The primary objective is efficacy on the Alveolar-arterial oxygen difference after 24-weeks treatment. Secondary objectives are tolerance to exercise, effect on Quality of Life, time to Whole Lung Lavage (WLL), effect on pulmonary function, effect on dyspnea and cough, and effect on computed tomography (CT) scoring. Number of reported adverse events (AEs), serious AEs, and adverse drug reactions will be monitored.