In summary, our findings suggest that both 4367_TCR-1 and TCR-2 specifically recognized the PIK3CAN345K mutation, shared the same HLA-class II restriction (HLA-DPA1*01:03/HLA-DPB1*04:01), and recognized and suppressed gene-engineered tumor cell lines that were capable of immunologically processing and presenting the mutated PIK3CA antigen. Here, HLA-DPB1 is linked to neoplasm.