Current small-molecule inhibitors of KRAS(G12C) bind irreversibly in the switch-II pocket (SII-P), exploiting the strong nucleophilicity of the acquired cysteine as well as the preponderance of the GDP-bound form of this mutant. Nevertheless, many oncogenic KRAS mutants lack these two features, and it remains unknown whether targeting the SII-P is a practical therapeutic approach for KRAS mutants beyond G12C. Here we use NMR spectroscopy and a cellular KRAS engagement assay to address this question by examining a collection of SII-P ligands from the literature and from our own laboratory. We show that the SII-Ps of many KRAS hotspot (G12, G13, Q61) mutants are accessible using noncovalent ligands, and that this accessibility is not necessarily coupled to the GDP state of KRAS. The results we describe here emphasize the SII-P as a privileged drug-binding site on KRAS and unveil new therapeutic opportunities in RAS-driven cancer.

目前的 KRAS(G12C) 小分子抑制剂在 switch-II 口袋 (SII-P) 中不可逆地结合，利用获得的半胱氨酸的强亲核性以及该突变体的 GDP 结合形式的优势。然而，许多致癌的 KRAS 突变体缺乏这两个特征，并且目前尚不清楚靶向 SII-P 是否是 G12C 以外的 KRAS 突变体的实用治疗方法。在这里，我们使用核磁共振光谱和细胞 KRAS 结合测定通过检查文献和我们自己实验室的 SII-P 配体集合来解决这个问题。我们表明许多 KRAS 热点（G12、G13、Q61）突变体的 SII-P 可使用非共价配体访问，并且这种可访问性不一定与 KRAS 的 GDP 状态耦合。