1st drug to treat genetic cause of dwarfism approved by FDA

The Food and Drug Administration (FDA) has approved the first drug to treat the most common form of dwarfism, known as achondroplasia.

Achondroplasia is caused by mutations in the FGFR3 gene, which encodes instructions to build a protein involved in bone growth and development, according to the Genetic and Rare Diseases Information Center. These mutations push the gene into overdrive, studies suggest, which impedes the process by which cartilage tissue gets replaced by bone; this leads to the development of short and abnormally-shaped bones and causes people with achondroplasia to be of short stature. In addition to dwarfism, the mutations can cause health complications, such as sleep apnea, recurrent ear infections, a build-up of fluid in the brain and skeletal problems that require surgery to correct.

BioMarin Pharmaceutical, a U.S.-based company, has been developing and testing a treatment for achondroplasia for years, STAT News reported in 2019. Now, as of Friday (Nov. 19), that drug has officially been approved for use in children ages 5 and up, according to a statement from the FDA. 

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Clinical trials suggest that the drug, called Voxzogo, is safe and effective at restoring bone growth in children with achondroplasia and thus boosting their heights; but it's unclear whether the drug also counteracts the various health issues that can arise from the condition, STAT News reported Friday. 

Voxzogo, also known by the generic name vosoritide, works by binding to a receptor called natriuretic peptide receptor-B that is found in bone and cartilage tissues. Once attached to this receptor, the drug sets off a chain reaction that stimulates bone growth and overrides the effects of the FGFR3 mutations, according to a statement from BioMarin Pharmaceutical. 

The most recent trial of Voxzogo included 121 participants between the ages of 5 and 18 whose growth plates were still open, meaning they hadn't finished growing. The participants were randomly assigned to receive either one daily Voxzogo injection or a placebo shot, and the trial organizers assessed all the children's rate of height growth over the course of a year. 

The most common side effects of the treatment included injection site reactions, such as redness or itchiness, vomiting and decreased blood pressure, according to the FDA. By year's end, participants who received the drug grew an average 0.6 inches (1.57 centimeters) taller compared with those who received a placebo. According to BioMarin Pharmaceutical, this data suggests that, if treated throughout their childhoods, kids with achondroplasia could reach similar heights as children without the condition, STAT News reported. 

Now that it's approved, Voxzogo should be available in the U.S. this December, according to BioMarin Pharmaceutical. The list price for a year-long course of the treatment is $320,000. 

Within the dwarfism community, Voxzogo has historically drawn mixed reactions, according to STAT News. Some have expressed concern that the clinical trials exclusively focused on participants' heights, rather than their long-term health; in this way, the drug seems aimed at "correcting" short stature, which they argue isn't a problem that requires fixing. Other little people have expressed hope that the treatment will help improve people's quality of life by warding off the potential health complications of achondroplasia.

Read more about Voxzogo's recent approval and reception at STAT News. 

Originally published on Live Science.