An Adaptive Design Basket Trial of Hematopoietic Stem Cell BCL11A Enhancer Gene Editing for Severe β-Hemoglobinopathies
A promising approach for the treatment of genetic diseases is called gene therapy. Gene therapy is a relatively new field of medicine that uses genetic material (mostly DNA) from the patient to treat his or her own disease. In gene therapy, the investigators introduce new genetic material in order to fix or replace a diseased gene, with the goal of curing the disease. The procedure is similar to a bone marrow transplant, in that the patient's malfunctioning blood stem cells are reduced or eliminated using chemotherapy, but it is different because instead of using a different person's (donor) blood stem cells for the transplant, the patient's own blood stem cells are given back after the new genetic material has been introduced into those cells. This approach has the advantage of eliminating any risk of Graft-Versus-Host Disease (GVHD), reducing the risk of graft rejection, and may also allow less chemotherapy to be utilized for the conditioning portion of the transplant procedure. The method used to fix or replace a diseased gene is called gene editing. A person's own cells are edited using a specialized biological medicine that has been formulated for use in human beings. Fetal hemoglobin (HbF) is a healthy, non-sickling kind of hemoglobin. Investigators have recently discovered a gene called BCL11A that is very important in the control of fetal hemoglobin expression. Increasing the expression of this gene in sickle cell patients could increase the amount of fetal hemoglobin while simultaneously reducing the amount of sickle hemoglobin in their blood, and therefore potentially cure the condition.
• Diagnosis of either a) sickle cell disease with genotype HbSS, HbS/B0 thalassemia, HbSD, or HbSO, or b) transfusion-dependent β-thalassemia
• Age 13-40 years.
• Clinically severe disease, defined as: For sickle cell disease, the presence of one or more of the following clinical complications: i) Minimum of two episodes of acute chest syndrome (ACS) in the 2 years before study entry. ii) History of three or more episodes of severe pain events requiring a visit to a medical facility and treatment with parenteral opioids in the 2 years before study entry. For β-thalassemia patients: i) At least 100 mL/kg/year or 10 units/year of blood transfusions, on an annualized basis for the two years preceding enrollment.
• Adequate hematologic parameters including:
∙ White blood cell (WBC) count within the range of 2.5 - 25.0 x 109 /L
‣ Platelet count within the range of 150 - 700 x 109 /L
• Adequate organ function and performance status:
∙ Karnofsky performance status ≥70%
‣ Serum creatinine \</=1.5 times the upper limit of normal for age, and calculated creatinine clearance or GFR \</= 60 mL/min/1.73 m2.
‣ Direct bilirubin ≤ 2.0 mg/dL
‣ DLCO (corrected for hemoglobin), FEV1, FVC \>50% of predicted
‣ Left ventricular ejection fraction \>40% or shortening fraction \>25%
• For sickle cell patients: Failure of hydroxyurea therapy due to lack of clinical improvement, inability to tolerate due to side effects (e.g., myelosuppression, gastrointestinal symptoms, or hepatic enzyme elevations) or not clinically indicated (such as in a patient on a chronic transfusion regimen). Clinical criteria (per above) must be met despite taking hydroxyurea for greater than or equal to 6 months, unless not indicated or not tolerated. Patients taking hydroxyurea who still meet all inclusion criteria are eligible for the trial. Hydroxyurea should be discontinued when transfusions prior to gene therapy begin.
• Confirmed sickle cell disease or β-thalassemia diagnosis by molecular genetic testing.
• No HLA genotypically-identical related appropriate bone marrow donor available.
• Parental/guardian/patient signed informed consent.
⁃ Willingness to return for follow-up for 15 years.