A Study to Evaluate Luspatercept (ACE-536) in Chinese Participants Who Require Regular Red Blood Cell Transfusions Due to Beta (β)-Thalassemia.

Inclusion Criteria:

• Participant is willing and able to adhere to the study visit schedule (for example,not scheduled to receive hematopoietic stem cell transplantation [HSCT]) and otherprotocol requirements.

• Participant has documented diagnosis of β-thalassemia or Hemoglobin E/β-thalassemia (β-thalassemia with mutation and/or multiplication of alpha (α) globin is allowed).

• Participant is regularly transfused, defined as: 6-25 RBC units in the 24 weeksprior to randomization and no transfusion-free period for >42 days during thatperiod.

• Participant has Eastern Cooperative Oncology Group (ECOG) score of 0 or 1.

Exclusion Criteria:

• Participant has a diagnosis of Hemoglobin S/β-thalassemia or α-thalassemia (forexample, Hemoglobin H).

• Participant has active hepatitis C virus (HCV) infection as demonstrated by apositive HCVribonucleic acid (RNA) test of sufficient sensitivity, or activeinfectious hepatitis B virus (HBV) as demonstrated by the presence of hepatitis Bsurface antigen (HBsAg) and/or HBVdeoxyribonucleic acid (DNA) positive, or knownpositive human immunodeficiency virus (HIV).

• Participant has a history of deep venous thrombosis or stroke or thromboembolicevents (venous or arterial) requiring medical intervention ≤24 weeks prior torandomization.

• Participant uses chronic anticoagulant therapy, unless the treatment stopped atleast 28 days prior to randomization. Anticoagulant therapies used for prophylaxisfor surgery or high-risk procedures as well as low-molecular-weight heparin forsuperficial venous thrombosis and chronic aspirin are allowed.

• Participant who has EMH complications requiring treatment to control the growth ofEMH mass(es) during the screening period.

• Participant used immunomodulatory imide drugs (IMiDs) ≤ 24 weeks prior torandomization