Clinical Significance of Prolymphocytes in Chinese Patients with Chronic Lymphocytic Leukemia Including Those Treated with BTK Inhibitors

Background A higher percentage of prolymphocytes was reported to be associated with worse survival outcomes in patients with chronic lymphocytic leukemia (CLL). Therefore, we tried to explore the effect of prolymphocytes on the prognosis of CLL in a cohort of Chinese patients. Methods Three hundred untreated CLL patients were enrolled. The relevance of prolymphocyte percentage with other parameters was analyzed. Then an optimal cutoff of prolymphocyte percentage was provided by X-tile analysis. Further survival analysis and prognostic model construction were used to validate the predictive value of prolymphocyte percentage. Results Patients with a higher prolymphocyte percentage were more likely to present with advanced stages, higher β2-microglobulin, unmutated immunoglobulin heavy-chain variable region gene(IGHV), and tumor protein 53 gene(TP53) aberration. The optimal cutoff of the percentage of prolymphocytes was 1%. Prolymphocyte percentage showed a marginally independent prognostic effect on treatment free survival (TFS)(P = 0.071) and did not independently predict overall survival (OS) (P = 0.913) in multivariate analysis. Nomograms combining factors of CLL international prognostic index(CLL-IPI) and prolymphocyte percentage showed better discrimination and calibration in contrast with CLL-IPI alone. Besides, patients with a higher prolymphocyte percentage were more likely to progress or relapse after treatment with Bruton tyrosine kinase inhibitors(BTKi) (P = 0.038). Conclusions Prolymphocyte percentage was associated with various clinical and biological parameters as well as prognosis of treatment naïve CLL patients.