AstraZeneca Plc has signed a deal with Avanir Pharmaceuticals to develop a new kind of drug that may reverse cholesterol build-up inside blood vessels.

The idea is to treat cardiovascular disease by targeting a biological pathway that enhances the flow of cholesterol away from blood vessel walls, where it can lead to the build-up of life-threatening plaques.

If successful, this could potentially reverse existing vascular disease, while current agents have to date been shown only to prevent disease progression.

Because of the novel action, so-called Reverse Cholesterol Transport (RCT) medicines may eventually be given in addition to existing cholesterol drugs, which work by either inhibiting the synthesis of cholesterol or by blocking its absorption from the gut.

AstraZeneca, which already sells the cholesterol fighting statin drug Crestor, will be responsible for developing the new generation of RCT enhancing compounds discovered by Avanir scientists.

Lipitor is used for those who have abnormally High cholesterol levels. When taken together with a low-fat diet, this medicine can effectively reduce LDL cholesterol, commonly referred to as the “bad” cholesterol, triglyceride levels, and total cholesterol, while increasing the HDL, or “good” cholesterol.

Europe’s third largest drugmaker said on Monday that Avanir could receive milestone payments of $330 million under the deal, in addition to an upfront payment of $10 million, lifting shares in the U.S. firm by around 5 percent.

The San Diego, California-based company will also be entitled to stepped royalties, rising from single-digit to low double-digit percentage rates depending on sales achieved.

But those payouts depend on the drug being approved and launched, which is still many years away, since the partners only expect to be ready to apply to start testing their experimental medicine in humans later this year.

Other companies are also working on ways to improve the body’s removal of “bad” LDL cholesterol. Pfizer Inc is currently undertaking final phase III studies of torcetrapib, a new drug that works by blocking a protein in the liver that transfers cholesterol.

An AstraZeneca spokesman said Avanir’s RCT approach was more direct in its action, since it mimicked a naturally occurring body process to remove bad cholesterol.