Novel covalent warhead imparts potent activity against both GDP- and GTP-bound forms of KRAS G12C

The discovery of KRAS G12C inactive state inhibitors represents a significant advancement in the field of precision oncology. While inactive state inhibition shows promise in patients, SWII-binding inhibitors targeting both inactive and active states remain an underdeveloped therapeutic modality. Here, we describe the discovery of KRAS G12C dual inhibitors that bind the SWII allosteric site using a chemically differentiated warhead to covalently modify both KRAS G12C inactive and active states. Co-crystal structures reveal that these inhibitors perturb a key water-mediated hydrogen bonding network and trigger allosteric remodeling of the GTP-bound protein surface and Switch I to prevent binding to downstream effectors. Consistent with simultaneous targeting of the active and inactive state, dual inhibitors provide rapid covalent target engagement and suppression of MAPK signaling. However, KRAS G12C dual and inactive state inhibitors demonstrate similar efficacy in cellular and in vivo models despite faster target inhibition afforded by targeting the active state. Furthermore, KRAS G12C dual and inactive state inhibitors show similar cellular efficacy in the presence of growth factors that drive KRAS, wt NRAS and wt HRAS to the active state. These data provide the first detailed account of targeting the active and inactive state of KRAS and highlight the absence of a mechanistic advantage in the context of prolonged KRAS G12C inhibition and efficacy.

KRAS G12C非活性态抑制剂的发现，代表了精准肿瘤学领域的一项重大进展。尽管非活性态抑制剂在临床患者中已展现出应用潜力，但同时靶向KRAS G12C非活性与活性态的开关II（SWII）结合型抑制剂，仍是一种尚未充分开发的治疗手段。本研究报道了一类靶向SWII变构位点的KRAS G12C双态抑制剂：此类抑制剂采用化学特征独特的弹头基团，可对KRAS G12C的非活性与活性态同时进行共价修饰。共晶结构解析结果显示，此类抑制剂可扰乱关键的水介导氢键网络，并触发GTP结合蛋白表面与开关I（Switch I）区域的变构重塑，从而阻断其与下游效应蛋白的结合。由于可同时靶向活性与非活性态，此类双态抑制剂能够实现快速的共价靶标结合，并抑制丝裂原活化蛋白激酶（MAPK）信号通路。然而，尽管靶向活性态可实现更快的靶标抑制，但KRAS G12C双态抑制剂与非活性态抑制剂在细胞与体内模型中展现出相似的疗效。此外，在可驱动KRAS、野生型NRAS与野生型HRAS转变为活性态的生长因子存在的条件下，KRAS G12C双态抑制剂与非活性态抑制剂的细胞疗效仍保持一致。本研究首次详细阐述了同时靶向KRAS活性与非活性态的策略，并指出在长期KRAS G12C抑制的场景下，此类双态抑制剂并未展现出机制层面的疗效优势。