Figure 2. The application of patient-derived xenograft (PDX) in screening predictive biomarkers and therapeutic targets for esophageal cancer therapy. Esophageal cancer tissues are obtained from patients and implanted into immunodeficient mice for PDX models establishment. With the PDX models, the treatment response of chemotherapeutic drugs, radiotherapeutic methods or targeted drugs are tested on these tumor xenografts. Subsequently, genome-wide sequencing techniques and expressional analysis are carried out to screen genes with differential expression, which are related to various therapeutic methods. Through bioinformatic analysis, potential biomarkers are selected from differentially expressed genes. Finally, clinical trials are designed and performed to validate the feasibility of these biomarkers.