In this work, a series of bifunctional PD-L1/CD73 (cluster of differentiation 73) small-molecule inhibitors were designed and synthesized. Among them, CC-5 showed the strongest PD-L1 inhibitory effects with an IC₅₀ of 6 nM and potent anti-CD73 activity with an IC₅₀ of 0.773 μM. The high PD-L1/CD73 inhibitory activity of CC-5 was further confirmed by SPR assays with K_D of 182 nM for human PD-L1 and 101 nM for CD73, respectively. Importantly, CC-5 significantly suppressed tumor growth in a CT26 and B16–F10 tumor model with TGI of 64.3% and 39.6%, respectively. Immunohistochemical (IHC) and flow cytometry analysis of tumor-infiltrating lymphocytes (TILs) indicated that CC-5 exerted anticancer effects via activating the tumor immune microenvironment. Collectively, CC-5 represents the first dual PD-L1/CD73 inhibitor worthy of further research as a bifunctional immunotherapeutic agent.

中文翻译：

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发现针对癌症双重免疫疗法的 PD-L1/CD73 小双功能分子

本工作设计并合成了一系列双功能PD-L1/CD73（分化簇73）小分子抑制剂。其中，CC-5显示出最强的 PD-L1 抑制作用，IC ₅₀为 6 nM，并且具有有效的抗 CD73 活性，IC ₅₀为 0.773 μM。CC-5的高 PD-L1/CD73 抑制活性通过 SPR 测定进一步证实，_人PD-L1 的KD为 182 nM，CD73 的 KD 为 101 nM。重要的是，CC-5显着抑制 CT26 和 B16-F10 肿瘤模型中的肿瘤生长，TGI 分别为 64.3% 和 39.6%。肿瘤浸润淋巴细胞（TIL）的免疫组织化学（IHC）和流式细胞术分析表明CC-5通过激活肿瘤免疫微环境发挥抗癌作用。总的来说，CC-5代表了第一个值得进一步研究的双功能免疫治疗剂 PD-L1/CD73 双重抑制剂。