To Evaluate the Effect of Different Doses of SAR156597 Given to Patients With Idiopathic Pulmonary Fibrosis (IPF)

Primary Objective: To assess in adult patients with Idiopathic Pulmonary Fibrosis (IPF) the safety and tolerability of ascending doses of SAR156597 administered subcutaneously (SC) once weekly over a 6-week period. Secondary Objectives: To assess in adult patients with IPF: * The pharmacodynamic effects of SAR156597, as measured on pulmonary function tests (PFTs), pulse oximetry and patient reported outcome and peripheral blood biomarkers. * The trough plasma concentrations of SAR156597 * The potential immunogenicity of SAR156597.