Chronic Lymphocytic Leukemia Prognostic Index: A New Integrated Scoring System to Predict the Time to First Treatment in Chinese Patients with Chronic Lymphocytic Leukemia

Abstract

Background: The established clinical staging systems (Rai/Binet) of chronic lymphocytic leukemia (CLL) cannot accurately predict the appropriate treatment of patients in the earlier stages. In the past two decades, several prognostic factors have been identified to predict the outcome of patients with CLL, but only a few studies investigated more markers together. To predict the time to first treatment (TTFT) in patients of early stages, we evaluated the prognostic role of conventional markers as well as cytogenetic abnormalities and combined them together in a new prognostic scoring system, the CLL prognostic index (CLL-PI). Methods: Taking advantage of a population of 406 untreated Chinese patients with CLL at early and advanced stage of disease, we identified the strongest prognostic markers of TTFT and, subsequently, in a cohort of 173 patients who had complete data for all 3 variables, we integrated the data of traditional staging system, cytogenetic aberrations, and mutational status of immunoglobulin heavy chain variable region (IGHV) in CLL-PI. The median follow-up time was 45 months and the end point was TTFT. Results: The median TTFT was 38 months and the 5-year overall survival was 80%. According to univariate analysis, patients of advanced Rai stages (P < 0.001) or with 11q- (P = 0.002), 17p- (P < 0.001), unmutated IGHV (P < 0.001), negative 13q- (P = 0.007) and elevated lactate dehydrogenase levels (P = 0.001) tended to have a significantly shorter TTFT. And subsequently, based on multivariate Cox regression analysis, three independent factors for TTFT were identified: advanced clinical stage (P = 0.002), 17p- (P = 0.050) and unmutated IGHV (P = 0.049). Applying weighted grading of these independent factors, a CLL-PI was constructed based on regression parameters, which could categorize four different risk groups (low risk [score 0], intermediate low [score 1], intermediate high [score 2] and high risk [score 3-6]) with significantly different TTFT (median TTFT of not reached (NR), 65.0 months, 36.0 months and 19.0 months, respectively, P < 0.001). Conclusions: This study developed a weighted, integrated CLL-PI prognostic system of CLL patients which combines the critical genetic prognostic markers with traditional clinical stage. This novel modified PI system could be used to discriminate among groups and may help predict the TTFT and prognosis of patients with CLL.

Keywords

• 17p Deletion; Chronic Lymphocytic Leukemia; Immunoglobulin Heavy Chain Variable Mutation; Prognostic Index; Time to First Treatment