Tumor vasculature-targeting PEGylated peptide-drug conjugate prodrug nanoparticles improve chemotherapy and prevent tumor metastasis

Metastasis is the main cause of death in cancer patients; therefore, new strategies or technologies that can inhibit the growth of primary tumors and their metastatic spread are extremely valuable. In this study, we selected an E-selectin-binding peptide as a targeting ligand and an inhibitor of metastasis, and conjugated this peptide with SN38 and PEG to produce an amphiphilic PEGylated peptide-drug conjugate (PDC). Novel self-assembled nanoparticles were then formed by the amphiphilic conjugate. The particles were actively targeted to the tumor vasculature by the peptide and passively to the tumor site by the enhanced permeability and retention (EPR) effect. As a nano-prodrug, this multifunctional conjugate (PEG-Pep-SN38) could reduce tumor growth, with an effect similar to that of irinotecan. Moreover, it could prolong the survival of mice bearing primary HCT116 tumors, which was not observed for its parent drug, SN38, nor the clinical prodrug of SN38 (irinotecan). Furthermore, this PDC prodrug prevented B16–F10 colonization in the lungs of mice. This study describes a new tumor vasculature-targeting PDC nano-prodrug with convenient preparation and high potential for cancer therapy, with the potential to be applied to other chemotherapeutic drugs.