Oral Iloprost for the Prevention of Lung Cancer In Former Smokers

PRIMARY OBJECTIVE: I.To determine if oral iloprost, starting at 50 ug twice daily (BID) and increased monthly to a final dose of 150 ug BID as tolerated, compared to placebo for 6 months is effective in reducing endobronchial dysplasia in former smokers who have mild or worse dysplasia on an endobronchial biopsy at baseline bronchoscopy. SECONDARY OBJECTIVES: I. To determine if treatment with oral iloprost compared to placebo results in a change in average dysplasia (over all sites of mild or greater dysplasia). II. To determine safety of treatment with oral iloprost. EXPLORATORY OBJECTIVES: I. To determine if treatment with oral iloprost compared to placebo results in a change in response rate defined as \>= 1 point reduction in maximum dysplasia. II. To determine if the in vitro differentiation response of bronchial epithelial cell progenitors cultured at the air liquid interface is predictive of the in vivo response of dysplasia improvement (to be done only in participants recruited in Colorado). III. To determine if treatment with oral iloprost compared to placebo results in a decrease in the volume of pure ground glass opacities (GGOs) on chest computed tomography (CT). IV. To determine if treatment with oral iloprost compared to placebo increases peripheral lung epithelial progenitor counts, measured by organoid formation in a three dimensional culture system seeded from distal airway brushings (to be done only in participants recruited in Colorado). V. To determine if oral iloprost reduces the incidence of lung cancer compared to placebo. VI. To evaluate the ability of 3-dimensional morphologic analysis of expectorated sputum by LuCED compared to standard sputum cytopathology to predict endobronchial dysplasia and measure response to iloprost. VII. To evaluate histologic response by alternative criteria. OUTLINE: Patients are randomized in 1 of 2 arms. ARM I: Patients receive iloprost orally (PO) BID for a 180 days in the absence of unacceptable toxicity. Patients undergo bronchoscopy with biopsies and brushings at day 180. ARM II: Patients receive iloprost placebo PO BID for a 180 days in the absence of unacceptable toxicity. Patients undergo bronchoscopy with biopsies and brushings at day 180. After completion of study treatment, patients are followed up for 30 days.