Towards best practice in establishing patient-derived xenografts

It is remarkable that human tumour tissues can be grown for months, or even years, as serially transplantable, patient-derived xenografts (PDXs) in immunocompromised mice. The grafting technique used has been refined over the last few decades, so it is now possible to successfully engraft most tumour types, albeit with varying take rates. This review focuses on the methodological requirements to establish successful PDXs. The first step is selecting viable tumour tissue from surgical resections of local or metastatic disease, ascites, pleural effusions, biopsies, circulating tumour cells, rapid autopsies or even organoids. Once grafts are prepared, sometimes with Matrigel or stroma, their likelihood of growing is affected by the strain of immunocompromised host mice and the graft site, which may be subcutaneous, subrenal capsule or orthotopic. Finally, once PDXs are established, authentication assays can be used to rule out possible misidentification or cross-contamination following serial passaging. By carefully optimising all of these steps, PDXs can be grown as efficiently as possible, providing invaluable models for preclinical cancer research.