Detection of prostate cancer–specific fusion marker TMPRSS:ERG using droplet digital PCR

Aim: This study aimed to explore a novel method for detecting the prostate cancer-specific fusion marker TMPRSS2:ERG to evaluate cancer risk and aggressiveness at diagnosis. Methods: We used prostate cancer cells from the Vcap sample, positive for TMPRSS2:ERG, as the experimental model. Female urine samples, TMPRSS2:ERG fusion-negative LNCaP cell samples, and clinical samples A203 and A204 served as controls. We established optimal conditions using quantitative PCR and droplet digital PCR (ddPCR). Dilution experiments were conducted with female urine samples. A total of 27 clinical urine samples from prostate cancer patients were retrospectively tested using ddPCR, while a prospective ddPCR experiment was conducted with 21 pathological RNA samples. Results: Dilution experiments indicated that ddPCR had a specificity of 99.9% for detecting prostate cancer fusion markers, achieving a sensitivity level capable of detecting a single fusion-positive cell among 10,000-20,000 cells in urine sediment. In multiplex testing, fusion marker detection rates were 59.3% in urine samples and 19% in pathological samples, with 100% specificity. Eleven cases exhibited multiple fusion subtypes, correlating with heightened cancer risk. Our method identified three patients with the rare subtype III, not previously detected by qPCR. Conclusions: The ddPCR platform provides high specificity and sensitivity for detecting fusion markers in prostate cancer, facilitating early diagnosis and concurrent analysis of rare subtypes.