The ability to restrict low molecular weight compounds to the gastrointestinal (GI) tract may enable an enhanced therapeutic index for molecular targets known to be associated with systemic toxicity. Using a triazolopyrazine CSF1R inhibitor scaffold, a broad range of prodrugs were synthesized and evaluated for enhanced delivery to the colon in mice. Subsequently, the preferred cyclodextrin prodrug moiety was appended to a number of CSF1R inhibitory active parent molecules, enabling GI-restricted delivery. Evaluation of a cyclodextrin prodrug in a dextran sodium sulfate (DSS)-induced mouse colitis model resulted in enhanced GI tissue levels of active parent. At a dose where no significant depletion of systemic monocytes were detected, the degree of pharmacodynamic effect–measured as reduction in macrophages in the colon–was inferior to that observed with a systemically available positive control. This suggests that a suitable therapeutic index cannot be achieved with CSF1R inhibition by using GI-restricted delivery in mice. However, these efforts provide a comprehensive frame-work in which to pursue additional gut-restricted delivery strategies for future GI targets.
能够限制低分子量化合物在胃肠道(GI)中的能力,可能为已知与全身毒性相关的分子靶点带来增强的治疗指数。利用三唑
吡嗪CSF1R
抑制剂骨架,合成了一系列前药,并对其在小鼠结肠中的增强递送进行了评估。随后,在多个具有CSF1R抑制活性的母体分子上附加了首选的
环糊精前药部分,实现了GI限制性递送。在一项
葡聚糖硫酸钠(DSS)引发的小鼠结肠炎模型中对
环糊精前药进行评估,结果显示活性母体在GI组织中的
水平得到了增强。在未检测到系统性单核细胞显著减少的剂量下,药效学效应的程度(以结肠中巨噬细胞减少为衡量标准)不及系统性可用的阳性对照组所观察到的效果。这表明,在小鼠中通过GI限制性递送无法实现合适的治疗指数。然而,这些努力提供了一个全面的框架,以便在未来针对胃肠道目标探索其他肠道限制性递送策略。