A Phase 3b Study to Evaluate Efficacy and Safety of a Single Dose of Autologous CRISPR Cas9 Modified CD34+ Human Hematopoietic Stem and Progenitor Cells (CTX001) in Subjects With Transfusion-Dependent β-Thalassemia or Severe Sickle Cell Disease

About the study

This is a single-dose, open-label study in participants with transfusion-dependent β-thalassemia (TDT) or severe sickle cell disease (SCD). The study will evaluate the safety and efficacy of autologous CRISPR-Cas9 modified CD34+ human hematopoietic stem and progenitor cells (hHSPCs) using CTX001.

Study point of contact

Medical Information
[email protected]


12 Years - 35 Years


Phase 3

Study type






participation requirements

Participants with TDT and SCD:

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

Participants with TDT:

Diagnosis of TDT as defined by:

Documented homozygous β-thalassemia 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 milliliter (mL)/kilograms (kg)/year or 10 units/year of packed red blood cells (RBC) transfusions in the prior 2 years before signing the consent or the last rescreening for patients going through re-screening

Participants with SCD:

Diagnosis of severe SCD as defined by:

Documented SCD genotypes
History of at least two severe VOCs events per year for the previous two years prior to enrollment


participation restrictions

Participants with TDT and SCD:

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)
Clinically significant and active bacterial, viral, fungal, or parasitic infection as determined by the investigator

Participants with TDT:

Participants with associated α-thalassemia and >1 alpha deletion, or alpha multiplications
Participants with sickle cell β-thalassemia variant

Participants with SCD:

History of untreated moyamoya syndrome or presence of moyamoya syndrome at screening

Other protocol defined Inclusion/Exclusion criteria may apply.

Last updated 2023-01-24