BridgeBio's Infigratinib Succeeds in Phase 3 Achondroplasia Trial, Plans 2026 Regulatory Filing

BridgeBio Pharma announced on February 12, 2026, that its oral therapy infigratinib met the primary endpoint in the global Phase 3 PROPEL 3 trial for children with achondroplasia, the most common form of skeletal dysplasia leading to disproportionate short-limb dwarfism. The company plans to seek regulatory approval in the U.S. and Europe in the second half of 2026.

The randomized, double-blinded, placebo-controlled PROPEL 3 trial evaluated infigratinib in approximately 110 children with achondroplasia aged 3 to less than 18 years with open growth plates. Participants were randomly assigned 2:1 to receive infigratinib 0.25mg/kg/day or placebo.

The trial successfully met its primary endpoint of change from baseline in annualized height velocity (AHV) at week 52, demonstrating superiority to placebo with a mean treatment difference of +2.10 cm/year and an LS mean treatment difference of +1.74 cm/year (p<0.0001).

For the secondary endpoint of absolute AHV at week 52, infigratinib showed significant improvement compared to placebo, with the infigratinib arm achieving the highest LS mean absolute AHV reported to date in a randomized trial in achondroplasia at 5.96 cm/year versus 4.22 cm/year on placebo.

Change from baseline in height Z-score (achondroplasia reference population) was superior to placebo, with an LS mean treatment difference of +0.32 SD (p<0.0001), the largest difference observed in a randomized trial in achondroplasia. The LS mean change from baseline on the treatment arm was +0.41 SD, the largest improvement observed on a treatment arm in a randomized trial for achondroplasia.

In a pre-specified exploratory analysis of children younger than 8 years (more than 50% of the participants), oral infigratinib became the first therapeutic option to show statistical significance against placebo in a randomized trial for achondroplasia on the key secondary endpoint of change from baseline in upper-to-lower body proportionality at week 52, demonstrating an LS mean decrease of -0.05 against placebo (p<0.05). In the overall population, infigratinib achieved an LS mean decrease of -0.05, the largest reduction observed in a treatment arm in a randomized achondroplasia trial, with a favorable LS treatment difference of -0.02 versus placebo at week 52 (p=0.1849).

Infigratinib was well-tolerated, with no discontinuations related to the study drug, and no serious adverse events related to the study drug were observed. Three cases (4%) of hyperphosphatemia were reported, all considered mild and transient with not a single case requiring either dose reduction or discontinuation. No adverse events associated with inhibition of FGFR1 or 2 (e.g., retinal or corneal) or events synonymous with C-type natriuretic peptide (CNP) analogues were observed.

BridgeBio intends to meet with regulatory authorities to discuss plans for submission of a New Drug Application (NDA) and Marketing Authorization Application (MAA) for infigratinib in the second half of 2026 to support approval. Infigratinib has received Breakthrough Therapy Designation from the FDA for achondroplasia, as well as Orphan Drug Designation from both the FDA and EMA, and Fast Track designation. It is the only therapeutic option in development for achondroplasia to have Breakthrough Therapy Designation from the FDA.

Given the strength of these data, BridgeBio plans to accelerate the development of oral infigratinib in hypochondroplasia, a milder form of achondroplasia with less severe growth issues, and is enrolling participants in the observational run-in for the Phase 3 trial. The company also has an ongoing clinical trial of infigratinib for newborns to three-year-old age groups in achondroplasia in the PROPEL Infant and Toddler trial.

If approved, infigratinib would be the first oral therapy for achondroplasia and would compete with BioMarin Pharmaceutical's Voxzogo (vosoritide), a daily injection that became the first FDA-approved drug for achondroplasia in November 2021. Voxzogo generated $654 million for BioMarin from January through September last year, accounting for more than a quarter of the company's revenue.

Ascendis Pharma's TransCon CNP (navepegritide), a once-weekly subcutaneous injection, is currently under FDA review with a PDUFA target action date of February 28, 2026.

Achondroplasia is a genetic condition driven by FGFR3 that affects more than stature alone, with consequences on physical functioning and independence. The condition affects about 55,000 people in the U.S. and the European Union. Infigratinib is an oral fibroblast growth factor receptor 1-3 blocker designed to directly inhibit FGFR3 protein phosphorylation, addressing the underlying cause of achondroplasia by targeting FGFR3 overactivity. The protein FGFR3 stalls bone growth by keeping cartilage cells from multiplying, maturing and turning into bone.

BridgeBio Pharma shares rose more than 5% to about $77 on Thursday following the announcement, with the stock hitting a high of $84.94 and nearing the upper end of its 52-week range of $28.33-$84.94.