NOVATO -- BioMarin Pharmaceutical Inc. (Nasdaq: BMRN) today announced it started a phase 3 trial for N-acetylgalactosamine 6-sulfatase, named GALNS or BMN 110. It's intended for the treatment of the lysosomal storage disorder Mucopolysaccharidosis type IVA, or MPS IVA, also called Morquio A syndrome.

"In under two years, we have progressed the GALNS program from clinical trial application to initiation of the phase 3 trial," said Jean-Jacques Bienaime, chief executive officer. "We have received FDA feedback and have finalized the design of the phase 3 pivotal trial."

A phase 3 trial is a randomized, double-blind, placebo-controlled study to evaluate efficacy and safety.

The BMN 110 study is the largest enzyme-replacement therapy trial ever conducted, according to the company. It will be conducted at about 40 centers worldwide, including Brazil, Japan, Taiwan, most Western European countries, Canada and the U.S. The trial is expected to enroll about 160 subjects.

There are no therapeutic options for MPS IVA patients who have a high unmet medical need, Mr. Bienaime said.

The 24-week study will explore a weekly dose of 2 milligrams per kilogram of patient weight and a biweekly treatment with 2 milligrams per kilogram. Patients will be evaluated primarily with a six-minute walk test and secondarily with a the three-minute stair climb test and analysis of urine keratan sulfate concentration.

MPS IVA affects an estimated 2,500 to 3,500 patients worldwide, including 1,000 to 1,500 in the U.S., EU and Japan and 1,500 to 2,000 patients in the rest of the world. Several studies documented the incidence as high as 1 in 76,000 live births in Northern Ireland.

The disease results from deficient activity of the enzyme N-acetylgalactosamine 6-sulfatase, or GALNS. That causes excessive lysosomal storage of keratan sulfate. Such excessive storage causes a systemic skeletal dysplasia, short stature and joint abnormalities, which limit mobility and endurance. Malformation of the thorax impairs breathing. Odontoid hypoplasia and ligamentous laxity can damage the spinal cord. Other symptoms may include hearing loss, corneal clouding and heart valvular disease.

Initial symptoms often become evident in the first five years of life.