No clinical benefit from sequential combination of mitomycin C plus bacillus Calmette-Guérin (BCG) than BCG alone in the adjuvant treatment of high risk non muscle invasive bladder cancer: result of a planned interim analysis of a prospective randomized trial.

Background: The aim of this study was to evaluate whether the sequential use of Mitomycin C (MMC) and Bacillus Calmette-Guérin (BCG) is superior to BCG alone in reducing the risk of disease recurrence in patients with non-muscle invasive bladder cancer (NMIBC) with high risk of progression.

Methods: Prospective randomized trial was conducted from March 2021 to March 2023 and included 72 patients with high risk NMIBC. Trial registration number: NCT03790384; EUDRACT Number: 2017-004540-37. Thirty-one patients underwent to BCG alone and forty-one to MMC plus BCG during the induction course. The BCG schedule comprised six weekly instillation of 81 mg Connaught strain BCG as the induction course, followed by a further three-monthly instillation at three, six and twelve months, as the maintenance course. Forty mg of MMC were administered the day prior to each weekly BCG instillation in BCG plus MMC arm. A planned interim analysis was carried out in June 2023, at the end of the 12mo follow-up period.

Results: Six out of thirteen 6/31(19.3%) and 10/41 (24.4%) patients experienced recurrence in BCG and BCG plus MMC group (P=0.611), respectively. BCG plus MMC did not improve Disease Free Interval (HR: 1.23 95% CI:0.46-3.50; P=0.640). Patients receiving sequential treatment experienced similar AEs (P>0.05) and more urinary symptoms (P<0.05).

Conclusions: This interim pre-planned analysis suggested absence of clinical advantages in terms of disease recurrence rate when MMC is administered one day prior to BCG during induction course.