Orthotopic Metastatic (MetaMouse) Models for Discovery and Development of Novel Chemotherapy

Currently-used rodent tumor models, including transgenic tumor models, or subcutaneously growing human tumors in immunodeficient mice, do not sufficiently represent clinical-cancer, especially with regard to metastasis and drug sensitivity. In order to obtain clinically-accurate models, we have developed the technique of surgical orthotopic implantation (SOI) to transplant histologically intact fragments of human cancer, including tumors taken directly from the patient, to the corresponding organ of immunodeficient rodents. It has been demonstrated in approx 100 publications describing 10 tumor types that SOI allows the growth and metastatic potential of the transplanted tumors to be expressed and reflect clinical cancer. These clinically-accurate and rel evant SOI models of human cancer have enabled discovery and evaluation of novel antitumor and antimetastatic agents including antiangiogenic drugs. The green fluorescent protein (GFP) and red fluorescent protein (RFP) genes, cloned from bioluminescent organisms, have now been introduced into a series of human and rodent cancer cell lines in vitro to stably express GFP and RFP in vivo in SOI mouse models. With these fluorescent tools, tumors and metastasis in host organs can be externally imaged down to the single-cell level. The combination of fluorescent protein-based imaging in SOI models enables real-time antitumor, antimetastatic, and antian giogenic drug evaluation including high-throughput in vivo screening. These SOI models are uniquely useful for innovative drug discovery and mechanism studies and serve as a bridge link ing preclinical and clinical drug development.