CD13 expression is an independent adverse prognostic factor in adults with Philadelphia chromosome negative B cell acute lymphoblastic leukemia.

In adults with precursor-B lymphoblastic leukemia (BCP-ALL) there remain a majority of patients who fall in an intermediate cytogenetics risk category with a heterogenous outcome. We analyzed immunophenotypic and cytogenetic factors retrospectively in 126 consecutive adults with BCR-ABL negative BCP-ALL who were treated with a pediatric-based protocol at a single institution over a 10 year period. In addition to age, WBC and cytogenetic findings, CD13 positivity was an independent poor prognostic indicator for overall survival (OS, p=0.049), event-free survival (EFS, p=0.013), and relapse-free survival (RFS, p<0.001). The prognostic value of CD13 was primarily seen in patients with normal or intermediate risk cytogenetics. A risk model that includes age>60 years, WBC>30×10(9)/L, SWOG high/very high risk cytogenetics and CD13 positivity, performs better than a risk model of cytogenetics alone for stratifying patients by OS (p=0.001), EFS (p=7×10(-4)) and RFS (p=8×10(-4)). Incorporating CD13 into a scoring system provides high discrimination for relapse risk and survival.