MC-GGFG-AM-(10Me-11F-Camptothecin) acts as a linker-payload conjugate in the synthesis of ZW251, an antibody-drug conjugate (ADC) designed to target human GPC3. This ADC comprises a humanized IgG1 antibody attached to ZD06519, a novel camptothecin-based topoisomerase 1 inhibitor, through a maleimide-anchor and a cleavable glycyl glycyl phenylalanyl glycine (GGFG)-aminomethyl (AM) linker. ZW251 exhibits strong affinity for GPC3 in both human and cynomolgus monkey cells. It is characterized by rapid internalization in GPC3-positive Hepatocellular Carcinoma (HCC) cell lines and has the ability to induce bystander-mediated killing of GPC3-negative cancer cells [1].