At a Glance
- PROPEL 3 met primary endpoint with +1.74 cm/year height velocity gain over placebo (p<0.0001).
- Achieved record 5.96 cm/year absolute AHV; largest Z-score (+0.41 SD) and proportionality improvements.
- Well-tolerated no discontinuations, serious AEs, or injections needed.
- H2 2026 NDA/MAA filings; expanding to infants and hypochondroplasia trials.
Written By: Pharmacally Medical News Desk
BridgeBio Pharma has reported positive topline results from the Phase 3 PROPEL 3 trial, demonstrating that oral infigratinib significantly improved growth velocity in children with achondroplasia. The therapy is designed to directly target FGFR3 signaling, the underlying molecular driver of the condition.
Infigratinib is a selective oral FGFR3 inhibitor developed to target the dysregulated FGFR3 signaling that drives achondroplasia. By reducing excessive receptor activity in growth plate chondrocytes, the therapy aims to restore more balanced growth signaling, contributing to increased growth velocity and improvements in body proportionality without the need for injections.
Daniela Rogoff, MD, Chief Medical Officer, Skeletal Dysplasia at BridgeBio, highlighted the potential clinical relevance of an oral, non-injectable treatment option for children living with achondroplasia.
Trial Design and Primary Endpoint
PROPEL 3 (NCT06164951) evaluated children aged 3 to under 18 years with open growth plates in a global, one-year, randomized, double-blind, placebo-controlled study using a 2:1 randomization ratio.
The trial met its primary endpoint, demonstrating a statistically significant improvement in annualized height velocity (AHV) at Week 52. Infigratinib-treated participants showed least squares mean difference of +1.74 cm/year versus placebo (p<0.0001). The observed mean difference was +2.10 cm/year, indicating a clinically meaningful increase in linear growth over the treatment period.
Key Secondary Endpoints
At Week 52, children receiving infigratinib achieved least squares mean AHV of 5.96 cm/year, compared with 4.22 cm/year in the placebo group, representing one of the highest growth rates reported in randomized achondroplasia trials.
Height Z-score improvements were also statistically significant, with least squares mean treatment difference of +0.32 standard deviations (p<0.0001). Participants receiving therapy demonstrated a +0.41 standard deviation gain, among the largest Z-score improvements reported to date.
In a pre-specified exploratory analysis of children younger than 8 years, infigratinib demonstrated a statistically significant improvement in body proportionality compared with placebo. This was reflected by a reduction in the upper-to-lower body segment ratio (least squares mean decrease of -0.05, p<0.05). A similar reduction (-0.05) was observed in the overall study population.
Safety Profile
Infigratinib was generally well tolerated. No treatment-related discontinuations or treatment-related serious adverse events were reported.
Hyperphosphatemia occurred in three participants (4%), with all cases classified as mild, transient, and asymptomatic, resolving without intervention. No safety signals commonly associated with broader FGFR inhibition were observed.
Ravi Savarirayan, MD, global lead investigator, noted that targeted FGFR3 modulation may influence clinical outcomes beyond linear growth, while emphasizing the convenience of oral administration.
Michael Hughes, Chair of the Biotech Industry Liaison Committee at Little People of America (LPA) the leading advocacy group for the dwarfism community called BridgeBio’s PROPEL 3 results a milestone in achondroplasia research.
BridgeBio plans regulatory discussions for NDA/MAA filings in H2 2026, supported by infigratinib’s FDA Breakthrough Therapy, Orphan Drug (FDA/EMA), Fast Track, and Rare Pediatric Disease designations.
The company is accelerating development for hypochondroplasia through the observational ACCEL lead-in study (NCT06410976) and Phase 2/3 ACCEL 2/3 trial (NCT06873035), alongside the ongoing PROPEL Infant & Toddler trial (NCT07169279) for newborns to under-3-year-olds with achondroplasia demonstrating commitment to addressing unmet needs across age groups and related skeletal dysplasia like hypochondroplasia.
About Achondroplasia
Achondroplasia is an FGFR3-driven skeletal dysplasia and the most common cause of disproportionate short stature. The condition is associated with complications including sleep apnea, recurrent ear disease, kyphosis, and spinal stenosis, which may impact long-term health and quality of life.
Reference
BridgeBio Reports Positive Phase 3 Topline Results for Oral Infigratinib with the First Statistically Significant Improvements in Body Proportionality in Achondroplasia, 12 February 2026, BridgeBio Pharma Inc. – BridgeBio Reports Positive Phase 3 Topline Results for Oral Infigratinib with the First Statistically Significant Improvements in Body Proportionality in Achondroplasia
A Study to Evaluate the Efficacy and Safety of Infigratinib in Children and Adolescents with Achondroplasia (PROPEL3), ClinicalTrials.gov ID NCT06164951, https://clinicaltrials.gov/study/NCT06164951