Epidermal growth factor receptor R521K polymorphism shows favorable outcomes in KRAS wild-type colorectal cancer patients treated with cetuximab-based chemotherapy.
The R521K polymorphism of epidermal growth factor receptor has attenuated affinity in ligand binding and proto-oncogene induction, which may affect the efficacy of cetuximab. We analyzed the effect of this polymorphism on the outcome of 112 patients with KRAS wild-type metastatic colorectal carcinoma treated with first-line cetuximab plus FOLFOX-4. The associations of this polymorphism with vascular endothelial growth factor (VEGF) expression and clinicopathologic characteristics were also examined. The results showed that the frequencies of the G/G, G/A, and A/A genotypes were 32.1% (n = 36), 42.9% (n = 48), and 25.0% (n = 28), respectively. A marked decrease in VEGF expression levels (66.7% vs 28.9%, P < 0.01) was observed in patients with 521A allele variants (Arg/Lys or Lys/Lys), which were associated with a decreased tumor size (55.6% vs 31.6%, P = 0.02), good histological differentiation (63.9% vs 85.5%, P = 0.01), decreased lymphovascular invasion (69.4% vs 39.5%, P < 0.01), and a higher response rate to cetuximab plus FOLFOX treatment (55.6% vs 78.9%, P = 0.01). In addition, this polymorphism was associated with a longer progression-free period (P = 0.001) and overall survival (P = 0.001). By multivariate analysis, this polymorphism was also identified as an independent prognostic factor. These data suggest that the R521K polymorphism of epidermal growth factor receptor, by reducing its activation and a consequential downregulation of its target genes, including VEGF, could be a key determinant of an increased response to cetuximab-based chemotherapy and a longer survival for KRAS wild-type colorectal carcinoma patients.
National Yang-Ming University School of Medicine, Taipei, Taiwan.
Yao-Yu
YY
Hsieh
Cheng-Hwai
CH
Tzeng
Ming-Huang
MH
Chen
Po-Min
PM
Chen
Wei-Shu
WS
Wang
D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002454:Cell Differentiation; D000068818:Cetuximab; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics*; D018572:Disease-Free Survival; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D006801:Humans; D002955:Leucovorin / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009944:Organoplatinum Compounds / Q000627:therapeutic use; D011110:Polymorphism, Genetic; D011379:Prognosis; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics*
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; C117307:KRAS protein, human; C000715470:MAS1 protein, human; D009944:Organoplatinum Compounds; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D066246:ErbB Receptors; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins; D000068818:Cetuximab; D002955:Leucovorin; D005472:Fluorouracil