Study On The Culture Technology Of Anti PD-L1 Fully Human Monoclonal Antibody

PD-1 ^[1] is an important immunosuppressive molecule.It is a member of CD28 superfamily ^[2,3].It is expressed on the surface of T cells and mediates immune tolerance.The main role of PD-1 is to limit T cell activity in inflammation,infection or cancer.There are two ligands,including PD-L1 and PD-L2.T cells serve as the guardian of the human immune system,eliminating harmful cells,bacteria and viruses.Normally,T cells can distinguish harmful cells by recognizing proteins on different cell surfaces.Many tumor cells have PD-1 ligand on their surface.By binding with PD-1 on the surface of T cells,tumor cells weaken the body's anti-tumor immune response ^[4],making T cells unable to recognize tumor cells,inhibiting T cell proliferation and inducing T cells to proliferate.Apoptosis eventually leads to the escape of cancer cells.Therefore,blocking the combination of PD-1 and PD-L1 to activate the immune function of T cells is the mainstream direction of medical research.At present,the antibodies to PD-1 include Nivolumab ^[5],Pembrolizumab ^[6],Pidilizumab?CT-011?,BMS-936559,MPDL3280 A and MEDI4736.Anti-PD-1/PD-L 1 antibodies have achieved better therapeutic effects in the treatment of melanoma ^[7],lung cancer ^[8],renal cancer ^[9],breast cancer,liver cancer,and hematological malignancies ^[10],greatly prolonging the progression-free survival and overall survival.Therapeutic monoclonal antibodies have grown rapidly in clinical treatment and have become the largest class of biotechnological drugs.At present,antibody drugs have surpassed 1/2 ^[11] of the biotechnology drug market.Monoclonal antibodies have many unique advantages in cancer treatment.Firstly,the antibodies have high specificity and targeting,and low toxicity and side effects.Secondly,the antibodies are relatively stable in vivo,and the half-life can reach 10-15 days.Antibody preparation technology has experienced serum polyclonal antibody,mouse-derived monoclonal antibody^[12],genetic engineering antibody^[13].Whole-humanized antibody refers to the human antibody genetic engineering technology,which transfers all the genes encoding human antibody to genetically engineered antibody gene-deleted animals,so that animals can express human antibody and achieve the goal of full humanization of antibody.In addition to the construction of humanized antibody,we need to find out the suitable culture environment for the growth of antibody cells,the conditions for protein purification and the corresponding preparation process.The application of cell culture technology provides a prerequisite for the large-scale production of humanized antibody.The monoclonal cell line successfully expressed human anti-PD-L1 antibody,which was constructed by genetic engineering technology.The purpose of this study was to explore the technology of anti-PD-L1 human monoclonal antibody at 2L scale in the reactor culture stage.