The lack of selective and safe in vivo IRE1α tool molecules has limited the evaluation of IRE1α as a viable target to treat multiple myeloma. Focus on improving the physicochemical properties of a literature compound by decreasing lipophilicity, molecular weight, and basicity allowed the discovery of a novel series with a favorable in vitro safety profile and good oral exposure. These efforts culminated in the identification of a potent and selective in vivo tool compound, G-5758, that was well tolerated following multiday oral administration of doses up to 500 mg/kg. G-5758 demonstrated comparable pharmacodynamic effects to induced IRE1 knockdown as measured by XBP1s levels in a multiple myeloma model (KMS-11).

中文翻译：

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发现有效的、选择性的、口服的 IRE1α 抑制剂，在多发性骨髓瘤模型中展示出与 IRE1 敲低相当的 PD 调节作用

由于缺乏选择性和安全的体内 IRE1α 工具分子，限制了 IRE1α 作为治疗多发性骨髓瘤的可行靶点的评估。专注于通过降低亲脂性、分子量和碱度来改善文献化合物的理化性质，从而发现了具有良好体外安全性和良好口服暴露性的新系列。这些努力最终鉴定出一种有效且选择性的体内工具化合物G-5758，在多日口服剂量高达 500 mg/kg 后具有良好的耐受性。在多发性骨髓瘤模型 (KMS-11) 中通过 XBP1s 水平测量，G-5758表现出与诱导 IRE1 敲低相当的药效学效果。