To test this, we conducted in vitro cytotoxicity assays with HLA-A*02:01 and MAGEA4 (A2M4) TCR-engineered T cells (TCR-T) against the U2-OS osteosarcoma cell line, which naturally expresses HLA-A*02:01 and MAGEA4. The gene discussed is HLA-A; the disease is osteosarcoma.