Fig. 3

Liquid Biopsy in Patient-Derived Models. a CTCs enriched and isolated from blood samples of cancer patients are injected subcutaneously or orthotopically into immunocompromised mice to develop CDXs. Phenotype characterization can confirm the CDXs' fidelity of the primary tumor. CDXs can also be used to test novel drugs and portray a comprehensive tumor genetic landscape. By collecting the blood sample and matched tumor tissue and purifying them into CTCs, CTC-specific signal pathways can be found with genomics, single-cell transcriptomics, proteomics, and metabolomics analysis. Ex vivo cultures of CDX cells can be utilized for drug screening and genome-wide analysis. CDX-derived organoids also need to undergo the phenotype characterization process so that they can be used as a drug testing and high-throughput screening platform and as genomic analysis materials. CDX-derived organoids and CDX cells are amenable to gene editing. b Extracellular vesicles and cfDNA/ctDNA can be isolated and analyzed in the plasma and serum from the PDX, CDX, and PDO models, which can apply to drug testing, biomarker discovery, and disease burden monitoring. The tumor-specific variants can be distinguished from the patient’s plasma and serum samples. What’s more, the patient-derived models provide a rapid platform to display the tumor genome landscape. CTC: circulating tumor cell; CDX: CTC-derived xenograft; PDX: patient-derived xenograft; cfDNA: cell-free DNA; ctDNA: circulating tumor DNA. By Figdraw