One hundred subjects will receive study drug or matching placebo over 12 weeks of consecutive dosing. Following a short Run-in Period, eligible subjects will enter the Primary Assessment Period and receive twice-daily dosing of study drug or placebo for 12 weeks. Following 12 weeks of treatment, subjects will enter a 12-week Eosinophil Recovery Period. The primary endpoint for the study is the change in blood absolute eosinophil count from Baseline to Week 12.