A Study of the Safety, Blood Levels and Biological Effects of GBT440 in Healthy Subjects and Subjects With Sickle Cell Disease

Inclusion Criteria: * Healthy male or female of non-child bearing potential; 18 to 55 years old; are non-smokers and have not used nicotine products within 3 months prior to screening. * Male or female, 18 to 60 years old, with sickle cell disease (hemoglobin SS, HbS/β0thalassemia, HbS/β+thalassemia, or HbSC) not requiring chronic blood transfusion therapy; without hospitalization in 30 days before screening or receiving blood transfusion within 30 days before screening; subjects are allowed concomitant use of hydroxyurea if the dose has been stable for the 3 months prior to screening. Exclusion Criteria: * Subjects who have a clinically relevant history or presence of respiratory, gastrointestinal, renal, hepatic, haematological, lymphatic, neurological, cardiovascular, psychiatric, musculoskeletal, genitourinary, immunological, dermatological, connective tissue diseases or disorders. * Subjects who consume more than 14 (female subjects) or 21 (male subjects) units of alcohol a week. * Subjects who have used any investigational product in any clinical trial within 30 days of screening * Subjects with sickle cell disease who smoke \>10 cigarettes per day; have hemoglobin level \<6 g/dL or \>10.4 g/dL (\> ULN (appropriately corrected for gender) for Cohort 15) at screening; have aspartate aminotransferase (AST) \>4x upper limit of normal or alanine aminotransferase (ALT), or alkaline phosphatase (ALK) \>3x upper limit of normal reference range (ULN) at screening; have moderate or severe renal dysfunction