Amgen and Regeneron are racing to develop medicines that cut cholesterol through a new strategy, by blocking a protein called PCSK9.

In earlier studies, both drugs cut levels of "bad" LDL cholesterol by up to two thirds, although Amgen's AMG 145 had been tested in healthy volunteers taking no other cholesterol medicines, while Regeneron's REGN 727 was tested in patients with high cholesterol that also took statins.

Amgen on Sunday reported its first results from an early-stage trial of AMG 145 in patients with high cholesterol also taking statins, and impressive findings were seen in those getting injections every two weeks or every month.

In the 51-patient study, patients receiving monthly injections of AMG 145 and taking low to moderate doses of statins had up to a two-thirds reduction in LDL cholesterol by the eighth week of the study.

"We gave two doses four weeks apart and at the eighth week there was minimal tapering off" of the drug's potency, Clapton Dias, Amgen's medical services director, said in an interview. "The 66-percent reduction of LDL was maintained."

In patients receiving injections of AMG 145 every two weeks in combination with low to moderate doses of statins, LDL reductions of up to 75 percent were seen after six weeks, Amgen said.

Those taking the Amgen drug every two weeks in combination with high doses of statins had LDL reductions of up to 63 percent.

Data from the Phase 1 study were presented at the annual scientific sessions of the American College of Cardiology being held in Chicago.

Researchers on Monday are slated to release the full data from a Phase II study of REGN 727, which Regeneron is developing in partnership with French drugmaker Sanofi. The findings will better enable investors to size up the pros and cons of the rival therapies.

Neither drug has so far shown any serious side effects in clinical trials.

GETTING EVERYONE TO GOAL?

Dias said the ability of drugs like AMG 145 to slash LDL beyond decreases attributed to statins such as Pfizer Inc's Lipitor could help enable millions of heart patients to finally get their cholesterol levels tightly controlled.

"A good 60 percent of high-risk patients in the United States are unable to meet their aggressive goals of getting LDL levels down" to target levels, Dias said, making them prime candidates for AMG 145 if it continues to do well in trials and is approved.

Steven Nissen, head of cardiology at the Cleveland Clinic, said anti-PCSK9 drugs, when used with statins, could eventually have a profound impact.

"If these drugs come to market, just about everyone with high cholesterol will be able to get to goal," Nissen said, with the possible exception of "several hundred" people with rare genetic conditions that would not benefit.

Industry analysts says PCSK9 inhibitors, if approved, could generate annual sales approaching $20 billion.

Nissen cautioned, however, that larger trials are needed to assess the safety of AMG 145 and REGN 727. He said a big question that remains is whether U.S. regulators would approve the drugs without first requiring major studies that evaluate long-term heart attack and stroke risk.

"That's the subtle wrinkle here," said Nissen, who speculated the U.S. Food and Drug Administration might be willing to approve them without such costly outcomes trials because statins were approved without them on the basis of their ability to lower cholesterol.

Nissen said statins and the PCSK9 inhibitors, although different classes of medicines, both exert their influence on the LDL receptor - a protein that carries LDL cholesterol through the bloodstream.

"So one could argue that PCSK9 uses the same pathway as statins," he said, a consideration that might score points with the FDA.

A four-week dosing schedule might be "modestly more attractive" to patients and doctors than injections every two weeks, Nissen said.

"But the frequency is not a make or break consideration," he added, because patients would be able to inject themselves with the same types of tiny needles that are already widely used and accepted for other conditions, including diabetes.

(Reporting by Ransdell Pierson, Editing by Gary Crosse)

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