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J Clin Invest. 2014 Dec;124(12):5145-58. doi: 10.1172/JCI75200. Epub 2014 Nov 17.

Preexisting oncogenic events impact trastuzumab sensitivity in ERBB2-amplified gastroesophageal adenocarcinoma.

Abstract

Patients with gastric and esophageal (GE) adenocarcinoma tumors in which the oncogene ERBB2 has been amplified are routinely treated with a combination of cytotoxic chemotherapy and the ERBB2-directed antibody trastuzumab; however, the addition of trastuzumab, even when tested in a selected biomarker-positive patient population, provides only modest survival gains. To investigate the potential reasons for the modest impact of ERBB2-directed therapies, we explored the hypothesis that secondary molecular features of ERBB2-amplified GE adenocarcinomas attenuate the impact of ERBB2 blockade. We analyzed genomic profiles of ERBB2-amplified GE adenocarcinomas and determined that the majority of ERBB2-amplified tumors harbor secondary oncogenic alterations that have the potential to be therapeutically targeted. These secondary events spanned genes involved in cell-cycle regulation as well as phosphatidylinositol-3 kinase and receptor tyrosine kinase signaling. Using ERBB2-amplified cell lines, we demonstrated that secondary oncogenic events could confer resistance to ERBB2-directed therapies. Moreover, this resistance could be overcome by targeting the secondary oncogene in conjunction with ERBB2-directed therapy. EGFR is commonly coamplified with ERBB2, and in the setting of ERBB2 amplification, higher EGFR expression appears to mark tumors with greater sensitivity to dual EGFR/ERBB2 kinase inhibitors. These data suggest that combination inhibitor strategies, guided by secondary events in ERBB2-amplified GE adenocarcinomas, should be evaluated in clinical trials.

PMID:
25401468
PMCID:
PMC4348950
DOI:
10.1172/JCI75200
[Indexed for MEDLINE]
Free PMC Article

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