A Randomized, Placebo-controlled Study to Assess the Safety, Tolerability, Pharmacokinetics, and Effects on Heterotopic Bone Formation of REGN2477 in Patients With Fibrodysplasia Ossificans Progressiva

Detailed Summary

This is a three period study design consisting of a 6-month, randomized, double-blind placebo-controlled treatment (period 1) followed by a 6-month, open-label treatment (period 2) and a follow-up treatment period (period 3). Primary safety objective of the study is to assess the safety and tolerability of REGN2477 in male and female patients with fibrodysplasia ossificans progressiva (FOP). Primary efficacy objective of the study is to assess the effect of REGN2477 versus placebo on the change from baseline in heterotopic ossification (HO) in patients with FOP, as determined by 18-NaF uptake in HO lesions by positron emission tomography (PET) and in total volume of HO lesions by computed tomography (CT). Key Secondary objectives are: * To compare the effect of REGN2477 versus placebo on pain due to FOP, as measured by the area under the curve (AUC) for pain based on daily pain numeric rating scale (NRS) scores * To assess the effect of REGN2477 versus placebo on the change from baseline in HO, as determined by the number of new HO lesions identified by 18F-NaF PET or by CT * To assess the effect of REGN2477 versus placebo on the change from baseline in 18F-NaF standardized uptake value maximum (SUVmax) of individual active HO site(s) by PET * To assess the effect of REGN2477, between week 28 and week 56, on the number, activity, and volume of HO lesions identified by 18F-NaF PET or by CT in patients who switch from placebo to REGN2477 at week 28 versus the same patients between baseline and week 28 * To assess the effect of REGN2477 versus placebo on the change from baseline in biochemical markers of bone formation * To characterize the concentrations of total activin A at baseline and over time following the first dose of study drug * To characterize the concentration-time profile (pharmacokinetics \[PK\]) of REGN2477 in patients with FOP * To assess the immunogenicity of REGN2477

Study Details

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Interventions