A Study of Andecaliximab in Participants With Fibrodysplasia Ossificans Progressiva (FOP)

The ASH-FOP-201 Study consists of 2 parts: Part 1 is a Lead-in Study to assess safety, PK/PD and preliminary efficacy; Part 2 is the Main Study, a Phase 2/3 randomized, double-blind, placebo-controlled trial. Part 1 is composed of Part 1a, a Na18F positron emission tomography (PET)/computed tomography, less head (CT) Study in up to 6 participants age ≥ 15 years, and Part 1b, a flare-up Study in up to 6 participants ≥ 12 years of age. Participants enrolled in Part 1 will be randomized to one of two dose levels for 13 weeks. Participants in Part 2 will be randomized to one of two dose levels of drug vs. placebo during the 52 week trial. All participants in Part 1 or Part2 will receive study drug in the extension period of the trial.