Inclusion Criteria:

• Clinical diagnosis of beta thalassemia intermedia or hemoglobin E beta thalassemia
• Steady-state hemoglobin level less than 10 g/dL
• Age ≥ 12 and ≤ 45 years
• Able and willing to give informed consent or assent (if less than 18 years of age) and comply with all study procedures
• If female and of childbearing potential, must have a documented negative pregnancy test at Day -1 and must agree to use one or more locally medically accepted methods of contraception in the month prior to randomization, through the entire study, and for 4 weeks after the last dosing of study medication
• If male and partner is of childbearing potential, must agree to use one or more locally medically accepted methods of birth control for themselves and their partner in the month prior to randomization, through the entire study, and for 4 weeks after the last dosing of study medication

Exclusion Criteria:

• Spleen palpable >2 cm below the left costal margin
• Pulmonary hypertension requiring oxygen therapy
• QTc > 450 msec on screening ECG
• Diagnosis of hepatitis C, hepatitis B or HIV and receiving treatment within 1 month prior to study drug administration
• Red blood cell (RBC) transfusions within 3 months prior to administration of study medication
• Fever greater than 38.5°C in the week prior to administration of study medication
• ALT > 3x upper limit of normal (ULN)
• Baseline elevation of CPK value prior to randomization
• Treatment with hydroxyurea within 2 months prior to administration of study medication
• Cancer diagnosis within 5 years of randomization (except for non-melanoma cutaneous malignancies)
• Serum creatinine > 1.5 mg/dl
• Received investigational systemic therapy within 6 weeks prior to randomization
• Currently pregnant or breast feeding a child
• Sexually active without contraception
• Subject history of wide complex tachyarrhythmias or resuscitation from sudden death