– MC-?Ala-?Ala-?Asn(Trt)?-?PAB, is a hetero bifunctional cross-linker, useful in antibody drug conjugation (ADC). MC-?Ala-?Ala-?Asn(Trt)?-?PAB is a fissionable linker which is specifically activated in a tumor microenvironment. XQN70430 was reported in patent WO 2016026458.