Dive Brief:
- An experimental drug from BridgeBio Pharma helped accelerate growth in height among a dozen people with achondroplasia, the most common cause of disproportionate short stature.
- The results, from one group of a mid-stage clinical trial, showed that treatment with BridgeBio’s drug increased annualized height velocity by 2.5 centimeters after 18 months, compared to baseline. Treatment also improved body proportionality, BridgeBio said Tuesday.
- BridgeBio has already started a Phase 3 study of the drug, called infigratinib, and plans to complete enrollment by the end of the year. Infigratinib is seen by analysts on Wall Street as a potential competitor to Voxzogo, an achondroplasia treatment sold by BioMarin Pharmaceutical.
Dive Insight:
BridgeBio last detailed results from this study group, who received the highest tested dose of infigratinib, a little over one year ago. At the time, six month data showed an increase in annualized height velocity that easily surpassed the bar set by Voxzogo, drawing attention to infigratinib as a potentially more potent treatment. BridgeBio quickly moved ahead with a Phase 3 study based on those results.
Expectations had therefore ramped up for the company to disclose updated data from 12 and 18 months of follow-up. The increase in annualized height velocity of 2.5 centimeters reported Tuesday is below the 3.38 centimeters per year BridgeBio previously disclosed for six months, but above both what the company and Wall Street had anticipated.
The results were sustained between 12 months, when trial investigators recorded a 2.51-centimeter increase in annualized height velocity, and 18 months.
No serious side effects were reported, nor any that forced participants to discontinue treatment, BridgeBio said. There were also no instances of high phosphate levels, which was seen in prior testing of infigratinib in cancer.
Paul Matteis, an analyst at Stifel who has a “buy” rating on BioMarin shares, described BridgeBio’s drug as a “formidable competitor” to BioMarin’s Voxzogo, based on Tuesday’s data readout.
“Infigratinib clearly works and is likely to succeed in [Phase 3], though in our view it remains hard to say whether infigratinib is more efficacious than Voxzogo,” Matteis wrote in a client note. “Overall the drugs, as of now, are probably more similar on efficacy, and the bigger question of infigratinib is safety in [Phase 3].”
Matteis noted that the baseline growth velocity for participants in BridgeBio’s study was lower than in the main study of Voxzogo, which could potentially leave room for greater improvement.
Analysts at Mizuho Securities and Raymond James who cover BridgeBio were more bullish, viewing the company’s data as potentially superior to BioMarin’s.
Voxzogo treatment led to an increase in annualized height velocity of 1.57 centimeters over placebo at one year in the Phase 3 study that supported that drug’s approval.
Based on the data, BridgeBio said it is expanding development of infigratinib into hypochondroplasia, a related skeletal dysplasia that manifests in a wide range of symptoms.
There are an estimated 14,000 to 25,000 children in the U.S. and Europe who have either achondroplasia or hypochondroplasia and would be eligible for treatment, according to the company.