This is a Phase 2, open-label, single-arm study of the safety and tolerability of PBI-4050 800 mg daily oral administration in 40 adult patients with IPF.

This Phase 2 multi-centre study will be performed by 6 Canadian sites. It is an open-label, single-arm study in patients with Idiopathic Pulmonary Fibrosis (IPF) aged 40 years and older.

The duration of study participation is approximately 20 weeks for each patient and comprises 6 study visits.

Inclusion Criteria:

1. Patient is an adult aged 40 years or older
2. Patient has signed written informed consent.
3. Patient has been diagnosed of IPF according to the most recent guideline on IPF diagnosis and management released by American Thoracic Society (ATS), European Respiratory Society (ERS), Japanese Respiratory Society (JRS), and Latin American Thoracic Association (ALAT).
4. Female patients of childbearing potential must have a negative urine pregnancy test and agree to use adequate birth control from screening throughout the study and for 30 days after the last study drug administration.
5. If a male patient has not been vasectomized at least 6 months before screening and partners with a woman of childbearing potential, he must be willing to use an acceptable contraceptive method throughout the study and for 30 days after the last study drug administration.

Exclusion Criteria:

1. Patient has a known diagnosis of a respiratory disorder other than IPF.
2. Substantial emphysema on high resolution computer tomography (HRCT) with degree of emphysema greater than fibrosis.
3. Patient is an active smoker.
4. Patient has evidence of active infection.
5. Patients currently has or has a history of cancer, except basal cell carcinoma or squamous cell carcinoma of the skin.
6. Patient has a concurrent medical or psychological condition that, in the investigator's opinion, may compromise the patient's ability to participate in the study or give informed consent, or may complicate the evaluations of the study drug.
7. Patient is receiving another investigational treatment for IPF at screening and/or plans to receive an investigational treatment for IPF during the current study.
8. Patient has chronic hepatitis or significantly elevated liver enzyme levels, defined as alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≥ 2.5 × upper limit of normal (ULN) or total bilirubin above ULN.
9. Female patient who is pregnant, breast-feeding, or planning a pregnancy during the course of the study.
10. Woman of childbearing potential who is unwilling to use adequate birth control throughout the duration of the study.
11. Patient has participated in an investigational clinical trial during the last 4 weeks.