title: Monitoring of BCR-ABL levels in chronic myeloid leukemia patients treated with imatinib in the chronic phase - the importance of a major molecular response.
abstract: BACKGROUND
  Real time PCR has become the most common technique to monitor BCR-ABL transcript levels of patients treated with kinase inhibitors. The aim of this study was to evaluate BCR-ABL levels of chronic myeloid leukemia patients treated with imatinib in the chronic phase and correlate the response to therapy and event-free survival.
  
  
  METHODS
  BCR-ABL levels were measured in peripheral blood cell samples using Real time PCR at diagnosis and then every 3 months after starting therapy with imatinib. Major molecular response was defined as a three-log reduction from the standardized baseline value. Major molecular response values were adjusted to international scale using a conversion factor of 1.19. The results are reported as a BCR-ABL/ABL ratio (%).
  
  
  RESULTS
  Hematological, major cytogenetic and complete cytogenetic responses were achieved by 57 (95%), 45 (75%) and 38 (63%) patients, respectively. Twenty-four out of sixty patients achieved a major molecular response (40%) in a median time of 8.5 months. Overall survival and event free survival were higher for patients with (100%) versus patients without (77%) a complete cytogenetic response (p-value = 0.01) at 48 months. Patients with complete cytogenetic response and major molecular response had a higher event free survival compared to patients with complete cytogenetic response but without major molecular response (p-value = 0.007).
  
  
  CONCLUSIONS
  In conclusion, the prognostic impact of achieving complete cytogenetic response and a major molecular response and also the importance of molecular monitoring in the follow-up of chronic myeloid leukemia patients were demonstrated.s.
authors.affiliation: Medical Clinic, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil.
authors.forename: Melissa Pereira
authors.initials: MP
authors.lastname: Machado
authors.forename: Juarez Pires
authors.initials: JP
authors.lastname: Tomaz
authors.forename: Irene
authors.initials: I
authors.lastname: Lorand-Metze
authors.forename: Cármino Antonio
authors.initials: CA
authors.lastname: de Souza
authors.forename: Afonso Celso
authors.initials: AC
authors.lastname: Vigorito
authors.forename: Marcia Torresan
authors.initials: MT
authors.lastname: Delamain
authors.forename: Israel
authors.initials: I
authors.lastname: Bendit
authors.forename: Noemi Farah
authors.initials: NF
authors.lastname: Pereira
authors.forename: Katia Borgia Barbosa
authors.initials: KB
authors.lastname: Pagnano