Preclinical evidence of anti-CD19 CAR-T cell in vitro and in vivo efficacy against CD19-expressing acute myeloid leukemia.

[OBJECTIVE] Chimeric antigen receptor-modified T cell (CAR-T) therapy has demonstrated remarkable efficacy against refractory B-cell malignancies. This approach is more challenging in non-B-cell hematological malignancies such as acute myeloid leukemia (AML), especially because of target antigen selection difficulty and putative endogenous tumor cell resistance. Nonetheless, some AMLs express CD19, making them potential candidates for anti-CD19 CAR-T (CART19) therapy. This study aimed at establishing preclinical evidence supporting the therapeutic potential of academically developed CART19 cells for the treatment of CD19⁺AMLs.

[METHODS] Luciferase/Green Fluorescent ProteinAML-derived Molm-13 cells were transduced with gammaretroviral vectors to express CD19 (Molm-13-CD19), turning them into potential AML targets for CART19, generated from healthy donor T lymphocytes after lentiviral vector transduction. These CD19AML cells could be used in vitro for assessing CART19 specific cytotoxic capacity and in vivo for evaluating CART19 anti-tumor efficacy in immunodeficient mice.

[RESULTS] In vitro, flow cytometry-based cytotoxicity assays evidenced CART19 potent specific killing of Molm-13-CD19 cells, up to 75% at a 2.5:1 effector-to-target ratio after 16 h of coculture. In vivo, CART19 significantly prolonged survival of immunodeficient mice bearing Molm-13-CD19-derived tumors by efficiently killing AML cells, as assessed by bioluminescence imaging. Moreover, in immunodeficient mice lacking MHC to limit graft-versus-host disease, CART19 persisted in bone marrow and spleen up to 90 days post-treatment as evidenced by flow cytometry.

[CONCLUSION] These findings demonstrated CART19 efficacy against CD19AML and allowed us to set up a clinical trial which is ongoing (NCT06649227), based on the injection of academically-produced CART19 in strictly selected patients with relapsed/refractory CD19AML.