ZAP-70 Expression and Stem Cell Transplantation Results in Patients with CLL.

Abstract

The absence of mutations in the VH gene (UM-VH) and the expression of ZAP-70 by leukemic cells are closely related adverse prognostic factors in CLL. Whether ZAP-70 should substitute VH gene analysis as prognostic predictor in patients with CLL is a matter of debate. We and others have shown that allogeneic but not autologous stem-cell transplantation may overcome the negative impact of the UM-VH on the outcome of patients with CLL. Herein we report on transplantation results based on ZAP-70 expression in leukemic cells. Thirty-seven patients (24 M/13 F; median age: 48 years, range: 29-63) received either an autologous (auto-SCT) (n=22) or an allogeneic (allo-SCT) (n=15) transplant. ZAP-70 was assessed by flow cytometry (19 cases), lymph node immunohistochemistry (10 cases) or both (8 cases). No discrepancies were observed in those cases in which both peripheral blood and lymph nodes were analyzed. Thirty-one patients were ZAP-70 positive and 6 ZAP-70 negative. ZAP-70 was positive in all UM-VH (n=24) and in 4 of 8 mutated VH patients. After a median follow-up of 62 months (range: 4 – 142), 5-year survival is 86% (66% to 100%) for allo-SCT and 50% (28% to 72%) for auto-SCT (p=NS), whereas 5-year disease-free survival (DFS) is 80% (54% to 100%) for allo-SCT and 37% (15% to 59%) for auto-SCT (p=0.03). Seventeen patients have relapsed: 16 of 31 of those being ZAP-70 positive and 1 of 6 of those ZAP-70 negative. In ZAP-70 positive patients the cumulative relapse rate at 5 years is 10% (2% to 65%) in the allo-SCT group and 53% (35% to 81%) in the auto-SCT group (p=0.04) (figure 1a). In addition, ZAP-70 positive patients submitted to allo-SCT have a trend for a longer DFS (76% at 5 years; 46% to 100%) than those receiving an auto-SCT (39% at 5 years; 15% to 63%) (p=0.07) (figure 1b). In summary, among transplanted patients those with ZAP-70 positive CLL have a better relapse rate and DFS if submitted to allo-SCT. [Display omitted]