IL15 and neoplasm: 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.