Anti-disialoganglioside GD2
IgG antibodies have shown clinical efficacy in solid
tumors that lack
human leukocyte antigens (e.g.,
neuroblastoma) by relying on Fc-dependent cytotoxicity. However, there are
pain side effects secondary to complement activation. T-cell retargeting
bispecific antibodies (BsAb) also have clinical potential, but it is thus far only effective against liquid
tumors. In this study, a fully humanized hu3F8-BsAb was developed, in which the anti-CD3 huOKT3
single-chain Fv fragment (ScFv) was linked to the carboxyl end of the anti-GD2
hu3F8 IgG1 light chain, and was aglycosylated at N297 of Fc to prevent complement activation and
cytokine storm. In vitro, hu3F8-BsAb activated T cells through classic immunologic synapses, inducing GD2-specific
tumor cytotoxicity at femtomolar EC50 with >10⁵-fold selectivity over normal tissues, releasing Th1
cytokines (TNFα, IFNγ, and
IL2) when GD2⁺
tumors were present. In separate murine
neuroblastoma and
melanoma xenograft models, intravenous hu3F8-BsAb activated T cells in situ and recruited intravenous T cells for
tumor ablation, significantly prolonging survival from local recurrence or from metastatic disease. Hu3F8-BsAb, but not control BsAb, drove T cells and monocytes to infiltrate
tumor stroma. These monocytes were necessary for sustained T-cell proliferation and/or survival and contributed significantly to the antitumor effect. The in vitro and in vivo antitumor properties of hu3F8-BsAb and its safety profile support its further clinical development as a
cancer therapeutic, and provide the rationale for exploring aglycosylated
IgG-scFv as a structural platform for retargeting human T cells.