Patient-derived d-MMR/MSI phenotype urachal cancer organoids for personalized drug screening.

Background: Urachal cancer (UrC) is a rare, aggressive malignancy typically diagnosed at advanced stages, where systemic treatment becomes necessary. However, cytotoxic chemotherapy offers limited efficacy, and prospective clinical trials are exceedingly difficult due to the rarity of the disease. Thus, robust Methods: Fresh UrC tumor samples were collected from patients undergoing en bloc resection and cultured to generate PDOs. These organoids were subjected to drug screening using standard chemotherapeutic agents. Whole-exome sequencing (WES) and RNA sequencing (RNA-seq) were conducted to compare the molecular profiles of the PDOs with their corresponding parental tumors. Associations between drug responses and genomic/transcriptomic features were analyzed. Student's Results: The established d-MMR/MSI phenotype UrC PDOs faithfully reproduced the genomic and transcriptomic landscapes of the original tumors, including intratumoral heterogeneity, and demonstrated consistent drug response profiles. Molecular characterization further revealed actionable targets within the RAS/MAPK and PI3K/AKT/mTOR pathways, as well as immune-related targets such as PD-L1. These findings highlight the utility of PDOs in modeling rare cancers and guiding personalized therapeutic strategies. Conclusions: d-MMR/MSI phenotype UrC PDOs recapitulate the phenotypic and molecular features of their parental tumors, capturing critical heterogeneity. As such, they represent a valuable platform for reflecting treatment responses, investigating resistance mechanisms, and developing individualized therapeutic regimens.