BridgeBio Pharma will expand study of its experimental drug for a common form of dwarfism after initial clinical trial results suggested treatment could help children with the condition grow faster.
Among study participants given the highest dose of BridgeBio’s drug, the average annualized increase in “height velocity” was 1.5 centimeters a year over baseline, the company said Tuesday. Lower doses didn’t yield as sizable an increase and response to treatment was mixed, however.
Following discussions with the Food and Drug Administration, BridgeBio will now expand study enrollment to test an even higher dose. Full study results are expected to be available next year.
The children in BridgeBio’s study all have achondroplasia, a genetic condition that causes short stature and disproportionate growth. Approximately 55,000 people in the U.S. and Europe have the condition, according to BridgeBio, including 13,000 children and teenagers whose growth plates are open and could still grow.
Achondroplasia stems from a mutation in a gene called fibroblast growth factor receptor, or FGFR3. The mutation leads to overactive gene expression, which in turn prevents normal bone growth. BridgeBio’s drug, called infigratinib, is designed to block FGFR3.
The company’s study was small, with only 11 children 5 years of age or older treated with the highest, most effective dose. Participants were followed for a median of about 27 weeks, BridgeBio said. Further follow-up through one year will be important in determining whether the benefit holds up over time, analysts from Mizuho Securities and SVB Securities wrote in notes to clients.
Still, the data appear to roughly match the height gains reported by BioMarin Pharmaceutical in a Phase 3 study of its approved achondroplasia treatment Voxzogo.
On safety, BridgeBio reported no serious side effects related to treatment across all 62 evaluated participants. There was one case of mild elevations in phosphate levels, which led to a reduction in dose but later resolved. There were no bone-related adverse reactions, BridgeBio said.
“This product profile positions infigratinib to compete effectively with competitor [BioMarin],” wrote SVB Securities analyst Mani Foroohar, citing the drug’s oral administration and recent doctor surveys in a July 26 note to clients. Voxzogo, which has been on the market since late last year, is given via a subcutaneous injection.
Shares in BridgeBio fell by more than 10% during Tuesday morning trading, outstripping a 1% decline in a broader biotechnology sector index.