title: Exemestane versus anastrozole as front-line endocrine therapy in postmenopausal patients with hormone receptor-positive, advanced breast cancer: final results from the Spanish Breast Cancer Group 2001-03 phase 2 randomized trial.
abstract: BACKGROUND
  Several aromatase inhibitor studies have reported variations in the inhibitory potency of these agents that could lead to differences in clinical outcomes. In the current study, the authors formally evaluated the activity of anastrozole and exemestane in postmenopausal women with hormone-responsive, advanced breast cancer.
  
  
  METHODS
  Postmenopausal women who had measurable disease according to Response Evaluation Criteria in Solid Tumors and had not received previous endocrine therapy for advanced breast cancer were randomized to receive either oral exemestane 25 mg daily or oral anastrozole 1 mg daily until they had disease progression. The primary endpoint was the objective response rate (ORR), and secondary endpoints included the clinical benefit rate (CBR), time to progression (TTP), overall survival, and safety. Crossover to the other aromatase inhibitor was permitted at the time of disease progression; ORR, CBR, and TTP after second-line treatment also were explored.
  
  
  RESULTS
  In total, 103 patients were enrolled. The median patient age was 71.6 years, 52.4% of patients had visceral disease, and 75.8% of patients had ≥ 2 disease sites. Half of the patients had received previous tamoxifen, and 60% had received previous chemotherapy. The efficacy observed in the exemestane and anastrozole groups was an ORR of 36.2% and 46%, respectively; a CBR of 59.6% and 68%, respectively, and a TTP of 6.1 months and 12.1 months, respectively. At progression, 28 patients crossed over to the other aromatase inhibitor, including 16 patients who switched to exemestane (CBR, 43.7%; TTP, 4.4 months) and 12 patients who switched to anastrozole (CBR, 8.3%; TTP, 2 months). Both drugs were generally well tolerated, and no study drug-related serious adverse events were reported.
  
  
  CONCLUSIONS
  In this phase 2 randomized trial, no significant differences in clinical activity were observed in favor of exemestane to justify a superiority phase 3 trial design in the first-line setting.
authors: Medical Oncology Service, Biomedical Research Institute, Arnau de Vilanova University Hospital, Lleida, Spain. allombart@arnau.scs.es
authors: Antonio
authors: A
authors: Llombart-Cussac
authors: Amparo
authors: A
authors: Ruiz
authors: Antonio
authors: A
authors: Antón
authors: Agustí
authors: A
authors: Barnadas
authors: Silvia
authors: S
authors: Antolín
authors: José E
authors: JE
authors: Alés-Martínez
authors: Isabel
authors: I
authors: Alvarez
authors: Raquel
authors: R
authors: Andrés
authors: José A
authors: JA
authors: García Saenz
authors: Juan
authors: J
authors: Lao
authors: Eva
authors: E
authors: Carrasco
authors: Carmen
authors: C
authors: Cámara
authors: Isabel
authors: I
authors: Casas
authors: Miguel
authors: M
authors: Martín
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000077384:Anastrozole; D000730:Androstadienes / Q000009:adverse effects / Q000627:therapeutic use*; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D047072:Aromatase Inhibitors / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000401:mortality; D018592:Cross-Over Studies; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008875:Middle Aged; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy*; D009570:Nitriles / Q000009:adverse effects / Q000627:therapeutic use*; D017698:Postmenopause; D016896:Treatment Outcome; D014230:Triazoles / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000730:Androstadienes; D018931:Antineoplastic Agents, Hormonal; D047072:Aromatase Inhibitors; D009570:Nitriles; D014230:Triazoles; D000077384:Anastrozole; C056516:exemestane