181 Background: Current diagnostic pathways for kidney, bladder and prostate cancers rely on invasive procedures and imaging. Non-invasive MCED requires robust analyte recovery and accurate tumour signal detection. Urine is an attractive alternative to blood, particularly for genitourinary malignancies. This Phase 1/2 study evaluates feasibility and analytical performance of urine-based circulating tumour DNA (ctDNA) and circulating tumour RNA (ctRNA) versus plasma in early-stage prostate, bladder and kidney cancers, validated against healthy and benign controls. Methods: Patients with biopsy-proven localised prostate, bladder and kidney cancer, plus healthy and benign controls, provided paired urine and blood samples. DNA and RNA were extracted from urine and plasma, quantified, and analysed using amplicon-based targeted next-generation sequencing to detect cancer-associated genomic alterations and transcripts. Sensitivity of urine versus plasma ctDNA was analysed by cancer type. Incremental value of urine ctDNA/ctRNA, particularly for prostate cancer, was assessed. Healthy controls were used for test calibration. A preplanned interim analysis was scheduled upon recruitment of the first 30 participants (n=30). Results: All urine samples (15 control, 15 prostate cancer, 14 bladder cancer, 9 kidney cancer) yielded adequate DNA, with highest concentration from bladder cancer cases. One case was excluded from analysis due to poor on-target reads, possibly from undiagnosed concomitant Serratia urinary tract infection. No cancer-associated alterations were detected in controls, confirming strong assay calibration and specificity. Urine ctDNA markedly outperformed plasma ctDNA for bladder cancer detection, identifying cancer-associated alterations in 92.3% of cases compared with 15.4% in blood. Significantly, 7/10 (70%) of bladder cancer cases detected by urine ctDNA alone belonged to EAU high risk groups including 2 cases of muscle-invasive (pT2) disease, yet urine cytology was only positive in 3/10 (30%). In prostate cancer, detection significantly improved from 6.7% with urine ctDNA alone to 40.0% with combined ctDNA/ctRNA analysis, largely driven by prostate-specific transcripts such as TMPRSS2-ERG fusions. Urine ctRNA was detected in 6/9 (66.7%) of ISUP grade group ≥3 cases. Among those detected by urinary ctRNA alone, 80% (4/5) were ISUP grade group ≥3. Urine also demonstrated improved detection over blood for kidney cancer, although overall sensitivity remained modest (14.3%). Conclusions: Urine is a feasible, analytically robust biospecimen for MCED. Urine ctDNA outperforms plasma for bladder cancer detection, while urine ctRNA enhances prostate cancer detection. Absence of false positives in controls supports good calibration and further evaluation of this urine-based assay.
Chen et al. (Tue,) studied this question.