Solid tumors are often associated with high levels of extracellular ATP. Ectonucleotidases catalyze the sequential hydrolysis of ATP to adenosine, which potently suppresses T-cell and NK-cell functions via the adenosine receptors (A_2a and A_2b). The ectonucleotidase CD73 catalyzes the conversion of AMP to adenosine. Thus, increased CD73 enzymatic activity in the tumor microenvironment is a potential mechanism for tumor immune evasion and has been associated with poor prognosis in the clinic. CD73 inhibition is anticipated to restore immune function by skirting this major mechanism of adenosine generation. We have developed a series of potent and selective methylenephosphonic acid CD73 inhibitors via a structure-based design. Key binding interactions of the known inhibitor adenosine-5′-(α,β-methylene)diphosphate (AMPCP) with hCD73 provided the foundation for our early designs. The structure–activity relationship study guided by this structure-based design led to the discovery of 4a, which exhibits excellent potency against CD73, exquisite selectivity against related ectonucleotidases, and a favorable pharmacokinetic profile.

中文翻译：

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发现有效和选择性的亚甲基膦酸CD73抑制剂

实体瘤通常与高水平的细胞外ATP相关。外源核酸酶催化ATP顺序水解为腺苷，通过腺苷受体（A _2a和A _2b）有效抑制T细胞和NK细胞功能）。胞外核苷酸酶CD73催化AMP向腺苷的转化。因此，在肿瘤微环境中增加的CD73酶活性是逃避肿瘤免疫的潜在机制，并且与临床预后不良有关。预期通过抑制腺苷生成的这一主要机制，可以抑制CD73来恢复免疫功能。我们已经通过基于结构的设计开发了一系列有效的和选择性的亚甲基膦酸CD73抑制剂。已知抑制剂腺苷5'-（α，β-亚甲基）二磷酸（AMPCP）与hCD73的关键结合相互作用为我们的早期设计奠定了基础。在这种基于结构的设计指导下进行的结构-活动关系研究导致了4a的发现，对CD73表现出优异的效力，对相关的外切核苷酸酶表现出出色的选择性，并具有良好的药代动力学特征。