High-risk patients who took an experimental cholesterol drug for 78 weeks had “bad” cholesterol levels 60 percent lower than those in a control group. But the potential price tag has raised some eyebrows.

A new injectable drug designed to lower LDL, or “bad” cholesterol, showed its worth in a large study that released results this weekend.

The drug, evolocumab, dramatically reduced LDL and cut the risk of negative cardiac events, such as heart attack and stroke, by half when given alongside statins. Statins are the most commonly used cholesterol-lowering drugs.

In a study of almost 4,500 patients for a year, those taking the new drug saw their “bad” cholesterol levels drop 62 percent more than those in the control group.

At the start of the study, the average LDL cholesterol measure for volunteers was 120 mg/dL, which is close to the average level for Americans. The participants were all at high risk of negative cardiac events.

“The reduction in LDL was profound and that may be why we saw a marked reduction in cardiovascular events so quickly,” lead author Dr. Marc Sabatine, a senior physician in the Division of Cardiovascular Medicine at Brigham and Women’s Hospital in Boston, said in a press statement. “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.”

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LDL contributes to plaques, thick, hard deposits that can clog arteries and make them less flexible. Plaques can rupture, leading to fatal blood clots.

Evolocumab is a monoclonal antibody that blocks a protein, called proprotein convertase subtilisin-kexin 9 (PCSK9), that limits the liver’s ability to remove LDL cholesterol from the blood.

Previous studies had shown that evolocumab lowers LDL cholesterol numbers. But this longer-term work showed that those numbers are actually linked to a lower risk of heart attack, stroke, hospitalization, and death.

To enjoy lower risks over time, patients would have to take PCSK9 drugs continuously. If approved, the drugs would likely have an eye-popping price tag, similar to other new biologic drugs.

That potential price tag has some concerned about how the drugs would affect patients and the healthcare system as a whole.

“High cholesterol is one of the most prevalent conditions in the developed world and with primary prevention of high cholesterol as the eventual target for manufacturers, PCSK9 inhibitors will likely be the highest selling class of medications in history,” said Dr. William Shrank, chief scientific officer of CVS Health, in a press statement. “With a robust pipeline of expensive specialty drugs this is just the beginning, and the resilience and ability of our healthcare system to absorb such high costs will be tested if rigid cost control mechanisms are not put in place.”

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Guidelines put out in 2013 by the American College of Cardiology and the American Heart Association suggest that doctors wouldn’t and shouldn’t prescribe biologic cholesterol drugs to everyone who has high LDL cholesterol even after taking statins.

“The evidence-driven cholesterol guidelines did not endorse the concept that lower LDL cholesterol levels are better at all costs. They emphasized that, while lower is better, it matters how you get there and whether the benefits outweigh the risks for that patient,” Drs. Neil Stone and Donald M. Lloyd-Jones wrote in an editorial that accompanied the study results in the New England Journal of Medicine.

Stone and Lloyd-Jones are cardiologists at the Feinberg School of Medicine at Northwestern University.

Though no significant adverse side effects were highlighted in the new study, more research is needed to see how patients respond to evolocumab over the long-term.

There is already a long-term trial of evolocumab following 27,500 patients, but results aren’t expected until 2017.

“Much work remains to be done, but PCSK9 inhibitors appear on track to become important arrows in our quiver for targeting reduction of cardiovascular events among higher-risk patients when statins are not enough,” Stone and Lloyd-Jones concluded.

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