Amarin (NASDAQ:AMRN) opened down 11% today after it disclosed in an SEC document that the Food and Drug Administration had rescinded the special protocol assessment for the biotech's triglyceride-lowering drug, Vascepa.

I'm shocked ... about the price drop, at least.

I'm not surprised the FDA would pull the SPA. It was painfully obvious that the agency had changed its view on whether lowering triglycerides improves cardiovascular outcomes since it established the agreement with Amarin in 2009.

A SPA is an agreement between a company and the FDA under which, if the company does everything that's asked and the data turns out as expected, the agency will approve the drug. But SPAs always comes with the caveat that the FDA isn't bound to approve the drug if the situation changes.

In 2009, the FDA believed it was reasonable to assume that lowering triglycerides would improve cardiovascular outcomes. The company asked Amarin to conduct a trial to confirm the hypothesis and said it would approve Vascepa for patients with moderately high triglyceride levels after the outcomes trial was substantially enrolled.

Unfortunately, a few trials have since shown that lowering triglyceride levels isn't sufficient to reduce the number of adverse cardiovascular events such as heart attacks and strokes. The ACCORD-Lipid trial showed that triglyceride levels improved when patients were given AbbVie's (NYSE:ABBV) Tricor, but the drug had no effect on adverse cardiovascular events. Another trial, called AIM-HIGH -- testing the organic compound niacin like what's in AbbVie's Niaspan -- also failed to show better outcomes for patients taking the drug. Merck (NYSE:MRK) had a similar result with its niacin-containing Cordaptive; the drug failed to improve outcomes despite improving both triglyceride and cholesterol levels.

Holding out hope
While the FDA's decision didn't surprise me, I am a little surprised by the price decline today. Without the SPA, Amarin clearly has no shot at getting Vascepa approved to treat patients with moderately high triglyceride levels.

But even with the SPA still in place, the FDA was obviously against the expanded authorization, and after a substantially negative advisory panel meeting Amarin already had no shot at getting Vascepa approved. Pulling the SPA is just the last nail in the coffin. It doesn't change anything because Vascepa's chances for expanded approval were already killed by the trials run on AbbVie's and Merck's drugs.

Buying opportunity?
Amarin still has a chance to expand the use of Vascepa into patients with moderately high triglyceride levels if the outcomes trial is positive. Vascepa works in a different way than AbbVie's Tricor and Niaspan and Merck's Cordaptive, so it's conceivable that Vascepa could improve outcomes even though the others didn't. Unfortunately, the trial won't read out until late 2015 at the earliest and could take until 2017 if Amarin has to wait for the final results.

If you thought Amarin was fairly priced yesterday, I guess today's discount makes it a good deal, but you're going to need to be willing to hold for years to see major gains.

Fool contributor Brian Orelli has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.