Pirfenidone as Treatment of Skin Fibrosis in Systemic Sclerosis

Inclusion Criteria: * Fulfill EULAR/ACR classification criteria (2013) for systemic sclerosis (SSc). * Subjects must have mRSS≥10 at screening stage * Subjects must have signs of fibrosis in their chest CT at screening stage * If a subject has received treatments before, it should be stable at least 3 months until screening and with no significant efficacy (ΔmRSS≤-2) Exclusion Criteria: * Subjects with other connective tissue diseases overlapping with SSc * Subjects with skin atrophy as the main cutaneous manifestation * Subjects with active digital ulcers or gangrene * Active severe SSc-driven renal disease or heart dysfunction at screening * Subjects with significant hematologic abnormalities * Abnormal liver function test at screening (ALT, AST or total bilirubin over 2 fold of upper normal level * Clinically significant active infection including ongoing and chronic infections * History of human immunodeficiency virus (HIV) * Confirmed Positive tests for hepatitis B or positive test for hepatitis C * Active tuberculosis * Live or attenuated vaccine within 4 weeks prior to screening * Subjects with significant hematologic abnormalities