Circulating tumor DNA (ctDNA) is the cornerstone of liquid biopsy diagnostics, revealing clinically relevant genomic aberrations from blood of cancer patients. Genomic analysis of single circulating tumor cells (CTCs) could provide additional insights into intra-patient heterogeneity, but it requires whole-genome amplification (WGA) of DNA, which might introduce bias. Here, we describe a novel approach based on mass spectrometry for mutation detection from individual CTCs not requiring WGA and complex bioinformatics pipelines. After establishment of our protocol on tumor cell line-derived single cells, it was validated on CTCs of 33 metastatic melanoma patients and the mutations were compared to those obtained from tumor tissue and ctDNA. Although concordance with tumor tissue was superior for ctDNA over CTC analysis, a larger number of mutations were found within CTCs compared to ctDNA (p = 0.039), including mutations in melanoma driver genes, or those associated with resistance to therapy or metastasis. Thus, our results demonstrate proof-of-principle data that CTC analysis can provide clinically relevant genomic information that is not redundant to tumor tissue or ctDNA analysis.

中文翻译：

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单个循环肿瘤细胞的突变分析描述了黑色素瘤的肿瘤内异质性。


循环肿瘤 DNA （ctDNA） 是液体活检诊断的基石，可揭示癌症患者血液中的临床相关基因组畸变。单个循环肿瘤细胞 （CTC） 的基因组分析可以提供对患者内部异质性的额外见解，但它需要 DNA 的全基因组扩增 （WGA），这可能会引入偏倚。在这里，我们描述了一种基于质谱的新方法，用于从不需要 WGA 和复杂生物信息学管道的单个 CTC 中检测突变。在肿瘤细胞系来源的单细胞上建立我们的方案后，它在 33 名转移性黑色素瘤患者的 CTC 上进行了验证，并将突变与从肿瘤组织和 ctDNA 获得的突变进行了比较。尽管 ctDNA 与肿瘤组织的一致性优于 CTC 分析，但与 ctDNA 相比，CTC 中发现的突变数量更多 （p = 0.039），包括黑色素瘤驱动基因的突变，或与治疗耐药性或转移相关的突变。因此，我们的结果证明了原理验证数据，即 CTC 分析可以提供临床相关的基因组信息，这些信息对于肿瘤组织或 ctDNA 分析来说不是多余的。