The Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to pirfenidone (Esbriet®; Genentech) for adults with fibrosing interstitial lung disease (ILD) who cannot be classified with moderate or high confidence into any other category of fibrosing ILD (“unclassifiable” interstitial lung disease [uILD]).

The designation was based on data from a multicenter, double-blind, placebo-controlled phase 2 trial that evaluated the efficacy and safety of pirfenidone in patients with uILD (N=253). Patients were randomized 1:1 to receive either pirfenidone 801mg (n=127) or placebo (n=126) three times daily for 24 weeks. 

The primary efficacy end point was the mean predicted change in forced vital capacity (FVC) from baseline over 24 weeks, measured by daily home spirometry. Key secondary end points included change in FVC measured by site spirometry, change in percent predicted carbon monoxide diffusing capacity (DLco), and change in 6-minute walk distance (6MWD).

Findings from the trial showed the predicted median change in FVC measured by home spirometry was -87.7mL (Q1-Q3 -338.1 to 148.6) in the pirfenidone group vs -157.1mL (–370.9 to 70.1) in the placebo group over 24 weeks. Additionally, pirfenidone-treated patients had a lower predicted mean change in FVC measured by site spirometry vs placebo (treatment difference 95.3mL; P=.002). Mean change in DLco and 6MWD from baseline was −0.7% and −2.0m for the pirfenidone group compared with and −2.5% and -26.7m for the placebo group.

The safety profile of pirfenidone was comparable with that observed in previous trials. The most common treatment-emergent adverse events were gastrointestinal disorders, fatigue, and rash.

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Pirfenidone is currently marketed under the brand name Esbriet for the treatment of idiopathic pulmonary fibrosis in adults. The product is supplied as 267mg tablets or capsules and 801mg tablets.

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