Many patients – and probably some doctors – are scratching their heads over Vytorin. Though it has been on the market for four years, little is known about its safety and effectiveness. This year, two studies – ENHANCE and SEAS – have only added to the confusion over the cholesterol drug. Both concluded that Vytorin offered little added benefit when compared with cheaper drugs, while the latter indicated that the medication could be linked to cancer. Still, Merck & Schering-Plough are standing by their former blockbuster, hoping that larger clinical trials will vindicate it. Unfortunately for patients, those trials are years from completion.
Vytorin, which was developed and marketed jointly by Merck and Schering-Plough, was approved for use by the Food & Drug Administration (FDA) in 2004. Since it came on the market, Vytorin sales have reached $5 billion per year. Vytorin is a combination of cholesterol-lowering Zetia (ezetimibe) and the statin Zocor (simvastin). Statins like Zocor reduce the amount of cholesterol produced by the liver, while Zetia lessens the amount of cholesterol in food that is absorbed in the intestines. Theoretically, that should translate to fewer heart attacks, clogged arteries and the like, but there is no actual proof of that yet.
Questions over the safety and effectiveness of Vytorin were first raised in January, when the long-awaited ENHANCE study was finally released. ENHANCE showed Vytorin were ineffective in preventing clogged arteries, and might actually increase plaque in some users. Adding to the controversy was the fact that Merck and Schering-Plough delayed releasing ENHANCE for more than a year – something critics of the company have likened to fraud.
In March, the full ENHANCE study was vetted during the annual meeting of the American College of Cardiology (ACC). A panel of four doctors concluded that Vytorin should be used only as a last resort, considering that the expensive drug did not provide any added benefits. “Our strongest recommendation is that people need to go back to statins,” said panel member Dr. Harlan Krumhotz.
In July, Merck & Shearing-Plough released yet another Vytorin study, SEAS, which was designed to see if the drug helped people with aortic stenosis avoid heart attacks. Not only did SEAS show that Vytorin offered no additional heart attack prevention, but Vytorin patients enrolled in the study had higher rates of cancer than those taking a placebo. In the trial 102 patients taking Vytorin developed cancer, compared with 67 taking the placebo. Of those, 39 people taking Vytorin died from their cancer, compared with 23 taking placebo. Researchers conducting the study said that while those numbers don’t prove a definitive cancer link, they were “statistically significant, meaning the odds were less than 5 percent that they were the result of chance.
Merck and Schering-Plough called the cancer findings an anomaly. The companies based that claim on an analysis of the SEAS cancer findings that was conducted by Richard Peto, an Oxford University statistician. Peto pooled data from two much larger ongoing studies of Vytorin and said they showed that the cancer risk was a statistical fluke. He called the contention that Vytorin could cause cancer “bizarre”.
But last week, when SEAS was published in the New England Journal of Medicine, the editors of the journal also published a strongly worded editorial criticizing Peto’s findings. The authors of the editorial wrote that a link to cancer deaths “should not be assumed to be a chance finding until further data are in,”, adding that doctors and patients “are unfortunately left for now with uncertainty about the safety and efficacy of the drug.”
Thanks to ENHANCE and SEAS, Vytorin is now mired in confusion and controversy. Unfortunately, a clearer picture of the drug’s effectiveness and safety is not likely to emerge until 2012, when larger clinical trials are finally complete. That’s not much comfort for patients taking Vytorin now.
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