Antibody-Drug Conjugate (ADC)
A therapeutic combining a monoclonal antibody with a cytotoxic drug via a chemical linker. While ADCs use antibodies rather than peptides as targeting agents, the concept of targeted conjugate delivery is shared with radiopharmaceutical peptides and peptide-drug conjugates.
Technical Context
While ADCs use antibodies rather than peptides as targeting agents, the conjugation chemistry, linker design, and targeted delivery concepts are shared with peptide-drug conjugates. ADC components: monoclonal antibody (targeting) + linker (cleavable — protease, acid, or glutathione-sensitive; or non-cleavable) + cytotoxic payload (typically potent microtubule inhibitors or DNA-damaging agents). The drug-to-antibody ratio (DAR) affects efficacy and tolerability. For peptide-based targeted delivery, the smaller size of peptides (2-5 kDa vs ~150 kDa for antibodies) offers advantages in tumour penetration (faster diffusion through interstitial space) and manufacturing (chemical synthesis vs biological production). However, peptides have shorter half-lives than antibodies, requiring half-life extension strategies.