(A) Expression of 41BB on CD8⁺ T cells expressing HLA-A*68:01/p53^R248W neoantigen–specific TCR following coculture with autologous tumor cell line (TC), which was incubated with anti-HLA class I or II blocking antibodies or p53^R248W peptide. (B) Intracellular cytokine staining of cocultures of CD8⁺ T cells expressing HLA-A*02:01/p53^R175H neoantigen–specific TCR and Saos2 cells alone (HLA-A*02:01+ and p53^NULL; gray circles on left graph or gray dots on right plot) or overexpressing p53^R175H full-length protein (red squares on left graph or red dots on right plot). (C) Secretion of IFN-γ in cocultures of HLA-A*02:01/p53^Y220C neoantigen–specific T cells (CD8⁺-enriched TIL culture 4259-F1 from patient 5) with HLA-A*02:01–positive tumors from unrelated donors and Saos2 tumor cells overexpressing full-length p53^Y220C protein. > indicates 1,250 pg/ml IFN-γ. Data in panels B and C are mean ± SEM, n = 3 technical replicates, and 2-tailed Student’s t tests were performed for statistical analyses (**P < 0.01 and ***P < 0.001).