Shares in BioMarin rocketed more than 30% yesterday as investors reveled in news that its lysosomal storage disorder drug turned in an impressive performance in a late-stage clinical trial, pushing it closer to market.

The company said that a Phase III clinical trial assessing its experimental therapy GALNS in patients with the rare lysosomal storage disorder Mucopolysaccharidosis Type IVA (MPS IVA), which is also known as Morquio A Syndrome, met its primary endpoint.

In the MOR-004 study, 176 patients with the condition were randomised to receive infusions of GALNS either every week or every other week, or a placebo.

According to the data, at 24 weeks patients taking a weekly dose of the drug showed a significant improvement of 22.5 metres in the six minute walk test compared to those in the control arm.

On the secondary endpoint of three-minute stair climb, patients given weekly GALNS showed a trend toward improvement at 24 weeks of 1.1 additional stairs per minute over placebo.

In addition, preliminary data from an extension trial (MOR-005) suggest that the drug's benefit was continued after 36 and 48 weeks of therapy, the firm noted.

Submissions from early next year

On the back of these results, the company said that it expects to submit marketing applications to regulatory authorities starting in the first quarter of 2013, and analysts seem relatively confidents in its approval.

"Given this is the largest Phase III enzyme replacement therapy conducted to-date, being statistically significant on the primary endpoint should strongly support approval," noted Michael Yee, analyst at RBC Capital Markets.

It is estimated that there are around 3,000 patients with the condition worldwide, and analysts are forecasting peak sales of around $800 million.