Exclusion Criteria: 1. Female subjects who are pregnant or nursing.
2. Infiltrative lung disease other than IPF, including any of the other types of idiopathic interstitial pneumonias (American Thoracic Society, 2002); lung diseases related to exposure to fibrogenic agents or other environmental toxins or drugs; other types of occupational lung diseases; granulomatous lung diseases; pulmonary vascular diseases; systemic diseases, including vasculitis and connective tissue diseases.
3. HRCT scan findings at Screening Visit 2 Inconsistent with UIP Pattern.
4. Pathology diagnosis on surgical lung biopsy is anything other than UIP Pattern.
5. History of other types of respiratory diseases including diseases or disorders of the airways, lung parenchyma, pleural space, mediastinum, diaphragm, or chest wall that, in the opinion of the investigator, would impact the endpoints in the protocol or otherwise preclude the subject’s participation in the study.
6. History of any other respiratory, cardiovascular, renal, hepatic, metabolic, neurologic, hematologic, or other medical conditions that, in the opinion of the investigator, would preclude the subject’s participation in the study.
7. Clinically important abnormal laboratory tests (including serum creatinine ≥1.5 x upper limit of normal [ULN], hemoglobin <8 g/dL, white blood cells <3,000/mm3, platelets less than 100,000/mm3, international normalized ratio (INR) >1.5, serum albumin <3.0 g/dL, serum total bilirubin >ULN, serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≥2 x ULN, or serum alkaline phosphatase ≥2 x ULN.
8. Upper or lower respiratory tract infection of any type within 4 weeks of Screening Visit 1.
9. Acute exacerbation of IPF within 3 months of Screening Visit 1.
10. Evidence of obstructive lung disease by any of the following criteria: Forced Expiratory Volume in One Second/Forced Vital Capacity (FEV1/FVC) ratio <0.65, or residual volume >120 percent of predicted value, or extent of emphysema on HRCT greater than the extent of fibrosis on HRCT.
11. DLCO <30% of the predicted value, corrected for hemoglobin but not for alveolar volume.
12. High likelihood of lung transplantation (in the opinion of the investigator) within 6 months after Day 1.
13. Chronic heart failure categorized as New York Heart Association Class III or IV (this applies to symptoms of chronic heart failure, not IPF); clinical diagnosis of cor pulmonale requiring specific treatment; or severe pulmonary hypertension requiring specific treatment that, in the opinion of the investigator, would preclude the subject’s participation in the study.
14. Use of any of the following medications within 4 weeks preceding Screening Visit 1: warfarin, sildenafil, pirfenidone, azathioprine, cyclophosphamide, interferon gamma-1b, D-penicillamine, methotrexate, cyclosporine, leflunomide, colchicine, bosentan, ambrisentan, aminobenzoate, mycophenolate mofetil, imatinib, relaxin, etanercept, adalimumab, infliximab, anakinra, abatacept, and rituximab.
Note: Treatment of IPF with oral prednisone (or equivalent oral corticosteroid) or N-acetylcysteine (NAC) or both during the Treatment Period is acceptable provided that (1) daily treatment with either or both of these medications has been continuous for at least 4 weeks prior to Screening Visit 1, and (2) daily treatment with either or both of these medications will be continued throughout the Treatment Period at stable doses not to exceed the following: prednisone (or equivalent oral corticosteroid) 10 mg daily, NAC 1800 mg daily.
15. Receipt of any investigational drug within 6 weeks prior to Screening Visit 1.
16. History of cancer of any type in the 5 years preceding Screening Visit 1, excluding non-melanomatous skin cancer, localized bladder cancer, or in situ cervical cancer. Enrollment of subjects with any history of cancer must be pre-approved by the FibroGen medical monitor.
17. Trauma or surgical procedures requiring hospitalization within 4 weeks prior to Screening Visit 1.
18. Planned elective surgery during the study including 4 weeks following the final dose of study drug.
19. History of allergic or anaphylactic reaction to human, humanized, chimeric or murine monoclonal antibodies.
20. The principal investigator judges that the subject will be unable to fully participate in the study and complete it for any reason, including inability to cooperate with study personnel or a history of noncompliance to the medical regimen (i.e., subjects who would be expected to comply poorly with study procedures and treatment), addiction, or any clinically significant medical or psychiatric condition considered a high risk for not successfully completing participation in an investigational study.
21. Body Mass Index (BMI) >35 (Cohort 1); weight >130 kg (Cohort 2).
22. Previous treatment with FG-3019. 23. History of inadequate IV access.