Tumor Cell Membrane-Based Peptide Delivery System Targeting to Tumor Microenvironment for Cancer Immunotherapy and Diagnosis

\The development of effective delivery system for peptides targeting to the tumor microenvironment has always been a hot topic in the field of cancer diagnosis and therapy. A multifunctional delivery system by encapsulating superparamagnetic iron oxide nanoparticles (SPIO NPs) with tumor cell membrane obtained by hypotonic lysis followed by mechanical fragmentation was constructed to effectively deliver therapeutic peptides. SPIO nanoparticles were encapsulated with H460 lung cancer cell membranes (SPIO NP@M) and peptides consisted of PD-L1 inhibitory peptide (TPP-1) and MMP2 substrate peptide (PLGLLG) was conjugated to H460 membrane (SPIO NP@M-P). The abilities of homologous targeting, cytotoxicity, pharmacokinetics, and tumor targeting ability of SPIO NP@M-P were evaluated. TPP-1 peptide was delivered and released to the tumor microenvironment through the homotypic effect of tumor cell membrane and specific digestion by the tumor specific enzyme, MMP2. The newly developed delivery system (SPIO NP@M-P) for PD-L1 inhibitory peptide could effectively extend the half-life of the peptides (60 times longer) and meanwhile maintain the ability to re-activate T cell and inhibit the tumor growth in vitro and in vivo. Furthermore, SPIO NPs in the system could be used as a tumor imaging agent and thus indicate the effect of peptide treatment. The SPIO NP@M might provide a promising theranostic platform for therapeutic peptide application in cancer therapy.