What happened

Amarin (NASDAQ:AMRN) stock soared 415% in September, according to data from S&P Global Market Intelligence. For context, the S&P 500 edged up 0.6% last month.

The Irish biotech company's stock has continued its upward march this month, with shares gaining 16.5% through Oct. 8. The broader market is down about 1% over this period.

Seven light gold-colored capsules on a flat surface.

Image source: Getty Images.

So what

We can attribute Amarin stock's incredible September performance to the company's release on Sept. 24 of extremely positive results of a cardiovascular outcomes study of Vascepa, its omega3 fatty acid drug derived from fish oil. "The study was evaluating the drug as an add-on to statin therapy in patients with elevated triglyceride levels," as my colleague George Budwell, who is one of the Fool's healthcare specialists, wrote at the time. 

The study showed that Vascepa (which received Food and Drug Administration approval in 2016 as a treatment for high triglyceride levels) reduced the risk of major adverse cardiovascular events by 25% in patients already taking statin drugs compared to those receiving a placebo, which is a highly statistically significant result. Armed with this strong trial result, Amarin "should now have little trouble getting Vascepa's label expansion approved in the United States," according to George. He noted that Amarin could potentially generate "up to a staggering $2 billion in sales with a broader label that includes patients with persistently high triglycerides despite being on statin therapy." 

That would surely be a particularly welcome boon for the company and its investors, as the stock has been struggling for a long time. Here's the 10-year stock picture:

AMRN Chart

Data by YCharts.

Now what

Amarin plans to release additional details from the study at the 2018 Scientific Sessions of the American Heart Association on Nov. 10 in Chicago. 

Market chatter is that the cardiovascular study's robust results make Amarin -- which sports a market cap of $5.6 billion -- a potentially attractive buyout target for a large pharma or biotech involved in the cardiovascular drug space.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.