Identification of CBPA as a New Inhibitor of PD-1/PD-L1 Interaction

Fengling Wang, Wenling Ye, Yongxing He, Haiyang Zhong, Yongchang Zhu, Jianting Han, Xiaoqing Gong, Yanan Tian, Yuwei Wang, Shuang Wang, Shaoping Ji, Huanxiang Liu, Xiaojun Yao

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3 Citations (Scopus)


Targeting of the PD-1/PD-L1 immunologic checkpoint is believed to have provided a real breakthrough in the field of cancer therapy in recent years. Due to the intrinsic limitations of antibodies, the discovery of small-molecule inhibitors blocking PD-1/PD-L1 interaction has gradually opened valuable new avenues in the past decades. In an effort to discover new PD-L1 small molecular inhibitors, we carried out a structure-based virtual screening strategy to rapidly identify the candidate compounds. Ultimately, CBPA was identified as a PD-L1 inhibitor with a KD value at the micromolar level. It exhibited effective PD-1/PD-L1 blocking activity and T-cell-reinvigoration potency in cell-based assays. CBPA could dose-dependently elevate secretion levels of IFN-γ and TNF-α in primary CD4+ T cells in vitro. Notably, CBPA exhibited significant in vivo antitumor efficacy in two different mouse tumor models (a MC38 colon adenocarcinoma model and a melanoma B16F10 tumor model) without the induction of observable liver or renal toxicity. Moreover, analyses of the CBPA-treated mice further showed remarkably increased levels of tumor-infiltrating CD4+ and CD8+ T cells and cytokine secretion in the tumor microenvironment. A molecular docking study suggested that CBPA embedded relatively well into the hydrophobic cleft formed by dimeric PD-L1, occluding the PD-1 interaction surface of PD-L1. This study suggests that CBPA could work as a hit compound for the further design of potent inhibitors targeting the PD-1/PD-L1 pathway in cancer immunotherapy.

Original languageEnglish
Article number3971
JournalInternational Journal of Molecular Sciences
Issue number4
Publication statusPublished - Feb 2023


  • CBPA
  • PD-1
  • PD-L1
  • cancer immunotherapy
  • small-molecule inhibitor


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