Figure 1.

A Schematic View of ADCs and its Individual Components. The mAb targets a tumor-associated antigen, in the present case an antigen that is preferentially expressed on CSCs. The linker may be cleavable (e.g., acid-sensitive or dipeptide) or non-cleavable (e.g., maleimidocaproyl). The cytotoxin may be an antimitotic drug, active only on proliferating cells or a DNA-binding drug, active also on quiescent cells. Moreover, the cytotoxin may be hydrophilic and act only within the internalizing cell or it may be hydrophobic and act also on nearby cells, whether antigen-positive or –negative (so-called bystander effect). ADC, antibody-drug conjugate; CSC, cancer stem-like cell; mAb, monoclonal antibody.