T‐2513 is bound to the polymer via the triglycine linker, which can be specifically cleaved by cathepsin B and subsequently release the active drug.232 Cathepsin B is a lysosomal cysteine protease that is upregulated in a wide variety of human tumors; hence, the presence of the triglycine linker is important for enhancing tumor selectivity and reducing toxicity. This evidence concerns the gene CTSB and neoplasm.