Intravesical instillation of rBCG secreting certain cytokines, such as IFN-γ [35], IFN-α [43] or IL-15 [57], or various chimeric proteins in which GM-CSF is fused to cancer antigens [67,68,69], has been shown to result in prolonged survival and enhanced tumor growth suppression compared to the installation of pBCG in various mouse models of bladder cancer. Here, IL15 is linked to cancer.