ERBB2 and neoplasm: In principle, they can be employed to 1) aggregate receptors on cell surface causing simultaneous inhibition of multiple signaling pathways (e.g., human epidermal growth factor receptor 2 (HER2) and HER3), 2) recruit immune cells to kill tumor cells (e.g. CD19×CD3), 3) minimize drug-resistance by binding to different epitopes on an antigen (e.g. viral protein), and 4) enhance antigen−specific targeting while avoiding off-target toxicities (1–6).