To explore the applicability of PDOs in immunotherapy, we established a PDO‐PBMC co‐culture system and generated autologous tumor‐reactive T cells.[7a] To test the practicality of our PDOs co‐culture model, we used it to investigate the influence of EZH2 inhibition, and we demonstrated that it could support autologous tumor‐reactive T cells in killing tumor cells. This evidence concerns the gene EZH2 and neoplasm.