Doubling time of soluble CD23: a powerful prognostic factor for newly diagnosed and untreated stage A chronic lymphocytic leukemia patients.

Soluble CD23 (sCD23) levels correlate with the stage, prognosis and overall survival (OS) of patients with chronic lymphocytic leukemia (CLL). Therefore, we prospectively evaluated sCD23 doubling time (sCD23DT) as a prognostic factor for time to treatment (TTT) and OS in 56 newly diagnosed and untreated CLL patients at Binet stage A, and compared it to the most commonly used biological prognostic factors: lymphocyte doubling time, immunoglobulin variable heavy chain (IgVH) mutational status and zeta-associated protein-70 (ZAP-70), CD38, and lipoprotein lipase (LPL) expression. In patients with sCD23DT <1 year, the median TTT and OS were 20 and 83 months compared to 141 and 177 months in patients with sCD23DT >1 year (P<0.0001). Among patients with poor prognostic factors (ZAP-70+, LPL+ and CD38+), an sCD23DT <1 year identified a subpopulation with a shorter TTT. Patients with unmutated IgVH and an sCD23DT <1 year had a median TTT and OS of 14 and 83 months, respectively, whereas these values were 70 and >177 months when sCD23DT was >1 year (P<0.0001 and P=0.0219, respectively). Finally, in a Cox multivariate analysis, sCD23DT was the sole independent prognostic factor for TTT (P=0.0027). Furthermore, sCD23DT refines the prognosis given by other classical prognostic factors. These observations support the introduction of sCD23 evaluation into the routine assessment of CLL patients.