基于循环游离DNA的染色体不稳定检测与转移性胃癌患者化疗应答相关性研究

Correlation between chromosome instability detection based on circulating free DNA and chemotherapy response in patients with metastatic gastric cancer

目的通过对转移性胃癌患者进行低覆盖度全基因组测序,探索胃癌化疗耐药的发生发展和基因组学变化。方法收集2019年7—12月就诊于同济大学附属第十人民医院的9例转移性胃癌患者。在化疗前后收集外周血标本,提取血浆循环游离DNA(cfDNA)进行低覆盖率的全基因组测序,并通过超灵敏染色体不稳定性检测(UCAD)进行染色体不稳定分析。结果根据化疗后的疗效评估将患者分为化疗有效组和化疗无效组。化疗有效组治疗后染色体不稳定水平低于治疗前[(1.186±1.642)%∶(5.639±7.666)%,P=0.017],化疗无效组治疗后染色体不稳定水平似乎高于治疗前(0.11%∶0.08%)。UCAD检测提示频繁的染色体拷贝数变化包括7p、8q、10q、11q、12q、17q增加,8p、17p缺失等。比较化疗前后的染色体拷贝数变化,2例(22.2%)患者在化疗后出现额外的拷贝数增加,包括11q、5p拷贝数增多,进一步疗效分析表明化疗耐药。结论基于血浆cfDNA的染色体不稳定动态检测有望作为转移性胃癌疗效评估和化疗耐药性产生的生物标志物。

Objective Low coverage whole genome sequencing was performed on patients with metastatic gastric adenocarcinoma to explore the occurrence,development and genomic changes of chemotherapy resistance in gastric cancer.Methods Nine patients with gastric adenocarcinoma were recruited since July to December 2019 in Tenth People's Hospital Affiliated to Tongji University.Peripheral blood samples were collected before and after chemotherapy.Plasma cfDNA(circulating free DNA)was isolated and send to low-coverage genome-wide sequencing,followed by chromosomal instability(CIN)analyses by a customized workflow ultrasensitive chromosomal aneuploidy detection(UCAD).Results According to the efficacy of chemotherapy,the patients were divided into two groups,the chemotherapy effective group and the chemotherapy ineffective group.The level of CIN after treatment was lower than that before in the chemotherapy effective group[(1.186±1.642)%:(5.639±7.666)%,P=0.017].The level of CIN after treatment was seemingly higher than that before in the chemotherapy ineffective group(0.11%:0.08%).Frequent chromosomal copy number variations included 7p,8q,10q,11q,12p,17q gain,8p loss,17p loss,et al.Two(22.2%)patients were found with additional copy number gains after chemotherapy,including 11q gain,and 5p gain.Further analyses showed those patients were treatment resistance.Conclusions Dynamic detection of chromosomal instability based on plasma cfDNA might be used as a predictive biomarker to evaluate the efficacy of metastatic gastric cancer and the emergence of chemotherapy resistance.