A disease progression model of longitudinal lung function decline in idiopathic pulmonary fibrosis patients.

Pirfenidone and nintedanib are the first two FDA-approved therapies for treatment of idiopathic pulmonary fibrosis (IPF). The clinical programs for pirfenidone and nintedanib included 1132 patients in the placebo arms and 1691 patients in the treatment arms across 6 trials. We developed a disease progression model to characterize the observed variability in lung function decline, measured as percent predicted forced vital capacity (%p-FVC), and its decrease in decline after treatment. The non-linear longitudinal change in %p-FVC was best described by a Weibull function. The median decreased decline in %p-FVC after treatment was estimated to be 1.50% (95% CI [1.12, 1.79]) and 1.96% (95% CI [1.47, 2.36]) at week 26 and week 52, respectively. Smoking status, weight, %p-FVC, %p-DLco and oxygen use at baseline were identified as significant covariates affecting decline in %p-FVC. The decreased decline in %p-FVC were observed among all subgroups of interest, of which the effects were larger at 1 year compared to 6 months. Based on the disease progression model smoking status and oxygen use at baseline may affect the treatment effect size. At week 52, the decreased decline in %p-FVC for current smokers and patients with oxygen use at baseline were 1.56 (90% CI [1.02, 1.99]) and 2.32 (90% CI [1.74, 2.86]), respectively. These prognostic factors may be used to enrich studies with patients who are more likely to respond to treatment, by demonstrating a lesser decline in lung function, and therefore provide the potential to allow for IPF studies with smaller study populations or shorter durations.

Acute Exacerbation and Decline in Forced Vital Capacity Are Associated with Increased Mortality in Idiopathic Pulmonary Fibrosis.

RATIONALE: Exploration of FVC as it relates to mortality in idiopathic pulmonary fibrosis (IPF), a chronic, progressive, and ultimately fatal parenchymal lung disease, is important both clinically and to the current drug development paradigm. We evaluated the association between FVC decline and mortality in what is to our knowledge the largest well-characterized placebo cohort to date. Additionally, we sought to explore the risk of death caused by acute exacerbations and to further validate previously identified baseline predictors of mortality. OBJECTIVES: To validate and further characterize FVC decline, acute exacerbations, and previously identified baseline predictors as they relate to risk of death. METHODS: A total of 1,132 placebo subjects from six studies used for the clinical development of nintedanib and pirfenidone for the treatment of IPF were included in the present analysis. Deaths were captured as all-cause mortality. A stratified Cox proportional hazards model was used to test the association between baseline predictors, decline in FVC % predicted from baseline, acute exacerbations, and death. Decline in FVC % predicted and exacerbations were treated as time-varying covariates. RESULTS: Subjects were followed for a mean of 60 weeks. At baseline, age, smoking status, lower FVC % predicted, and lower diffusing capacity of the lung for carbon monoxide % predicted were associated with an increased risk of death. The risk of death was also increased for subjects having one or more exacerbations with a hazard ratio (HR) of 10.3 (95% confidence interval [CI], 5.7-18.7). Compared with an FVC % predicted absolute decline from baseline at any time during the study of less than 5%, a decline greater than or equal to 10% to less than 15% was associated with an increased risk of death, with an HR of 2.2 (95% CI, 1.1-4.4), as was a decline greater than or equal to 15%, which was estimated with an HR of 6.1 (95% CI, 3.1-11.8). A decline ranging from greater than or equal to 5% to less than 10% was not associated with increased mortality. CONCLUSIONS: Our analyses validate the importance of baseline FVC, diffusing capacity of the lung for carbon monoxide, age, and smoking status as predictors of mortality and strengthen the association between decline in FVC and exacerbations with death, verifying a decline in FVC as an appropriate endpoint in IPF drug development. Clinical trial registered with www.clinicaltrials.gov (NCT00514683, NCT01335464, NCT01335477, NCT00287729, NCT00287716, and NCT01366209).

The lysophosphatidic acid receptor LPA1 links pulmonary fibrosis to lung injury by mediating fibroblast recruitment and vascular leak.

Aberrant wound-healing responses to injury have been implicated in the development of pulmonary fibrosis, but the mediators directing these pathologic responses have yet to be fully identified. We show that lysophosphatidic acid levels increase in bronchoalveolar lavage fluid following lung injury in the bleomycin model of pulmonary fibrosis, and that mice lacking one of its receptors, LPA1, are markedly protected from fibrosis and mortality in this model. The absence of LPA1 led to reduced fibroblast recruitment and vascular leak, two responses that may be excessive when injury leads to fibrosis rather than to repair, whereas leukocyte recruitment was preserved during the first week after injury. In persons with idiopathic pulmonary fibrosis, lysophosphatidic acid levels in bronchoalveolar lavage fluid were also increased, and inhibition of LPA1 markedly reduced fibroblast responses to the chemotactic activity of this fluid. LPA1 therefore represents a new therapeutic target for diseases in which aberrant responses to injury contribute to fibrosis, such as idiopathic pulmonary fibrosis.