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Enrolling by invitationNCT04208529Updated Aug 11, 2026

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

A Phase 3 interventional study of CTX001 in Beta-Thalassemia, Thalassemia and Sickle Cell Disease, sponsored by Vertex Pharmaceuticals Incorporated. Enrolling by invitation at 20 sites in 6 countries. Open to participants aged 2 Years and older. Per ClinicalTrials.gov, last updated 2026-08-11.

Sponsored by Vertex Pharmaceuticals Incorporated · Phase 3, Interventional, and Other

Phase
Phase 3
Study type
Interventional
Enrollment
160
Allocation
Not applicable
Ages
2 Years and older
Sex
All
01

Study 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 151 (NCT05329649) or 161(NCT05477563) (severe sickle cell disease [SCD] studies).

02

Conditions studied

  • Beta-Thalassemia
  • Thalassemia
  • Sickle Cell Disease
  • Hematologic Diseases
  • Hemoglobinopathies
  • Genetic Diseases, Inborn
  • Sickle Cell Anemia
03

In context

beta-Thalassemia

294 studies on the registry are indexed under beta-Thalassemia; 69 are open to participants now.

This study's planned enrollment of 160 is above the median of 40 across 208 interventional studies indexed under beta-Thalassemia.

Browse beta-Thalassemia studies →

Lead sponsor

Vertex Pharmaceuticals Incorporated is the lead sponsor of 249 studies on the registry; 17 are open to participants now.

Of its 106 completed or terminated interventional studies of FDA-regulated products, 53 (50%) have results posted.

Browse Vertex Pharmaceuticals Incorporated studies →

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
2 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

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

Exclusion criteria

Exclusion Criteria:

  • There are no exclusion criteria
Terms in these criteria, in plain language(1)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

05

Study design

Phase
Phase 3
Primary purpose
Other
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrollment
160 participants (estimated)

Study arms

  • Experimental
    CTX001

    All 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.

    Biological: CTX001

Interventions

  • BiologicalCTX001

    CTX001 infusion.

    Also known as: Exagamglogene autotemcel, Exa-cel

06

What researchers measure

Primary outcomes

  1. New malignancies

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

  2. New or worsening hematologic disorders

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

  3. All-cause mortality

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

  4. Serious adverse events (SAEs)

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

  5. CTX001-related adverse events (AEs)

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

Secondary outcomes

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

    Time frame: Up to 15 years post CTX001 infusion

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

    Time frame: Up to 15 years post CTX001 infusion

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

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: Up to 5 years post CTX001 infusion

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

    Time frame: 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)

    Time frame: 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

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

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

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: 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)

    Time frame: 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)

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: 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

    Time frame: Up to 15 years post CTX001 infusion

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

    Time frame: From baseline up to 15 years post CTX001 infusion

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

    Time frame: From baseline up to 15 years post CTX001 infusion

  29. SCD: Change from baseline in haptoglobin over time

    Time frame: From baseline up to 15 years post CTX001 infusion

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

    Time frame: From baseline up to 15 years post CTX001 infusion

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

    Time frame: 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)

    Time frame: 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

    Time frame: Up to 5 years post CTX001 infusion

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

    Time frame: Up to 5 years post CTX001 infusion

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

    Time frame: Up to 5 years post CTX001 infusion

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

    Time frame: Up to 5 years post CTX001 infusion

07

Study locations

20 sites
08

References and documents

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 ↗

Individual participant data

Plan to share: 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/

09

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reachedSimilar studies: half by the dot; the band is the middle halfHalf of similar studies reached it by the dot; the band is the middle half, from a quarter to three quarters

Started Jan 2021 (actual). Primary completion is estimated for Sep 2039, 224 months after the start.

Of 18 phase 3 interventional studies under beta-Thalassemia, half reached primary completion within 60 months of starting (the median), counting those still running; a quarter within 22 and three quarters within 67. This study's planned 224 months is above that.

How these figures are worked out, and which studies are left out of them.

Registered
Dec 20, 2019
First posted
Dec 23, 2019
StartActual
Jan 20, 2021
Primary completionEst.
Sep 30, 2039
CompletionEst.
Sep 30, 2039
Last update
Aug 11, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on Aug 11, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT04208529
Lead sponsor
Vertex Pharmaceuticals Incorporated
Collaborators
CRISPR Therapeutics
Responsible party
Sponsor
First posted
Dec 23, 2019
Start date
Jan 20, 2021
Primary completion
Sep 30, 2039 (estimated)
Completion
Sep 30, 2039 (estimated)
Last update
Aug 11, 2026

Oversight

FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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