Short form for “patient derived xenografts,” are models of cancer where the tissue or cells from a person’s tumour are implanted into an immunodeficient or “humanized” mouse (a mouse with functioning human genes, cells, tissues, and/or organs). PDX models simulate the person’s cancer and can be used to identify and test different treatment options before using them in the person. [Adapted from Lai Y et al. (2017). Current status and perspectives of patient-derived xenograft models in cancer research. Journal of Hematology & Oncology, 10(1):106. https://jhoonline.biomedcentral.com/articles/10.1186/s13045-017-0470-7]