LAUSR

This study aimed to assess whether T‐lymphokine‐activated killer cell‐originated protein kinase (TOPK) can be a potent novel biomarker to predict the outcome in patients with primary central nervous system lymphoma (PCNSL). This study enrolled 20 patients who were histologically diagnosed as having diffuse large B‐cell type PCNSL between 2005 and 2015. Using surgical specimens, the expression of TOPK and phosphorylated TOPK (p‐TOPK) was analyzed on immunohistochemistry. Clinical features such as age, sex, Karnofsky performance status (KPS), ocular involvement, deep brain structure involvement, the number of lesions, chemotherapy and radiation therapy were also collected. Impacts of TOPK/p‐TOPK expression on their progression‐free survival (PFS) and overall survival (OS) were examined with multivariate analysis. Median PFS/OS were 24.2 and 39.0 months, respectively. On immunostaining, the mean percentage of TOPK‐positive cells was 35.5 ± 20.8%, and the mean number of p‐TOPK‐positive cells was 13.7 ± 15.7 cells/mm2. The higher expression of p‐TOPK was significantly related to multiple lesions (P = 0.003). Multivariate analysis demonstrated that only the higher expression of p‐TOPK was an independent predictor to shorten both PFS (P = 0.029; hazard ratio (HR), 5.5; 95% confidential interval (CI), 1.2–25.3) and OS (P = 0.014; HR, 7.7; 95% CI, 1.5–41.3). These findings strongly suggest that p‐TOPK may be a potent biomarker to determine the outcome of patients with PCNSL and to develop novel drugs to treat PCNSL.