Use of TP4303 to identify prostate cancer cells in voided urine samples.

Introduction: Prostate cancer is the second most common malignancy in men worldwide. Genomic VPAC receptors are expressed on malignant prostate cancer cells and can be targeted and imaged optically by a peptide labeled fluorophore. The objective of our study was to assess the feasibility of detecting cancer of the prostate using a voided urine sample.

Materials and methods: Patients ≥ 40 years old, with lower urinary tract symptoms and serum PSA > 4 ng/mL formed the study group. The first 50 mL of voided urine sample was collected and processed. The cells that were shed in the voided urine were fixed and stained with a peptide TP4303 and incubated. The slide was then stained with DAPI which binds with the DNA in the nucleus. All patients underwent a standard 12-core TRUS-guided prostate biopsy.

Results: A total of 318 patients were included in the study, of these 158 were histologically confirmed cancers. Voided urine samples were positive for VPAC receptors in 154 (97.46%) of these. The remaining 160 patients had no cancer on the HPR examination and none of these patients were positive for VPAC receptors.

Conclusions: This study validates our belief that patients with prostate cancer shed malignant cells in the urine that can be identified by targeting the VPAC receptors. If these results are further validated by multicentric studies, then this could form the basis for indications for a preliminary prostate biopsy in patients with elevated serum PSA but normal digital examination or in patients needing a repeat biopsy.