Prognostic significance of CD45 antigen expression in pediatric acute lymphoblastic leukemia

The treatment of pediatric acute lymphoblastic leukemias (ALL) has seen remarkable advances recently. However, relapse occurs in approximately 20% of cases which necessitates identifying additional high risk parameters for treatment intensification. The aim of this study is to assess the prognostic significance of CD45 antigen expression in pediatric ALL.

We studied 363 pediatric patients with B cell precursor-ALL (BCP-ALL) (n = 313) and T-ALL (n = 50). The ratio of median fluorescence intensity of CD45 expressed in leukemic blasts and normal lymphocytes was calculated. The 75th percentile was taken as cut-off to categorise patients into CD45 high and CD45 low groups.

The 75th percentile was 0.141 in BCP-ALL and 0.548 in T-ALL. In BCP-ALL, there was a statistically significant association of age (≥10 years) (p = 0.027) and National Cancer Institute high risk group (p = 0.001) with high CD45 expression but not in T-ALL. Worse event-free survival (EFS) was seen with high CD45 expression in BCP-ALL (42.17% versus 60.83%, p = 0.0053). In T-ALL, there was no association between CD45 expression and EFS (CD45 high 40.40% versus low 67.35%, p = 0.414). The overall survival (OS) was 70% versus 60% (p = 0.38) in BCP-ALL and the OS was 82% versus 68% (p = 0.16) in T-ALL for CD45 low versus CD45 high groups, respectively.

We conclude that high CD45 surface expression is associated with worse EFS in pediatric BCP-ALL.