An essential feature of cancer is its ability to evade the immune system. Multiple mechanisms are used for this purpose, including the disruption of antigen presentation and suppression of the immune response. The latter mechanism involves the activation of T-cell inhibition by recruiting regulatory T cells that weaken this response. Recent progress in understanding the ability of cancer to evade the immune system has paved the way to develop strategies to reverse this process and reactivate the immune system. Particularly, immune checkpoint signaling between T cells and tumor cells has been targeted with a new class of drug, immune checkpoint inhibitors. Immunotherapy has been an established and effective treatment in bladder cancer since 1976 when Morales and colleagues demonstrated that intravesical treatments with bacillus Calmette-Guérin can treat carcinoma in situ and prevent nonmuscle invasive urothelial cancer recurrence. 1,2 This treatment elicits a cytotoxic response via antigenic presentation by bladder tumor cells.