CD19 Chimeric Antigen Receptor T Cells From Patients With Chronic Lymphocytic Leukemia Display an Elevated IFN-γ Production Profile.

CD19 chimeric antigen receptor (CAR) T cell immunotherapy has demonstrated dramatic results for the treatment of B cell malignancies such as chronic lymphocytic leukemia (CLL). As T cell defects are common in patients with CLL, we compared the T cells from these patients with healthy donors (HDs), and subsequently the CD19 CAR T cells produced from patients and HDs. Despite initial differences when comparing the phenotype of circulating T cells in patients with CLL and HDs, the CD19 CAR T cells manufactured from patients' or HDs' cells showed a similar phenotype (effector memory or terminally differentiated), both were specifically activated by and killed CD19(+) target cells, and secreted cytokines (ie, IL-2, TNF, and IFN-). The frequency of CD19 CAR T cells producing IFN- was significantly higher in cells produced from patients as compared with those produced from HDs. Furthermore, our data showed that the polyfunctional profile of CD19 CAR(+) T cells was differently modulated by CD19(+) K562 cells and autologous B cells. The increased IFN- production by CD19 CAR T cells produced from patients with CLL after in vitro stimulation, may if this is also the case in vivo, contribute to a higher risk of a cytokine release syndrome in patients. The different impact by CD19(+) target cells on the polyfunctional profile of CD19 CAR T cells in vitro underlines the importance of the choice of CD19(+) target cells when assessing CD19 CAR T cells functions.