Characterization of Clinically Evaluated Small-Molecule Inhibitors of PD-L1 for Immunotherapy
Alicja Slota, Katarzyna Gołębiowska-Mendroch, Justyna Kocik-Krol, Bogdan Musielak, Małgorzata Stec, Kazimierz Węglarczyk, Maciej Siedlar, Łukasz Skalniak, Jacek Plewka, Katarzyna Magiera‐Mularz
Abstract
High Resolution Image Download MS PowerPoint Slide Cancer immunotherapy aims to employ the immune system to target cancer cells. The PD-1/PD-L1 axis is a critical immune checkpoint that tumors exploit to evade immune surveillance. In this study, we characterized three small-molecule PD-L1 inhibitors, Evixapodlin, MAX-10181, and INCB086550, currently undergoing clinical trials for cancers such as non-small cell lung cancer, renal cell carcinoma, urothelial carcinoma, hepatocellular carcinoma, and melanoma. Using the homogeneous time resolved fluorescence assay, we confirmed that each compound potently disrupts human PD-1/PD-L1 binding with IC 50 values in the nanomolar range. PD-L1 oligomerization upon inhibitor binding was demonstrated through NMR analysis and confirmed by X-ray crystallography, which finally elucidated the binding interactions that stabilize these inhibitors at the PD-L1 interface. Cellular assays revealed dose-dependent T-cell activation, demonstrating the immunomodulatory potential of each compound and its cytotoxicity profiles. These findings underscore the promise of small-molecule PD-L1 inhibitors as viable alternatives to antibody-based therapies in cancer immunotherapy.