PD-1, programmed death 1 receptor，is the most important immune check point molecule, belonging to CD28 superfamily. It is a 40kD, type I transmembrane protein. Binding of PD1 to its ligand PD-L1 can induce T Cell anergy and reduce T cell proliferation. One of tumor escape routes is through expression of surface PD-L1 which can induce T cell anergy and block T cell attack. Blocking PD-1 and PD-L1 axis can reset T cell function and induce tumor cell lysis by T cells.
Five monoclonal antibodies against PD-1/PD-L1 axis have been approved. Our in house project Y111 is to target PD-L1 positive tumor cells using Y-BODY platform with PD-L1 as TAA, and CD3 as IAA This project selects PD-L1 as the target antigen of tumor cells, select CD3 as the target antigen of immune cells, using YBODY® patented technology, construction of humanized anti PD-L1 and anti CD3 bispecific antibody, for the treatment of PD-L1 positive tumors.