THU165 PROPEL, PROPEL 2 And PROPEL OLE Studies Of Infigratinib In Children With Achondroplasia: Design And Status Of 3 Ongoing Trials

Disclosure: R. Savarirayan: Advisory Board Member; Self; Ascendis Pharma, BioMarin, QED Therapeutics, Sanofi. Consulting Fee; Self; BioMarin. Grant Recipient; Self; Ascendis Pharma, BioMarin, QED Therapeutics, Therachon. Research Investigator; Self; Ascendis Pharma, BioMarin, QED Therapeutics, Therachon. J. De Bergua: None. P. Arundel: None. H. McDevitt: None. V. Cormier-Daire: Advisory Board Member; Self; BioMarin. V. Saraff: None. M. Skae: None. B. Delgado: None. A. Leiva-Gea: None. M. Salcedo: None. J. Salles: None. M.P. Nicolino: None. M. Rossi: Advisory Board Member; Self; BioMarin. P. Kannu: Advisory Board Member; Self; Novartis, Ipsen. Grant Recipient; Self; CIHR. M. Bober: Advisory Board Member; Self; Biomarin. Consulting Fee; Self; Ascendis Pharma, BioMarin, Pfizer, QED Therapeutics. Grant Recipient; Self; Ascendis Pharma, BioMarin, Pfizer, QED Therapeutics. Research Investigator; Self; Ascendis Pharma, BioMarin, Pfizer, QED Therapeutics. J. Phillips III: None. H. Saal: Advisory Board Member; Self; Alexion. Grant Recipient; Self; Alexion, BioMarin, Pfizer, QED Therapeutics. Research Investigator; Self; Alexion, BioMarin, Pfizer, QED Therapeutics. P. Harmatz: Consulting Fee; Self; Audentes, Aeglea, Homology, JCR, Denali, Inventiva, Paradigm, Capsida, Chiesi, Avrobio. Grant Recipient; Self; BioMarin, Inventiva. Research Investigator; Self; BioMarin, Shire/Takeda, QED Therapeutics, RegenXbio, Denali, Ascendis, Amicus, Allievex, JCR, Orphazyme, Idorsia, Sangamo. C. Burren: Grant Recipient; Self; Amgen, Pfizer, QED Therapeutics. Research Investigator; Self; Amgen, Pfizer, QED Therapeutics. T. Candler: None. T. Cho: Employee; Self; QED Therapeutics. Stock Owner; Self; QED Therapeutics. E. Muslimova: Employee; Self; QED Therapeutics. Stock Owner; Self; QED Therapeutics. R. Weng: Employee; Self; QED Therapeutics. Stock Owner; Self; QED Therapeutics. D. Rogoff: Employee; Self; QED Therapeutics. Stock Owner; Self; QED Therapeutics. J. Hoover-Fong: Consulting Fee; Self; Pfizer/Therachon, BioMarin, QED Therapeutics, Sanofi, Ascendis Pharma. Grant Recipient; Self; Pfizer/Therachon, BioMarin, Ascendis Pharma. Research Investigator; Self; Pfizer/Therachon, BioMarin, Ascendis Pharma. M. Irving: Advisory Board Member; Self; Ascendis Pharma, BioMarin, QED Therapeutics, Sanofi, Therachon/Pfizer. Speaker; Self; BioMarin, QED Therapeutics. Background: Achondroplasia (ACH), the most common short-limbed skeletal dysplasia, is characterized by defective endochondral ossification resulting from gain-of-function mutations in the fibroblast growth factor receptor 3 (FGFR3) gene, a negative regulator of endochondral bone formation. Infigratinib is a selective, orally bioavailable FGFR1-3 tyrosine kinase inhibitor being investigated for the treatment of ACH in the observational and 2 interventional studies, as detailed below. Methods: PROPEL (NCT04035811) is a non-interventional clinical assessment study designed to characterize the natural history of ∼250 children 2.5 to <17 years of age with ACH over a 6−24-month period. Primary objective: collect baseline height velocity measurements in children who may participate in an interventional study with infigratinib. Primary endpoint: annualized growth velocity (AGV). Further objectives: collect other baseline growth measurements; evaluate exploratory biomarker indicators of growth; assess ACH-related medical events reported as medical history, or non-treatment adverse events (AEs), health-related quality of life, body pain, functional abilities and cognitive functions in children with ACH. PROPEL 2 (NCT04265651) is a phase 2, open-label study of infigratinib in children 3−11 years of age with ACH who completed ≥6 months of observation in PROPEL. This study includes dose-escalation (extended dose-finding treatment phase, n≥40), a pharmacokinetics sub-study (n≥18), and a dose-expansion phase (n≈20) to confirm the selected dose and provide evidence of efficacy. Primary endpoints: AEs; change from baseline in AGV; and infigratinib pharmacokinetics. Secondary endpoints: safety/tolerability of infigratinib; changes from baseline in anthropometric parameters. Exploratory outcomes: changes in quality of life (QoL) and other parameters of disease burden. PROPEL OLE (NCT05145010) is a phase 2, open-label extension study in ∼230 children who completed an interventional study with infigratinib and, potentially, in ≤50 infigratinib-naïve children. Primary objectives: safety, tolerability; and efficacy of long-term daily doses of infigratinib. Secondary objectives: changes in other indicators of growth/development, skeletal abnormalities, QoL/disease burden, and cognitive functions. Children may receive infigratinib until they reach final height. Summary: The PROPEL, PROPEL 2, and PROPEL OLE studies are ongoing. Together, they are intended to contribute to the understanding of the natural history of ACH, provide key evidence on the safety and efficacy of oral infigratinib, including QoL and skeletal changes in children with ACH, and inform the design of future studies in this setting. Presentation: Thursday, June 15, 2023