Fibrodysplasia ossificans progressiva is a rare genetic disorder of the connective tissue characterized by heterotopic ossification, which is the abnormal development of bone in areas of the body where bone is not normally present, such as the ligaments, tendons, and skeletal muscles. 

The heterotopic ossification associated with fibrodysplasia ossificans progressiva usually starts in the first decade of life, presenting as inflammatory painful swellings of the soft tissue. As the disease progresses, heterotopic ossification severely restricts mobility and function in the joints and can eventually lead to breathing problems and cardiorespiratory failure if bone forms around the ribcage.

Sohonos (palovarotene) is the first FDA approved treatment for people with fibrodysplasia ossificans progressiva. Sohonos is a retinoic acid receptor agonist (RAR), with particular selectivity at the gamma subtype of RAR, which is an important regulator of skeletal development and ectopic bone in the retinoid signaling pathway. Sohonos works by mediating the interactions between the receptors, growth factors and proteins within the retinoid signaling pathway to reduce new abnormal bone formation.

Drugs used to treat Fibrodysplasia Ossificans Progressiva