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, especially for hematologic malignancies. Currently, all of the FDA-approved CAR T therapies are autologous in nature. This presents as a limitation since generating CAR T cell using the patient’s own blood leads to higher costs and a 3–4 week production time. 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 aims to utilize the CD45RA-negative fraction containing memory T cells which has lower alloreactivity and reduced risk to cause graft-versus-host disease (GVHD).

Methods: The CD45RA-negative T cells were obtained through magnetic separation of CD45RA-labeled PBMCs. This process yielded the flow-through containing the unlabeled CD45RA-negative fraction which was then used to produce CAR T cells through lentiviral transduction. The generated CD45RA-negative anti-BCMA CAR T cells were compared to nondepleted anti-BCMA CAR T cells according to transduction efficiency, cell expansion, memory phenotype and cell subset. 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 vitro co-culture assay.

Conclusion: The data demonstrate CD45RA depletion as a feasible approach to generating allogeneic anti-BCMA CAR T cells