Antibody–Drug Conjugates (ADCs): A Review of Structural Design, Technological Evolution, and Future Perspectives

Antibody–drug conjugates (ADCs) have become an important class of targeted anticancer therapeutics by integrating the tumor selectivity of monoclonal antibodies with the potent cytotoxicity of small-molecule payloads through rational linker design. This review summarizes the structural fundamentals of ADCs, including antibodies, linkers, and payloads, and describes their coordinated mechanism of action. We trace the evolutionary trajectory of ADCs across three generations, highlighting key breakthroughs, limitations, and representative agents for each era. Furthermore, we elaborate on cleavage mechanisms of linkers (cleavable and non-cleavable). We also categorize and discuss cytotoxic payloads, covering traditional microtubule-disrupting agents, DNA-damaging agents, and novel mechanism-based payloads, along with their modification strategies and preclinical/clinical performance. Finally, we discuss representative and clinically influential ADC designs, with emphasis on the relationships among antibody, linker, and payload.