Results from pre-clinical studies with inhaled molgramostim nebuliser solution showed the expected pharmacological effects on white blood cell (WBC) populations locally and systemically in line with observed effects after IV administration of molgramostim. No severe, serious or dose-limiting AEs were observed in the first clinical study in humans (MOL-001). The most common AE was cough, which was reported at a similar incidence for the molgramostim nebuliser solution and placebo. Increases of WBC populations in the blood consistent with the known mechanism of action were observed; most of which were considered not clinically significant. Only two cases (total WBC increased and eosinophilia) were reported as AEs. No development of anti-drug antibodies was observed.