Envafolimab is a humanized nanobody (VHH-hIgG1 Fc fusion protein) directed against the human protein ligand PD-L1, with potential immune checkpoint inhibitory and antineoplastic activities. Envafolimab biosimilar uses the same protein sequences as the therapeutic antibody envafolimab.PD-L1 (B7-H1 or CD274, programmed cell death ligand 1) and PD-L2 (B2-DC or CD273, programmed cell death ligand 2) are the two ligands for the receptor PD-1 (CD279, programmed death 1). PD-L1 is an immune checkpoint molecule expressed on both tumor cells and certain immune cells. The binding of PD-L1 to its receptors PD-1 or B7.1 on activated T cells causes an inhibitory signal to suppress their production in the lymph nodes, thereby preventing immune responses to events such as pregnancy or autoimmune disease. This pathway is also utilized by cancer cells to evade the immune system through evasion of anti-tumor T-cell response. Furthermore, over-expression of PD-L1 and PD-1 has been linked to increased tumor aggressiveness and poorer prognosis. Envafolimab binds directly and selectively to PD-L1 and blocks interaction with both PD-1 and B7.1 receptors, thus reinvigorates and enhances the bodys adaptive anti-cancer activity. Disrupting the PD-L1/B7.1 interaction may also enhance T-cell priming, which could result in increased duration of response and survival.
