Anti-CD19 Monoclonal antibody, clone 2E4 [Alexa Fluor® 700]

T cells modified with CD19-specific chimeric antigen receptors (CARs) result in significant clinical benefit for leukemia patients but constitute a challenge for manufacturing. We have recently demonstrated the in vivo generation of CD19-CAR T cells using the CD8-targeted lentiviral vector (CD8-LV). In this study, we investigated the in vivo generation of CD4(+) CART cells using CD4-targeted LV (CD4-LV). Administration of CD4-LV into NSG mice transplanted with human peripheral blood mononuclear cells (PBMCs) led to 40%-60% of human CD4(+) lymphocytes being CAR positive while CD8(+) cells remained CAR negative. CAR(+) T cells displayed a T helper 1 (Th1)/Th2 phenotype, which was accompanied by CD19(+) B cell elimination. Intravenous administration of CD4-LV into NSG mice reconstituted with human CD34(+) cells induced CAR expression and B cell elimination within 2-3 weeks post-injection. Preclinical analysis in a tumor mouse model revealed that mice administered CD4-LV exhibited faster and superior tumor cell killing compared to mice injected with CD8-LV alone or as a mixture with CD4-LV. Further analysis suggests that CD4(+)CAR(+) cells may outperform CD8(+)CAR(+) cells, especially at a high burden of target antigen, mainly since CD8 cells are more prone to exhaustion. This first description of in vivo-generated CD4(+) CAR T cells supports their importance for cellular therapy.

Background: No effective treatment exist for patients with relapsed and refractory B-cell lymphoma, until the advent of anti-CD19 chimeric antigen receptor (CAR) T-cells. Therefore, this study aimed to explore the factors affecting the efficacy of anti-CD19 CAR T-cell and the adverse reactions of the therapy. Methods: We recruited 11 patients with relapsed and refractory B-cell lymphoma. The number of anti-CD19 CAR T-cells, proliferation, and adverse reactions were recorded in detail, to explore the relationship between the factors affecting the efficacy of anti-CD19 CAR T-cell and the long-term survival of patients. Results: The 11 patients in our study had a total overall response rate of 100%, after receiving anti-CD19 CAR T-cells. The median follow-up was 253 days (range, 130-1,017 days). The median overall survival (OS) and median progression-free survival (PFS) were not reached. After 3 months of treatment, the complete remission (CR) rate was 63.6% (7/11). As of December 7, 2019, 5 patients had maintained CR for a period exceeding 1 year, including 2 patients who had maintained CR for more than 1,000 days. The patients who received 3 or 4 lines of chemotherapy were more likely to have sustained remission than the patients who received <2 or > 4 lines of chemotherapy. Each of the 4 patients in the study who had diffuse large B cell lymphoma (DLBCL) progression all had high myc protein expression (positive incidence: 30-80%). The incidence of Grade 2 cytokine release syndrome (CRS) was 36.4% (4/11), and Grade 3 CAR T-cell-related encephalopathy syndrome (CRES) was experienced by 1 patient. The occurrence of adverse reactions was not significantly related to the infusion dose, peak amplification time, or maximum copy amount. The immunoglobulin levels of the four patients who died showed a significant downward trend. Interleukin1 ss (IL-1 ss), interferon-gamma (IFN-gamma), interleukin-10 (IL-10), and interleukin-17A (IL-17A) appeared to be associated with the occurrence of CRS and CRES. Conclusions: Anti-CD19 CAR T-cell treatment is a new therapy for patients with relapsed and refractory B-cell lymphoma. Among the small sample size in this study, it demonstrated high efficiency and safety.