A study to evaluate the amount of fostamatinib in the blood in subjects with impaired hepatic (liver) function compared with healthy volunteers with normal liver function. The study will also evaluate safety and tolerability in subjects with hepatic impairment.

Inclusion Criteria:

• Males and females (non child-bearing potential) aged 18 years or more, with a weight of at least 50 kg and body mass index (BMI) between 18 and 40 kg/m2 inclusive
• Healthy subjects only: good health as determined by a medical history, physical examination , ECG and clinical laboratory evaluations
• Healthy subjects only: negative results for serum hepatitis B and C

Exclusion Criteria:

• Subjects who have received any medications known to alter drug absorption or elimination within 30 days of first dose.
• Subjects who smoke more than 10 cigarettes or equivalent per day
• Absolute neutrophil count <2500/mm3
• Abnormal vital signs, additional systemic disease (eg, cardiac, or renal disease) or abnormal laboratory findings that are judged to be clinically significant by the investigator
• Healthy volunteers only: use of prescribed medications within 2 weeks of first dose or use of non-prescribed medications within 1 week of first dose
• Hepatic subjects only: fluctuating or rapidly deteriorating hepatic function