After week 72, patients who meet the Progression of Disease (POD) definition, which is a ≥ 10% absolute decrease in percent predicted FVC or a ≥ 15% absolute decrease in percent predicted carbon monoxide diffusing capacity (DLco), will be eligible to receive permitted IPF therapies in addition to their blinded study drug. Permitted IPF therapies include corticosteroids, azathioprine, cyclophosphamide and N-acetyl-cysteine (with restrictions).