Distribution Measurements of Chimeric Antigen Receptor-Modified T Cells Against CD19

Abstract Backgroud: The unprecedented efficacy of chimeric antigen receptor (CAR) T-cell immunotherapy of CD19+ B-cell malignancies has opened a new and useful way for the treatment of malignant tumor. Nonetheless, there are still formidable challenges in the field of CAR-T cell therapy, such as the biodistribution of CAR-T cells in vivo.Methods: We demonstrated the distribution of CAR-T cells in the absence of target cells or with target cells in the mice and the dynamic changes in the patient blood over time after infusion were deteced by qPCR and FACS. Results: CAR-T cells still proliferated in the mice without target cells and peaked at 2 weeks. However, CAR-T cells did not increase significantly in the presence of target cells within 2 weeks after infusion, but expanded at 6 weeks. In the clinical trial, we found that CAR-T cells peaked at 7-21days after infusion and can last for as long as 510 days in the peripheral blood of patients. Simultaneously, mild side-effects were noted which can be effectively controlled within two months in these patients.Conclusions: CAR-T cells can expand themselves with or without target cells in mice. CAR-T cells can persistence for a long time in patients.