Cemiplimab Biosimilar uses the same protein sequences as the therapeutic antibody cemiplimab.PD-L1 and PD-L2 (B2-DC or CD273, programmed cell death ligand 2) are the two ligands for the receptor PD-1 (CD279, programmed cell death protein 1).Cemiplimab (anti-PD-1) is an intravenous human monoclonal antibody directed against programmed cell death-1 receptor (PD-1) and blocks its interaction with programmed death ligands 1 (PD-L1) and 2 (PD-L2). Cemiplimab blocks T-cell inactivation and enhances the immune systems anti-tumor response.Binding of the programmed death receptor (PD) ligands PD-L1 and PD-L2, to the PD-1 receptor inhibits T-cell proliferation and cytokine production. The upregulation of PD-1 ligands occurs in some tumors and signaling through this pathway may contribute to the inhibition of active T-cell immune surveillance of tumors. Cemiplimab is a recombinant human immunoglobulin G4 (IgG4) monoclonal antibody that binds to the PD-1 receptor and blocks its interaction with PD-L1 and PD-L2 ligands, causing PD-1 pathway-mediated inhibition of the immune response, including the anti-tumor immune response. In mouse tumor models, blocking PD-1 activity resulted in decreased rates of tumor growth.