Pembrolizumab and BCG Solution in Treating Patients With Recurrent Non-Muscle-Invasive Bladder Cancer

The purpose of this study is to evaluate the efficacy (the effect of drug on tumor) and the tolerability (the effect of drug on the body) of pembrolizumab, when given as a single agent in patients with bladder tumors. Another purpose of the study is to see what tumor characteristics are associated with increased efficacy of the pembrolizumab. Pembrolizumab (MK-3475) is an antibody (a human protein that sticks to a part of the tumor and/or immune cells) designed to allow the body's immune system to work against tumor cells. Pembrolizumab is Food and drug Administration (FDA) approved for the treatment of advanced melanoma (a type of skin cancer) and some types of lung cancer. It is not yet approved by the United States Food and Drug Administration (USFDA) for bladder cancer, hence it is considered an investigational agent for this disease.