Objective·To establish a patient-derived tumor xenograft(PDX)model using tumor cells sourced from malignant pleural effusion(MPE)in patients with lung cancer,and to conduct experimental validation.Methods·Gene expression data were downloaded from the Gene Expression Omnibus(GEO),including single-cell RNA sequencing data for lung cancer with MPE(GSE131907)and for solid lung cancer(GSE203360).Data were clustered,and differential gene ontology functional enrichment analysis was performed to ascertain the feasibility of modeling by using MPE.MPE samples from patients with lung cancer were collected and processed through centrifugation and red blood cell lysis to enrich cells.The enriched cells were then implanted subcutaneously into non-obese diabetic/severe combined immunodeficient(NOD/SCID)mice.Tumor growth was monitored,and when tumors reached 1 000 mm3,they were passaged and preserved.Histopathological examination was conducted on stable passaged tumors,the cell morphology was observed via hematoxylin-eosin(H-E)staining and the expression of lung cancer biomarkers was detected by using immunohistochemistry(IHC).Results·Single-cell data analysis revealed stronger proliferative functions of tumor cells in MPE,suggesting that PDX modeling using MPE tumor cells may yield better tumor formation.A total of 35 samples of MPE from lung cancer patients were collected,and 13 PDX models were successfully constructed,with a success rate of 37.14％.Histopathological examination showed significant cellular atypia by H-E staining,and IHC result showed positive expression of lung cancer biomarkers such as cytokeratin 7(CK7),thyroid transcription factor-1(TTF1),and Napsin A.Conclusion·By enriching tumor cells from MPE of lung cancer patients,a more convenient,efficient,and dynamically modelable PDX model is successfully constructed.This model retains the malignant characteristics and protein expression features of tumor cells from lung cancer patients,providing an important experimental model tool for basic research and clinical drug guidance for lung cancer patients with MPE.