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T Cell Dysfunction in Cancer Immunity and Immunotherapy

Anliang Xia, Yan Zhang, Jiang Xu and 2 more

Frontiers in Immunology · 2019 · Review · CC BY

doi:10.3389/fimmu.2019.01719

Abstract

In cancer, T cells become dysfunctional owing to persistent antigen exposure. Dysfunctional T cells are characterized by reduced proliferative capacity, decreased effector function, and overexpression of multiple inhibitory receptors. Due to the presence of various inhibitory signals in the complex tumor microenvironment, tumor-specific T cells have distinct dysfunction states. Therapeutic reactivation of tumor-specific T cells has yielded good results in cancer patients. Here, we review the hallmarks of T cell dysfunction in cancer. Also, we discuss the relationship between T cell dysfunction and cancer immunotherapy.

Full text

From PubMed Central, U.S. National Library of Medicine, as current on Oct 18, 2026. Paragraph numbers are ours, so an answer can point at one.

Introduction

T cells can take part in a variety of immune responses that arise in various diseases, including infection, cancer, autoimmune diseases, and allergic diseases. In acute infections, naive T cells, upon antigen stimulation, are rapidly activated and differentiate into effector T cells (Teff). Teff differentiation involves transcriptional, epigenetic and metabolic reprogramming as well as the acquisition of effector features. After antigen clearance, most Teff die, but a small fraction of them differentiate into memory T cells, which quickly respond when the same antigen reappears. Memory T cells downregulate their effector program and own self-renewal ability driven by IL-7 and IL-15 in an antigen-independent manner. By contrast, during chronic infections and cancer, the function of T cells becomes compromised, termed T cell dysfunction, due to persistent antigen exposure. Previous studies have demonstrated that the severity of dysfunction is associated with the level of antigen stimulation. Furthermore, specific T cell receptor (TCR)-dependent pathways, for instance, those mediated by nuclear factor of activated T cells (NFAT) and sprouty homolog 2 (SPRY2), have been shown to be involved in T cell dysfunction, in line with the effects of ongoing TCR stimulation. In addition, chronic antigen stimulation also results in persistent expression of programmed cell death protein 1 (PD-1) by NFAT cytoplasmic 1 (NFATc1). PD-1 may further regulate the level of TCR signaling. Therefore, the extent and persistence of antigenic stimulation appear to be vital factors leading to T cell dysfunction and are associated with the severity of dysfunction.

T cell exhaustion is a representative of T cell dysfunction. Exhausted T cells (Tex) differ from other dysfunctional T cells, including anergic T cells and senescent T cells. Anergic T cells are induced by suboptimal stimulation, whereas senescent T cells enter a terminally differentiated state due to repeated stimulation, which involves irreversible cell cycle arrest and telomere shortening (Figure 1). In this article, we mainly discuss the exhausted T cells. T cell dysfunction was first discovered in mice infected with chronic lymphocytic choriomeningitis virus (LCMV), which is characterized by a progressive loss of function including proliferation, cytokine production and the ability to lyse target cells. Subsequently, T cell dysfunction was described in humans with chronic viral infections and cancer. The acquired dysfunction was related to the co-expression of multiple inhibitory receptors (IRs) including PD-1, cytotoxic T lymphocyte antigen 4 (CTLA-4), T-cell immunoglobulin domain and mucin domain-3 (Tim-3), lymphocyte activation gene 3 (LAG-3), T cell immunoreceptor with Ig and ITIM domains (TIGIT), and others. Interestingly, studies in mice and humans have shown that dysfunctional CD8+ T cells coupregulate multiple IRs, and the type and amount of IRs are associated with the severity of the T cell dysfunction. It is worth noting that dysfunctional T cells are not completely useless. Instead, these cells retain a certain level of residual function, and this residual function may be critical in vivo, limiting persistent pathogen infection and tumor progression. However, dysfunctional T cells fail to effectively eliminate infection and cancer.

Reversal of T cell dysfunction is becoming more important in improving immunity to cancer. Immune checkpoint blockade, as one modality of cancer immunotherapy, is designed to enhance T cell function and thus exert an effective anti-tumor T cell response. One of the major markers of T cell dysfunction is the overexpression of PD-1. Blocking PD-1 or its ligand PD-L1 successfully reactivates T cell function, emphasizing the importance of the PD-1/PD-L1 axis in reversing T cell dysfunction. Encouraging results have been observed in a variety of cancer types, such as melanoma, urothelial cancer and non-small-cell lung cancer (NSCLC), with the use of antibodies targeting PD-1/PD-L1. However, most patients do not maintain sustained responses to this therapy. The lack of a long-lasting response may be partly explained by the presence of other inhibitory receptors in T cells.

Here, we review the hallmarks of T cell dysfunction in cancer. Also, we discuss the relationship between T cell dysfunction and cancer immunotherapy.

Inhibitory Receptors in Dysfunctional T Cells

One of the traits of dysfunctional T cells is the increased and sustained expression of multiple inhibitory receptors, including PD-1, CTLA-4, Tim-3, and LAG-3 (Figure 3a). In general, the number of inhibitory receptors expressed by dysfunctional T cells is positively associated with T cell dysfunction. In other words, the greater the number, the more serious the dysfunction. Additionally, functional effector T cells can transiently express inhibitory receptors upon activation. For instance, PD-1 expression rapidly increases after T cell activation and may remain at moderate levels in healthy individuals. To control autoreactivity and immunopathology, inhibitory receptors play a key negative regulatory role. In healthy adults, for example, circulating PD-1+CD8+ T cells are not representative of dysfunctional T cells, but instead are representative of effector memory cells. In addition, IR expression patterns in dysfunctional T cells also have differences between cancer and infection, albeit with many common features. B- and T-lymphocyte attenuator (BTLA) is upregulated in dysfunctional CD8+ T cells in cancer, but is absent in dysfunctional CD8+ T cells in LCMV. This finding shows that the molecular mechanisms that cause IR upregulation and T cell dysfunction may be somewhat different between chronic infections and cancer.

Moreover, each IR binds to its ligand, which is typically expressed by antigen presenting cells (APCs) and tumor cells in the tumor microenvironment (TME), to affect T cell survival, proliferation and function (Figure 2). In view of this, the availability and amount of ligands in the TME is critical for IR to play a negative regulatory role in CD8+ T cells. As one of the ligands for PD-1, the expression of PD-L1 in the TME relies on exposure to inflammatory cytokines. Conversely, CD155 and CD112, as TIGIT ligands, are continuously expressed in the TME by most melanoma cells and APCs. In addition, Tim-3 directly binds to Galectin-9 and CEACAM1 to inhibit T cell function. Also, Tim-3 can bind to phosphatidylserine and the DNA binding protein HMGB1.

The molecular mechanisms of IR-mediated immunomodulation of T cells have not been fully elucidated. There are several possible mechanisms to support IR-mediated immune regulation. First, IR competes with costimulatory receptors for binding to its ligand to prevent the formation of microclusters and lipid rafts. For instance, CTLA-4 can compete with the costimulatory molecule CD28 to bind to CD80 and CD86, while TIGIT can compete with CD226 to bind to the same ligands CD112 and CD155. The imbalance in the expression levels of IR and costimulatory receptors affects the same ligand binding. In patients with metastatic melanoma, CD8+ TILs upregulate TIGIT and downregulate CD226, leading to an imbalance of TIGIT/CD226 expression. This imbalance may be conducive to inhibiting T cell responses to tumors in the TME, besides T cell inhibition mediated by TIGIT itself. Second, activation of T cells by TCR or costimulatory receptors is disrupted by negative signals mediated by PD-1 and CTLA-4. When TIGIT/CD155 is ligated, APCs produce IL-10, which also inhibits T cell function. In addition, CD28 can also be expressed by PD-1+ T cells. CD28, as a costimulatory molecule, stimulates the activation of naive T cells and promotes cytokine secretion. Recent studies have revealed that the PD-1/PD-L1 axis inhibits T cell function through inactivation of CD28 signaling. In a mouse model, conditional knockout of CD28 abolishes the effects of PD-1 blockade. This suggests that the CD28/B7 pathway may act as an important role in the efficacy of anti-PD-1 therapy.

Accumulated evidence shows that simultaneous blockade of multiple inhibitory receptors is more effective than single IR blockade in reversing dysfunctional CD8+ T cells in vitro and in vivo. For example, blockade of PD-1 combined with blockade of CTLA-4, Tim-3, LAG-3, or TIGIT blockade, to some extent, can reverse T cell dysfunction and enhance antitumor immunity. These inhibitory receptor molecules are derived from different structural families and have different intracellular signaling domains. They can bind to ligands with different expression patterns.

Inhibitory Cells in the Tumor Microenvironment (TME)

The TME contains a variety of cell types that participate in various biological processes, which promote or inhibit tumor progression. Immunosuppressive cells are present in the TME and contribute to T cell dysfunction. These inhibitory cells include regulatory T cells (Treg cells), tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), cancer-associated fibroblasts and adipocytes, and endothelial cells (Figure 3b).

Treg cells, as a major group of infiltrating CD4+ T cells in the TME, can significantly inhibit the antitumor immunity mediated by T cells. Treg cells usually disrupt the activation, proliferation, and survival of effector T cells by producing immunosuppressive molecules, including transforming growth factor-β (TGF-β) and interleukin-10 (IL-10). Notably, multiple IRs are upregulated in highly inhibitory Treg cells, including PD-1, CTLA-4, Tim-3, and TIGIT. Of course, they also upregulate molecules associated with T cell dysfunction or trafficking, including CCR4, CD39, and CD73, as well as members of the TNF receptor superfamily, such as GITR and OX40. Therefore, antibodies targeting CTLA-4, CCR4, and/or GITR on Treg cells can deplete Treg cells, reverse T cell dysfunction, and restore T cell antitumor immunity and immune surveillance on cancer cells.

TAMs suppress T cell antitumor immunity and promote tumor development, involving functions such as the sustained accumulation of Treg cells and dysregulation of the vasculature due to the expression of chemokines and amino acid-degrading enzymes, such as arginase 1 and indoleamine-2,3-dioxygenase (IDO). Similarly, MDSCs enter TME aberrantly, produce nitric oxide and reactive oxygen species, and express arginase 1 and IDO, thereby effectively promoting T cell dysfunction. In a mouse model, targeting MDSCs with monoclonal antibodies has been demonstrated to restore the antitumor immune responses and tumor killing ability of tumor-infiltrating T lymphocytes (TILs).

Cancer-associated fibroblasts can secrete cytokines and chemokines, and disrupt the deposition of the extracellular matrix, which shapes the structure of the TME and thus contributes to tumorigenesis. T cell dysfunction can also be caused by cancer-associated fibroblasts via the production of TGF-β and vascular endothelial growth factor (VEGF). Moreover, recent findings have also shown that cancer-associated adipocytes impair antitumor immunity and promote tumor malignancy in several cancers. The mechanism may be mediated by the metabolic and paracrine regulation of tumor infiltrating immune cells and cancer cells.

Endothelial cells may promote T cell dysfunction by improving the production of prostaglandin E2 (PGE2) and CD95L, while impairing T cell recruitment by reducing the expression of vascular cell adhesion molecule 1 (VCAM1). The underlying mechanisms of these changes are mediated by hypoxia and VEGF signaling in endothelial cells. In addition, metabolic communication between cancer and endothelial cells, as well as lymphatic endothelial cells, may help impede antitumor T cells and mediate immunosuppression.

Suppressive Soluble Mediators

Some soluble molecules are present in the TME that mediate T cell dysfunction. These molecules include IL-10, type I IFNs, IDO, adenosine, VEGF-A, TGF-β, and IL-35 (Figure 3c).

IL-10 is produced by various immune cells and serves as an effective antiinflammatory molecule. For instance, natural killer cells, APCs, T cells, and B cells can generate IL-10. Interestingly, the dose of IL-10 and the state of T cell activation can affect the effects of IL-10 on T cells in vivo. On the one hand, IL-10 impairs antitumor immunity and promotes tumor growth in mouse models. Simultaneous blockade of PD-1 and IL-10 results in increased survival and delays tumor growth in ovarian cancer, leading to an enhanced antitumor immune response and reduced infiltration of immunosuppressive MDSCs. On the other hand, high doses of IL-10 and PEGylated IL-10 hamper the progression of tumors in animals and increase the expansion and function of CD8+ TILs expressing elevated IL-10R. Thus, IL-10 may have a paradoxical effect on T cells in vivo.

Type I IFNs including IFNα and IFNβ may be typical cytokines with a dual role. As key pro-inflammatory cytokines, type I IFNs inhibit viral replication by directly inducing antiviral activity and activating innate immune cells. Additionally, type I IFN signaling facilitates the optimal priming of T cells and production of functional effector T cells and memory T cells. However, some studies have also shown that IFNα promotes the persistence of viruses in chronic infections and induces T cell dysfunction. During the first few days of LCMV infections, blockade of IFNα can effectively prevent the occurrence of T cell dysfunction. The mechanism by which IFNα promotes T cell dysfunction may be through the production of immunosuppressive molecules, such as IL-10, PD-L1, and IDO, as well as the stimulation and maintenance of PD-1 expression on T cells. Notably, IFNα blockade combined with PD-1 blockade effectively enhances antitumor immune responses in tumor-bearing mice.

IDO is expressed by tumor cells, APCs and CD8+ T cells in the TME. IDO activates Tregs by producing kynurenine and inhibits T cell function by depleting the essential amino acid tryptophan. In addition, resistance to anti-PD-1 and anti-CTLA-4 mAbs is closely related to IDO. Adenosine exerts an inhibitory role and directly impedes effector T cell function by activating the adenosine receptor A2aR. Indirect destruction of effector T cell function is induced by increased Treg function, decreased APC activation, and MDSC induction. Moreover, VEGF-A is generated by tumor cells in the TME. In addition to its proangiogenic properties, VEGF-A inhibits dendritic cell maturation, increases the accumulation of MDSCs and induces Tregs, all of which contribute to the formation of an immunosuppressive TME milieu. Coexpression of various IRs is increased by VEGF-A in a VEGF-R2- and NFAT-dependent manner, including PD-1, CTLA-4, and Tim-3. In addition, TGF-β is involved in T cell dysfunction in cancer. TGF-β inhibits antitumor immunity and shapes the TME by impeding T cell infiltration.

IL-35 is expressed by activated Treg cells and regulatory B cells. A recent study showed that Treg-derived IL-35 could promote T cell exhaustion. The underlying mechanism was direct regulation of Blimp1 expression in CD8+ T cells, increased IR expression and restricted differentiation of central memory CD8+ T cells. In addition, neutralization of IL-35 promotes CD8+ TIL proliferation and production of inflammatory cytokines. Neutralization of IL-35 also decreases tumor growth in a mouse tumor model. These results indicate that IL-35 favors the immunosuppressive TME.

Metabolic Pathways in the TME

The activation of T cells and exertion of antitumor immunity depend on some common metabolic pathways, such as aerobic glycolysis, amino acid metabolism, glutaminolysis and de novo fatty acid synthesis. These metabolic pathways are also important for cancer cell proliferation and survival. Hence, within the TME, T cells compete with cancer cells to obtain adequate nutrients (Figure 3d).

Recently, some studies have demonstrated that cancer cells compete with TILs to acquire the essential glucose, which results in less availability of glucose to T cells. The reduction or deprivation of glucose induces T cell dysfunction and impairs the immune response. Therefore, restraining the metabolic activity of tumor cells may have potential value in increasing the amount of glucose available to T cells, thereby improving the antitumor activity of T cells. Moreover, glycolysis is required for T cell maturation, expansion and effector function. The CD28 signaling pathway can facilitate the transition of T cell metabolism to glycolysis. Therefore, both PD-1 and CTLA-4 can restrict T cell glycolysis by interfering with CD28 signaling. Compared to CTLA-4, PD-1 can also induce the fatty acid β-oxidation (FAO) rate-limiting enzyme carnitine palmitoyl transferase (Cpt1a) to simultaneously promote FAO. Notably, the role of PD-1 in inducing FAO relies on the simultaneous inhibition of the PI3K/AKT and MEK/ERK signaling pathways, which regulate glucose metabolism. Blocking PD-1 or CTLA-4 restores the glycolytic ability of TILs in a mouse model, which promotes glycolysis in T cells. It is noteworthy that PD-L1 derived from tumor cells can facilitate tumor glycolysis through AKT/mTOR signaling. Thus, blocking the PD-1/PD-L1 axis can lead to a range of synergistic antitumor effects: restoring tumor-specific T cell function, reducing tumor glycolysis, and improving glucose availability to T cells in the TME.

Of course, certain amino acids, including arginine, glutamine and tryptophan, are also important nutrients that stimulate T cell activation and promote cancer cell proliferation and survival. For instance, arginine is a nutrient necessary for T cell activation and proliferation. TAMs and MDSCs express arginase 1, which decomposes and reduces arginine in the TME, and results in impaired effector T cell function. Interestingly, for T cell activation and differentiation, glutamine is essential. However, cancer cells exert a strong intake of glutamine, which is conducive to tumor development. It is well known that the rate-limiting enzyme for glutamine decomposition is glutaminase. In a mouse model, targeting glutaminase is effective in controlling tumor occurrence. Therefore, we can infer that excessive glutaminolysis in the TME is due to cancer cells, which restricts the utilization of glutamine by T cells and thereby promotes T cell dysfunction. Moreover, because tumor cells and suppressive immune cells secrete the tryptophan metabolism enzyme IDO, tryptophan is catabolized into kynurenine, an immunosuppressive metabolite. Accumulated kynurenine facilitates regulatory T cell production. Collectively, these results indicate that in the TME, T cells can effectively exert antitumor immunity, which is inseparable from some important nutrients. These essential nutrients may be controlled by cancer cells and immune regulatory cells.

In addition to nutrients, various metabolites are also involved in T cell dysfunction, such as lactic acid, low pH, and hypoxia (Figure 3d). Tumor-derived lactic acid can induce apoptosis in naive T cells, which may support tumor immune escape, due to the loss of the 200 kDa FAK family interacting protein. Lactic acid induces pH alterations and a loss of cytosolic NAD+ regeneration, which further limits T cell activity and cytokine production. Thus, neutralizing acidic components in the TME may contribute to enhancing T cell antitumor immunity. Notably, hypoxia is another metabolic parameter in the TME due to rapid tumor growth. Different studies have shown that hypoxia improves or impairs T cell immune responses. In murine chronic infections and tumor models, results indicate that hypoxia can enhance the cytotoxic function of T cells as well as lead to more effective viral and tumor control. By contrast, increased expression and activity of the transcription factor hypoxia-inducible factor 1α (HIF-1α) is induced by hypoxia, which increases the expression of inhibitory receptors on T cells and reduces T cell effector function.

Epigenetic Imprinting of T Cell Dysfunction

The epigenetic imprinting of dysfunctional T cells differs from that of effector/memory T cells (Figure 3e). Normally, PDCD1 (encoding PD-1) is temporarily demethylated in activated T cells, after which normal methylation levels are restored. In chronic viral infections, results indicate that the PDCD1 demethylation levels persist in activated T cells, leading to long-term expression of PD-1 and T cell dysfunction. Even after the virus is cleared to levels that cannot be detected by current technologies, this demethylation pattern of the PDCD1 locus is still sustained, suggesting that this epigenetic program has been fixed. Interestingly, one study reported the presence of two T cell clones with different affinities in Melan-A-specific TILs in human melanoma. Low avidity T cell clones, due to the sustained methylation of the PDCD1 promoter, do not express PD-1 even when stimulated by TCR. Conversely, antigen-specific T cells with high functional avidity express PD-1. These phenomena suggest a relationship among expression of PD-1, modification of the PDCD1 locus and intensity of TCR signaling. Aside from the continued demethylation of the PDCD1 locus, dysfunctional T cells gradually undergo de novo methylation of genes involved in effector functions during persistent infections and tumor progression, limiting T cell expansion and clonal diversity. This cannot be reversed by PD-1 blockade. However, during PD-1 blockade, blocking dysfunction-related methylation imprinting has a synergistic effect in a murine tumor model, as manifested by increased T cell immune responses and tumor control.

In addition, unique changes in chromatin accessibility occur in dysfunctional T cells. For example, in chronic LCMV infection, additional accessible regions of PDCD1 appeared in dysfunctional T cells. However, some open regions of the IFNG locus were present in functional T cells and were absent in dysfunctional T cells. It is worth noting that after anti-PD-1 treatment, these accessible areas specific to the dysfunctional state did not significantly change, showing that the epigenetic program was only minimally remodeled. Similarly, tumor antigen-specific and bystander T cells were adoptively transferred in a murine tumor model. Gene expression and chromatin accessibility were then compared. The results showed that only tumor-specific T cells were characterized by dysfunction and exhibited increased effector functions after anti-PD-L1 therapy, with little change in chromatin accessibility.

Moreover, epigenetic imprinting begins in the early stages of dysfunction. Many changes in dysfunctional T cells in advanced tumors of mouse liver cancer models are also present in T cells from precancerous lesions. Two different chromatin states can mirror the process of moving from mild dysfunction in early tumor lesions to more severe dysfunction in late-stage tumors. On the one hand, the chromatin state of early dysfunctional TILs shows partial plasticity and can be reprogrammed by anti-PD-1 therapy. On the other hand, the advanced state is fixed and cannot be changed by anti-PD-1 therapy. It is noteworthy that most of the overlap exists between the chromatin accessibility state of PD-1hi CD8+ TILs from human non-small-cell lung cancer and the chromatin accessibility state of late TILs in mice. Thus, PD-1/PD-L1 blockade in human tumors may only cause transcriptional rewiring rather than altering the chromatin accessibility pattern itself.

Transcriptional Regulation of T Cell Dysfunction

Transcriptional regulation of T cell dysfunction involves changes in the expression patterns and transcriptional connection of some important transcription factors. Some transcription factors are expressed in both functional Teff and dysfunctional T cells (Figure 3f). However, in dysfunctional T cells, these transcription factors are linked to different genes and transcriptional loops, showing activity in specific contexts.

T-bet and Eomes, as T-box family transcription factors, play a crucial role in the development of effector and memory CD8+ T cells. In acute infection, T-bet promotes the formation of Teff cells and the development of KLRG-1+ terminal Teff cells, while Eomes promotes the expression of IL-15Rβ and the development of memory T cells in a homeostatic manner. However, in chronic infection, the role of T-bet and Eomes is different from their function in Teff and Tmem cells. For example, the formation of a dysfunctional T cell population requires the participation of both T-bet and Eomes. And if either transcription factor is genetically deleted, the dysfunctional T cell population cannot form. Furthermore, due to its potential ability to inhibit the transcription of the IR genes (e.g., Pdcd1 encoding PD-1), upregulated expression of T-bet favors the formation of progenitor PD-1int Eomeslo Tex subpopulation. As for Eomes, its high expression in the terminal Tex subpopulation differs from that in the self-renewal Tmem cells in acute infection. In view of this, transcriptional network analysis is performed, and it has been shown that Eomes participates in almost completely different transcription networks in functional Teff and Tmem cells compared with Tex cells. Therefore, the functions of T-bet and Eomes are rewiring in Tex cells.

Other transcription factors are also involved in T cell dysfunction. Foxo1, Blimp-1, NFAT, IRF-4, and BATF can promote or antagonize T cell dysfunction by modulating dysfunction or effector-specific genes, respectively. The expression level of these transcription factors directly affects their capability of driving distinct transcriptional programs. For instance, dysfunctional T cells upregulate Foxo1 and Blimp-1, which act as positive regulators of T cell dysfunction. Also, metabolic-related transcription factors, including hypoxia-inducible factor (HIFs) and von Hippel-Lindau (VHL) complexes, may promote T cell dysfunction in some cases. In addition, recent research has found that TOX, as a new transcription factor, promotes T cell dysfunction in cancer.

Heterogeneity in Dysfunctional T Cells

Dysfunctional T cells are heterogeneous. Firstly, PD-1 and CD44 are utilized to distinguish subpopulations of dysfunctional T cells with various biological functions. Studies have revealed that PD-1intCD44hi T cells had a lower degree of dysfunction than PD-1hiCD44int T cells, which may be partially explained by lower coexpression of IRs. Furthermore, the PD-1int T cells can produce a therapeutic response to PD-1 blockade. Conversely, PD-1hiCD44int T cells are in a terminally dysfunctional state and have no therapeutic response to immune checkpoint blockade. Subsequent studies have also shown that the PD-1intCD44hi T cell subpopulation is mainly composed of T-bethi and Eomeslo cells, and as a progenitor cell population, can persistently generate PD-1hiCD44intEomeshi T cell population with terminal dysfunction state.

In addition, the understanding of dysfunctional T cell heterogeneity is further improved due to the recognized role of CXCR5 and the transcription factor Tcf-1. The CXCR5+Tcf-1+Tim-3− T cell subpopulation can respond to PD-1 blockade and produce a more terminal CXCR5−Tcf-1−Tim-3+ T cell subpopulation. Interestingly, there is no difference in the expression of the transcription factors T-bet and Eomes between the two subpopulations. These results may reveal the heterogeneity in the original PD-1int progenitor cell populations.

Therefore, the heterogeneity of dysfunctional T cells is complex. Identifying progenitor populations that respond to checkpoint blockade may be more beneficial to the development of cancer immunotherapy and to cancer patients.

Single or Combined Immune Checkpoint Blockade

Immunotherapy for treating tumor-induced T cell dysfunction has provided hope to patients with cancer. Currently, immunotherapy has focused on blocking immune checkpoints in patients with various solid and hematological tumors. The most commonly targeted immune checkpoints are PD-1 and CTLA-4. Generally, PD-1 impedes T cell function by interfering with T cell receptor (TCR) signaling, whereas CTLA-4 impedes T cell function by competing with the costimulatory molecule CD28 to bind to CD80/CD86. Since Treg cells also express CTLA-4, antibodies targeting CTLA-4 can inhibit Treg cell function or enhance antitumor immunity by selectively eliminating Treg cells in a mouse model. The CTLA-4 targeting agent, ipilimumab, was the first immune checkpoint inhibitor. With the use of ipilimumab, overall survival was significantly increased in patients with advanced melanoma. Of note, in patients with melanoma treated with anti-CTLA-4, the melanoma-reactive CD8+ T cell response in peripheral blood was found to be significantly increased. This result suggests that enhanced T cell priming also plays a role. Also, PD-1 pathway blockade can effectively reverse dysfunctional T cells and increase antitumor activity in patients with various cancers, especially in viral infection-driven cancers or carcinogen-induced cancers. In addition, as mentioned above, recent studies have revealed that the PD-1/PD-L1 axis inhibits T cell function through the inactivation of CD28 signaling instead of TCR signaling. In a mouse model, conditional knockout of CD28 abolished the effects of PD-1 blockade, suggesting that the CD28/B7 pathway may act as an important role in the efficacy of anti-PD-1 therapy. Currently, five anti-PD-1 or anti-PD-L1 antibodies have been approved by the FDA for the treatment of a variety of cancers, including hepatocellular carcinoma, renal cell carcinoma and Hodgkin's disease.

Moreover, compared with monotherapy, the combined use of anti-CTLA-4 and anti-PD-1 has demonstrated prolonged progression-free survival and significant tumor regression in clinical trials of cancer patients. Also, PD-1 blockade combined with other checkpoint blockades, such as Tim-3, LAG-3, or TIGIT, significantly reverses T cell dysfunction and enhances antitumor immunity in patients with cancer, compared to individual checkpoint blockade. At present, humanized anti-TIM3 (TSR-022), anti-LAG3 (MK-4280), and anti-TIGIT (BMS-986207) antibodies against various cancers are under clinical trials. However, the underlying precise mechanisms to explain the efficacy of immune checkpoint blockade have not been fully described.

Immune Checkpoint Blockade in Combination With Other Immunotherapies

The combination of inhibitory receptor blockade and costimulatory molecule targeting exerts a synergistic effect in re-activating tumor-specific T cells. CD137 (or 4-1BB), a member of the TNFR family, is expressed on activated T cells. In a murine model, the combination of agonistic anti-CD137 antibodies and PD-1 blockade effectively controls tumor growth. This combination therapy also improves the T cell response to tumor antigens and promotes effector/memory CD8+ T cell formation. Another member of the TNFR family, OX40, is primarily expressed on activated CD4+ T cells. And its expression on CD8+ T cells is at a lower level upon TCR triggering. The research results show that OX40 agonists play an antitumor immunity-promoting role in immunogenic mouse tumor models, but do not play an effective role in tumor control in a poor immunogenic tumor model. Strikingly, in a vaccination setting, the addition of PD-1 blockade to OX40 agonists virtually eliminates the antitumor effect of OX40 monotherapy due to the reduced TIL infiltration and enhanced cell death of tumor-reactive CD8+ T cells. This effect deserves close attention because it is uncertain whether a similar harmful effect will occur in human cancers. Also, this phenomenon underscores the importance of the timing of different immunotherapeutic interventions to avoid the negative effects of T cell overstimulation.

Furthermore, anti-CTLA-4 therapy in combination with anti-VEGF antibodies has been shown to increase antitumor immune responses and achieve encouraging clinical results in patients with metastatic melanoma. Moreover, in mice with melanoma, researchers have demonstrated that the use of PPARα agonists can promote fatty acid catabolism in vaccine-induced CD8+ TILs. The addition of anti-PD-1 antibodies obviously enhanced the antitumor efficacy.

Therefore, future research should focus on how combination therapies should be applied and which dysfunctional states may be best for them.

CAR-T Cell Therapy

A CAR-T cell is genetically modified to express an antigen-specific, non-MHC restricted receptor, which consists of the single-chain variable fragment (scFv) of an antibody, a transmembrane domain and an intracellular signaling domain. Thus far, CAR-T cell therapy has achieved great success in treating hematological malignancies. However, some patients still lack response and relapse after receiving CAR-T treatment, possibly due to the poor proliferative capacity and the short duration of T cells. Therefore, a transcriptomic analysis was conducted to compare T cells from chronic lymphocytic leukemia (CLL) responders and non-responders after CAR-T treatment. The results showed that T cells from non-responders upregulated pathways associated with exhaustion and apoptosis compared to T cells from responders. Inhibitory receptors were also upregulated on these CAR-T cells, indicating that these inhibitory molecules may result in dysfunction and poor persistence of CAR-T cells.

Recently, CRISPR-Cas9 technology has been applied to knock out IR itself, and studies have been conducted on PD-1 and LAG-3 in CD19-BBζ CAR-T cells. In mouse xenograft models, knockout of IR-derived CAR-T cells effectively eradicated tumors. This method has also been applied to solid tumors. CRISPR-Cas9 was utilized to knock out PD-1 in CD133-specific CAR-T cells. In a mouse glioma model, CD133-specific CAR-T cells with PD-1 knockout enhanced the control of tumor growth compared to control CD133-CAR-T cells. Based on the encouraging results obtained above, CAR-T cells edited by CRISPR-Cas9 have entered clinical trials. For example, CD19-specific CAR-T cells with PD-1 knockout are being investigated in PhaseIclinical trials (NCT03298828).

Additionally, CAR-T cells are designed to secrete immune checkpoint antibodies themselves. In CD19+ lung cancer xenograft models, CAR-T cells have been engineered to secrete anti-PD-1 antibodies and significantly improved antitumor activity, manifested by enhanced T cell proliferation, increased cytotoxicity, and prolonged overall survival. Compared with standard CAR-T cells, anti-CAIX CAR-T cells secreting anti-PD-L1 antibodies significantly increase antitumor activity, as evidenced by enhanced cytokine production and immune cell recruitment and the significant reduction in tumor size in the humanized ccRCC mouse model. Whether these CARs are likely to succeed in the body is still unknown. Currently, CAR-T cells, which are designed to secrete PD-1, CTLA-4 or PD-L1 antibodies, have entered clinical trials for cancers expressing MUC1, EGFR, EGFRVIII, and mesothelin.

In addition, other strategies have been used to enhance CAR-T cell function in TME, including inhibition of inhibitory soluble molecules such as IDO, adenosine and VEGF, and protection from immunosuppression of non-tumor cells, such as MDSCs and TAMs. Interestingly, the combination of EGFRVIIICAR-T cells with the blockade of IDO1 significantly reduces tumor growth in a xenograft colon cancer model. In HER2 CAR-T cells, blockade of adenosine 2A receptor enhances CAR- T cell activation and cytokine production, which contributes to the improved antitumor efficacy of CAR-T cells. The addition of PD-1 blockade further enhanced T cell immunity. Also, VEGF blockade has achieved success in solid tumors including melanoma, and VEGF-targeted CAR-T cells have achieved good results in a variety of preclinical solid tumor models.

Challenges and Possible Solutions

Resistance to therapy is a major challenge in cancer immunotherapy. Defects involved in IFNγ signaling and antigen presentation pathways, as tumor-intrinsic alterations, can lead to resistance to cancer immunotherapy, which explains why immunotherapy is not effective in some cancer patients. In melanoma patients treated with PD-1 blockade, for example, the acquired resistance is attributed to the inactivation of IFNγ signaling and defects in the antigen presentation mechanism.

Moreover, alterations in the functional state of TILs are also among the reasons for resistance to immunotherapy. Interestingly, after adoptive transfer of MART-1 TCR-transduced T cells in advanced melanoma patients, the T cell functional phenotype was altered during relapse, which was characterized by a complete loss of initial cytotoxic activity or an acquired inflammatory cytokine secretion but lack of cytotoxicity. Therefore, to assess whether changes in the dysfunctional state are also critical in mediating the immunotherapeutic resistance of cancer patients, it will be of value to compare monotherapy and combination therapy at the beginning of treatment and at the moment of resistance.

In addition, reactivation of treatment-induced tumor-specific T cells may unexpectedly promote the further progression of T cell dysfunction. By comparing longitudinal samples of colon cancer models in both immunocompetent and immunodeficient mice, we found two important tumor escape mechanisms involving the accumulation of immunosuppressive cell populations (e.g., Tregs) and enhanced expression of multiple inhibitory receptors on T cells, which contribute to the deterioration of T cell function. Given this, Chauvin et al. discovered that, after PD-1 blockade in vitro, TIGIT expression was increased on TA-specific CD8+ T cells. Dual TIGIT and PD-1 blockade could promote the effector function of CD8+ T cells. Similarly, Tim-3 was upregulated on TILs in a PI3K/AKT-dependent manner upon PD-1 blockade. Notably, the combined blockade of the two receptors significantly improved antitumor immunity. In a mouse lung cancer model, several other immune checkpoints, such as CTLA-4, Tim-3, and LAG-3, were also found to be upregulated upon resistance to PD-1 blockade. Therefore, upregulation of other immune checkpoints also provides a potential resistance mechanism after anti-PD-1 treatment.

Conclusions

Dysfunctional T cells have various cellular states and different characteristics in cancer. Both persistent TCR triggering and T-cell internal and external factors can affect the fate of dysfunctional T cells. Although the characteristics of T cell dysfunction in cancer are similar to those of T cell dysfunction in chronic viral infection, there are various factors in the complicated TME that promote the process of immunosuppression, which can further shape T cell dysfunction in cancer. Gradually, it is conceivable that dysfunctional T cells in cancer differ from those found in chronic infection sites. However, heterogeneous dysfunctional T cell states still exist among different tumors and even within tumors. To reverse dysfunctional T cells and restore antitumor immunity, immune checkpoint blockade and related combination therapies have been applied. However, some challenges still remain to be solved, such as how to maintain long-lasting efficacy and how to choose the best combination therapy. Moreover, it is essential to understand the processes that drive and maintain these different dysfunctional T cell states. Continued advances in technology will help achieve this goal, supporting the development of personalized strategies for targeting dysfunctional T cells to achieve precise treatment for cancer patients.

Author Contributions

AX conceived and wrote the manuscript and prepared the figures. YZ and JX contributed to performing the literature collection. TY and X-JL directed and approved the manuscript. All authors declare no conflict of interest and gave the final approval of the manuscript submission.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References 212

  1. 1.

    Kaech SM Cui W. Transcriptional control of effector and memory CD8+ T cell differentiation. Nat Rev Immunol. (2012 ) 12:749–61.

    Not in our library10.1038/nri3307

  2. 2.

    Cui W Kaech SM. Generation of effector CD8+ T cells and their conversion to memory T cells. Immunol Rev. (2010 ) 236:151–66.

    Not in our library10.1111/j.1600-065x.2010.00926.x

  3. 3.

    Wherry EJ Blattman JN Murali-Krishna K van der Most R Ahmed R. Viral persistence alters CD8 T-cell immunodominance and tissue distribution and results in distinct stages of functional impairment. J Virol. (2003 ) 77:4911–27.

    Not in our library10.1128/jvi.77.8.4911-4927.2003

  4. 4.

    Wherry EJ Ha SJ Kaech SM Haining WN Sarkar S Kalia V. Molecular signature of CD8+ T cell exhaustion during chronic viral infection. Immunity. (2007 ) 27:670–84.

    Not in our library10.1016/j.immuni.2007.09.006

  5. 5.

    Baitsch L Baumgaertner P Devevre E Raghav SK Legat A Barba L. Exhaustion of tumor-specific CD8(+) T cells in metastases from melanoma patients. J Clin Invest. (2011 ) 121:2350–60.

    Not in our library10.1172/jci46102

  6. 6.

    Wherry EJ Kurachi M. Molecular and cellular insights into T cell exhaustion. Nat Rev Immunol. (2015 ) 15:486–99.

    Not in our library10.1038/nri3862

  7. 7.

    Schietinger A Philip M Krisnawan VE Chiu EY Delrow JJ Basom RS. Tumor-specific T cell dysfunction is a dynamic antigen-driven differentiation program initiated early during tumorigenesis. Immunity. (2016 ) 45:389–401.

    Not in our library10.1016/j.immuni.2016.07.011s

  8. 8.

    Bucks CM Norton JA Boesteanu AC Mueller YM Katsikis PD. Chronic antigen stimulation alone is sufficient to drive CD8+ T cell exhaustion. J Immunol. (2009 ) 182:6697–708.

    Not in our library10.4049/jimmunol.0800997

  9. 9.

    Blackburn SD Shin H Haining WN Zou T Workman CJ Polley A. Coregulation of CD8+ T cell exhaustion by multiple inhibitory receptors during chronic viral infection. Nat Immunol. (2009 ) 10:29–37.

    Not in our library10.1038/ni.1679

  10. 10.

    Agnellini P Wolint P Rehr M Cahenzli J Karrer U Oxenius A. Impaired NFAT nuclear translocation results in split exhaustion of virus-specific CD8+ T cell functions during chronic viral infection. Proc Natl Acad Sci USA. (2007 ) 104:4565–70.

    Not in our library10.1073/pnas.0610335104

  11. 11.

    Chiu YL Shan L Huang H Haupt C Bessell C Canaday DH. Sprouty-2 regulates HIV-specific T cell polyfunctionality. J Clin Invest. (2014 ) 124:198–208.

    Not in our library10.1172/jci70510

  12. 12.

    Martinez GJ Pereira RM Aijo T Kim EY Marangoni F Pipkin ME. The transcription factor NFAT promotes exhaustion of activated CD8(+) T cells. Immunity. (2015 ) 42:265–78.

    Not in our library10.1016/j.immuni.2015.01.006

  13. 13.

    Oestreich KJ Yoon H Ahmed R Boss JM. NFATc1 regulates PD-1 expression upon T cell activation. J Immunol. (2008 ) 181:4832–9.

    Not in our library10.4049/jimmunol.181.7.4832

  14. 14.

    Honda T Egen JG Lammermann T Kastenmuller W Torabi-Parizi P Germain RN. Tuning of antigen sensitivity by T cell receptor-dependent negative feedback controls T cell effector function in inflamed tissues. Immunity. (2014 ) 40:235–47.

    Not in our library10.1016/j.immuni.2013.11.017

  15. 15.

    Okazaki T Chikuma S Iwai Y Fagarasan S Honjo T. A rheostat for immune responses: the unique properties of PD-1 and their advantages for clinical application. Nat Immunol. (2013 ) 14:1212–8.

    Not in our library10.1038/ni.2762

  16. 16.

    Wherry EJ. T cell exhaustion. Nat Immunol. (2011 ) 12:492−9.

    Not in our library10.1038/ni.2035

  17. 17.

    Akbar AN Henson SM. Are senescence and exhaustion intertwined or unrelated processes that compromise immunity? Nat Rev Immunol. (2011 ) 11:289–95.

    Not in our library10.1038/nri2959

  18. 18.

    Schietinger A Greenberg PD. Tolerance and exhaustion: defining mechanisms of T cell dysfunction. Trends Immunol. (2014 ) 35:51–60.

    Not in our library10.1016/j.it.2013.10.001

  19. 19.

    Zajac AJ Blattman JN Murali-Krishna K Sourdive DJ Suresh M Altman JD. Viral immune evasion due to persistence of activated T cells without effector function. J Exp Med. (1998 ) 188:2205–13.

    Not in our library10.1084/jem.188.12.2205

  20. 20.

    Ahmadzadeh M Johnson LA Heemskerk B Wunderlich JR Dudley ME White DE. Tumor antigen-specific CD8 T cells infiltrating the tumor express high levels of PD-1 and are functionally impaired. Blood. (2009 ) 114:1537–44.

    Not in our library10.1182/blood-2008-12-195792

  21. 21.

    Fourcade J Kudela P Sun Z Shen H Land SR Lenzner D. PD-1 is a regulator of NY-ESO-1-specific CD8+ T cell expansion in melanoma patients. J Immunol. (2009 ) 182:5240–9.

    Not in our library10.4049/jimmunol.0803245

  22. 22.

    Day CL Kaufmann DE Kiepiela P Brown JA Moodley ES Reddy S. PD-1 expression on HIV-specific T cells is associated with T-cell exhaustion and disease progression. Nature. (2006 ) 443:350–4.

    Not in our library10.1038/nature05115

  23. 23.

    Woo SR Turnis ME Goldberg MV Bankoti J Selby M Nirschl CJ. Immune inhibitory molecules LAG-3 and PD-1 synergistically regulate T-cell function to promote tumoral immune escape. Cancer Res. (2012 ) 72:917–27.

    Not in our library10.1158/0008-5472.can-11-1620

  24. 24.

    Johnston RJ Comps-Agrar L Hackney J Yu X Huseni M Yang Y. The immunoreceptor TIGIT regulates antitumor and antiviral CD8(+) T cell effector function. Cancer Cell. (2014 ) 26:923–37.

    Not in our library10.1016/j.ccell.2014.10.018

  25. 25.

    Chauvin JM Pagliano O Fourcade J Sun Z Wang H Sander C. TIGIT and PD-1 impair tumor antigen-specific CD8(+) T cells in melanoma patients. J Clinl Invest. (2015 ) 125:2046–58.

    Not in our library10.1172/jci80445

  26. 26.

    Fourcade J Sun Z Benallaoua M Guillaume P Luescher IF Sander C. Upregulation of Tim-3 and PD-1 expression is associated with tumor antigen-specific CD8+ T cell dysfunction in melanoma patients. J Exp Med. (2010 ) 207:2175–86.

    Not in our library10.1084/jem.20100637

  27. 27.

    Fourcade J Sun Z Pagliano O Guillaume P Luescher IF Sander C. CD8(+) T cells specific for tumor antigens can be rendered dysfunctional by the tumor microenvironment through upregulation of the inhibitory receptors BTLA and PD-1. Cancer Res. (2012 ) 72:887–96.

    Not in our library10.1158/0008-5472.can-11-2637

  28. 28.

    Sharma P Allison JP. The future of immune checkpoint therapy. Science. (2015 ) 348:56–61.

    Not in our library10.1126/science.aaa8172

  29. 29.
  30. 30.

    Robert C Ribas A Wolchok JD Hodi FS Hamid O Kefford R. Anti-programmed-death-receptor-1 treatment with pembrolizumab in ipilimumab-refractory advanced melanoma: a randomised dose-comparison cohort of a phase 1 trial. Lancet. (2014 ) 384:1109–17.

    Not in our library10.1016/s0140-6736(14)60958-2

  31. 31.

    Motzer RJ Escudier B McDermott DF George S Hammers HJ Srinivas S. Nivolumab versus everolimus in advanced renal-cell carcinoma. N Engl J Med. (2015 ) 373:1803–13.

    Not in our library10.1056/nejmoa1510665

  32. 32.

    Fehrenbacher L Spira A Ballinger M Kowanetz M Vansteenkiste J Mazieres J. Atezolizumab versus docetaxel for patients with previously treated non-small-cell lung cancer (POPLAR): a multicentre, open-label, phase 2 randomised controlled trial. Lancet. (2016 ) 387:1837–46.

    Not in our library10.1016/s0140-6736(16)00587-0

  33. 33.
  34. 34.

    Araki K Youngblood B Ahmed R. Programmed cell death 1-directed immunotherapy for enhancing T-cell function. Cold Spring Harb Symp Quant Biol. (2013 ) 78:239–47.

    Not in our library10.1101/sqb.2013.78.019869

  35. 35.

    Duraiswamy J Ibegbu CC Masopust D Miller JD Araki K Doho GH. Phenotype, function, and gene expression profiles of programmed death-1(hi) CD8 T cells in healthy human adults. J Immunol. (2011 ) 186:4200–12.

    Not in our library10.4049/jimmunol.1001783

  36. 36.

    Sharpe AH Wherry EJ Ahmed R Freeman GJ. The function of programmed cell death 1 and its ligands in regulating autoimmunity and infection. Nat Immunol. (2007 ) 8:239–45.

    Not in our library10.1038/ni1443

  37. 37.

    Taube JM Anders RA Young GD Xu H Sharma R McMiller TL. Colocalization of inflammatory response with B7-h1 expression in human melanocytic lesions supports an adaptive resistance mechanism of immune escape. Sci Trans Med. (2012 ) 4:127ra37.

    Not in our library10.1126/scitranslmed.3003689

  38. 38.

    Huang YH Zhu C Kondo Y Anderson AC Gandhi A Russell A. CEACAM1 regulates TIM-3-mediated tolerance and exhaustion. Nature. (2015 ) 517:386–90.

    Not in our library10.1038/nature13848

  39. 39.

    Zhu C Anderson AC Schubart A Xiong H Imitola J Khoury SJ. The Tim-3 ligand galectin-9 negatively regulates T helper type 1 immunity. Nat Immunol. (2005 ) 6:1245–52.

    Not in our library10.1038/ni1271

  40. 40.

    Chiba S Baghdadi M Akiba H Yoshiyama H Kinoshita I Dosaka-Akita H. Tumor-infiltrating DCs suppress nucleic acid-mediated innate immune responses through interactions between the receptor TIM-3 and the alarmin HMGB1. Nat Immunol. (2012 ) 13:832–42.

    Not in our library10.1038/ni.2376

  41. 41.

    Freeman GJ Casasnovas JM Umetsu DT DeKruyff RH. TIM genes: a family of cell surface phosphatidylserine receptors that regulate innate and adaptive immunity. Immunol Rev. (2010 ) 235:172–89.

    Not in our library10.1111/j.0105-2896.2010.00903.x

  42. 42.

    Linsley PS Greene JL Brady W Bajorath J Ledbetter JA Peach R. Human B7-1 (CD80) and B7-2 (CD86) bind with similar avidities but distinct kinetics to CD28 and CTLA-4 receptors. Immunity. (1994 ) 1:793–801.

    Not in our library10.1016/s1074-7613(94)80021-9

  43. 43.

    Bottino C Castriconi R Pende D Rivera P Nanni M Carnemolla B. Identification of PVR (CD155) and Nectin-2 (CD112) as cell surface ligands for the human DNAM-1 (CD226) activating molecule. J Exp Med. (2003 ) 198:557–67.

    Not in our library10.1084/jem.20030788

  44. 44.

    Yu X Harden K Gonzalez LC Francesco M Chiang E Irving B. The surface protein TIGIT suppresses T cell activation by promoting the generation of mature immunoregulatory dendritic cells. Nat Immunol. (2009 ) 10:48–57.

    Not in our library10.1038/ni.1674

  45. 45.

    Egen JG Allison JP. Cytotoxic T lymphocyte antigen-4 accumulation in the immunological synapse is regulated by TCR signal strength. Immunity. (2002 ) 16:23–35.

    Not in our library10.1016/s1074-7613(01)00259-x

  46. 46.

    Joller N Hafler JP Brynedal B Kassam N Spoerl S Levin SD. Cutting edge: TIGIT has T cell-intrinsic inhibitory functions. J Immunol. (2011 ) 186:1338–42.

    Not in our library10.4049/jimmunol.1003081

  47. 47.

    Yokosuka T Takamatsu M Kobayashi-Imanishi W Hashimoto-Tane A Azuma M Saito T. Programmed cell death 1 forms negative costimulatory microclusters that directly inhibit T cell receptor signaling by recruiting phosphatase SHP2. J Exp Med. (2012 ) 209:1201–17.

    Not in our library10.1084/jem.20112741

  48. 48.

    Hui E Cheung J Zhu J Su X Taylor MJ Wallweber HA. T cell costimulatory receptor CD28 is a primary target for PD-1-mediated inhibition. Science. (2017 ) 355:1428–33.

    Not in our library10.1126/science.aaf1292

  49. 49.

    Kamphorst AO Wieland A Nasti T Yang S Zhang R Barber DL. Rescue of exhausted CD8 T cells by PD-1-targeted therapies is CD28-dependent. Science. (2017 ) 355:1423–7.

    Not in our library10.1126/science.aaf0683

  50. 50.

    Curran MA Montalvo W Yagita H Allison JP. PD-1 and CTLA-4 combination blockade expands infiltrating T cells and reduces regulatory T and myeloid cells within B16 melanoma tumors. Proc Natl Acad Sci USA. (2010 ) 107:4275–80.

    Not in our library10.1073/pnas.0915174107

  51. 51.
  52. 52.

    Nishikawa H Sakaguchi S. Regulatory T cells in cancer immunotherapy. Curr Opin Immunol. (2014 ) 27:1–7.

    Not in our library10.1016/j.coi.2013.12.005

  53. 53.

    Sharabi A Tsokos MG Ding Y Malek TR Klatzmann D Tsokos GC. Regulatory T cells in the treatment of disease. Nat Rev Drug Dis. (2018 ) 17:823–44.

    Not in our library10.1038/nrd.2018.148

  54. 54.

    Tanaka A Sakaguchi S. Regulatory T cells in cancer immunotherapy. Cell Res. (2017 ) 27:109–18.

    Not in our library10.1038/cr.2016.151

  55. 55.

    Francisco LM Sage PT Sharpe AH. The PD-1 pathway in tolerance and autoimmunity. Immunol Rev. (2010 ) 236:219–42.

    Not in our library10.1111/j.1600-065x.2010.00923.x

  56. 56.

    Joller N Lozano E Burkett PR Patel B Xiao S Zhu C. Treg cells expressing the coinhibitory molecule TIGIT selectively inhibit proinflammatory Th1 and Th17 cell responses. Immunity. (2014 ) 40:569–81.

    Not in our library10.1016/j.immuni.2014.02.012

  57. 57.

    Kurtulus S Sakuishi K Ngiow SF Joller N Tan DJ Teng MW. TIGIT predominantly regulates the immune response via regulatory T cells. J Clin Invest. (2015 ) 125:4053–62.

    Not in our library10.1172/jci81187

  58. 58.

    Turk MJ Guevara-Patino JA Rizzuto GA Engelhorn ME Sakaguchi S Houghton AN. Concomitant tumor immunity to a poorly immunogenic melanoma is prevented by regulatory T cells. J Exp Med. (2004 ) 200:771–82.

    Not in our library10.1084/jem.20041130

  59. 59.

    Sugiyama D Nishikawa H Maeda Y Nishioka M Tanemura A Katayama I. Anti-CCR4 mAb selectively depletes effector-type FoxP3+CD4+ regulatory T cells, evoking antitumor immune responses in humans. Proc Natl Acad Sci USA. (2013 ) 110:17945–50.

    Not in our library10.1073/pnas.1316796110s

  60. 60.

    Bulliard Y Jolicoeur R Zhang J Dranoff G Wilson NS Brogdon JL. OX40 engagement depletes intratumoral Tregs via activating FcgammaRs, leading to antitumor efficacy. Immunol Cell Biol. (2014 ) 92:475–80.

    Not in our library10.1038/icb.2014.26

  61. 61.

    Quezada SA Peggs KS Simpson TR Shen Y Littman DR Allison JP. Limited tumor infiltration by activated T effector cells restricts the therapeutic activity of regulatory T cell depletion against established melanoma. J Exp Med. (2008 ) 205:2125–38.

    Not in our library10.1084/jem.20080099

  62. 62.

    Simpson TR Li F Montalvo-Ortiz W Sepulveda MA Bergerhoff K Arce F. Fc-dependent depletion of tumor-infiltrating regulatory T cells co-defines the efficacy of anti-CTLA-4 therapy against melanoma. J Exp Med. (2013 ) 210:1695–710.

    Not in our library10.1084/jem.20130579

  63. 63.

    Bulliard Y Jolicoeur R Windman M Rue SM Ettenberg S Knee DA. Activating Fc gamma receptors contribute to the antitumor activities of immunoregulatory receptor-targeting antibodies. J Exp Med. (2013 ) 210:1685–93.

    Not in our library10.1084/jem.20130573

  64. 64.

    Zhao Q Kuang DM Wu Y Xiao X Li XF Li TJ. Activated CD69+ T cells foster immune privilege by regulating IDO expression in tumor-associated macrophages. J Immunol. (2012 ) 188:1117–24.

    Not in our library10.4049/jimmunol.1100164

  65. 65.

    Ye XZ Xu SL Xin YH Yu SC Ping YF Chen L. Tumor-associated microglia/macrophages enhance the invasion of glioma stem-like cells via TGF-beta1 signaling pathway. J Immunol. (2012 ) 189:444–53.

    Not in our library10.4049/jimmunol.1103248

  66. 66.

    Colegio OR Chu NQ Szabo AL Chu T Rhebergen AM Jairam V. Functional polarization of tumour-associated macrophages by tumour-derived lactic acid. Nature. (2014 ) 513:559–63.

    Not in our library10.1038/nature13490

  67. 67.

    Budhwar S Verma P Verma R Rai S Singh K. The Yin and Yang of myeloid derived suppressor cells. Front Immunol. (2018 ) 9:2776.

    Not in our library10.3389/fimmu.2018.02776

  68. 68.

    Veglia F Perego M Gabrilovich D. Myeloid-derived suppressor cells coming of age. Nat Immunol. (2018 ) 19:108–19.

    Not in our library10.1038/s41590-017-0022-x

  69. 69.

    Gabrilovich DI Nagaraj S. Myeloid-derived suppressor cells as regulators of the immune system. Nat Rev Immunol. (2009 ) 9:162–74.

    Not in our library10.1038/nri2506

  70. 70.

    Kalluri R. The biology and function of fibroblasts in cancer. Nat Rev Cancer. (2016 ) 16:582–98.

    Not in our library10.1038/nrc.2016.73

  71. 71.

    Chen X Song E. Turning foes to friends: targeting cancer-associated fibroblasts. Nat Rev Drug Discov. (2018 ) 18:99–115.

    Not in our library10.1038/s41573-018-0004-1

  72. 72.

    Ko SY Barengo N Ladanyi A Lee JS Marini F Lengyel E. HOXA9 promotes ovarian cancer growth by stimulating cancer-associated fibroblasts. J Clin Invest. (2012 ) 122:3603–17.

    Not in our library10.1172/jci62229

  73. 73.
  74. 74.

    Dirat B Bochet L Dabek M Daviaud D Dauvillier S Majed B. Cancer-associated adipocytes exhibit an activated phenotype and contribute to breast cancer invasion. Cancer Res. (2011 ) 71:2455–65.

    Not in our library10.1158/0008-5472.can-10-3323

  75. 75.

    Nieman KM Kenny HA Penicka CV Ladanyi A Buell-Gutbrod R Zillhardt MR. Adipocytes promote ovarian cancer metastasis and provide energy for rapid tumor growth. Nat Med. (2011 ) 17:1498–503.

    Not in our library10.1038/nm.2492

  76. 76.

    Huang CK Chang PH Kuo WH Chen CL Jeng YM Chang KJ. Adipocytes promote malignant growth of breast tumours with monocarboxylate transporter 2 expression via beta-hydroxybutyrate. Nat Commun. (2017 ) 8:14706.

    Not in our library10.1038/ncomms14706

  77. 77.

    Piali L Fichtel A Terpe HJ Imhof BA Gisler RH. Endothelial vascular cell adhesion molecule 1 expression is suppressed by melanoma and carcinoma. J Exp Med. (1995 ) 181:811–6.

    Not in our library10.1084/jem.181.2.811

  78. 78.

    Mulligan JK Rosenzweig SA Young MR. Tumor secretion of VEGF induces endothelial cells to suppress T cell functions through the production of PGE2. J Immunother. (2010 ) 33:126–35.

    Not in our library10.1097/cji.0b013e3181b91c9c

  79. 79.

    Motz GT Santoro SP Wang LP Garrabrant T Lastra RR Hagemann IS. Tumor endothelium FasL establishes a selective immune barrier promoting tolerance in tumors. Nat Med. (2014 ) 20:607–15.

    Not in our library10.1038/nm.3541

  80. 80.

    Ghesquiere B Wong BW Kuchnio A Carmeliet P. Metabolism of stromal and immune cells in health and disease. Nature. (2014 ) 511:167–76.

    Not in our library10.1038/nature13312

  81. 81.

    Card CM Yu SS Swartz MA. Emerging roles of lymphatic endothelium in regulating adaptive immunity. J Clin Invest. (2014 ) 124:943–52.

    Not in our library10.1172/jci73316

  82. 82.

    Humbert M Hugues S Dubrot J. Shaping of peripheral T cell responses by lymphatic endothelial cells. Front Immunol. (2016 ) 7:684.

    Not in our library10.3389/fimmu.2016.00684

  83. 83.

    Mannino MH Zhu Z Xiao H Bai Q Wakefield MR Fang Y. The paradoxical role of IL-10 in immunity and cancer. Cancer Lett. (2015 ) 367:103–7.

    Not in our library10.1016/j.canlet.2015.07.009

  84. 84.

    Moore KW de Waal Malefyt R Coffman RL O'Garra A. Interleukin-10 and the interleukin-10 receptor. Ann Rev Immunol. (2001 ) 19:683–765.

    Not in our library10.1146/annurev.immunol.19.1.683

  85. 85.

    Pestka S Krause CD Sarkar D Walter MR Shi Y Fisher PB. Interleukin-10 and related cytokines and receptors. Ann Rev Immunol. (2004 ) 22:929–79.

    Not in our library10.1146/annurev.immunol.22.012703.104622

  86. 86.

    Drennan S D'Avola A Gao Y Weigel C Chrysostomou E Steele AJ. IL-10 production by CLL cells is enhanced in the anergic IGHV mutated subset and associates with reduced DNA methylation of the IL10 locus. Leukemia. (2017 ) 31:1686–94.

    Not in our library10.1038/leu.2016.356

  87. 87.
  88. 88.

    Fujii S Shimizu K Shimizu T Lotze MT. Interleukin-10 promotes the maintenance of antitumor CD8(+) T-cell effector function in situ. Blood. (2001 ) 98:2143–51.

    Not in our library10.1182/blood.v98.7.2143

  89. 89.

    Sharma S Stolina M Lin Y Gardner B Miller PW Kronenberg M. T cell-derived IL-10 promotes lung cancer growth by suppressing both T cell and APC function. J Immunol. (1999 ) 163:5020–8.

    Not in our library

  90. 90.

    Lamichhane P Karyampudi L Shreeder B Krempski J Bahr D Daum J. IL10 release upon PD-1 blockade sustains immunosuppression in ovarian cancer. Cancer Res. (2017 ) 77:6667–78.

    Not in our library10.1158/0008-5472.can-17-0740

  91. 91.

    Mumm JB Emmerich J Zhang X Chan I Wu L Mauze S. IL-10 elicits IFNgamma-dependent tumor immune surveillance. Cancer Cell. (2011 ) 20:781–96.

    Not in our library10.1016/j.ccr.2011.11.003

  92. 92.

    McNab F Mayer-Barber K Sher A Wack A O'Garra A. Type I interferons in infectious disease. Nat Rev Immunol. (2015 ) 15:87–103.

    Not in our library10.1038/nri3787

  93. 93.

    Curtsinger JM Mescher MF. Inflammatory cytokines as a third signal for T cell activation. Curr Opin Immunol. (2010 ) 22:333–40.

    Not in our library10.1016/j.coi.2010.02.013

  94. 94.

    Teijaro JR Ng C Lee AM Sullivan BM Sheehan KC Welch M. Persistent LCMV infection is controlled by blockade of type I interferon signaling. Science. (2013 ) 340:207–11.

    Not in our library10.1126/science.1235214

  95. 95.

    Terawaki S Chikuma S Shibayama S Hayashi T Yoshida T Okazaki T. IFN-alpha directly promotes programmed cell death-1 transcription and limits the duration of T cell-mediated immunity. J Immunol. (2011 ) 186:2772–9.

    Not in our library10.4049/jimmunol.1003208

  96. 96.

    Uyttenhove C Pilotte L Theate I Stroobant V Colau D Parmentier N. Evidence for a tumoral immune resistance mechanism based on tryptophan degradation by indoleamine 2,3-dioxygenase. Nat Med. (2003 ) 9:1269–74.

    Not in our library10.1038/nm934

  97. 97.

    Sharma MD Baban B Chandler P Hou DY Singh N Yagita H. Plasmacytoid dendritic cells from mouse tumor-draining lymph nodes directly activate mature Tregs via indoleamine 2,3-dioxygenase. J Clin Invest. (2007 ) 117:2570–82.

    Not in our library10.1172/jci31911

  98. 98.

    Spranger S Spaapen RM Zha Y Williams J Meng Y Ha TT. Up-regulation of PD-L1, IDO, and T(regs) in the melanoma tumor microenvironment is driven by CD8(+) T cells. Sci Trans Med. (2013 ) 5:200ra116.

    Not in our library10.1126/scitranslmed.3006504

  99. 99.

    Munn DH Mellor AL. IDO in the tumor microenvironment: inflammation, counter-regulation, and tolerance. Trends Immunol. (2016 ) 37:193–207.

    Not in our library10.1016/j.it.2016.01.002

  100. 100.

    Munn DH Mellor AL. Indoleamine 2,3-dioxygenase and tumor-induced tolerance. J Clin Invest. (2007 ) 117:1147–54.

    Not in our library10.1172/jci31178

  101. 101.

    Holmgaard RB Zamarin D Munn DH Wolchok JD Allison JP. Indoleamine 2,3-dioxygenase is a critical resistance mechanism in antitumor T cell immunotherapy targeting CTLA-4. J Exp Med. (2013 ) 210:1389–402.

    Not in our library10.1084/jem.20130066

  102. 102.

    Raskovalova T Lokshin A Huang X Su Y Mandic M Zarour HM. Inhibition of cytokine production and cytotoxic activity of human antimelanoma specific CD8+ and CD4+ T lymphocytes by adenosine-protein kinase A type I signaling. Cancer Res. (2007 ) 67:5949–56.

    Not in our library10.1158/0008-5472.can-06-4249s

  103. 103.
  104. 104.

    Terme M Pernot S Marcheteau E Sandoval F Benhamouda N Colussi O. VEGFA-VEGFR pathway blockade inhibits tumor-induced regulatory T-cell proliferation in colorectal cancer. Cancer Res. (2013 ) 73:539–49.

    Not in our library10.1158/0008-5472.can-12-2325

  105. 105.

    Gabrilovich DI Chen HL Girgis KR Cunningham HT Meny GM Nadaf S. Production of vascular endothelial growth factor by human tumors inhibits the functional maturation of dendritic cells. Nat Med. (1996 ) 2:1096–103.

    Not in our library10.1038/nm1096-1096

  106. 106.

    Voron T Colussi O Marcheteau E Pernot S Nizard M Pointet AL. VEGF-A modulates expression of inhibitory checkpoints on CD8+ T cells in tumors. J Exp Med. (2015 ) 212:139–48.

    Not in our library10.1084/jem.20140559

  107. 107.

    Tauriello DVF Palomo-Ponce S Stork D Berenguer-Llergo A Badia-Ramentol J Iglesias M. TGFbeta drives immune evasion in genetically reconstituted colon cancer metastasis. Nature. (2018 ) 554:538–43.

    Not in our library10.1038/nature25492.s

  108. 108.

    Mariathasan S Turley SJ Nickles D Castiglioni A Yuen K Wang Y. TGFbeta attenuates tumour response to PD-L1 blockade by contributing to exclusion of T cells. Nature. (2018 ) 554:544–8.

    Not in our library10.1038/nature25501

  109. 109.

    Collison LW Workman CJ Kuo TT Boyd K Wang Y Vignali KM. The inhibitory cytokine IL-35 contributes to regulatory T-cell function. Nature. (2007 ) 450:566–9.

    Not in our library10.1038/nature06306

  110. 110.

    Wang RX Yu CR Dambuza IM Mahdi RM Dolinska MB Sergeev YV. Interleukin-35 induces regulatory B cells that suppress autoimmune disease. Nat Med. (2014 ) 20:633–41.

    Not in our library10.1038/nm.3554

  111. 111.

    Shen P Roch T Lampropoulou V O'Connor RA Stervbo U Hilgenberg E. IL-35-producing B cells are critical regulators of immunity during autoimmune and infectious diseases. Nature. (2014 ) 507:366–70.

    Not in our library10.1038/nature12979

  112. 112.

    Sawant DV Yano H Chikina M Zhang Q Liao M Liu C. Adaptive plasticity of IL-10(+) and IL-35(+) Treg cells cooperatively promotes tumor T cell exhaustion. Nat Immunol. (2019 ) 20:724–35.

    Not in our library10.1038/s41590-019-0346-9

  113. 113.

    Turnis ME Sawant DV Szymczak-Workman AL Andrews LP Delgoffe GM Yano H. Interleukin-35 limits anti-tumor immunity. Immunity. (2016 ) 44:316–29.

    Not in our library10.1016/j.immuni.2016.01.013

  114. 114.

    MacIver NJ Michalek RD Rathmell JC. Metabolic regulation of T lymphocytes. Annl Rev Immunol. (2013 ) 31:259–83.

    Not in our library10.1146/annurev-immunol-032712-095956

  115. 115.

    Chang CH Qiu J O'Sullivan D Buck MD Noguchi T Curtis JD. Metabolic competition in the tumor microenvironment is a driver of cancer progression. Cell. (2015 ) 162:1229–41.

    Not in our library10.1016/j.cell.2015.08.016

  116. 116.

    Ho PC Bihuniak JD Macintyre AN Staron M Liu X Amezquita R. phosphoenolpyruvate is a metabolic checkpoint of anti-tumor T cell responses. Cell. (2015 ) 162:1217–28.

    Not in our library10.1016/j.cell.2015.08.012

  117. 117.

    Zhao E Maj T Kryczek I Li W Wu K Zhao L. Cancer mediates effector T cell dysfunction by targeting microRNAs and EZH2 via glycolysis restriction. Nat Immunol. (2016 ) 17:95–103.

    Not in our library10.1038/ni.3313

  118. 118.

    Frauwirth KA Riley JL Harris MH Parry RV Rathmell JC Plas DR. The CD28 signaling pathway regulates glucose metabolism. Immunity. (2002 ) 16:769–77.

    Not in our library10.1016/s1074-7613(02)00323-0

  119. 119.
  120. 120.

    Lind DS. Arginine and cancer. J Nutr. (2004 ) 134:2837S−41S.

    Not in our library10.1093/jn/134.10.2837s

  121. 121.

    Rodriguez PC Ernstoff MS Hernandez C Atkins M Zabaleta J Sierra R. Arginase I-producing myeloid-derived suppressor cells in renal cell carcinoma are a subpopulation of activated granulocytes. Cancer Res. (2009 ) 69:1553–60.

    Not in our library10.1158/0008-5472.can-08-1921

  122. 122.

    Choi YS Eto D Yang JA Lao C Crotty S. Cutting edge: STAT1 is required for IL-6-mediated Bcl6 induction for early follicular helper cell differentiation. J Immunol. (2013 ) 190:3049–53.

    Not in our library10.4049/jimmunol.1203032

  123. 123.

    Munder M Choi BS Rogers M Kropf P. L-arginine deprivation impairs Leishmania major-specific T-cell responses. Eur J Immunol. (2009 ) 39:2161–72.

    Not in our library10.1002/eji.200839041

  124. 124.

    Carr EL Kelman A Wu GS Gopaul R Senkevitch E Aghvanyan A. Glutamine uptake and metabolism are coordinately regulated by ERK/MAPK during T lymphocyte activation. J Immunol. (2010 ) 185:1037–44.

    Not in our library10.4049/jimmunol.0903586

  125. 125.

    Altman BJ Stine ZE Dang CV From Krebs to clinic: glutamine metabolism to cancer therapy. Nat Rev Cancer. (2016 ) 16:749

    Not in our library10.1038/nrc.2016.114

  126. 126.

    Tanaka K Sasayama T Irino Y Takata K Nagashima H Satoh N. Compensatory glutamine metabolism promotes glioblastoma resistance to mTOR inhibitor treatment. J Clin Invest. (2015 ) 125:1591–602.

    Not in our library10.1172/jci78239

  127. 127.

    Platten M Wick W Van den Eynde BJ. Tryptophan catabolism in cancer: beyond IDO and tryptophan depletion. Cancer Res. (2012 ) 72:5435–40.

    Not in our library10.1158/0008-5472.can-12-0569

  128. 128.

    Julliard W Fechner JH Mezrich JD. The aryl hydrocarbon receptor meets immunology: friend or foe? A little of both. Front Immunol. (2014 ) 5:458.

    Not in our library10.3389/fimmu.2014.00458

  129. 129.

    Xia H Wang W Crespo J Kryczek I Li W Wei S. Suppression of FIP200 and autophagy by tumor-derived lactate promotes naive T cell apoptosis and affects tumor immunity. Sci Immunol. (2017 ) 2:eaan4631.

    Not in our library10.1126/sciimmunol.aan4631

  130. 130.
  131. 131.

    Pilon-Thomas S Kodumudi KN El-Kenawi AE Russell S Weber AM Luddy K. Neutralization of tumor acidity improves antitumor responses to immunotherapy. Cancer Res. (2016 ) 76:1381–90.

    Not in our library10.1158/0008-5472.can-15-1743

  132. 132.

    Doedens AL Phan AT Stradner MH Fujimoto JK Nguyen JV Yang E. Hypoxia-inducible factors enhance the effector responses of CD8(+) T cells to persistent antigen. Nat Immunol. (2013 ) 14:1173–82.

    Not in our library10.1038/ni.2714

  133. 133.
  134. 134.

    Fischer K Hoffmann P Voelkl S Meidenbauer N Ammer J Edinger M. Inhibitory effect of tumor cell-derived lactic acid on human T cells. Blood. (2007 ) 109:3812–9.

    Not in our library10.1182/blood-2006-07-035972

  135. 135.

    Youngblood B Oestreich KJ Ha SJ Duraiswamy J Akondy RS West EE. Chronic virus infection enforces demethylation of the locus that encodes PD-1 in antigen-specific CD8(+) T cells. Immunity. (2011 ) 35:400–12.

    Not in our library10.1016/j.immuni.2011.06.015

  136. 136.

    Youngblood B Noto A Porichis F Akondy RS Ndhlovu ZM Austin JW. Cutting edge: prolonged exposure to HIV reinforces a poised epigenetic program for PD-1 expression in virus-specific CD8 T cells. J Immunol. (2013 ) 191:540–4.

    Not in our library10.4049/jimmunol.1203161

  137. 137.

    Ahn E Youngblood B Lee J Lee J Sarkar S Ahmed R. Demethylation of the PD-1 promoter is imprinted during the effector phase of CD8 T cell exhaustion. J Virol. (2016 ) 90:8934–46.

    Not in our library10.1128/jvi.00798-16s

  138. 138.

    Simon S Vignard V Florenceau L Dreno B Khammari A Lang F. PD-1 expression conditions T cell avidity within an antigen-specific repertoire. Oncoimmunology. (2016 ) 5:e1104448.

    Not in our library10.1080/2162402x.2015.1104448

  139. 139.

    Ghoneim HE Fan Y Moustaki A Abdelsamed HA Dash P Dogra P. De Novo epigenetic programs inhibit PD-1 blockade-mediated T cell rejuvenation. Cell. (2017 ) 170:142–57.

    Not in our library10.1016/j.cell.2017.06.007

  140. 140.

    Sen DR Kaminski J Barnitz RA Kurachi M Gerdemann U Yates KB. The epigenetic landscape of T cell exhaustion. Science. (2016 ) 354:1165–9.

    Not in our library10.1126/science.aae0491

  141. 141.

    Pauken KE Sammons MA Odorizzi PM Manne S Godec J Khan O. Epigenetic stability of exhausted T cells limits durability of reinvigoration by PD-1 blockade. Science. (2016 ) 354:1160–5.

    Not in our library10.1126/science.aaf2807

  142. 142.

    Mognol GP Spreafico R Wong V Scott-Browne JP Togher S Hoffmann A. Exhaustion-associated regulatory regions in CD8(+) tumor-infiltrating T cells. Proc Natl Acad Sci USA. (2017 ) 114:E2776–85.

    Not in our library10.1073/pnas.1620498114

  143. 143.

    Philip M Fairchild L Sun L Horste EL Camara S Shakiba M. Chromatin states define tumour-specific T cell dysfunction and reprogramming. Nature. (2017 ) 545:452–6.

    Not in our library10.1038/nature22367

  144. 144.

    Paley MA Kroy DC Odorizzi PM Johnnidis JB Dolfi DV Barnett BE. Progenitor and terminal subsets of CD8+ T cells cooperate to contain chronic viral infection. Science. (2012 ) 338:1220–5.

    Not in our library10.1126/science.1229620

  145. 145.

    Doering TA Crawford A Angelosanto JM Paley MA Ziegler CG Wherry EJ. Network analysis reveals centrally connected genes and pathways involved in CD8+ T cell exhaustion versus memory. Immunity. (2012 ) 37:1130–44.

    Not in our library10.1016/j.immuni.2012.08.021

  146. 146.

    Intlekofer AM Takemoto N Wherry EJ Longworth SA Northrup JT Palanivel VR. Effector and memory CD8+ T cell fate coupled by T-bet and eomesodermin. Nat Immunol. (2005 ) 6:1236–44.

    Not in our library10.1038/ni1268

  147. 147.

    Pritchard GH Kedl RM Hunter CA. The evolving role of T-bet in resistance to infection. Nat Rev Immunol. (2019 ) 19:398–410.

    Not in our library10.1038/s41577-019-0145-4

  148. 148.

    Pearce EL Mullen AC Martins GA Krawczyk CM Hutchins AS Zediak VP. Control of effector CD8+ T cell function by the transcription factor Eomesodermin. Science. (2003 ) 302:1041–3.

    Not in our library10.1126/science.1090148

  149. 149.

    Banerjee A Gordon SM Intlekofer AM Paley MA Mooney EC Lindsten T. Cutting edge: the transcription factor eomesodermin enables CD8+ T cells to compete for the memory cell niche. J Immunol. (2010 ) 185:4988–92.

    Not in our library10.4049/jimmunol.1002042

  150. 150.

    Staron MM Gray SM Marshall HD Parish IA Chen JH Perry CJ. The transcription factor FoxO1 sustains expression of the inhibitory receptor PD-1 and survival of antiviral CD8(+) T cells during chronic infection. Immunity. (2014 ) 41:802–14.

    Not in our library10.1016/j.immuni.2014.10.013

  151. 151.

    Delpoux A Lai CY Hedrick SM Doedens AL. FOXO1 opposition of CD8(+) T cell effector programming confers early memory properties and phenotypic diversity. Proc Natl Sci USA. (2017 ) 114:E8865–74.

    Not in our library10.1073/pnas.1618916114

  152. 152.

    Shin H Blackburn SD Intlekofer AM Kao C Angelosanto JM Reiner SL. A role for the transcriptional repressor Blimp-1 in CD8(+) T cell exhaustion during chronic viral infection. Immunity. (2009 ) 31:309–20.

    Not in our library10.1016/j.immuni.2009.06.019

  153. 153.

    Man K Gabriel SS Liao Y Gloury R Preston S Henstridge DC. Transcription factor IRF4 promotes CD8(+) T cell exhaustion and limits the development of memory-like T cells during chronic infection. Immunity. (2017 ) 47:1129–41.

    Not in our library10.1016/j.immuni.2017.11.021

  154. 154.

    Kurachi M Barnitz RA Yosef N Odorizzi PM DiIorio MA Lemieux ME. The transcription factor BATF operates as an essential differentiation checkpoint in early effector CD8+ T cells. Nat Immunol. (2014 ) 15:373–83.

    Not in our library10.1038/ni.2834

  155. 155.

    Zhu L Kong Y Zhang J Claxton DF Ehmann WC Rybka WB. Blimp-1 impairs T cell function via upregulation of TIGIT and PD-1 in patients with acute myeloid leukemia. J Hematol Oncol. (2017 ) 10:124.

    Not in our library10.1186/s13045-017-0486-z

  156. 156.

    Haase VH. The VHL/HIF oxygen-sensing pathway and its relevance to kidney disease. Kidney Int. (2006 ) 69:1302–7.

    Not in our library10.1038/sj.ki.5000221

  157. 157.

    Khan O Giles JR McDonald S Manne S Ngiow SF Patel KP. TOX transcriptionally and epigenetically programs CD8(+) T cell exhaustion. Nature. (2019 ) 571:211–8.

    Not in our library10.1038/s41586-019-1325-x

  158. 158.

    Seo H Chen J Gonzalez-Avalos E Samaniego-Castruita D Das A Wang YH. TOX and TOX2 transcription factors cooperate with NR4A transcription factors to impose CD8(+) T cell exhaustion. Proc Natl Acad Sci USA. (2019 ) 116:12410–5.

    Not in our library10.1073/pnas.1905675116

  159. 159.

    Wang X He Q Shen H Xia A Tian W Yu W. TOX promotes the exhaustion of antitumor CD8+ T cells by preventing PD1 degradation in hepatocellular carcinoma. J Hepatol. (2019 ).. [Epub ahead of print].

    Not in our library10.1016/j.jhep.2019.05.015

  160. 160.

    Im SJ Hashimoto M Gerner MY Lee J Kissick HT Burger MC. Defining CD8+ T cells that provide the proliferative burst after PD-1 therapy. Nature. (2016 ) 537:417–21.

    Not in our library10.1038/nature19330

  161. 161.

    Topalian SL Hodi FS Brahmer JR Gettinger SN Smith DC McDermott DF. Safety, activity, and immune correlates of anti-PD-1 antibody in cancer. N Engl J Med. (2012 ) 366:2443–54.

    Not in our library10.1056/nejmoa1200690

  162. 162.

    Hamid O Robert C Daud A Hodi FS Hwu WJ Kefford R. Safety and tumor responses with lambrolizumab (anti-PD-1) in melanoma. N Engl J Med. (2013 ) 369:134–44.

    Not in our library10.1056/nejmoa1305133

  163. 163.

    Ribas A Wolchok JD. Cancer immunotherapy using checkpoint blockade. Science. (2018 ) 359:1350–5.

    Not in our library10.1126/science.aar4060

  164. 164.

    Im A Pavletic SZ. Immunotherapy in hematologic malignancies: past, present, and future. J Hematol Oncol. (2017 ) 10:94.

    Not in our library10.1186/s13045-017-0453-8s

  165. 165.

    Krummel MF Allison JP. CD28 and CTLA-4 have opposing effects on the response of T cells to stimulation. J Exp Med. (1995 ) 182:459–65.

    Not in our library10.1084/jem.182.2.459

  166. 166.

    Sharpe AH Pauken KE. The diverse functions of the PD1 inhibitory pathway. Nat Rev Immunol. (2018 ) 18:153–67.

    Not in our library10.1038/nri.2017.108

  167. 167.

    Hodi FS O'Day SJ McDermott DF Weber RW Sosman JA Haanen JB. Improved survival with ipilimumab in patients with metastatic melanoma. N Engl J Med. (2010 ) 363:711–23.

    Not in our library10.1056/nejmoa1003466

  168. 168.

    Robert C Thomas L Bondarenko I O'Day S Weber J Garbe C. Ipilimumab plus dacarbazine for previously untreated metastatic melanoma. N Engl J Med. (2011 ) 364:2517–26.

    Not in our library10.1056/nejmoa1104621s

  169. 169.

    Kvistborg P Philips D Kelderman S Hageman L Ottensmeier C Joseph-Pietras D. Anti-CTLA-4 therapy broadens the melanoma-reactive CD8+ T cell response. Sci Trans Med. (2014 ) 6:254ra128.

    Not in our library10.1126/scitranslmed.3008918

  170. 170.

    Ansell SM Lesokhin AM Borrello I Halwani A Scott EC Gutierrez M PD-1 blockade with nivolumab in relapsed or refractory Hodgkin's lymphoma. N Engl J Med. (2015 ) 372:311–9.

    Not in our library10.1056/nejmoa1411087

  171. 171.

    Nghiem PT Bhatia S Lipson EJ Kudchadkar RR Miller NJ Annamalai L. PD-1 Blockade with pembrolizumab in advanced merkel-cell carcinoma. N Engl J Med. (2016 ) 374:2542–52.

    Not in our library10.1056/nejmoa1603702

  172. 172.

    Le DT Durham JN Smith KN Wang H Bartlett BR Aulakh LK. Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade. Science. (2017 ) 357:409–13.

    Not in our library10.1126/science.aan6733

  173. 173.

    Eroglu Z Zaretsky JM Hu-Lieskovan S Kim DW Algazi A Johnson DB. High response rate to PD-1 blockade in desmoplastic melanomas. Nature. (2018 ) 553:347–50.

    Not in our library10.1038/nature25187

  174. 174.
  175. 175.

    Xia AL Xu Y Lu XJ. Cancer immunotherapy: challenges and clinical applications. J Med Genet. (2019 ) 56:1–3.

    Not in our library10.1136/jmedgenet-2018-105852

  176. 176.

    Wolchok JD Kluger H Callahan MK Postow MA Rizvi NA Lesokhin AM. Nivolumab plus ipilimumab in advanced melanoma. N Engl J Med. (2013 ) 369:122–33.

    Not in our library10.1056/nejmoa1302369

  177. 177.

    Larkin J Chiarion-Sileni V Gonzalez R Grob JJ Cowey CL Lao CD Combined nivolumab and Ipilimumab or monotherapy in untreated melanoma. N Engl J Med. (2015 ) 373:23–34.

    Not in our library10.1056/nejmoa1504030

  178. 178.

    Lu X Yang L Yao D Wu X Li J Liu X. Tumor antigen-specific CD8(+) T cells are negatively regulated by PD-1 and Tim-3 in human gastric cancer. Cell Immunol. (2017 ) 313:43–51.

    Not in our library10.1016/j.cellimm.2017.01.001

  179. 179.

    Matsuzaki J Gnjatic S Mhawech-Fauceglia P Beck A Miller A Tsuji T. Tumor-infiltrating NY-ESO-1-specific CD8+ T cells are negatively regulated by LAG-3 and PD-1 in human ovarian cancer. Proc Natl Acad Sci USA. (2010 ) 107:7875–80.

    Not in our library10.1073/pnas.1003345107

  180. 180.

    Pollok KE Kim YJ Zhou Z Hurtado J Kim KK Pickard RT. Inducible T cell antigen 4-1BB. Analysis of expression and function. J Immunol. (1993 ) 150:771–81.

    Not in our library

  181. 181.

    Wei H Zhao L Li W Fan K Qian W Hou S. Combinatorial PD-1 blockade and CD137 activation has therapeutic efficacy in murine cancer models and synergizes with cisplatin. PLoS ONE. (2013 ) 8:e84927.

    Not in our library10.1371/journal.pone.0084927

  182. 182.

    Chen S Lee LF Fisher TS Jessen B Elliott M Evering W. Combination of 4-1BB agonist and PD-1 antagonist promotes antitumor effector/memory CD8 T cells in a poorly immunogenic tumor model. Cancer Immunol Res. (2015 ) 3:149–60.

    Not in our library10.1158/2326-6066.cir-14-0118

  183. 183.

    Croft M. Control of immunity by the TNFR-related molecule OX40 (CD134). Ann Rev Immunol. (2010 ) 28:57–78.

    Not in our library10.1146/annurev-immunol-030409-101243

  184. 184.

    Kjaergaard J Tanaka J Kim JA Rothchild K Weinberg A Shu S. Therapeutic efficacy of OX-40 receptor antibody depends on tumor immunogenicity and anatomic site of tumor growth. Cancer Res. (2000 ) 60:5514–21.

    Not in our library

  185. 185.

    Weinberg AD Rivera MM Prell R Morris A Ramstad T Vetto JT. Engagement of the OX-40 receptor in vivo enhances antitumor immunity. J Immunol. (2000 ) 164:2160–S9.

    Not in our library10.4049/jimmunol.164.4.2160

  186. 186.

    Shrimali RK Ahmad S Verma V Zeng P Ananth S Gaur P. Concurrent PD-1 blockade negates the effects of OX40 agonist antibody in combination immunotherapy through inducing T-cell apoptosis. Cancer Immunol. Res. (2017 ) 5:755–66.

    Not in our library10.1158/2326-6066.cir-17-0292

  187. 187.

    Wu X Li J Connolly EM Liao X Ouyang J Giobbie-Hurder A. Combined anti-VEGF and anti-CTLA-4 therapy elicits humoral immunity to Galectin-1 which is associated with favorable clinical outcomes. Cancer Immunol Res. (2017 ) 5:446–54.

    Not in our library10.1158/2326-6066.cir-16-0385

  188. 188.

    Zhang Y Kurupati R Liu L Zhou XY Zhang G Hudaihed A. Enhancing CD8(+) T cell fatty acid catabolism within a metabolically challenging tumor microenvironment increases the efficacy of melanoma immunotherapy. Cancer Cell. (2017 ) 32:377–91.

    Not in our library10.1016/j.ccell.2017.08.004

  189. 189.

    Newick K O'Brien S Moon E Albelda SM. CAR T cell therapy for solid tumors. Annu Rev Med. (2017 ) 68:139–52.

    Not in our library10.1146/annurev-med-062315-120245

  190. 190.

    Garber K. Driving T-cell immunotherapy to solid tumors. Nat Biotechnol. (2018 ) 36:215–9.

    Not in our library10.1038/nbt.4090

  191. 191.

    Wei G Ding L Wang J Hu Y Huang H. Advances of CD19-directed chimeric antigen receptor-modified T cells in refractory/relapsed acute lymphoblastic leukemia. Exp Hematol Oncol. (2017 ) 6:10.

    Not in our library10.1186/s40164-017-0070-9

  192. 192.

    Cao J Wang G Cheng H Wei C Qi K Sang W. Potent anti-leukemia activities of humanized CD19-targeted chimeric antigen receptor T (CAR-T) cells in patients with relapsed/refractory acute lymphoblastic leukemia. Am J Hematol. (2018 ) 93:851–8.

    Not in our library10.1002/ajh.25108

  193. 193.

    Fraietta JA Lacey SF Orlando EJ Pruteanu-Malinici I Gohil M Lundh S. Determinants of response and resistance to CD19 chimeric antigen receptor (CAR) T cell therapy of chronic lymphocytic leukemia. Nat Med. (2018 ) 24:563–71.

    Not in our library10.1038/s41591-018-0010-1

  194. 194.

    Zolov SN Rietberg SP Bonifant CL. Programmed cell death protein 1 activation preferentially inhibits CD28.CAR-T cells. Cytotherapy. (2018 ) 20:1259–66.

    Not in our library10.1016/j.jcyt.2018.07.005

  195. 195.

    Rafiq S Yeku OO Jackson HJ Purdon TJ van Leeuwen DG Drakes DJ. Targeted delivery of a PD-1-blocking scFv by CAR-T cells enhances anti-tumor efficacy in vivo. Nat Biotechnol. (2018 ) 36:847–56.

    Not in our library10.1038/nbt.4195

  196. 196.
  197. 197.

    Zhang Y Zhang X Cheng C Mu W Liu X Li N. CRISPR-Cas9 mediated LAG-3 disruption in CAR-T cells. Front Med. (2017 ) 11:554–62.

    Not in our library10.1007/s11684-017-0543-6

  198. 198.

    Hu B Zou Y Zhang L Tang J Niedermann G Firat E. Nucleofection with plasmid DNA for CRISPR/Cas9-mediated inactivation of programmed cell death protein 1 in CD133-specific CAR T cells. Hum Gene Ther. (2018 ) 30: 446–458.

    Not in our library10.1089/hum.2017.234

  199. 199.

    Li S Siriwon N Zhang X Yang S Jin T He F. Enhanced cancer immunotherapy by chimeric antigen receptor-modified T cells engineered to secrete checkpoint inhibitors. Clin Cancer Res. (2017 ) 23:6982–92.

    Not in our library10.1158/1078-0432.ccr-17-0867

  200. 200.
  201. 201.
  202. 202.
  203. 203.

    Beavis PA Henderson MA Giuffrida L Mills JK Sek K Cross RS. Targeting the adenosine 2A receptor enhances chimeric antigen receptor T cell efficacy. J Clin Invest. (2017 ) 127:929–41.

    Not in our library10.1172/jci89455

  204. 204.

    Wu X Giobbie-Hurder A Connolly EM Li J Liao X Severgnini M. Anti-CTLA-4 based therapy elicits humoral immunity to galectin-3 in patients with metastatic melanoma. Oncoimmunology. (2018 ) 7:e1440930.

    Not in our library10.1080/2162402x.2018.1440930

  205. 205.

    Chinnasamy D Yu Z Kerkar SP Zhang L Morgan RA Restifo NP. Local delivery of interleukin-12 using T cells targeting VEGF receptor-2 eradicates multiple vascularized tumors in mice. Clin Cancer Res. (2012 ) 18:1672–83.

    Not in our library10.1158/1078-0432.ccr-11-3050

  206. 206.

    Zaretsky JM Garcia-Diaz A Shin DS Escuin-Ordinas H Hugo W Hu-Lieskovan S. Mutations associated with acquired resistance to PD-1 blockade in melanoma. N Engl J Med. (2016 ) 375:819–29.

    Not in our library10.1056/nejmoa1604958

  207. 207.

    Patel SJ Sanjana NE Kishton RJ Eidizadeh A Vodnala SK Cam M. Identification of essential genes for cancer immunotherapy. Nature. (2017 ) 548:537–42.

    Not in our library10.1038/nature23477

  208. 208.

    Hugo W Shi H Sun L Piva M Song C Kong X. Non-genomic and immune evolution of melanoma acquiring MAPKi resistance. Cell. (2015 ) 162:1271–85.

    Not in our library10.1016/j.cell.2015.07.061

  209. 209.

    Ma C Cheung AF Chodon T Koya RC Wu Z Ng C. Multifunctional T-cell analyses to study response and progression in adoptive cell transfer immunotherapy. Cancer Discov. (2013 ) 3:418–29.

    Not in our library10.1158/2159-8290.cd-12-0383

  210. 210.
  211. 211.

    Shayan G Srivastava R Li J Schmitt N Kane LP Ferris RL. Adaptive resistance to anti-PD1 therapy by Tim-3 upregulation is mediated by the PI3K-Akt pathway in head and neck cancer. Oncoimmunology. (2017 ) 6:e1261779.

    Not in our library10.1080/2162402x.2016.1261779

  212. 212.

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