INSERM U981, Institut Gustave Roussy, Université Paris-Saclay, Villejuif, France; INSERM US23 AMMICA, Institut Gustave Roussy, Université Paris-Saclay, Villejuif, France.
INSERM U981, Institut Gustave Roussy, Université Paris-Saclay, Villejuif, France.
Eur Urol Oncol. 2020 Aug;3(4):498-508. doi: 10.1016/j.euo.2018.12.005. Epub 2019 Jan 4.
Genomic analysis of circulating tumor cells (CTCs) could provide a unique and accessible representation of tumor diversity but remains hindered by technical challenges associated with CTC rarity and heterogeneity.
To evaluate CTCs as surrogate samples for genomic analyses in metastatic castration-resistant prostate cancer (mCRPC).
DESIGN, SETTING, AND PARTICIPANTS: Three isolation strategies (filter laser-capture microdissection, self-seeding microwell chips, and fluorescence-activated cell sorting) were developed to capture CTCs with various epithelial and mesenchymal phenotypes and isolate them at the single-cell level. Whole-genome amplification (WGA) and WGA quality control were performed on 179 CTC samples, matched metastasis biopsies, and negative controls from 11 patients. All patients but one were pretreated with enzalutamide or abiraterone. Whole-exome sequencing (WES) of 34 CTC samples, metastasis biopsies, and negative controls were performed for seven patients.
WES of CTCs was rigorously qualified in terms of percentage coverage at 10× depth, allelic dropout, and uncovered regions. Shared somatic mutations between CTCs and matched metastasis biopsies were identified. A customized approach based on determination of mutation rates for CTC samples was developed for identification of CTC-exclusive mutations.
Shared mutations were mostly detected in epithelial CTCs and were recurrent. For two patients for whom a deeper analysis was performed, a few CTCs were sufficient to represent half to one-third of the mutations in the matched metastasis biopsy. CTC-exclusive mutations were identified in both epithelial and nonepithelial CTCs and affected cytoskeleton, invasion, DNA repair, and cancer-driver genes. Some 41% of CTC-exclusive mutations had a predicted deleterious impact on protein function. Phylogenic relationships between CTCs with distinct phenotypes were evidenced.
CTCs can provide unique insight into metastasis mutational diversity and reveal undiagnosed genomic aberrations in matched metastasis biopsies.
Our results demonstrate the clinical potential of circulating tumor cells to provide insight into metastatic events that could be critical to target using precision medicine.
循环肿瘤细胞（CTC）的基因组分析可为肿瘤异质性提供独特且易于获取的代表性，但仍受到与 CTC 稀有性和异质性相关的技术挑战的阻碍。
评估 CTC 作为转移性去势抵抗性前列腺癌（mCRPC）基因组分析的替代样本。
设计、设置和参与者：开发了三种分离策略（滤膜激光捕获微切割、自播种微井芯片和荧光激活细胞分选），以捕获具有不同上皮和间充质表型的 CTC，并在单细胞水平上对其进行分离。对 11 名患者的 179 个 CTC 样本、转移性活检和阴性对照进行了全基因组扩增（WGA）和 WGA 质量控制。对 7 名患者的 34 个 CTC 样本、转移性活检和阴性对照进行了全外显子组测序（WES）。
对 CTC 进行了严格的 WES 质量评估，包括 10×深度的覆盖率、等位基因缺失和未覆盖区域。确定了 CTC 和匹配的转移活检之间的共享体细胞突变。为了识别 CTC 独有的突变，开发了一种基于确定 CTC 样本突变率的定制方法。
主要在上皮 CTC 中检测到共享突变，且为复发性突变。对于两名进行了更深入分析的患者，少数 CTC 就足以代表匹配转移活检中一半到三分之一的突变。在上皮和非上皮 CTC 中均鉴定出 CTC 独有的突变，并影响细胞骨架、侵袭、DNA 修复和癌症驱动基因。大约 41%的 CTC 独有的突变对蛋白质功能有预测的有害影响。证据表明，具有不同表型的 CTC 之间存在系统发育关系。
CTC 可提供有关转移突变多样性的独特见解，并揭示匹配转移活检中未诊断的基因组异常。
我们的结果表明，循环肿瘤细胞具有提供对转移性事件的洞察力的临床潜力，这对于使用精准医学靶向治疗可能至关重要。
