A Gene Transfer Study Inducing Fetal Hemoglobin in Sickle Cell Disease (GRASP, BMT CTN 2001)

This is an open-label, non-randomized, multi-center, phase 2 study involving a single infusion of autologous bone marrow derived CD34+ HSC cells transduced with the lentiviral vector containing a short-hairpin RNA targeting BCL11a. 25 patients ages 13 to 40 will be enrolled at sites across the US. The main goal of this study is to determine whether the treatment will lead to a complete absence of severe vaso-occlusive events (VOEs) in patients with severe SCD. After meeting eligibility criteria for the study, patients will receive blood transfusions for a period of at least 3 months prior to hematopoietic stem cell collection, with a goal of achieving a HbS level ≤ 30% by the time of mobilization. Patients will then undergo peripheral stem cell mobilization and have their cells collected by apheresis. The collected cells of each subject will be split into 2 portions; one portion for transduction with the lentiviral vector, and one portion set aside as a back-up product in the event a rescue treatment is needed. Patients may undergo multiple rounds of collection if sufficient numbers of cells are not obtained with the first collection. Transduction will be carried out on the selected CD34+ cells and transduced cells will be cryopreserved. Patients will undergo standard work-up for autologous bone marrow transplantation prior to proceeding with conditioning and infusion of gene-modified cells. Patients will receive myeloablative conditioning with busulfan administered on days -5 to -2, prior to infusion of transduced cells. The transduced cells will be infused intravenously over 30-45 minutes after standard pre-hydration and premedication according to institutional guidelines. Patients will be followed for 24 months post-infusion of gene modified cells.