Recent progress in targeting KRAS^G12C has provided both insight and inspiration for targeting alternative KRAS mutants. In this study, we evaluated the mechanism of action and anti-tumor efficacy of MRTX1133, a potent, selective and non-covalent KRAS^G12D inhibitor. MRTX1133 demonstrated a high-affinity interaction with GDP-loaded KRAS^G12D with K_D and IC₅₀ values of ~0.2 pM and <2 nM, respectively, and ~700-fold selectivity for binding to KRAS^G12D as compared to KRAS^WT. MRTX1133 also demonstrated potent inhibition of activated KRAS^G12D based on biochemical and co-crystal structural analyses. MRTX1133 inhibited ERK1/2 phosphorylation and cell viability in KRAS^G12D-mutant cell lines, with median IC₅₀ values of ~5 nM, and demonstrated >1,000-fold selectivity compared to KRAS^WT cell lines. MRTX1133 exhibited dose-dependent inhibition of KRAS-mediated signal transduction and marked tumor regression (≥30%) in a subset of KRAS^G12D-mutant cell-line-derived and patient-derived xenograft models, including eight of 11 (73%) pancreatic ductal adenocarcinoma (PDAC) models. Pharmacological and CRISPR-based screens demonstrated that co-targeting KRAS^G12D with putative feedback or bypass pathways, including EGFR or PI3Kα, led to enhanced anti-tumor activity. Together, these data indicate the feasibility of selectively targeting KRAS mutants with non-covalent, high-affinity small molecules and illustrate the therapeutic susceptibility and broad dependence of KRAS^G12D mutation-positive tumors on mutant KRAS for tumor cell growth and survival.

^{靶向 KRAS G12C}的最新进展为靶向替代 KRAS 突变体提供了见解和灵感。在这项研究中，我们评估了 MRTX1133 的作用机制和抗肿瘤功效，MRTX1133 是一种有效的、选择性的和非共价的 KRAS ^G12D抑制剂。^{MRTX1133 展示了与负载 GDP 的 KRAS G12D}的高亲和力相互作用，K D_和IC _{50值分别为~0.2 pM 和<2 nM，与 KRAS} ^WT相比，与KRAS ^G12D结合的选择性为~700 倍。^{MRTX1133 还显示出对激活的 KRAS G12D}的有效抑制基于生化和共晶结构分析。MRTX1133 抑制KRAS ^G12D突变细胞系中的 ERK1/2 磷酸化和细胞活力，中值 IC ₅₀值为 ~5 nM，与KRAS ^WT细胞系相比，选择性超过 1,000 倍。MRTX1133 在KRAS ^G12D突变细胞系衍生和患者衍生的异种移植模型的一个子集中表现出对 KRAS 介导的信号转导的剂量依赖性抑制和显着的肿瘤消退（≥30%） ，包括 11 个胰腺模型中的 8 个（73%）导管腺癌 (PDAC) 模型。药理学和基于 CRISPR 的筛选表明，共同靶向 KRAS ^G12D具有推定的反馈或旁路通路，包括 EGFR 或 PI3Kα，导致增强的抗肿瘤活性。总之，这些数据表明使用非共价、高亲和力小分子选择性靶向 KRAS 突变体的可行性，并说明KRAS ^G12D突变阳性肿瘤对肿瘤细胞生长和存活的突变体 KRAS 的治疗敏感性和广泛依赖性。