Addition of antifibrotic therapy to immunosuppression in hypersensitivity pneumonitis: A case series

Hypersensitivity pneumonitis has historically been treated with immunosuppression, but recently nintedanib was approved for the treatment of progressive fibrotic HP. One limitation of INBUILD is that the only immunosuppression (IS) permitted at the time of enrollment was glucocorticoids at a dose of less than 20mg per day, so the additive effect of antifibrotic (AF) therapy to IS in HP remains unclear. We present 5 cases of patients with HP for whom AF therapy was added to IS. Trends observed in the cohort include reduced decline in FVC, oxygen requirement, and symptoms in the year after adding AF to IS in 4 of the 5 patients. All 5 patients (100%) in our series demonstrated progression in the year prior to initiation of antifibrotic based on criteria outlined in the INBUILD trial, but only 1 of 5 (20%) progressed in the year after AF. There was a significant decrease in the rate of relative decline in % predicted FVC in the 12 months after initiation of antifibrotic compared to the 12 months prior to antifibrotic (0.4% ±7.6 vs −17.5% ±7.6, p = 0.0495). Compared to the 12 months prior to antifibrotic therapy, fewer patients met criteria for progression in the 12 months after initiating antifibrotic therapy (p = 0.048). Similarly, fewer patients met criteria for progression in the 6 months after initiating antifibrotic therapy compared to the 6 months prior (p = 0.048). A larger study with control groups on IS alone and AF alone is needed to confirm the role of AF therapy in combination with IS in patients with HP.