Application of a Standardized Flow Cytometry Panel for Defining and Monitoring the Immunophenotype of CAR-T Cells

Chimeric antigen receptor T-cells (CAR-T) have emerged as an extremely promising therapy for hematological malignancies. The immunophenotype of apheresis material and the CAR-T cell product is known to be predictive of the likelihood of response to treatment of certain malignancies. Central memory and stem cell-like memory T cell phenotypes are associated with a more sustained proliferative response and long-term CAR-T persistence (Fraietta et al, Nature Medicine, 2018).

There is an unmet need for standardized methods and reagents to reliably profile the memory phenotype of CAR-Ts to better evaluate product quality, and support improvements in CAR-T manufacturing. The BD Biosciences dried memory T-cell panel contains a pre-validated mixture of 7 antibodies for the identification of naïve, stem cell memory, central memory and effector memory CD4+ and CD8+ T cell subsets. The pre-mixed dried antibody tube offers consistency in staining profiles over time and reduces the risk of operator errors. Additional drop-in antibodies can complement the panel and enable more in-depth evaluation of the T cell phenotype. Here we demonstrate the use of this panel with drop-in markers to monitor changes in expression of PD-1, TIM-3, LAG-3, HLA-DR, CD45RO, and CXCR3 on T cells transduced to express our novel anti-CD37 CAR. Cells were stained at day 0 prior to transduction, day 7, and following resting and re-stimulation, and acquired on a 12 color BD FACS Lyric.

The use of a standardized memory T-cell panel will allow us to more accurately evaluate how T-cell phenotype impacts on the efficacy and longevity of response in patients receiving CAR-T therapies.