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

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 <24 months before signing of consent, requirement for packed RBC
transfusion at least every 3 to 4 weeks for ≥6 months

- Eligible for autologous stem cell transplant as per investigator's judgment.

Key Exclusion Criteria:

- A willing and healthy 10/10 human leukocyte antigen (HLA)-matched related donor is
available per investigator's judgement

- Prior hematopoietic stem cell transplant (HSCT)

- Participants with associated α-thalassemia and >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.