Patient-derived xenografts, a multi-faceted in vivo model enlightening research on rare liver cancer biology

Modeling human cancer in pre-clinical models is of fundamental importance to gain a better understanding of the biological and molecular basis of the disease and to evaluate novel therapeutic strategies. To this end both in vitro and in vivo models are being developed with a clear emphasis on the effort to preserve the characteristics of the original human tumors both in terms of tissue architecture and clinically relevant drug responses. Recent major improvements in 3D culture conditions now allow growth of organoids from several human cancers allowing unprecedented potential for disease modeling and high-throughput screening (1). The complexity of the interactions taking place between cancer cells and their environment can however be fully recapitulated only in vivo. In this context patient-derived xenografts (PDXs) which are obtained by direct implant of primary human tumor tissue fragments in immunocompromised mice and subsequent expansion as tumor explants (‘never in vitro’) are emerging as extremely valuable tools to evaluate novel therapeutic strategies and biomarkers in oncology due to their ability to closely mirror the original patient’s tumor (2,3).