Circulating levels and clinical significance of soluble GD40 in patients with hematologic malignancies

BACKGROUND. CD40 plays a critical role in immunoregulation, and CD40 ligation is being investigated as a therapy for hematologic malignancies. Although soluble CD40 (sCD40) is a potential modulator of both antitumor responses and CD40-based therapies, the levels and significance of sCD40 in patients with hematologic malignancies are unknown. METHODS. The authors evaluated serum/plasma sCD40 levels using an enzyme-linked immunoassay in patients with acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), and multiple myeloma (MM). RESULTS. Levels of sCD40 were elevated in serum (> 1.697 ng/mL) or plasma (>0.649 ng/mL) from 73% of patients with CLL, 80% of patients with MCL, 40% of patients with AML, 43% of patients with MDS, and 33% of patients with MM. Multivariate analysis of patients with MM demonstrated that elevated sCD40 was a significant, independent predictor of poor survival. In multivariate analysis of patients with AML, sCD40 was a significant prognostic factor when the interaction of age and sCD40 was included as a variable. Further analysis demonstrated that elevated sCD86 levels were associated with significantly shorter survival only in AML patients younger than age 64 years. Release of sCD40 by CLL cells was induced by cross-linking with CD40 monoclonal antibody. CONCLUSIONS. Many patients with hematologic malignancies have elevated circulating levels of sCD40, and these elevated levels are associated with a poor prognosis at least in patients with MM and AML, suggesting that sCD40 may have a role in modulating antitumor responses and also may be a useful prognostic marker. In addition, the findings suggested that further studies will be required to determine the effect of circulating sCD40 on the clinical effectiveness of CD40-ligating reagents used in the treatment of hematologic malignancies.