TACSTD2 and cancer: This well-designed connector improves the binding ratio of Trop-2 antibody to SN-38, with higher toxic concentration in tumor but lower concentration in non-target with shorter half-life.219 Through optimization of the stability of linker, it can not only release SN-38 in the target tumor cells, but also achieve the bystander effects to kill neighboring cancer cells that are difficult to target.220