The purpose of the study is to evaluate the safety and tolerability of multiple-doses of tralokinumab in Japanese patients with Idiopathic Pulmonary Fibrosis.

This is a phase II, multicenter, blinded within cohort, dose-escalation study to evaluate the safety and tolerability of two ascending doses of tralokinumab in Japanese patients aged ≥ 50 years with mild to moderate Idiopathic Pulmonary Fibrosis.

Inclusion Criteria:

• Provision of informed consent prior to any study specific procedures

• Confirmed IPF diagnosis for ≤ 5 years prior to Visit 1 (screening). Confirmation of diagnosis of IPF

• Mild to moderate IPF to include all of the following at Visit 1

  1. FVC ≥ 50% and ≤ 90% predicted normal
  2. Partial pressure of oxygen in arterial blood (PaO2) of ≥ 55 mmHg on room air, or oxygen saturation by pulse oximetry (SpO2) of ≥ 90% on room air at rest
  3. Hemoglobin-corrected diffusion capacity for carbon monoxide (DLCO) ≥ 30% and ≤ 90% predicted normal

Exclusion Criteria:

• History of clinically significant environmental exposure (eg, domestic and occupational) to a known cause of pulmonary fibrosis
• Diagnosis of connective tissue disease or drug toxicity as the likely cause of the interstitial disease
• A suspected IPF exacerbation not fully resolved and treatment completed ≤ 14 days prior to Visit 1
• A suspected IPF exacerbation during the screening period
• A FEV1/FVC ratio < 0.70 at the time of Visit 1 (postbronchodilator)
• The extent of emphysema on the HRCT is greater than the extent of fibrosis

Safety population

From baseline to Week 48 (treatment-emergent only)