Late Breaking Abstract - Phase II trial of pirfenidone in patients with progressive fibrosing unclassifiable ILD (uILD)

Introduction: There are no approved therapies for patients with uILD, who may have irreversible ILD. We evaluated efficacy and safety of pirfenidone in patients with progressive fibrosing uILD. Methods: This was a double-blind, randomised, placebo-controlled Phase II trial (NCT03099187). The primary endpoint was predicted FVC change over 24 weeks measured by daily home spirometry; secondary endpoints included changes in FVC (measured at site visits), DLco and 6MWD. Safety was also assessed. Results: 253 patients were randomised and 251 were treated (n=127 pirfenidone; n=124 placebo). Analysis of the primary endpoint was impacted by high intra-individual variability in home spirometry values in both treatment groups, amplified in patients with short observation periods, which prevented application of the planned statistical model. Median (Q1, Q3) FVC change (home spirometry) over 24 weeks was –87.7 mL (–338.1, 148.6) and –157.1 mL (–370.9, 70.1) in pirfenidone and placebo groups, respectively (Table). FVC change measured at site visits considerably favoured pirfenidone over placebo; results for DLco and 6MWD generally trended towards pirfenidone (Table). AE reporting reflected the known safety profile of pirfenidone. Conclusions: The planned statistical model could not be applied to the primary endpoint data. Results of key secondary endpoints suggest patients with progressive fibrosing uILD benefit from pirfenidone.