New cholesterol-lowering drug could halve risk of heart attack, stroke

Currently, statin therapy is the standard treatment for many patients with high cholesterol. But a new study published in The New England Journal of Medicine claims a drug called evolocumab could be much more effective; it reduced cholesterol levels so dramatically that patients' risk of cardiovascular events - such as heart attack and stroke - fell by more than half, compared with those receiving standard therapy alone.

Around 71 million people in the US have high LDL cholesterol, putting them at increased risk of cardiovascular diseases.

Researchers at Brigham and Women's Hospital in Boston, MA recently presented their findings at the American College of Cardiology's 64th Annual Scientific Session in San Diego, CA.

The study was a 1-year extension of 12 phase 2 and 3 clinical trials that had assessed evolocumab's ability to reduce levels of low-density lipoprotein (LDL) cholesterol - commonly referred to as "bad" cholesterol because of the role it plays in blocking the arteries

According to the Centers for Disease Control and Prevention (CDC), around 71 million Americans have high LDL cholesterol - blood levels at 160 milligrams per deciliter (mg/dL) or higher. High LDL cholesterol can raise the risk of heart attack, stroke and heart disease.

The 4,465 patients involved in the study had been a part of at least one of the previous trials investigating evolocumab, which works by blocking a protein that stops the liver from removing LDL cholesterol from the blood - called proprotein convertase subtilisin-kexin 9 (PCSK9).

Of the participants, 2,976 were randomized to receive an injection of evolocumab under the skin every 2 or 4 weeks plus standard therapy, while 1,489 patients received standard therapy alone, which mostly involved moderate- or high-intensity statin therapy. The average follow-up duration was 11.1 months.

The study was open-label, meaning the participants were fully aware of the treatment they were receiving, as were the researchers. However, a central committee that reviewed the data - assessing the effects of evolocumab on LDL cholesterol levels and reporting any cardiovascular events during follow-up - was blinded to the treatment groups.

Evolocumab linked to 53% reduction in cardiovascular events

At study baseline, the average LDL cholesterol level among participants was 120 mg/dL, which the researchers say is similar to the average level found among the general population.

However, the team found that patients treated with evolocumab experienced an average 61% reduction in LDL cholesterol levels. Within 12 weeks, LDL cholesterol levels reduced to less than 100 mg/dL - defined as the optimal range - in 90.2% of evolocumab-treated patients, while levels reached 70 mg/dL or less for 73.6% of patients who received the drug. These reductions were sustained throughout the entire follow-up period, the researchers report.

In comparison, only 26% of patients who received standard therapy alone saw their LDL cholesterol levels fall below 100 mg/dL, while only 3.8% had such levels fall below 70 mg/dL.

What is more, compared with patients who received standard therapy alone, those treated with evolocumab experienced a 53% reduction in cardiovascular events, including heart attack, stroke, hospitalization, angioplasty and death; evolocumab-treated patients had a 0.95% risk of a cardiovascular event during follow-up, while standard-therapy patients had a 2.18% risk.

The research team says these results remained even after accounting for patients' age, baseline LDL levels, statin use, primary or secondary prevention and incidence of valve disease. Evolocumab was also found to be well tolerated by patients.

However, the researchers admit their study is subject to some limitations. They note, for example, that the number of cardiovascular events in the study was relatively small, with only 60 identified.

Still, the research team believes the findings show that not only is evolocumab effective for dramatically reducing cholesterol levels, but it may be effective for rapid risk reduction of cardiovascular events. 

"The reduction in LDL was profound and that may be why we saw a marked reduction in cardiovascular events so quickly. It suggests that if we can drive a patient's LDL cholesterol down a large amount to a very low level, we may start to see a benefit sooner than would be expected with a more modest intervention."

The researchers note that because evolocumab works differently to statins - which block an enzyme in the liver that is responsible for making cholesterol - the drug also holds hope for patients who do not respond to statins or who are unable to tolerate them.

Evolocumab is currently undergoing further testing in a clinical trial involving more than 27,500 patients, the results of which are expected in 2017. Though there is no definitive conclusions about evolocumab's effectiveness can be made until then, this current study shows promise.

We know from previous research that evolocumab lowers LDL cholesterol, but these data offer support for their potential to reduce major adverse cardiovascular events in our patients.

The study was funded by Amgen - the biopharmaceutical company that manufactures evolocumab.

In January, another team of researchers reported on a study that identified a more natural way to reduce LDL cholesterol: avocados. Published in the Journal of the American Heart Association, the study revealed that eating one avocado a day as part of a moderate-fat diet reduced LDL cholesterol levels by 13.5 mg/dL for participants who were overweight or obese.

References:

1.  Efficacy and safety of evolocumab in reducing lipids and cardiovascular events, Marc Sabatine, et al., N EngJ Med, doi: 10.1056/NEJMoa1500858, published online 15 March 2015.
2.  American College of Cardiology news release, accessed 16 March 2015.
3.  Additional source: CDC, Cholesterol facts, accessed 16 March 2015.