You win some, you lose some. And sometimes you do both.

Protalix BioTherapeutics (NYSE: PLX) and Pfizer's (NYSE: PFE) Gaucher disease treatment, taliglucerase alfa, was given a positive assessment by the European Medicines Agency's Committee for Medicinal Products for Human Use, or CHMP. But the agency didn't recommend that the drug be approved.

It appears the EU agency is following the letter of the law, which gives Shire Pharmaceuticals (Nasdaq: SHPGY) a 10-year exclusivity on Gaucher disease treatments after its 2010 approval of Vpriv. The exclusivity is a result of Vpriv's orphan drug status, which provides exclusivity as an incentive to develop drugs for rare diseases.

Pfizer and Protalix could have gotten around the exclusivity if they could have shown that taliglucerase was superior to Vpriv or that there was a supply constraint of Gaucher drugs that taliglucerase could fill. CHMP concluded that neither was the case.

The next step is for the EMA to ratify CHMP's recommendation, although Pfizer and Protalix can -- and probably will -- appeal the decision. The company's best option might be to sit tight and hope the supply becomes constrained again. A few years ago, Genzyme, now part of Sanofi (NYSE: SNY), ran into problems making its Gaucher treatment, Cerezyme, and is just now recovering.

Pfizer and Protalix's drug was recently approved in the U.S., where Cerezyme remains supply constrained. Once the Sanofi gets Cerezyme back to full production, the companies plan to compete on price; the drug, which goes by the brand name Elelyso, will be 25% cheaper than Cerezyme.

Considering their moves in the U.S., Pfizer and Protalix might not be missing all that much by not gaining approval in the EU, where the profit margins tend to be slimmer. Competing in the EU would probably be an even tougher task than the duo faces in the United States.

I guess we'll find out in eight years, when Shire's exclusivity runs out.

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