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MO05 - Prognostic and Predictive Biomarkers II (ID 95)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Medical Oncology
- Presentations: 1
MO05.02 - Overexpression of FGFR1 mRNA and protein are more frequent than FGFR1 gene amplification in non-small cell lung cancer (NSCLC) patients (ID 2459)
16:15 - 17:45 | Author(s): S. Singh
Somatic mutations and gene fusions have been identified as oncogenic drivers in lung cancer, however, a number of lung cancers have no apparent molecular aberration driving oncogenesis. It appears that gene/protein overexpression may sustain these “pan-negative” cancers. Fibroblast growth factors (FGFs) and their receptors (FGFRs) regulate cell proliferation, differentiation, migration and survival and dysregulation of this signaling pathway is observed in a proportion of lung cancers. A number of compounds targeting FGF/FGFR are in clinical development but clinically applicable biomarker assays and companion diagnostics that accurately identify patients with tumors sensitive to these agents are needed. We previously presented cell line data demonstrating that FGFR1 mRNA (ME) or protein expression (PE) better identified FGFR1 inhibitor sensitive tumors compared to gene copy number (GCN). The goal of this study was to examine FGFR1 ME, PE and GCN in a surgically treated NSCLC clinical cohort and explore possible associations with clinical features and prognosis.
Immunohistochemistry, brightfield in situ hybridization, and silver in situ hybridization were used to investigate ME, PE and GCN, respectively, in a cohort of 189 NSCLC surgically-treated patients. PE was scored by the H-score method (0-300) and ME on a semiquantative integer scale (0-4+), both evaluating the entire tumor specimen. GCN was scored on continuous scale by counting the individual signals in 50 cells and determining the average GCN per tumor cell.
Amplification (GCN >=4) was present in 8% of the entire cohort and in 11% of the squamous cell carcinoma (SCC) or mixed histology subgroup. No amplifications were found in the adenocarcinomas (ADC) or tumors from never smokers. In contrast, 29% of SCC and ADC patients had high ME (= 4+). Elevated PE (>= 100) was observed in 20% of the cohort, with the highest expression observed in SCC/mixed histology, but 6% of ADCs also showed elevated PE. There was no elevated FGFR1 PE in the never smokers. There was significant correlation but incomplete overlap between biomarkers. There were no prognostic associations, either with overall or disease-free survival, for FGFR1 GCN, ME, or PE. There was excellent inter-observer agreement among the readers of all 3 biomarker assays.
Overexpression of FGFR1 mRNA and protein are more frequent than FGFR1 gene amplification in NSCLC patients. Although GCN amplification was restricted to SCC, elevated ME and PE were found in both ADC and SCC. There was no prognostic association with FGFR1 GCN, ME, or PE. These data are consistent with our previous cell line data that showed elevated PE and ME in non-amplified cells and suggests that GCN may not identify all the potential patients who could benefit from FGF/FGFR pathway inhibitors.
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