Serum thymidine kinase 1 concentration in Chinese patients with chronic lymphocytic leukemia and its correlation with other prognostic factors

Chronic lymphocytic leukemia (CLL) shows a remarkable heterogeneity, with some patients having an almost normal lifespan, others surviving only several months after diagnosis despite intensive therapy. The aim of this study was to investigate the serum thymidine kinase 1 (TK1) concentration in Chinese patients with CLL and its correlation with well-established other prognostic factors. Enhanced chemiluminescent dot blot assay was performed to measure serum TK1 concentration in 80 CLL patients. The concentration of TK1 was significantly increased in patients with Binet C (P = 0.002), higher levels of serum lactate dehydrogenase (LDH) (P = 0.012) and β2-microglobulin (β2-MG) (P = 0.025), unmutated IGHV status (P < 0.001), or higher expression levels of ZAP-70 (P = 0.014) and CD38 (P = 0.018) groups compared to the patients with Binet A, lower levels of serum LDH and β2-MG, mutated IGHV status, or lower expression levels of ZAP-70 and CD38 groups, respectively. Strong correlation of TK1 level with IGHV mutations (r = 0.412, P < 0.001) or ZAP-70 (r = 0.263, P = 0.024) was observed. According to receiver operating characteristic curve analysis for serum TK1 concentration and IGHV mutational status, area under the curve was 0.757 (P = 0.001) and the optimal cut-off value of serum TK1 concentration level was 1.75 pM, with a 87.8% specificity, a 63.6% sensitivity. It was showed that serum TK1 concentration could be a predictive marker of IGHV mutational status, and might be applied for the assessment of prognosis in patients with CLL.