Deep Human Biology Learning, Eisai Co., Ltd., Tsukuba, Ibaraki, Japan.
Neurology Business Group, Eisai Co., Ltd., Tsukuba, Ibaraki, Japan.
Epilepsia Open. 2023 Sep;8(3):834-845. doi: 10.1002/epi4.12741. Epub 2023 May 18.
As of 2022, 36 anti-seizure medications (ASMs) have been licensed for the treatment of epilepsy, however, adverse effects (AEs) are commonly reported. Therefore, ASMs with a wide margin between therapeutic effects and AEs are preferred over ASMs that are associated with a narrow margin between efficacy and risk of AEs. E2730 was discovered using in vivo phenotypic screening and characterized as an uncompetitive, yet selective, inhibitor of γ-aminobutyric acid (GABA) transporter 1 (GAT1). Here, we describe the preclinical characteristics of E2730.
Anti-seizure effects of E2730 were evaluated in several animal models of epilepsy: corneal kindling, 6 Hz-44 mA psychomotor seizure, amygdala kindling, Fragile X syndrome, and Dravet syndrome models. Effects of E2730 on motor coordination were assessed in accelerating rotarod tests. The mechanism of action of E2730 was explored by [ H]E2730 binding assay. The GAT1-selectivity over other GABA transporters was examined by GABA uptake assay of GAT1, GAT2, GAT3, or betaine/GABA transporter 1 (BGT-1) stably expressing HEK293 cells. To further investigate the mechanism for E2730-mediated inhibition of GAT1, in vivo microdialysis and in vitro GABA uptake assays were conducted under conditions of different GABA concentrations.
E2730 showed anti-seizure effects in the assessed animal models with an approximately >20-fold margin between efficacy and motor incoordination. [ H]E2730 binding on brain synaptosomal membrane was abolished in GAT1-deficient mice, and E2730 selectively inhibited GAT1-mediated GABA uptake over other GABA transporters. In addition, results of GABA uptake assays showed that E2730-mediated inhibition of GAT1 positively correlated to the level of ambient GABA in vitro. E2730 also increased extracellular GABA concentration in hyperactivated conditions but not under basal levels in vivo.
E2730 is a novel, selective, uncompetitive GAT1 inhibitor, which acts selectively under the condition of increasing synaptic activity, contributing to a wide margin between therapeutic effect and motor incoordination.
截至 2022 年，已有 36 种抗癫痫药物 (ASM) 获准用于治疗癫痫，但常报告不良反应 (AE)。因此，与疗效和 AE 风险之间的狭窄范围相关的 ASM 相比，治疗效果和 AE 之间具有较宽范围的 ASM 更受欢迎。E2730 是使用体内表型筛选发现的，并被表征为 γ-氨基丁酸 (GABA) 转运体 1 (GAT1) 的非竞争性但选择性抑制剂。在这里，我们描述了 E2730 的临床前特征。
在几种癫痫动物模型中评估 E2730 的抗癫痫作用：角膜点燃、6 Hz-44 mA 运动性癫痫发作、杏仁核点燃、脆性 X 综合征和 Dravet 综合征模型。通过加速旋转棒测试评估 E2730 对运动协调的影响。通过 [ H]E2730 结合测定探索 E2730 的作用机制。通过 GABA 摄取测定评估 E2730 对其他 GABA 转运体的 GAT1 选择性，GAT1、GAT2、GAT3 或甜菜碱/GABA 转运体 1 (BGT-1) 稳定表达的 HEK293 细胞。为了进一步研究 E2730 介导的 GAT1 抑制的机制，在不同 GABA 浓度下进行了体内微透析和体外 GABA 摄取测定。
E2730 在评估的动物模型中具有抗癫痫作用，其疗效与运动不协调之间的差距约为 20 倍以上。[ H]E2730 在 GAT1 缺陷型小鼠的脑突触体膜上的结合被消除，E2730 选择性抑制 GAT1 介导的 GABA 摄取，而非其他 GABA 转运体。此外，GABA 摄取测定的结果表明，E2730 介导的 GAT1 抑制与体外环境 GABA 水平呈正相关。E2730 还可增加体内过度激活条件下的细胞外 GABA 浓度，但不会增加基础水平。
E2730 是一种新型的选择性非竞争性 GAT1 抑制剂，它在增加突触活动的条件下选择性起作用，在治疗效果和运动不协调之间具有较大的范围。
