A Multicenter Study of 2-year Outcomes Following Hyperthermia Therapy with Mitomycin C in Treating Non-Muscle Invasive Bladder Cancer: HIVEC-E

Introduction: High grade, non-muscle invasive bladder cancer (NMIBC) is usually treated with intravesical Bacillus Calmette-Guérin. Chemohyperthermia therapy (CHT) may be a novel alternative therapy for the treatment of NMIBC.

Objective: To evaluate the recurrence-free survival (RFS) of patients treated with CHT using the Combat bladder recirculation system (BRS) for NMIBC.

Methods: This was a prospective multi-institutional study of 1,028 consecutive patients with NMIBC undergoing CHT between 2012 and 2020. A total of 835 patients were treated with CHT with Mitomycin C (MMC). Disease was confirmed on transurethral resection of bladder tumor (TURBT) prior to starting CHT. Follow-up included cystoscopy and subsequent TURBT if recurrence/progression was suspected. The primary endpoint was RFS. Secondary endpoints were progression-free survival (PFS) and adverse events from CHT.

Results and limitations: Median follow up was 22.4 months (Interquartile range (IQR): 12.8 -35.8). Median age was 70.4 years (IQR: 62.1 -78.6). A total of 557 (66.7%), 172 (20.6) and 74 (8.9%) of patients were classified to BCG naïve, BCG unresponsive and BCG failure, respectively. The RFS at 12 months and 24 months for BCG naïve was 87.6% (95% CI 85.0% - 90.4%) and 75.0% (95% CI 71.3% - 78.8%), respectively. The RFS at 12 months and 24 months for BCG unresponsive cohort was 78.1% (95% CI 72.0% - 84.7%) and 57.4% (95% CI 49.7% - 66.3%), respectively. The RFS at 24 months for the BCG unresponsive cohort for CIS with/without papillary disease and papillary only disease were 43.6% (95% CI 31.4% -60.4%) and 64.5% (95% CI 55.4% - 75.1%), respectively. Minor adverse events occurred in 216 (25.6%) patients and severe events occurred in 17 (2.0%) patients.

Conclusions: CHT with MMC using the Combat BRS is effective in the medium term and has a favorable adverse event profile.