CL2A-SN-38 is a agent-linker conjugate composed of a potent a DNA Topoisomerase I inhibitor SN-38 and a linker CL2A to make antibody agent conjugate (ADC). CL2A-SN-38 provides significant and specific antitumor effects against a range of human solid tumor types. CL2A-SN-38 uses hydrolyzable linker to deliver active agents within tumor cells and in the tumor microenvironment, resulting in bystander effects.