In-situ cascade assembled peptide-drug conjugate for the treatment of bladder cancer by enhancing membrane-entry and lysosome destabilization

Peptide-drug conjugates (PDC) have recently garnered substantial attention as promising strategies for targeted tumor therapy. However, the clinical efficacy of PDC is limited by poor membrane permeability and inherent lysosomal sequestration. Herein, we report an in-situ cascade assembled peptide-drug conjugate (ISCA-PDC) accomplished by integrating CXCR4-targeting cyclic peptide (Cyclo(DTyr-NMe-DOrn-Arg-2Nal-Gly)), a lysosomal-triggered assembled peptide linker (VEALYL) decorated with pH-sensitive moiety (cis-aconitic anhydride, CAA), and cytotoxic payload (camptothecin, CPT), to improve the tumor membrane permeability and realize lysosomal destabilization, ultimately enhancing the chemotherapy of bladder Cancer. In the acidic microenvironment (pH 6.5) of the tumor, ISCA-PDC could first self-assemble into nanoparticles (NPs-PDC) after the hydrolysis of CAA and quickly enter the lysosome via CXCR4-mediated endocytosis to improve tumor membrane permeability. Following transformation into nanofibers (NFs-PDC) within lysosomes (pH 5.0), the permeability of the lysosomes was markedly enhanced, resulting in Cathepsin B-induced Apoptosis and CPT release. In addition, ISCA-PDC exhibited highly potent antitumor efficacy, which extended the overall survival of tumor recurrence model mice and led to the eradication and regression of T24-luc orthotopic xenograft mice. The concept of in-situ cascade-assembled PDC can be extended by conjugation with Other chemotherapeutic agents, suggesting a generalizable strategy for nanotherapeutic enhancement in solid tumors.