Narrative Review of Potential Non-Surgical Treatments for BCG-Unresponsive Non-Muscle Invasive Bladder Cancer

Intravesical Bacillus Calmette–Guérin (BCG) is a recommended therapy approach for non-muscle invasive bladder cancer (NMIBC) to prevent disease progression and eliminate tumor cells. Nevertheless, some patients have shown resistance to BCG therapy, exhibiting disease recurrence and progression to MIBC, thereby necessitating radical cystectomy as the best-recommended treatment option. However, radical cystectomy greatly affects postoperative morbidity and quality of life, rendering many patients hesitant or surgically unsuitable for this invasive therapy. The concept of bladder preservation has emerged as an alternative, employing a diverse array of therapeutic agents and interventions to improve therapeutic efficacy to retain the bladder for as long as possible. In this review, we explore various established therapeutic agents and ongoing clinical trials involving new potential agents and interventions. This study was undertaken to determine the advantage of each agent and their combined therapeutic regimens in improving prognostic efficacy, offering an alternative to radical cystectomy for BCG-unresponsive NMIBC.