Inclusion Criteria:

• Age 40 to 85 years, inclusive, at screening initiation. 
• Diagnosis of IPF as defined by ATS/ERS/JRS/ALAT guidelines (Raghu 2018).
• History of IPF diagnosis within the past 5 years with onset defined as the date of the first recorded diagnosis of IPF by HRCT and/or SLB in the medical history. 
• Interstitial pulmonary fibrosis defined by HRCT scan at Screening, with evidence of ≥ 10% to < 50% parenchymal fibrosis (reticulation) and < 25% honeycombing, within the whole lung, as determined by the HRCT central reader. 
• FVCpp value > 45% and < 95% at screening and Day 1(prior to randomization)
• Diffusing capacity of the lungs for carbon monoxide (DLCO) percent of predicted and corrected by Hb value ≥ 25% and ≤ 90% done within 3 months prior to screening may be utilized for screening/ eligibility purposes.
• Both FVC and DLCO testing must be representative of the IPF underlying disease. 
• Not currently receiving treatment for IPF with approved or unapproved therapy. 
• Male subjects with partners of childbearing potential and female subjects of childbearing potential (including those < 1 year postmenopausal) must use a highly effective method of contraception per Clinical Trial Facilitation Group (CTFG) recommendation during the conduct of the study, and for 3 months after the last dose of study drug. Women not of childbearing potential are defined as:
  • Post-menopausal women (defined as at least 12 months with no menses without an alternative medical cause); in women < 45 years of age, a high follicle stimulating hormone (FSH) level in the post-menopausal range may be used to confirm a postmenopausal state in women not using hormonal contraception or hormonal replacement therapy; OR
  • Have had a hysterectomy and/or bilateral oophorectomy, bilateral salpingectomy or bilateral tubal ligation/occlusion, at least 6 weeks prior to screening; OR
  • Have a congenital or acquired condition that prevents childbearing.
• Able to understand and sign a written informed consent form.

Exclusion Criteria:

• Previous exposure to pamrevlumab. 
• Evidence of significant obstructive lung disease by any of the following criteria: (1) forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) ratio < 0.70, or (2) extent of emphysema greater than the extent of fibrosis on HRCT. 
• Female subjects who are pregnant or nursing. 
• Smoking within 3 months of Screening and/or unwilling to avoid smoking throughout the study. 
• Interstitial lung disease other than IPF. 
• The Investigator judges that there has been sustained improvement in the severity of IPF during the 12 months prior to Screening, based on changes in FVC, DLCO, and/or HRCT scans of the chest. 
• 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 primary protocol endpoint or otherwise preclude the subject's participation in the study. 
• Medical conditions (e.g., MI/stroke within the past 3-6 month) or logistical challenges that in the opinion of the Investigator preclude the subject's adequate participation in the study. 
• Poorly controlled chronic heart failure (NYHA Class 3 or above); clinical diagnosis of cor pulmonale requiring specific treatment; or severe pulmonary arterial hypertension requiring specific treatment that, in the opinion of the Investigator, would preclude the subject's participation in the study. 
• Clinically important abnormal laboratory tests (including serum creatinine ≥ 1.5 x upper limit of normal [ULN], hemoglobin (Hb) < 10 g/dL, white blood cells < 3,000/mm^3, platelets less than 100,000/mm^3, serum total bilirubin > 1.5 x ULN, serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≥ 2 x ULN, or serum alkaline phosphatase ≥ 2 x ULN. 
• Ongoing acute IPF exacerbation, or suspicion of such process during screening or randomization, including hospitalization due to acute IPF exacerbation within 4 weeks prior to or during screening.
• High likelihood of lung transplantation (in the opinion of the Investigator) within 6 months after Day 1. 
• Use of any investigational drugs or unapproved therapies, for IPF or not, in the 30 days prior to screening initiation. Or use of approved IPF therapies within 5 half-lives of screening.
• Daily use of PDE-5 inhibitor drugs [e.g., sildenafil, tadalafil, other]. (Note: Intermittent use of one type for erectile dysfunction or severe pulmonary hypertension is allowed). 
• Any history of malignancy likely to result in significant disability or mortality likely to require significant medical or surgical intervention within the next 2 years. This does not include minor surgical procedures for localized cancer; (e.g., basal or squamous cell carcinoma of skin).
• History of allergic or anaphylactic reaction to human, humanized, chimeric or murine monoclonal antibodies, or to any component of the excipient.
• Any condition (other than IPF) that is likely to result in the death of the patient within the next year. 
• The Investigator judges that the subject will be unable to fully participate in the study and complete it for any reason, including inability to comply with study procedures and treatment, addiction, or any other relevant medical or psychiatric conditions.