BridgeBio Pharma (NASDAQ:BBIO) shares climbed about 9% on Thursday after the biotech group unveiled positive Phase 3 topline results for its oral drug infigratinib in achondroplasia, marking what it said were the first statistically significant gains in body proportionality seen in the condition.
The late-stage PROPEL 3 study met its primary endpoint, showing that patients treated with infigratinib achieved superior improvements in annualized height velocity (AHV) versus placebo at 52 weeks. The company reported a mean treatment difference of +2.10 cm per year, with a least squares mean of +1.74 cm per year.
In a pre-specified exploratory subgroup analysis of children under eight — who accounted for more than half of trial participants — the therapy also delivered the first statistically significant improvement in body proportionality compared with placebo in achondroplasia. The least squares mean treatment difference was -0.05.
Safety data appeared favorable. The company said the treatment was well tolerated, with no drug-related serious adverse events or discontinuations. Three cases (4%) of hyperphosphatemia were recorded, all mild and temporary, and none required dose reductions or treatment interruption.
BridgeBio said it intends to file both a New Drug Application (NDA) in the U.S. and a Marketing Authorization Application (MAA) in Europe in the second half of 2026. Oral infigratinib is currently the only therapy in development for achondroplasia that has received Breakthrough Therapy Designation from the FDA.
Buoyed by the results, the company also plans to speed up development of the drug for hypochondroplasia, with enrollment already underway for the observational run-in phase of a separate Phase 3 trial.
Achondroplasia is a rare genetic disorder driven by overactivity of the FGFR3 pathway, leading to impaired bone growth and disproportionate short stature, particularly affecting limb length and overall body proportions.