This NK cell maintained the breast cancer cells dormant in the liver by secreting interferon-γ (IFN-γ), while sustaining NK cell abundance with interleukin-15 (IL-15)-based immunotherapy succeeded to prevent liver metastases and prolong the survival in preclinical models.72 Conversely, bone forms an immunosuppressive environment mainly due to immature NK cells, a small number of cytotoxic T cells, a large number of myeloid progenitors and Treg.73 In a human bladder tumour xenografts model, researchers observed a high infiltration of bone marrow-derived host CD11b myeloid cells. This evidence concerns the gene IL15 and urinary bladder neoplasm.