Yang Xuanhua, Feng Shiwei, Zhang Qi, Li Wenxin, Li Shujuan, Zhi Min, Lan Ping, Cheng Sijing
Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital, Sun Yat-Sen University, 26 Yuancun Erheng Road, Guangzhou, 510655, People's Republic of China.
Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510655, People's Republic of China.
J Transl Med. 2025 Jul 24;23(1):824. doi: 10.1186/s12967-025-06864-x.
Kirsten Rat Sarcoma (KRAS) copy number amplification has emerged as an oncogenic driver in colorectal cancer (CRC), in addition to KRAS mutation. However, its clinical significance remains poorly understood. Notably, CRC patients with wild-type KRAS but harboring KRAS amplification have shown resistance to anti-EGFR therapy, representing an unmet clinical need.
In this study, we comprehensively investigated the impact of KRAS amplification-alone and in conjunction with mutation-on clinicopathological characteristics, immune infiltration, and therapeutic response. KRAS copy number variation (CNV) was classified into amplification and non-amplification groups. KRAS mutational status was determined as wild-type (WT) or mutant (MUT) using qPCR and Sanger sequencing. CD8⁺ T lymphocyte infiltration was evaluated by immunohistochemistry in resected CRC specimens. Clinical, immune, and survival data were analyzed in association with KRAS status. RNA-seq was performed to identify differentially expressed genes (DEGs) and enriched pathways. Patient-derived xenograft (PDX) models were used to assess responses to targeted therapies.
We found that KRAS amplification was more frequent in WT KRAS CRC (21.4%) than in MUT KRAS CRC (6.5%). In the WT subgroup, KRAS amplification was associated with poor prognosis and increased KRAS protein expression and downstream pathway activation. In contrast, amplification had little effect in mutant KRAS tumors. KRAS copy number was inversely correlated with CD8⁺ T cell infiltration, suggesting a role in immune evasion. Importantly, low CD8⁺ T cell density combined with KRAS amplification predicted adverse outcomes. Therapeutically, KRAS-amplified PDX models were resistant to anti-EGFR treatment. However, combined MEK and CDK4/6 inhibition overcame this resistance.
KRAS amplification constitutes a distinct oncogenic driver in CRC and a potential biomarker for therapeutic stratification. Our findings support the clinical rationale for dual MEK and CDK4/6 inhibition in KRAS-amplified CRC and highlight the need for biomarker-guided clinical trials to optimize treatment strategies in this subset of patients.
除了KRAS突变外， Kirsten大鼠肉瘤（KRAS）拷贝数扩增已成为结直肠癌（CRC）的致癌驱动因素。然而，其临床意义仍知之甚少。值得注意的是，野生型KRAS但携带KRAS扩增的CRC患者已显示出对抗表皮生长因子受体（anti-EGFR）治疗的耐药性，这代表了未满足的临床需求。
在本研究中，我们全面研究了单独KRAS扩增以及与突变联合对临床病理特征、免疫浸润和治疗反应的影响。KRAS拷贝数变异（CNV）分为扩增组和非扩增组。使用定量聚合酶链反应（qPCR）和桑格测序将KRAS突变状态确定为野生型（WT）或突变型（MUT）。通过免疫组织化学在切除的CRC标本中评估CD8⁺T淋巴细胞浸润。结合KRAS状态分析临床、免疫和生存数据。进行RNA测序以鉴定差异表达基因（DEG）和富集途径。使用患者来源的异种移植（PDX）模型评估对靶向治疗的反应。
我们发现野生型KRAS CRC中KRAS扩增（21.4%）比突变型KRAS CRC（6.5%）更频繁。在野生型亚组中，KRAS扩增与预后不良、KRAS蛋白表达增加和下游途径激活相关。相比之下，扩增在突变型KRAS肿瘤中影响很小。KRAS拷贝数与CD8⁺T细胞浸润呈负相关，表明其在免疫逃逸中起作用。重要的是，低CD8⁺T细胞密度与KRAS扩增相结合预示不良结局。在治疗上，KRAS扩增的PDX模型对抗EGFR治疗耐药。然而，联合MEK和CDK4/6抑制克服了这种耐药性。
KRAS扩增是CRC中一种独特的致癌驱动因素，也是治疗分层的潜在生物标志物。我们的研究结果支持在KRAS扩增的CRC中联合MEK和CDK4/6抑制的临床理论依据，并强调需要进行生物标志物指导的临床试验以优化该亚组患者的治疗策略。
