FDA Assigns Target Date for Voxzogo in Young Children with Dwarfism

The FDA) has accepted the BioMarin Pharmaceutical’s supplemental new drug application (sNDA) for Voxzogo (vosoritide) for injection to expand treatment in the United States to include children with achondroplasia under the age of 5. Achondroplasia is the most common form of dwarfism. The FDA has set a PDUFA target action date of Oct. 21, 2023, for the sNDA.

“There are currently no approved pharmacological treatments in the United States for children under 5 with achondroplasia and this approval could potentially extend access to all children with achondroplasia, whose growth plates are not closed,” Hank Fuchs, M.D., president, Worldwide Research and Development at BioMarin, said in a press release.

In patients with achondroplasia, endochondral bone growth, an essential process by which bone tissue is created, is affected by a mutation in fibroblast growth factor receptor 3 gene (FGFR3). More than 80% of children with achondroplasia have parents of average stature and have the condition as the result of a spontaneous change in the gene. The worldwide incidence rate of achondroplasia is about one in 25,000 live births.

Voxzogo, a C-type natriuretic peptide (CNP) analog, acts as a positive regulator of the signaling pathway downstream of FGFR3 to promote endochondral bone growth. It received accelerated approved by the FDA to increase growth in pediatric patients with achondroplasia who are 5 years of age and older with open epiphyses, which are growth plates that haven’t fully formed.

As of December 2021, Voxzogo’s list price was $8,990 for 10 single-dose vials. BioMarin offers a copay assistance program that covers up to $17,000 a year

The sNDA is supported by results from a phase 2 clinical trial, which demonstrated similar safety and efficacy profiles in children under 5 years of age as compared with those ages 5 years and older. The study showed an improvement in height Z-score (a measure of height adjusted for age and sex in reference to the average stature population and reported as a Standard Deviation compared with placebo at 52 weeks. Voxzogo increased height Z-score by 0.30 standard deviation and annualized growth velocity by 0.92cm/year. This improvement in height Z-score was consistent with improvements seen in patients over five years of age.

The safety profile was consistent with that seen in older patients. The most common adverse events were mild and self-limiting injection site reactions