Issues Need to be Resolved With Immuno-Modulatory Therapies: NK cells, mAbs, and adoptive T cells
Curator: Stephen J. Williams, PhD
Immunotherapy. 2014;6(3):309-20. doi: 10.2217/imt.13.175.
Carreño LJ1, Kharkwal SS, Porcelli SA.
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Abstract
NKT cells are a subpopulation of T lymphocytes with phenotypic properties of both T and NK cells and a wide range of immune effector properties. In particular, one subset of these cells, known as invariant NKT cells (iNKT cells), has attracted substantial attention because of their ability to be specifically activated by glycolipid antigens presented by a cell surface protein called CD1d. The development of synthetic α-galactosylceramides as a family of powerful glycolipid agonists for iNKT cells has led to approaches for augmenting a wide variety of immune responses, including those involved in vaccination against infections and cancers. Here, we review basic, preclinical and clinical observations supporting approaches to improving immune responses through the use of iNKT cell-activating glycolipids. Results from preclinical animal studies and preliminary clinical studies in humans identify many promising applications for this approach in the development of vaccines and novel immunotherapies.
Cancer Res. 2013 Jul 1;73(13):3842-51. doi: 10.1158/0008-5472.CAN-12-1974. Epub 2013 May 23.
Avirulent Toxoplasma gondii generates therapeutic antitumor immunity by reversing immunosuppression in the ovarian cancer microenvironment.
Baird JR1, Fox BA, Sanders KL, Lizotte PH, Cubillos-Ruiz JR, Scarlett UK, Rutkowski MR, Conejo-Garcia JR, Fiering S, Bzik DJ.
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Abstract
Reversing tumor-associated immunosuppression seems necessary to stimulate effective therapeutic immunity against lethal epithelial tumors. Here, we show this goal can be addressed using cps, an avirulent, nonreplicating uracil auxotroph strain of the parasite Toxoplasma gondii (T. gondii), which preferentially invades immunosuppressive CD11c(+) antigen-presenting cells in the ovarian carcinoma microenvironment. Tumor-associated CD11c(+) cells invaded by cps were converted to immunostimulatory phenotypes, which expressed increased levels of the T-cell receptor costimulatory molecules CD80 and CD86. In response to cps treatment of the immunosuppressive ovarian tumor environment, CD11c(+) cellsregained the ability to efficiently cross-present antigen and prime CD8(+) T-cell responses. Correspondingly, cps treatment markedly increased tumor antigen-specific responses by CD8(+) T cells. Adoptive transfer experiments showed that these antitumor T-cell responses were effective in suppressing solid tumor development. Indeed, intraperitoneal cps treatment triggered rejection of established ID8-VegfA tumors, an aggressive xenograft model of ovarian carcinoma, also conferring a survival benefit in a related aggressive model (ID8-Defb29/Vegf-A). The therapeutic benefit of cps treatment relied on expression of IL-12, but it was unexpectedly independent of MyD88 signaling as well as immune experience with T. gondii. Taken together, our results establish that cps preferentially invades tumor-associated antigen-presenting cells and restores their ability to trigger potent antitumor CD8(+) T-cell responses. Immunochemotherapeutic applications of cps might be broadly useful to reawaken natural immunity in the highly immunosuppressive microenvironment of most solid tumors.
Oncoimmunology. 2013 Jun 1;2(6):e24677. Epub 2013 Apr 29.
TLR3 agonists improve the immunostimulatory potential of cetuximab against EGFR+ head and neck cancer cells.
Ming Lim C1, Stephenson R, Salazar AM, Ferris RL.
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Abstract
Toll-like receptor 3 (TLR3) agonists have been extensively used as adjuvants for anticancer vaccines. However, their immunostimulatory effects and precise mechanisms of action in the presence of antineoplastic monoclonal antibodies (mAbs) have not yet been evaluated. We investigated the effect of TLR3 agonists on cetuximab-mediated antibody-dependent cellular cytotoxicity (ADCC) against head and neck cancer (HNC) cells, as well as on dendritic cell (DC) maturation and cross-priming of epidermal growth factor receptor (EGFR)-specific CD8+ T cells. The cytotoxic activity of peripheral blood mononuclear cells (PBMCs) or isolated natural killer (NK) cells expressing polymorphic variants (at codon 158) of the Fcγ receptor IIIa (FcγIIIa) was determined in 51Cr release assays upon incubation with the TLR3 agonist poly-ICLC. NK cell stimulation was measured based on activation and degranulation markers, while DC maturation in the presence of poly-ICLC was assessed using flow cytometry. The DC-mediated cross priming of EGFR-specific CD8+ T cells was monitored upon in vitro stimulation with tetramer-based flow cytometry. TLR3-stimulated, unfractionated PBMCs from HNC patients mediated robust cetuximab-dependent ADCC, which was abrogated by NK-cell depletion. The cytolytic activity of TLR3-stimulated NK cells differed among cells expressing different polymorphic variants of FcγRIIIa, and NK cells exposed to both poly-ICLC and cetuximab expressed higher levels of CD107a and granzyme B than their counterparts exposed to either stimulus alone. Poly-ICLC plus cetuximab also induced a robust upregulation of CD80, CD83 and CD86 on the surface of DCs, a process that was partially NK-cell dependent. Furthermore, DCs matured in these conditions exhibited improved cross-priming abilities, resulting in higher numbers of EGFR-specific CD8+ T cells. These findings suggest that TLR3 agonists may provide a convenient means to improve the efficacy of mAb-based anticancer regimens.
Ann Oncol. 2012 Sep; 23(Suppl 8): viii6–viii9.
doi: 10.1093/annonc/mds256
PMCID: PMC4085883
- J. Finn*
Interactions between the Immune System and Cancer
Evidence has been accumulating since the middle of the last century, first from animal models and later from studies in cancer patients, that the immune system can recognise and reject tumours. The goal of tumour immunology has been to understand the components of the immune system that are important for tumour immunosurveillance and tumour rejection to understand how, when, and why they fail in cases of clinical disease. Immunotherapy, which involves strengthening the cancer patient’s immune system by improving its ability to recognise the tumour or providing a missing immune effector function, is one treatment approach that holds promise of a life-long cure [4].
Studies of cancer–immune system interactions have revealed that every known innate and adaptive immune effector mechanism participates in tumour recognition and control [5]. The first few transformed cells are detected by NK cells through their encounter with specific ligands on tumour cells. This leads to the destruction of some transformed cells and the uptake and processing of their fragments by macrophages and dendritic cells. In turn, these macrophages and dendritic cells are activated to secrete many inflammatory cytokines and present tumour cell-derived molecules to T- and B cells. Activation of T- and B cells leads to the production of additional cytokines that further promote activation of innate immunity and support the expansion and production of tumour-specific T cells and antibodies, respectively. The full power of the adaptive immune system leads to the elimination of remaining tumour cells and, importantly, to the generation of immune memory to specific tumour components that will serve to prevent tumour recurrence.
Effectors of adaptive immunity, such as CD4+ helper T cells, CD8+ cytotoxic T cells, and antibodies, specifically target tumour antigens; i.e. molecules expressed in tumour cells, but not in normal cells. Tumour antigens are normal cellular proteins that are abnormally expressed as a result of genetic mutations, quantitative differences in expression, or differences in posttranslational modifications [5]. In tumour types that have a well-documented viral origin, such as cervical cancer, caused by the human papillomavirus [5], or hepatocellular carcinoma caused by the hepatitis B virus [6], viral proteins can also serve as tumour antigens and targets for antitumour immune response [7].
The first indication that tumours carried molecules distinct from those on the normal cell of origin was derived from immunising mice with human tumours and selecting antibodies that recognised human tumour cells but not their normal counterparts. The major question was whether some, or all, of these molecules would also be recognised by the human immune system. 2011 was an important anniversary for human tumour immunology, marking 20 years since the publication by van der Bruggen et al. [8] that described the cloning of MAGE-1, a gene that encodes a human melanoma antigen recognised by patient’s antitumour T cells. This was not a mutant protein; its recognition by the immune system was due to the fact that it was only expressed by transformed, malignant cells and, with the exception of testicular germ cells, was not expressed in normal adult tissue. Many similar discoveries followed, with each new molecule providing a better understanding of what might be good targets for different forms of cancer immunotherapy. Tumour antigens have been tested as vaccines, as targets for monoclonal antibodies, and as targets for adoptively transferred cytotoxic T cells. There is a wealth of publications from preclinical studies targeting these antigens and results from phase I/II clinical trials. Recently, these studies were critically reviewed and a list of tumour antigens with the largest body of available data compiled [9]. The goal was to encourage faster progress in the design, testing, and approval of immunotherapeutic reagents that incorporate or target the most promising antigens.
As highlighted in the article two scenarios which present problems emerged:
- In the past, immunotherapy was referred to as ‘passive’ (e.g. the infusion of preformed immune effectors, such as antibodies, cytokines, or activated T cells, NK cells, or lymphokine-activated killer cells), presumably acting directly on the tumour and independent of the immune system or ‘active’ (e.g. vaccines), designed to activate and therefore be dependent on the patient’s immune system. it has since become clear that both passive and active immunotherapies depend on the patient’s immune system for long-term tumour control or complete tumour elimination. anticancer monoclonal antibodies are a well-established class of immunotherapeutic agent. HOWEVER, The potential of these antibodies is drastically undermined by their administration relatively late in the disease course, when the patient’s immune system is largely compromised. Under more optimal conditions, antibody treatment might result not only in the direct cytostatic or cytotoxic effect on the tumour cell, but also in the loading of antibody-bound tumour antigens onto antigen presenting cells (APC) in the tumour microenvironment. The resultant cross-presentation to antitumour T- and B cells could result in additional antibodies to these antigens being produced, and propagation of the immune response at the tumour site would maintain tumour elimination long after the infused monoclonal antibody is gone.
- The same scenario could be predicted for adoptively transferred T cells. Unlike antibodies, transferred T cells persist longer and may provide a memory response [14]; however, as long as the memory response is restricted to one clone, or a limited number of clones, then antigen-negative tumours will be able to escape. In addition, cancer vaccines encounter large numbers of immunosuppressive Tregand MDSC in circulation, as well as immunosuppressive cell-derived soluble products that flood the lymph nodes, preventing maturation of APCs and activation of T cells. Even when vaccines are delivered in the context of ex vivo matured and activated dendritic cells, their ability to activate T cells is compromised by the high-level expression of various molecules on T cells that block this process.
The scenarios proposed above present a rather bleak picture of the potential of immunotherapy to achieve the cure for cancer that has eluded standard therapy [15]. Interestingly, failures of some standard therapies are beginning to be ascribed to their inability to activate the patient’s immune system [16]. However, rather than seeing the picture as a deterrent, it should be considered as a road map, providing at least two major directions for new developments in immunotherapy.
The first direction is to continue using the old classes of immunotherapy that target the cancer directly, but to use them in combination with therapies that target the immune system in the tumour microenvironment, such as cytokines, suppressors of Treg or MDSC activity, or antibodies that modulate T-cell activity. The recently approved antibody, ipilimumab, which acts to sustain cytotoxic T-cell activity by augmenting T-cell activation and proliferation, is one example of such an immunomodulatory agent [17].
The other direction is to use immunotherapies, both old and new, for preventing cancer in individuals at high risk [18]. Studies of the tumour microenvironment are providing information about immunosurveillance of tumours from early premalignant lesions to more advanced dysplastic lesions to cancer. At each step, tumour-derived and immune system-derived components have a unique composition that will have distinct effects on immunotherapy. Because these premalignant microenvironments are less developed and immunosuppression is less entrenched, it should be easier to modulate towards the elimination of abnormal cells.
Cancer Immunol Immunother. 2011 Sep;60(9):1309-17. doi: 10.1007/s00262-011-1038-y. Epub 2011 May 28.
Geary SM1, Lemke CD, Lubaroff DM, Salem AK.
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Abstract
The combination of viral vaccination with intratumoral (IT) administration of CpG ODNs is yet to be investigated as an immunotherapeutic treatment for solid tumors. Here, we show that such a treatment regime can benefit survival of tumor-challenged mice. C57BL/6 mice bearing ovalbumin (OVA)-expressing EG.7 thymoma tumors were therapeutically vaccinated with adenovirus type 5 encoding OVA (Ad5-OVA), and the tumors subsequently injected with the immunostimulatory TLR9 agonist, CpG-B ODN 1826 (CpG), 4, 7, 10, and 13 days later. This therapeutic combination resulted in enhanced mean survival times that were more than 3.5× longer than naïve mice, and greater than 40% of mice were cured and capable of resisting subsequent tumor challenge. This suggests that an adaptive immune response was generated. Both Ad5-OVA and Ad5-OVA + CpG IT treatments led to significantly increased levels of H-2 K(b)-OVA-specific CD8+ lymphocytes in the peripheral blood and intratumorally. Lymphocyte depletion studies performed in vivo implicated both NK cells and CD8+ lymphocytes as co-contributors to the therapeutic effect. Analysis of tumor infiltrating lymphocytes (TILs) on day 12 post-tumor challenge revealed that mice treated with Ad5-OVA + CpG IT possessed a significantly reduced percentage of regulatory T lymphocytes (Tregs) within the CD4+ lymphocyte population, compared with TILs isolated from mice treated with Ad5-OVA only. In addition, the proportion of CD8+ TILs that were OVA-specific was reproducibly higher in the mice treated with Ad5-OVA + CpG IT compared with other treatment groups. These findings highlight the therapeutic potential of combining intratumoral CpG and vaccination with virus encoding tumor antigen.
Adv Drug Deliv Rev. 2009 Mar 28;61(3):268-74. doi: 10.1016/j.addr.2008.12.005. Epub 2009 Jan 7.
Lubaroff DM1, Karan D.
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Abstract
The use of an adenovirus transduced to express a prostate cancer antigen (PSA) as a vaccine for the treatment of prostate cancer has been shown to be active in the destruction of antigen-expressing prostate tumor cells in a pre-clinical model, using Balb/C or PSA transgenic mice. The destruction of PSA-secreting mouse prostate tumors was observed in Ad/PSA immunized mice in a prophylaxis study with 70% of the mice surviving long term tumor free. This successful immunotherapy was not observed in therapeutic studies in which tumors were established before vaccination and the development of anti-PSA immune response was not as easily generated in PSA transgenic mice. Immunization of conventional and transgenic animals was enhanced by incorporating a collagen matrix into the immunizing injection. Therefore the need to strengthen anti-PSA and anti-prostate cancer immunity was an obvious next step in developing a successful prostate cancer immunotherapy. Because the use ofimmunostimulatory CpG motifs was shown to enhance immune responses to a wide variety of antigens, our studies incorporated CpG into the Ad/PSA vaccine experimental plans. The results of the subsequent studies demonstrated a dichotomy where Ad/PSA plus CpG enhanced the in vivo destruction of PSA-secreting tumors and the survival of experimental animals, but revealed that the number and in vitro activities of antigen specific CD8+ T cells was decreased as compared to the values observed when the vaccine alone was used for immunization. The dichotomous observations were confirmed using another antigen system, OVA also incorporated into a replication defective adenovirus. Despite the reduction in antigen-specific CD8+ cells after vaccine plus CpG immunization the enhanced destruction of sc and systemic tumors was shown to be mediated entirely by CD8+ T cells. Finally, the reduction of the CD8+ T cells was the result of an observed decrease in the proliferation of the antigen specific cell population.
J Invest Dermatol. 2004 Aug;123(2):371-9.
Schneeberger A1, Wagner C, Zemann A, Lührs P, Kutil R, Goos M, Stingl G, Wagner SN.
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Abstract
DNA vaccines can induce impressive specific cellular immune response (IR) when taking advantage of their recognition as pathogen-associated molecular patterns (PAMP) through Toll-like receptors (TLR) expressed on/in cells of the innate immune system. Among the many types of PAMP,immunostimulatory DNA, so-called CpG motifs, was shown to interact specifically with TLR9, which is expressed in plasmacytoid dendritic cells(pDC), a key regulatory cell for the activation of innate and adaptive IR. We now report that CpG motifs, when introduced into the backbone, are a useful adjuvant for plasmid-based DNA (pDNA) vaccines to induce melanoma antigen-specific protective T cell responses in the Cloudman M3/DBA/2 model. The CpG-enriched pDNA vaccine induced protection against subsequent challenge with melanoma cells at significantly higher levels than its parental unmodified vector. Preferential induction of an antigen-specific, protective T cell response could be demonstrated by (i) induction of antigen-dependent tumor cell protection, (ii) complete loss of protection by in vivo CD4+/CD8+T cell- but not NK cell-depletion, and (iii) the detection of antigen-specific T cell responses but not of relevant NK cell activity in vitro. These results demonstrate that employing PAMP in pDNA vaccines improves the induction of protective, antigen-specific, T cell-mediated IR.
J Biomed Sci. 2016 Jan 25;23(1):16. doi: 10.1186/s12929-016-0238-3.
Gableh F1, Saeidi M2, Hemati S3, Hamdi K4, Soleimanjahi H5, Gorji A6,7,8, Ghaemi A9,10,11.
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Abstract
BACKGROUND:
DNA vaccines have emerged as an attractive approach for the generation of cytotoxic T lymphocytes (CTL). In our previous study, we found That Toll like receptor (TLR) ligands are promising candidates for the development of novel adjuvants for DNA vaccine. To improve the efficacy of DNA vaccine directed against human papillomavirus (HPV) tumors, we evaluated whether co-administration of a TLR4 ligand, monophosphoryl lipid A (MPL), and Natural Killer T Cell Ligand α-Galactosylceramide(α-GalCer) adjuvants with DNA vaccine would influence the anti-tumor efficacy of DNA vaccinations.
METHODS:
We investigated the effectiveness of α-GalCer and MPL combination as an adjuvant with an HPV-16 E7 DNA vaccine to enhance antitumor immune responses.
RESULTS:
By using adjuvant combination for a DNA vaccine, we found that the levels of lymphocyte proliferation, CTL activity, IFN- γ, IL-4 and IL-12 responses, and tumor protection against TC-1 cells were significantly increased compared to the DNA vaccine with individual adjuvants. In addition, inhibition of IL-18 signaling during vaccination decreased IFN-γ responses and tumor protection, and that this inhibition suggested stimulatory role of IL-18 in adjuvant effects of α-GalCer and MPL combination.
CONCLUSION:
The strong adjuvanticity associated with α-GalCer/MPL combination may to be an important tool in the development of novel and strong cancer immunotherapy.
Cancer Sci. 2015 Dec;106(12):1659-68. doi: 10.1111/cas.12824. Epub 2015 Nov 18.
Seya T1, Shime H1, Takeda Y1, Tatematsu M1, Takashima K1, Matsumoto M1.
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Abstract
Immune-enhancing adjuvants usually targets antigen (Ag)-presenting cells to tune up cellular and humoral immunity. CD141(+) dendritic cells (DC) represent the professional Ag-presenting cells in humans. In response to microbial pattern molecules, these DCs upgrade the maturation stage sufficient to improve cross-presentation of exogenous Ag, and upregulation of MHC and costimulators, allowing CD4/CD8 T cells to proliferate and liberating cytokines/chemokines that support lymphocyte attraction and survival. These DCs also facilitate natural killer-mediated cell damage. Toll-like receptors (TLRs) and their signaling pathways in DCs play a pivotal role in DC maturation. Therefore, providing adjuvants in addition to Ag is indispensable for successful vaccine immunotherapy for cancer, which has been approved in comparison with antimicrobial vaccines. Mouse CD8α(+) DCs express TLR7 and TLR9 in addition to the TLR2 family (TLR1, 2, and 6) and TLR3, whereas human CD141(+) DCs exclusively express the TLR2 family and TLR3. Although human and mouse plasmacytoid DCs commonly express TLR7/9 to respond to their agonists, the results on mouse adjuvant studies using TLR7/9 agonists cannot be simply extrapolated to human adjuvant immunotherapy. In contrast, TLR2 and TLR3 are similarly expressed in both human and mouse Ag-presenting DCs. Bacillus Calmette-Guerin peptidoglycan and polyinosinic-polycytidylic acid are representative agonists for TLR2 and TLR3, respectively, although they additionally stimulate cytoplasmic sensors: their functional specificities may not be limited to the relevant TLRs. These adjuvants have been posted up to a certain achievement in immunotherapy in some cancers. We herein summarize the history and perspectives of TLR2 and TLR3 agonists in vaccine-adjuvant immunotherapy for cancer.
Adv Exp Med Biol. 2015;850:81-91. doi: 10.1007/978-3-319-15774-0_7.
Beaulieu AM1, Madera S, Sun JC.
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Abstract
Immunological memory is a hallmark of the adaptive immune system. Although natural killer (NK) cells have traditionally been classified as a component of the innate immune system, they have recently been shown in mice and humans to exhibit certain features of immunological memory, including an ability to undergo a clonal-like expansion during virus infection, generate long-lived progeny (i.e. memory cells), and mediate recall responses against previously encountered pathogens–all characteristics previously ascribed only to adaptive immune responses by B and T cells in mammals. To date, the molecular events that govern the generation of NK cell memory are not completely understood. Using a mouse model of cytomegalovirus infection, we demonstrate that individual pro-inflammatory IL-12, IL-18, and type I-IFN signaling pathways are indispensible and play non-redundant roles in the generation of virus-specific NK cell memory. Furthermore, we discovered that antigen-specific proliferation and protection by NK cells is mediated by the transcription factor Zbtb32, which is induced by pro-inflammatory cytokines and promotes a cell cycle program in activated NK cells. A greater understanding of the molecular mechanisms controlling NK cell responses will provide novel strategies for tailoring vaccines to target infectious disease.
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