What happened

Shares of Amarin (NASDAQ:AMRN) rose over 15% today after the company announced that the U.S. Food and Drug Administration (FDA) granted priority review for Vascepa's supplemental new drug application, which seeks to allow the drug to be marketed for its ability to reduce cardiovascular risks. The Prescription Drug User Fee Act (PDUFA) date is set for September 28, or four months earlier than expected without priority review.

The FDA agreed to grant priority review after Vascepa delivered a 25% relative risk reduction, compared to placebo in the first occurrence of a major adverse cardiovascular event in the REDUCE-IT trial. If approved, Vascepa would become the first drug "indicated to reduce residual cardiovascular risk in patients with statin-managed LDL-C cholesterol, but persistent elevated triglycerides."

As of 11:25 a.m. EDT, the stock had settled to a 12.7% gain.

A businessman holding a computer and riding a cartoon rocket, with clouds and stars painted on a back wall.

Image source: Getty Images.

So what

Why is a four-month speed up such a big deal? Well, the application is considered "supplemental" because Vascepa has already been approved for lowering very high triglyceride levels. But earning the cardiovascular risk reduction indication would make that the primary driver of the drug's fortunes.

Case in point: Approval could help Vascepa reach peak annual sales approaching $10 billion. It generated revenue of $228 million in 2018.

Now what

Investors were already fairly confident in the future of Vascepa, which seems destined to become a blockbuster drug given the information available. Today's news indicates that confidence was well-placed, although earning priority review doesn't necessarily mean the drug will earn marketing approval from the FDA.

All investors can do is wait until September 28 for the next major update.