title: Detection and clinical significance of intratumoral EGFR mutational heterogeneity in Chinese patients with advanced non-small cell lung cancer.
abstract: OBJECTIVE
  This study evaluated occurrence and potential clinical significance of intratumoral EGFR mutational heterogeneity in Chinese patients with non-small cell lung cancer (NSCLC).
  
  
  METHODS
  Eighty-five stage IIIa-IV NSCLC patients who had undergone palliative surgical resection were included in this study. Of these, 45 patients carried EGFR mutations (group-M) and 40 patients were wild-type (group-W). Each tumor sample was microdissected to yield 28-34 tumor foci and Intratumoral EGFR mutation were determined using Denaturing High Performance Liquid Chromatography (DHPLC) and Amplification Refractory Mutation System (ARMS). EGFR copy numbers were measured using fluorescence in situ hybridization (FISH).
  
  
  RESULTS
  Microdissection yielded 1,431 tumor foci from EGFR mutant patients (group-M) and 1,238 foci from wild-type patients (group-W). The EGFR mutant frequencies in group-M were 80.6% (1,154/1,431) and 87.1% (1,247/1,431) using DHPLC and ARMS, respectively. A combination of EGFR-mutated and wild-type cells was detected in 32.9% (28/85) of samples by DHPLC and 28.2% (24/85) by ARMS, supporting the occurrence of intratumoral heterogeneity. Thirty-one patients (36.5%) were identified as EGFR FISH-positive. Patients harboring intratumoral mutational heterogeneity possessed lower EGFR copy numbers than those tumors contained mutant cells alone (16.7% vs. 71.0%, P<0.05). Among 26 patients who had received EGFR-TKIs, the mean EGFR mutation content was higher in patients showing partial response (86.1%) or stable disease (48.7%) compared with patients experiencing progressive disease (6.0%) (P = 0.001). There also showed relationship between progression-free survival (PFS) and different content of EGFR mutation groups (pure wild type EGFR, EGFR mutation with heterogeneity and pure mutated EGFR) (P = 0.001).
  
  
  CONCLUSIONS
  Approximately 30% of patients presented intratumoral EGFR mutational heterogeneity, accompanying with relatively low EGFR copy number. EGFR mutant content was correlated with the response and prognosis of EGFR-TKIs.
authors: Key Laboratory of Carcinogenesis and Translational Research Ministry of Education, Department of Thoracic Medical Oncology, Peking University Cancer Hospital & Institute, Beijing, China.
authors: Hua
authors: H
authors: Bai
authors: Zhijie
authors: Z
authors: Wang
authors: Yuyan
authors: Y
authors: Wang
authors: Minglei
authors: M
authors: Zhuo
authors: Qinghua
authors: Q
authors: Zhou
authors: Jianchun
authors: J
authors: Duan
authors: Lu
authors: L
authors: Yang
authors: Meina
authors: M
authors: Wu
authors: Tongtong
authors: T
authors: An
authors: Jun
authors: J
authors: Zhao
authors: Jie
authors: J
authors: Wang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000235:genetics; D014408:Biomarkers, Tumor / Q000235:genetics; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D002681:China; D004252:DNA Mutational Analysis; D018572:Disease-Free Survival; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011379:Prognosis; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor; D047428:Protein Kinase Inhibitors; C512478:EGFR protein, human; D066246:ErbB Receptors