A Randomized, Double-Blinded, Placebo-Controlled, Phase 2 Study of Safety, Tolerability and Efficacy of Pirfenidone in Patients with Rheumatoid Arthritis Interstitial Lung Disease

BackgroundInterstitial lung disease (ILD) is a known complication of rheumatoid arthritis (RA) with a lifetime risk in any individual of 7.7%. The TRAIL1 trial was a randomized, double-blinded, placebo-controlled, phase 2 study of safety, tolerability, and efficacy of pirfenidone for the treatment of patients with RA-ILD. MethodsThe TRAIL1 was a phase 2 trial intended to enroll 270 adult patients (18 to 85 years) with established RA-ILD at 33 sites in 4 countries. Patients were randomly assigned (1:1) to 2,403 mg oral pirfenidone or placebo daily. The primary endpoint was the incidence of the composite endpoint of decline from baseline in percent predicted forced vital capacity (FVC%) of 10% or greater or death during the 52-week treatment period. Key secondary endpoints included change in absolute and FVC% over 52 weeks. FindingsThe trial was stopped early due to slow recruitment and soon after the shutdown of clinical trials as a consequence of the coronavirus disease 2019 (COVID-19) pandemic. Data from 123 patients enrolled were analyzed. The primary endpoint was met by 11.1% on pirfenidone vs. 15% on placebo [OR=0.67 (0.22, 2.03), p=0.48]. Subjects receiving pirfenidone had a slower rate of decline in lung function as measured by estimated annual change in FVC(ml) (-66 vs. -146, p=0.0082) and FVC(%) (-1.02 vs. -3.21, p=0.0028). This effect on decline was also seen when analyzed within participants with baseline usual interstitial pneumonia (UIP) pattern on HRCT (FVC(ml) (-43 vs. -169, p=0.0014) and FVC% (-0.2 vs. -3.81, p=0.0002)). There was no significant difference in the rate of treatment-emergent serious adverse events. InterpretationDue to early termination of the study, results should be interpreted with caution. Despite being underpowered to evaluate the primary endpoint, pirfenidone slowed the rate of decline of FVC over time in subjects with RA-ILD. Safety in patients with RA-ILD was similar to that seen in other pirfenidone trials. FundingFunding for this investigator initiated trial was provided by Genentech, Inc. to Ivan O. Rosas, MD, on behalf of the TRAIL1 Investigators.