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Beta-ThalassemiaPhase 3NCT04208529

A Long-term Follow-up Study in Participants Who Received CTX001

A Phase 3 study testing CTX001 in people with Beta-Thalassemia and Thalassemia, run by Vertex Pharmaceuticals Incorporated at 20 sites in 6 countries.

Enrolling by invitation

Enrolling by invitation. The study team selects and invites participants, usually from an existing group of patients.

Sites and contacts
Official record
Search all trials

Trial summary

This is a multi-site, open- label rollover study to evaluate the long-term safety and efficacy of CTX001 in pediatric and adult participants who received CTX001 in parent studies 111 (NCT03655678) 141 (NCT05356195) or 161 (NCT05477563) (transfusion-dependent β-thalassemia [TDT] studies) or Study 121 (NCT03745287) or… Read more about this study

Who is it for?
Ages 2 years and older
Conditions the study is for
Beta-Thalassemia, Thalassemia, Sickle Cell Disease
What is being tested?
CTX001
Type of treatment
Injection or infusion
Could I receive a placebo?
No, everyone receives an active treatment
How many people
160 participants
Where
20 sitesin 6 countries
Study dates
20 Jan 2021to 30 Sep 2039
Phase
Phase 3
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 2 years and older
  • All sexes
  • No healthy volunteers
  • Child, Adult, Older adult

Who may be able to join

  • Participants (or his or her legally appointed and authorized representative or guardian) must sign and date informed consent form (ICF) and, where applicable, an assent form
  • Participants must have received CTX001 infusion in a parent study

Who cannot join

  • There are no exclusion criteria

Trial locations and contacts

20 sites in 6 countries. Contact the study team or a site near you to ask about taking part.

20 sites in 6 countries

United States9 sites

  • Levine Children's Hospital - Hematology

    Charlotte, North Carolina, 28203

  • Ann & Robert H. Lurie Children's Hospital of Chicago - Hematology

    Chicago, Illinois, 60611

  • St. Jude Children's Research Hospital

    Memphis, Tennessee, 38105

  • TriStar Medical Group Children's Specialists - Pediatric Oncology

    Nashville, Tennessee, 37203

  • Herbert Irving Pavilion - Hematology

    New York, New York, 10032

  • New York Presbyterian Hospital - Morgan Stanley Children's Hospital

    New York, New York, 10032

  • Lucile Packard Children's Hospital

    Palo Alto, California, 94304

  • The Children's Hospital of Philadelphia - Hematology

    Philadelphia, Pennsylvania, 19104

  • Methodist Healthcare System of San Antonio, Methodist Hospital, Methodist Children's Hospital

    San Antonio, Texas, 78229

Other trials in United States

Canada3 sites

  • Hospital for Sick Children - Hematology

    Toronto

  • Toronto General Hospital - Hematology

    Toronto

  • St. Paul's Hospital - Hematology

    Vancouver

Other trials in Canada

Germany3 sites

  • University Hospital Duesseldorf - Department of Pediatric Oncology, Hematology and Clinical Immunology

    Düsseldorf

  • Center for Pediatric Clinical Studies (CPCS)

    Klinik Für Kinder- Und Jugendmedizin

  • Regensburg University Hospital, Clinic and Polyclinic for Paediatric and Adolescent Medicine

    Regensburg

Other trials in Germany

United Kingdom3 sites

  • Great Ormond Street Hospital for Children

    London

  • Hammersmith Hospital - Haematology Dept

    London

  • University College London Hospital NHS Foundation - Main

    London

Other trials in United Kingdom

Belgium1 site

  • Hopital Universitaire des Enfants Reine Fabiola (HUDERF) - Hematology

    Brussels

Other trials in Belgium

Italy1 site

  • IRCSS Ospedale Pediatrico Bambino Gesu - Dipartimento di Onco-Ematologia e Terapia Cellulare e Genica

    Rome

Other trials in Italy

About this study

Official title: A Long-term Follow-up Study of Subjects With β-thalassemia or Sickle Cell Disease Treated With Autologous CRISPR-Cas9 Modified Hematopoietic Stem Cells (CTX001)

This is a multi-site, open- label rollover study to evaluate the long-term safety and efficacy of CTX001 in pediatric and adult participants who received CTX001 in parent studies 111 (NCT03655678) 141 (NCT05356195) or 161 (NCT05477563) (transfusion-dependent β-thalassemia [TDT] studies) or Study 121 (NCT03745287) or 151 (NCT05329649) or 161(NCT05477563) (severe sickle cell disease [SCD] studies).

Being tested
CTX001
Medical subject headings
beta-Thalassemia, Thalassemia, Anemia, Sickle Cell, Hematologic Diseases, Hemoglobinopathies, Genetic Diseases, Inborn

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • CTX001Biological

    Also called Exagamglogene autotemcel, Exa-cel

    CTX001 infusion.

Study groups in NCT04208529
Study groupRoleWhat they receive
CTX001ExperimentalAll participants who complete or discontinue one of the multiple parent studies (CTX001-111, CTX001-121, CTX001-141, CTX001-151 and CTX001-161) after CTX001 infusion will be asked to participate in this long-term follow-up study.
Receives: Biological: CTX001

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. New malignancies

    Measured: Signing of informed consent up to 15 years post CTX001 infusion

  2. New or worsening hematologic disorders

    Measured: Signing of informed consent up to 15 years post CTX001 infusion

  3. All-cause mortality

    Measured: Signing of informed consent up to 15 years post CTX001 infusion

  4. Serious adverse events (SAEs)

    Measured: Signing of informed consent up to 15 years post CTX001 infusion

  5. CTX001-related adverse events (AEs)

    Measured: Signing of informed consent up to 15 years post CTX001 infusion

Secondary outcomes (36)

  1. TDT and SCD: Total Hemoglobin (Hb) concentration over time

    Measured: Up to 15 years post CTX001 infusion

  2. TDT and SCD: Fetal Hemoglobin (HbF) concentration over time

    Measured: Up to 15 years post CTX001 infusion

  3. TDT and SCD: Proportion of alleles with intended genetic modification present in peripheral blood over time

    Measured: Up to 15 years post CTX001 infusion

  4. TDT and SCD: Proportion of alleles with intended genetic modification present in CD34+ cells of the bone marrow over time

    Measured: Up to 15 years post CTX001 infusion

  5. TDT and SCD: Change in patient-reported outcome (PRO) over time in participants ≥18 years of age assessed using EuroQol quality of life scale (EQ-5D-5L) for participants from study 111 and 121 only

    Measured: Up to 5 years post CTX001 infusion

  6. TDT and SCD: Change in PROs over time in participants ≥18 years of age assessed using functional assessment of cancer therapy-bone marrow transplant (FACT-BMT) questionnaire for participants from study 111, 121 and 161 only

    Measured: Up to 5 years post CTX001 infusion

  7. TDT and SCD: Change in PROs over time in participants <18 years assessed using EQ-5D-Youth (EQ-5D-Y) from study 111,121,141 and 151 only

    Measured: Up to 5 years post CTX001 infusion

  8. TDT and SCD: Change in PROs over time in participants <18 years assessed using pediatric quality of life inventory (PedsQL) Core

    Measured: Up to 5 years post CTX001 infusion

  9. TDT: Proportion of participants achieving transfusion independence for at least 12 consecutive months (TI12)

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  10. TDT: Proportion of participants achieving transfusion independence for at least 6 consecutive months (TI6)

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  11. TDT: Proportion of participants achieving at least 95%, 90%, 85%, 75%, 50% reduction from baseline in annualized volume of RBC transfusions starting after month 10 after CTX001 infusion for participants who have not achieved TI12

    Measured: From Month 10 up to 15 years post-CTX001 infusion

  12. TDT: Duration of transfusion free in participants who have achieved TI12

    Measured: From 60 days after last RBC transfusion up to 15 years post CTX001 infusion

  13. TDT: Relative reduction from baseline in annualized volume of RBC transfusions starting after Month 10 after CTX001 infusion for participants who have not achieved TI12

    Measured: From Month 10 up to 15 years post-CTX001 infusion

  14. TDT: Iron overload as measured by liver iron concentration (LIC), cardiac iron concentration (CIC), and ferritin for beta-Thalassemia participants

    Measured: Up to 8 years post CTX001 infusion for LIC; up to 5 years post CTX001 infusion for CIC and up to 15 years post CTX001 infusion for ferritin

  15. TDT: Proportion of participants receiving iron removal therapy over time

    Measured: Up to 15 years post CTX001 infusion

  16. SCD: Proportion of participants who have not experienced any severe vaso-occlusive crises (VOC) for at least 12 consecutive months (VF12)

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  17. SCD: Proportion of participants with SCD free from inpatient hospitalization for severe VOCs sustained for at least 12 months (HF12)

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  18. SCD: Proportion of participants with at least 90 percent (%), 80%, 75% or 50% reduction in annualized rate of severe VOCs

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  19. SCD: Relative change from baseline in annualized rate of severe VOCs

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  20. SCD: Duration of severe VOC free in participants who have achieved VF12

    Measured: From 60 days after last RBC transfusion up to 15 years post CTX001 infusion

  21. SCD: Relative change from baseline in rate of inpatient hospitalizations for severe VOCs

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  22. SCD: Relative change from baseline in annualized duration of hospitalization for severe VOCs

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  23. SCD: Proportion of participants with sustained HbF ≥20% for at least 3 months

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  24. SCD: Proportion of participants with sustained HbF ≥20% for at least 6 months

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  25. SCD: Proportion of participants with sustained HbF ≥20% for at least 12 months

    Measured: From 60 days after last RBC transfusion up to 15 years post-CTX001 infusion

  26. SCD: Change in volume of RBCs transfused for SCD-related indications over time

    Measured: Up to 15 years post CTX001 infusion

  27. SCD: Change from baseline in reticulocytes/erythrocytes over time

    Measured: From baseline up to 15 years post CTX001 infusion

  28. SCD: Change from baseline in lactate dehydrogenase (LDH) over time

    Measured: From baseline up to 15 years post CTX001 infusion

  29. SCD: Change from baseline in haptoglobin over time

    Measured: From baseline up to 15 years post CTX001 infusion

  30. SCD: Change from baseline in total bilirubin over time

    Measured: From baseline up to 15 years post CTX001 infusion

  31. SCD: Change from baseline in indirect bilirubin over time

    Measured: From baseline up to 15 years post CTX001 infusion

  32. SCD: Change in SCD-specific PROs over time in participants ≥18 years of age assessed using adult sickle cell quality of life measurement system (ASCQ-Me) (participants from Study 121 and 161 only)

    Measured: Up to 5 years post CTX001 infusion

  33. SCD: Change in SCD-specific PROs over time in participants <18 years of age assessed using PedsQL Generic Core SCD module from studies 111,121,141,151 and 161

    Measured: Up to 5 years post CTX001 infusion

  34. SCD: Change in PRO over time assessed using 11-point numerical rating scale (NRS)

    Measured: Up to 5 years post CTX001 infusion

  35. SCD: Change in PROs over time assessed using Wong Baker FACES pain scale

    Measured: Up to 5 years post CTX001 infusion

  36. SCD: Change in PROs over time using face, legs, activity, cry, consolability (FLACC) behavioral pain scale

    Measured: Up to 5 years post CTX001 infusion

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted23 Dec 2019
  2. Study start20 Jan 2021
  3. Primary completion30 Sep 2039 (estimated)
  4. Study completion30 Sep 2039 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Other
Allocation
Not applicable
Intervention model
Single group
Model description
Long Term Safety Follow-up
Masking
None (open label)
Enrolment
160 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04208529
Sponsor's protocol ID
VX18-CTX001-131
Other IDs
2024-512654-19-00
Status last verified
Aug 2026
First submitted
20 Dec 2019
Last updated
11 Aug 2026
Results posted
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
No: Details on Vertex data sharing criteria and process for requesting access can be found at: https://www.vrtx.com/our-science/clinical-trials-data-sharing/

Publications

  • Sheth S, Corbacioglu S, de la Fuente J, Algeri M, Rupprecht J, Kuo KHM, Shah AJ, Lang P, Merkeley H, Carpenter B, Mapara MY, Liem RI, Grupp S, Chopra Y, Li AM, Kwiatkowski JL, Kirby-Allen M, Cappellini MD, Kattamis A, Zairis S, Liu T, Hobbs W, Frangoul H, Locatelli F, Meisel R; CLIMB THAL-111 and CLIMB-131 Study Groups. Correction of Ineffective Erythropoiesis and Normalization of Iron Homeostasis After Exagamglogene Autotemcel in Transfusion-Dependent beta-Thalassemia. Am J Hematol. 2026 Aug;101(8):1969-1979. doi: 10.1002/ajh.70382. Epub 2026 Jun 7.

    PubMed 42252696

  • Fuente J, Frangoul H, Lang P, Wall D, Meisel R, Corbacioglu S, Li AM, Shah AJ, Carpenter B, Kwiatkowski JL, Mapara MY, Liem RI, Rupprecht J, Kuo KHM, Merkeley H, Algeri M, Smith W, Kohli P, Li N, Rubin J, Zhang S, Hobbs W, Locatelli F. Improvements in health-related quality of life in patients with transfusion-dependent beta-thalassemia after exagamglogene autotemcel. Blood Adv. 2025 Dec 23;9(24):6502-6510. doi: 10.1182/bloodadvances.2025016702.

    PubMed 40862696

  • Sharma A, Locatelli F, Bhatia M, Molinari L, Mapara MY, Liem RI, Dedeken L, Wall D, Eckrich MJ, Kuo KHM, Smith W, Imren S, Kohli P, Li N, Liu T, Rubin J, Hobbs W, Grupp SA, Frangoul H. Improvements in health-related quality of life in patients with severe sickle cell disease after exagamglogene autotemcel. Blood Adv. 2025 Dec 23;9(24):6481-6490. doi: 10.1182/bloodadvances.2025016701.

    PubMed 40857358

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing CTX001 in people with Beta-Thalassemia and Thalassemia, run by Vertex Pharmaceuticals Incorporated at 20 sites in 6 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 2 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: enrolling by invitation, as of the sponsor's last update on 11 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 20 sites in United States, Canada, Germany, United Kingdom, Belgium and 1 more country. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

New malignancies (time frame: Signing of informed consent up to 15 years post CTX001 infusion). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04208529, which also lists 3 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Aug 2026.

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