Insulin-like growth factor receptor-1 (IGF1R) and epidermal growth factor receptor (EGFR) amplification and expression in surgically resected NSCLC.

Abstract

10519 Background: IGF1R represents a novel molecular target in non-small cell lung cancer (NSCLC). IGF1R and EGFR activation is essential to mediate tumor cell survival, proliferation and invasion. This study investigates the prognostic role of IGF1R and EGFR copy number gain (CNG) by fluorescence in situ hybridization (FISH) and protein overexpression by immunohistochemistry (IHC) in surgically resected NSCLC. Methods: 114 NSCLC patients were evaluated; median age was 66y (range 40–84), Male/Female:96/18; squamous (SCC)/adeno/BAC/other:59/34/9/12; smoker/never smoker:105/9, and stage I/II/III:71/18/25. IGF1R and EGFR FISH were tested by customized and commercial probes, respectively; positive specimens showed gene amplification or polysomy (≥4 copies in ≥10% of tumor cells). IGF1R and EGFR protein expression were evaluated using mouse antibodies (clones 24-31 and 3147, respectively); overexpression was defined by ≥10% positive cells. Kaplan-Meier estimates of survival and time to recurrence were calculated for clinical and biologic variables using Cox model for multivariate analysis. Results: 46 tumors (40%) were IGF1R FISH+ and 76 (77%) were EGFR FISH+. IGF1R FISH+ was associated with EGFR FISH+ (p=0.03) and co-amplification was observed in 34 cases (30%). IGF1R and EGFR FISH+ were associated with SCC (p=0.01 and p=0.05, respectively). IGF1R and EGFR overexpression was detected in 36% and 55% of NSCLC patients and co-expression was detected in 25%. Co-amplification and co-expression of both receptors were significantly associated (p=0.045). IGF1R and EGFR co-amplification and co-expression associated with shorter disease free survival (DFS; p=0.05, p=0.05 respectively), also at multivariate analysis adjusting for stage (p=0.0002). Conclusions: IGF1R and EGFR are frequently co-amplified in NSCLC and CNG correlates with protein overexpression. Both co-amplification and co-expression of IGF1R and EGFR predicts shorter DFS. These results provide a strong rational for targeting simultaneously EGFR and IGF1R in clinical trials for NSCLC. We thank the Italian Association for Cancer Research (AIRC) for supporting the study (AF Fellowship).