Novel gamma-chain cytokines as candidate immune modulators in immune therapies for cancer

BCG vaccination induces enhanced frequencies of memory T cells and altered plasma levels of common γc cytokines in elderly individuals

BCG vaccination is known to induce innate immune memory, which confers protection against heterologous infections. However, the effect of BCG vaccination on the conventional adaptive immune cells subsets is not well characterized. We investigated the impact of BCG vaccination on the frequencies of T cell subsets and common gamma c (γc) cytokines in a group of healthy elderly individuals (age 60–80 years) at one month post vaccination as part of our clinical study to examine the effect of BCG on COVID-19. Our results demonstrate that BCG vaccination induced enhanced frequencies of central (p<0.0001) and effector memory (p<0.0001) CD4+ T cells and diminished frequencies of naïve (p<0.0001), transitional memory (p<0.0001), stem cell memory (p = 0.0001) CD4+ T cells and regulatory T cells. In addition, BCG vaccination induced enhanced frequencies of central (p = 0.0008), effector (p<0.0001) and terminal effector memory (p<0.0001) CD8+ T cells and diminished frequencies of naïve (p<0.0001), transitional memory (p<0.0001) and stem cell memory (p = 0.0034) CD8+T cells. BCG vaccination also induced enhanced plasma levels of IL-7 (p<0.0001) and IL-15 (p = 0.0020) but diminished levels of IL-2 (p = 0.0033) and IL-21 (p = 0.0020). Thus, BCG vaccination was associated with enhanced memory T cell subsets as well as memory enhancing γc cytokines in elderly individuals, suggesting its ability to induce non-specific adaptive immune responses.

Saffron anti-metastatic properties, ancient spice novel application

Crocus sativus L. (saffron), was applied as a spice, food colorant and medicine since four millennia ago and has been used as a remedy for various maladies. In the last three decades, the anti-primary tumor properties of saffron and its main carotenoids, crocin and crocetin, have been well explored. Despite the fact that metastasis is the leading cause of death in cancer patients, the anti-metastatic potential of saffron and its carotenoids has been surveyed only this decade. This review aims to provide an unprecedented overview of the anti-metastatic effects of saffron, crocin and crocetin, and the mechanisms underlying these effects. Investigations on various cancers demonstrated the anti-migratory, anti-invasion, anti-angiogenic potentials of saffron and its carotenoids, as well as their effects suppressing cell-ECM adhesion and enhancing cell-cell attachment. Saffron and its carotenoids exert their impact through different mechanisms such as reduction of CD34 and suppression of Wnt/β-catenin, Ras/ERK, P38, DCLK1, EMT, matrix metalloproteinases and urokinases. Crocin displayed more effective anti-metastatic potency, in comparison with saffron extract and crocetin. The bioaccessibility/bioavailability, nontoxicity on normal cells, confirmed anti-tumor efficiency and the recent evidence on the anti-metastatic potential of saffron and its carotenoids, recommends them as a propitious multipotent dietary agent and herbal medicine.

Nicotine exhausts CD8+ T cells against tumor cells through increasing miR-629-5p to repress IL2RB-mediated granzyme B expression

The mechanism exhausting CD8⁺ T cells is not completely clear against tumors. Literature has demonstrated that cigarette smoking disables the immunological activity, so we propose nicotine is able to exhaust CD8⁺ T cells. The CD8⁺ T cells from healthy volunteers with and without cigarette smoking and the capacity of CD8⁺ T cells against tumor cells were investigated. RNAseq was used to investigate the gene profiling expression in CD8⁺ T cells. Meanwhile, small RNAseq was also used to search novel microRNAs involved in the exhaustion of CD8⁺ T cells. The effect of nicotine exhausting CD8⁺ T cells was investigated in vitro and in the humanized tumor xenografts in vivo. We found that CD8⁺ T cells were able to reduce cell viability in lung cancer HCC827 and A549 cells, that secreted granzyme B, but CD8⁺ T cells from the healthy cigarette smokers lost anti-HCC827 effect. Moreover, nicotine suppressed the anti-HCC827 effect of CD8⁺ T cells. RNAseq revealed lower levels of IL2RB and GZMB in the exhausted CD8⁺ T cells. We identified that miR-629-5p was increased by nicotine, that targeted IL2RB. Transfection of miR-629-5p mimic reduced IL2RB and GZMB levels. We further validated that nicotine reduced granzyme B levels using a nuclear imaging technique, and demonstrated that nicotine exhausted peripheral blood mononuclear cells against HCC827 growth in the humanized tumor xenografts. This study demonstrated that nicotine exhausted CD8⁺ T cells against HCC827 cells through increasing miR-629-5p to suppress IL2RB.

Cytokines as potential combination agents with PD-1/PD-L1 blockade for cancer treatment

Immunotherapy has caused a paradigm shift in the treatment of several malignancies, particularly the blockade of programmed death-1 (PD-1) and its specific receptor/ligand PD-L1 that have revolutionized the treatment of a variety of malignancies, but significant durable responses only occur in a small percentage of patients, and other patients failed to respond to the treatment. Even those who initially respond can ultimately relapse despite maintenance treatment, there is considerable potential for synergistic combinations of immunotherapy and chemotherapy agents with immune checkpoint inhibitors into conventional cancer treatments. The clinical experience in the use of cytokines in the clinical setting indicated the efficiency of cytokine therapy in cancer immunotherapy. Combinational approaches to enhancing PD-L1/PD-1 pathways blockade efficacy with several cytokines such as interleukin (IL)-2, IL-15, IL-21, IL-12, IL-10, and interferon-α (IFN-α) may result in additional benefits. In this review, the current state of knowledge about PD-1/PD-L1 inhibitors, the date in the literature to ascertain the combination of anti-PD-1/PD-L1 antibodies with cytokines is discussed. Finally, it is noteworthy that novel therapeutic approaches based on the efficient combination of recombinant cytokines with the PD-L1/PD-1 blockade therapy can enhance antitumor immune responses against various malignancies.

IL-2 And IL-15 Induced NKG2D, CD158a and CD158b Expression on T, NKT- like and NK Cell Lymphocyte Subsets from Regional Lymph Nodes of Melanoma Patients

Regional lymph nodes (LN)s represent important immunological barriers in spreading of malignant tumors. However, they are the most frequent early metastatic site in melanoma. Immunomodulatory agents including cytokines have been included in therapy of melanoma and have shown severe side effects and toxicity. In this sense, there is a growing need for bringing these agents to further in vitro testing that may enlighten aspects of their regional application. Therefore, the aim of this study was to investigate the effect of interleukin (IL)-2 and IL-15, the two cytokines with similar immune-enhancing effects, on the expression of activating NKG2D, inhibitory CD158a and CD158b receptors on CD8+ T, NKT-like and NK cell lymphocyte subsets from regional LNs of melanoma patients. In this study, we showed significant effects of IL-2 and IL-15 cytokine treatments on the expression of activating NKG2D and on inhibitory CD158a and CD158b receptors on lymphocytes, CD8+ T, NKT-like and NK cell lymphocyte subsets originating from regional LNs of melanoma patients. Furthermore, IL-2 and IL-15 by inducing the expression of NKG2D activating receptor on innate and on adaptive lymphocyte subsets and by augmenting NK cell antitumor cytotoxicity that correlated with the cytokine-induced NKG2D expression, increased antitumor potential of immune cells in regional LNs of melanoma patients irrespective of LN involvement. These findings indicate the importance of immune cell population from regional LNs of melanoma patients in the development of immune intervention strategies that may if applied locally increase antitumor potential to the level that controls tumor progressions.

Dietary Crocin Reverses Melanoma Metastasis

Crocus sativus and its bioactive constituent crocin are well known for anti-tumor potential in different models. However, the efficacy of crocin on in-vivo melanoma metastasis is not yet reported. In this study, melanoma metastatic model was developed by tail vein injection of B16F-10 cells in to C57BL/6 mice. Metastatic mice treated with two different doses of crocin (250 and 500 µg/kg of bodyweight) for 10 days and parameters such as lung metastasis inhibition, mean survival time, lung hydroxyproline, uronic acid and hexosamine levels were analyzed after 21 days of treatment. Then blood was collected and serum gamma glutamyl transpeptidase (g-GGT), sialic acid, tumor necrosis factor alpha (TNF-a), interleukin 10 (IL-10), IL-6, IL-2, and TIMP-1 levels were measured. Further, a lung histological examination was done in crocin treated metastatic mice. Subsequently hallmark metastatic parameters such as matrix metalloproteases (MMPs), extracellular regulated kinase 2 (ERK2), vascular endothelial growth factor (VEGF), and K-ras gene expression were investigated in the lungs of crocin treated metastatic mice. Further, in-vitro adhesion, invasion and migration of B16F-10 cells were examined after 24 h of crocin (5 and 10 µg/mL) treatment. Administration of crocin to tumor bearing C57BL/6 mice reduced the lung metastasis by 85%. Elevated levels of hydroxyproline, uronic acid, hexosamine, serum sialic acid andg-GGT in metastatic control were found to be significantly reduced in crocin treated mice. Crocin also inhibited expression of MMP-2, MMP-9, ERK-2, K-ras, and VEGF. Crocin reduced the ability of B16F-10 cells invasion (p<0.05), migration (p<0.05) and adhesion by upregulating E-cadherin expression. In conclusion, crocin elicited marked anti-metastatic potential by regulating the metastasis induced biomarkers.

Exhaustion of T lymphocytes in the tumor microenvironment: Significance and effective mechanisms

T lymphocytes play crucial roles in adaptive immune responses to tumors. However, due to different tolerance mechanisms and inhibitory effects of the tumor microenvironment (TME) on T cells, responses to tumors are insufficient. In fact, cellular and molecular suppressive mechanisms repress T cell responses in the TME, resulting in senescent, anergic and exhausted lymphocytes. Exhaustion is a poor responsive status of T cells, with up-regulated expression of inhibitory receptors, decreased production of effective cytokines, and reduced cytotoxic activity. Low immunogenicity of tumor antigens and inadequate presentation of tumor-specific antigens results in inappropriate activation of naive T lymphocytes against tumor antigens. Moreover, when effector cytotoxic T cells enter TME, they encounter a complicated network of cells and cytokines that suppress their effectiveness and turn them into exhausted T cells. Thus, the mechanism of T cell exhaustion in cancer is different from that in chronic infections. In this review we will discuss the main components such as inhibitory receptors, inflammatory cells, stromal cells, cytokine milieu as well as environmental and metabolic conditions in TME which play role in development of exhaustion. Furthermore, recent therapeutic methods available to overcome exhaustion will be discussed.

Interleukin-21 combined with PD-1 or CTLA-4 blockade enhances antitumor immunity in mouse tumor models

Recent advances in cancer treatment with checkpoint blockade of receptors such as CTLA-4 and PD-1 have demonstrated that combinations of agents with complementary immunomodulatory effects have the potential to enhance antitumor activity as compared to single agents. We investigated the efficacy of immune-modulatory interleukin-21 (IL-21) combined with checkpoint blockade in several syngeneic mouse tumor models. After tumor establishment, mice were administered recombinant mouse IL-21 (mIL-21) alone or in combination with blocking monoclonal antibodies against mouse PD-1 or CTLA-4. In contrast to monotherapy, IL-21 enhanced antitumor activity of mCTLA-4 mAb in four models and anti-PD-1 mAb in two models, with evidence of synergy for one or both of the combination treatments in the EMT-6 and MC38 models. The enhanced efficacy was associated with increased intratumoral CD8+ T cell infiltrates, CD8+ T cell proliferation, and increased effector memory T cells, along with decreased frequency of central memory CD8+ T cells. In vivo depletion of CD8+ T cells abolished the antitumor activities observed for both combination and monotherapy treatments, further supporting a beneficial role for CD8+ T cells. In all studies, the combination therapies were well tolerated. These results support the hypothesis that the combination of recombinant human IL-21 with CTLA-4 or PD-1 monoclonal antibodies could lead to improved outcomes in cancer patients.

Starved and Asphyxiated: How Can CD8(+) T Cells within a Tumor Microenvironment Prevent Tumor Progression

Although cancer immunotherapy has achieved significant breakthroughs in recent years, its overall efficacy remains limited in the majority of patients. One major barrier is exhaustion of tumor antigen-specific CD8(+) tumor-infiltrating lymphocytes (TILs), which conventionally has been attributed to persistent stimulation with antigen within the tumor microenvironment (TME). A series of recent studies have highlighted that the TME poses significant metabolic challenges to TILs, which may contribute to their functional exhaustion. Hypoxia increases the expression of coinhibitors on activated CD8(+) T cells, which in general reduces the T cells' effector functions. It also impairs the cells' ability to gain energy through oxidative phosphorylation. Glucose limitation increases the expression of programed cell death protein-1 and reduces functions of activated CD8(+) T cells. A combination of hypoxia and hypoglycemia, as is common in solid tumors, places CD8(+) TILs at dual metabolic jeopardy by affecting both major pathways of energy production. Recently, a number of studies addressed the effects of metabolic stress on modulating CD8(+) T cell metabolism, differentiation, and functions. Here, we discuss recent findings on how different types of metabolic stress within the TME shape the tumor-killing capacity of CD8(+) T cells. We propose that manipulating the metabolism of TILs to more efficiently utilize nutrients, especially during intermittent periods of hypoxia could maximize their performance, prolong their survival and improve the efficacy of active cancer immunotherapy.

New insights of common gamma chain in hematological malignancies

The common gamma chain (γc) receptor family of cytokines including interleukin-2 (IL-2), IL-4, IL-7, IL-9, IL-15, and IL-21 has the common feature of sharing γc signaling subunit of their receptors. The γc cytokines have unique biological effects that regulate differentiation, survival and activation of multiple lymphocyte lineages and control proliferation of malignant cell by influencing tumor environment. It has been also described that different types of lymphoid leukemia and lymphoma exhibit expression of divergent γc cytokines and their receptors, as they may promote malignant transformation of lymphoid cells or on the contrary lead to tumor regression by inducing cell-cycle arrest. Therefore, cytokine-based or cytokine-directed blockade in cancer immunotherapy has currently revolutionized the development of cancer treatment. In this review, we will discuss about the role of γc cytokines and their signaling pathways in hematological malignancies and also propose a novel alternative approach that regulates γc cytokine responsiveness by γc in hematological malignancies.

Common gamma chain cytokines in combinatorial immune strategies against cancer

Common γ chain (γC) cytokines, namely IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21 are important for the proliferation, differentiation, and survival of lymphocytes that display antitumor activity, thus stimulating considerable interest for the use of cytokines in cancer immunotherapy. In this review, we will focus on the γC cytokines that demonstrate the greatest potential for immunotherapy, IL-2, IL-7, IL-15, and IL-21. We will briefly cover their biological function, potential applications in cancer therapy, and update on their use in combinatorial immune strategies for eradicating tumors and hematopoietic malignancies.

In-vitro activation of natural killer cells from regional lymph nodes of melanoma patients with interleukin-2 and interleukin-15

Regional lymph nodes (LNs) represent the first barrier in lymphogenic tumor dissemination in melanoma. Natural killer (NK) cells, the effector cell subpopulation of the innate immune system, are in the first line of antitumor immune defense. Therefore, the aim of this study was to investigate the effect of interleukin (IL)-2 and IL-15, two cytokines with similar immune-enhancing effects, on antitumor cytotoxic function and immunophenotype of NK cells from regional LNs of melanoma patients. Mononuclear cells purified from regional LNs of 50 melanoma patients in clinical stage II-IV were treated in vitro for 72 h and 7 days with 200 IU/ml rhIL-2 and 25 ng/ml IL-15 at 37°C in 5% CO2. Both cytokines significantly augmented NK cell cytotoxic activity, transcription of the cytotoxic molecule perforin, and the level of functionally mature perforin in both nonmetastatic and metastatic regional LNs. IL-2 treatment increased the percentage of CD3CD56 NK cells by increasing the CD56 NK cell subset in both nonmetastatic and metastatic LNs, whereas IL-15 treatment did not affect the percentage of NK cells and their subsets. Both cytokines increased on NK cells from nonmetastatic and metastatic LNs the expression of CD69 early activation antigen, the NKG2D activating receptor, as well as CD16 and inhibitory killer-cell immunoglobulin-like receptor CD158b, both inherent to the mature and the cytotoxic NK cell phenotype. In conclusion, our data may indicate the therapeutic potential of the NK cell population from regional LNs either as immunotherapeutic targets or as adoptively transferred after activation with IL-2 or IL-15.

Concepts of immunotherapy for glioma

Immunotherapy is coming to the fore as a viable anti-cancer treatment modality, even in poorly immunogenic cancers such as glioblastoma (GBM). Accumulating evidence suggests that the central nervous system may not be impervious to tumor-specific immune cells and could be an adequate substrate for immunologic anti-cancer therapies. Recent advances in antigen-specific cancer vaccines and checkpoint blockade in GBM provide promise for future immunotherapy in glioma. As anti-GBM immunotherapeutics enter clinical trials, it is important to understand the interactions, if any, between immune-based treatment modalities and the current standard of care for GBM involving chemoradiation and steroid therapy. Current data suggests that chemoradiation may not preclude the success of immunotherapeutics, as their effects may be synergistic. The future of therapy for GBM lies in the power of combination modalities, involving immunotherapy and the current standard of care.

Targeting T cell metabolism for therapy

In the past several years a wealth of evidence has emerged illustrating how metabolism supports many aspects of T cell biology, as well as how metabolic changes drive T cell differentiation and fate. We outline developing principles in the regulation of T cell metabolism, and discuss how these processes are affected in settings of inflammation and cancer. In this context we discuss how metabolic pathways might be manipulated for the treatment of human disease, including how metabolism may be targeted to prevent T cell dysfunction in inhospitable microenvironments, to generate more effective adoptive cellular immunotherapies in cancer, and to direct T cell differentiation and function towards non-pathogenic phenotypes in settings of autoimmunity.

The future of glioblastoma therapy: synergism of standard of care and immunotherapy

The current standard of care for glioblastoma (GBM) is maximal surgical resection with adjuvant radiotherapy and temozolomide (TMZ). As the 5-year survival with GBM remains at a dismal <10%, novel therapies are needed. Immunotherapies such as the dendritic cell (DC) vaccine, heat shock protein vaccines, and epidermal growth factor receptor (EGFRvIII) vaccines have shown encouraging results in clinical trials, and have demonstrated synergistic effects with conventional therapeutics resulting in ongoing phase III trials. Chemoradiation has been shown to have synergistic effects when used in combination with immunotherapy. Cytotoxic ionizing radiation is known to trigger pro-inflammatory signaling cascades and immune activation secondary to cell death, which can then be exploited by immunotherapies. The future of GBM therapeutics will involve finding the place for immunotherapy in the current treatment regimen with a focus on developing strategies. Here, we review current GBM therapy and the evidence for combination of immune checkpoint inhibitors, DC and peptide vaccines with the current standard of care.

Cytokine-like molecule CCDC134 contributes to CD8⁺ T-cell effector functions in cancer immunotherapy

CCDC134 is a poorly characterized secreted protein that may act as an immune cytokine. Here, we show that CCDC134 is differentially expressed on resting and activated immune cells and that it promotes CD8(+) T-cell activation, proliferation, and cytotoxicity by augmenting expression of the T-cell effector molecules IFNγ, TNFα, granzyme B, and perforin. CCDC134 facilitated infiltration of CD8(+) T cells with enhanced cytolytic activity into tumors, demonstrating strong antitumor effects in a CD8(+) T-cell-dependent manner. Mechanistically, in CD8(+) T cells, exposure to CCDC134 promoted cell proliferation through the JAK3-STAT5 pathway, a classic feature of many cytokines of the common γ-chain (γ(c)) cytokine receptor family. Overall, our results provide evidence that CCDC134 may serve as a member of the γ(c) cytokine family and illustrate its potent antitumor effects by augmenting CD8(+) T-cell-mediated immunity.

Antibody-cytokine fusion proteins for treatment of cancer: engineering cytokines for improved efficacy and safety

The true potential of cytokine therapies in cancer treatment is limited by the inability to deliver optimal concentrations into tumor sites due to dose-limiting systemic toxicities. To maximize the efficacy of cytokine therapy, recombinant antibody-cytokine fusion proteins have been constructed by a number of groups to harness the tumor-targeting ability of monoclonal antibodies. The aim is to guide cytokines specifically to tumor sites where they might stimulate more optimal anti-tumor immune responses while avoiding the systemic toxicities of free cytokine therapy. Antibody-cytokine fusion proteins containing interleukin (IL)-2, IL-12, IL-21, tumor necrosis factor (TNF)α, and interferons (IFNs) α, β, and γ have been constructed and have shown anti-tumor activity in preclinical and early-phase clinical studies. Future priorities for development of this technology include optimization of tumor targeting, bioactivity of the fused cytokine, and choice of appropriate agents for combination therapies. This review is intended to serve as a framework for engineering an ideal antibody-cytokine fusion protein, focusing on previously developed constructs and their clinical trial results.

Engineered fusokine GIFT4 licenses the ability of B cells to trigger a tumoricidal T-cell response

Engineered chimeric cytokines can generate gain-of-function activity in immune cells. Here, we report potent antitumor activity for a novel fusion cytokine generated by N-terminal coupling of GM-CSF to IL4, generating a fusokine termed GIFT4. B cells treated with GIFT4 clustered GM-CSF and IL4 receptors on the cell surface and displayed a pan-STAT hyperphosphorylation associated with acquisition of a distinct phenotype and function described to date. In C57BL/6J mice, administration of GIFT4 expanded endogenous B cells and suppressed the growth of B16F0 melanoma cells. Furthermore, B16F0 melanoma cells engineered to secrete GIFT4 were rejected immunologically in a B-cell-dependent manner. This effect was abolished when GIFT4-expressing B16F0 cells were implanted in B-cell-deficient mice, confirming a B-cell-dependent antitumor effect. Human GIFT4-licensed B cells primed cytotoxic T cells and specifically killed melanoma cells in vitro and in vivo. Taken together, our results demonstrated that GIFT4 could mediate expansion of B cells with potent antigen-specific effector function. GIFT4 may offer a novel immunotherapeutic tool and define a previously unrecognized potential for B cells in melanoma immunotherapy.

IL-21 promotes CD4 T cell responses by phosphatidylinositol 3-kinase-dependent upregulation of CD86 on B cells

The cytokine IL-21 is a potent immune modulator with diverse mechanisms of action on multiple cell types. IL-21 is in clinical use to promote tumor rejection and is an emerging target for neutralization in the setting of autoimmunity. Despite its clinical potential, the biological actions of IL-21 are not yet fully understood and the full range of effects of this pleiotropic cytokine are still being uncovered. In this study, we identify a novel role for IL-21 as an inducer of the costimulatory ligand CD86 on B lymphocytes. CD86 provides critical signals through T cell-expressed CD28 that promote T cell activation in response to Ag engagement. Expression levels of CD86 are tightly regulated in vivo, being actively decreased by regulatory T cells and increased in response to pathogen-derived signals. In this study, we demonstrate that IL-21 can trigger potent and sustained CD86 upregulation through a STAT3 and PI3K-dependent mechanism. We show that elevated CD86 expression has functional consequences for the magnitude of CD4 T cell responses both in vitro and in vivo. These data pinpoint CD86 upregulation as an additional mechanism by which IL-21 can elicit immunomodulatory effects.

ESAT-6-gpi DNA vaccine augmented the specific antitumour efficacy induced by the tumour vaccine B16F10-ESAT-6-gpi/IL-21 in a mouse model

In this study, we hypothesized that the mice immunized with the glycosylphosphatidylinositol (GPI) anchored 6-kDa early-secreted antigenic target (ESAT-6) DNA vaccine (ESAT-6-gpi) and the tumour vaccine B16F10-ESAT-6-gpi/IL-21 might significantly enhance immune responses and antimelanoma efficacy. Our experimental results indicated that the anti-ESAT-6 antibody induced by the DNA vaccine ESAT-6-gpi bound ESAT-6 to the surface of tumour vaccine to activate a complement classical pathway and resulted in the B16F10 tumour cell lysis and apoptosis, which served as a potential trigger for breaking melanomatous immune tolerance to elicit an initiation of natural antimelanoma immunity. Our innovative approach of using the DNA vaccine ESAT-6-gpi priming and the tumour vaccine B16F10-ESAT-6-gpi/IL-21 boosting induced strong antimelanoma immunity that inhibited melanomatous growth. These findings highlighted the DNA vaccine ESAT-6-gpi as an immune enhancer to augment the immune efficacy of the tumour vaccine B16F10-ESAT -6-gpi/IL-21 against melanoma in a mouse model.

Prospects of combinatorial synthetic peptide vaccine-based immunotherapy against cancer

The insight that the immune system is involved in tumor resistance is gaining momentum and this has led to the development of immunotherapeutic strategies aiming at enhancement of immune-mediated tumor destruction. Although some of these strategies have moderate clinical benefit, most stand-alone therapies fail to significantly affect progressive disease and survival or do so only in a minority of patients. Research on the mechanisms underlying the generation of immune responses against tumors and the immune evasion by tumors has emphasized that various mechanisms simultaneously prevent effective immunity against cancer including inefficient presentation of tumor antigens by dendritic cells and induction of negative immune regulation by regulatory T-cells (Tregs) and myeloid derived suppressor cells (MDSCs). Thus the design of therapies that simultaneously improve effective tumor immunity and counteract immune evasion by tumors seems most desirable for clinical efficacy. As it is unlikely that a single immunotherapeutic strategy addresses all necessary requirements, combinatorial strategies that act synergistically need to be developed. Here we discuss the current knowledge and prospects of treatment with synthetic peptide vaccines that stimulate tumor-specific T-cell responses combined with adjuvants, immune modulating antibodies, cytokines and chemotherapy. We conclude that combinatorial approaches have the best potency to accomplish the most significant tumor destruction but further research is required to optimize such approaches.

Immunotherapeutic applications of IL-15

IL-15 is a member of the IL-2 family of cytokines, which play a fundamental role in innate and adaptive immune responses. IL-15 has pleiotropic immune-enhancing activities, as it stimulates NK, T and NKT cell proliferation, survival and effector functions. In view of these properties, IL-15 is regarded as a good candidate for cancer immunotherapy. This possibility is reinforced by its low toxicity and efficacy in preclinical tumor models. The use of IL-15 to boost the immune response in HIV infection has also been proposed, although further studies are required to establish potential risks and benefits. Clinical trials of IL-15 have been initiated in cancer patients and in HIV vaccination and will elucidate the potential of IL-15-based immunotherapy. The purpose of this review is to provide an update on the potential applications of IL-15 in cancer immunotherapy and HIV infection.

Increased cytotoxic capacity of tumor antigen specific human T cells after in vitro stimulation with IL21 producing dendritic cells

Monocyte derived dendritic cells (moDC) electroporated with tumor associated antigen derived mRNA can elicit specific T cells against tumor cells in vivo. IL21 has been shown to enhance activation and cytotoxicity in CD8+ T cells. We therefore investigated in vitro effects on human CD8+ T-cells after stimulation with IL21 mRNA electroporated moDC. Codon modification of the IL21 gene significantly enhanced IL21 production upon electroporation of moDC. Tumor associated antigen specific CTL induction efficiency was significantly enhanced when codon modified IL21 mRNA was co-electroporated with tumor associated antigen mRNA. Tumor associated antigen specific T cells induced by codon modified IL21-DC demonstrated increased cytotoxic capacity and killing compared to control cultures. In conclusion, ectopic expression of codon modified IL21 by moDC enhances the priming efficiency of the DC as well as the cytotoxic potential of the induced CTL.

Interleukin-7, but not thymic stromal lymphopoietin, plays a key role in the T cell response to influenza A virus

The immune response to viral infection is ideally rapid and specific, resulting in viral clearance and establishment of immune memory. Some viruses such as HIV can evade such responses leading to chronic infection, while others like Influenza A can elicit a severe inflammatory response with immune-related complications including death. Cytokines play a major role in shaping the appropriate outcomes to infection. While Interleukin-7 (IL-7) has a critical role in T and B cell development, treatment with IL-7 has recently been shown to aid the adaptive T cell response in clearance of chronic viral infection. In contrast, the IL-7-related cytokine thymic stromal lymphopoietin (TSLP) has a limited role in lymphocyte development but is important in the immune response to parasitic worms and allergens. The role for these cytokines in the immune response to an acute viral infection is unclear. IL-7 and TSLP share IL-7Rα as part of their heterodimeric receptors with the gamma common chain (γc) and TSLPR, respectively. We investigated the role of IL-7 and TSLP in the primary immune response to influenza A infection using hypomorphic IL-7Rα (IL-7Rα^449F) and TSLPR^−/− mice. We found that IL-7, but not TSLP, plays an important role in control of influenza A virus. We also showed that IL-7 signaling was necessary for the generation of a robust influenza A-specific CD4 and CD8 T cell response and that this requirement is intrinsic to CD8 T cells. These findings demonstrate a significant role for IL-7 during acute viral infection.

Abrogation of SRC homology region 2 domain-containing phosphatase 1 in tumor-specific T cells improves efficacy of adoptive immunotherapy by enhancing the effector function and accumulation of short-lived effector T cells in vivo

T cell expression of inhibitory proteins can be a critical component for the regulation of immunopathology owing to self-reactivity or potentially exuberant responses to pathogens, but it may also limit T cell responses to some malignancies, particularly if the tumor Ag being targeted is a self-protein. We found that the abrogation of Src homology region 2 domain-containing phosphatase-1 (SHP-1) in tumor-reactive CD8(+) T cells improves the therapeutic outcome of adoptive immunotherapy in a mouse model of disseminated leukemia, with benefit observed in therapy employing transfer of CD8(+) T cells alone or in the context of also providing supplemental IL-2. SHP-1(-/-) and SHP-1(+/+) effector T cells were expanded in vitro for immunotherapy. Following transfer in vivo, the SHP-1(-/-) effector T cells exhibited enhanced short-term accumulation, followed by greater contraction, and they ultimately formed similar numbers of long-lived, functional memory cells. The increased therapeutic effectiveness of SHP-1(-/-) effector cells was also observed in recipients that expressed the tumor Ag as a self-antigen in the liver, without evidence of inducing autoimmune toxicity. SHP-1(-/-) effector CD8(+) T cells expressed higher levels of eomesodermin, which correlated with enhanced lysis of tumor cells. Furthermore, reduction of SHP-1 expression in tumor-reactive effector T cells by retroviral transduction with vectors that express SHP-1-specific small interfering RNA, a translatable strategy, also exhibited enhanced antitumor activity in vivo. These studies suggest that abrogating SHP-1 in effector T cells may improve the efficacy of tumor elimination by T cell therapy without affecting the ability of the effector cells to persist and provide a long-term response.

Umbilical cord blood immunology: relevance to stem cell transplantation

Because of its easier accessibility and less severe graft-versus-host disease, umbilical cord blood (UCB) has been increasingly used as an alternative to bone marrow for hematopoietic stem cell transplantation. Naiveté of UCB lymphocytes, however, results in delayed immune reconstitution and infection-related mortality in transplant recipients. This review updates the phenotypic and functional deficiencies of various immune cell populations in UCB compared with their adult counterparts and discusses clinical implications and possible therapeutic strategies to improve the outcome of stem cell transplantation.

IL-21 inhibits T cell IL-2 production and impairs Treg homeostasis

Modulation of regulatory T cell (Treg) suppression has important implications for vaccine development, the effectiveness of tumor surveillance, and the emergence of autoimmunity. We have previously shown that the cytokine IL-21 can counteract Treg suppression. However, whether this reflects an effect of IL-21 on Treg, conventional T cells, or antigen-presenting cells is not known. Here we have used lymphocyte populations from IL-21R–deficient mice to pinpoint which cell type needs to be targeted by IL-21 for Treg suppression to be overcome. We show that IL-21 counteracts suppression by acting on conventional T cells and that this is associated with inhibition of IL-2 production. Despite the lack of IL-2, conventional T-cell responses proceed unimpaired because IL-21 can substitute for IL-2 as a T cell growth factor. However, IL-21 is unable to substitute for IL-2 in supporting the Treg compartment. Thus, IL-21 signaling in conventional T cells indirectly impacts Treg homeostasis by decreasing IL-2 availability. These data demonstrate that IL-21 and IL-2 can have overlapping roles in promoting conventional T-cell responses but play distinct roles in controlling Treg homeostasis and function. The data also suggest a new paradigm whereby cytokines can promote immunity by inhibiting IL-2.

Natural killer cell engineering for cellular therapy of cancer

Natural killer (NK) cells can kill transformed cells and represent a promising tool for the treatment of cancer. Their function is governed by a balance of stimulatory and inhibitory signals triggered by surface receptors. Advances in NK cell therapy require the development of dependable methods for obtaining an adequate number of effector cells; additional activation or genetic modification may further increase their anticancer capacity. A method for NK cell expansion used in our laboratory relies on a genetically modified form of the K562 myeloid leukemia cell line, engineered to express a membrane-bound form of interleukin-15 and the ligand for the costimulatory molecule 4-1BB (CD137). Expanded NK cells can be transduced with genes encoding chimeric antigen receptors that stimulate tumor cell-specific cytotoxicity. These methods for NK cell expansion and genetic modification have been adapted to large-scale, clinical-grade, Current Good Manufacturing Practice conditions and support two active clinical trials. Summarized are current efforts for NK cell immunotherapy for cancer and future perspectives.

Regulation of CD28 expression on umbilical cord blood and adult peripheral blood CD8+ T cells by interleukin(IL)-15/IL-21

Interleukin (IL)-15 and IL-21, both belonging to common γ-chain-signaling cytokine family, have an important role to maintain homeostatic proliferation of CD8(+) T cells. CD28, an essential co-stimulatory molecule on T cells, may be a marker of replicative senescence. We investigated the effect of IL-15 and IL-21, alone or in combination, on activation, apoptosis, cytokine production and cytotoxic function of magnetic bead purified umbilical cord blood (UCB) and adult peripheral blood (APB) CD8(+) T cells with regards to their CD28 expression. We established that (1) IL-15-induced CD8(+) T cell proliferation was associated with a preferential expansion of CD28(-) population in UCB, which could be partially counteracted by IL-21; (2) UCB CD8(+) T cells were more readily responsive to IL-15 compared to their adult counterparts in terms of CD69 expression, with the majority of CD69-bearing CD8(+) T cells were CD28(-); (3) IL-21 further promoted interferon-gamma, but not tumor necrosis factor-alpha production from IL-15 treated CD8(+) T cells; (4) IL-21 also synergized with IL-15 to enhance perforin and granzyme B expression of CD8(+) T cells, especially in APB CD8(+)CD28(-) subsets; (5) IL-21 resulted in CD8(+) T cells apoptosis both in APB and UCB cells, mainly in CD8(+)CD28(-) subsets. Taken together, we demonstrate differential IL-15/IL-21 response in UCB CD8(+) T cells with regards to CD28 expression. Our results suggest that combining IL-21 and IL-15 immunotherapy may be better than IL-15 alone to ameliorate graft-versus-host disease while preserving antitumor effect in the post-UCB transplantation period.

IL-15 administered by continuous infusion to rhesus macaques induces massive expansion of CD8+ T effector memory population in peripheral blood

IL-15 promotes activation and maintenance of natural killer (NK) and CD8(+) T effector memory (T(EM)) cells, making it a potential immunotherapeutic agent for the treatment of cancer and immunodeficiency states. Here we report the immunologic effects of 3 different IL-15 dosing strategies in Rhesus macaques. IL-15 at a dose of 20 μg/kg/d administered by continuous intravenous infusion for 10 days resulted in a massive (100-fold) expansion of CD8(+) T(EM) cells in the peripheral blood. In contrast, the administration of 20-40 μg/kg/d of IL-15 by subcutaneous injection resulted in a more modest (10-fold) expansion of CD8(+) T(EM) cells. NK expansion was similar in both the continuous intravenous and daily subcutaneous treatment groups. The observation that IL-15 administered by continuous intravenous infusion is able to induce markedly greater expansions of CD8(+) T(EM) cells than the same dose administered by other routes may have important implications for clinical development of this cytokine.

Cancer immunotherapy comes of age

Cancer immunotherapy comprises a variety of treatment approaches, incorporating the tremendous specificity of the adaptive immune system (T cells and antibodies) as well as the diverse and potent cytotoxic weaponry of both adaptive and innate immunity. Immunotherapy strategies include antitumor monoclonal antibodies, cancer vaccines, adoptive transfer of ex vivo activated T and natural killer cells, and administration of antibodies or recombinant proteins that either costimulate immune cells or block immune inhibitory pathways (so-called immune checkpoints). Although clear clinical efficacy has been demonstrated with antitumor antibodies since the late 1990s, other immunotherapies had not been shown to be effective until recently, when a spate of successes established the broad potential of this therapeutic modality. These successes are based on fundamental scientific advances demonstrating the toleragenic nature of cancer and the pivotal role of the tumor immune microenvironment in suppressing antitumor immunity. New therapies based on a sophisticated knowledge of immune-suppressive cells, soluble factors, and signaling pathways are designed to break tolerance and reactivate antitumor immunity to induce potent, long-lasting responses. Preclinical models indicate the importance of a complex integrated immune response in eliminating established tumors and validate the exploration of combinatorial treatment regimens, which are anticipated to be far more effective than monotherapies. Unlike conventional cancer therapies, most immunotherapies are active and dynamic, capable of inducing immune memory to propagate a successful rebalancing of the equilibrium between tumor and host.

Characterization of recombinant human IL-15 deamidation and its practical elimination through substitution of asparagine 77

PURPOSE

The use of recombinant human interleukin (rhIL)-15 as a potential therapeutic immune modulator and anticancer agent requires pure, stable preparations. However, purified rhIL-15 preparations readily accumulated heterogeneities. We sought to improve rhIL-15 stability through process, formulation, and targeted amino acid changes.

METHODS

The solution state of rhIL-15 versus buffer composition and temperature was studied using SEC and IEX methods. rhIL-15 deamidation was confirmed using RP-HPLC/ESI-MS, enzymatic labeling, and peptide mapping. Deamidation kinetics were measured versus buffer composition and pH using RP-HPLC. Deamidation-resistant rhIL-15 variants (N77A, N77S, N77Q, G78A, and [N71S/N72A/N77A]) were produced in E. coli, then assayed for T-cell culture expansion potency and deamidation resistance.

RESULTS

Adding 20% ethanol to buffers or heating at ≥32°C dispersed rhIL-15 transient pairs, improving purification efficiencies. Asparagine 77 deamidated rapidly at pH 7.4 with activation energy of 22.9 kcal per mol. Deamidation in citrate buffer was 17-fold slower at pH 5.9 than at pH 7.4. Amino acid substitutions at N77 or G78 slowed deamidation ≥23-fold. rhIL-15 variants N77A and (N71S/N72A/N77A) were active in a CTLL-2 proliferation assay equivalent to unsubstituted rhIL-15.

CONCLUSIONS

The N77A and (N71S/N72A/N77A) rhIL-15 variants are resistant to deamidation and remain potent, thus providing enhanced drug substances for clinical evaluation.

Elevated levels of circulating IL-7 and IL-15 in patients with early stage prostate cancer

Background

Chronic inflammation has been suggested to favour prostate cancer (PCA) development. Interleukins (IL) represent essential inflammation mediators. IL-2, IL-7, IL-15 and IL-21, sharing a common receptor γ chain (c-γ), control T lymphocyte homeostasis and proliferation and play major roles in regulating cancer-immune system interactions. We evaluated local IL-2, IL-7, IL-15 and IL-21 gene expression in prostate tissues from patients with early stage PCA or benign prostatic hyperplasia (BPH). As control, we used IL-6 gene, encoding an IL involved in PCA progression. IL-6, IL-7 and IL-15 titres were also measured in patients' sera.

Methods

Eighty patients with BPH and 79 with early (1 to 2c) stage PCA were enrolled. Gene expression in prostate tissues was analyzed by quantitative real-time PCR (qRT-PCR). Serum IL concentrations and acute phase protein titres were evaluated by ELISA. Mann-Whitney, Wilcoxon and χ² tests were used to compare IL gene expression and serum titers in the two groups of patients. Receiver operating characteristic (ROC) curves were constructed to evaluate the possibility to distinguish sera from different groups of patients based on IL titers.

Results

IL-2 and IL-21 gene expression was comparably detectable, with low frequency and at low extents, in PCA and BPH tissues. In contrast, IL-6, IL-7 and IL-15 genes were expressed more frequently (p < 0.0001, p = 0.0047 and p = 0.0085, respectively) and to significantly higher extents (p = 0.0051, p = 0.0310 and p = 0.0205, respectively) in early stage PCA than in BPH tissues. Corresponding proteins could be detected to significantly higher amounts in sera from patients with localized PCA, than in those from patients with BPH (p = 0.0153, p = 0.0174 and p = 0.0064, respectively). Analysis of ROC curves indicates that IL-7 (p = 0.0039), but not IL-6 (p = 0.2938) or IL-15 (p = 0.1804) titres were able to distinguish sera from patients with malignancy from those from patients with benign disease. Serum titres of C reactive (CRP), high mobility group B1 (HMGB1) and serum amyloid A (SAA) acute phase proteins were similar in both groups of patients.

Conclusions

Expression IL-7 and IL-15 genes in prostate tissues and corresponding serum titres are significantly increased in patients with early stage PCA as compared with patients with BPH.

Identification of outcome-correlated cytokine clusters in chronic lymphocytic leukemia

Individual cytokines and groups of cytokines that might represent networks in chronic lymphocytic leukemia (CLL) were analyzed and their prognostic values determined. Serum levels of 23 cytokines were measured in 84 patients and 49 age-matched controls; 17 levels were significantly elevated in patients. Unsupervised hierarchical bicluster analysis identified 3 clusters (CLs) of highly correlated but differentially expressed cytokines: CL1 (CXCL9, CXCL10, CXCL11, CCL3, CCL4, CCL19, IL-5, IL-12, and IFNγ), CL2 (TNFα, IL-6, IL-8, and GM-CSF), and CL3 (IL-1β, IL-2, IL-4, IL-15, IL-17, and IFNα). Combination scores integrating expression of CL1/CL2 or CL1/CL3 strongly correlated (P < .005) with time-to-first-treatment and overall survival (OS), respectively. Patients with the worst course had high CL1 and low CL2 or CL3 levels. Multivariate analysis revealed that CL1/CL2 combination score and immunoglobulin heavy chain variable region mutation status were independent prognostic indicators for time-to-first-treatment, whereas CL1/CL3 combination score and immunoglobulin heavy chain variable region mutation status were independent markers for OS. Thus, we identified groups of cytokines differentially expressed in CLL that are independent prognostic indicators of aggressive disease and OS. These findings indicate the value of multicytokine analyses for prognosis and suggest therapeutic strategies in CLL aimed at reducing CL1 and increasing CL2/CL3 cytokines.

IFN-α primes T- and NK-cells for IL-15-mediated signaling and cytotoxicity

Recently it has become clear that interferon (IFN)-α, a type I interferon produced rapidly in response to infection, not only plays a key role in innate immunity, but also promotes adaptive immune responses by influencing the production or function of other cytokines. During infections IFN-α fosters the production of IL-15, which plays a pivotal role in the development, survival and function of NK cells and recruitment and activation of T cells. Since these two cytokines exert overlapping functions during infections, this investigation was undertaken to study the priming effect of IFN-α on the effect of IL-15 on human T and NK cells. We show that IFN-α induces an increased expression of IL-15Rα in human activated peripheral T cells, and in CD8(+) and CD4(+) T-cell lines. Functionally, the IFN-α-enhanced IL-15Rα expression resulted in an enhanced IL-15-mediated phosphorylation of STAT5 and STAT3 followed by a further increase in IL-15Rα expression. Moreover, IFN-α significantly increased the IL-15-induced cytotoxic activity of freshly isolated T and NK cells. Taken together, our data show that IFN-α boosts signaling and functional effects of IL-15, at least in part by fostering the increased IL-15R expression, thus add new facet to the emerging role of IFN-α as an important primer of adaptive immune responses.

Harnessing the biology of IL-7 for therapeutic application

Interleukin-7 (IL-7) is required for T cell development and for maintaining and restoring homeostasis of mature T cells. IL-7 is a limiting resource under normal conditions, but it accumulates during lymphopaenia, leading to increased T cell proliferation. The administration of recombinant human IL-7 to normal or lymphopenic mice, non-human primates and humans results in widespread T cell proliferation, increased T cell numbers, modulation of peripheral T cell subsets and increased T cell receptor repertoire diversity. These effects raise the prospect that IL-7 could mediate therapeutic benefits in several clinical settings. This Review summarizes the biology of IL-7 and the results of its clinical use that are available so far to provide a perspective on the opportunities for clinical application of this cytokine.

Role of common-gamma chain cytokines in NK cell development and function: perspectives for immunotherapy

NK cells are components of the innate immunity system and play an important role as a first-line defense mechanism against viral infections and in tumor immune surveillance. Their development and their functional activities are controlled by several factors among which cytokines sharing the usage of the common cytokine-receptor gamma chain play a pivotal role. In particular, IL-2, IL-7, IL-15, and IL-21 are the members of this family predominantly involved in NK cell biology. In this paper, we will address their role in NK cell ontogeny, regulation of functional activities, development of specialized cell subsets, and acquisition of memory-like functions. Finally, the potential application of these cytokines as recombinant molecules to NK cell-based immunotherapy approaches will be discussed.

Immunomodulatory cytokines as therapeutic agents for melanoma

Melanoma is the most aggressive form of skin cancer whose worldwide incidence is rising faster than any other cancer. Few treatment options are available to patients with metastatic disease, and standard chemotherapeutic agents are generally ineffective. Cytokines such as IFN-α or IL-2 can promote immune recognition of melanoma, occasionally inducing dramatic and durable clinical responses. Here, we discuss several immunomodulatory agents, the safety of which are being evaluated in clinical trials. Challenges include an incomplete understanding of signaling pathways, appropriate clinical dose and route, and systemic immunosuppression in advanced melanoma patients. We consider how targeted cytokine therapy will integrate into the clinical arena, as well as the low likelihood of success of single cytokine therapies. Evidence supports a synergy between cytokine immunotherapy and other therapeutic approaches in melanoma, and strengthening this area of research will improve our understanding of how to use cytokine therapy better.