Culturing adequate CAR-T cells from less peripheral blood to treat B-cell malignancies

Objective:Chimeric antigen receptor-modified T(CAR-T)cells have shown impressive results against relapsed/refractory B cell malignancies.However,the traditional manufacture of CAR-T cells requires leukapheresis to isolate large amounts of peripheral blood T cells,thus making some patients ineligible for the procedure.Methods:We developed a simple method for CAR-T cell preparation requiring small volumes of peripheral blood.First,CD3+T cells isolated from 50 mL peripheral blood from patients(B-cell malignancies)were stimulated with immobilized anti-CD3/RetroNectin in 6-well plates and then transduced with CAR-expressing lentiviral vector.After 4 d,the T cells were transferred to culture bags for large-scale CAR-T cell expansion.In vitro and animal experiments were performed to evaluate the activity of the manufactured CAR-T cells.Finally,29 patients with B-cell acute lymphoblastic leukemia(B-ALL)and 9 patients with B-cell lymphoma were treated with the CAR-T cells.Results:The CAR-T cells were expanded to 1–3×10^(8) cells in 8–10 d and successfully killed B cell-derived malignant tumor cells in vitro and in vivo.For patients with B-ALL,the complete remission rate was 93%1 month after CAR-T cell infusion;after 12 months,the overall survival(OS)and leukemia-free survival rates were 69%and 31%,respectively.For patients with lymphoma,the objective response rate(including complete and partial remission)was 78%2 months after CAR-T cell infusion,and after 12 months,the OS and progression-free survival rates were 71%and 43%,respectively.Cytokine-release syndrome(CRS)occurred in 65.51%and 55.56%of patients with B-ALL and B-cell lymphoma,respectively;severe CRS developed in 20.69%of patients with B-ALL and in no patients with lymphoma.Conclusions:Our novel method can generate sufficient numbers of CAR-T cells for clinical use from 50–100 mL peripheral blood,thus providing an alternative means of CAR-T cell generation for patients ineligible for leukapheresis.