BridgeBio Pharma (NASDAQ:BBIO) detailed positive Phase 3 results from its PROPEL-3 clinical trial evaluating oral infigratinib for children with achondroplasia, describing what executives called consistent efficacy across key endpoints and a well-tolerated safety profile. Company leaders also outlined plans for regulatory submissions, additional studies in related conditions, and early commercialization preparations.
PROPEL-3 trial design and population
Chief Medical Officer Dr. Daniela Rogoff said PROPEL-3 was a double-blind, placebo-controlled Phase 3 trial assessing the efficacy and safety of once-daily oral infigratinib in children ages 3 to under 18 with achondroplasia and remaining growth potential. Children were required to have completed at least six months in an observational study before entering PROPEL-3 and were randomized 2:1 to infigratinib or placebo for 52 weeks, with an option to roll into a long-term extension study (PROPEL OLE).
Efficacy results: growth, Z-score, and proportionality
Management emphasized that the trial met its primary endpoint and showed gains across secondary measures. On the primary endpoint—change from baseline in annualized height velocity (AHV) versus placebo—BridgeBio reported both an unadjusted and a least-squares (LS) mean difference:
- Mean difference in change from baseline AHV: 2.1 cm/year vs placebo (p<0.0001), as described by Rogoff.
- LS mean difference in change from baseline AHV: 1.74 cm/year vs placebo (p<0.0001).
Executives said the improvement was consistent across age subgroups and described the effect size as the largest reported in a randomized controlled achondroplasia trial. Rogoff added that children receiving infigratinib increased AHV to around 6 cm/year and maintained that rate, while placebo participants continued at typical achondroplasia growth rates. The company cited an LS mean AHV of 5.96 cm/year on treatment at week 52, calling it the highest reported to date.
On height Z-score (calculated using achondroplasia reference data), the company reported an LS mean change from baseline of +0.41 in the treatment arm and an LS mean difference versus placebo of +0.32 (p<0.0001). Executives highlighted both the magnitude of the change and the speed of separation from placebo over time.
BridgeBio also highlighted results related to body proportionality, measured by upper-to-lower body segment ratio. In the overall population, the company reported a favorable trend with an LS mean difference of -0.02 versus placebo. In a pre-specified exploratory analysis in children ages 3 to 8—nearly 60% of trial participants—BridgeBio reported a statistically significant LS mean difference of -0.05 versus placebo, which executives framed as the first statistically significant proportionality result in a 52-week placebo-controlled achondroplasia study. During Q&A, Rogoff said the proportionality signal could suggest potential benefits in functionality and activities of daily living, while management said it was “too early” to predict label language but expressed optimism.
Safety findings and management commentary
BridgeBio said infigratinib was well-tolerated, with treatment-emergent adverse events balanced between arms and mostly grade 1 or 2. Executives reported no serious adverse events (SAEs) related to the study drug and no discontinuations related to the study drug.
Management highlighted three cases of hyperphosphatemia, which it said were mild, asymptomatic, and transient, resolving without dose reduction or discontinuation. Rogoff said the three cases involved boys around 13 years old and that phosphorus elevations were small (no more than 0.4 mg/dL above baseline), which she described as within expected variability. She also said the mean phosphorus levels remained comparable to placebo and within normal ranges over time, and the company reported no adverse events associated with FGFR1/FGFR2 inhibition, such as corneal or retinal events.
In response to a question about central nervous system (CNS) safety concerns, Rogoff characterized such claims as unfounded and said they were based on neonatal knockout mouse model experiments that she said were not relevant to infigratinib use in children at the studied dose. She cited clinical experience from earlier studies, including data “up to five years in nearly 200 kids,” as supportive of the safety profile described on the call.
Next steps: filings, lifecycle studies, and commercial preparation
Rogoff said BridgeBio is preparing regulatory submissions and plans to submit a new drug application to the FDA and a marketing authorization application to the EMA in the second half of 2026. Management also said it expects to present more detailed results at future medical and patient advocacy conferences.
Executives described additional development plans for a broader FGFR3-driven portfolio, including:
- An ongoing trial in infants and toddlers with achondroplasia that the company said it believes will be “registration-enabling” for that age group.
- Accelerated work in hypochondroplasia, with enrollment underway for an observational run-in ahead of a Phase 3 trial.
- Exploration of potential effects on spinal health in adults with achondroplasia, based on the mechanistic role of FGFR3 in spinal tissue.
- Planning for studies in Turner syndrome and SHOX deficiency, where management said evidence suggests FGFR3 overactivity may play a role.
Chief Commercial Officer Matt Outen said BridgeBio plans to commercialize infigratinib globally “with the exception of Japan,” where the company has an established partnership. He described the achondroplasia treatment market as concentrated and suggested a smaller, targeted sales force could cover the U.S. effectively. Outen also announced that Aaron McIlwain joined BridgeBio from Ionis Pharmaceuticals as Senior Vice President of Sales and Marketing.
During Q&A, Outen said the skeletal dysplasia market is about $5 billion including achondroplasia. He also referenced prior market research suggesting injection burden is a major concern for families, and said the company is updating its research following the new data. Management said it believes an oral option could expand uptake among treatment-naïve and switching patients, emphasizing “freedom from injections” as a key differentiator.
About BridgeBio Pharma (NASDAQ:BBIO)
BridgeBio Pharma, Inc is a clinical-stage biopharmaceutical company headquartered in Palo Alto, California. Founded in 2015 by Neil Kumar, the company is dedicated to discovering, developing and delivering transformative medicines for patients with genetic diseases and cancers. BridgeBio operates an integrated model that spans target identification, preclinical research, clinical development and commercialization, aiming to streamline the process from bench to bedside.
BridgeBio’s pipeline comprises multiple therapeutic modalities, including small molecules, biologics and genetic therapies.
