GKT137831 in IPF Patients with Idiopathic Pulmonary Fibrosis

Inclusion Criteria:

1. Age between 40-85 years old.

2. A diagnosis of IPF that fulfills current American Thoracic Society (ATS) ConsensusCriteria.

3. IPF duration <5 years, based on the date of definitive diagnosis.

4. Ability and willingness to give informed consent and adhere to study requirements.

5. Ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) >70% of predicted values

Exclusion Criteria:

1. Diagnosis of major comorbidities expected to interfere with study participation

2. History of malignancy, excluding basal or squamous cell skin cancer and low-riskprostate cancer, the latter defined as stage T1 or T2a, with prostate specificantigen <10 ng/dl. NOX inhibition is not known to promote cancer, and these criteriaare within current guidelines.

3. The occurrence of any acute infection requiring systemic antibiotic therapy within 2weeks prior to Screening (Visit 1).

4. Treatment for >14 days within the preceding month with >20 mg. prednisone (orequivalent) or any treatment during the last month with a cellular immunosuppressant (e.g., cyclophosphamide, methotrexate, calcineurin inhibitors, etc.), givenincreased risks of opportunistic infections.

5. Treatment with any investigational agent within 4 weeks of Screening (Visit 1) or 5half-lives of the investigational medicinal product (whichever is longer).

6. Fertile women who do not agree to contraception or abstinence, or who are breastfeeding. IPF is a disease of older adults, and male predominant, so this will not bea frequent consideration.

7. Subjects with known hypersensitivity to GKT137831 or its excipients (e.g. capsule "bulking" agents).

8. A history of bone marrow disorder including aplastic anemia, or marked anemiadefined as hemoglobin < 10.0 g/dL (or 6.2 mmol/L).

9. Severe cardiovascular disease, defined as any of the following within the preceding 12 weeks: acute myocardial infarction or unstable angina, a coronaryrevascularization procedure, congestive heart failure (NYHA Class III or IV), orstroke, including a transient ischemic attack.

10. Evidence of cardiac conducting abnormalities, defined as second or third degreeatrial-ventricular (AV) block not successfully treated with a pacemaker, or apersonal or family history of long QT syndrome (QTc interval >450 msec for males or 470 msec for females).

11. End-stage renal disease requiring dialysis.

12. Undergoing transplantation evaluation, or listed with the United Network for OrganSharing (UNOS) as a lung transplantation candidate at the time of enrollment in thistrial.

13. Liver function tests (transaminases, alkaline phosphatase, direct and totalbilirubin) >3x upper limit of normal values