Antibody-Drug conjugates (ADCs) have become a promising targeted therapy strategy that combines the specificity, favorable pharmacokinetics and biodistributions of antibodies with the destructive potential of highly potent drugs^[1].
ADCs consist of a desirable monoclonal antibody, an active cytotoxic drug and an appropriate linker. The monoclonal antibodies lead the drug precursors to the target cancer cells, in which the prodrugs can be chemically or enzymatically converted to drugs in their active forms . Conjugating cytotoxins to monoclonal antibodies that specifically tie to tumor cell surface antigens enables the drugs to be target-delivered to cancer cells and leaves normal cells unaffected. More important, many of the cytotoxic drugs that are too toxic for use in traditional chemotherapy can also be used in the construction of antibody-drug conjugates. The linkers are essential parts of antibody-drug conjugates, which account for stability in circulation,good pharmacokinetics and efficient release of toxic drugs in the tumor cells^[2,3,4].