Inactive state-selective KRAS(G12C) inhibitors^{1,2,3,4,5,6,7,8} demonstrate a 30–40% response rate and result in approximately 6-month median progression-free survival in patients with lung cancer⁹. The genetic basis for resistance to these first-in-class mutant GTPase inhibitors remains under investigation. Here we evaluated matched pre-treatment and post-treatment specimens from 43 patients treated with the KRAS(G12C) inhibitor sotorasib. Multiple treatment-emergent alterations were observed across 27 patients, including alterations in KRAS, NRAS, BRAF, EGFR, FGFR2, MYC and other genes. In preclinical patient-derived xenograft and cell line models, resistance to KRAS(G12C) inhibition was associated with low allele frequency hotspot mutations in KRAS(G12V or G13D), NRAS(Q61K or G13R), MRAS(Q71R) and/or BRAF(G596R), mirroring observations in patients. Single-cell sequencing in an isogenic lineage identified secondary RAS and/or BRAF mutations in the same cells as KRAS(G12C), where they bypassed inhibition without affecting target inactivation. Genetic or pharmacological targeting of ERK signalling intermediates enhanced the antiproliferative effect of G12C inhibitor treatment in models with acquired RAS or BRAF mutations. Our study thus suggests a heterogenous pattern of resistance with multiple subclonal events emerging during G12C inhibitor treatment. A subset of patients in our cohort acquired oncogenic KRAS, NRAS or BRAF mutations, and resistance in this setting may be delayed by co-targeting of ERK signalling intermediates. These findings merit broader evaluation in prospective clinical trials.

非活性状态选择性 KRAS(G12C) 抑制剂^{1,2,3,4,5,6,7,8}显示出 30-40% 的缓解率，并导致肺癌患者的中位无进展生存期约为 6 个月⁹ 。对这些一流的突变型 GTP 酶抑制剂产生耐药性的遗传基础仍在研究中。在这里，我们评估了 43 名接受 KRAS(G12C) 抑制剂 sotorasib 治疗的患者的匹配治疗前和治疗后标本。在 27 名患者中观察到多种治疗引起的改变，包括KRAS 、 NRAS 、 BRAF 、 EGFR 、 FGFR2 、 MYC和其他基因的改变。在临床前患者来源的异种移植和细胞系模型中，对 KRAS（G12C）抑制的耐药性与 KRAS（G12V 或 G13D）、NRAS（Q61K 或 G13R）、MRAS（Q71R）和/或 BRAF 中的低等位基因频率热点突变相关。 G596R），反映了患者的观察结果。同基因谱系中的单细胞测序鉴定出与 KRAS（G12C）相同的细胞中的二次 RAS 和/或 BRAF 突变，它们绕过了抑制而不影响靶标失活。在具有获得性 RAS 或 BRAF 突变的模型中，ERK 信号中间体的遗传或药理学靶向增强了 G12C 抑制剂治疗的抗增殖作用。因此，我们的研究表明在 G12C 抑制剂治疗期间出现了多种亚克隆事件的异质耐药模式。我们队列中的一部分患者获得了致癌 KRAS、NRAS 或 BRAF 突变，这种情况下的耐药性可能会通过 ERK 信号传导中间体的共同靶向来延迟。这些发现值得在前瞻性临床试验中进行更广泛的评估。