BridgeBio's Achondroplasia Pill Shows Benefits Beyond Growth in Phase 3 Trial
BridgeBio Pharma (BBIO) has reported that its experimental oral treatment for achondroplasia demonstrated meaningful benefits beyond height gain in a Phase 3 trial, with data showing improvements in sleep apnea and ear infection rates that could strengthen its case for regulatory approval.
The new exploratory results from the PROPEL 3 study, presented at the European Society for Paediatric Endocrinology meeting in Marseille, showed that children receiving oral infigratinib for 52 weeks experienced far more modest worsening of sleep apnea than those on placebo. The mean apnea-hypopnea index — a standard measure of sleep-disordered breathing — rose by just 10.4 per cent in the treated group, against a 49.2 per cent increase among those on placebo. In children under eight, the treated group saw no change, while the placebo group's index rose by 63.2 per cent.
The drug also reduced the rate of otitis media — recurring middle ear infections that can impair hearing and speech development — by 38 per cent compared to placebo, rising to 47 per cent in younger children. Treated patients additionally showed a more favorable body composition profile, with smaller gains in body fat and visceral fat volume compared to the placebo group.
"Growth is only one part of the picture of this medically complicated condition in which children experience disrupted sleep, recurring ear infections, or other health challenges," said Melita Irving of Guy's and St Thomas' NHS Foundation Trust in London. Irving pointed to three-year data from the broader PROPEL program showing sustained improvements in height and body proportionality, alongside a stable safety profile with no new signals identified.
Those longer-term findings showed a change from baseline in height Z-score of +0.92 standard deviations at Year 3 and an improvement in the upper-to-lower body segment ratio of -0.15 — metrics that reflect the disproportionate limb growth characteristic of the condition. The primary endpoint results, previously published in the New England Journal of Medicine, had already shown a 2.10 cm per year improvement in annualized height velocity versus placebo.
Achondroplasia, the most common cause of disproportionate short stature, affects around 55,000 people in the United States and European Union combined. The condition is caused by an overactivating variant in the FGFR3 gene and can be associated with serious complications including spinal stenosis and obstructive sleep apnea. Oral infigratinib works by inhibiting FGFR3 signaling, targeting the condition at its molecular source.
BridgeBio submitted a new drug application to the US Food and Drug Administration for the drug in achondroplasia and is targeting a US commercial launch in mid-2027. The company plans to file a marketing authorization application with the European Medicines Agency in the fourth quarter of 2026. The drug holds Breakthrough Therapy, Orphan Drug, Fast Track, and Rare Pediatric Disease designations from the FDA — the last of which could entitle BridgeBio to a Priority Review Voucher upon approval.