This compound is primarily used in the development of antibody-drug conjugates (ADCs), which are targeted cancer therapies. It serves as a linker that connects the cytotoxic drug to the antibody, ensuring precise delivery to cancer cells. The Val-Cit segment is specifically designed to be cleaved by cathepsin B, an enzyme overexpressed in cancer cells, enabling the release of the drug at the tumor site. The PEG4 spacer enhances solubility and reduces aggregation, improving the stability and efficacy of the conjugate. The PNP (para-nitrophenyl) group acts as a reactive handle for attaching the drug molecule. This design allows for controlled drug release, minimizing damage to healthy tissues and improving therapeutic outcomes.