Multicenter randomized phase 2 trial of pirfenidone for grade 2-3 radiation-induced lung injury

Radiation-induced lung injury is a major dose-limiting toxicity in thoracic radiotherapy. Pirfenidone is an oral antifibrotic drug that is often used to treat idiopathic pulmonary fibrosis. A phase 2 trial at ten medical centers in China evaluated efficacy and safety of pirfenidone in patients with grade 2 or grade 3 radiation-induced lung injury. Patients were randomized to receive pirfenidone plus glucocorticoids (n=67) or glucocorticoids alone (n=67). The primary endpoint was the change in percentage of carbon monoxide diffusing capacity (DLCO%) from baseline to week 24. The median follow-up was 9.2 months. At week 24, the pirfenidone group showed an 8.0% improvement from baseline in DLCO%, whereas the control group showed a 2.4% reduction (p=0.0010). Serious adverse events occurred in 18% of patients in the pirfenidone group and 16% of patients in the control group. There were no treatment-related deaths. The authors conclude that pirfenidone in combination with glucocorticoids provides a potential therapeutic strategy for grade 2 or grade 3 radiation-induced lung injury.