Feasibility of generating allogeneic BCMA-directed CAR T cells using CD45RA depletion

Abstract

Backgrounds: Chimeric antigen receptor (CAR) T cell therapy has recently exhibited promise as cancer treatment, especiallyfor hematologic malignancies. Currently, all of the FDA-approved CAR T therapies are autologous in nature. This presentsas a limitation since generating CAR T cell using the patient’s own blood leads to higher costs and a 3–4 week productiontime. To overcome this, allogeneic CAR T cell-therapy is being explored. Objective: In this study, CD45RA depletion was used to generate allogeneic anti-BCMA CAR TT cells. This approach aimsto utilize the CD45RA-negative fraction containing memory T cells which has lower alloreactivity and reduced risk to causegraft-versus-host disease (GVHD). Methods: The CD45RA-negative T cells were obtained through magnetic separation of CD45RA-labeled PBMCs. Thisprocess yielded the flow-through containing the unlabeled CD45RA-negative fraction which was then used to produceCAR T cells through lentiviral transduction. The generated CD45RA-negative anti-BCMA CAR T cells were compared tonondepleted anti-BCMA CAR T cells according to transduction efficiency, cell expansion, memory phenotype and cellsubset. Cytotoxic function was also assessed through co-culture assays. Results: Results show higher transduction efficiency and MFI of CD45RA-negative CAR T cells on days 4 and 11,respectively with no difference in expansion. They also feature more CD4+ cell subset and Tem memory phenotype. Results show no statistically significant difference between non-depleted and depleted anti-BCMA CAR T cells in in vitroco-culture assay. Conclusion: The data demonstrate CD45RA depletion as a feasible approach to generating allogeneic anti-BCMA CART cells.