Progress in the study of PD-L1 inhibitory peptides in Suzhou Institute of Nanotechnology

In recent years, immunotherapy has become the fourth tumor treatment method after surgery, radiotherapy and chemotherapy, especially the treatment of immunocheckpoint molecules in the clinical treatment of tumor has achieved very positive therapeutic effect Programmed cell death living 1 (pcdl) and its ligand protein PD-L1 (pcdl) are important immunocheckpoint proteins with inhibitory effects At present, there are five monoclonal antibody drugs targeting these two proteins Peptides and protein molecules have similar biological activities, which can be used as alternative molecules of monoclonal antibodies, to solve the high cost and immunogenicity of antibodies and other factors that are not conducive to its wide application Zhu Yimin, researcher of Suzhou Institute of nanotechnology and nano bionics, Chinese Academy of Sciences, led the research team to screen and obtain the inhibitory polypeptide for PD-L1 molecule for the first time by using the bacterial surface display technology, verifying that it has the function of blocking PD-1 / PD-L1 signal pathway, reducing the growth of tumor cells, and providing a new tool for tumor immunotherapy Specifically, by using bacterial surface display technology, through the screening of arbitrary peptide library and biased peptide library, several peptide sequences that can specifically bind to PD-L1 were obtained; by comparing their physical and chemical properties, it was determined that one of the peptide tpp-1 (yasyhcwcwrdpgrs) has high specificity and appropriate affinity; Through in vivo and in vitro experiments, it has been confirmed that it can activate T cells to kill tumor, and can inhibit the growth of tumor in mice as well as PD-L1 antibody which has been listed on the market (see Figure) The experimental results provide a new and potential drug candidate for tumor immunotherapy Relevant research results were published in cancer immunology research, and the research work was supported by National Natural Science Foundation and Jiangsu social development project fund Paper link 　　   Tpp-1 inhibited tumor growth in mouse tumor model A Bioluminescence imaging of H460 tumor bearing mice expressing luciferase reporter gene; B, bioluminescence data statistics of tumor bearing mice with time; C, tumor volume statistics of tumor bearing mice with time; D, immunohistochemical staining results; E, quantitative analysis of immunohistochemical results.