Redox‐responsive dual‐drug nanomedicine integrating cisplatin and trypsin for synergistic reversal of tumor chemoresistance

Abstract To overcome cisplatin resistance without increasing systemic toxicity, we rationally elaborated a glutathione‐activatable prodrug nanomedicine that chemically co‐encapsulates cisplatin and a masked protease. First, a redox‐labile succinimide linker (NC‐ss‐COOH) was covalently grafted onto the ε‐amino groups of trypsin to create a “pro‐protease” (ssTrypsin) whose catalytic activity is completely silenced in circulation but instantly restored (≥96%) upon cleavage by intratumoral GSH. Simultaneously, cisplatin was stably coordinated to the carboxyl‐rich backbone of cRGD‐PEG‐polyglutamic acid and carboxyl‐rich ssTrypsin, forming a polymer–Pt(II) prodrug that prevents premature Pt‐GSH adduct formation. These two prodrugs co‐self‐assemble into potent anti‐tumor nanoconstructs that actively target α v β 3 /α v β 5 ‐overexpressing tumors. Upon GSH‐triggered activation, the dual‐drug combination exerts complementary actions: (i) released cisplatin directly damages DNA, while (ii) reactivated trypsin proteolytically degrades all intracellular, cytomembrane, and extracellular proteins as possible (including DNA‐repair proteins), collectively re‐sensitizing resistant cells. This “prodrug + pro‐enzyme” strategy yields a 2.5‐fold reduction in IC 50 against A2780DDP cells and 77% tumor suppression in vivo, all with minimal off‐target toxicity.