Malekzadeh et al. show that peripheral blood lymphocytes (PBL) contain a small fraction of mutated TP53 neoantigen-reactive T cells, which was consistent with tumor-infiltrating lymphocyte response to mutant TP53. In vitro stimulation (IVS) using either p53 neoantigen long peptide or tandem minigenes, with multiple hotspot TP53 mutations, followed by 4-1BB/OX40 enrichment, increased the frequency of PBL-derived reactive T cells to as high as 70%. IVS increased the TCRB clonality in PBL-derived T cells, and IVS T cells recognized naturally presented, HLA-restricted neoantigens.
Contributed by Shishir Pant
PURPOSE: The purpose of this study was to evaluate antigen experienced T cells in peripheral blood lymphocytes (PBL) for responses to p53 neoantigens. EXPERIMENTAL DESIGN: PBLs from patients with a mutated TP53 tumor were sorted for antigen-experienced T cells and in vitro stimulation (IVS) was performed with p53 neoantigens. The IVS cultures were stimulated with antigen-presenting cells expressing p53 neoantigens, enriched for 41BB/OX40 and grown with rapid expansion protocol. RESULTS: T-cell responses were not observed in the PBLs of 4 patients who did not have tumor-infiltrating lymphocyte (TIL) responses to mutated TP53. In contrast, 5 patients with TIL responses to mutated TP53 also had similar T-cell responses in their PBLs, indicating that the PBLs and TILs were congruent in p53 neoantigen reactivity. CD4(+) and CD8(+) T cells were specific for p53(R175H), p53(Y220C), or p53(R248W) neoantigens, including a 78% reactive T-cell culture against p53(R175H) and HLA-A*02:01. Tracking TCRB clonotypes (clonality, top ranked, and TP53 mutation-specific) supported the enrichment of p53 neoantigen-reactive T cells from PBLs. The same T-cell receptor (TCR) from the TIL was found in the IVS cultures in three cases and multiple unique TCRs were found in another patient. TP53 mutation-specific T cells also recognized tumor cell lines bearing the appropriate human leukocyte antigen restriction element and TP53 mutation, indicating these T cells could recognize processed and presented p53 neoantigens. CONCLUSIONS: PBL was a noninvasive source of T cells targeting TP53 mutations for cell therapy and can provide a window into intratumoral p53 neoantigen immune responses.
Author Info: (1) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (2) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (3) Surgery Branch, National Cancer Institute,
Author Info: (1) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (2) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (3) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (4) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (5) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (6) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (7) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (8) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (9) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (10) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (11) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (12) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (13) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (14) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (15) Hematopathology Section, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland. (16) Hematopathology Section, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland. (17) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (18) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (19) Surgery Branch, National Cancer Institute, Bethesda, Maryland. (20) Surgery Branch, National Cancer Institute, Bethesda, Maryland. sar@nih.gov. (21) Surgery Branch, National Cancer Institute, Bethesda, Maryland.
