Nothing has come easy for Amarin (Nasdaq: AMRN).

This manufacturer of the ultra-pure fish oil (EPA in particular) treatment Vascepa has garnered a devoted following of investors who believe that this is not just the next Lovaza (the purified fish oil treatment that Glaxo (NYSE:GSK) acquired in 2007 for $1.7 billion by buying Reliant Pharmaceuticals), but even more. Unfortunately for the bulls, Amarin has not yet garnered the new chemical entity (NCE) status from the FDA that would better shield it from competition, and interest in partnering or acquiring the company has been lackluster enough that the company has gone forward with its own marketing program.

Perhaps even worse, though, is the accumulation of data suggesting that fish oil may not be effective in reducing the risk of death from cardiovascular disease. On Wednesday, the New England Journal of Medicine reported results from the largest done to date on the efficacy of fish oil, and the results were not positive. The real questions for Amarin investors now are whether this trial is relevant to Vascepa and/or what impact it will have on real-world doctors.

The Biggest Study So Far Goes Belly Up For Fish Oil
The study in question is the Italian Risk and Prevention study – a study that enrolled over 12,500 patients with multiple cardiovascular risk factors and no prior history of heart attack. Patients in the study were randomized to receive either 1g/day of purified n-3 fatty acids or a placebo (olive oil) and then monitored for five years.

On first look, the results were not encouraging for the fish oil fans. Of the group receiving fish oil, 11.7% died or were hospitalized for cardiovascular issues. That compares to 11.9% for the placebo group - a difference that is not statistically significant. In other words, for the dose given, there is no statistical proof that fish oil can improve long-term risks of death due to cardiovascular disease (or other serious cardiovascular events like heart attack).

It's also important to note that this is not a unique result. While this was the biggest study done to date, earlier studies have delivered similar results – fish oil does not appear to reduce the risk of death from cardiovascular disease. While fish oil does consistently reduce triglycerides (and the effect was seen in this study as well), that reduction does not appear to lead to an actual clinical benefit.

SEE: Investing In The Healthcare Sector

Game Over For Vascepa? Not So Fast...
Certainly, any bad news for fish oil in general has spillover risk for Amarin and its Vascepa pill. To that end, the omega-3 market did decline by a high single-digit percentage in 2012 and seems to be on the same path in 2013. Amarin bulls, though, will argue that this study is not necessarily relevant to Vascepa and Amarin.

First, this study used 1g of n-3 fatty acids, which includes a mix of both EPA and DHA (the two most medically significant omega-3 fatty acids). Vascepa is basically pure EPA and the prescribing information calls for 4g per day. In other words, the Italian study used both a lower dose and a fish oil variety that contained more DHA – a fatty acid that can also increase the so-called “bad cholesterol”. To that end, I could see more risk from this study to Omthera (Nasdaq:OMTH) - another purified fish oil player (about 18 to 24 months behind Amarin), whose Epanova pill includes both EPA and DHA.

It's also worth noting that primary care physicians don't run their practices the same way as the well-known and well-respected thought-leader cardiologists do. Many of these physicians are creatures of habit, and many “manage to the numbers” and not to the outcome. What I mean is this – fish oil consistently reduces cholesterol numbers and that's the number that most doctors and patients track. So even though there is mounting clinical evidence that cholesterol numbers alone are not a great predictor of cardiac outcomes (LDL particle numbers appear to have more predictive value), doctors and patients have both effectively been trained that “lower is better”, and I suspect that there will be a lot of resistance to abandoning treatments that lower cholesterol.

As an aside, it may prove to be the case that the controversy over fish oil and the dichotomy between lower cholesterol numbers but no survival improvement focuses more attention on LipoScience (Nasdaq:LPDX) and its proprietary LipoProfile test (which measures the LDL particle number).

SEE: 5 Must-Have Metrics For Value Investors

Still An Uphill Battle
Although I can see how the particulars of this study (and the slow pace of change in real-world primary care) give Amarin some breathing room, I'm still not personally bullish on the company or the stock.

It is my personal opinion that while EPA may in fact be incrementally better than DHA, it's not going to be good enough to produce durable, statistically significant benefits. Moreover, I think new cholesterol treatments - particularly the PCSK9 inhibitors under development at companies like Amgen (Nasdaq:AMGN) and Sanofi (NYSE:SNY) – will garner significant attention and market share in the coming years. I also do think that the medical community is starting to sour on fish oil and that Amarin's more limited marketing capabilities will make it hard to reach or exceed Lovaza's peak sales.

The Bottom Line
Amarin isn't done yet. Fish oil treatments like Vascepa do offer an appealing side-effect profile and patient compliance is usually quite good as a result. What's more, expanded labeling tied to the results of the ANCHOR study could work in the company's favor. Still, I just don't see the data trending in the right direction here, and I think the growing marketing burden for Amarin is going to make it harder and harder for Vascepa to become a successful drug.

At the time of writing, Stephen D. Simpson did not own any shares in any company mentioned in this article.