Lund University researchers showed that precision-cut bladder tumor slices can keep immune cells alive and functional ex vivo for up to six days. In experiments, the tissue-slice platform reproduced clinical response patterns to nivolumab, supporting its use as a more immune-relevant drug-testing model than purely tumor-cell assays. The method enables rapid ex vivo assessment while maintaining the tumor microenvironment’s immunologic features—an advantage for immunotherapy trials where T-cell engagement is central. If validated more broadly, the approach could reduce time-to-evidence and improve translational confidence for checkpoint inhibitor selection, especially when patient-specific immune context is needed.