Anti-CD3×anti-GD2 bispecific antibody redirects T-cell cytolytic activity to neuroblastoma targets

Background: The ganglioside GD2 is an attractive target for immunotherapy of neuroectodermal tumors. We tested a unique bispecific antibody anti-CD3×anti-GD2 (3F8BiAb) for its ability to redirect activated T cells (ATC) to target GD2-positive neuroblastomas. Procedure: ATC were generated from normal human peripheral blood mononuclear cells (PBMC) by stimulating the PBMC with OKT3 and expanding the T cells in the presence of interleukin 2 (IL-2) for 14 days. ATC were armed with 3F8BiAb (100ng/10⁶cells) or Her2BiAb (50ng/10⁶cells) prior to use. 3F8 BiAb were tested for its dual-binding specificity to GD2 expressed on cancer cell lines and CD3 expressed on ATC. 3F8BiAb-armed ATC were further tested ex vivo for their cytotoxicity against GD2 positive tumor targets and its ability to induce cytokine response upon binding to targets. Results: GD2 expression in neuroblastoma cells was confirmed by FACS analysis. Specific binding of 3F8BiAb to the tumor targets as well as to ATC was confirmed by FACS analysis. 3F8BiAb-armed ATC exhibited specific killing of GD2 positive neuroblastoma cell lines significantly above unarmed ATC (P<0.001). GD2BiAb-armed ATC secreted significantly higher levels of Th₁ cytokines and chemokines compared to unarmed ATC (P<0.001). Conclusions: These preclinical findings support the potential of a novel immunotherapeutic approach to target T cells to neuroblastoma.