FDA Approves Vosoritide for Children With Achondroplasia

The US Food and Drug Administration (FDA) has approved vosoritide (Voxzogo) daily injection for the treatment of children with achondroplasia, the most common form of human dwarfism.

The indication is for children aged 5 years and older who have achondroplasia and open epiphyses (growth plates), meaning that they still have the potential to grow.

Achondroplasia is caused by a mutation in the fibroblast growth factor receptor 3 (FGFR3) gene that leads to inhibited mineralization of chondrocytes (cartilage cells) in the growth plate.

The mutation occurs in about 25,00 live births worldwide, resulting in disproportionately short stature and disordered architecture of the long bones, spine, face, and base of the skull. Affected children have an average-sized torso, short arms and legs, and an enlarged head.

Vosoritide, a biologic analogue of C-type natriuretic peptide, prevents the inhibition of mineralization of chondrocytes caused by the FGFR3 mutation.

“Today’s approval fulfils an unmet medical need for more than 10,000 children in the United States…. With this action, children with short stature due to achondroplasia have a treatment option that targets the underlying cause of their short stature,” said Theresa Kehoe, MD, director of the Division of General Endocrinology in the FDA’s Center for Drug Evaluation and Research, in a statement.

Lynda Polgreen, MD, an investigator in clinical trials for vosoritide, agrees: “This approval is an important milestone representing the first time that physicians will be able to offer a therapy targeted at the root cause of the condition for families of children with achondroplasia aged five and older,” she noted in a BioMarin press release.

“Achondroplasia is a lifelong genetic condition resulting from the disordered skeletal architecture caused by impaired endochondral bone growth throughout childhood,” added Polgreen, of the Lundquist Institute at Harbor and associate professor at the David Geffen School of Medicine, University of California, Los Angelas.

The approval was based on data from a year-long, double-blind, placebo-controlled phase 3 study in 121 children aged 5–17 years with open epiphyses. The patients were randomly assigned to receive injections of vosoritide or placebo. Those who received the drug grew an average of 1.57 cm (0.6 in.) taller compared to the control patients.

The most common side effects were injection site reactions, vomiting, and reduced blood pressure. These reactions are listed on the label as a warning and a precaution.

Vosoritide was approved under FDA’s accelerated approval pathway, which allows for earlier approval of drugs to treat serious conditions and that fill an unmet medical need. Such approvals are based on surrogate or intermediary endpoints. The company will now be required to conduct a postmarketing study to assess final adult height.

“We applaud the FDA for recognizing the urgent unmet medical need for this progressive condition. As a parent of a child with achondroplasia, I see the availability of treatments that impact bone growth as an important step forward,” said Amer Haider, co-founder of Growing Stronger, an organization with a mission to improve the quality of medical care for little people through supporting research, in the company press release.

Growing Stronger raises nonprofit donations that are granted to researchers focused on dwarfism.

Vosoritide is expected to be available in the United States by mid- to late-December, and BioMarin will begin the promotion of it immediately.

The product was approved by the European Commission in August 2021, and marketing authorization reviews are in process in Japan, Brazil, and Australia. Approvals may be granted in these countries in 2022.

Miriam E. Tucker is a freelance journalist based in the Washington DC area. She is a regular contributor to Medscape, with other work appearing in the Washington Post, NPR’s Shots blog, and Diabetes Forecast magazine. She is on Twitter @MiriamETucker.

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