Why was the Niaspan vs. Zetia trial stopped?

Yes, folks, we have another cholesterol-drug trial mystery on our hands. A study comparing Abbott's Niaspan drug with Merck/Schering-Plough's Zetia was terminated by an independent steering committee. All we know at this point is what's posted on the NIH clinical trial registry: It wasn't stopped for safety reasons, but based on results of a "pre-specified, blinded interim analysis." The trial's lead investigator wouldn't tell Dow Jones any more about the trial's halt, and the companies themselves said they didn't know.

Obviously someone knows, but for some reason those people aren't talking. Presumably some people at Abbott and Merck/Schering-Plough know, too--just not the PR staff that's talking to the press. And the results could be significant; if one or another of the drugs proved clearly superior, scrips could grow by 5 percent to 20 percent over the next year, analyst Jon LeCroy told the news service. Or shrink by that much, depending.

So here's the skinny on the stopped trial, known as ARBITER 6 HALTS. Begun in November 2006, it tracked 400 patients at risk for heart attacks who were already taking statin meds. One group got Niaspan added to its regimen; the other, Zetia. Each drug takes a different tack on cholesterol, with Niaspan boosting "good" cholesterol and Zetia primarily lowering the "bad" sort. Researchers then looked at artery thickness to see how each drug fared, using the same ultrasound technique that proved so troublesome in the now-infamous Enhance study that compared Zocor/simvastatin with Vytorin, the Merck/Schering-Plough combo drug that mixes Zocor with Zetia.

Some analysts are speculating that Niaspan was the study victor. "We think Niaspan likely performed better than Zetia in the HALTS study," Wells Fargo analyst Larry Biegelsen told Bloomberg. "A positive result for Niaspan and Simcor in HALTS could represent upside potential to our Abbott estimates." But though LeCroy also suspected Niaspan worked better, he said he wouldn't rule out a Zetia victory, or a tie.

- get the scoop from Dow Jones
- read the Bloomberg piece