Immunotherapy in Bacillus Calmette-Guerin (BCG) unresponsive nonmuscle invasive bladder cancer

A number of promising therapies for Bacillus Calmette-Guerin (BCG) unresponsive nonmuscle invasive bladder cancer (NMIBC) are in the pipeline. In this review, we discuss the history of immunotherapy for the treatment of NMIBC and future developments, focusing on novel intravesical treatments.

The term BCG unresponsive NMIBC encompasses patients with both BCG refractory and BCG relapsing disease. This definition was adopted to standardize inclusion criteria for patients enrolling in clinical trials in this setting. A host of intravesical immuno-oncologic therapies that include gene therapies, oncolytic viruses, cell surface molecule delivered immunotoxins, and cytokine driven agonism of cellular immunity, are in various phases of the drug development pipeline. In addition, pembrolizumab, an immune-checkpoint inhibitor, has recently been approved as a treatment option for BCG unresponsive NMIBC.

Patients with BCG unresponsive disease face many difficulties. Although radical cystectomy is the most effective treatment option for these patients, it is associated with significant morbidity, difficult recovery challenges, and refusal by many patients. Cancer immunotherapies may provide bladder sparing options for some patients who develop BCG unresponsive disease.