Excitement following a filing for approval in Europe of Galafold, a treatment for Fabry disease, sent shares in Amicus Therapeutics (FOLD 1.98%) surging 14.9% higher in June.

The backstory
If European regulators approve Galafold, it will compete against Shire's Replagal and Sanofi's Fabrazyme, two Fabry disease therapies with combined global sales of $990 million last year.

Amicus Therapeutics' Galafold works differently than those two treatments. Replagal and Fabrazyme replace enzymes that are missing in Fabry disease patients, while Galafold helps the enzymes a patient still naturally produces work more efficiently.

Amicus Therapeutics estimates that roughly half of Fabry disease patients would benefit from Galafold therapy. However, because Galafold has a different mechanism of action, Amicus is also studying its use alongside Replagal and Fabrazyme. If those studies pan out, they could expand Galafold's addressable patient population to include all Fabry disease patients.

Source: Amicus Therapeutics,

Regardless, the appliSFYcation for European approval is likely to result in an EU decision early in 2016 on the drug's use as a monotherapy. That means that Amicus Therapeutics could begin recording sales from Galafold there within a year.

Looking ahead
Although the European market offers Amicus Therapeutics a solid revenue opportunity, approval in the U.S., where prices are typically higher, could significantly boost Galafold's peak sales potential.

Currently, Replagal and Fabrazyme each cost roughly $200,000 per year in America, and it's not a stretch to assume Galafold will be priced similarly.

Amicus expects to file for FDA approval by the end of this year, meaning it could conceivably be available in both Europe and America by 2017. For that reason, Amicus Therapeutics' stock might be worth owning.