Platelet response over months of fostamatinib therapy. Patients in a–c (cases 1–3) were managed with fostamatinib for at least 1 year, with ≥8 months of platelet counts available within that first year. Three months of platelet counts were available for the patient in d (case 4), and 4 months for the patient in e (case 5), during which he received rescue therapy with IVIg in months 1, 2, and 3. BL, baseline; IVIg, intravenous immunoglobulin.