Establishment of a Co-culture System of Patient-Derived Colorectal Tumor Organoids and Tumor-Infiltrating Lymphocytes (TILs).

Colorectal cancer (CRC) is the third most common cancer worldwide. Tumor-infiltrating lymphocytes (TILs) have been identified as an important prognostic marker in CRC. The therapeutic application of TILs has already shown promising results in melanoma and cervical cancer. However, their use in CRC therapy remains in an exploratory phase. A suitable in vitro model to evaluate TIL efficacy is currently unavailable, hindering further advancements in this field. Patient-derived organoid (PDO) models, which closely retain the characteristics of the original tumor tissue and reflect inter-patient heterogeneity, provide an excellent platform for studying the interaction between CRC and TILs. In this study, a method is described to establish a patient-derived CRC organoid model from freshly resected tumor tissue, followed by isolation and expansion of TILs. This system allows co-culture of CRC organoids and TILs, enabling the assessment of TIL-mediated cytotoxicity and immune responses. By analyzing TIL killing efficacy on organoids, the potential outcomes of TIL-based immunotherapy for personalized CRC treatment can be predicted. Moreover, further engineering of TILs may enhance their anti-tumor efficacy, offering a promising strategy for developing more effective cellular therapies. This PDO-TIL co-culture model provides a powerful tool for preclinical evaluation of TIL therapies and personalized treatment strategies in CRC.