Platelet counts of WAS/XLT patients (n = 8) during treatment with eltrombopag. Eltrombopag doses varied by patient and ranged from 9 mg to 75 mg daily. Patients were considered responders if at least one platelet count increased to ≥50 × 10⁹/L, was double the baseline count, and bleeding was reduced. The temporary rise in platelet count at week 6 to >160 × 10⁹/L in subject 10 (a nonresponder) was the result of a platelet transfusion (A). Five patients continued treatment past 52 weeks (B).