title: Evaluation of EGFR protein expression by immunohistochemistry using H-score and the magnification rule: re-analysis of the SATURN study.
abstract: BACKGROUND
  The phase III SATURN study demonstrated that first-line maintenance erlotinib extended progression-free survival (PFS) and overall survival (OS) versus placebo in patients with advanced non-small cell lung cancer (NSCLC). Analysis of epidermal growth factor receptor (EGFR) expression by immunohistochemistry (IHC) found no significant interaction between EGFR IHC status and PFS (p = 0.63) or OS (p = 0.52). The FLEX study of first-line cetuximab plus chemotherapy demonstrated that EGFR IHC expression was predictive of improved OS with cetuximab when assessed by H-score with a magnification rule. This novel method was used to reassess samples from SATURN.
  
  
  METHODS
  The H-score method assigned a score of 0-300 to each patient, based on the percentage of cells stained at different intensities viewed at various magnifications. The discriminatory threshold was set at 200, per the FLEX study, and existing samples were re-read and classed as low (H-score < 200) or high (≥200) EGFR expression. PFS and OS were re-analyzed based on these new classifications.
  
  
  RESULTS
  In the overall and EGFR wild-type populations, erlotinib provided a consistent survival benefit versus placebo. Hazard ratios (HRs) in the overall population were similar between EGFR IHC-positive and -negative patients for median PFS (HR 0.68 [95% confidence interval (CI) 0.53-0.86] and 0.76 [95% CI 0.62-0.93], respectively) and OS (HR 0.80 [95% CI 0.62-1.05] and 0.80 [95% CI 0.64-1.01] for IHC-positive and IHC-negative, respectively). In the EGFR wild-type population, HRs were again similar between EGFR IHC-positive and -negative subpopulations for PFS (HR 0.69 [95% CI 0.51-0.95] and 0.84 [95% CI 0.63-1.12], respectively) and OS (HR 0.78 [95% CI 0.55-1.10] and 0.76 [95% CI 0.55-1.05], respectively).
  
  
  CONCLUSIONS
  These data suggest that EGFR IHC does not have value as a marker to predict erlotinib benefit in the first-line maintenance setting for advanced NSCLC.
authors: Service de Pneumologie, Hôpital Larrey, Centre Hospitalier Universitaire de Toulouse, Université de Toulouse III (Paul Sabatier), Toulouse 31059, France. Electronic address: mazieres.j@chu-toulouse.fr.
authors: Julien
authors: J
authors: Mazières
authors: Wolfram
authors: W
authors: Brugger
authors: Federico
authors: F
authors: Cappuzzo
authors: Peter
authors: P
authors: Middel
authors: Alice
authors: A
authors: Frosch
authors: Ilze
authors: I
authors: Bara
authors: Gaelle
authors: G
authors: Klingelschmitt
authors: Barbara
authors: B
authors: Klughammer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D012307:Risk Factors
chemical_list: D047428:Protein Kinase Inhibitors; D066246:ErbB Receptors
keywords: Biomarkers; Epidermal growth factor receptor; Erlotinib; Immunohistochemistry; Maintenance; Non-small cell lung cancer