A Study Evaluating the Safety and Efficacy of Inhaled AP01 in Participants With Progressive Pulmonary Fibrosis

A randomized, double-blind, placebo-controlled clinical study to evaluate the safety and efficacy of 2 doses of inhaled pirfenidone (AP01) versus placebo on top of standard of care in participants with PPF over 52 weeks.

Inclusion Criteria: * Participant meets criteria for PPF, as follows: * In subjects with interstitial lung disease (ILD) of known or unknown etiology other than idiopathic pulmonary fibrosis (IPF) who have radiological evidence of pulmonary fibrosis, PPF is defined as: Physiological evidence of disease progression with at least 1 of the following criteria despite treatment with approved or unapproved medications commonly used in practice (per Investigator): 1. Relative decline in FVC ≥10% predicted within the previous 24 months based on documented historical spirometry assessments 2. Relative decline in FVC ≥5% to \2.0 x ULN * Renal disease with a creatinine clearance \< 30 mL/min, calculated according to the Chronic Kidney Disease Epidemiology Collaboration formula. Retesting is allowed once. * Diagnosis of idiopathic pulmonary fibrosis (IPF) based on the ATS diagnostic algorithm for IPF. UIP that is not idiopathic, for example related to rheumatoid arthritis (RA), familial interstitial lung disease (ILD), or other is not exclusionary. * Greater extent of emphysema than of fibrotic ILD on HRCT. Note: CT results must be confirmed through the central over read process. * Significant clinical worsening of PPF between Screening * Participants who cannot meet protocol-specified Baseline stability criteria. FVC Baseline stability is defined as the FVC assessments at Visit 3 being within ±12% of the mean of the FVC assessments obtained at the 2 preceding visits. At Visit 3, if the pre-dose FVC is outside of ±12% range, the participant will not be randomized and will be considered a screen failure.