Clinico-prognostic implications of simultaneous increased serum levels of soluble CD23 and beta2-microglobulin in B-cell chronic lymphocytic leukemia

Abstract

Soluble CD23 (sCD23) and beta-2 microglobulin (beta2-m) are reliable prognostic parameters in B-cell chronic lymphocytic leukemia (CLL); however, their merit over well-established clinical variables such as clinical stages, bone marrow (BM) histology and lymphocyte doubling time (LDT) remains to be defined. Furthermore, information dealing with the impact on overall survival of the simultaneous increase of either beta2-m or sCD23 are lacking. In this prospective study based on 106 B-cell CLL patients, we propose a combination of beta2-m and sCD23 as a strong prognostic system whose statistical significance was mainly due to an excess of deaths in the subgroup displaying increased serum levels of either beta2-m or sCD23. Multivariate survival analysis confirmed the important dominant role of such a finding, thus excluding features with a high degree of codependence (i.e. clinical stages, LDT) and including variables with low association (i.e. BM histology) in the final regression model. The presence of increased serum levels of beta2-m/sCD23 and diffuse BM histology signified high-risk disease, whereas the absence of any adverse variable was associated with prolonged survival; in between there was a subgroup with only 1 characteristic which displayed an intermediate pattern of survival. Finally, on the basis combined increased serum levels of beta2-m and sCD23, a better stratification of low- and intermediate-risk patients could be obtained, thus allowing the formulation of a clinico-biological staging for CLL.