Single-Dose PK Study of GBT440 in Subjects With Renal Impairment

Up to 40 adult subjects will be enrolled. Safety and PK assessments will be performed at
selected time points throughout the study.

Inclusion Criteria:

All subjects:

- Males or females, 18 to 80 years old

- Willing and able to give written informed consent

Subjects with renal impairment:

- Severe renal impairment (eGFR < 30 mL/min/1.73m2, not on dialysis)

- Moderate renal impairment (30 mL/min/1.73m2 = or < eGFR < 60 mL/min/1.73m2)

- Mild renal impairment (60 mL/min/1.73m2 = or < eGFR < 90 mL/min/1.73m2)

Healthy subjects:

- Match in age, gender and body mass index with renal impaired subjects

- Healthy and without clinically significant abnormalities in vital signs, ECGs,
physical exam, clinical laboratory evaluations, medical and surgical history

Exclusion Criteria:

All subjects:

- Participation in another clinical trial of an investigational drug (or medical device)
within 30 days of the last dose of investigational drug or 5 half lives whichever is
longer, prior to screening, or is currently participating in another trial of an
investigational drug (or medical device)

- Any signs or symptoms of acute illness at screening or Day -1

- History or presence of clinically significant allergic, hematological, endocrine,
pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, or neurological
disease

Subjects with renal impairment:

- History of clinically significant hepatic disease e.g. hepatitis, cirrhosis and or liver
enzymes (ALT, AST, GGT and total bilirubin) > 5 times the upper limit of normal within the
past year