A Study of Lebrikizumab in Participants With Idiopathic Pulmonary Fibrosis (IPF)

Inclusion Criteria

• Have a diagnosis of IPF within the previous 5 years from time of screening and confirmed at baseline
• FVC >/=40 percent (%) and /=25% and /=100 meters unassisted in 6 minutes
• Cohort A: No background IPF therapy for >/=4 weeks allowed prior to randomization and throughout the placebo-controlled study period
• Cohort B: Tolerated dose of pirfenidone /=4 weeks required prior to randomization and throughout the placebo-controlled study period

Exclusion Criteria

• History of severe allergic reaction or anaphylactic reaction to a biologic agent or known hypersensitivity to any component of the lebrikizumab injection
• Evidence of other known causes of interstitial lung disease
• Lung transplant expected within 12 months of screening
• Evidence of clinically significant lung disease other than IPF
• Post-bronchodilator forced expiratory volume in 1 second (FEV1)/FVC ratio /=12% predicted and 200 milliliters increase in FEV1 or FVC
• Class IV New York Heart Association chronic heart failure or historical evidence of left ventricular ejection fraction <35%
• Hospitalization due to an exacerbation of IPF within 4 weeks prior to or during screening
• Known current malignancy or current evaluation for potential malignancy
• Listeria monocytogenes infection or active parasitic infection within 6 months prior to Day 1, Visit 2
• Active tuberculosis requiring treatment within 12 months of screening
• Known immunodeficiency, including but not limited to human immunodeficiency virus infection
• Past use of any anti-interleukin (IL)-13 or anti-IL-4/IL-13 therapy, including lebrikizumab
• Evidence of acute or chronic hepatitis or known liver cirrhosis

Exclusions Criteria Limited to Cohort B:

• Known achalasia, esophageal stricture, or esophageal dysfunction sufficient to limit the ability to swallow oral medication
• Tobacco smoking or use of tobacco-related products within 3 months of screening or unwillingness to avoid smoking throughout the study period
• Known or suspected peptic ulcer
• Any condition that, as assessed by the investigator, might be significantly exacerbated by the known side effects associated with pirfenidone
• Creatinine clearance <40 milliliters/minute, calculated using the Cockcroft-Gault formula
• Use of following therapies within 4 weeks of randomization (Day 1, Visit 2) or during the study: Strong inhibitors of CYP1A2 (Cytochrome P450 Family 1 Subfamily A Member 2) (example: fluvoxamine or enoxacin); Moderate inducers of CYP1A2 (limited to tobacco smoking and tobacco-related products)