Establishment, functional dissection, and single-cell transcriptomal characteristics of patient-derived pulmonary sarcomatoid carcinoma organoids.

Background: Pulmonary sarcomatoid carcinoma (PSC) is a rare and highly aggressive subtype of non-small cell lung cancer with poor clinical outcomes. Progress in PSC research has been hindered by the lack of reliable preclinical models that faithfully recapitulate tumor heterogeneity and biological behavior. This study aimed to establish and characterize patient-derived organoid (PDO) models of PSC and evaluate their translational potential. Methods: Tumor tissues obtained from a surgically resected PSC patient were used to generate organoid cultures. Histopathological fidelity was assessed by hematoxylin and eosin staining and immunohistochemistry for CK, CK7, Vimentin, and BRG1. Tumorigenicity was evaluated using NOD-SCID gamma mouse xenograft models. Drug sensitivity to cisplatin and docetaxel was tested using ATP-based viability assays. Single-cell RNA sequencing was performed on matched primary tumors and organoids to compare cellular composition, transcriptomic profiles, and copy number variation (CNV) patterns. Results: Two stable PSC organoid lines (PDO1 and PDO2) were successfully established and maintained long-term in culture. Both organoids preserved the characteristic biphasic phenotype of PSC, showing co-expression of epithelial and mesenchymal markers. Xenograft experiments demonstrated robust tumorigenicity, with a 100% tumor formation rate, and xenograft tumors retained the histological architecture of the original tumor. Drug testing revealed heterogeneous chemosensitivity between the two organoid lines, with PDO1 showing greater sensitivity to cisplatin and docetaxel than PDO2. Single-cell transcriptomic analysis demonstrated that the organoids largely retained the malignant cellular populations, transcriptomic signatures, and CNV landscapes of the matched primary tumors. Correlation analysis of highly variable genes showed strong similarity between PDOs and their parental tumors (r = 0.7-0.8). Module score analysis revealed increased epithelial features and reduced mesenchymal features in organoids compared with matched primary tumors, indicating partial EMT state remodeling during Conclusion: We established and validated two PSC patient-derived organoid models that faithfully recapitulate key pathological, genomic, and functional features of the original tumors. These models provide a valuable platform for studying PSC biology, investigating tumor heterogeneity, and screening personalized therapeutic strategies for this rare and aggressive malignancy.