Used in the synthesis of antibody-drug conjugates (ADCs) as a linker-payload component. The Fmoc-Val-D-Cit-PAB structure incorporates a self-immolative spacer (PAB) that enables controlled release of cytotoxic agents upon specific biological triggers, such as enzymatic cleavage. The D-Cit (diaminopropionic acid derivative) enhances stability and solubility during conjugation processes, while the Fmoc group allows for solid-phase peptide synthesis compatibility. This compound is particularly valuable in developing targeted cancer therapies where precise drug activation is critical.