Subtle Structural Changes across the Boundary between A2AR/A2BR Dual Antagonism and A2BR Antagonism: A Novel Class of 2‑Aminopyrimidine-Based Derivatives

Aberrantly elevated adenosine in the tumor microenvironment exerts its immunosuppressive functions through adenosine receptors A2AR and A2BR. Antagonism of A2AR and A2BR has the potential to suppress tumor growth. Herein, we report a systemic assessment of the effects of an indole modification at position 4, 5, 6, or 7 on both A2AR/A2BR activity and selectivity of novel 2-aminopyrimidine compounds. Substituting indole at the 4-/5-position produced potent A2AR/A2BR dual antagonism, whereas the 6-position of indole substitution gave highly selective A2BR antagonism. Molecular dynamics simulation showed that the 5-cyano compound 7ai had a lower binding free energy than the 6-cyano compound 7aj due to water-bridged hydrogen bond interactions with E169 or F168 in A2AR. Of note, dual A2AR/A2BR antagonism by compound 7ai can profoundly promote the activation and cytotoxic function of T cells. This work provided a strategy for obtaining novel dual A2AR/A2BR or A2BR antagonists by fine-tuning structural modification.

肿瘤微环境中异常升高的腺苷通过腺苷受体A2AR（adenosine A2A receptor）与A2BR（adenosine A2B receptor）发挥免疫抑制功能。靶向拮抗A2AR与A2BR具备抑制肿瘤生长的潜力。本研究系统性评估了在4、5、6或7位进行吲哚修饰，对新型2-氨基嘧啶类化合物的A2AR/A2BR活性与选择性的影响。在4-/5位引入吲哚取代基可获得强效的A2AR/A2BR双重拮抗作用，而在吲哚6位进行取代则可得到高选择性的A2BR拮抗作用。分子动力学模拟（Molecular Dynamics Simulation）结果显示，5位氰基取代化合物7ai相较于6位氰基取代化合物7aj，其结合自由能更低，这源于其与A2AR中E169或F168存在水桥氢键相互作用。值得注意的是，化合物7ai对A2AR/A2BR的双重拮抗作用可显著促进T细胞的活化与细胞毒功能。本研究提出了一种通过精准调控结构修饰，获取新型A2AR/A2BR双重拮抗剂或A2BR拮抗剂的策略。