Shoda Katsutoshi, Masuda Kiyoshi, Ichikawa Daisuke, Arita Tomohiro, Miyakami Yuko, Watanabe Miki, Konishi Hirotaka, Imoto Issei, Otsuji Eigo
Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, 465 Kawaramach Hirokoji Kajiicho, Kamigyo-ku, Kyoto, 602-8566, Japan.
Department of Human Genetics, Institute of Health Biosciences, University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan.
Gastric Cancer. 2015 Oct;18(4):698-710. doi: 10.1007/s10120-014-0432-5. Epub 2014 Oct 17.
We used real-time quantitative polymerase chain reaction (rqPCR) to detect human epidermal growth factor receptor 2 (HER2) amplification in the circulating cell-free DNA (cfDNA) of patients with gastric cancer (GC), which shows the spatial and temporal intrinsic heterogeneity of HER2 expression/copy number during progression, for liquid biopsy and treatment monitoring.
We first enrolled 52 patients with advanced GC who underwent surgery and 40 healthy volunteers. For patients with GC, plasma cfDNA was obtained before surgery (43 patients) and during postoperative treatment (nine of 43 patients). After ribonuclease P RNA component H1 (RPPH1) had been selected as a reference gene for HER2 CN assessment by rqPCR in GC tumours and plasma, plasma HER2-to-RPPH1 ratios were determined retrospectively in a development cohort and an additional independent validation cohort.
The HER2-to-RPPH1 ratio of GC tissues determined by rqPCR was concordant with routinely determined HER2 status. The plasma HER2-to-RPPH1 ratio was significantly higher for patients with HER2-positive tumours than for those with HER2-negative tumours. The sensitivity and specificity of the plasma HER2-to-RPPH1 ratio test were 0.539 and 0.967, respectively, in the development cohort, and 0.667 and 1.000, respectively, in the validation cohort. HER2 amplifications acquired and lost during tumour progression and treatment, respectively, were apparently detected by repeated assessments of plasma HER2-to-RPPH1 ratios during postoperative treatment.
Our preliminary data demonstrated the potential clinical use of circulating cfDNA to detect HER2 amplification as a therapeutic marker to detect and monitor HER2 CN status for effective molecular targeted therapy in patients with GC.
我们使用实时定量聚合酶链反应（rqPCR）检测胃癌（GC）患者循环游离DNA（cfDNA）中的人表皮生长因子受体2（HER2）扩增情况，以显示疾病进展过程中HER2表达/拷贝数的时空内在异质性，用于液体活检和治疗监测。
我们首先招募了52例接受手术的晚期GC患者和40名健康志愿者。对于GC患者，在手术前（43例患者）和术后治疗期间（43例患者中的9例）获取血浆cfDNA。在选择核糖核酸酶P RNA组分H1（RPPH1）作为GC肿瘤和血浆中rqPCR评估HER2拷贝数的参考基因后，在一个开发队列和另一个独立验证队列中回顾性测定血浆HER2与RPPH1的比值。
通过rqPCR测定的GC组织中HER2与RPPH1的比值与常规测定的HER2状态一致。HER2阳性肿瘤患者的血浆HER2与RPPH1比值显著高于HER2阴性肿瘤患者。在开发队列中，血浆HER2与RPPH1比值检测的敏感性和特异性分别为0.539和0.967，在验证队列中分别为0.667和1.000。术后治疗期间通过重复评估血浆HER2与RPPH1比值，分别明显检测到肿瘤进展和治疗过程中获得和丢失的HER2扩增。
我们的初步数据证明了循环cfDNA在检测HER2扩增方面的潜在临床应用价值，可以作为一种治疗标志物来检测和监测GC患者的HER2拷贝数状态，以进行有效的分子靶向治疗。
