Redirecting immune cells against bone metastases: Immunotherapy of prostate cancer metastases using genetically programmed immune effector cells.

Extract: Metastasis of the bone is common in two of the major gender-specific malignancies -- breast and prostate cancers. Although both primary breast and prostate cancer are manageable by "classical" therapies such as surgery, irradiation, and chemotherapy, when metastases (secondary cancers) disseminate to the bones these diseases are, by and large, incurable. Metastasis to the bone is implicated in around 70% of prostate and breast cancer deaths. The idea of harnessing the immune system to fight disseminated cancer has proven to be effective in experimental animal models against transplanted tumors. Here, both arms of the immune system, namely, the humoral one characterized by anti-tumor antibodies and the cellular one composed of a type of white blood cell, specifically the cytotoxic T-lymphocytes (CTLs), were found to cause tumor rejection either following immunization of the experimental mice before the tumor inoculations (active-vaccination) or after adoptive transfer of cancer-specific antibodies or CTLs into tumor-bearing mice (passive-vaccination). Encouraged by these results, scientists and clinicians have joined forces in extensive efforts to apply both active and passive vaccination for the immunotherapy of cancer patients. These attempts have flourished over the last fifteen years following the discovery of the first human tumor antigens in melanoma patients.