Patients with vigorous and sustained responses to dexpramipexole. Blood absolute eosinophil counts (AECs) are shown by bold line and squares (patients 5 and 15) and triangles (patient 7). MED is minimum effective glucocorticoid dose that maintained the AEC <1000/μL and suppressed symptoms of the hypereosinophilic syndrome (determined before drug administration). Green shading is the glucocorticoid dose as a % baseline or MED. The dotted vertical line indicates the primary study time end point. Dexpramipexole administration is indicated by the horizontal line/arrow above the graph. GC, glucocorticoid; MED, minimum effective glucocorticoid (prednisone or equivalent) dose.