Modification of the course of disease progression in idiopathic pulmonary fibrosis by pirfenidone: evidence of the potential for disease reversal

Idiopathic pulmonary fibrosis (IPF) is a fibrosing pneumonia of unknown causation with a chronic, progressive course that may be modified by treatment with the antifibrotic agents, pirfenidone and nintedanib. Both drugs have been shown to slow disease progression, but, in rare cases, pirfenidone has been shown to stabilise and even improve lung function. We present a case of a patient whose lung function and pathognomonic features on CT imaging improved significantly on commencement of treatment with pirfenidone. Withholding pirfenidone was associated with a functional and morphological deterioration on imaging that subsequently reversed and stabilised following recommencement of this treatment. We discuss potential mechanisms that might explain this treatment response, compare our case to others described previously and the potential consequences that restricted prescribing within a specified range of vital capacity may have on the opportunity to influence the natural history of IPF early before irreversible fibrosis develops.