Fig. 3

hAB21 potentiates macrophage-mediated ADCP and delays tumor growth in SIRPα v1/v2 humanized mouse model. a In vitro phagocytosis experiment with human M-CSF derived MDMs and DLD-1 cells in the presence of titrated hAB21, HEF-LB or isotype control (Fc inactive) antibodies. Percent of macrophages that engulfed CFSE-labelled tumor cells is indicated on the y-axis. On the y-axis, closed circle indicates background phagocytosis observed with media only. b MDA-MB-321 TNBC cells were implanted subcutaneously on the right flanks of humanized mice engrafted with human CD34+ cells from SIRPA v1/v2 donor. On day eight, mice with established tumors were randomized, n = 5 mice/group, and treated intratumorally with PBS, clone HEF-LB, and AB21 mIgG1_N297A. Mice were treated four times every 3 days. ****p < 0.0001, statistics were performed using Two-Way ANOVA, Tukey’s multiple comparisons test