Intravesical MgSO4 for the treatment of BCG refractory T1 G3 bladder cancer: Preliminary results on efficacy and safety.

Abstract

An urgent need of therapy exists for patients with high-risk non-muscle invasive bladder cancer (NMIBC) for whom Bacillus Calmette-Guérin (BCG) refractory treatment has failed. We investigated the role of intravesical magnesium sulfate (MgSO4) therapy in the management of BCG refractory T1 high grade (G3) NMIBC. Between January 2018 and July 2021, we performed a prospective trial enrolling participants with T1 G3 NMIBC refractory in BCG therapy. All patients included were considered ineligible for or have refused to undergo radical cystectomy. Subjects are enrolled into a single treatment group of a fixed dose of intravesical MgSO4. The intravesical solution was given for 3 h bi-weekly × 6 then once per week for 12 months. Cystoscopic surveillance was performed every 3 months. Endoscopic resection was performed if suspicious findings were identified on surveillance cystoscopy to establish pathologic diagnosis. Oncological outcomes and any side effects were reported during follow-up. A total of 8 patients who received intravesical MgSO4 for refractory TG3 tumors were included in our study. The median follow-up time was 29 months (range from 23 to 36). 62.5% of the patients (5/8) achieved a complete response to intravesical MgSO4, while 25% of the patients (2/8) had a partial response and 12.5% (1/8) had persistent disease. None of the patients had disease progression. None of the patients experienced hypermagnesemia. In patients with pTG3 tumors who were refractory to BCG therapy, intravesical MgSO4 was a well-tolerated and potentially effective regimen.