Evolution of intravesical immunotherapy for bladder cancer: mycobacterial cell wall preparation as a promising agent

Abstract

Background: The intra-cavitary administration of antineoplastic agents for the treatment of non-invasive bladder cancer has met with variable results. Mytomicin-C is effective in the prevention of tumor recurrence when administered in the immediate post-resection period, but also exhibits activity against papillary tumors. It lacks efficacy in carcinoma in-situ (CIS) of the bladder. Bacillus Calmette-Guérin (BCG) has been shown to be effective against papillary tumors, but particularly in the treatment of CIS. Unfortunately, live BCG has serious safety limitations. Objective: To review the current situation with the use of non-viable preparations of mycobacteria (M. phlei) that have been investigated for the treatment of superficial bladder cancer in limited open-label clinical trials. Conclusion: MCC (Urocidin) has shown activity against a variety of tumor cells, both in vitro and in animal cancer models. Limited clinical trials have also shown it to be active against non-muscle invasive bladder tumors in patients who have previously failed one or more courses of chemotherapy and/or immunotherapy with BCG. An unique dual immunomodulatory and apoptotic mechanism of action has been proposed for MCC.