Small-Molecule Inhibitors of the Programmed Cell Death-1/Programmed Death-Ligand 1 (PD-1/PD-L1) Interaction via Transiently Induced Protein States and Dimerization of PD-L1.
Guzik, K., Zak, K.M., Grudnik, P., Magiera, K., Musielak, B., Torner, R., Skalniak, L., Domling, A., Dubin, G., Holak, T.A.(2017) J Med Chem 60: 5857-5867
- PubMed: 28613862 
- DOI: https://doi.org/10.1021/acs.jmedchem.7b00293
- Primary Citation of Related Structures:  
5N2D, 5N2F - PubMed Abstract: 
Blockade of the PD-1/PD-L1 immune checkpoint pathway with monoclonal antibodies has provided significant advances in cancer treatment. The antibody-based immunotherapies carry a number of disadvantages such as the high cost of the antibodies, their limited half-life, and immunogenicity. Development of small-molecule PD-1/PD-L1 inhibitors that could overcome these drawbacks is slow because of the incomplete structural information for this pathway. The first chemical PD-1/PD-L1 inhibitors have been recently disclosed by Bristol-Myers Squibb. Here we present NMR and X-ray characterization for the two classes of these inhibitors. The X-ray structures of the PD-L1/inhibitor complexes reveal one inhibitor molecule located at the center of the PD-L1 homodimer, filling a deep hydrophobic channel-like pocket between two PD-L1 molecules. Derivatives of (2-methyl-3-biphenylyl)methanol exhibit the structures capped on one side of the channel, whereas the compounds based on [3-(2,3-dihydro-1,4-benzodioxin-6-yl)-2-methylphenyl]methanol induce an enlarged interaction interface that results in the open "face-back" tunnel through the PD-L1 dimer.
Organizational Affiliation: 
Department of Organic Chemistry, Faculty of Chemistry, Jagiellonian University , Ingardena 3, 30-060 Krakow, Poland.