Patient-derived tumor organoids for personalized cancer immunotherapy: An immunopeptidome-to-validation approach in RCC and BC.

Immunotherapy has revolutionized cancer treatment, yet clinical success remains limited, with only a fraction of patients responding. Tumor heterogeneity and patient-specificity hinder response prediction, emphasizing the need for human-based models that accurately reproduce tumor-immune interactions. Conventional preclinical platforms, such as murine models, lack the human-specific HLA-TCR complexity, limiting their ability to accurately evaluate immunotherapy responses. To address this, we established a patient-specific pipeline for precision immunotherapy in renal cell carcinoma (RCC) and bladder cancer (BC). Tumor and adjacent tissues were used to generate patient-derived tumor organoids (PDTOs) and patient-derived cells (PDCs) for immunopeptidome profiling. Using our in-house microfluidic platform, PeptiCHIP, we identified tumor-associated HLA-I peptides as potential T cell targets. Their immunogenicity was evaluated using peptide-expanded, HLA-matched peripheral blood mononuclear cells (PBMCs), revealing peptides capable of inducing antigen-specific CD8+ T cell activation and cytotoxicity against the patient's tumor. This study integrates PDCs, immunopeptidomics, and functional immune assays to design and test personalized cancer immunotherapies. By recreating patient-specific tumor-immune interactions ex vivo, our platform enables the discovery of therapeutic targets, the evaluation of immune responses, and validation in a patient-specific context. This approach demonstrates the feasibility of bridging a major gap in translational immunotherapy research and supports the development of personalized cancer immunotherapy strategies.