Sickle Cell DiseasePhase 2/3NCT03745287
A Safety and Efficacy Study Evaluating CTX001 in Subjects With Severe Sickle Cell Disease
A Phase 2/3 study testing Exa-cel in people with Sickle Cell Disease and Hematological Diseases, run by Vertex Pharmaceuticals Incorporated at 17 sites in 7 countries.
Trial summary
This is a single-arm, open-label, multi-site, single-dose Phase 1/2/3 study in participants with 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. Read more about this study
- Who is it for?
- Ages 12 to 35 years
- Conditions the study is for
- Sickle Cell Disease, Hematological Diseases, Hemoglobinopathies
- What is being tested?
- Exa-cel
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 63 participants
- Where
- 17 sitesin 7 countries
- Study dates
- 27 Nov 2018to 7 Jul 2025
- Phase
- Phase 2/3
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 12 to 35 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- Diagnosis of severe sickle cell disease as defined by:
- Documented severe sickle cell disease genotype
- History of at least two severe vaso-occlusive crisis events per year for the previous two years prior to enrollment
- Eligible for autologous stem cell transplant as per investigators judgment
Who cannot join
- An available 10/10 human leukocyte antigen (HLA)-matched related donor
- Prior hematopoietic stem cell transplant (HSCT)
- Clinically significant and active bacterial, viral, fungal, or parasitic infection
- Other protocol defined inclusion/exclusion criteria may apply.
Trial locations and contacts
17 sites in 7 countries.
17 sites in 7 countries
United States9 sites
Ann & Robert Lurie Children's Hospital of Chicago
Chicago, Illinois, 60611
University of Illinois at Chicago Hospitals and Health Systems
Chicago, Illinois, 60612
St. Jude Children's Research Hospital
Memphis, Tennessee, 38105
The Children's Hospital at TriStar Centennial Medical Center/ Sarah Cannon Center for Blood Cancers
Nashville, Tennessee, 37203
Columbia University Medical Center (21+ years)
New York, New York, 10032
Columbia University Medical Center (≤21 years)
New York, New York, 10032
Lucile Packard Children's Hospital of Stanford University
Palo Alto, California, 94304
Children's Hospital of Philadelphia
Philadelphia, Pennsylvania, 19104
Methodist Children's Hospital/Texas Transplant Institute
San Antonio, Texas, 78229
Germany2 sites
University Hospital Duesseldorf
Düsseldorf
Regensburg University Hospital, Clinic and Polyclinic for Paediatric and Adolescent Medicine, Paediatric Haemotology, Oncology and Stem Cell Transplantation
Regensburg
United Kingdom2 sites
Imperial College Healthcare NHS Trust, Hammersmith Hospital
London
Royal London and St Bartholomew's Hospital, Pathology and Pharmacy Building
London
Belgium1 site
Hopital Universitaire des Enfants Reine Fabiola (HUDERF)
Brussels
Italy1 site
Dipartimento di Onco-Ematologia e Terapia Cellulare e Genica Ospedale Pediatrico Bambino Gesu - IRCCS
Rome
About this study
Official title: A Phase 1/2/3 Study to Evaluate the Safety and Efficacy of a Single Dose of Autologous CRISPR-Cas9 Modified CD34+ Human Hematopoietic Stem and Progenitor Cells (CTX001) in Subjects With Severe Sickle Cell Disease
This is a single-arm, open-label, multi-site, single-dose Phase 1/2/3 study in participants with 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.
- Being tested
- Exa-cel
- Medical subject headings
- Anemia, Sickle Cell, Hematologic Diseases, Hemoglobinopathies
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Exa-celBiological
Also called Exagamglogene autotemcel, CTX001
Administered by IV infusion following myeloablative conditioning with busulfan.
| Study group | Role | What they receive |
|---|---|---|
| Exa-cel | Experimental | Exa-cel (autologous CD34+ hHSPCs modified with CRISPR-Cas9 at the erythroid lineage-specific enhancer of the BCL11A gene). Participants received a single infusion of exa-cel through a central venous catheter on Day 1. Receives: Biological: Exa-cel |
What is being measured
The primary outcome is the main question the study is designed to answer.
Percentage of Participants Who Have Not Experienced Any Severe Vaso-occlusive Crisis (VOC) for at Least 12 Consecutive Months (VF12) After Exa-cel Infusion
A VOC is a condition of SCD characterized by vaso-occlusion presenting as recurrent pain episodes. The percentage of participants who remain VOC free after achieving VF12 were data reported in the outcome measure.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Percentage of Participants Who Achieve Neutrophil Engraftment
Neutrophil engraftment is defined as the first day of 3 consecutive measurements of absolute neutrophil count (ANC)≥500/μL on 3 different days, within 42 days after exa-cel infusion without the use of unmodified CD34+ cells after reaching the nadir, defined as ANC <500/µL.
Measured: Up to 24 months post exa-cel infusion.
Time to Neutrophil Engraftment for Participants Who Achieve Neutrophil Engraftment
Neutrophil engraftment is defined as the first day of 3 consecutive measurements of absolute neutrophil count (ANC)≥500/μL on 3 different days, without use of the unmodified CD34+ cells after reaching the nadir, defined as ANC<500/μL. Time to neutrophil engraftment was calculated by the neutrophil engraftment date subtract exa-cel infusion date +1.
Measured: Up to 24 months post exa-cel infusion.
Time to Platelet Engraftment for Participants Who Achieve Platelet Engraftment
Platelet engraftment is defined as the first day of 3 consecutive measurements of unsupported (no platelet transfusions for the last 7 days) platelet ≥50,000/μL on 3 different days after Exa-cel infusion. For participants discharged early day 7 after the last platelet transfusion will be the day of platelet engraftment, as long as 3 subsequent and consecutive unsupported measurements on 3 different days are >50,000/μL. For participants who have been discharged prior to platelet engraftment, it is recommended to collect blood every 2 to 3 days to obtain an accurate assessment of platelet engraftment. Time to platelet engraftment was defined as first of 3 consecutive measurements on 3 different days with platelet ≥50 × 109/L without a platelet transfusion for 7 consecutive days.
Measured: From Exa-cel infusion up to 2 years after exa-cel infusion
Safety and Tolerability as Assessed by Number of Participants With Treatment-Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs)
Measured: From receiving exa-cel infusion up to 2 years
Transplant-related Mortality (TRM) Within 100 Days After Exa-cel Infusion
The transplant-related mortality is defined as death related to Busulfan and/or exa-cel infusion. The number and proportion of TRM participants who have died within 100 days, or with at least 100 days post exa-cel infusion.
Measured: Within 100 days after exa-cel infusion
Transplant-related Mortality Within 12 Months Post Exa-cel Infusion
The transplant-related mortality is defined as death related to Busulfan and/or exa-cel infusion. The number and proportion of TRM within 12 months will be summarized for participants who have died within 12 months, or with at least 12 months post exa-cel infusion.
Measured: Within 12 months post exa-cel infusion
All-cause Mortality
All-cause mortality from exa-cel infusion up to 2 years
Measured: From exa-cel infusion up to 2 years
Secondary outcomes (30)
Percentage of Participants Free From Inpatient Hospitalization for Severe VOCs Sustained for at Least 12 Months (HF12)
The HF12 means Free from inpatient hospitalization for severe vaso-occlusive crises (VOCs) and sustained for at least 12 months after exa-cel infusion.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Relative Reduction From Baseline in Annualized Rate of Severe VOCs for Participants Who do Not Achieve VF12 up to 24 Months After Exa-cel Infusion
The VF12 defines absence of any severe vaso-occlusive crises (VOCs) for at least 12 consecutive months after exa-cel infusion. Only severe VOCs adjudicated by an outcome measure adjudication committee as meeting the protocol definition of severe VOCs were included in the analysis. Relative reduction from baseline was calculated as 100 % × (Baseline value - post-baseline value) / Baseline value. Annualized rate is calculated by the Total number of events/number of years.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Percentage of Participants With at Least 90% Relative Reduction From Baseline in Annualized Rate of Severe VOCs for Participants Who do Not Achieve VF12 up to 24 Months After Exa-cel Infusion
Percentage of participants with at least 90% relative reduction from baseline was reported. The percentages were calculated relative to the number of participants who did not achieve VF12.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Percentage of Participants With at Least 80% Relative Reduction From Baseline in Annualized Rate of Severe VOCs for Participants Who do Not Achieve VF12 up to 24 Months After Exa-cel Infusion
Percentage of participants with at least 80% relative reduction from baseline was reported. The percentages were calculated relative to the number of participants who did not achieve VF12.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Percentage of Participants With at Least 75% Relative Reduction From Baseline in Annualized Rate of Severe VOCs for Participants Who do Not Achieve VF12 up to 24 Months After Exa-cel Infusion
Percentage of participants with at least 75% relative reduction from baseline was reported. The percentages were calculated relative to the number of participants who did not achieve VF12.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Percentage of Participants With at Least 50% Relative Reduction From Baseline in Annualized Rate of Severe VOCs for Participants Who do Not Achieve VF12 up to 24 Months After Exa-cel Infusion
Percentage of participants with at least 50% relative reduction from baseline was reported. The percentages were calculated relative to the number of participants who did not achieve VF12.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Duration of Severe VOC Free in Participant Who Have Achieved VF12
The VF12 means the absence of any severe VOC for at least 12 consecutive months after exa-cel infusion. The evaluation of the severe VOC free duration in participants who achieved VF12 started 60 days after the last RBC transfusion for post transplant support or SCD management.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Relative Reduction From Baseline in Annualized Rate of Inpatient Hospitalizations for Severe VOCs Up to 24 Months After Exa-cel Infusion
The HF12 means Free from inpatient hospitalization for severe vaso-occlusive crises (VOCs) and sustained for at least 12 months after exa-cel infusion. Relative reduction from baseline is calculated as 100% × (Baseline value - post-baseline value) / Baseline value. Annualized rate is calculated by the Total number of events/number of years.
Only severe VOCs adjudicated by an outcome measure adjudication committee as meeting the protocol definition of severe VOCs are included in the analysis.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Relative Reduction From Baseline in Annualized Duration of Hospitalization for Severe VOCs Who Did Not Achieve HF12 Up to 24 Months After Exa-cel Infusion
The HF12 means Free from inpatient hospitalization for severe vaso-occlusive crises (VOCs) and sustained for at least 12 months after exa-cel infusion. Relative reduction from baseline is calculated as 100% × (Baseline value - post-baseline value) / Baseline value. Annualized rate is calculated by the Total number of events/number of years.
Only severe VOCs adjudicated by an outcome measure adjudication committee as meeting the protocol definition of severe VOCs are included in the analysis.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Percentage of Participants With Sustained Fetal Hemoglobin (HbF) Greater Than or Equal to (≥) 20% for at Least 3 Months
The HbF evaluation started 60 days after the last RBC transfusion for post transplant support or SCD management. The last RBC transfusion refers to that in the period of the initial RBC transfusions for post transplant support or SCD management.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Percentage of Participants With Sustained HbF ≥ 20% for at Least 6 Months
The HbF evaluation started 60 days after the last RBC transfusion for post transplant support or SCD management. The last RBC transfusion refers to that in the period of the initial RBC transfusions for post transplant support or SCD management.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Percentage of Participants With Sustained HbF ≥20% for at Least 12 Months
The HbF evaluation started 60 days after the last RBC transfusion for post transplant support or SCD management. The last RBC transfusion refers to that in the period of the initial RBC transfusions for post transplant support or SCD management.
Measured: From 60 days after last RBC transfusion up to 2 years after exa-cel infusion
Number of Annualized Red Blood Cells (RBC) Units Transfused After Exa-cel Infusion
The evaluation of the number of annualized RBC units transfused after exa-cel infusion started 12 months after exa-cel infusion.
Measured: 2 years after exa-cel infusion
Participants With Relative Reduction From Baseline in Number of Annualized Units of Red Blood Cells Transfused
Relative reduction from baseline = 100% × (Baseline value - post baseline value)/Baseline value. The evaluation of the number of annualized RBC units transfused after exa-cel infusion started 12 months after exa-cel infusion.
Measured: 2 years after exa-cel infusion
Total Fetal Hemoglobin (HbF) Concentration Over Time
Measured: 2 years after exa-cel infusion
Total Hemoglobin (Hb) Concentration Over Time
Measured: 2 years after exa-cel infusion
Change From Baseline in Reticulocyte Count Over Time
Measured: 2 years after exa-cel infusion
Change From Baseline in Indirect Bilirubin Over Time
Measured: 2 years after exa-cel infusion
Percentage of Participants With Detectable Haptoglobin Over Time
Measured: 2 years after exa-cel infusion
Percentage of Participants With Lactate Dehydrogenase (LDH) Level <300 Units Per Liter (U/L) Over Time
Measured: 2 years after exa-cel infusion
Percentage of Alleles With Intended Genetic Modification Present in Peripheral Blood Leukocytes Over Time
Measured: 2 years after exa-cel infusion
Percentage of Alleles With Intended Genetic Modification Present in CD34+ Cells of Bone Marrow Over Time
Measured: 2 years after exa-cel infusion
Change in Patient-reported Outcome (PRO) Over Time Assessed Using on a 11-point Numerical Rating Scale [NRS]) for Participants ≥12 and <18 Years of Age
The 11-point pain numerical rating scale (NRS) is used to measures pain intensity on a 1-dimensional score ranging from 0 (no pain) to 10 (worst possible pain).
Measured: 2 years after exa-cel infusion
Change in Patient-reported Outcome (PRO) Over Time Assessed Using on a 11-point Numerical Rating Scale [NRS]) for Participants ≥18 and ≤35 Years of Age
The 11 point pain numerical rating scale (NRS) is used to measures pain intensity on a 1 dimensional score ranging from 0 (no pain) to 10 (worst possible pain).
Measured: 2 years after exa-cel infusion
Change in PRO Over Time Assessed Using EuroQol Quality of Life Scale (EQ-5D-Y)Visual Analogue Scale (VAS) for Participants ≥12 and <18 Years of Age
The EQ-5D VAS is a version of the EQ-5D designed for children and adolescents S). The EQ VAS records the subject's self-rated health on a 100-point VAS scale that ranged from 0 (worst imaginable health) to 100 (best imaginable health) points.
Measured: 2 years after exa-cel infusion
Change in PRO Over Time Assessed Using EuroQol Quality of Life Scale (EQ-5D-5L) for Participants ≥18 and ≤35 Years of Age
The EQ-5D VAS is a version of the EQ-5D designed for children and adolescents S). The EQ VAS records the subject's self-rated health on a 100-point VAS scale that ranged from 0 (worst imaginable health) to 100 (best imaginable health) points.
Measured: 2 years after exa-cel infusion
Change in PRO Over Time Assessed Using Functional Assessment of Cancer Therapy-bone Marrow Transplant (FACT-BMT) Score for Participants ≥18 and ≤35 Years of Age
The Functional Assessment of Cancer Therapy-Bone Marrow Transplant scale (FACT-BMT) is a quality of life instrument that assesses the effects of bone marrow transplantation (BMT) on a patient's physical, social/family, emotional, and functional well-being while taking into consideration BMT-specific concerns. The assessment has different questions, each scored on a Likert scale from 0-4. The overall score is computed by adding scores of the questions and falls in the range 0-148, with higher scores indicating higher levels of overall well-being.
Measured: 2 years after exa-cel infusion
Change in PRO Over Time Assessed Using Adult Sickle Cell Quality of Life Measurement System (ASCQ-Me) Score on Different Domains for Participants ≥18 and ≤35 Years of Age
ASCQ-Me is a disease-specific HRQoL questionnaire for adults with sickle cell disease that assesses Emotional Impact, Pain Impact, Social Functioning Impact, Stiffness Impact, Sleep Impact, Pain Episode Frequency, and Pain Episode Severity. Domain scores are reported as T-scores standardized to a reference population where mean = 50, and SD = 10. A change of approximately 5 points (1/2 SD) is considered clinically meaningful. An increase of 5 points indicates improvement for the impact domains, whereas a decrease of 5 points indicates improvement for the Pain Episode Frequency and Pain Episode Severity domains. For impact domain items higher score indicates better HRQoL and lower disease burden. For Pain items lower score indicates a better outcome. Scores are interpreted relative to the reference population mean of 50, taking into account the direction of scoring for each domain.
Measured: 2 years after exa-cel infusion
Change in PRO Over Time Assessed Using Pediatric Quality of Life Inventory (PedsQL) for Participants Greater Than or Equal to (≥) 12 and Less Than (<) 18 Years of Age
PedsQL scores were used to assess quality of life of participants. It is a standardized, generic instrument for measuring health related quality of life (HRQoL) in children and adolescents. It includes different domains (Psychosocial health, physical functioning, emotional functioning, social functioning, and school functioning). When completing the PedsQL questionnaires, respondents were asked to provide a response on a 5-point scale ranging from 0 (never a problem) to 4 (almost always a problem). Responses were then transformed to a 0 to 100 score, with higher scores reflecting better quality of life.
Measured: 2 years after Exa-cel infusion
Change in PRO Over Time Assessed Using Pediatric Quality of Life Inventory (PedsQL) Sickle Cell Disease Module (SCD) for Participants Greater Than or Equal to (≥) 12 and Less Than (<) 18 Years of Age
The PedsQL Sickle Cell Disease Module (PedsQL SCD) is a disease-specific module of the PedsQL. The tool measures self-reported health-related quality of life in participants with SCD across 9 domains: pain and hurt, pain impact, pain management (mgmt), worry I, worry II, emotions, treatment, communication I, and communication II. When completing the PedsQL SCD Module questionnaires, respondents were asked to provide a response on a 5-point scale ranging from 0 (never a problem) to 4 (almost always a problem). Responses were then transformed to a 0 to 100 score, with higher scores reflecting better quality of life.
Measured: 2 years after exa-cel infusion
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Nov 2018
- Study start27 Nov 2018
- Primary completion7 Jul 2025
- Study completion7 Jul 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (9)Papers the sponsor has linked to this study.
- Other trials for Sickle Cell DiseaseStudies of the same condition, open and under way.
- More trials run by Vertex Pharmaceuticals IncorporatedThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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 2/3
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 63 participants (actual)
Sponsor and investigators
- Lead sponsor
- Vertex Pharmaceuticals Incorporated
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- CRISPR Therapeutics
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03745287
- Sponsor's protocol ID
- CTX001-121
- Other IDs
- 2024-516067-83-00
- Status last verified
- Aug 2026
- First submitted
- 9 Nov 2018
- Last updated
- 16 Sep 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
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 40857358Ligon JA, Cupit-Link MC, Yu C, Levine J, Foley T, Rotz S, Sharma A, Gomez-Lobo V, Shah NN. Pediatric Cancer Immunotherapy and Potential for Impact on Fertility: A Need for Evidence-Based Guidance. Transplant Cell Ther. 2024 Aug;30(8):737-749. doi: 10.1016/j.jtct.2024.06.006. Epub 2024 Jun 10.
PubMed 38866240Frangoul H, Locatelli F, Sharma A, Bhatia M, Mapara M, Molinari L, Wall D, Liem RI, Telfer P, Shah AJ, Cavazzana M, Corbacioglu S, Rondelli D, Meisel R, Dedeken L, Lobitz S, de Montalembert M, Steinberg MH, Walters MC, Eckrich MJ, Imren S, Bower L, Simard C, Zhou W, Xuan F, Morrow PK, Hobbs WE, Grupp SA; CLIMB SCD-121 Study Group. Exagamglogene Autotemcel for Severe Sickle Cell Disease. N Engl J Med. 2024 May 9;390(18):1649-1662. doi: 10.1056/NEJMoa2309676. Epub 2024 Apr 24.
PubMed 38661449Sharma A, Young A, Carroll Y, Darji H, Li Y, Mandrell BN, Nelson MN, Owens CL, Irvine M, Caples M, Jerkins LP, Unguru Y, Hankins JS, Johnson LM. Gene therapy in sickle cell disease: Attitudes and informational needs of patients and caregivers. Pediatr Blood Cancer. 2023 Jun;70(6):e30319. doi: 10.1002/pbc.30319. Epub 2023 Mar 28.
PubMed 36975201Persaud Y, Mandrell BN, Sharma A, Carroll Y, Irvine M, Olufadi Y, Kang G, Hijano DR, Rai P, Hankins JS, Johnson LM. Attitudes toward COVID-19 vaccine among pediatric patients with sickle cell disease and their caregivers. Pediatr Blood Cancer. 2023 May;70(5):e30274. doi: 10.1002/pbc.30274. Epub 2023 Mar 1.
PubMed 36860093Bhoopalan SV, Yen JS, Levine RM, Sharma A. Editing human hematopoietic stem cells: advances and challenges. Cytotherapy. 2023 Mar;25(3):261-269. doi: 10.1016/j.jcyt.2022.08.003. Epub 2022 Sep 17.
PubMed 36123234Brusson M, Miccio A. Genome editing approaches to beta-hemoglobinopathies. Prog Mol Biol Transl Sci. 2021;182:153-183. doi: 10.1016/bs.pmbts.2021.01.025. Epub 2021 Mar 1.
PubMed 34175041Frangoul H, Altshuler D, Cappellini MD, Chen YS, Domm J, Eustace BK, Foell J, de la Fuente J, Grupp S, Handgretinger R, Ho TW, Kattamis A, Kernytsky A, Lekstrom-Himes J, Li AM, Locatelli F, Mapara MY, de Montalembert M, Rondelli D, Sharma A, Sheth S, Soni S, Steinberg MH, Wall D, Yen A, Corbacioglu S. CRISPR-Cas9 Gene Editing for Sickle Cell Disease and beta-Thalassemia. N Engl J Med. 2021 Jan 21;384(3):252-260. doi: 10.1056/NEJMoa2031054. Epub 2020 Dec 5.
PubMed 33283989Modarai SR, Kanda S, Bloh K, Opdenaker LM, Kmiec EB. Precise and error-prone CRISPR-directed gene editing activity in human CD34+ cells varies widely among patient samples. Gene Ther. 2021 Feb;28(1-2):105-113. doi: 10.1038/s41434-020-00192-z. Epub 2020 Sep 1.
PubMed 32873924