By Bill Berkrot and Ransdell Pierson
DALLAS, Nov 19 (Reuters) - Amgen Inc's experimental heart medicine from a closely watched new class of drugs called PCSK9 inhibitors lowered "bad" LDL cholesterol 52 percent after one year with no major increase in serious adverse side effects compared with standard drugs, such as statins, according to data from a study.
The clinical trial of the drug, evolocumab, marks the first data looking at 52 weeks of use for the new class of injectable biotech medicines seen as potentially the biggest advance in the field of cholesterol therapy in many years.
Several companies are developing the drugs, which work by blocking a protein that prevents the liver from removing LDL cholesterol from blood. In addition to Amgen, Pfizer Inc and Regeneron Pharmaceuticals Inc in partnership with Sanofi are in advanced stages of testing PCSK9 inhibitors.
They are most likely to be used in patients who cannot tolerate statins or those whose LDL cholesterol remains too high even after being treated with high potency statins.
"The results from the Osler study are encouraging as evolocumab may offer a potential treatment option for patients who cannot control their cholesterol levels," said Dr. Michael Koren, the study's lead investigator, who presented the data on Tuesday at the American Heart Association (AHA) scientific meeting in Dallas.
The 1,104-patient trial tested 420 milligrams of evolocumab injected once a month in addition to standard therapy with statins or other medicines versus standard of care drugs alone.
After 52 weeks, those who took the Amgen drug saw their LDL levels drop 52 percent on top of statins, which was considered by researchers to be highly statistically significant.
Levels of other blood lipids also moved in the beneficial direction, researchers said. Triglycerides went down about 9 percent and "good" HDL went up about 9 percent.
Patients in the Osler extension study had previously completed participation in one of four 12-week Phase II studies of the drug.
Serious adverse side effects occurred in 7.1 percent of patients treated with evolocumab and standard care compared with 6.3 percent for those who got standard therapy alone.
Side effects such as elevated liver enzymes were similar - 1.8 percent for evolocumab versus 1.6 percent in the control group - and a measure of potential kidney problems was 1 percent compared with 1.9 percent.
The serious side effects were not felt to be related to evolocumab, said Koren, of the Jacksonville Center for Clinical Research in Florida. He added that adverse heart events, such as heart attacks, were slightly higher in the standard of care patients.
"It did wonderfully," Koren said of the Amgen drug, "This gives us a much greater comfort level about possible safety signals."
That may play a pivotal role in whether drugs from this class can be approved without long-term, "outcomes" studies that definitively show whether they can reduce the risk of heart attacks, strokes and deaths.
New cholesterol management guidelines released last week by the AHA and American College of Cardiology only backed therapy with medicines that had demonstrated a reduction in heart risk, such as statins.
That called into question whether the U.S. Food and Drug Administration would still be willing to approve drugs based on so-called surrogate end points, such as lowering LDL levels.
An FDA official last week said the agency might be willing to approve the PCSK9 drugs without outcomes data if they did not show any unexpected toxicities.
"I know with fairly good confidence that The FDA believes in LDL," Koren said.
"There's tremendous excitement," he said of the new class of drugs. "This is the biggest thing to happen to lipid treatment since statins."