A promising approach for the treatment of genetic diseases is called gene therapy. Gene therapy is a relatively new field of medicine in which genetic material (mostly DNA) in the patient is changed to treat his or her own disease. In gene therapy, we introduce new genetic material in order to fix or replace the patient's disease 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. To introduce new genetic material into the patient's own blood stem cells we use a modified version of a virus (called a 'vector') that efficiently inserts the "correcting" genetic material into the cells. The vector is a specialized biological medicine that has been formulated for use in human beings. Fetal hemoglobin (HbF) is a healthy, non-sickling kind of hemoglobin. The investigators have discovered a gene that is very important in controlling the amount of HbF. Decreasing 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, specifically the amount in red blood cells where sickle hemoglobin causes damage to the cell, and therefore potentially cure or significantly improve the condition. The gene we are targeting for change in this study that controls the level of fetal hemoglobin is called BCL11A. 36 patients have received the gene therapy product, and the data so far has shown that the treatment has not caused any unexpected safety problems, and that it increases HbF within the red cells.
This is an expanded access protocol (EAP) involving a single infusion of autologous bone marrow derived CD34+ HSC cells transduced with the lentiviral vector containing a short-hairpin RNA targeting BCL11A. The primary purpose of this EAP is to provide access to the treatment for eligible patients with SCD who have an unmet clinical need, as determined by the treating physician, and who are unable to enroll in an appropriate clinical trial or are ineligible to receive an FDA-approved gene therapy product. After meeting the initial eligibility criteria, participants will undergo mobilization and collection of CD34⁺ hematopoietic stem and progenitor cells (HSPCs). Participants will receive red blood cell transfusions for at least two months prior to stem cell collection, with a goal of reducing the HbS level to ≤ 30% before mobilization. The collected cells will be divided into two fractions: one for drug product manufacturing, and the other stored as a back-up product for potential rescue use. Gene modification procedures will be performed on the selected CD34⁺ cell population, and the resulting drug product will be cryopreserved until infusion. Participants will receive myeloablative conditioning with busulfan on days -5 through -2, followed by a single infusion of the transduced autologous cells on Day 0. After discharge from the transplant admission, participants will continue follow-up visits for two years at their treating physician's center according to usual clinical care. Safety data and selected clinical outcome data arising during the course of routine clinical care may be collected descriptively. This EAP will end when this treatment is approved by the FDA and is commercially available for patients with SCD, or the IND Sponsor terminates the program.
Study Type
EXPANDED_ACCESS
A single infusion of autologous CD34+ HSC cells transduced with the lentiviral vector containing a shRNA targeting BCL11a
Boston Children's Hospital
Boston, Massachusetts, United States
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