Patient-derived xenografts (PDXs) as model systems for human cancer

•PDXs are obtained by growing human tumours into immunocompromised mice.•Expansion of tumours as PDXs provides unlimited material for molecular profiling.•PDXs allow studying response to chemical and biological treatments in vivo.•Cancer cells can be obtained from PDXs and used for in vitro studies.•Modelling metastasis and tumour-stroma interactions with PDXs.