A nanomedicine based on stoichiometric coordination of camptothecin and organoplatinum (II) for synergistic antitumor therapy

Precise combination therapy, involving multiple chemotherapeutics with pharmacologically synergistic antitumor effects, is a promising approach to address the challenge of monotherapy with insufficient activity towards their targets of interest. We employed Pt←pyridine coordination-driven assembly to construct a stoichiometric coordination complex of camptothecin and organoplatinum (II) (Pt-CPT). The Pt-CPT complex exhibited a remarkable synergistic effect toward several tumor cell lines, which is equal to the optimal synergistic effect of (PEt₃)₂Pt(OTf)₂ (Pt) and CPT mixture at various ratios. An amphiphilic polymer with H₂O₂-responsiveness and glutathione (GSH)-depleting ability (PO) was used to encapsulate Pt-CPT complex to enable the nanomedicine (Pt-CPT@PO) with prolonged blood circulation and elevated tumor accumulation. The Pt-CPT@PO nanomedicine exhibited remarkable synergistic antitumor efficacy and antimetastatic effect on a mice orthotopic breast tumor model. This work demonstrated the potential of stoichiometric coordination-driven assembly of organic therapeutics with metal-based drugs in developing advanced nanomedicine with optimal synergistic antitumor activity. STATEMENT OF SIGNIFICANCE: In this study, for the first time, we employed Pt←pyridine coordination-driven assembly to construct a stoichiometric coordination complex of camptothecin and organoplatinum (II) (Pt-CPT), with an optimal synergistic effect at various ratios. Then it was encapsulated into an amphiphilic polymer with H₂O₂-responsiveness and glutathione (GSH)-depleting ability (PO) to enable the nanomedicine (Pt-CPT@PO) with prolonged blood circulation and elevated tumor accumulation. The Pt-CPT@PO nanomedicine exhibited remarkable synergistic antitumor efficacy and antimetastatic effect on a mice orthotopic breast tumor model.