Patient-derived tumour xenografts as models for breast cancer drug development

Purpose of review Patient-derived xenografts (PDXs) are becoming increasing popular as a preclinical tool for evaluating novel therapeutic strategies in cancer. These models maintain the biological characteristics of the donor tumours and have a predictive power in the translation of cancer therapeutics into clinical settings. This review focuses on the rapidly growing body of literature on PDX models of breast cancer and their applications and challenges in cancer drug development. Recent findings Several articles in the last 2 years have reported that breast cancer PDXs can reproduce the phenotype and diversity of patients' tumours. This preservation of breast cancer biology involves a number of different aspects, including gene expression patterns, mutational status, drug response and tumour architecture. These models have been shown to be a valuable tool for the identification of new treatment targets, rational drug combinations, biomarkers and mechanisms of drug resistance. Summary The development of relevant, predictive models is key to increase the success rate for new drugs. PDX models of breast cancer hold the promise for the development of new and more efficient therapeutic strategies.