Regeneron, which is developing the drug, alirocumab, in partnership with Sanofi-Aventis SA (SNYNF), said the target date for a Food and Drug Administration approval decision was July 24, following a six-month review period.

That could put the medicine on the U.S. market a month ahead of Amgen’s rival evolocumab. Amgen was first to file its application, but received a standard 10-month review from the FDA, giving it an action date of Aug 27.

Regeneron and Sanofi, which were seen as lagging Amgen, employed an unusual strategy to catch up, purchasing a special priority review voucher from BioMarin Pharmaceutical for $67.5 million.

The drugs belong to a highly promising new class called PCSK9 inhibitors that block a protein that prevents the liver from removing bad LDL cholesterol from the blood. In clinical trials, they have shown an ability to lower LDL levels by more than 50%.

The injectable biotech medicines are expected to be used in high-risk heart patients who are unable to tolerate statins, such as Pfizer Inc.’s (PFE) Lipitor, or those who cannot get LDL levels low enough with statins. They are expected to be expensive, with analysts forecasting annual sales of $3 billion for each of the drugs.

Pharmacy benefit manager Express Scripts Holding said it was looking at the class with an eye toward negotiating a lower price from one company in exchange for priority status on its formulary for its millions of customers. Express used the strategy with new hepatitis C treatments, getting a lower price from AbbVie Inc. (ABBV) and excluding Gilead Science Inc.’s (GILD) drugs.

The first company to bring a PCSK9 drug to market would not only have a period to launch the medicine without competition, but would set the price for the class. Pfizer is also working on a PCSK9 drug that will likely be third to market.

Regeneron and Sanofi submitted an application for European approval of alirocumab earlier this month. The companies have proposed the brand name Praluent for their product once approved.