Primary tumor grafts as advanced models for breast cancer that authentically reflect tumor histopathology, growth, metastasis, and patient outcomes (copy number)

Development and pre-clinical testing of new cancer therapies is limited by the scarcity of in vivo models that authentically reproduce tumor growth and metastatic progression. We report new models for breast tumor growth and metastasis, in the form of transplantable tumors derived directly from individuals undergoing treatment for breast cancer. These tumor grafts represent the diversity of human breast cancer and maintain essential features of the original tumors, including metastasis to specific sites. Co-engraftment of primary human mesenchymal stem cells maintains phenotypic stability of the grafts and increases tumor growth by promoting angiogenesis. We also report that tumor engraftment is a prognostic indicator of disease outcome for newly diagnosed women; orthotopic breast tumor grafting marks a step toward individualized models for tumor growth, metastasis, and prognosis. This bank of tumor grafts also serves as a publicly available resource for new models in which to study the biology of breast cancer.