MCM5 urine expression (ADXBLADDER) is a reliable biomarker of high-risk non- muscle-invasive bladder cancer recurrence: A prospective matched case-control study

BACKGROUND: Mini Chromosome Maintenance 5 (MCM5) is considered as a urinary biomarker of bladder cancer. ADXBLADDER is a commercially available test to detect MCM5 antibodies. OBJECTIVE: External validation of ADXBLADDER test as a urinary biomarker of histopathologically confirmed non-muscle invasive bladder cancer (NMIBC) recurrence. METHODS: The study enrolled 119 consecutive patients with a history of NMIBC and 37 healthy volunteers matched as controls. Single, full-void urine samples were collected from patients before cystoscopy ± TUR. To measure MCM5 expression, Arquer Diagnostics ADXBLADDER test was used. The study protocol was registered within the clinical trials database (NCT03796299). RESULTS: Among patients with NMIBC history, recurrence was diagnosed in 83 patients (69.7%). ADXBLADDER demonstrated sensitivity of 73.5% (95% confidence interval (CI) 62.7%–82.6%), specificity of 33.3% (95% CI 18.6% to 51%), overall negative predictive value (NPV) of 35.3% (95% CI 23.3% to 49.5%) and overall positive predictive value of 71.8% (95% CI 66.1% to 76.8%) for detecting recurrence. In a control group, false positive ADXBLADDER results were noticed in 18 patients (48.6%). The sensitivity and NPV were the highest in invasive tumors (100% and 100%, respectively) and in high-grade recurrences (81.8% and 94.1%, respectively). CONCLUSIONS: ADXBLADDER has a moderate sensitivity and poor specificity in detecting NMIBC recurrence. However, it properly diagnoses patients with T1 + stage recurrence or high-grade tumors.