Shares of Aegerion Pharmaceuticals (NASDAQ:AEGR)hit a new 52-week high in intra-day trading on Friday. The company hadn't announced any information about its lead drug lomitapide. But a potential competitor from Isis (NASDAQ:IONS) and Sanofi (NYSE:SNY) received a negative recommendation from a European Medicines Agency committee, citing safety concerns. This bump was temporary, but the EMA info adds to past events to spell trouble for Kynamro -- and a potential win for Aegerion.

So what? 
Lomitapide and Kynamro treat homozygous familial hypercholesterolemia (HoFH) -- or severely high cholesterol. The drugs have run nearly parallel down the pipelines, making an event for one reflect almost immediately upon the other. And the drugs have both proven effective , meaning the final battle panel will play out in the arena of safety.

It's a battle that Kynamro may lose. The drug's latest setback is the EMA committee "nay."  Safety concerns aren't surprising; both drugs have faced safety questions along the way. But a Kynamro-specific concern could become the decider.

Both HoFH drugs went before FDA advisory panels in October, appearing on consecutive days. Aegerion was up first, and shares rose 13% upon the approval recommendation, despite concerns about potential liver risks. Kynamro also received a recommendation, but Isis shares fell 20%,  due to additional concerns raised by its panel. As the Fool's Sean Williams wrote, the panel detailed Kynamro's risk of abnormal tissue growth that appeared in 3.1%  of the trial's patients.

Now what? 
The time for the FDA's decisions is upon us. Aegerion should receive word by the end of this month,  and Isis should come in late January . Investors need to keep a close watch on the results of these decisions.

Brandy Betz has no positions in the stocks mentioned above. The Motley Fool has no positions in the stocks mentioned above. 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.