NCT05477563 · Vertex Pharmaceuticals Incorporated
Evaluation of Efficacy and Safety of a Single Dose of CTX001 in Participants With Transfusion-Dependent β-Thalassemia and Severe Sickle Cell Disease
What this study is about
This is a single-dose, where both patients and doctors know the treatment given study in participants with transfusion-dependent β-thalassemia (TDT) or severe sickle cell disease (SCD). The study will evaluate the safety and effectiveness of autologous CRISPR-Cas9 modified CD34+ human hematopoietic stem and progenitor cells (hHSPCs) using CTX001.
View original scientific description
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.
Interventions
BIOLOGICAL
CTX001
Administered by intravenous (IV) infusion following myeloablative conditioning with busulfan
Primary outcome measures
Fetal Hemoglobin (HbF) Concentration Over Time
Time frame: Up to 12 Months After CTX001 Infusion
Total Hemoglobin (Hb) Concentration Over Time
Time frame: Up to 12 Months After CTX001 Infusion
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- 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 Key
Exclusion criteria
- Participants with TDT and SCD:
- A willing and healthy
Where
- New York, New York
- Charlotte, North Carolina
- Nashville, Tennessee
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Mar 23, 2026 · Source of record for eligibility and locations