Infigratinib Shows Broader Clinical Benefits Beyond Growth in Children with Achondroplasia

BridgeBio Pharma reported new Phase 3 PROPEL 3 (NCT06164951) analyses showing that oral investigational infigratinib may improve or stabilize several medical complications associated with achondroplasia beyond its established effect on growth. The findings, presented at the 2026 Annual Meeting of the European Society for Paediatric Endocrinology (ESPE), included trends in sleep apnea, otitis media, body composition, and longer-term body proportionality.

Sleep Apnea Measures Remained More Stable

At 52 weeks, the mean total apnea-hypopnea index (AHI) increased 10.4% from baseline in children receiving oral infigratinib, compared with a 49.2% increase with placebo. Among children younger than 8 years, mean AHI remained unchanged with infigratinib, while increasing 63.2% with placebo.

Sleep-disordered breathing is a clinically important complication of achondroplasia. The new findings suggest that reducing excessive FGFR3 signaling may influence complications linked to skeletal anatomy and airway function, although these exploratory analyses do not establish a definitive treatment effect on sleep apnea.

The treatment group also had a lower estimated annualized rate of otitis media. Rates were 38% lower versus placebo overall and 47% lower among children younger than 8 years. Recurrent middle-ear disease can contribute to hearing and speech-development problems in children with achondroplasia.

Body Composition and Proportionality

PROPEL 3 also showed favorable trends in body composition. Mean BMI increased by 0.50 kg/m² with infigratinib versus 0.93 kg/m² with placebo. Infigratinib was associated with a greater increase in lean body mass, 1.77 kg versus 1.58 kg, while increases in body fat mass and visceral fat volume were smaller than with placebo.

Longer-term PROPEL data extended these findings. Children treated for up to three years showed a +0.92 standard deviation change from baseline in height Z-score and a -0.15 change in the upper-to-lower body segment ratio. The treatment remained well tolerated, with no new safety signals identified.

Targeting the FGFR3 Pathway

Achondroplasia results from an activating variant in FGFR3, which drives excessive downstream MAPK and STAT1 signaling and disrupts growth-plate development. Infigratinib is an oral small-molecule FGFR3 inhibitor that reduces this overactive signaling and thereby promotes bone growth.

The new analyses build on the primary PROPEL 3 findings published in the New England Journal of Medicine. In that study, infigratinib improved annualized height velocity by 2.10 cm per year versus placebo (p<0.0001) and produced a statistically significant improvement in body proportionality among children younger than 8 years.

FDA Filing Advances Toward Potential 2027 Launch

BridgeBio has submitted a New Drug Application to the U.S. FDA for oral infigratinib in achondroplasia and expects a potential U.S. launch in mid-2027. The company plans to submit a Marketing Authorization Application to the European Medicines Agency in the fourth quarter of 2026.

Infigratinib has received FDA Breakthrough Therapy, Orphan Drug, Fast Track, and Rare Pediatric Disease designations. If approved, BridgeBio may qualify for a Priority Review Voucher.

The development program is also extending into younger children through the ongoing Phase 2/2b PROPEL Infant & Toddler study in children younger than 3 years.

Reference

Oral Infigratinib Shows Meaningful Benefits Beyond Growth Within 52 Weeks in Children with Achondroplasia in the Phase 3 PROPEL 3 Trial, BridgeBio, 09 September 2026