title: KRAS p.G13D mutation and codon 12 mutations are not created equal in predicting clinical outcomes of cetuximab in metastatic colorectal cancer: a systematic review and meta-analysis.
abstract: BACKGROUND
  The authors conducted a systematic review and meta-analysis to examine whether patients who had metastatic colorectal cancer (mCRC) with the v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) p.G13D mutation (an amino acid substitution at position 13 in KRAS from a glycine to an aspartic acid) and received cetuximab treatment had better clinical outcomes than patients who had mCRC tumors with KRAS codon 12 mutations.
  
  
  METHODS
  Relevant studies were identified by a search of MEDLINE, EMBASE, the Chinese Biomedical Database, and Wan Fang Digital Journals from inception to October 2011. The primary clinical outcomes included the objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). The pooled relative risk (RR) or hazard ratio (HR) was estimated by using fixed-effects or random-effects models according to heterogeneity between studies.
  
  
  RESULTS
  Ten studies were considered eligible that included 1487 patients with mCRC. Patients who had tumors with the KRAS p.G13D mutation had a significantly higher ORR (10 studies; RR, 1.642; 95% confidence interval [CI], 1.131-2.384), longer PFS (1 study; HR, 0.54; 95% CI, 0.36-0.81), and longer OS (1 study; HR, 0.52; 95% CI, 0.33-0.80) than patients who had tumors with KRAS codon 12 mutations. Compared with patients who had KRAS wild-type tumors, patients with the p.G13D mutation had a significantly lower ORR (9 studies; RR, 0.540; 95% CI, 0.381-0.765) and nonsignificantly shorter PFS (1 study; HR, 0.99; 95% CI, 0.68-1.45) and OS (1 study; HR, 1.01; 95% CI, 0.66-1.54).
  
  
  CONCLUSIONS
  Patients who had mCRC with the KRAS p.G13D mutation appeared to benefit more from cetuximab than patients who had tumors with KRAS codon 12 mutations. However, because of the limited sample sizes in the current meta-analysis, these results should be interpreted with caution.
authors.affiliation: Division of Epidemiology, School of Public Health and Primary Care, the Chinese University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Chen
authors.initials: C
authors.lastname: Mao
authors.forename: Ya-Fang
authors.initials: YF
authors.lastname: Huang
authors.forename: Zu-Yao
authors.initials: ZY
authors.lastname: Yang
authors.forename: Da-Yong
authors.initials: DY
authors.lastname: Zheng
authors.forename: Jin-Zhang
authors.initials: JZ
authors.lastname: Chen
authors.forename: Jin-Ling
authors.initials: JL
authors.lastname: Tang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001224:Aspartic Acid / Q000235:genetics; D000068818:Cetuximab; D003062:Codon; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D018572:Disease-Free Survival; D005260:Female; D005998:Glycine / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D016896:Treatment Outcome; D018631:ras Proteins / Q000235:genetics*
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D003062:Codon; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D001224:Aspartic Acid; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins; D000068818:Cetuximab; D005998:Glycine