By VETTAPHARMA reporter: BridgeBio Pharma, Inc. announced positive topline results from its global Phase 3 PROPEL 3 study of oral infigratinib in children living with achondroplasia, marking the first time a therapy in this condition demonstrated statistically significant improvements in body proportionality in addition to robust gains in growth velocity.
Achondroplasia is a genetic condition that affects how bones grow, leading to a common form of dwarfism. People with achondroplasia typically have shorter arms and legs compared to their torso, resulting in disproportionate short stature. It is caused by a change in a gene that affects bone development, especially in the long bones of the arms and legs. While intelligence is usually unaffected, individuals may face medical challenges such as ear infections, breathing problems, spinal issues, and joint pain. The condition is present from birth and varies in severity from person to person.The PROPEL 3 trial successfully met its primary endpoint at Week 52, showing that children treated with infigratinib achieved a superior change from baseline in annualized height velocity (AHV) compared with placebo. The least squares (LS) mean treatment difference was +1.74 cm per year (p < 0.0001), with a mean treatment difference of +2.10 cm per year against placebo — outcomes typically regarded as highly statistically significant in pediatric growth studies.
Importantly, the study also achieved a key secondary endpoint — the first statistically significant improvement in body proportionality for achondroplasia observed in a randomized trial. In a prespecified exploratory analysis of children younger than 8 — who accounted for more than half of participants — infigratinib showed an LS mean decrease of –0.05 (p < 0.05) compared with placebo, suggesting a meaningful shift toward more typical limb-to-trunk proportions.
Another key outcome, the height Z-score change relative to an achondroplasia reference population, was also superior to placebo at Week 52. The LS mean improvement on the infigratinib arm was +0.41 standard deviations (SD) (p < 0.0001), the largest observed difference in any randomized achondroplasia trial.
Infigratinib was well tolerated throughout the study, with no discontinuations or serious adverse events related to the study drug. Reported safety events included three cases (4 %) of mild and transient hyperphosphatemia that did not require dose reductions or discontinuations, and no adverse events associated with FGFR1/2 inhibition or with CNP analogues.
BridgeBio plans to pursue regulatory submissions later in 2026, with New Drug Application (NDA) and Marketing Authorization Application (MAA) filings targeted in the second half of the year for achondroplasia based on these results. The company also intends to accelerate development of infigratinib in hypochondroplasia, a related skeletal dysplasia, and is enrolling participants in its Phase 3 observational run-in study.
Achondroplasia is the most common cause of disproportionate short stature, affecting tens of thousands of children globally and often leading to complications such as pain, limited mobility, and neurological issues. The PROPEL 3 results — particularly the body proportionality findings — underscore the potential of an oral, targeted therapy to address both growth and shape aspects of this genetic condition.
Source credit:
- BridgeBio Pharma, Inc. (2026, February 12). BridgeBio reports positive Phase 3 topline results for oral infigratinib with the first statistically significant improvements in body proportionality in achondroplasia. Click here
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