Adding Mitomycin to BCG as Adjuvant Intravesical Therapy for High-risk Non-Muscle-invasive Bladder Cancer

PROTOCOL SYNOPSIS Background: Instillation of Bacillus of Calmette-Guerin (BCG) into the urinary bladder (intravesical administration) improves rates of disease recurrence and progression after transurethral resection (TUR) of high risk, non-muscle-invasive bladder cancer (NMIBC), but over 30% of people still develop recurrent transitional cell carcinoma (TCC) despite optimal therapy with adjuvant intravesical BCG. Our meta-analysis, including a recent randomised phase 2 trial, suggests that outcomes might be improved further by using an adjuvant intravesical regimen that includes both Mitomycin (MM) and BCG. These promising findings require corroboration in a definitive, large scale, randomised phase 3 trial using standard techniques for intravesical administration. General Aim: To determine the efficacy and safety of MM in addition to BCG in patients with NMIBC. Design: Open label, randomised, stratified, 2-arm multicentre phase 3 clinical trial. Population: The target population is adults with resected, high-risk NMIBC (high grade Ta or any grade T1) suitable for intravesical chemotherapy treatment. Key eligibility criteria include: prior transurethral resection of all visible tumour, adequate organ function, and ECOG performance status 0-2. Study Treatments: Arm A: Intravesical BCG Alone (standard): Induction (weekly x 6), followed by Maintenance (monthly x 10); or Arm B: Intravesical BCG + MM (experimental): Induction (weekly x 9), followed by Maintenance (monthly x 9). Statistical Considerations: A sample size of 500 (followed until 213 events are observed) provides 85% power to detect a 10% improvement in disease free survival (DFS) rate at 2 years from 70% on BCG alone to 80% on BCG and MM (hazard ratio 0.63) at a significance level of 0.05, allowing for 10% non-compliance.