Changes in renal function parameters.

The purpose of this study is to assess safety and amount of the study drug in the blood after increasing doses of SP-420. The study will be conducted in patients with β-thalassemia.

Inclusion Criteria:

• Subject has iron-overload secondary to β-thalassemia requiring chronic red blood cell transfusions and iron chelation therapy
• Subject weighs ≥35 kg
• Subject is willing to discontinue current iron chelation therapy at least 7 days prior to the first dose of SP-420 and for the duration of the study
• Serum ferritin ≥700 ng/mL and iron saturation ≥70% within 3 weeks before Baseline (Day 1)
• Cardiac T2* score >20 msec within 6 months before Baseline (Day 1)
• Willing to use contraception during the study

Exclusion Criteria:

• Pregnant or breast-feeding
• Serum creatinine greater than the upper limit of normal
• Platelet count <100 × 10^9/L
• Use of another investigational drug within the last 30 days
• Significant cardiac, renal, hepatic dysfunction or other clinically significant conditions that, in the opinion of the Investigator, would exclude the subject