BioMarin Pharmaceutical Inc. (Nasdaq and SWX: BMRN) today announced positive results from the Phase 3 extension study of rhASB (galsulfase), the company's investigational enzyme replacement therapy for the treatment of mucopolysaccharidosis VI (MPS VI). Data from the study demonstrate that patients who received rhASB for an additional 24 weeks, for a total of 48 weeks, continued to experience improved endurance. Patients who initially received placebo and then received rhASB for 24 weeks also experienced improved endurance. The data were presented by Stuart Swiedler, M.D., Ph.D., Senior Vice President of Clinical Affairs at BioMarin, at the annual meeting of the Society for Inherited Metabolic Diseases held in Pacific Grove, California.

Dr. Swiedler stated, "We are pleased to see continued benefit experienced by MPS VI patients receiving extended treatment with rhASB for MPS VI. The Phase 3 extension data further confirm the positive safety and efficacy profile of rhASB we have observed since the initiation of the clinical program, and we are working to make this therapy commercially available to individuals with MPS VI in the United States in the second half of the year."

Phase 3 Extension Study Design

All 38 patients who completed the initial 24-week, Phase 3, multi-center, double-blind, placebo-controlled trial were enrolled in the open-label extension study to further evaluate the safety and efficacy of rhASB. Patients who received rhASB during the initial 24-week, placebo-controlled portion of the trial continued to receive weekly 1.0 mg/kg infusions of rhASB in the extension study. Patients who initially received placebo during the placebo-controlled portion of the trial received 1.0 mg/kg of rhASB via weekly infusion during the extension study. Patients were evaluated at pre-defined, six-week intervals to assess changes in primary and secondary efficacy endpoints and the safety and tolerability of weekly rhASB infusions. Results of the study for the groups are summarized below:

Results from Patients Receiving 48 Weeks of rhASB

-- Patients demonstrated further improvement in endurance following an additional 24 weeks of treatment with rhASB as measured by the change in distance walked in 12 minutes, relative to baseline. From week 24 to week 48, patients receiving rhASB since week one of the trial improved their mean walk distance an additional 36 meters for a total of 145 meters for the 48-week period.

-- Patients demonstrated a further improvement in endurance following 48 weeks of treatment with rhASB as measured by the number of stairs climbed in three minutes, relative to baseline. From week 24 to week 48, patients receiving rhASB since week one of the trial improved their mean number of stairs climbed per minute by an additional 2.9 stairs for a total of a 10.4 stairs-per-minute improvement for the 48-week period.

-- The initial reduction in urinary glycosaminoglycan (GAG) levels, an in vivo measure of enzyme activity, was maintained from week 24 to week 48. Urinary GAG levels were reduced by 75.5 percent during the initial 24-week period.

Results from Patients Receiving 24 Weeks of rhASB

-- Patients initially receiving placebo demonstrated improvements in endurance following 24 weeks of treatment with rhASB as measured by the change in distance walked in 12 minutes, relative to baseline. From week 24 to week 48, the original placebo group demonstrated a mean increase of 65 meters relative to week 24 values.

-- Patients initially receiving placebo solution demonstrated an average improvement in endurance as measured by stairs climbed in three minutes, relative to baseline, of 5.7 stairs per minute following 24 weeks of treatment with rhASB.

-- Patients initially receiving placebo demonstrated a reduction in urinary GAG levels following 24 weeks of treatment with rhASB comparable to that observed for those treated in the initial 24-week, double-blind portion of the trial (p<0.001).

Data indicate that rhASB was generally safe and well-tolerated. The majority of adverse events reflected the underlying disease state or occurred during drug infusion. Over 95 percent of the infusion-related adverse events were considered mild or moderate and were easily managed. No patients discontinued rhASB infusions for adverse events and all patients that completed the double-blind portion of the trial continue to receive weekly infusions of rhASB. Nearly all patients developed antibodies as a result of treatment, but the level of the immune response did not correlate with adverse events or impact the improvements experienced in endurance.

About MPS VI

MPS VI (also known as Maroteaux-Lamy Syndrome) is a debilitating, life-threatening genetic disease for which no drug therapies are currently available. MPS VI is caused by a deficiency of the enzyme N-acetylgalactosamine 4-sulfatase, also known as arylsulfatase B. The deficiency leads to the accumulation of GAG in the lysosomes, the digestive organelles of the cell, giving rise to progressive cellular, tissue and organ system dysfunction. Debilitating symptoms can include impaired cardiac and pulmonary function, delayed physical development, skeletal and joint deformities, impaired vision and hearing, sleep apnea, and reduced endurance. The majority of subjects die from disease-related complications between childhood and early adulthood.

About BioMarin

BioMarin develops and commercializes innovative biopharmaceuticals for serious diseases and medical conditions. The company's product portfolio is comprised of two approved products, Orapred(R) (prednisolone sodium phosphate oral solution) for severe asthma and Aldurazyme(R) (laronidase) for mucopolysaccharidosis I (MPS I), and multiple investigational product candidates including rhASB (galsulfase), a Phase 3 product candidate for the treatment of mucopolysaccharidosis VI (MPS VI), and Phenoptin(TM) (sapropterin hydrochloride), a Phase 2 product candidate for the treatment of phenylketonuria (PKU). For additional information, please visit www.BMRN.com. Information on BioMarin's website is not incorporated by reference into this press release.

Forward-Looking Statement

This press release contains forward-looking statements about the business prospects of BioMarin Pharmaceutical Inc., including, without limitation, statements about: the development of BioMarin's product candidate rhASB; expectations related to extension arms of clinical trials of rhASB; and actions by regulatory authorities. These forward-looking statements are predictions and involve risks and uncertainties such that actual results may differ materially from these statements. These risks and uncertainties include, among others: the continued results of clinical trials; the content and timing of decisions by the FDA, the European Commission and other regulatory authorities concerning rhASB; and those factors detailed in BioMarin's filings with the Securities and Exchange Commission, including, without limitation, the factors contained under the caption "Factors That May Affect Future Results" in BioMarin's 2003 Annual Report on Form 10-K and the factors contained in BioMarin's reports on Forms 10-Q and 8-K. Stockholders are urged not to place undue reliance on forward-looking statements, which speak only as of the date hereof. BioMarin is under no obligation, and expressly disclaims any obligation, to update or alter any forward-looking statement, whether as a result of new information, future events or otherwise.

NOTE: Aldurazyme(R) is a registered trademark of BioMarin/Genzyme LLC.

Orapred(R) is a registered trademark of Medicis Pediatrics, Inc. and is used under license.

   Contacts:
   Investors
   Joshua A. Grass
   BioMarin Pharmaceutical Inc.
   415-506-6777

   Media
   Susan Ferris
   BioMarin Pharmaceutical Inc.
   415-506-6701

SOURCE: BioMarin Pharmaceutical Inc.