Targeted next generation sequencing in Chinese colorectal cancer patients guided anti-EGFR treatment and facilitated precision cancer medicine
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Helei Hou1, Dong Liu1, Chuantao Zhang1, Yanxia Jiang2, Guifang Lu3, Na Zhou1, Xiaonan Yang4, Xiaoping Zhang5, Zhuokun Li4, Hongmei Zhu6, Zhaoyang Qian6 and Xiaochun Zhang1
1Department of Medical Oncology, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao, 266005, China
2Department of Pathology, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao, 266005, China
3Department of Gastroenterology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, China
4BGI-Qingdao Institute, Qingdao SINO-GERMAN Ecopark, Qingdao, 266555, China
5Department of Clinical Laboratory, BGI-Shenzhen, Shenzhen, 518083, China
6Binhai Genomics Institute, BGI-Tianjin, BGI-Shenzhen, Tianjin 300308, China
Xiaochun Zhang, email: [email protected]
Keywords: next generation sequencing, colorectal cancer, genetic alteration, targeted therapy, personalized therapy
Received: May 13, 2017 Accepted: August 28, 2017 Published: September 27, 2017
Objective: Colorectal cancer (CRC) patients with both RAS and BRAF wild-type tumors determined by non-next generation sequencing (NGS) testing may still not respond due to the presence of additional mutated genes such as PIK3CA or PTEN. In this study, a broad, hybrid capture-based NGS assay was used to identify RAS, BRAF and additional targetable genetic alterations from Chinese CRC tissues.
Methods: Fifty-seven cases of CRC were enrolled, and all the patients signed the informed consent. In total, 7708 exons of 508 tumor-related genes and 78 introns of 19 frequently rearranged genes were assessed for base substitutions, INDELs, copy number alterations, and gene fusions.
Results: The study found that 50.9% (29/57) of the tumors harbored KRAS mutations, 3.5% (2/57) harbored NRAS mutations and 3.5% (2/57) harbored BRAF mutations. More specifically, 89.7% (26/29) of RAS mutations were located in codon 12. Except for RAS and RAF, anti-EGFR therapy response genetic mutations in PTEN (n=2) and PIK3CA (n=1) were found in 4.7% (3/64) of the samples. Actionable alterations were found in HER2 (n = 7), CCND2 (n = 2), NF1 (n = 1), and BRCA1 (n = 1).
Conclusions: Our results illustrated that 82.5% (47/57) of the samples harbored at least one actionable genetic alteration identified by NGS. HER2 amplifications or mutations, which were identified in 12.3% of the tissues, defined a unique molecular subtype of CRC. The study suggests that high-throughput NGS testing in CRC tissues is a comprehensive and efficient genomic profiling assay to guide personalized therapy.
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