What: Shares of BioCryst Pharmaceuticals (NASDAQ:BCRX), a biotech company that specializes in the development of small molecular drugs, sank by over 20% today on heavy volume. The stock's sudden drops appears to be the result of a positive clinical update for BCX7353, an experimental treatment designed to reduce attacks stemming from a rare disorder known as hereditary angioedema, or HAE. Specifically, the company announced that a small, early stage study showed that BCX7353 significantly inhibited the target enzyme plasma kallikrein across all doses tested, and the drug was generally safe and well-tolerated.

So what: While it's somewhat unusual for a biotech's stock to plunge on positive trial results, BioCryst's case is unique because BCX7353 is facing stiff competition in its quest to treat HAE prophylactically.

Dyax's (UNKNOWN:DYAX.DL) DX-2930, for instance, showed such impressive early stage results earlier this year that the company decided to push the drug directly into a pivotal stage trial that is set to begin before the end of 2015.

Now what: So, perhaps the main reason BioCryst's shares are falling today is because the company is only advancing BCX7353 into a mid-stage trial, according to the press release--putting it well behind the rapid development of Dyax's competing therapy. In short, it looks like DX-2930 may end up claiming both the first-in-class and best-in-class trophies in the HAE race, casting doubt on BCX7353's commercial potential going forward. 


George Budwell 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.