Pirfenidone in patients with idiopathic pulmonary fibrosis and more advanced lung function impairment

Background: Patients with idiopathic pulmonary fibrosis (IPF) demonstrate a range of lung function impairment. However, the efficacy of antifibrotics compared with placebo has not been assessed in patients with more advanced disease. This post-hoc analysis investigated the efficacy and safety of pirfenidone versus placebo in patients with IPF and more advanced lung function impairment, defined as percent predicted forced vital capacity (% FVC) < 50% and/or percent predicted carbon monoxide diffusing capacity<35%. Methods: Patients randomised to pirfenidone 2,403 mg/day or placebo in the ASCEND (NCT01366209) and CAPACITY (NCT00287716; NCT00287729) trials with more advanced baseline lung function impairment (pirfenidone, n= 90; placebo, n= 80) were included. Mortality, lung function, hospitalisation, exercise capacity and dyspnoea were investigated over 52 weeks. Results: At Week 52 versus placebo, pirfenidone was associated with significantly lower risks of all-cause mortality (hazard ratio [HR] 0.28; 95% confidence interval [CI] 0.09-0.86; p= 0.0180), >= 10% absolute % FVC decline or all-cause mortality (HR 0.40; 95% CI 0.23-0.69; p= 0.0006) and >= 10% absolute % FVC decline or respiratory-related hospitalisation or all-cause mortality (HR 0.46; 95% CI 0.28-0.76; p= 0.0018). At Week 52, median treatment differences favouring pirfenidone were 36.7m for 6-min walk distance and -8.0 points for the University of California-San Diego Shortness of Breath Questionnaire total score. Treatment-emergent adverse events (TEAEs) led to discontinuation in 14.4% and 21.3% of patients with pirfenidone and placebo, respectively. Conclusion: Pirfenidone demonstrated clinically relevant benefits across multiple domains in patients with IPF and more advanced disease without an increased risk of discontinuation due to TEAEs.