An experimental vaccine was found to keep cholesterol levels low in mice. Now phase I trials in humans are set to begin.

With heart disease the number one cause of death for men and women in the United States, the medical community has increasingly focused on how to lower cholesterol and reduce cardiac events like heart attacks.

While drugs like statins and other medications have helped mitigate some of these risks and control cholesterol levels, researchers are now investigating if a vaccine could be an even better option.

Researchers based in Austria and the Netherlands published the results of a mouse-based study today in the European Heart Journal, which found evidence that a vaccine can encourage the body to attack a certain enzyme called PCSK9. That enzyme is associated with higher levels of LDL or “bad’ cholesterol.

In the study the mice received the vaccine, called AT04A, which was designed to induce antibodies that target PCSK9. The mice that received the vaccine were found to have lower cholesterol, fewer inflammation markers, and less atherosclerotic damage in the blood vessels, than the control group during the 18-week study period.

While the study only focused on mice, researchers are now starting a phase I trial to see if the vaccine is safe and effective in humans as well.

Günther Staffler, PhD, CTO at AFFiRiS — the company that developed AT04A — and one of the authors of the study, said in a statement released today, that the levels of cholesterol were reduced in mice in a “consistent and long-lasting way.”

“The reduction in total cholesterol levels was significantly correlated with induced antibody concentration, proving that induced antibodies caused the reduction in cholesterol and also are ultimately responsible for the reduction of atherosclerosis development,” Staffler said in the statement.

Additionally, the researchers found evidence that the antibodies didn’t disappear quickly after the vaccine was given, with the levels of PCSK9 depressed for at least 18 weeks after vaccination.

“As antibody concentrations remained high at the end of the study, it can be assumed they would continue to reduce cholesterol levels for some time afterward, resulting in a long-lasting effect, as has been shown in previous studies,” Staffler continued.

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In an accompanying editorial, researchers from Germany and the United Kingdom said that as a result of the study results they would “promise to evaluate further” the long-term effects of lowering LDL cholesterol via vaccination.

They pointed out that a vaccine that could help prevent a build-up of LDL, and as a result possibly stop damage to the blood vessels via plaque build-up that can lead to heart attack or stroke.

However, they stress that the vaccine is unproven in humans.

“Safety, the response in humans, and the very important but unknown long-term immune effects, need to be very carefully addressed during the course of clinical development,” they noted.

Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, said that this study was “pushing the envelope” by taking the infectious disease vaccine model and applying it to treat cardiovascular disease.

“They have created a vaccine that in mice does indeed lower cholesterol and it results in reduced inflammation and reduced plaque formation, and it would appear to be, at least in this limited model, as something that’s worth trying out in humans,” Schaffner said.

Despite the interesting findings, Schaffner said there is no guarantee the findings will be replicated once humans receive the vaccine.

“All these concepts are exciting and proactive but we have to recognize when we move in the vaccine world … many vaccines are tried but very few result in products that work, I think the ratio is about 10 to 1,” he explained.

Oliver Siegel, the CEO of AFFiRis, said that they expect the initial phase I trial to be completed by the end of the year with the findings published as early as January next year. He also said that the vaccine may provide a better and cheaper option for people currently who have either not responded to statins or didn’t like taking them.

“What we see is that people don’t like taking a pill on a daily basis,” Siegel said. Should the vaccine prove to be safe and effective in humans, Siegel said they hope that people may not have to get more than one vaccination a year to keep their LDL cholesterol levels low.

However, Siegel stressed they must first determine that the vaccine works for humans in addition to mice.

“The key thing is this must be safe,” he said.

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