#1068 Establishment of urine-derived tubuloid system from pediatric leukemia patients on methotrexate treatment

Abstract Background and Aims While nephrotoxicity has been reported across a wide range of medication classes, anticancer drugs are among the most common contributors to acute kidney injury (AKI). Many anticancer drugs exhibit a high rate of renal excretion, making it critical to adjust drug concentrations based on individual renal function to optimize treatment outcomes. Methotrexate, a cornerstone of first-line chemotherapy for pediatric leukemia patients, requires precise dosing to mitigate the risk of drug-induced AKI. Method In this study, we established kidney tubular epithelial organoids, also known as tubuloids, derived from the urine of pediatric leukemia patients undergoing methotrexate treatment. Clean mid-voided urine samples were collected from three patients to culture tubuloids and build a biobank of pediatric tubuloid models. Despite variability in methotrexate induction doses, all pediatric tubuloids displayed cystic epithelial structures, distinct from patient-derived tubuloids used as controls. Results Ex vivo methotrexate treatment of tubuloids demonstrated dose-dependent increases in renal injury markers, including NGAL, which correlated with clinical outcomes. Additionally, cytotoxicity assays revealed significant inter-individual variability in response to anticancer drugs, considerating the need for careful dosing strategies. Conclusion In conclusion, tubuloids derived pediatric leukemia patients effectively mimic anticancer drug-induced renal injury, demonstrating their potential as a platform for integrating clinical and in vitro based data to screen patients at risk of AKI. This newly developed tubuloid-based system offers a promising approach for tailoring chemotherapy dosing to optimize therapeutic efficacy and minimize nephrotoxicity.