Safety Study for Beta Thalassemia Subjects on PTG-300

The PTG-300-03 study will study beta thalassemia patients on PTG-300 for two years. The dose and dose frequency for each subject enrolling in the PTG-300-03 study will be based on the last dose and frequency received by the subject in the previous study PTG-300-02 and the subject's response at that dose. Patients dose will be increased in a manner similar to that used on PTG-300-02 study. The maximum PTG-300 dose allowed is 80 mg/week.