths is "an errant signal for now."
"We need to stay watchful. Certainly the signal was not strong enough that it should warrant a change in behavior," he said.
The shares of both companies fell after the data were released, with Schering off more than 15 percent and Merck down by 7 percent.
No significant difference was seen between the patients who received Vytorin and those who received a placebo in the study, according to data presented in London Monday by its its primary researcher Dr. Terje Pedersen of Ulleval University Hospital in Oslo, Norway.
The study did uncover slightly more cancer deaths in the drug group - 39 versus 23 in the placebo group. However, the researcher said this could be the result of chance.
To date, larger studies of Vytorin have not showed any elevated cancer risk associated with the drug.
The primary goal of the study was to identify whether patients with an irregular thickening of the main valve to the aorta would seen an improvement while taking the drug.
A secondary goal was to see if Vytorin would do better than a placebo in reducing atherosclerotic events, and here the drug did fare better than the placebo, researchers said. Atherosclerotic events include non-fatal heart attacks, the need for coronary artery bypass surgery or artery-clearing procedures, and chest pain and strokes.
But the drug was no better than the placebo on the other measure of cutting aortic valve disease events such as the need for valve replacement and cardiovascular death.
The combination of compounds in Vytorin also was found to have reduced patients' LDL cholesterol levels - the so-called bad cholesterol - by an average of 61 percent.
Merck and Schering-Plough were scheduled to release their financial results before the market's opening on Monday, but took the unusual step of postponing their earnings release until after the results of the SEAS trial were released.
"The study has given a clear-cut answer whether lipid lowering will influence the cause of aortic stenosis and we can conclude it does not," Pedersen said. But he added, that there are some benefits in reducing the risk of coronary artery disease in the study.
-Reuters contributed to this story.