This is a Phase 1 multicenter, open-label study evaluating the safety, tolerability, pharmacokinetics (PK), fetal hemoglobin (HbF) induction and biological activity of FTX-6058 in subjects 18-65 years of age, inclusive with sickle cell disease (SCD).~This study will comprise 2 parts and will be conducted in subjects 18-65 years of age, inclusive with sickle cell disease (SCD) either taking hydroxyurea (HU) at a stable dose for at least the preceding 3 months, or not taking hydroxyurea (HU).~Part A, the main study will consist of two phases. Cohort one will receive 6 mg of FTX-6058 by mouth once daily for 4 weeks. Second cohort may receive up to and including 20 mg of FTX-6058 by mouth once daily for 4 weeks depending on the Data Monitoring Committee [DMC] review. Up to three additional cohorts (up to five total cohorts) may be added based on the safety and pharmacokinetic data observed in subjects from the prior and ongoing cohorts. Up to 10 subjects will be enrolled in each treatment arm.~Part B is the extension study. Eligible subjects who consent to continue in the extension study will continue on treatment at the same dose level selected in Part A for an additional 8 weeks. Subjects who decline to participate in the extension study will be followed for an additional 2-3 weeks.~The primary endpoints of the study are to evaluate the safety and tolerability of FTX-6058 as measured by the frequency of adverse events and to evaluate single and multiple-dose pharmacokinetics of FTX-6058 in subjects with sickle cell disease. Secondary endpoints include evaluating the effect of FTX-6058 on fetal hemoglobin induction in peripheral blood in subjects with sickle cell disease.
This is a study to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of FTX-6058 in subjects with sickle cell disease.