Used in the synthesis of antibody-drug conjugates (ADCs), this compound serves as a linker-payload component that enables targeted delivery of cytotoxic agents to cancer cells. The Fmoc group provides a protective function during peptide assembly, while the D-Val-Cit sequence acts as a cleavable linker sensitive to cathepsin B, an enzyme overexpressed in tumor tissues. Upon internalization of the ADC into cancer cells, the linker is enzymatically cleaved, releasing the active drug. The PAB (para-aminobenzyl alcohol) spacer facilitates efficient release of the payload through a self-immolative mechanism, ensuring potent and selective cell killing. Its design supports improved stability in circulation and controlled intracellular activation, making it valuable in developing safer and more effective ADCs.