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A treatment for the most common cause of dwarfism met its goal of increasing height in a pivotal study, the drug’s maker said Monday, setting the stage for Food and Drug Administration approval.

The company, BioMarin, enrolled 121 children with achondroplasia, the most common cause of dwarfism. Those who got the treatment, called vosoritide, grew 1.6 centimeters more over the course of a year than those who received placebo, BioMarin said. That’s enough to declare the trial a success, but it falls below the 2 centimeters that Wall Street analysts had expected. The company didn’t disclose any other data from the study but said there were no serious side effects associated with vosoritide.


Next year, BioMarin will begin making its case to global regulators, advancing a debate that has been polarizing among people with dwarfism. To many, vosoritide’s effect on height is reason enough to approve the drug, as it might provide long-term relief from skeletal problems, hearing loss, and other complications brought by achondroplasia. To others, approving a treatment that has proved only to make children taller threatens to undermine years of advocacy without offering a guaranteed benefit.

The final decision will fall to regulators. BioMarin expects to file vosoritide for FDA approval next year. The agency has said it would approve a treatment for achondroplasia based on height. It is likely to convene a panel of expert advisers before deciding on vosoritide, a meeting that would invite public comment from those who support the drug and those who stand against its approval.

In the meantime, BioMarin has promised to present full data from its pivotal trial at a later medical meeting. That presentation could answer key questions about growth velocity and safety.


Vosoritide is a daily injection meant to counteract the genetic mutation that causes achondroplasia. The condition results from an error in a gene called FGFR3, which regulates bone growth. For patients with achondroplasia, the natural process by which cartilage turns into bone is interrupted, resulting in shorter stature, a bowing of the spine, and the risk of serious medical complications.