Prodrugs of a 1‑Hydroxy-2-oxopiperidin-3-yl Phosphonate Enolase Inhibitor for the Treatment of <i>ENO1</i>-Deleted Cancers

Cancers harboring homozygous deletion of the glycolytic enzyme enolase 1 (ENO1) are selectively vulnerable to inhibition of the paralogous isoform, enolase 2 (ENO2). A previous work described the sustained tumor regression activities of a substrate-competitive phosphonate inhibitor of ENO2, 1-hydroxy-2-oxopiperidin-3-yl phosphonate (HEX) (5), and its bis-pivaloyoxymethyl prodrug, POMHEX (6), in an ENO1-deleted intracranial orthotopic xenograft model of glioblastoma [Nature Metabolism 2020, 2, 1423–1426]. Due to poor pharmacokinetics of bis-ester prodrugs, this study was undertaken to identify potential non-esterase prodrugs for further development. Whereas phosphonoamidate esters were efficiently bioactivated in ENO1-deleted glioma cells, McGuigan prodrugs were not. Other strategies, including cycloSal and lipid prodrugs of 5, exhibited low micromolar IC50 values in ENO1-deleted glioma cells and improved stability in human serum over 6. The activity of select prodrugs was also probed using the NCI-60 cell line screen, supporting its use to examine the relationship between prodrugs and cell line-dependent bioactivation.携带糖酵解酶烯醇化酶1（ENO1）纯合缺失的癌症，对其旁系同源同工型烯醇化酶2（ENO2）的抑制呈现选择性敏感性。此前一项研究报道了ENO2的底物竞争性膦酸抑制剂1-羟基-2-氧代哌啶-3-基膦酸酯（HEX，化合物5）及其双新戊酰氧甲酯前药POMHEX（化合物6），在ENO1缺失型胶质母细胞瘤颅内原位异种移植模型中展现出持续的肿瘤消退活性[《自然·代谢》2020, 2, 1423–1426]。鉴于双酯类前药存在药代动力学缺陷，本研究旨在筛选可用于后续开发的非酯酶依赖性前药。研究发现，膦酰胺酯类前药可在ENO1缺失型胶质瘤细胞中被有效生物活化，而麦圭根（McGuigan）前药则无此活性。针对化合物5的其他修饰策略，包括环水杨酸酯（cycloSal）前药与脂质类前药，在ENO1缺失型胶质瘤细胞中展现出低微摩尔级的半最大抑制浓度（IC50），且在人血清中的稳定性优于化合物6。本研究还通过NCI-60细胞系筛选对部分候选前药的活性进行了验证，结果表明该筛选体系可用于探究前药与细胞系依赖型生物活化之间的关联。