BCG plus mitomycin did not improve disease-free survival versus BCG alone in high-risk non-muscle-invasive bladder cancer patients

BACKGROUND AND OBJECTIVE: Intravesical bacillus Calmette-Guérin (BCG) plus mitomycin (MM) had not been compared rigorously with BCG alone in BCG-naïve, non-muscle-invasive bladder cancer (NMIBC) patients. METHODS: Participants with BCG-naïve NMIBC (high-grade pTa or any grade pT1; concurrent carcinoma in situ [CIS] allowed) were assigned randomly (1:1) to either the BCG + MM or the BCG-alone group after maximal transurethral resection. The primary endpoint was disease-free survival (DFS); the secondary endpoints included a complete response on cystoscopy at 3 mo (CR3mos), recurrence, progression, adverse events (AEs), and deaths from any cause. KEY FINDINGS AND LIMITATIONS: We randomised 501 participants (249 to BCG + MM and 252 to BCG alone), with pTa in 53%, pT1 in 47%, and concurrent CIS in 28%. The median follow-up was 48 mo. DFS was not superior for BCG + MM versus BCG alone (2-yr DFS rate: 75% vs 71%; hazard ratio 0.87, 95% confidence interval 0.65-1.16; p = 0.3). The numbers of events for BCG + MM versus BCG alone were as follows: 214 versus 210 (CR3mos), 79 versus 86 (recurrence), 28 versus 44 (progression), and 26 versus 23 (death). Those assigned BCG + MM had more instillations (4033 vs 3383) but fewer doses of BCG (total 2056 vs 3383; median nine vs 16) than BCG alone. Grade 3-5 AEs occurred in 43 assigned BCG + MM versus 37 assigned BCG alone. A higher number of participants assigned BCG + MM than those assigned BCG alone had ≥75% of their planned doses (78% vs 68%, p = 0.02). CONCLUSIONS AND CLINICAL IMPLICATIONS: BCG + MM was not proved superior to BCG alone, but required 39% fewer doses of BCG and fewer treatment discontinuations. These findings support consideration of BCG + MM as a pragmatic alternative to BCG alone, which could mitigate the global shortage of BCG.