Development of Effective Immunotherapy for B-Cell Non-Hodgkin’s Lymphoma with CD19-Specific Cytotoxic T Cells.

Less than 60% of patients with B-cell non-Hodgkin’s lymphoma (B-NHL) can be cured with contemporary therapy. Using artificial receptors it is possible to redirect the specificity of immune cells to tumor-associated antigens, a strategy that holds great potential as a novel cancer therapy. Since B-NHL cells invariably express CD19, we transduced human peripheral blood T lymphocytes with a recently developed receptor (anti-CD19-BB-ζ), which consists of the single-chain variable domain (scFv) of an anti-CD19 monoclonal antibody, the hinge and transmembrane domains of CD8α, and the signaling domains of CD3ζ and 4-1BB. CD3ζ delivers the primary stimulus upon receptor engagement, while 4-1BB delivers co-stimulatory signals that are crucial for T-cell cytotoxicity. It has been shown that elicitation of 4-1BB signaling enhances the immune response to tumors in vivo, even when an immune response cannot be induced by CD28 stimulation. Retroviral transduction led to anti-CD19-BB-ζ expression in T cells with high efficiency: median percent of transduced cells was 60.3% (range, 25.7%–83.4%; n = 9). T lymphocytes expressing anti-CD19-BB-ζ expanded more vigorously that T cells transduced with receptors lacking 4-1BB and exerted powerful cytotoxicity against the CD19⁺ B-NHL cell lines Raji, Daudi, RL, and HT in vitro: at a 0.5: 1 effector: target ratio, mean (± SD) cell specific lymphoma cell killing was 96.6% ± 4.6% after 5–7 days of culture (4 experiments in each cell line). Transduced T cells were also effective against freshly isolated cells from patients with diffuse large, follicular large, Burkitt, and mantle cell lymphoma cultured on bone marrow-derived mesenchymal cells: in 10 samples, cell killing was 93.6% ± 5.7% at a 0.5: 1 ratio after 5–7 days of culture. Sensitivity to anti-CD19-BB-ζ-mediated killing was observed regardless of high Bcl-2 expression. T cells expressing anti-CD19-BB-ζ were also effective in a xenograft model of NHL, in which NOD/SCID mice were inoculated subcutaneously with lymphoma cells (1 x 10⁷). Subsequent inoculation of T cells (2 x 10⁶) transduced with anti-CD19-BB-ζ receptors significantly suppressed tumor growth, whereas inoculation of T cells transduced with empty control vector had no effect (3 mice for each treatment). These results provide a rationale for clinical testing of autologous T cells modified with anti-CD19-BB-ζ receptors in patients with aggressive or relapsed B-NHLs refractory to conventional therapy.