Safety Study for Beta Thalassemia Subjects on PTG-300

An Open Label Extension Study of PTG-300 In Non-Transfusion Depenent (NTD) and Trasfusion-Dependent (TD) B-Thalassemia Subjects

In this study will investigate long term safety and use of the PTG-300 in Beta Thalassemia patients.

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.

Inclusion Criteria:

• NTD and TD β-thalassemia subjects who completed Week 12 and Week 16 respectively in Study PTG-300-02.

Exclusion Criteria:

• Subjects who discontinued prematurely from study 300-02 (before Week 12 in NTD and Week 16 in TD).