Biomarin

(BMRN) - Get Report

was the second most-heavily traded stock in Thursday's premarket session after the company said its treatment for an often fatal genetic disorder that saps cardio-pulmonary vigor caused a statistically significant improvement in patients' ability to walk for 12 minutes.

Biomarin's lead drug candidate, Aryplase, is an enzyme replacement therapy for treatment of mucopolysaccharidosis VI, or MPS VI, a rare disease that causes deterioration of cell organs and gives rise to progressive cellular, tissue and organ debilitation. Most people with the disease die from related complications between childhood and early adulthood.

The stock was recently up $1.07, or 16%, to $7.60 on the Instinet premarket.

In a multi-center, double-blind trial of 39 patients, ranging in age from 5 to 29 years, the drug was shown to create a statistically significant enhancement of its primary endpoint: distance walked over 12 minutes. There was also a statistically significant reduction in the buildup of glycosaminoglycans in patients' urine, and a positive trend in a test called the three-minute stair climb.

Aryplase was generally safe and well-tolerated in the study.

The company said it has identified more than 200 patients who could potentially benefit from the treatment, which reportedly will cost about $170,000 a year.

"Our recently acquired 66-person pediatric sales force is now planning educational campaigns targeting pediatricians and medical geneticists in the United States to raise awareness about MPS VI and other lysosomal storage diseases and metabolic disorders," the company said.