Pirfenidone in patients with unclassifiable progressive fibrosing interstitial lung disease: a double-blind, randomised, placebo-controlled, phase 2 trial

At present, no approved pharmacotherapies are available for unclassifiable interstitial lung disease (ILD), which is characterised by progressive fibrosis of the lung. We aimed to assess the efficacy and safety of pirfenidone in patients with progressive fibrosing unclassifiable ILD. We did a multicentre, double-blind, randomised, placebo-controlled phase 2 trial at 70 centres in Australia, Belgium, Canada, Czech Republic, Denmark, Germany, Greece, Ireland, Israel, Italy, Poland, Portugal, Spain, and the UK. Eligible patients (aged ≥18–85 years) had progressive fibrosing unclassifiable ILD, a percent predicted forced vital capacity (FVC) of 45% or higher and percent predicted carbon monoxide diffusing capacity (DLco) of 30% or higher, more than 10% fibrosis on high-resolution CT, and a high-resolution CT from the previous 12 months. Patients were randomly assigned (1:1) to 2403 mg oral pirfenidone daily or placebo using a central validated interactive voice or web-based response system, stratified by concomitant mycophenolate mofetil use and presence or absence of interstitial pneumonia with autoimmune features. Investigators, site personnel, and patients were masked to treatment assignment. The primary endpoint was mean predicted change in FVC from baseline over 24 weeks, measured by daily home spirometry. Secondary endpoints were change in FVC measured by site spirometry, proportion of patients who had a more than 5% or more than 10% absolute or relative decline in percent predicted FVC measured by clinic-based spirometry, change in percent predicted DLco, change in 6-min walk distance (6MWD), change in University of California San Diego-Shortness of Breath Questionnaire (UCSD-SOBQ) score, change in Leicester Cough Questionnaire score, change in cough visual analogue scale, and changes in total and subscores of the St George's Respiratory Questionnaire (SGRQ), all of which were compared with baseline. Additional secondary endpoints included proportion of patients who had non-elective hospitalisation (respiratory and all-cause) and acute exacerbations, and progression-free survival. Efficacy was analysed in the intention-to-treat (ITT) population, which included all randomly assigned patients. Safety was assessed in the safety analysis set, which included all randomly assigned patients who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, NCT03099187, and is no longer recruiting. Between May 15, 2017, and June 5,