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

Inclusion criteria: * Adult (aged \>18 years) male or female patients, * Documented diagnosis of IPF according to the current American Thoracic Society/European Respiratory Society/Japanese Respiratory Society/American Latin Thoracic Association (ATS/ERS/JRS/ALTA) guidelines Exclusion criteria: * Forced vital capacity (FVC) \<50% of predicted value Carbon monoxide diffusing lung capacity (DLCO) (corrected for hemoglobin) \<35% predicted value * Oxygen saturation \<90% by pulse oximetry while breathing ambient air at rest (sitting position for 10 min) * Known diagnosis of significant respiratory disorders other than IPF * Active vasculopathy or use of vasoactive drugs * Known HIV or chronic viral hepatitis * Patients with active tuberculosis or latent tuberculosis infection * Evidence of any clinically significant, severe or unstable, acute or chronically progressive medical (other than IPF) or surgical disorder, or any condition that may affect patient safety in the judgment of the investigator * Clinically significant abnormal ECG at screening * Clinically significant laboratory tests at screening * Current history of substance and/or alcohol abuse * Females who are lactating or who are pregnant. * Use of any registered therapy targeted to treat IPF within 4 weeks prior to screening * Use of any cytotoxic/immunosuppressive agent including but not limited to azathioprine, cyclophosphamide, methotrexate and cyclosporine within 4 weeks prior to screening The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.