PITX2 DNA Methylation as Biomarker for Individualized Risk Assessment of Prostate Cancer in Core Biopsies

Hypermethylation of the paired-like homeodomain transcription factor 2 (PITX2) gene is a strong predictor of the risk of biochemical recurrence in patients with prostate cancer (PCa) after radical prostatectomy. We investigate whether PITX2 methylation is feasible for individualized risk assessment in prostate core biopsies before surgery. A quantitative, methylation-specific real-time PCR was used to measure PITX2 in three cohorts: i) matched samples of neoplastic and nonneoplastic tissue from 24 patients with PCa, ii) a well-characterized cohort of 300 patients with PCa after radical prostatectomy, and iii) core biopsy specimens from 32 patients with PCa and 31 patients with benign prostatic disease. PITX2 methylation discriminated between neoplastic and nonneoplastic tissue in patients with PCa (P < 0.001). In the second cohort, PITX2 methylation significantly correlated with clinicopathologic parameters, and PITX2 hypermethylation predicted an increased risk of biochemical recurrence in univariate Cox proportional hazards regression analysis (hazard ratio, 1.77; P = 0.046) and Kaplan - Meier analysis (P = 0.043). In 753 prostate biopsies, 720 (95.6%) were applicable for analysis, rendering the assay feasible for diagnostic biopsies. PITX2 methylation was furthermore significantly increased in tumor-positive biopsies and strongly correlated with International Society of Urological Pathology (ISUP) grade groups. This study indicates that the PITX2 methylation assay is feasible in prostate biopsies and might add valuable prognostic information for risk assessment in a presurgical diagnostic setting.