This is a three-part, multicenter, Phase 2/3 study of orally administered GBT021601 in participants with sickle cell disease (SCD). Part A will evaluate the safety, tolerability, and efficacy of GBT021601 in adult participants with SCD to determine an optimal dose. Part B will evaluate the efficacy of GBT021601 versus placebo in adult and pediatric participants with SCD for 48 weeks. Part C will evaluate the pharmacokinetics (PK) and safety of single and multiple doses (MD) of open-label single arm GBT021601 administered to pediatric participants.
The purpose of this study is to evaluate the safety, tolerability, efficacy, pharmacokinetics and pharmacodynamics of GBT021601.