We developed SAPCon, a STING-activating polymer–drugconjugate platform based on strain-promoted azide–alkyne cycloadditionof a novel dimeric amidobenzimidazole (diABZI) STING prodrug to hydrophilicpoly(dimethylacrylamide-co-azido-ethylmethacrylate)polymer chains through a cathepsin B-responsive linker to increasecirculation time and enable passive tumor accumulation. Here, CTSB is linked to neoplasm.