Azathioprine and Prednisone in the Treatment of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a diffuse lung disease, associated with the histological appearance of usual interstitial pneumonia (UIP), with an inexorably deteriorating clinical course. Prognosis is poor, reported median survival is less than 3 years. The prevalence is estimated as being 3 to 10 per 100.000 in different Western populations. To date, no pharmacological therapy has been proven to alter or reverse the pathogenic process of IPF. Most treatments trials have been observational case series of small patient populations and very few have been randomized, prospective and placebo-controlled. Two recent Cochrane reviews investigated the role of corticosteroids and other immunomodulatory agents and concluded that there is no evidence for their use in IPF. Most current therapies are targeted to suppress the inflammatory component of the disease, based on the theory that it would be chronic alveolar inflammation which leads to parenchymal remodeling and fibrosis. Recently, a hypothesis that has gained acceptance suggests that fibrosis may result directly from alveolar injury, promoting an abnormal fibrogenic repair mediated by fibroblasts and myofibroblasts. One of the cytotoxic agents most widely used and better tolerated in the management of IPF is azathioprine. Based upon limited data available and from a single small high quality randomized controlled trial (RCT), this drug appears to confer, given in conjunction with prednisone, a marginal long term survival advantage. Since this combination therapy is associated serious adverse effect, we planned to design a trial of low dose corticosteroid and azathioprine versus placebo in management of IPF, evaluating progression-free survival. Our study hypothesis is: Combined therapy with azathioprine and corticosteroids improves progression-free survival in patients with the diagnosis of IPF.