PD-1 identifies the patient-specific CD8+ tumor-reactive repertoire infiltrating human tumors

Abstract

Adoptive transfer of tumor-infiltrating lymphocytes (TILs) can mediate regression of metastatic melanoma; however, TILs are a heterogeneous population, and there are no effective markers to specifically identify and select the repertoire of tumor-reactive and mutation-specific CD8 + lymphocytes. The lack of biomarkers limits the ability to study these cells and develop strategies to enhance clinical efficacy and extend this therapy to other malignancies. Here, we evaluated unique phenotypic traits of CD8 + TILs and TCR β chain (TCRβ) clonotypic frequency in melanoma tumors to identify patient-specific repertoires of tumor-reactive CD8 + lymphocytes. In all 6 tumors studied, expression of the inhibitory receptors programmed cell death 1 (PD-1; also known as CD279), lymphocyte-activation gene 3 (LAG-3; also known as CD223), and T cell immunoglobulin and mucin domain 3 (TIM-3) on CD8 + TILs identified the autologous tumor-reactive repertoire, including mutated neoantigen-specific CD8 + lymphocytes, whereas only a fraction of the tumor-reactive population expressed the costimulatory receptor 4-1BB (also known as CD137). TCRβ deep sequencing revealed oligoclonal expansion of specific TCRβ clonotypes in CD8 + PD-1 + compared with CD8 + PD-1 -TIL populations. Furthermore, the most highly expanded TCRβ clonotypes in the CD8 + and the CD8 + PD-1 + populations recognized the autologous tumor and included clonotypes targeting mutated antigens. Thus, in addition to the well-documented negative regulatory role of PD-1 in T cells, our findings demonstrate that PD-1 expression on CD8 + TILs also accurately identifies the repertoire of clonally expanded tumor-reactive cells and reveal a dual importance of PD-1 expression in the tumor microenvironment.

T cell receptor richness in peripheral blood increases after cetuximab therapy and correlates with therapeutic response

“…While HPV − HNC patients showed no detectable staining for HPV-specific multimers (not shown), a subset of HPV-16 HLA-A2:E7(11–20)-specific T cells detected in the circulation of HPV + patients were found to express PD-1 (8.5%, Figure 1(c)) as a marker of antigen experience and exhaustion. As PD-1 + T cells appear to be clonal expansions of anti-tumor effector cells in the tumor microenvironment, 7 the relationship between TCR and anti-tumor efficacy was further investigated, using a broader method than multi-color flow cytometry.

10.1080/2162402X.2018.1494112-F0001Figure 1. Antigen specific T cells of HNC patients express exhaustion markers . Antigen specific CD8 + T cells were identified using EGFR (853–861) -, MAGE (271–279) - and HPV-E7 (11–20) -specific tetramers/ pentamers and counter-stained with PD-1 and CTLA-4 (t test, HPV + n = 18, HPV − n = 18).

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“…In the tumor microenvironment, T cells expressing PD-1 have been identified as clonal expansion of tumor reactive T cell populations, thus representing functionally important components in order to eliminate tumor cells. 7 Furthermore, Gros and colleagues were able to recently identify PD1 + CD8 + T cells in circulation of three melanoma patients that targeted unique patient-specific neoantigens. 31 Our findings, that tumor antigen specific T-cells (including EGFR, MAGE and HPV) in the periphery express PD-1 and CTLA-4, support these observations.…”

“…In tumor infiltrating lymphocytes (TIL), TA-specific T cells have been shown to express activation markers such as programmed death-1 (PD-1) or cytotoxic T lymphocyte associated protein-4 (CTLA-4). 7 Immunotherapeutic approaches targeting these pathways have demonstrated good clinical responses in a variety of tumor types. 8–11 Still, in the case of TA-specific immunity, the role of different treatment modalities on TCR properties and their therapeutic consequences is poorly understood.…”

Blockade of LAG3 enhances responses of tumor-infiltrating T cells in mismatch repair-proficient liver metastases of colorectal cancer

“…LAG3 expression is upregulated on T cells after activation and differentiation, 54 , 55 and intra-tumoral T cells that recognize tumor antigens are characterized by expression of LAG3 and other inhibitory receptors. 56 Although chronic tumor antigen stimulation in the tumor microenvironment can induce T cell exhaustion with simultaneous induction of high expression of multiple inhibitory receptors, this does not mean that all CD8 + TIL which express one or more inhibitory receptors at any level are functionally exhausted. Indeed, a recent mouse study showed that tumor antigen-specific TIL which expressed LAG3 or PD-1 produced IFN-γ in situ and had cytolytic potential.…”

Antigen-specificity and DTIC before peptide-vaccination differently shape immune-checkpoint expression pattern, anti-tumor functionality and TCR repertoire in melanoma patients

“…In fact, besides its inhibitory effect on T-cell function, mainly exerted by dephosphorylating CD28, 14 PD-1 has recently been shown to be highly expressed in the effector phase of T cells, particularly in melanoma-reactive and clonally expanded CD8 + T-cells. 15 , 16 …”