Poorer survival outcomes in patients with multiple versus single primary melanoma.

BACKGROUND: Given equivocal results related to overall survival (OS) for patients with multiple primary melanomas (MPMs) compared with those with single primary melanomas (SPMs) in previous reports, the authors sought to determine whether OS differs between these 2 cohorts in their center using their UPCI-96-99 database. Secondary aims were to assess the differences in recurrence-free survival (RFS). In a subset of patients, transcriptomic profiling of peripheral blood mononuclear cells (PBMCs) was performed to assess disease-associated genes of interest. METHODS: This retrospective case-controlled study included patients with MPMs and age-, sex-, and stage-matched controls with SPMs at a 1:1 ratio. Cox regression models were used to evaluate the effect of the presence of MPMs on death and recurrence. NanoString PanCancer Immune Profiling was used to assess peripheral blood immune status in patients. RESULTS: In total, 320 patients were evaluated. The mean patient age was 47 years; 43.8% were male. Patients with MPMs had worse RFS and OS (P = .023 and P = .0019, respectively). The presence of MPMs was associated with an increased risk of death (hazard ratio [HR], 4.52, P = .0006), and increased risk of disease recurrence (HR, 2.17; P = .004) after adjusting for age, sex, and stage. The degree of tumor-infiltrating lymphocytes (TILs) was different between the first melanoma of MPMs and SPMs. Expression of CXCL6 and FOXJ1 was increased in PBMCs isolated from patients with MPMs. CONCLUSIONS: Patients with MPMs had worse RFS and OS compared with patients with SPMs. Immunologic differences were also observed, including TIL content and expression of CXCL6/FOXJ1 in PBMCs of patients with MPMs, which warrant further investigation.

Actin-binding protein profilin1 promotes aggressiveness of clear-cell renal cell carcinoma cells.

Clear-cell renal cell carcinoma (ccRCC), the most common subtype of renal cancer, has a poor clinical outcome. A hallmark of ccRCC is genetic loss-of-function of VHL (von Hippel-Lindau) that leads to a highly vascularized tumor microenvironment. Although many ccRCC patients initially respond to antiangiogenic therapies, virtually all develop progressive, drug-refractory disease. Given the role of dysregulated expressions of cytoskeletal and cytoskeleton-regulatory proteins in tumor progression, we performed analyses of The Cancer Genome Atlas (TCGA) transcriptome data for different classes of actin-binding proteins to demonstrate that increased mRNA expression of profilin1 (Pfn1), Arp3, cofilin1, Ena/VASP, and CapZ, is an indicator of poor prognosis in ccRCC. Focusing further on Pfn1, we performed immunohistochemistry-based classification of Pfn1 staining in tissue microarrays, which indicated Pfn1 positivity in both tumor and stromal cells; however, the vast majority of ccRCC tumors tend to be Pfn1-positive selectively in stromal cells only. This finding is further supported by evidence for dramatic transcriptional up-regulation of Pfn1 in tumor-associated vascular endothelial cells in the clinical specimens of ccRCC. In vitro studies support the importance of Pfn1 in proliferation and migration of RCC cells and in soluble Pfn1's involvement in vascular endothelial cell tumor cell cross-talk. Furthermore, proof-of-concept studies demonstrate that treatment with a novel computationally designed Pfn1-actin interaction inhibitor identified herein reduces proliferation and migration of RCC cells in vitro and RCC tumor growth in vivo Based on these findings, we propose a potentiating role for Pfn1 in promoting tumor cell aggressiveness in the setting of ccRCC.

Epigenetic modulation of antitumor immunity for improved cancer immunotherapy.

Epigenetic mechanisms play vital roles not only in cancer initiation and progression, but also in the activation, differentiation and effector function(s) of immune cells. In this review, we summarize current literature related to epigenomic dynamics in immune cells impacting immune cell fate and functionality, and the immunogenicity of cancer cells. Some important immune-associated genes, such as granzyme B, IFN-γ, IL-2, IL-12, FoxP3 and STING, are regulated via epigenetic mechanisms in immune or/and cancer cells, as are immune checkpoint molecules (PD-1, CTLA-4, TIM-3, LAG-3, TIGIT) expressed by immune cells and tumor-associated stromal cells. Thus, therapeutic strategies implementing epigenetic modulating drugs are expected to significantly impact the tumor microenvironment (TME) by promoting transcriptional and metabolic reprogramming in local immune cell populations, resulting in inhibition of immunosuppressive cells (MDSCs and Treg) and the activation of anti-tumor T effector cells, professional antigen presenting cells (APC), as well as cancer cells which can serve as non-professional APC. In the latter instance, epigenetic modulating agents may coordinately promote tumor immunogenicity by inducing de novo expression of transcriptionally repressed tumor-associated antigens, increasing expression of neoantigens and MHC processing/presentation machinery, and activating tumor immunogenic cell death (ICD). ICD provides a rich source of immunogens for anti-tumor T cell cross-priming and sensitizing cancer cells to interventional immunotherapy. In this way, epigenetic modulators may be envisioned as effective components in combination immunotherapy approaches capable of mediating superior therapeutic efficacy.

CD40 Cross-Linking Induces Migration of Renal Tumor Cell through Nuclear Factor of Activated T Cells (NFAT) Activation.

CD40 crosslinking plays an important role in regulating cell migration, adhesion and proliferation in renal cell carcinoma (RCC). CD40/CD40L interaction on RCC cells activates different intracellular pathways but the molecular mechanisms leading to cell scattering are not yet clearly defined. Aim of our study was to investigate the main intracellular pathways activated by CD40 ligation and their specific involvement in RCC cell migration. CD40 ligation increased the phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun NH (2)-terminal kinase (JNK) and p38 MAPK. Furthermore, CD40 crosslinking activated different transcriptional factors on RCC cell lines: AP-1, NFkB and some members of the Nuclear Factor of Activated T cells (NFAT) family. Interestingly, the specific inhibition of NFAT factors by cyclosporine A, completely blocked RCC cell motility induced by CD40 ligation. In tumor tissue, we observed a higher expression of NFAT factors and in particular an increased activation and nuclear migration of NFATc4 on RCC tumor tissues belonging to patients that developed metastases when compared to those who did not. Moreover, CD40-CD40L interaction induced a cytoskeleton reorganization and increased the expression of integrin ß1 on RCC cell lines, and this effect was reversed by cyclosporine A and NFAT inhibition. These data suggest that CD40 ligation induces the activation of different intracellular signaling pathways, in particular the NFATs factors, that could represent a potential therapeutic target in the setting of patients with metastatic RCC.

Tumor-derived exosomes promote carcinogenesis of murine oral squamous cell carcinoma.

Circulating tumor-derived exosomes (TEX) interact with a variety of cells in cancer-bearing hosts, leading to cellular reprogramming which promotes disease progression. To study TEX effects on the development of solid tumors, immunosuppressive exosomes carrying PD-L1 and FasL were isolated from supernatants of murine or human HNSCC cell lines. TEX were delivered (IV) to immunocompetent C57BL/6 mice bearing premalignant oral/esophageal lesions induced by the carcinogen, 4-nitroquinoline 1-oxide (4NQO). Progression of the premalignant oropharyngeal lesions to malignant tumors was monitored. A single TEX injection increased the number of developing tumors (6.2 versus 3.2 in control mice injected with phosphate-buffered saline; P < 0.0002) and overall tumor burden per mouse (P < 0.037). The numbers of CD4+ and CD8+ T lymphocytes infiltrating the developing tumors were coordinately reduced (P < 0.01) in mice injected with SCCVII-derived TEX relative to controls. Notably, TEX isolated from mouse or human tumors had similar effects on tumor development and immune cells. A single IV injection of TEX was sufficient to condition mice harboring premalignant OSCC lesions for accelerated tumor progression in concert with reduced immune cell migration to the tumor.

IL-36 Signaling in the Tumor Microenvironment.

The ability of the immune system to prevent or control the growth of tumor cells is critically dependent on inflammatory processes that lead to the activation, expansion, and recruitment of antitumor effector cells into the tumor microenvironment (TME). These processes are orchestrated by soluble cytokines produced in tissues that alarm local immune surveillance cells (such as dendritic cells, DCs) to mobilize protective antitumor immune populations (B cells, T cells). The interleukin (IL)-36 family of pro-inflammatory cytokines plays an important role in multiple disease processes, ranging from an instigator of autoimmune psoriasis to an initiator of therapeutic immune responses against tumor cells. This chapter will focus on the biologic role of immunomodulatory IL-36 family cytokines in the cancer setting and their potential utility in the design of effective interventional therapies. (127 words).

Association of IL-36γ with tertiary lymphoid structures and inflammatory immune infiltrates in human colorectal cancer.

IL-1 family cytokines play a dual role in the gut, with different family members contributing either protective or pathogenic effects. IL-36γ is an IL-1 family cytokine involved in polarizing type-1 immune responses. However, its function in the gut, including in colorectal cancer pathogenesis, is not well appreciated. In a murine model of colon carcinoma, IL-36γ controls tertiary lymphoid structure formation and promotes a type-1 immune response concurrently with a decrease in expression of immune checkpoint molecules in the tumor microenvironment. Here, we demonstrate that IL-36γ plays a similar role in driving a pro-inflammatory phenotype in human colorectal cancer. We analyzed a cohort of 33 primary colorectal carcinoma tumors using imaging, flow cytometry, and transcriptomics to determine the pattern and role of IL-36γ expression in this disease. In the colorectal tumor microenvironment, we observed IL-36γ to be predominantly expressed by M1 macrophages and cells of the vasculature, including smooth muscle cells and high endothelial venules. This pattern of IL-36γ expression is associated with a CD4+ central memory T cell infiltrate and an increased density of B cells in tertiary lymphoid structures, as well as with markers of fibrosis. Conversely, expression of the antagonist to IL-36 signaling, IL-1F5, was associated with intratumoral expression of checkpoint molecules, including PD-1, PD-L1, and CTLA4, which can suppress the immune response. These data support a role for IL-36γ in the physiologic immune response to colorectal cancer by sustaining inflammation within the tumor microenvironment.

Impact of combination immunochemotherapies on progression of 4NQO-induced murine oral squamous cell carcinoma.

Advanced oral squamous cell carcinomas (OSCC) have limited therapeutic options. Although immune therapies are emerging as a potentially effective alternative or adjunct to chemotherapies, the therapeutic efficacy of combination immune chemotherapies has yet to be determined. Using a 4-nitroquinolone-N-oxide (4NQO) orthotopic model of OSCC in immunocompetent mice, we evaluated the therapeutic efficacy of single- and combined-agent treatment with a poly-epitope tumor peptide vaccine, cisplatin and/or an A2AR inhibitor, ZM241385. The monotherapies or their combinations resulted in a partial inhibition of tumor growth and, in some cases, a significant but transient upregulation of systemic anti-tumor CD8+ T cell responses. These responses eroded in the face of expanding immunoregulatory cell populations at later stages of tumor progression. Our findings support the need for the further development of combinatorial therapeutic approaches that could more effectively silence dominant immune inhibitory pathways operating in OSCC and provide novel, more beneficial treatment options for this tumor.

Genetic vaccines to potentiate the effective CD103+ dendritic cell-mediated cross-priming of antitumor immunity.

The development of effective cancer vaccines remains an urgent, but as yet unmet, clinical need. This deficiency is in part due to an incomplete understanding of how to best invoke dendritic cells (DC) that are crucial for the induction of tumor-specific CD8(+) T cells capable of mediating durable protective immunity. In this regard, elevated expression of the transcription factor X box-binding protein 1 (XBP1) in DC appears to play a decisive role in promoting the ability of DC to cross-present Ags to CD8(+) T cells in the therapeutic setting. Delivery of DNA vaccines encoding XBP1 and tumor Ag to skin DC resulted in increased IFN-α production by plasmacytoid DC (pDC) from skin/tumor draining lymph nodes and the cross-priming of Ag-specific CD8(+) T cell responses associated with therapeutic benefit. Antitumor protection was dependent on cross-presenting Batf3(+) DC, pDC, and CD8(+) T cells. CD103(+) DC from the skin/tumor draining lymph nodes of the immunized mice appeared responsible for activation of Ag-specific naive CD8(+) T cells, but were dependent on pDC for optimal effectiveness. Similarly, human XBP1 improved the capacity of human blood- and skin-derived DC to activate human T cells. These data support an important intrinsic role for XBP1 in DC for effective cross-priming and orchestration of Batf3(+) DC-pDC interactions, thereby enabling effective vaccine induction of protective antitumor immunity.

Immunotherapeutic Targeting of Tumor-Associated Blood Vessels.

Pathological angiogenesis occurs during tumor progression and leads in the formation of an abnormal vasculature in the tumor microenvironment (TME). The tumor vasculature is disorganized, tortuous and leaky, resulting in high interstitial pressure and hypoxia in the TME, all of which are events that support tumor growth and survival. Given the sustaining role of the tumor vasculature, it has become an increasingly attractive target for the development of anti-cancer therapies. Antibodies, tyrosine kinase inhibitors and cancer vaccines that target pro-angiogenic factors, angiogenesis-associated receptors or tumor blood vessel-associated antigens continue to be developed and tested for therapeutic efficacy. Preferred anti-angiogenic protocols include those that "normalize" the tumor-associated vasculature which reduce hypoxia and improve tumor blood perfusion, resulting in tumor cell apoptosis, decreased immunosuppression, and enhanced effector immune cell infiltration/tumoricidal action within the TME.

Tumor-associated mesenchymal stem cells inhibit naïve T cell expansion by blocking cysteine export from dendritic cells.

Mesenchymal stem cells (MSCs) represent an important cellular constituent of the tumor microenvironment, which along with tumor cells themselves, serve to regulate protective immune responses in support of progressive disease. We report that tumor MSCs prevent the ability of dendritic cells (DC) to promote naïve CD4(+) and CD8(+) T cell expansion, interferon gamma secretion and cytotoxicity against tumor cells, which are critical to immune-mediated tumor eradication. Notably, tumor MSCs fail to prevent DC-mediated early T cell activation events or the ability of responder T cells to produce IL-2. The immunoregulatory activity of tumor MSCs is IL-10- and STAT3-dependent, with STAT3 repressing DC expression of cystathionase, a critical enzyme that converts methionine-to-cysteine. Under cysteine-deficient priming conditions, naïve T cells exhibit defective cellular metabolism and proliferation. Bioinformatics analyses as well as in vitro observations suggest that STAT3 may directly bind to a GAS-like motif within the cystathionase promoter (-269 to -261) leading to IL-10-STAT3 mediated repression of cystathionase gene transcription. Our collective results provide evidence for a novel mechanism of tumor MSC-mediated T cell inhibition within tumor microenvironment.

miR-29b and miR-198 overexpression in CD8+ T cells of renal cell carcinoma patients down-modulates JAK3 and MCL-1 leading to immune dysfunction.

BACKGROUND: Mammalian microRNAs (miR) regulate the expression of genes relevant for the development of adaptive and innate immunity against cancer. Since T cell dysfunction has previously been reported in patients with renal cell carcinoma (RCC; clear cell type), we aimed to analyze these immune cells for genetic and protein differences when compared to normal donor T cells freshly after isolation and 35 days after in vitro stimulation (IVS) with HLA-matched RCC tumor cells. METHODS: We investigated gene expression profiles of tumor-reactive CD8(+) T cells obtained from RCC patient and compared with their HLA-matched healthy sibling donors using a microarray approach. In addition, miRNAs analysis was performed in a validation cohort of peripheral blood CD8(+) T cells from 25 RCC patients compared to 15 healthy volunteers. RESULTS: We observed that CD8(+) T cells from RCC patients expressed reduced levels of anti-apoptotic and proliferation-associated gene products when compared with normal donor T cells both pre- and post-IVS. In particular, JAK3 and MCL-1 were down-regulated in patient CD8(+) T cells versus their normal counterparts, likely due to defective suppressor activity of miR-29b and miR-198 in RCC CD8(+) T cells. Indeed, specific inhibition of miR-29b or miR-198 in peripheral blood mononuclear cells (PBMCs) isolated from RCC patients, resulted in the up-regulation of JAK3 and MCL-1 proteins and significant improvement of cell survival in vitro. CONCLUSIONS: Our results suggest that miR-29b and miR-198 dysregulation in RCC patient CD8(+) T cells is associated with dysfunctional immunity and foreshadow the development of miR-targeted therapeutics to correct such T cell defects in vivo.

Neurokinin-1 receptor agonists bias therapeutic dendritic cells to induce type 1 immunity by licensing host dendritic cells to produce IL-12.

Substance-P and hemokinin-1 are proinflammatory neuropeptides with potential to promote type 1 immunity through agonistic binding to neurokinin-1 receptor (NK1R). Dendritic cells (DCs) are professional antigen-presenting cells that initiate and regulate the outcome of innate and adaptive immune responses. Immunostimulatory DCs are highly desired for the development of positive immunization techniques. DCs express functional NK1R; however, regardless of their potential DC-stimulatory function, the ability of NK1R agonists to promote immunostimulatory DCs remains unexplored. Here, we demonstrate that NK1R signaling activates therapeutic DCs capable of biasing type 1 immunity by inhibition of interleukin-10 (IL-10) synthesis and secretion, without affecting their low levels of IL-12 production. The potent type 1 effector immune response observed following cutaneous administration of NK1R-signaled DCs required their homing in skin-draining lymph nodes (sDLNs) where they induced inflammation and licensed endogenous-conventional sDLN-resident and -recruited inflammatory DCs to secrete IL-12. Our data demonstrate that NK1R signaling promotes immunostimulatory DCs, and provide relevant insight into the mechanisms used by neuromediators to regulate innate and adaptive immune responses.

Tumor-derived vascular pericytes anergize Th cells.

Immune evasion within the tumor microenvironment supports malignant growth and is also a major obstacle for successful immunotherapy. Multiple cellular components and soluble factors coordinate to disrupt protective immune responses. Although stromal cells are well-known for their parenchymal supportive roles in cancer establishment and progression, we demonstrate for the first time, to our knowledge, that tumor-derived vascular pericytes negatively influence CD4(+) T cell activation and proliferation, and promote anergy in recall response to Ag by CD4(+)CD44(+) T cells via regulator of G protein signaling 5- and IL-6-dependent pathways. Our data support a new specific role for tumor-derived pericytes in the immune evasion paradigm within the tumor microenvironment and suggest the targeting of these cell populations in the context of successful immunotherapeutics for the treatment of cancer.

Vaccines targeting tumor blood vessel antigens promote CD8(+) T cell-dependent tumor eradication or dormancy in HLA-A2 transgenic mice.

We have recently shown that effective cytokine gene therapy of solid tumors in HLA-A2 transgenic (HHD) mice lacking murine MHC class I molecule expression results in the generation of HLA-A2-restricted CD8(+) T effector cells selectively recognizing tumor blood vessel-associated pericytes and/or vascular endothelial cells. Using an HHD model in which HLA-A2(neg) tumor (MC38 colon carcinoma or B16 melanoma) cells are not recognized by the CD8(+) T cell repertoire, we now show that vaccines on the basis of tumor-associated blood vessel Ags (TBVA) elicit protective Tc1-dependent immunity capable of mediating tumor regression or extending overall survival. Vaccine efficacy was not observed if (HLA-A2(neg)) wild-type C57BL/6 mice were instead used as recipient animals. In the HHD model, effective vaccination resulted in profound infiltration of tumor lesions by CD8(+) (but not CD4(+)) T cells, in a coordinate reduction of CD31(+) blood vessels in the tumor microenvironment, and in the "spreading" of CD8(+) T cell responses to alternate TBVA that were not intrinsic to the vaccine. Protective Tc1-mediated immunity was durable and directly recognized pericytes and/or vascular endothelial cells flow-sorted from tumor tissue but not from tumor-uninvolved normal kidneys harvested from these same animals. Strikingly, the depletion of CD8(+), but not CD4(+), T cells at late time points after effective therapy frequently resulted in the recurrence of disease at the site of the regressed primary lesion. This suggests that the vaccine-induced anti-TBVA T cell repertoire can mediate the clinically preferred outcomes of either effectively eradicating tumors or policing a state of (occult) tumor dormancy.

DLK1: a novel target for immunotherapeutic remodeling of the tumor blood vasculature.

Tumor blood vessels are frequently inefficient in their design and function, leading to high interstitial fluid pressure, hypoxia, and acidosis in the tumor microenvironment (TME), rendering tumors refractory to the delivery of chemotherapeutic agents and immune effector cells. Here we identified the NOTCH antagonist delta-like 1 homologue (DLK1) as a vascular pericyte-associated antigen expressed in renal cell carcinomas (RCC), but not in normal kidney tissues in mice and humans. Vaccination of mice bearing established RCC against DLK1 led to immune-mediated elimination of DLK1(+) pericytes and to blood vessel normalization (i.e., decreased vascular permeability and intratumoral hypoxia) in the TME, in association with tumor growth suppression. After therapeutic vaccination, tumors displayed increased prevalence of activated VCAM1(+)CD31(+) vascular endothelial cells (VECs) and CXCL10, a type-1 T cell recruiting chemokine, in concert with increased levels of type-1 CD8(+) tumor-infiltrating lymphocytes (TIL). Vaccination against DLK1 also yielded (i) dramatic reductions in Jarid1B(+), CD133(+), and CD44(+) (hypoxia-responsive) stromal cell populations, (ii) enhanced tumor cell apoptosis, and (iii) increased NOTCH signaling in the TME. Coadministration of a γ-secretase inhibitor (N-[N-(3,5-Difluorophenacetyl-l-alanyl)]-(S)-phenylglycine t-butyl ester (DAPT)) that interferes with canonical NOTCH signaling resulted in the partial loss of therapeutic benefits associated with lentivirus encoding full-length murine (lvDLK1)-based vaccination.

Antagonism of regulatory ISGs enhances the anti-melanoma efficacy of STING agonists.

Background: Stimulator of Interferon Genes (STING) is a dsDNA sensor that triggers type I inflammatory responses. Recent data from our group and others support the therapeutic efficacy of STING agonists applied intratumorally or systemically in a range of murine tumor models, with treatment benefits associated with tumor vascular normalization and improved immune cell recruitment and function within the tumor microenvironment (TME). However, such interventions are rarely curative and STING agonism coordinately upregulates expression of immunoregulatory interferon-stimulated genes (ISGs) including Arg2, Cox2, Isg15, Nos2, and Pdl1 that may limit treatment benefits. We hypothesized that combined treatment of melanoma-bearing mice with STING agonist ADU-S100 together with antagonists of regulatory ISGs would result in improved control of tumor growth vs. treatment with ADU-S100 alone. Methods: Mice bearing either B16 (BRAFWTPTENWT) or BPR20 (BRAFV600EPTEN-/-) melanomas were treated with STING agonist ADU-S100 plus various inhibitors of ARG2, COX2, NOS2, PD-L1, or ISG15. Tumor growth control and changes in the TME were evaluated for combination treatment vs ADU-S100 monotherapy by tumor area measurements and flow cytometry/transcriptional profiling, respectively. Results: In the B16 melanoma model, we noted improved antitumor efficacy only when ADU-S100 was combined with neutralizing/blocking antibodies against PD-L1 or ISG15, but not inhibitors of ARG2, COX2, or NOS2. Conversely, in the BPR20 melanoma model, improved tumor growth control vs. ADU-S100 monotherapy was only observed when combining ADU-S100 with ARG2i, COX2i, and NOS2i, but not anti-PD-L1 or anti-ISG15. Immune changes in the TME associated with improved treatment outcomes were subtle but included increases in proinflammatory innate immune cells and activated CD8+CD69+ T cells and varied between the two tumor models. Conclusions: These data suggest contextual differences in the relative contributions of individual regulatory ISGs that serve to operationally limit the anti-tumor efficacy of STING agonists which should be considered in future design of novel combination protocols for optimal treatment benefit.

NK Receptor Signaling Lowers TCR Activation Threshold, Enhancing Selective Recognition of Cancer Cells by TAA-Specific CTLs.

CTL recognition of non-mutated tumor-associated antigens (TAA), present on cancer cells but also in healthy tissues, is an important element of cancer immunity, but the mechanism of its selectivity for cancer cells and opportunities for its enhancement remain elusive. In this study, we found that CTL expression of the NK receptors (NKR) DNAM-1 and NKG2D was associated with the effector status of CD8+ tumor-infiltrating lymphocytes (TIL) and long-term survival of melanoma patients. Using MART-1 and NY-ESO-1 as model TAAs, we demonstrated that DNAM-1 and NKG2D regulate T-cell receptor (TCR) functional avidity and set the threshold for TCR activation of human TAA-specific CTLs. Superior costimulatory effects of DNAM-1 over CD28 involved enhanced TCR signaling, CTL killer function and polyfunctionality. Double transduction of human CTLs with TAA-specific TCR and NKRs resulted in strongly enhanced antigen sensitivity, without a reduction in the antigen specificity and selectivity of killer function. In addition, the elevation of NKR-Ligand expression on cancer cells by chemotherapy also increased CTL recognition of cancer cells expressing low levels of TAA. Our data help to explain the ability of self-antigens to mediate tumor rejection in the absence of autoimmunity and support the development of dual-targeting adoptive T cell therapies that use NKRs to enhance the potency and selectivity of recognition of TAA-expressing cancer cells.

Combined Tbet and IL12 gene therapy elicits and recruits superior antitumor immunity in vivo.

We have recently shown that intratumor (i.t.) injection of syngenic dendritic cells (DC) engineered to express the transcription factor Tbet (TBX21) promotes protective type-1 T cell-mediated immunity via a mechanism that is largely interleukin (IL)-12p70-independent. Since IL-12 is a classical promoter of type-1 immunity, the current study was undertaken to determine whether gene therapy using combined Tbet and IL-12 complementary DNA (cDNA) would yield improved antitumor efficacy based on the complementary/synergistic action of these biologic modifiers. Mice bearing established subcutaneous (s.c.) tumors injected with DC concomitantly expressing ectopic Tbet and IL12 (i.e., DC.Tbet/IL12) displayed superior (i) rates of tumor rejection and extended overall survival, (ii) cross-priming of Tc1 reactive against antigens expressed within the tumor microenvironment, and (iii) infiltration of CD8(+) T cells into treated tumors in association with elevated locoregional production of CXCR3 ligand chemokines. In established bilateral tumor models, i.t. delivery of DC.Tbet/IL12 into a single lesion led to slowed growth or regression at both tumor sites. Furthermore, DC.Tbet/IL12 pulsed with tumor antigen-derived peptides and injected as a therapy distal to the tumor site prevented tumor growth and activated robust antigen-specific Tc1 responses. These data support the translation use of combined Tbet and IL-12p70 gene therapy in the cancer setting.

NK Receptors Replace CD28 As the Dominant Source of Signal 2 for Cognate Recognition of Cancer Cells by TAA-specific Effector CD8+ T Cells.

CD28-driven "signal 2" is critical for naïve CD8+ T cell responses to dendritic cell (DC)-presented weak antigens, including non-mutated tumor-associated antigens (TAAs). However, it is unclear how DC-primed cytotoxic T lymphocytes (CTLs) respond to the same TAAs presented by cancer cells which lack CD28 ligands. Here, we show that NK receptors (NKRs) DNAM-1 and NKG2D replace CD28 during CTL re-activation by cancer cells presenting low levels of MHC I/TAA complexes, leading to enhanced proximal TCR signaling, immune synapse formation, CTL polyfunctionality, release of cytolytic granules and antigen-specific cancer cell killing. Double-transduction of T cells with recombinant TCR and NKR constructs or upregulation of NKR-ligand expression on cancer cells by chemotherapy enabled effective recognition and killing of poorly immunogenic tumor cells by CTLs. Operational synergy between TCR and NKRs in CTL recognition explains the ability of cancer-expressed self-antigens to serve as tumor rejection antigens, helping to develop more effective therapies.