Efficacy of hyperthermic-intra-vesical chemotherapy in patients with BCG-refractory nonmuscle-invasive bladder cancer.

4592 Background: In Bacillus Calmette-Guérin (BCG) refractory non-muscle-invasive bladder cancer (NMIBC), radical cystectomy is the standard of care. For patients unwilling or unable to undergo cystectomy, alternative intravesical therapies are currently being investigated to minimize the risk of recurrence and progression. Chemohyperthermia by HIVEC (Hyperthermic-Intra-Vesical Chemotherapy) is a therapeutic option in BCG-refractory patients. The objective of our study was to evaluate the 2-year oncological results of HIVEC in BCG-refractory patients. Methods: Between June 2016 and September 2021, patients treated with HIVEC (6 weekly instillations) for BCG-refractory NMIBC were prospectively included in our study. These patients had a theoretical indication for cystectomy but were ineligible for surgery or refused it. The primary endpoint was 1-year recurrence-free survival (RFS) rate. Secondary endpoints were 6-month complete response rate for Cis, 1-year overall and cancer-specific survival rates and bladder preservation rate. Results: Seventy patients, mean age 70 [42-89] years, were treated consecutively. After a mean follow-up of 20.9 months, 32 patients recurred (mean time of 10.6 months) and 7 patients finally had a cystectomy. The recurrence-free survival rate was 53.1% at 1 year and 20.5% at 2 years. Six patients progressed to a muscle-invasive disease, after a mean delay of 6.7 months. Four of them experienced metastatic progression and died from bladder cancer. Cancer-specific and overall survival rates were 95.1% and 92.9% at 1 year, and 87.5% and 77.8% at 2 years. The bladder preservation rate was 90%. For patients with Cis (34% of the entire series), the 6-month complete response rate was 75%. The presence of Cis was not a predictive factor of response to HIVEC. Tolerance was excellent with 38.2% grade 1-2 adverse events and no grade 3-4 adverse events. Conclusions: Chemohyperthermia using the HIVEC device achieved a RFS rate of 53.1% at 1 year and enabled a bladder preservation rate of 90%. While cystectomy remains the standard of care, HIVEC may be discussed cautiously for patients who are not eligible for surgery and well informed of the risk of progression to muscle-invasive disease.