XPA-210: a new proliferation marker determines locally advanced prostate cancer and is a predictor of biochemical recurrence Stefan AufderklammJorg HennenlotterTilman TodenhoeferGeorgios GakisDavid Schilling • Ulrich VogelUrsula KuehsJohannes DlugoschJudith KnappAxel MerseburgerValentina Gerber • Anna OrdelheideJoachim HevlerArnulf StenzlChristian Schwentner

Purpose XPA-210 is a proliferation marker derived from Thymidine kinase-1. It is of clinical significance in kidney, breast, and bladder cancer. There are no data available for XPA-210 in prostate cancer (PC). Herein, we aim to determine the clinical usefulness of XPA-210 in PC. Materials and methods In a retrospective study, cancer and benign tissue samples of 103 patients (median age 65 years, median PSA 9.04 ng/ml, median Gleason score 6) who underwent prostatectomy were constructed to a tissue micro array and stained for XPA-210. Semi-quantitative results were correlated with pathological and clinical data by Wilcoxon‐Kruskall‐Wallis and linear regression analysis. Expression levels in PC were correlated between the time of biochemical recurrence and the time to development of metastasis by the Kaplan‐Meier method. Multivariate analysis was done to correlate those with the resection status. Results Mean staining score was 0.51‐0.14 for tumor and benign tissue (P \ 0.0001). Tumor staining score was significantly associated with Gleason score \6/C6 (P \ 0.0001) and T2/T [ 2( P = 0.0007). When dividing the tumor score by the mean value, higher expression of XPA-210 was associated with a shorter time to biochemical recurrence (P = 0.003) and time to development of metastasis (P = 0.0061). Tumor staining (P = 0.0371) was an independent prognostic factor for biochemical relapse regardless of resection status. Conclusions XPA-210 is a new tissue-based prognostic marker for prostate cancer histopathology. It reliably differentiates tumor and normal prostatic tissue predicting biochemical relapse and onset of metastatic disease. XPA210 might be clinically useful for individual decisionmaking in PC-treatment.