Pilot Study of Pirfenidone in Pulmonary Fibrosis With Anti-myeloperoxydase Antibodies

Inclusion Criteria: * Age \> 18 years * Presence of anti-MPO antibody (ELISA) at inclusion or during pulmonary fibrosis follow-up and/or diagnosis of anti-MPO associated vasculitis according to the 2012 Revised International Chapel Hill Consensus Conference definitions * Definite or possible Usual Interstitial Pneumonia or Non Specific Interstitial Pneumonia based on high-resolution computed tomography * Presence of pulmonary fibrosis, defined as a range of 50 to 90% of the %FVC and a range of 30 to 90% of the %DLCO * Pulmonary fibrosis refractory (according to the investigator's judgment) to a conventional regimen used for anti-MPO associated vasculitis when a treatment against vasculitis has been used * Have the ability to understand the requirements of the study, provide written informed consent (including consent for the use and disclosure of research-related health information) and comply with the study protocol procedures (including required study visits) * Have affiliation with a mode of social security (profit our being entitled). Exclusion Criteria: * Other type of systemic vasculitis; * Active vasculitis defined by Birmingham Vasculitis Activity Score \>3 (BVAS) ; * Contraindication to Pirfenidone; * Unable to perform pulmonary function test (PFT); * Pregnancy or lactation. Women of childbearing capacity are required to have a negative serum pregnancy test before treatment and must agree to maintain highly effective contraception by practicing abstinence or by us…