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Efficient evolved antibody mimetic designed ankyrin repeat proteins against programmed death-ligand 1 on E. coli surface display

Song, Xiaoda, Chen, Xiaofei, Liu, Li, Yi, Yuting, Tian, Hong, Gao, Xiangdong, Yao, Wenbing
Biochemical engineering journal 2019 v.148 pp. 1-8
animal experimentation, antibodies, antigens, drugs, immunotherapy, magnetism, mice, neoplasm cells, neoplasms, proteins, solubility
Designed ankyrin repeat proteins (DARPins) are a kind of proteins containing the similar characteristics to antibodies. Which can specifically bind the target with high affinity. Here, we described an efficient method to select of DARPins effectively against the programmed death-ligand 1(PD-L1), a prominent target for cancer immune therapy, by E. coli surface display. E. coli surface display combined with magnetic cell sorting (MACS) were easy to manipulate with the advantages of solubility selected, antigen conformation kept and easily unbinding DARPins washed. The selected DARPin bound specifically to PD-L1 overexpressing cell CT26 and had a micromolar affinity for PD-L1. Animal experiments with tumor-bearing mice were demonstrated that the selected DARPin could significantly inhibit the growth rate of PD-L1 overexpressing tumor cells. This selected method of DARPin may provide a quick drug candidate generation method for cancer immunotherapy.