The use of intravesical BCG in urothelial carcinoma of the bladder.

Omar Alhunaidi,Alexandre R Zlotta

doi:10.3332/ecancer.2019.905

Abstract

The high recurrence and progression rates of non-muscle invasive bladder cancer (NMIBC) have led investigators to study the use of intravesical therapy in order to prevent them. Bacillus Calmette–Guérin (BCG) has been successfully used for this indication to treat NMIBC for more than four decades.BCG is the only intravesical agent shown to reduce the risk of progression of NMIBC to muscle-invasive disease. Despite over 40 years of clinical use, the precise mechanism of action for what has often been considered the most successful cancer immunotherapy in humans remains largely unknown.Unfortunately, BCG therapy is not a universal panacea and it still fails in up to 40% of patients. Many of these patients, especially in the high-risk category (T1 high-grade disease, carcinoma in situ) will require aggressive therapy like cystectomy or in selected cases, bladder-sparing options like chemo-radiation. Indeed, there is no gold standard intravesical treatment after BCG failure.

Highlights

A meta-analysis by Malmström and colleagues showed that intravesical Bacillus Calmette–Guérin (BCG) with maintenance course has 32% reduction in risk of recurrence compared to Mitomycin C (MMC) intravesical chemotherapy [38]
A number of randomised controlled trials have studied the use of Electromotive Drug Administration (EMDA) of intravesical MMC in non-muscle invasive bladder cancer (NMIBC) but evidence remains lacking on the use of EMDA-MMC in patients who have become unresponsive to BCG therapy
After four decades of use, the exact mechanism of action remains unknown and further studies would be helpful to augment its efficacy

Summary

Introduction

While hundreds of thousands of patients have been treated with BCG for prevention of NMIBC, no clinical difference has been shown among studies despite the use of various strains worldwide. This absence of long-lasting immune activation after a single 6-week course of BCG could be related to the increased clinical efficacy observed with BCG maintenance instillations. For high-risk patients, the 3 years regimen was superior in reducing the recurrences compared to the 1-year course [33].

Results

Conclusion