(Reuters) - Amgen Inc said on Thursday the U.S. Food and Drug Administration granted priority review to the company’s request to add important heart safety data to the label of its expensive injectable cholesterol drug Repatha.

FILE PHOTO: An Amgen sign is seen at the company's office in South San Francisco, California in this October 21, 2013 file photo. REUTERS/Robert Galbraith/Files

The FDA will decide by Dec. 2 whether to allow Amgen to include data from a major clinical trial that showed Repatha significantly cut the risk of heart attack, stroke and death in addition to dramatically lowering bad LDL cholesterol, the company said.

Amgen, which cannot promote the heart safety data until it is officially included in the prescribing information, sees the label update as critical to unlocking the value of a medicine seen as having multibillion-dollar sales potential.

“We look forward to working with the FDA to update the label for Repatha, enabling us to more broadly educate physicians and patients of the proven impact of Repatha to reduce cardiovascular events,” Amgen research and development chief Sean Harper said in a statement.

Repatha has had improving but anemic sales since its approval nearly two years ago on the basis of its LDL-lowering prowess, with second-quarter sales of just $83 million.

Insurers and pharmacy benefit managers have put up onerous roadblocks to patient access for the drug, with some 75 percent of prescriptions written being denied.

Amgen has said after discounts and rebates Repatha’s net price falls between $7,700 and $11,200 a year.

Clinical evidence that the injectable biotech drug does more than just lower LDL was considered necessary for payers to open their pocket books and start authorizing wider use.

In the study of more than 27,000 patients called Fourier that was released in March, Repatha cut the combined risk of heart attacks, strokes and heart-related death by 20 percent compared with a placebo in high-risk patients already on high doses of cholesterol-lowering statins, such as Pfizer Inc’s Lipitor.

In the second year of the study, the benefits were more pronounced, with a combined heart attack and stroke risk reduction of 33 percent.

Repatha and Praluent, sold by Regeneron Pharmaceuticals Inc and Sanofi, belong to a new class of medicines called PCSK9 inhibitors that block a protein that stops LDL from being removed from the blood.