XmAb808

XmAb808 dose-dependently induces IL2/IFNγ and CD25/Bcl-xL expression in T cells co-cultured with 22Rv1-αCD3, but not in parental 22Rv1 or B7-H3-negative LOX-IMVI-αCD3^[1].
XmAb808 induces dose-dependent IL2 release from PBMCs co-cultured with HEK293-αCD3 cells only when B7-H3 is expressed^[1].
XmAb808 (6 days) stimulates T cell killing of 22Rv1-αCD3 cells, and neutralizing IL2 but not IFNγ attenuates this killing effect^[1].
XmAb808 dose-dependently increases CD4⁺ and CD8⁺ T cell counts after 5 days of coculture with 22Rv1/EpCAM×CD3, and neutralization of IL2 abolishes this expansion^[1].
XmAb808 (1 μg/mL; 24 hours) enhances EpCAM×CD3-induced IL-2/IFN-γ secretion and CD25/Bcl-xL expression in T cells co-cultured with 22Rv1 cells; it enhances EpCAM×CD3-mediated killing of 22Rv1-NLR cells, and this killing effect is inhibited by IL-2 neutralization^[1].

XmAb808 dose-dependently enhances IL-2 and IFN-γ secretion by chronically stimulated exhausted T cells co-cultured with A431 and B7-H3×CD3^[1].

XmAb808 (24 h) stimulates HLA-matched CMV-reactive T cells co-cultured with A431-NLV cells to secrete IL-2 (EC₅₀ = 186 ng/mL) and IFN-γ (EC₅₀ = 321 ng/mL); it enhances the release of IL-2 (EC₅₀ = 486 ng/mL) and IFN-γ (EC₅₀ = 883 ng/mL) from CMV-reactive T cells co-cultured with MDA-MB-231-pp65 cells, but elicits only a weak response in the parental MDA-MB-231 cell system^[1].

XmAb808 binds to B7-H3+ A431, 22Rv1, and HEK293 cells with EC₅₀ values of 184, 144, and 202 ng/mL, respectively, but does not bind to B7-H3-negative LOX-IMVI cells, and its binding potency to T cells is >100-fold lower^[1].

XmAb808 binds to human CD28 with a K_D of 213 nM and cross-reacts with mouse CD28 in BLI; it also partially competes with TGN1412 for binding to CD28, consistent with their CD28 epitopes not being completely identical^[1].
XmAb808 (10 μg; 24 h) does not activate human PBMCs to secrete IL2 or IFNγ when immobilized in the absence of Signal 1^[1].