Sarcoidosis is an inflammatory disease of unknown cause, characterised by the formation of granulomas (clumps of inflammatory cells) in one or more organs in the body. Sarcoidosis affects people of all ages, and is commonly first diagnosed between the ages of 20 and 39 years. Approximately 1.2 million people worldwide currently live with sarcoidosis. Sarcoidosis can occur in any organ in the body but affects the lungs in over 90% of patients. Sarcoidosis in the lungs is called pulmonary sarcoidosis. The prognosis for patients with pulmonary sarcoidosis ranges from benign and resolving without treatment to chronic, progressive disease. Chronic, unresolved inflammation in the lungs may result in scarring (fibrosis) that permanently damages the lung tissue and can lead to lung failure and death. The current standard of care for patients with pulmonary sarcoidosis involves treatment with oralsteroids and other immunosuppressive therapies, which have limited evidence of effectiveness and can cause serious long-term side effects. There is a need for new treatment options for sarcoidosis patients with progressive disease.