title: Decrease in JAK2 V617F allele burden is not a prerequisite to clinical response in patients with polycythemia vera.
abstract: BACKGROUND
  Although reduction in the JAK2(V617F) allele burden (%V617F) has been suggested as a criterion for defining disease response to cytoreductive therapy in polycythemia vera, its value as a response monitor is unclear. The purpose of this study is to determine whether a reduction in %V617F in polycythemia vera is a prerequisite to achieving hematologic remission in response to cytoreductive therapy.
  
  
  METHODS
  We compared the clinical and hematologic responses to change in %V617F (molecular response) in 73 patients with polycythemia vera treated with either interferon (rIFNα-2b: 28, Peg-rIFNα-2a: 18) or non-interferon drugs (n=27), which included hydroxyurea (n=8), imatinib (n=12), dasatinib (n=5), busulfan (n=1), and radioactive phosphorus (n=1). Hematologic response evaluation employed Polycythemia Vera Study Group criteria, and molecular response evaluation, European Leukemia Net criteria.
  
  
  RESULTS
  Of the 46 treated with interferon, 41 (89.1%) had a hematologic response, whereas only 7 (15.2%) had a partial molecular response. Of the 27 who received non-interferon treatments, 16 (59.3%) had a hematologic response, but only 2 (7.4%) had a molecular response. Median duration of follow up was 2.8 years. Statistical agreement between hematologic response and molecular response was poor in all treatment groups.
  
  
  CONCLUSIONS
  Generally, hematologic response was not accompanied by molecular response. Therefore, a quantitative change in %V617F is not required for clinical response in patients with polycythemia vera.
authors.affiliation: Weill Cornell Medical College, Department of Medicine, Division of Hematology and Medical Oncology, New York, NY 10021, USA.
authors.forename: Emil
authors.initials: E
authors.lastname: Kuriakose
authors.forename: Katherine
authors.initials: K
authors.lastname: Vandris
authors.forename: Y Lynn
authors.initials: YL
authors.lastname: Wang
authors.forename: William
authors.initials: W
authors.lastname: Chow
authors.forename: Amy V
authors.initials: AV
authors.lastname: Jones
authors.forename: Paul
authors.initials: P
authors.lastname: Christos
authors.forename: Nicholas C P
authors.initials: NC
authors.lastname: Cross
authors.forename: Richard T
authors.initials: RT
authors.lastname: Silver
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D005500:Follow-Up Studies; D006801:Humans; D016898:Interferon-alpha / Q000627:therapeutic use; D053614:Janus Kinase 2 / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation; D011087:Polycythemia Vera / Q000188:drug therapy* / Q000235:genetics*; D012074:Remission Induction; D016896:Treatment Outcome
chemical_list: D016898:Interferon-alpha; D053614:Janus Kinase 2
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