FDA OKs First Drug for Most Common Form of Dwarfism

The FDA granted accelerated approval to the first drug to spur growth in kids with the most common form of dwarfism, the agency announced on Friday.

Vosoritide (Voxzogo), a once-daily injectable treatment, is indicated for children 5 years and older with achondroplasia and who still have open growth plates — in other words, these children still have the potential to grow.

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

The drug’s efficacy was demonstrated in a year-long phase III study of 121 patients with achondroplasia who had open epiphyses. Compared with patients on placebo, those treated with 15 mg/kg of subcutaneous vosoritide grew an average 1.57 cm/year taller. In an open-label extension study after the 52-week double-blind study, patients on vosoritide maintained improvement in annualized growth velocity.

“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,” said investigator Lynda Polgreen, MD, of David Geffen School of Medicine at UCLA, in a statement from drugmaker BioMarin Pharmaceutical’s announcement.

Not all were pleased with the approval though, with Little People of America calling the focus on growth velocity “a pharmaceutical solution for a societal problem.”

“As medical science moves forward, we will continue to inform researchers about the value of dwarf pride and its contributions to human biological, social, and cultural diversity,” the advocacy group said in a statement, calling for a shift in research priorities away from just height and instead towards reducing other medical issues individuals with achondroplasia face like spinal stenosis and sleep apnea.

Kicking off the start of a new drug class, vosoritide is a C-type natriuretic peptide analog that promotes bone growth by acting as a positive regulator of the signaling pathway downstream of the fibroblast growth factor receptor 3 gene. In achondroplasia, endochondral bone growth is inhibited by a gain of function mutation in this gene.

The injection is recommended to be administered at the same time every day by a caregiver after a healthcare provider deems the caregiver able to handle the process. Dosing is based on a patient’s body weight and can be adjusted based on changes in weight.

In the phase III trial, the most common adverse events included injection site reactions, vomiting, joint pain, decreased blood pressure, gastroenteritis, diarrhea, dizziness, ear pain, influenza, fatigue, seasonal allergy, and dry skin.

Under conditions of the drug’s accelerated approval, a post-marketing study will be required to assess final adult height in treated patients.

BioMarin said vosoritide is expected to hit U.S. shelves by mid- to late-December. The drug was approved in Europe in August.