New research boosts hope that a highly anticipated, experimental class of cholesterol drugs can greatly lower the risk for heart attacks, death and other heart-related problems.
People taking one of these drugs had half the risk of dying or suffering a heart problem compared to others who were given usual care — typically one of the statin drugs such as Lipitor or Zocor, doctors found. Many people cannot tolerate statins or get enough help from them, so new medicines are being studied.
The results are "really impressive and very encouraging" for the new drugs, said one independent expert, Dr. Judith Hochman of NYU Langone Medical Center.
The studies were published online Sunday by the New England Journal of Medicine and discussed at an American College of Cardiology conference in San Diego last weekend.
They are fresh analyses from older studies designed to look at how much the drugs lower cholesterol, so they can only suggest that the drugs also lower heart problems, not prove that point. Definitive studies will take at least two more years, so the federal Food and Drug Administration will be deciding the drugs' fates with only results like this in hand.
Protein block helps clear LDL
The drugs have been found to lower LDL(low-density lipoprotein) or bad cholesterol more powerfully and in a different way than existing drugs, by blocking the protein PCSK9, a substance that interferes with the liver's ability to remove cholesterol from the blood.
The drugs are evolocumab, which Amgen Inc. wants to call Repatha, and alirocumab, which Regeneron Pharmaceuticals Inc. and Sanofi SA have named Praluent. Pfizer is also developing an anti-PCSK9 antibody, but the other companies are farther along in clinical trials on very similar protein-blocking agents.
Amgen Canada Inc. says its drug, or antibody, is designed to bind to PCSK9 and inhibit it from binding to LDL receptors on the liver surface. In the absence of PCSK9, there are more LDL receptors on the surface of the liver to aid in the removal of LDL-C (cholesterol).
Elevated LDL-C is recognized as a risk factor for cardiovascular disease.
Quest began with Canadian discovery
Dr. Jacques Genest, a researcher in cardiovascular diseases at McGill University said a Canadian discovery sparked much wider studies.
He said Dr. Nabil Seidah at the Clinical Resarch Institute of Montreal found a family that had a "protein overwork" of PCSK9, which causes "very high cholesterol."
Seidah and other researchers set out to find agents that could block the protein, knowing that people whose PCSK9 doesn't work well can have markedly decreased cholesterol and lifelong protection against heart disease.
Genest said researchers have already found a "tremendous level of efficacy" with evolocumab's use in nearly 4,500 patients in Phase 2 and 3 studies. He said outcome trials investigating the safety of these new drugs, involving 25,000 patients, should be completed in two or three years.
"The safety data, at least on the first several thousand patients exposed over one or two years, show the side effects very comparable to a placebo," Genest told CBC News.
Sharp drop reported in LDL
"Second, they are extremely efficacious, lowering cholesterol more than statins, by 50 to 70 per cent," he added.
The U.S. government will decide this summer whether to allow two of these drugs on the market.
Amgen Canada Inc. says Health Canada has not yet indicated whether it will approve its drug for the Canadian market. The company says five ongoing studies in the Phase 3 program will provide long-term safety and efficacy data.
Some doctors say side effects remain a question, especially on thinking, confusion and memory — problems the FDA has already voiced concern about and asked the companies to track.
The problems affected only 1 or 2 per cent of patients and may be temporary, but they were twice as common among people taking one of the new drugs and need to be closely monitored as studies continue, said Dr. Anthony DeMaria, a University of California at San Diego heart specialist and past president of the American College of Cardiology. As a patient facing potential side effects, "the last one I want" is one that affects the brain, he said.
Dr. Eric Topol, a cardiologist at Scripps Clinic in La Jolla, California, said the new results show "an unquestionable signal" of a potential safety issue. More side effects typically turn up once a drug is approved and used in a wider population, he said.
Most rigorous tests to come
Two other heart experts — Drs. Neil Stone and Daniel Lloyd-Jones of Northwestern University in Chicago — wrote in the medical journal that "it would be premature to endorse these drugs for widespread use" until the definitive studies are done in a couple of years. Other drugs that initially seemed good failed when put to the most rigorous test, they wrote.
Still, the results so far suggest that the drugs "appear to be on track" to be important new medicines, they wrote.
Dr. Clyde Yancy, cardiology chief at Northwestern University in Chicago and a former American Heart Association president, agreed.
"Science has revealed a brand new approach to treating cholesterol," and there is "reasonable enthusiasm" it will be a big boon to patients, he said.
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