Maher TM, Corte TJ, Fischer A, et al. - To test pirfenidone for its efficacy and safety in treating patients with progressive fibrosing unclassifiable interstitial lung disease (ILD), researchers undertook this multicentre, double-blind, randomised, placebo-controlled phase 2 trial involving 70 centres in Australia, Belgium, Canada, Czech Republic, Denmark, Germany, Greece, Ireland, Israel, Italy, Poland, Portugal, Spain, and the UK. The eligible patients were randomly allocated (1:1) to 2403 mg oral pirfenidone daily or placebo. Mean predicted alteration in forced vital capacity (FVC) from baseline over 24 weeks, evaluated by daily home spirometry, was the primary endpoint. In the pirfenidone group vs in the placebo group, the predicted median change in FVC over 24 weeks, measured by home spirometry, was −87·7 mL vs −157·1 mL, respectively. Patients treated with pirfenidone vs placebo had lower predicted mean change in FVC, measured by site spirometry, over 24 weeks. Although the application of the planned statistical model to the primary endpoint data was not possible, analysis of key secondary endpoints indicates that pirfenidone as a treatment option could afford benefit to patients with progressive fibrosing unclassifiable ILD. Findings revealed an acceptable safety and tolerability profile of pirfenidone in these patients. Further testing of pirfenidone as an effective treatment for patients with progressive fibrotic unclassifiable ILD was thus supported.