PD-1/L1 proteins, also known as programmed cell death 1 receptor (PD-1) and programmed cell death ligand 1 (PD-L1), are immune checkpoint proteins that play a crucial role in regulating the immune response. PD-1 is a cell surface receptor expressed on activated T cells, B cells, natural killer T cells, monocytes, and dendritic cells. Meanwhile, PD-L1 is primarily expressed on tumor cells and antigen-presenting cells. The interaction between PD-1 and PD-L1 helps to maintain self-tolerance and prevent excessive immune responses.
PD-1 and PD-L1 have gained significant attention in cancer immunotherapy. In certain tumors, cancer cells hijack the PD-1/PD-L1 pathway to evade immune surveillance and suppress the immune response against the tumor. Blocking the PD-1/PD-L1 interaction with monoclonal antibodies has shown remarkable efficacy in restoring the activity of T cells and enhancing the anti-tumor immune response. Several PD-L1 inhibitors, such as pembrolizumab, atezolizumab, and nivolumab, have been approved for the treatment of various cancers.
To facilitate research and drug discovery in this field, PD-1/L1 Libraries have been developed. These libraries are collections of compounds specifically designed to target the PD-1/PD-L1 pathway. They contain small molecules or modified peptides that can inhibit the PD-1/PD-L1 interaction or modulate the immune response mediated by these proteins.
Although monoclonal antibodies are the primary approach for PD-1/PD-L1 blockade, small molecule inhibitors offer several advantages, such as potentially improved tissue penetration and oral bioavailability. While the progress in developing small molecule inhibitors has been relatively slower compared to antibodies, recent studies have provided insights into the protein-protein interactions between PD-1, PD-L1, and their respective inhibitors[8]. These interactions can guide the discovery and development of small molecule immunotherapeutics targeting the PD-1/PD-L1 pathway.
It’s important to note that the specific compounds present in PD-1/L1 Libraries may vary depending on the source or provider. However, the libraries typically consist of diverse chemical entities with the potential to modulate the checkpoint activity and immune response mediated by PD-1/L1 receptor-ligand interaction.
In conclusion, PD-1/L1 proteins are immune checkpoint proteins involved in regulating the immune response, particularly in cancer. PD-1 is expressed on activated immune cells, while PD-L1 is primarily expressed on tumor cells and antigen-presenting cells. PD-1 blockade with monoclonal antibodies has shown promising results in cancer treatment. PD-1/L1 Libraries, on the other hand, are collections of compounds designed to target the PD-1/PD-L1 pathway and facilitate the discovery of small molecule immunotherapeutics.
