Heart experts clash on Vytorin and cancer risk

MUNICH (Reuters) - Experts clashed on Tuesday over the safety of Merck & Co and Schering-Plough Corp's cholesterol drug Vytorin as full results from a controversial study were presented at Europe's biggest medical congress.

Researchers involved in the so-called SEAS study -- highlights of which were first released in July -- said there was no credible evidence linking Vytorin to cancer and that the higher number of cases seen in the trial was simply a fluke.

But an editorial in the influential New England Medical Journal, which published the full data from the Vytorin study online, said the safety of the drug was now in doubt, and several leading doctors also expressed concerns.

The full report on the trial, involving 1,873 patients, showed a total of 105 cancer cases among Vytorin patients compared with 70 taking a placebo. That was an upward revision from the totals of 93 and 65 reported in July.

Lead investigator Terje Pedersen of Ulleval University Hospital in Oslo, however, said cross-checks with cancer rates in two much larger, ongoing trials simply did not support the idea that Vytorin was linked to cancer.

Other leading cardiologists were not so sure.

"I am quite concerned," Heinz Drexel, professor of medicine at Austria's University of Innsbruck, told Reuters.

"At the moment, I would not take ezetimibe myself," Drexel said, although he urged patients not to stop treatment without consulting their doctor.

Ezetimibe is one of the two ingredients in Vytorin, alongside established statin drug simvastatin.

Pedersen presented data on the drug at the annual European Society of Cardiology congress in Munich. His trial had aimed to see whether Vytorin could help prevent heart valve problems but concluded it was no better than a placebo, or dummy, pill.

U.S. lawmakers have already announced a probe into the possible Vytorin cancer link, and shares in both the drug's makers have fallen since July. The U.S. Food and Drug Administration expects to give its verdict in about nine months.

On Tuesday, two U.S. congressmen released a letter asking Merck and Schering-Plough for more information about a report the companies submitted to regulators assessing the possible link between Vytorin and cancer.

The companies said in a statement they would cooperate with the request.

Merck shares closed 2.4 percent lower on the New York Stock Exchange, while Schering-Plough shares dropped 1.6 percent.

UNCERTAINTY

The key for the firms -- both of which say the finding is simply a statistical anomaly -- will be doctors' reaction to the furor.

The New England Journal of Medicine added to the skepticism.

"Physicians and patients are unfortunately left for now with uncertainty about the efficacy and safety of the drug," it said in an editorial.

It noted that ezetimibe interfered with gastrointestinal absorption not only of cholesterol but also other molecules that could conceivably affect the growth of cancer cells.

Pedersen said there was absolutely no evidence for such a cancer-causing mechanism -- echoing the conclusions of Richard Peto, a cancer epidemiologist at Oxford University.

Credit Suisse industry analyst Catherine Arnold said renewed attention on the cancer issue could cause weakness in both drugmakers' shares but the latest news should not materially change the outlook for their cholesterol business.

Douglas Weaver, president of the American College of Cardiology (ACC), said he was more than 90 percent certain the association between Vytorin and cancer was chance.

But Timothy Gardner, president of the American Heart Association (AHA), was more cautious. "We need to be very careful and watch this. We are not able to definitively say that there is no risk here with this drug," he told reporters.

The AHA issued a statement on Tuesday reiterating that Vytorin should not be used as a first-line treatment but only when patients failed to respond to top doses of statins.

Both the AHA and ACC said patients should not stop taking any medications without first talking to their doctor.

Vytorin is used much more rarely in Europe than in the United States, where doctors say past high prescription rates suggest it is not always reserved for those failing on statins.

Vytorin sales have been hit hard this year, initially by trial results in January showing it was no more effective than simvastatin alone in reducing plaque in neck arteries.

(Editing by Rory Channing/Quentin Bryar/Braden Reddall)