Chimeric antigen receptor (CAR) T cell therapy has shown remarkable efficacy in hematologic malignancies but faces significant challenges in solid tumors like glioblastoma. The efficacy of CAR T cells is heavily influenced by the characteristics of the starting cellular product, with less differentiated memory T cells, such as central memory (TCM) and stem-like memory (TSCM) T cells, being more conducive to generating persistent and effective CAR T cells in vivo. We aim to establish a CAR T cell manufacturing protocol with higher amount of CAR T cells with TCM/TSCM status. This study investigated the transduction efficiency and phenotypic differences between peripheral blood mononuclear cells (PBMCs) and CD62L-enriched cells as starting materials. CAR-T cells were engineered using a GALV pseudotyped retroviral vector expressing CAR molecule targeting IL13Rα2, a glioblastoma-selective tumor antigen.

PBMCs were isolated from healthy donors, and CD62L-positive cells were further enriched using magnetic bead separation. Both cell populations were transduced under identical conditions, and the transduction efficiency was assessed by determine the CAR transgene expression using flow cytometry. Additionally, a phenotypic analysis was performed on the transduced cells, focusing on markers associated with T cell differentiation and memory status.

The results revealed no significant difference in transduction efficiency between PBMCs and CD62L-enriched cells, although there was a trend for increased transduction in CD62L cells. No differences in the proportion of CD4+, CD8+, or TSCM and TCM were seen. However, PBMCs exhibited a significantly larger population of CD62Ldim cells within the TCM population, indicating a tendency of differentiation into effector cells. This difference was more pronounced in CD8+ T cells compared to CD4+ T cells.

This study highlights the potential benefits of using CD62L-enriched cells in manufacturing CAR T cells, as they display a lower tendency of differentiation into effector cells compared to PBMCs. This could potentially lead to higher persistence of the CAR T cells and increased clinical efficacy in both hematological and solid tumors. However, further investigations on the functional impact of the CD62L dim population on CAR T cell performance are necessary to fully understand the implications of these findings.