Genomic Profiling of HER2-Positive Gastric Cancer: PI3K/Akt/mTOR Pathway as Predictor of Outcomes in HER2-Positive Advanced Gastric Cancer Treated with Trastuzumab

作者：Asunción Díaz-Serrano, Bárbara Angulo, Carolina Domínguez, Roberto Pazo-Cid, Antonieta Salud, Paula Jiménez‐Fonseca, Ana León, María Galán, María Alsina, Fernando Rivera, Carlos Plaza, Luis Paz‐Ares, Fernando López‐Ríos, Carlos Gómez-Martín · 发表于：The Oncologist · 年份：2018 · DOI：10.1634/theoncologist.2017-0379 · 被引用次数：58 · 研究领域：HER2/EGFR in Cancer Research、Gastric Cancer Management and Outcomes、Advanced Breast Cancer Therapies

BACKGROUND: HER2-positive gastric cancer (GC) affects 7%-34% of patients with GC. Trastuzumab-based first-line treatment has become the standard of care for HER2-positive advanced gastric cancer (AGC). However, there are no clinically validated biomarkers for resistance to HER2-targeted therapies. Upregulation of PI3K pathway and tyrosine kinase receptor (TKR) alterations have been noted as molecular mechanisms of resistance in breast cancer. Our study aimed to perform a molecular characterization of HER2-positive AGC and investigate the role of PI3K/Akt/mTOR signaling pathway activation and TKR gene copy number (GCN) gains as predictive biomarkers in HER2-positive AGC treated with trastuzumab. PATIENTS AND METHODS: Forty-two HER2-positive GC samples from patients treated with trastuzumab-based first-line chemotherapy were selected. DNA samples were sequenced. PTEN and MET immunohistochemistry were also performed. RESULTS: Concurrent genetic alterations were detected in 97.1% of HER2-positive AGC. We found activation of PI3K/Akt/mTOR pathway in 52.4% of patients and TKR GCN gains in 38.1%. TKR GCN gains did not correlate with overall survival (OS) or progression-free survival (PFS). Multivariate Cox models showed that PI3K/Akt/mTOR activation negatively affects the effectiveness of trastuzumab-based chemotherapy in terms of OS and PFS. CONCLUSION: Our results provide for the first time a detailed molecular profile of concurrent genetic alterations in HER2-positive AGC. PI3K p...