The U.S. Food and Drug Administration (FDA) has granted accelerated approval to vosoritide (Voxzogo), indicated to increase linear growth in pediatric patients 5 years of age or older with achondroplasia with open epiphyses.
Achondroplasia is a skeletal dysplasia characterized by the failure of normal conversion of cartilage into bone, most notably in longer bones, which results in disproportionate short stature. Achondroplasia is caused by a mutation in the FGFR3 gene, which causes the FGFR3 protein to be overly active. People with achondroplasia can experience serious health complications, including foramen magnum compression, spinal stenosis, sleep apnea, bowed legs, mid-face hypoplasia, permanent sway of the lower back, recurrent ear infections, and long term chronic pain.
Vosoritide is the first FDA approved treatment for children with achondroplasia. As a C-type natriuretic peptide (CNP) analog, vosoritide represents a new class of therapy, which acts as a positive regulator of the signaling pathway downstream of FGFR3 to promote endochondral bone growth.
Approval for vosoritide was based on the outcomes of a global randomized, double-blind, placebo-controlled phase 3 study evaluating the efficacy and safety of vosoritide and the open-label extension of this study. The phase 3 study enrolled 121 children aged 5 to 14.9 with achondroplasia. Baseline mean AGV in the placebo and vosoritide groups was 4.06 cm/year and 4.26 cm/year, respectively. At week 52, the change from baseline in AGV was -0.17 cm/year for the placebo treated patients and 1.40 cm/year for the vosoritide treated patients, resulting in a statistically significant improvement in AGV of 1.57 cm/year in favor of vosoritide. After the 52 week double blind, placebo–controlled study, 58 subjects who were initially randomized to vosoritide enrolled into an open–label extension. Among the subjects who had two years of follow–up since randomization, the improvement in AGV was maintained.
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