Bioactive Macrocyclic Inhibitors of the PD-1/PD-L1 Immune Checkpoint.
Magiera-Mularz, K., Skalniak, L., Zak, K.M., Musielak, B., Rudzinska-Szostak, E., Kocik, J., Grudnik, P., Sala, D., Zarganes-Tzitzikas, T., Shaabani, S., Domling, A., Dubin, G., Holak, T.A.(2017) Angew Chem Int Ed Engl 56: 13732-13735
- PubMed: 28881104 
- DOI: https://doi.org/10.1002/anie.201707707
- Primary Citation of Related Structures:  
5O45, 5O4Y - PubMed Abstract: 
Blockade of the immunoinhibitory PD-1/PD-L1 pathway using monoclonal antibodies has shown impressive results with durable clinical antitumor responses. Anti-PD-1 and anti-PD-L1 antibodies have now been approved for the treatment of a number of tumor types, whereas the development of small molecules targeting immune checkpoints lags far behind. We characterized two classes of macrocyclic-peptide inhibitors directed at the PD-1/PD-L1 pathway. We show that these macrocyclic compounds act by directly binding to PD-L1 and that they are capable of antagonizing PD-L1 signaling and, similarly to antibodies, can restore the function of T-cells. We also provide the crystal structures of two of these small-molecule inhibitors bound to PD-L1. The structures provide a rationale for the checkpoint inhibition by these small molecules, and a description of their small molecule/PD-L1 interfaces provides a blueprint for the design of small-molecule inhibitors of the PD-1/PD-L1 pathway.
Organizational Affiliation: 
Department of Organic Chemistry, Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060, Krakow, Poland.