Independent trial monitors have crunched data from a massive 30,000 patient cholesterol trial underway at Merck & Co. (NYSE:MRK) and have recommended that the trial continue as planned.

The fact that independent monitors evaluated efficacy and safety data to consider the likelihood of futility in this trial and still came away supporting its continuation is in itself a big win for Merck because similar programs at competitors have been shuttered.

Image source: Merck & Co.

Tapping into a massive market
Despite the widespread use of cholesterol-lowering statins, more than 600,000 Americans die every year because of heart disease, and without additional treatment options, that number could climb given estimates that as many as 76 million Americans suffer from high cholesterol levels.

While high cholesterol isn't the only cause of heart disease, it is considered to be a major contributor.

Cholesterol itself isn't the problem. In fact, cholesterol is essential to healthy cell formation. However, in patients with too much bad cholesterol, or LDL cholesterol, deposits can build up in the arteries that cause heart attack or stroke.

Because of this, statins that lower cholesterol production in the liver have been used since the 1980s to lower bad cholesterol levels.

Statins have become so relied upon in the battle to prevent heart disease that they're used in tens of millions of patients every day, making them the most widely prescribed medicines in America.

Although there are many statins that are used to treat patients, the most widely used is generic atorvastatin, which was sold by Pfizer (NYSE:PFE) as Lipitor prior to losing patent protection in 2011.

At its height, Lipitor was so wildly successful that it generated more than $13 billion in annual sales for Pfizer, making it the top-selling medicine on the planet, and over Lipitor's entire life cycle, Pfizer recorded over $130 million in Lipitor sales, which makes it the best-selling drug of all time.

Stumbling toward a new class of drugs
Recognizing that the statin market is massive and that it would be tough to replace revenue lost when statin patents expire, various drugmakers, including Pfizer, Eli Lilly (NYSE:LLY), and Merck, spent hundreds of millions of dollars developing next-generation cholesterol fighters that work in entirely new ways.

Among the most promising of these next-generation drugs were cholesterol esterase transfer protein, or CETP, inhibitors. This class of drugs sought to lower LDL levels, and boost good cholesterol, or HDL, levels, by interrupting a key transfer that occurs between LDL and HDL.

In early-stage trials, CETP inhibitors put up promising results, but their track record in late-stage trials has been downright dismal.

For example, Pfizer was one of the first companies to usher its CETP drug into phase 3 studies, but once independent monitors discovered that patients taking Pfizer's drug were more at risk of death and cardiovascular events than expected, it was forced to shutter that program entirely.

Pfizer's disappointment was followed a few years later by a similar failure at Roche. In 2012, independent monitors put a stop to the development of its CETP inhibitor after an interim review determined that there was no way that the trial could achieve efficacy results that would support a filing for approval.

Most recently, Eli Lilly was forced to shelve its CETP candidate too in October when independent monitors determined that its drug was also ineffective.

Given that monitors have put an early end to the CETP programs of Pfizer, Roche, and Eli Lilly, the decision to allow Merck's to continue is almost remarkable, but investors may not want to get too excited about this development.

After all, Eli Lilly's trial was extended earlier this year and yet it still failed to achieve its endpoint and Merck's trial isn't expected to wrap up until 2017, so there's still plenty of time for things to go wrong.

Looking ahead
The price tag of Merck's CETP program is likely to be about half a billion dollars, so the company would really like to see these phase 3 trials pan out.

If it does, then Merck would face little competition in the CETP space, which, given the size of the cholesterol drug market, could make this a very profit-friendly medicine.

However, CETP inhibitors disappointing track record make me unwilling to bet that Merck's drug will succeed, and for that reason, it's probably best to base any decision to invest in Merck on other opportunities and risks, rather than the CETP program. 

 

Todd Campbell has no position in any stocks mentioned. Todd owns E.B. Capital Markets, LLC. E.B. Capital's clients may have positions in the companies mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.