A 2 stage study to evaluate the amount of fostamatinib in the blood and urine in subjects with impaired kidney (renal) function compared with healthy volunteers with normal renal function. Stage 1 will include healthy subjects and subjects with end stage renal disease, while Stage, 2 may include subjects with mild, moderate and/or severe renal impairment dependent on the outcome of Stage 1. The study will also evaluate safety and tolerability in subjects with renal impairment.

Inclusion Criteria:

• Males or females (non child bearing potential) greater than or equal to 18 years of age with suitable veins for cannulation or repeated venipuncture and with a weight of at least 50 kg (110 lbs) and body mass index (BMI) between 18 and 40 kg/m2, inclusive
• Stable renal impairment with following creatinine clearance (CLCR): Stage 1 - End Stage Renal Disease (ESRD) < 15 mL/min (requiring dialysis); Stage 2 - Mild renal impairment ≥ 50 to < 80 mL/min; Moderate renal impairment ≥ 30 to <50 mL/min; and severe renal impairment 15 to < 30 mL/min
• Healthy subjects with normal renal function must have good health based on medical history, physical examination , echocardiogram and clinical laboratory evaluations including creatinine clearance >80 ml/min"
• Negative screen for Human Immunodeficiency Virus and negative results for serum hepatitis B surface antigen and hepatitis C antibody

Exclusion Criteria:

• Subjects who have received any medications known to chronically alter drug absorption or elimination processes within 30 days of the first dose administration
• Absolute neutrophil count less than 1600/mm3 or 1.6 x 109 L.
• Healthy subjects only: Subjects who have received any prescribed systemic or topical medication within 14 days of the first dose administration
• Subjects with a history of multiple drug allergies or with a known allergy to the drug class of fostamatinib
• In the opinion of the Investigator, any evidence of additional severe or uncontrolled systemic disease (eg, currently unstable or uncompensated hepatic, cardiovascular, or respiratory disease) or laboratory finding