ADC linker, a crucial component of antibody-drug conjugates (ADCs) responsible for linking the antibody to the cytotoxin, is divided into two major categories: non-cleavable and cleavable linkers. The structural design ensures specific release of the drug inside target cells while maintaining stability in circulation. Linkers chemically connect the cytotoxin to specific sites on the antibody, not directly targeting cells or tissues but influencing the intracellular transport and drug release mechanisms of ADCs. When designing ADCs, the selection of linkers is critical for regulating the timing and location of drug release to optimize efficacy and minimize side effects. Genetic-specific expression and mutations are not directly related to the linker itself, but their design needs to consider the specificity and variability of target expression.