Payne Rachel E, Yagüe Ernesto, Slade Martin J, Apostolopoulos Christos, Jiao Long R, Ward Becky, Coombes R Charles, Stebbing Justin
Department of Oncology, Imperial College London, Du Cane Road, London W12 ONN, UK.
Pharmacogenomics. 2009 Jan;10(1):51-7. doi: 10.2217/14622416.10.1.51.
Studies of EGFR expression in breast cancer have shown inconsistent results due in part to a large range of methods used. Anti-EGFR therapy trials have often not used patient selection because of this. We describe the use of the CellSearch system (Veridex LLC, NJ, USA) to enumerate and measure EGFR expression on the surface of circulating tumor cells (CTCs), derived from the peripheral blood of individuals with metastatic breast cancer over time.
MATERIALS & METHODS: The CellSearch system was used to quantify CTCs and EGFR measurement was performed on all samples. The specificity of EGFR phenotyping was further examined by spiking with cell lines with increased and low (or absent) levels of EGFR expression using the CellSearch system to enrich and phenotype the CTCs.
Serial samples were obtained from 33 individuals with metastatic breast cancer. CTCs derived from these individuals had consistent levels of EGFR expression at different time points, and none of the patients 'switched' from a positive to negative EGFR phenotype or vice versa. The specificity of EGFR phenotyping by the CellSearch system was verified by staining of EGFR only being present in a high EGFR expressing EGFR cell line (MDA-MB-468), as confirmed by Western blotting.
Measurement of EGFR on the surface of CTCs, derived from individuals with metastatic breast cancer patients is possible using the CellSearch system and showed consistent positivity over time. The use of this system will now be validated in a prospective study aiming to identify patients for anti-EGFR therapy based on the expression profile of CTCs.
乳腺癌中表皮生长因子受体（EGFR）表达的研究结果并不一致，部分原因是所使用的方法范围广泛。因此，抗EGFR治疗试验通常未进行患者选择。我们描述了使用CellSearch系统（美国新泽西州Veridex有限责任公司）来计数和测量转移性乳腺癌患者外周血中循环肿瘤细胞（CTC）表面的EGFR表达，该表达随时间变化。
使用CellSearch系统对CTC进行定量，并对所有样本进行EGFR测量。通过添加EGFR表达水平升高和降低（或无表达）的细胞系，利用CellSearch系统富集和鉴定CTC，进一步检测EGFR表型分析的特异性。
从33例转移性乳腺癌患者中获取系列样本。这些患者来源的CTC在不同时间点的EGFR表达水平一致，且没有患者从EGFR表型阳性转变为阴性，反之亦然。通过蛋白质免疫印迹法证实，仅在高表达EGFR的细胞系（MDA-MB-468）中存在EGFR染色，从而验证了CellSearch系统对EGFR表型分析的特异性。
使用CellSearch系统可以测量转移性乳腺癌患者来源的CTC表面的EGFR，且随时间推移显示出一致的阳性结果。该系统的应用现将于一项前瞻性研究中得到验证，该研究旨在根据CTC的表达谱识别适合抗EGFR治疗的患者。
