Aged donor derived CAR-T exhibits enhanced effector functions but shorter persistence and less memory-like phenotypes

Abstract

Background: CD19 chimeric antigen receptor (CAR) T cell therapies have been successful in B cell malignancies. Recent reports about CD19 CAR T cell therapy in B-cell acute lymphoblastic leukemia suggest that the median event-free survival of children and young adult patients is longer than that of adult patients. Since the reason is unclear, we compared the functions of CAR-T derived from young or aged mice and also healthy human donors. Methods: Young and aged B6 mice spleens (6-12 vs. ≥72 weeks) or young and aged human PBMCs (20-26 vs. 53-60 years) were used for mouse or human CAR-T preparation. 4 types of mouse CD19 CAR and 2 types of human CD19 CAR were evaluated in T cells. Results: Aged mouse CAR-T predominates with CD8+ and effector-like phenotypes at the expense of CD4+ and memory-like phenotypes. Compared to young mouse CAR-T, aged mouse CAR-T exhibited superior cytotoxicity for mouse CD19+ artificial antigen presenting cell (aAPC). Using our immune competent in vivo murine model, aged mouse CAR-T was short-lived and expanded poorly despite superior in vitro cytotoxicity. RNA-Seq suggestes that young mouse CAR-T is advantageous for cell proliferation and regulation of cell differentiation whereas aged mouse CAR-T up-regulates gene expression pathways that regulate responses to stimulus and exocytosis. Furthermore, compared to mouse CAR-T, human CAR-T is complementary with immune phenotypes after human CD19+ aAPC stimulation. Conclusions: Aged donor derived CAR-T exhibited enhanced effector functions but shorter persistence and less memory-like phenotypes. Our results suggest that the difference of clinical outcomes may be due to an age-dependent CAR-T cell phenotype that is reflected by its unique gene expression pattern, secretory profile, and/or transcription factor balance. In our future directions we are identifying potential methods to improve the function of aged donor derived CAR-T.