Paquinimod is an immunomodulatory compound preventing S100A9 binding to TLR-4. It was studied in experimental osteoarthritis, in patients with mild active systemic lupus erythematosus and in systemic sclerosis patients. In January 2014, the US FDA granted orphan drug designation to paquinimod for the treatment of systemic scleroderma. The Orphan designation is implemented to promote the development of drugs that may provide significant benefit to patients suffering from rare diseases identified as life threatening or chronically debilitating. The further development of paquinimod for systemic lupus erythematosus and rheumatoid arthritis was discontinued.