Mean (± 95% CI) change in hemoglobin level relative to baseline. (A) Non–transfusion-dependent patients with β-thalassemia treated with luspatercept at 0.2 to 0.4 mg/kg compared with 0.6 to 1.25 mg/kg during the initial stage of the study. (B) All non–transfusion-dependent patients with β-thalassemia treated with luspatercept at 0.6 to 1.25 mg/kg during the initial and/or extension stage of the study.