title: CD34 expression is associated with poor survival in pediatric T-cell acute lymphoblastic leukemia.
abstract: BACKGROUND
  Children with T-lineage acute lymphoblastic leukemia (T-ALL) have an inferior outcome with combination chemotherapy compared to B-lineage ALL, and still about 30% of the patients relapse within the first 2 years following diagnosis. As CD34 has been related with poor outcome in ALL in general, we investigated the prognostic significance of the stem cell marker CD34, as well as the association of CD34 positivity with the expression of several multidrug resistance (MDR) genes.
  
  
  METHODS
  In this retrospective study, we investigated the prognostic significance of the expression of the early T-cell differentiation marker CD34 and the expression of MDR genes in relation to outcome in a cohort of 72 newly diagnosed pediatric T-ALL patients.
  
  
  RESULTS
  CD34 expression was related to a poor 5-year disease-free-survival and a poor 5-year overall survival. Using the Cox proportional hazard model, CD34 expression predicted for increased risk for relapse and death. Expression of CD34 was associated with elevated MDR1 and MRP1 mRNA expression levels. For the entire T-ALL cohort, these expression levels of MDR1 or MRP1 did not independently predict for poor outcome.
  
  
  CONCLUSIONS
  We conclude that CD34-positive T-ALL has a relatively poor survival that is not explained by the mRNA expression levels of MDR1, LRP, or MRP1.
authors.affiliation: Department of Pediatric Oncology/Hematology, Erasmus University Medical Center-Sophia Children's Hospital, Rotterdam, The Netherlands.
authors.forename: Martine
authors.initials: M
authors.lastname: van Grotel
authors.forename: Marry M
authors.initials: MM
authors.lastname: van den Heuvel-Eibrink
authors.forename: Elisabeth R
authors.initials: ER
authors.lastname: van Wering
authors.forename: Max M
authors.initials: MM
authors.lastname: van Noesel
authors.forename: Willem A
authors.initials: WA
authors.lastname: Kamps
authors.forename: Anjo J P
authors.initials: AJ
authors.lastname: Veerman
authors.forename: Rob
authors.initials: R
authors.lastname: Pieters
authors.forename: Jules P P
authors.initials: JP
authors.lastname: Meijerink
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D018952:Antigens, CD34 / Q000378:metabolism*; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D008297:Male; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism; D054218:Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism* / Q000401:mortality* / Q000473:pathology; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015996:Survival Rate; D020394:Vault Ribonucleoprotein Particles / Q000235:genetics / Q000378:metabolism; D000099187:Major Vault Protein
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018952:Antigens, CD34; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D020394:Vault Ribonucleoprotein Particles; D000099187:Major Vault Protein; C513055:ABCB1 protein, human; C421109:multidrug resistance-associated protein 1