CD38 Expression in B-Cell Chronic Lymphocytic Leukemia: Association with Clinical Presentation and Laboratory Features in 64 Newly Diagnosed Patients.

Background: B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the progressive accumulation of a neoplastic clone consisting of CD5/CD19/CD23/surface immunoglobulin cells. Despite this homogeneity in phenotype, B-CLL can follow either an indolent or a progressive course. CD38 is a transmembrane glycoprotein expressed on the surface of leukemic cells in a significant percentage of patients with B-CLL. Recent studies suggest that CD38 expression in CLL is a reliable prognostic marker, leading to an unfavorable clinical course with a more advanced stage of disease, poor responsiveness to chemotherapy and a shorter survival rate, along with others markers like ZAP-70 that reflect more accurately the mutagenic status of VH gene region, unfortunately not yet available in clinical practice routinely.

Objectives: To assess the association of CD38+ expression with clinical and laboratory parameters at diagnosis in patients with B-CLL.

Patients and Methods: CD38 expression was analyzed in 64 unselected newly diagnosed B-CLL patients from January 2003 to May 2005 seen at the Hematology Center of Pernambuco-Brazil (HEMOPE). According to Damle et al. patients with 30% or more B cells expressing CD38 were considered positive(CD38+), and those with less than 30% were considered negative(CD38−). Various patient characteristics were studied including age, sex, Binet stage, hemoglobin, ß2 microglobulin and lactate dehydrogenase levels in the serum. Statistical differences between each group (CD38+ vs CD38−) were analyzed using χ² tests for categorical variables and Student’s t-tests for continuous variables.

Results: Thirty-six patients (56.25%) were CD38+ and 28 (43.75%) were CD38-. Their median age at diagnosis was 64 years (range, 39–83) and the male to female ratio was 1.46:1. There were no differences between age, sex, hemoglobin and ß2 microglobulin levels in the CD38+ and CD38- groups. ß2 microglobulin level, however, was not available for assessment in all patients. Lactate dehydrogenase level was significantly higher in the CD38+ group (p=0.007). It was observed a trend toward a higher Binet stage (B or C) in the CD38+ compared with CD38- group (63.4 vs. 36.6% respectively), although not statistically significant (p=0.09) possibly because of the small number of patients studied.

Conclusion: CD38 expression was associated with a higher lactate dehydrogenase level and a tendency for more aggressive clinical stage. CD38 evaluation is a measurable biological parameter that is not as subjective as the evaluation of some clinical parameters and should be considered a stantard clinical test for newly diagnosed B-CLL patients.