EGFR and breast cancer: To determine the in vitro biological activity of BP-αCD3-αEGFR-ARC Exos that are anticipated to engage T cells to EGFR+ tumor cells for killing (Fig. 6A), three types of breast cancer cells including MDA-MB-453 (EGFR−), BT20 (EGFR+), and MDA-MB-231 (EGFR+), were incubated with non-activated human peripheral blood mononuclear cells (PBMCs) in the presence of purified exosomes at varied concentrations.