Tumor derived organoid was previously used as a tool to assess T cells’ antitumoral response via the contact between PBMCs and malignant cells.[15] Organoid was also reported as a model to assess the effects of immunotherapies, including the anti‐HER2‐chimeric antigen receptor (CAR) T cells and neoantigen EGFRvIII‐specific CAR NK cells in colorectal cancer.[16] In our study, five patient derived organoids distinctly attacked by peptide‐reactive T cells confirmed organoids as killing targets to assess the effect of neoantigen‐directed therapy. This evidence concerns the gene ERBB2 and colorectal cancer.