Adults with transfusion-dependent beta-thalassemia (n= 336).
Luspatercept (at a dose of 1.00 to 1.25 mg per kilogram of body weight) for at least 48 weeks (n=224).
Placebo for at least 48 weeks (n= 112).
The percentage of patients who had a reduction in the transfusion burden of at least 33% from baseline during weeks 13 through 24 plus a reduction of at least 2 red-cell units over this 12-week interval was significantly greater in the luspatercept group than in the placebo group (21.4% vs. 4.5%). During any 12-week interval, the percentage of patients who had a reduction in transfusion burden of at least 33% was greater in the luspatercept group than in the placebo group, as was the percentage of those who had a reduction of at least 50%. The least-squares mean difference between the groups in serum ferritin levels at week 48 was -348 mug per liter in favor of luspatercept. Adverse events of transient bone pain, arthralgia, dizziness, hypertension, and hyperuricemia were more common with luspatercept than placebo.