What's happening: BioMarin Pharmaceutical (NASDAQ:BMRN) shares increased by 10% earlier today following positive midstage trial results being released for its BMN-111, a treatment for children with achondroplasia -- the most common form of human dwarfism.

Why It's happening: BioMarin Pharmaceutical is one of the most successful developers of therapies for rare disease, and the results from this trial suggest that BMN-111 could end up being yet another important win for the company.

BMN-111 is a stabilized formulation of C-type natriuretic peptide, a naturally occurring human peptide that helps promote bone growth.

In this phase 2 study, 10 achondroplasia patients taking a 15 microgram per kilogram dose per day of BMN-111 showed an average increase of 50% in annualized growth velocity versus their prior six month annualized growth velocity. That's enough of an improvement, if it's maintained, for BioMarin to suggest that BMN-111 could allow the roughly 24,000 patients under 18 with this condition to resume a normalized growth rate.

BioMarin plans to sit down with regulators and create a plan to move the 15 microgram dose of BMN-111 into phase 3 trials that, if successful, could lead to an eventual FDA approval. BioMarin also intends to explore whether or not a higher dose of BMN-111 could enable "catch-up" growth in the event of delayed treatment.