title: Aberrant expression of CD13 identifies a subgroup of standard-risk adult acute lymphoblastic leukemia with inferior survival.
abstract: BACKGROUND
  The standard-risk (SR) subgroup of acute lymphoblastic leukemia in adults (aALL) is a heterogeneous category, with a 20% to 40% relapse rate and a wide range of relapse-free survival (RFS) and overall survival (OS). There is a need to identify at the outset those patients with SR-aALL who are likely to have shorter RFS and OS, so they can be treated more aggressively.
  
  
  METHODS
  Flow cytometric data of 81 patients with SR-aALL treated with a standardized protocol were retrospectively analyzed. Thirty-two patients (40%) relapsed; the median RFS and OS were 12.5 months (range, 1-136 months) and 30 months (range, 3-235 months), respectively. Twenty-six patients survived ≥ 48 months.
  
  
  RESULTS
  Expression of myeloid antigen CD13, using the conventional ≥ 20% threshold and a lower ≥ 5% threshold, was seen in 17 (29%) of 59 and 29 (49%) of 59 patients, respectively, whereas dual expression of CD13 and CD33 was seen in 8 patients. CD13 positivity at ≥ 20% and ≥ 5% threshold was associated with a shorter RFS (P = .0158 and P < .0001, respectively) and OS (P = .0072 and P < .0001, respectively). Dual expression of CD13 (at ≥ 5% or ≥ 20% threshold) and CD33 was associated with inferior OS (P = .0038 and P = .0032, respectively) and RFS (P = .0705 and P = .2516, respectively). For ≥ 20% and ≥ 5% threshold of positivity, 16 of 42 and 28 of 42 who survived < 48 months were positive, compared with 1 of 17 and 1 of 17 who survived ≥ 48 months (P = .0133 and P < .0001, respectively).
  
  
  CONCLUSIONS
  Aberrant expression of CD13 in ≥ 5% of blasts of patients with SR-aALL is an adverse prognostic factor, delineating a subgroup of patients with SR-aALL that should be considered for more aggressive treatment.
authors.affiliation: Division of Laboratory Hematology, Vancouver General Hospital, Vancouver, BC, Canada. Electronic address: bakul.dalal@vch.ca.
authors.forename: Bakul I
authors.initials: BI
authors.lastname: Dalal
authors.affiliation: Division of Laboratory Hematology, Vancouver General Hospital, Vancouver, BC, Canada.
authors.forename: Areej
authors.initials: A
authors.lastname: Al Mugairi
authors.affiliation: Division of Laboratory Hematology, Vancouver General Hospital, Vancouver, BC, Canada.
authors.forename: Steven
authors.initials: S
authors.lastname: Pi
authors.affiliation: Division of Laboratory Hematology, Vancouver General Hospital, Vancouver, BC, Canada.
authors.forename: Soo Yeon
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Division of Laboratory Hematology, Vancouver General Hospital, Vancouver, BC, Canada.
authors.forename: Nikisha S
authors.initials: NS
authors.lastname: Khare
authors.affiliation: Division of Laboratory Hematology, Vancouver General Hospital, Vancouver, BC, Canada.
authors.forename: Jason
authors.initials: J
authors.lastname: Pal
authors.affiliation: Leukemia/Bone Marrow Transplant Program of British Columbia, BC Cancer Agency and University of British Columbia, Vancouver, BC, Canada.
authors.forename: Adam
authors.initials: A
authors.lastname: Bryant
authors.affiliation: Division of Laboratory Hematology, Vancouver General Hospital, Vancouver, BC, Canada.
authors.forename: Alok P
authors.initials: AP
authors.lastname: Vakil
authors.affiliation: Leukemia/Bone Marrow Transplant Program of British Columbia, BC Cancer Agency and University of British Columbia, Vancouver, BC, Canada.
authors.forename: Sally
authors.initials: S
authors.lastname: Lau
authors.affiliation: Leukemia/Bone Marrow Transplant Program of British Columbia, BC Cancer Agency and University of British Columbia, Vancouver, BC, Canada.
authors.forename: Yasser R
authors.initials: YR
authors.lastname: Abou Mourad
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D015415:Biomarkers / Q000378:metabolism; D018826:CD13 Antigens / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006801:Humans; D016130:Immunophenotyping; D008297:Male; D008875:Middle Aged; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000401:mortality*; D011379:Prognosis; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D015415:Biomarkers; D018826:CD13 Antigens
keywords: Flow cytometry; Immunophenotyping; Prognosis; Risk-stratification