(Reuters) - Shares of Amarin Corporation Plc fell 20 percent on Friday on concerns the U.S. Food and Drug Administration will reject its application to market Vascepa, a drug that lowers blood fat levels, to a broader patient population.
Staff reviewers for the FDA posted their assessment of Amarin's application on the agency's website on Friday, and some analysts said the review appeared more cautious than they had expected.
Vascepa is currently approved as a stand-alone treatment to lower high levels of triglycerides, or blood fats, which can raise the risk of heart disease.
Amarin is hoping to win approval to also market it for patients with blood fat abnormalities who are at high risk of coronary heart disease and are already taking a statin, such as Pfizer Inc's Lipitor, to reduce cholesterol.
An outside panel of advisers to the FDA will discuss Amarin's application and recommend whether it should be approved on Wednesday.
"Some FDA commentary is bullish and suggests non-approval would deviate from precedent," said Joseph Schwartz, an analyst at Leerink Swann, in a research note, "but other language is bearish."
At issue is whether the FDA panel will be satisfied with data showing the drug lowers triglycerides, or whether it will demand additional data from an ongoing trial of 8,000 patients that is expected to show whether the drug cuts the rate of cardiovascular events and death.
Writing for the FDA, Dr. Mary Dunne Roberts said that with rare exceptions, the agency "has historically considered granting approval for lipid-altering drugs based on favorable changes in the lipid profile, with the assumption that these changes would translate into a benefit on clinical outcomes."
On the other hand, Roberts said, a number of recent large cardiovascular outcome trials "have failed to demonstrate a reduction in residual cardiovascular risk with non-statin lipid-altering treatment."
Winning approval for the expanded indication "is critical for long-term Vascepa sales growth," Thomas Wei, an analyst at Jefferies LLC said in a recent research note. "We view it as central to our Amarin Buy thesis."
He said he was optimistic that the panel would recommend approval. "The historical track record of this panel and this division of the FDA is encouraging, with similar debates generally favoring the approval of diabetes and obesity drugs in the absence of cardiovascular outcomes data."
Amarin's shares fell $1.28 to close at $5.09 on the Nasdaq stock exchange.
Vascepa is a purified ethyl ester of eicosapentaenoic acid (EPA) derived from fish oil. It was approved in July 2012 for severe hypertriglyceridemia as an adjunct to diet.
About 21 percent of U.S. adults have mixed dyslipidemia, defined as high levels of "bad" LDL cholesterol combined with at least one other lipid abnormality, the FDA said.
EPA, along with a-linolenic acid and docosahexaenoic acid (DHA) are collectively referred to as omega-3 fatty acids. EPA and DHA are also the major constituents of fish oils derived from cold water fish.
(Reporting by Toni Clarke in Washington; Editing by Leslie Adler)