Impact of epidermal growth factor receptor (EGFR) kinase mutations, EGFR gene amplifications, and KRAS mutations on survival of pancreatic adenocarcinoma

Abstract

Erlotinib, in combination with gemcitabine, has shown clinical benefits in pancreatic adenocarcinoma patients. The presence of EGFR mutations and increased EGFR copy numbers in pancreatic adenocarcinoma was explored. Sixty-six pancreatic cancer patients were included in the analysis. The EGFR mutation was analyzed by DNA sequencing of exons 18-21 in the tyrosine kinase domain. KRAS mutation was analyzed by sequencing codons 12, 13, and 61. Quantitative real-time polymerase chain reaction was performed to analyze the copy number of EGFR. In the current study the EGFR mutation was harbored in only 1 (1.5%) of the 66 inoperable or metastatic pancreatic adenocarcinoma patients. Amino acid substitution was detected in exon 20 of the EGFR gene. Increased EGFR copy numbers (> or =3.0 per cell) were detected in 26 (41%) patients. There was only 1 patient, who had a highly increased EGFR copy number (> or =6.0 per cell), who died, 2.1 months from the date of diagnosis. The EGFR amplification did not significantly influence survival in pancreatic adenocarcinoma patients (P = .935). Thirty-two (49%) of the 65 pancreatic adenocarcinomas examined harbored a point mutation in codons 12 (n = 31) and 61 (n = 1) of the KRAS gene. The presence of a point mutation in codon 12 adversely influenced survival of pancreatic cancer patients (P = .030). The incidence of somatic mutations in the tyrosine kinase domains of EGFR was very low and the increased gene copy number of EGFR did not significantly influence survival.