The purpose of this study is to evaluate whether fostamatinib is safe and effective in the treatment of Warm Antibody Autoimmune Hemolytic Anemia (AIHA).

Inclusion Criteria:

Subject must have had a diagnosis of primary or secondary warm antibody AIHA.

- Must have failed at least 1 prior treatment regimen for AIHA.

Exclusion Criteria:

• Subject with cold antibody AIHA, cold agglutinin syndrome, mixed type AIHA, or paroxysmal cold hemoglobinuria.
• Subject with a platelet count of < 30,000/μL.
• Subject has AIHA secondary to autoimmune disease, including systemic lupus erythematosis (SLE), or lymphoid malignancy and the underlying disease is not stable or is not well-controlled on current therapy.
• Subject has uncontrolled or poorly controlled hypertension, defined as systolic blood pressure ≥ 130 mmHg, or diastolic blood pressure ≥ 80 mmHg.