Modeling breast cancer heterogeneity with patient-derived xenografts

To better understand the biology underlying breast cancer progression and improve the development and application of therapies, it is essential to model the heterogeneity inherent to breast cancer. The ability to graft patient tumor fragments into immune-deficient mice is enabling development of relatively large collections of unique breast cancer models. Several different techniques, including orthotopic and heterotopic implantations, are being used to generate breast cancer patient-derived xenograft (PDX), and the consensus across techniques is that molecular and phenotypic traits exhibited by the patient tumors are for the most part maintained in the xenografts, although some genetic drift has been reported. At present, pools of breast cancer PDXs are being used in preclinical testing, and the coming years will illuminate whether the use of PDXs enables broader preclinical testing and increased therapeutic success.