Used in antibody-drug conjugate (ADC) development, this compound serves as a linker-payload component that enables site-specific conjugation through its DBCO group, which undergoes strain-promoted azide-alkyne cycloaddition without catalysts. The PEG3 spacer improves solubility and reduces aggregation, enhancing bioavailability and stability in circulation. The EVCit-PAB moiety acts as a cleavable linker, releasing cytotoxic agents upon intracellular processing, particularly in the lysosomal environment after ADC internalization by target cells. This design is applied in targeted cancer therapies to deliver potent drugs selectively to tumor cells, minimizing off-target toxicity and improving therapeutic index.