Source: Esperion Therapeutics,

The U.S. Food and Drug Administration approved the first cholesterol-busting statin drug more than 20 years ago, and statins' proven ability to cut cholesterol levels has turned them into the most widely used drugs in America. However, for millions of people statin therapy alone fails, and that's why Esperion Therapeutics (ESPR 1.63%) is developing ETC-1002, a clinical-stage cholesterol fighter that just put up impressive results in midstage studies.

First, a bit of background
Despite tens of millions of Americans taking statins such as Pfizer's (PFE -0.12%) Lipitor every year, heart disease remains the No. 1 cause of death in the United States. Unfortunately, that isn't likely to change anytime soon given that roughly half of all Americans have at least one of the major risk factors that can result in heart disease.

One of the most common of these risk factors is high levels of LDL cholesterol, also known as "bad" cholesterol.

Cholesterol is produced in the liver and used by the body to build new cells, insulate nerves, and create important hormones. Foods such as milk and meat also increase the body's cholesterol levels. Although cholesterol is necessary for the human body, high levels of cholesterol can clog up the arteries, restricting blood flow and potentially causing a heart attack or stroke.

To reduce the chances of that happening, doctors commonly prescribe statins that help reduce the liver's production of cholesterol by inhibiting the activity of the HMG-CoA reductase enzyme. By reducing cholesterol production, statins also increase "bad" cholesterol receptors that help remove LDL from the bloodstream. The most commonly prescribed statin in the U.S. is the generic form of Lipitor, a drug so widely used that sales peaked at $12 billion annually before it lost patent protection.

Roger Newton, CSO of Esperion Therapeutics

Boosting effectiveness
At the wheel of Esperion Therapeutics' research is Lipitor's co-developer Roger Newton. As Esperion's founder and chief science officer, Newton is continuing his work by discovering new therapies that target other key cogs responsible for the body's cholesterol production.

The most advanced of these drugs is the aforementioned ETC-1002, which can be taken orally alongside statins. ETC-1002 limits the production of a substrate necessary to form cholesterol and helps the body synthesize more cholesterol.

During midstage clinical trials, bad cholesterol levels in patients who received ETC-1002 alongside standard-of-care statin therapies including Lipitor fell significantly more than levels in patients receiving statins alone.

Cholesterol levels in patients who took the 120 milligram dose of ETC-1002 fell by 17% from baseline, and that increased to 24% in those taking the 180 mg dose. That was significantly better than the placebo group, where bad cholesterol levels fell 4%.

Looking ahead
The midstage results were impressive and could indicate that Newton has captured lightning in a bottle yet again. However, investors should keep their enthusiasm in check given that this was a small midstage study. Esperion Therapeutics plans to launch a much larger phase 3 trial soon, and the results of that study could either back up or call into question these phase 2 findings. Regardless, ETC-1002's success so far -- and Newton's track record with Lipitor -- means this is one small-cap biotech company worthy of investors' attention.