561P - Targeted sequencing of plasma ctDNAs and primary tumors identified heterogeneity and homogeneity in advanced gastric cancer

Date 17 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Gastric Cancer
Translational Research
Presenter Jing Gao
Citation Annals of Oncology (2016) 27 (suppl_9): ix181-ix183. 10.1093/annonc/mdw602
Authors J. Gao
  • Gastrointestinal Oncology, Peking University Cancer Hospital-Beijing Cancer Hospital, 100142 - Beijing/CN

Abstract

Background

The emerging marker for liquid biopsy, circulating tumor DNAs (ctDNAs) play potential roles in tumor diagnosis and monitoring of the therapeutic response or disease progression. Furthermore, ctDNA is expected to overcome tumor heterogeneity, which is unclear in gastric cancer.

Methods

Targeted next-generation sequencing (NGS) was performed to understand the genomic profiles of plasma ctDNAs and paired primary tumors in 39 patients with advanced gastric cancer (AGC) treated in our department between April 2010 and October 2014.

Results

The genomic alterations between plasma ctDNAs and paired tumor tissues identified by NGS exhibited consistency and discordance, and intra- and intertumoral heterogeneity to varying degrees were frequent in gastric cancer and could be partially overcome by plasma ctDNAs. HER2 amplification could be successfully identified in plasma ctDNAs, and good HER2 amplification concordance (94.9%, k = 0.866, P = 0.000) was seen between tumor tissues and matched plasma ctDNAs, suggesting the potential use of plasma ctDNAs in clinical practice to guide targeted therapy. Compared to tumor tissues, TP53 mutation in the plasma was more closely related to patient prognosis independent of clinicopathological features and therapy, which was consistent with the result reported by the Asian Cancer Research Group.

Conclusions

NGS of plasma ctDNAs and primary tumors could provide insight into heterogeneity and homogeneity in AGC, and plasma ctDNA could partially overcome tumor heterogeneity. Our results imply that tumor tissues and paired plasmas could be complementary and that both should be detected in the future era of precision medicine.

Clinical trial indentification

Legal entity responsible for the study

Beijing Cancer Hospital

Funding

National Basic Research Program of China

Disclosure

All authors have declared no conflicts of interest.