FDA Approves Vosoritide Injection for Treatment of Children With Achondroplasia

Today, the US Food and Drug Administration (FDA) announced the approval of vosoritide (VOXZOGO) injection to improve growth in children aged 5 years or older with achondroplasia and open epiphyses.

The approval of the first agent to treat achondroplasia in children was granted to BioMarin Pharmaceutical. It was approved under accelerated approval based on improvement in annualized growth velocity (AGV).

The continued approval for the indication is contingent upon verification and description of clinical benefit in confirmatory studies to determine final adult height, to which the company is intending to use the ongoing open-label extension studies in comparison to available natural history.

Agent

Achondroplasia is the most common form of dwarfism, with the average height of an adult at approximately 4 feet. These patients have a genetic mutation that causes overactivation of fibroblast growth factor receptor 3, which generally prevents normal bone growth.

Vosoritide then binds to the natriuretic peptide receptor-B that reduces the growth regulation gene’s activity and stimulates bone growth.

Its approval was based on outcomes of the safety and efficacy of Vosoritide in improvement of growth were evaluated through a year-long, double-blind, placebo-controlled phase 3 study. A total of 121 children aged 5 - 14.9 years with achondroplasia were randomized to either vosoritide injection under the skin or placebo.

Data show the baseline mean AGV was 4.06 cm/year in the placebo group and 4.26 cm/year int the vosoritide group. Then, 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, at a statistically significant improvement in AGV of 1.57 cm/year with vosoritide. During the open-label extension of 58 patients, the improvement in AGV was maintained at 2 years of follow-up.

Common side effects included injection site reaction, vomiting, and decreased blood pressure. The label lists decreased blood pressure as both a warning and precaution, noting a potential serious side effect. A total of 8 (13%) of 60 patients treated with vosoritide had 11 events of transient decreases in blood pressure, compared to 3 (5%) of 61 patients on placebo.

Reaction

The approval was met with positive reactions, including Theresa Kehoe, MD, director of the Division of General Endocrinology in the FDA's Center for Drug Evaluation and Research, who said in a statement that the approval "fulfills 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," Kehoe said.

Additionally, Lynda Polgreen, M.D., an investigator in clinical trials for Voxzogo and an Investigator at The Lundquist Institute at Harbor-UCLA, noted the clinical importance of the agent’s approval.

"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 said.

Amer Haider, the co-founder of Growing Stronger, an organization that aims to improve quality of medical care for little people, applauded the decision and what it means for treatment going forward.

"We applaud the FDA for recognizing the urgent unmet medical need for this progressive condition,” Haider said. “As a parent of a child with achondroplasia, I see the availability of treatments that impact bone growth as an important step forward.”

The agent is expected to be available in the US in December.