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. Patients and 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 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 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. © 2014 Elsevier Inc. All rights reserved.