Evaluation of Safety and Efficacy of CTX001 in Pediatric Participants With Transfusion-Dependent β-Thalassemia (TDT)

This is a single-dose, open-label study in pediatric participants with TDT. The study will evaluate the safety and efficacy of autologous CRISPR-Cas9 modified CD34+ human hematopoietic stem and progenitor cells (hHSPCs) (CTX001).

Key Inclusion Criteria: * Diagnosis of TDT as defined by: * Documented homozygous or compound heterozygous β-thalassemia including β-thalassemia/hemoglobin E (HbE). Participants can be enrolled based on historical data, but a confirmation of the genotype using the study central laboratory will be required before busulfan conditioning * History of at least 100 mL/kilograms (kg)/year of packed RBC transfusions in the prior 24 months before signing of consent (or the last rescreening for patients going through repeat screening) or, for participants initiating transfusion therapy \1 alpha deletion, or alpha multiplications * Participants with sickle cell β-thalassemia variant * Clinically significant and active bacterial, viral, fungal, or parasitic infection as determined by the investigator Other protocol defined Inclusion/Exclusion criteria may apply.