FDA Clears Abbisko's FGFR Inhibitor for Achondroplasia as BridgeBio Reports Phase 3 Success
The FDA has cleared Abbisko Therapeutics' IND application for ABSK061, an oral FGFR2/3 inhibitor for achondroplasia, while BridgeBio reports positive Phase 3 results for its oral infigratinib in the same condition. Both companies are advancing oral therapies targeting FGFR3 overactivity in this genetic growth disorder.
The U.S. Food and Drug Administration has cleared the Investigational New Drug application for ABSK061, a highly selective small-molecule FGFR2/3 inhibitor, for the treatment of children with achondroplasia. This regulatory clearance comes as BridgeBio Pharma announces positive topline results from PROPEL 3, its global Phase 3 pivotal study of oral infigratinib in children with the same genetic condition.
ABSK061 is currently being evaluated in a Phase II clinical trial for achondroplasia, and in December 2025, the study dosed its first patient in China. Preliminary data are expected to be reported in the second half of 2026. As an important part in the global development strategy for ABSK061, Abbisko plans to enroll US patients into the Phase II study to further evaluate safety, tolerability, and efficacy of ABSK061 for the treatment of achondroplasia.
BridgeBio's PROPEL 3 was a one-year, global, 2:1 randomized, double-blind, placebo-controlled trial evaluating children aged 3 to <18 with open growth plates. In the broadest age range studied to date, oral infigratinib has demonstrated the highest and most significant improvement in annualized growth velocity, along with the first statistically significant improvement in body proportionality, in children aged 3 to 8 years, reported for any therapy approved or in development for this condition. The drug-related discontinuations or serious adverse events were reported, and side effects were mild and transient.
Achondroplasia is a rare autosomal genetic disorder that causes severe growth and developmental impairments. Research has shown that the pathogenesis of achondroplasia is driven by aberrant activation of the fibroblast Growth Factor Receptor 3 (FGFR3) caused by FGFR3 gene mutations, which suppress normal endochondral ossification. Targeted inhibitors offer the potential to deliver more precise and effective treatment options for achondroplasia patients.
ABSK061, independently developed by Abbisko Therapeutics, is a highly potent and selective small-molecule FGFR2/3 inhibitor. It has demonstrated robust target inhibitory activity, favorable pharmacokinetic properties, and a promising safety profile in preclinical studies. Its oral administration offers significant advantages in terms of convenience and treatment compliance—particularly for pediatric patients—and positions ABSK061 as a potentially valuable therapeutic candidate for children and adolescents with achondroplasia.
BridgeBio's CEO pointed to the company's "last three phase threes," citing positive Phase 3 readouts in ADH1, LGMD2I, and achondroplasia, which he said "all met or beat" expectations. For achondroplasia specifically, the company referenced prior market research suggesting potential preference share of 65%, while noting some key opinion leaders have suggested higher. Current market penetration is roughly 25%, and market research indicates about 35% of U.S. patients may be needle-phobic, framing the oral option as a potential driver to expand the addressable market and take share based on efficacy, safety, and convenience.