An Open-label Study With Pirfenidone on Chronic Hypersensitivity Pneumonitis

Chronic hypersensitivity pneumonitis (cHP) represents a severe lung disease often evolving to fibrosis with the subsequent destruction of the lung parenchyma. There are no approved therapies with confirmed efficacy to deal with this disease.

We performed an open-label, proof of concept study, to evaluate the efficacy and safety of pirfenidone added to immunosuppressive drugs on the treatment of cHP. We included 22 patients assigned to two groups: Group 1, nine patients that received prednisone plus azathioprine and Group 2, thirteen patients, received prednisone plus azathioprine and pirfenidone (ClinicalTrials.gov identifier NCT02496182). There were no significant imbalances in clinically relevant baseline characteristics between two study groups.

After 1 year of treatment, inclusion of pirfenidone was not associated with improved forced vital capacity (primary end-point). A not significant tendency to show higher improvement of diffusion capacity of the lung for carbon monoxide (D_LCO) was observed in the group receiving pirfenidone (p=0.06). Likewise, a significant improvement in the total score on the SGRQ was found in the group 2 (p=0.02) without differences in other two questionnaires related to quality of life (ATAQ-IPF and EQ-5D-3L). HRCT showed a decrease of the ground glass attenuation without changes in the fibrotic lesions and without differences between both groups.

These findings suggest that the addition of pirfenidone to the anti-inflammatory treatment in patients with chronic HP may improve the outcome with acceptable safety profile. However, prospective randomized double-blind, placebo-controlled trials in largest cohorts are needed to validate its efficacy.