A SAD/MAD to Assess the Safety, PK/PD of FT-4202 in Healthy Volunteers and Sickle Cell Disease Patients

SCD Key Inclusion Criteria: * Must be between 12 and 65 years of age * Previously diagnosed sickle cell disease (hemoglobin electrophoresis or genotype) * Must have a minimum body weight of 40 kg (88 lbs) at the Screening Visit * Must have the ability to understand and sign written informed consent (and assent where applicable), which must be obtained prior to any study-related procedures being completed * All male and female patients of child bearing potential must agree to use medically accepted contraceptive regimen during study participation and for 90 days after last study drug administration * Must be willing to abide by all study requirements and restrictions SCD Key Exclusion Criteria: * Had more than 6 episodes of vaso-occlusive crisis (VOC) within the past 12 months that required a hospital, emergency room, or clinic visit * Had a least one episode of acute chest syndrome in the last 6 months * Received any of the following approved therapies for use in SCD: * Hydroxurea (HU): excluded if started HU \< 90 days prior to Day 1 of study treatment * Adakveo®: excluded if received an infusion within 14 days prior to Day 1 of study treatment * Oxbryta®: excluded if received a dose within 7 days prior to start of Day 1 of study treatment * Received a red blood cell transfusion within 30 days of starting the study drug * Hemoglobin \< 7.0 g/dL or \> 10.5 g/dL * Unable to take and absorb oral medications HEALTHY VOLUNTEER Inclusion Criteria: \[Note: no longer recruiting subjects for this portion of the study\] * Subjects must be between 18 and 60 years of age * Subjects must have the ability to understand and sign written informed consent, which must be obtained prior to any study-related procedures being completed * Subjects must be in general good health, based upon the results of medical history, a physical examination, vital signs, laboratory profile, and a 12-lead ECG * All males and females of child bearing potential must agree to use medically accepted contraceptive regimen during study participation and up to 90 days after * Subjects must be willing to abide by all study requirements and restrictions HEALTHY VOLUNTEER Exclusion Criteria: \[Note: no longer recruiting subjects for this portion of the study\] * Evidence of clinically significant medical condition or other condition that might significantly interfere with the absorption, distribution, metabolism, or excretion of study drug, or place the subject at an unacceptable risk as a participant in this study * History of clinically significant cardiac diseases including condition disturbances * Abnormal hematologic, renal and liver function studies * History of drug or alcohol abuse