What makes patient-derived xenograft orthotopic models better than traditional PDX or CDX models?

Orthotopic PDX models have gained prominence in basic and translational cancer research because they are more clinically relevant than traditional subcutaneous or cell-line-derived PDX models. They preserve the histological architecture, stroma construction, and gene-expression or mutation status of original tumor tissue and they replicate the human tumor microenvironment, which is critical to cancer progression and metastasis. O-PDX models can predict the development of resistance to first-line therapy and response to second-line therapy — before these events are observed in patients.