UPDATED: Merck's PhIII Tredaptive trial flops as another cholesterol drug flunks out

Merck's ($MRK) late-stage development effort suffered a major setback today as investigators announced that its huge Phase III trial of the "good" cholesterol drug Tredaptive--extended-release niacin/laropiprant--flunked its primary endpoint. Merck had enrolled more than 25,000 patients with a high risk for cardio events in the study but found no significant reduction in the risk of coronary deaths, nonfatal heart attacks, strokes or revascularizations compared with statin therapy. 

What investigators did find was a troubling spike in "the incidence of some types of non-fatal serious adverse events in the group that received extended-release niacin/laropiprant." But Merck didn't spell out what those serious adverse events were.

The company's shares slid more than 3% on the news as investors pondered Merck's prospects while generic competition eats away at its top line. It's also likely to raise fresh questions for company executives, who have defended their $8 billion-plus annual R&D budget while insisting they can gain approvals on blockbuster therapies.

Merck had set up the study, following patients for close to four years, in an ambitious effort to gain FDA approval. As it stands, Tredaptive was already approved in 70 countries but only garnered minor sales. Now Merck says that it will advise doctors not to start any patients on the drug and won't pursue U.S. approval, essentially killing one of the most expensive drug programs in the world. 

Merck's setback immediately triggered more chatter about the poor prospects of drugs that raise good cholesterol--a field that has inspired billions of dollars in deals and research programs. Roche killed dalcetrapib earlier this year, long after Pfizer ($PFE) scuttled its program after a study demonstrated that more patients taking its drug, torcetrapib, died. And Abbott ($ABT) didn't help after highlighting unimpressive data for its own good cholesterol therapy. 

Just weeks ago Eli Lilly ($LLY) and Merck investigators were pooh-poohing the earlier failures, saying they were weak contenders in the field of CETP inhibitors. Now Lilly--which ends 2012 under a cloud of clinical trial failures--will have to carry that fight on with evacetrapib while Merck keeps its fingers crossed with anacetrapib. 

The Phase III failure leaves Merck with only a handful of late-stage drugs, including the sleep drug Suvorexant, which faces a cloudy future in a crowded market, and odanacatib for osteoporosis. It also adds to the long list of failed efforts to find a drug that raised good cholesterol in a way that would protect patients from the threat of cardiovascular events.

"While we are disappointed in these results, we thank the investigators who have conducted the study and the patients who have participated in it," said Peter S. Kim, Ph.D., president, Merck Research Laboratories. "We are committed to working closely with the independent research team at Oxford University and with regulatory agencies to understand the results and determine next steps."

The news of the failure won't surprise many people at the FDA, which rejected the drug back in 2008.

- here's the press release

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