IS IT really possible to melt away the fat that gradually clogs up our arteries? That鈥檚 the claim that hit the headlines last week. But experts are treating the reports with caution.
In a study published last week, 47 people with heart disease were given five weekly injections of an experimental drug known as ETC-216. Other patients were injected with a placebo of salty water. At the end of the trial, the size of the fatty plaques clogging the arteries of the patients given ETC-216 had been reduced by an average of 4 per cent, reported Steven Nissen, the cardiologist at the Cleveland Clinic Foundation in Ohio who led the study. 鈥淣o other drug has ever produced anywhere near this effect even when it has been used for years,鈥� he says. 鈥淚t鈥檚 mind-blowing.鈥�
ETC-216 is a kind of high density lipoprotein, or HDL, known as 鈥済ood cholesterol鈥� because it carries other cholesterols and fats away from arteries. Researchers have long been keen to test the effects of boosting HDL levels in the blood. Some drugs that drive up HDL levels are now being tested, but their effectiveness has yet to be proven.
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An alternative would be to try injecting HDL directly into the blood. But no one has ever funded such a study. Companies are not interested because the idea is in the public domain and therefore cannot be patented.
That鈥檚 where a rare form of HDL found in 40 northern Italian villagers comes in. Two decades ago, it was reported that villagers with the ApoA-I Milano form of HDL live long and have low rates of cardiovascular disease, despite extremely low blood levels of HDL. The sequence of the major protein within their HDL was patented, and is now licensed to the Michigan-based company Esperion Therapeutics.
The company asked Nissen to test a genetically engineered form of this 鈥渟uper HDL鈥�, using the technique he developed for measuring the size of plaques in arteries with an intravenous ultrasound camera. His study (Journal of the American Medical Association, vol 290, p 2292) is the first reported success for any HDL therapy.
鈥淭he results of this study are surprising to even the most optimistic supporters of the concept,鈥� writes Daniel Radar of the University of Pennsylvania School of Medicine in an editorial accompanying the results.
However, the study has several limitations, such as the small number of patients examined. And while researchers agree that reducing the size of plaques should improve patients鈥� health and help them live longer, Nissen measured their size in only one location and only for a short time. He says a larger trial will address some of these issues.
But even before his study began, the whole argument for using 鈥渟uper HDL鈥� had been undermined. Follow-up studies of the Italian villagers have shown that they do not really live any longer or suffer less heart disease. That means that if ETC-216 really does work, injections of normal HDL might work just as well if not better. 鈥淚 doubt we鈥檒l ever know,鈥� says Nissen. 鈥淣o one is going to pay for a trial to test common HDL, because there鈥檚 no commercial potential.鈥�