Monitoring CAR T cells in peripheral blood by flow cytometry following Tisagenlecleucel in Fundeni Clinical Institute, Bucharest

: Over the past few years, the introduction of chimeric antigen receptor (CAR) T-cell therapy by the FDA has shown remarkable success in treating various hematologic malignancies. However, the limited response and resistance observed in some patients have hindered its broader application. : At Fundeni Clinical Institute, we implemented the use of Tisagenlecleucel, a second-generation CAR T cell therapy, in April 2022. This therapy targets CD19, an antigen expressed in all B lineage cells. To assess the cellular kinetics of CAR T cell-treated patients and conduct further research, we developed an 8-color/10-parameter flow cytometry tube. This tube utilizes a biotinylated CD19 CAR Detection Reagent with high sensitivity and specificity for CD19-targeted CARs, enabling us to effectively separate CAR T cells from normal T cells. : Through immunophenotyping, we successfully identified circulating CAR T cells and distinguished various subtypes of immune cells in the peripheral blood of infused patients. Furthermore, we validated the accuracy of our flow cytometry panel for monitoring the progress of CAR T cell therapy. : This paper highlights the implementation of our flow cytometry monitoring panel for CAR T cells following Tisagenlecleucel therapy at Fundeni Clinical Institute. Our practical solution allows us to identify CAR T cells, assess B cell presence, and characterize different T cell subtypes in our patients. This standardized approach enhances our understanding and monitoring of CAR T cell therapy, leading to improved patient care and outcomes.