Injectable therapy shows promise in global trial but more study needed, researchers say
By Dennis Thompson
TUESDAY, May 13, 2014 (HealthDay News) -- A new injectable drug can further knock down cholesterol levels in people who take cholesterol-busting statin medications, according to the results of a global trial.
People taking the new therapy alongside statins enjoyed a 63 percent to 75 percent decrease in their "bad" (LDL) cholesterol levels, on top of the reduction caused by the traditional statin medications, researchers reported. The findings are published in the May 14 issue of the Journal of the American Medical Association.
"This drug enhances the body's natural way of reducing LDL levels in the bloodstream," said lead author Dr. Jennifer Robinson, a professor of epidemiology and cardiology at the University of Iowa College of Public Health. "It lets us get cholesterol really well-treated in people with genetic cholesterol disorders or people who can't take large amounts of statins."
Evolocumab is a so-called "human monoclonal antibody" that, in a roundabout way, improves the body's ability to remove cholesterol from the bloodstream.
Cells primarily located in the liver contain receptors that target LDL cholesterol and remove it from the bloodstream. But the liver also produces a regulatory protein called PCSK9 that binds to and breaks down these receptors, Robinson said.
The antibodies in evolocumab are designed to intercept PCSK9, preventing the protein from breaking down the cells' LDL receptors, which allows them to stay in circulation longer to remove LDL cholesterol, she explained.
The phase 3 clinical trial was funded by the drug's maker, Amgen, and conducted at 198 sites in 17 countries. Over the course of 12 weeks, just over 2,000 people taking moderate to high doses of statins were randomly assigned to also take evolocumab, or another cholesterol-lowering drug called ezetimibe (Zetia), or an inactive placebo.
Compared with the placebo, evolocumab taken every two weeks reduced LDL cholesterol levels an additional 66 percent to 75 percent, and taken monthly cut the level by 63 percent to 75 percent. By comparison, ezetimibe provided an additional cholesterol reduction of up to 24 percent, the investigators found.
According to the findings, evolocumab had adverse events and side effects comparable to those experienced by people taking either statins or ezetimibe. "Because it's a very specific antibody, it seems to be very well-tolerated without any drug interactions or any side effects," Robinson said.
Evolocumab will be mostly helpful in treating people with a genetic disorder that causes them to have high cholesterol, Robinson said. About 1 in 500 people have this disorder, according to the U.S. National Institutes of Health.
It also could help people with high cholesterol who can't take large doses of statins, Robinson added, estimating that as many as 10 percent of people with heart disease or diabetes can't tolerate the recommended dose of statins.
However, a spokeswoman for the American Heart Association cautioned that the drug's impact on the risk of a heart attack or a stroke has not been tested yet.
Dr. Mary Ann Bauman, who is also medical director for Women's Health and Community Relations at INTEGRIS Health in Oklahoma City, said, "I do think that this study did what it was supposed to do . . . to show it was safe, reasonably well-tolerated and did have an effect on LDL cholesterol."
But, she added, "The real question will be whether decreasing cholesterol levels with this medication makes a difference in cardiovascular events."
Statins have been proven to prevent heart attacks and strokes, but Bauman noted that clinical trials of ezetimibe have had mixed results. The drug lowers cholesterol, but does not necessarily prevent heart attacks.
Robinson said a follow-up study is underway to evaluate the drug's longer-term outcomes and safety. But if it does gain U.S. Food and Drug Administration approval, she noted, the drug will be expensive. Similar antibody drugs already are used to treat arthritis patients, and those can cost patients thousands of dollars a year.
"It's not going to be for everybody, but it's going to be very important for certain people," those with genetic cholesterol disorders and those who can't take large doses of statins, Robinson added.
For more about statins, visit the U.S. National Library of Medicine.
SOURCES: Jennifer Robinson, M.D., M.P.H., professor of epidemiology and cardiology, University of Iowa College of Public Health; Mary Ann Bauman, M.D., medical director, Women's Health and Community Relations, INTEGRIS Health Inc., Oklahoma City, and spokeswoman, American Heart Association; May 14, 2014, Journal of the American Medical Association
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