So, who has heard of mucopolysaccharidosis VI (MPS VI)? Anyone? Anyone? Bueller?

MPS VI, also called Maroteaux-Lamy syndrome, is a very rare genetic disorder in which patients lack an enzyme that is needed to break down complex carbohydrates called glycosaminoglycans (GAGs). This disease is so rare that only an estimated 1,100 people in the developed world will have it. It is a very serious disease that primarily affects the skeletal system and joints. As I mentioned in a previous article, drug development efforts to treat patients with MPS VI and related disorders have been the strategic focus for companies like BioMarin Pharmaceutical (NASDAQ:BMRN), Genzyme (NASDAQ:GENZ), and Transkaryotic Therapies (NASDAQ:TKTX).

This morning, BioMarin released some highly anticipated data from its phase 3 trial of Aryplase in the treatment of MPS VI. The primary measure of efficacy was how far the patients could walk in 12 minutes. In this measure there was a statistically significant improvement seen in patients receiving Aryplase compared with those taking the placebo. This is an important result because it indicates that Aryplase improves the patient's ability to move around and function in daily life.

Administration of Aryplase is intended to restore the normal enzyme function to break down GAGs, and measuring the effect of Aryplase on GAG levels is an indicator of whether or not the drug has biological activity. In this measure, there was a highly statistically significant decrease in GAG levels in patients taking Aryplase compared with the placebo group. This strongly suggests that Aryplase is working as intended.

BioMarin is going to file for approval in the U.S. and Europe in the fourth quarter of this year. If the drug is approved, it would likely be on the market toward the end of 2005.

For those not familiar with these drug markets, I'm sure there is the question as to how such a small patient population can result in meaningful drug sales. From a commercialization perspective, these are attractive markets for small companies, as the enzyme replacement drugs on the market typically cost nearly $200,000 per year. With about 1,100 patients worldwide, the market is worth about $200 million.

Large drug companies may turn their noses up at such a market size, but for a small company such as BioMarin, that is a nice opportunity to move toward profitability. BioMarin has already identified nearly 200 of these patients, which should contribute to a successful launch of the drug should it be approved.

If drug stocks pique pique your interest, pay a visit to the Biotechnology board.

Fool contributor Charly Travers owns shares of BioMarin and Transkaryotic Therapies.