Figure 1.

Flowchart of study design

(A) During the first phase of the study, 20 patients with asthma were enrolled. At day 0, all patients were labeled with deuterium glucose and baseline blood sample was withdrawn. Thereafter, patients were randomized in a blinded fashion for treatment with mepolizumab (n = 10) or placebo (n = 10). In both groups, only blood (red arrows) or blood and sputum (green arrows) samples were taken on different days, starting from day 4 after label intake. The first phase ended at day 60 after label intake. Mepolizumab or placebo was administered for the first time at day 4 after label intake. This was followed by the second and third administration of mepolizumab or placebo, each time 28 days later (at day 32 or 60, respectively).

(B) The second phase started at 84 days after the first label intake. At this day, all patients were again labeled with deuterium glucose and blood was withdrawn. Four days after the second label intake, the fourth and last mepolizumab or placebo dose was administered. Again either blood only (red arrows) or blood and sputum (green arrows) were taken on several following days.