Fibrodysplasia Ossificans Progressiva (FOP)

This Phase 2, Randomized, Double-Blind, Placebo-Controlled Study is intended to evaluate the Efficacy, Safety, and Tolerability and PK of INCB000928 administered to participants with a clinical diagnosis of fibrodysplasia ossificans progressiva (FOP).

This study is researching an experimental drug called garetosmab, referred to as "study drug". The study is focused on children and adolescent participants with FOP. The aim of the study is to see how safe, tolerable, and effective the study drug is. The study is looking at several other research questions, including: * What side effects may happen from taking the study drug * How much study drug is in the blood at different times * Whether the body makes antibodies against the study drug (which could make the study drug less effective or could lead to side effects)

The Fibrodysplasia Ossificans Progressiva (FOP) Registry is a global, non-interventional, voluntary database that captures demographic and disease data directly from FOP patients and their caregivers via a secure, web-based patient portal. A physician portal (in development) will allow physicians to enter clinical data about their patients. The objectives are to organize the international FOP community for participation in clinical trials; to enable FOP patients worldwide to report data in a shared forum; to improve the collective understanding of FOP natural history; and to advance the understanding of FOP treatment outcomes.

This is an observational pre-post study to observe if the off label use of anti-IL1 therapies, such as anakinra or canakinumab, can block ACVR1-induced flare activity and heterotopic ossification in FOP. It will also generate key tools and preliminary data that are needed to design a future Phase II study. This study specifically focuses on patients with severe FOP who are being considered by their medical team for rescue therapy with anti-IL1 therapy. Preliminary data suggests patients experience significant decreases in flare frequency when taking anti-IL1 therapy, but other measures of efficacy remain unassessed, such as changes in heterotopic ossification formation, changes in pain medication use, and changes in functionality.