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Virtual screening for small-molecule inhibitors of PD-1/PD-L1 protein-protein interaction using in silico fragment mapping method

Inhibition of the immunity checkpoint pathway of PD -1/PD-L1 by monoclonal antibodies is effective in the clinical treatment of certain cancers and several antiPD-1 and anti-PD-L1 antibodies have been approved for therapeutic use. Against this background, attention has now focused on the search for small molecule inhibitors of PD-1/PD-L1 protein-protein interaction (PPI). In this study, we have performed a virtual screening for such small molecule inhibitors using PD-1 as a target. First, a 3D feature query for the screening was constructed making the most of the in silico fragment mapping method, and then the 3D feature query-based virtual screening of a commercial compound database was carried out. The compounds selected from the screening were then subjected to an in vitro assay (ELISA) to test for PPI inhibitory ability against PD-1/PD-L1. As a result of the assay, one molecule was identified to be a potential seed compound for small molecule PD-1/PD-L1 inhibitors.