Interleukin-2 administration alters the CD4+FOXP3+ T-cell pool and tumor trafficking in patients with ovarian carcinoma

Modulation of biomaterial-induced foreign body response by regulating the differentiation and migration of Treg cells through the CXCL12-CXCR4/7 axis

Tissue exposure to implanted biomaterials triggers a foreign body response (FBR), which is a stepwise immunological process involving innate immune cells and tissue repair cells. Although the regulatory T (Treg) cells play a crucial role in inflammation and tissue repair, their function in the process of FBR has not been well investigated. In this study, as titanium (Ti) exhibits better biocompatibility and induces milder FBR than polymethyl methacrylate (PMMA), we analyzed the characteristics of Treg cells during FBR caused by the two types of biomaterials. In a rat femur implantation model, we found that the number of Treg cells around titanium implants was much more than that in the PMMA-implanted group. Meanwhile, the expression of CXCR4 in tissues around Ti implants was significantly higher, and the expression of CXCR7 was lower. When co-cultured with biomaterials and macrophages, the differentiation and migration of Treg cells in the Ti-implanted group were promoted, and this effect could be modulated by CXCR4/7 inhibitors. Moreover, targeting CXCR4/7 influenced the amount of Treg cells in vivo and then reversed the FBR induced by PMMA or Ti implants. In summary, our findings revealed the role of CXCR4/CXCR7 in regulating the migration and differentiation of Treg cells during FBR and suggested that the CXCL12-CXCR4/CXCR7 axis may serve as a potential therapeutic target for immunomodulating foreign body response.

Recent research progress on microRNAs from mesenchymal stem cell-derived exosomes for tumor therapy: A review

ABSTRACT

Mesenchymal stem cells (MSCs) are a class of protocells that can differentiate into various cell types and have robust replication and renewal capabilities. MSCs secrete various nutritional factors to regulate the microenvironment of tumor tissues. The mechanism by which they inhibit or promote tumor growth may be closely related to MSC-derived exosomes (MSC-Exo). However, the role of MSC-Exo vesicles in tumors remains controversial. This review discusses the potential applications of microRNAs in exosomes derived from MSCs in treating tumors.

Human NK cells and cancer

The long story of NK cells started about 50 y ago with the first demonstration of a natural cytotoxic activity within an undefined subset of circulating leukocytes, has involved an ever-growing number of researchers, fascinated by the apparently easy-to-reach aim of getting a "universal anti-tumor immune tool". In fact, in spite of the impressive progress obtained in the first decades, these cells proved far more complex than expected and, paradoxically, the accumulating findings have continuously moved forward the attainment of a complete control of their function for immunotherapy. The refined studies of these latter years have indicated that NK cells can epigenetically calibrate their functional potential, in response to specific environmental contexts, giving rise to extraordinarily variegated subpopulations, comprehensive of memory-like cells, tissue-resident cells, or cells in various differentiation stages, or distinct functional states. In addition, NK cells can adapt their activity in response to a complex body of signals, spanning from the interaction with either suppressive or stimulating cells (myeloid-derived suppressor cells or dendritic cells, respectively) to the engagement of various receptors (specific for immune checkpoints, cytokines, tumor/viral ligands, or mediating antibody-dependent cell-mediated cytotoxicity). According to this picture, the idea of an easy and generalized exploitation of NK cells is changing, and the way is opening toward new carefully designed, combined and personalized therapeutic strategies, also based on the use of genetically modified NK cells and stimuli capable of strengthening and redirecting their effector functions against cancer.

Murine models to study human NK cells in human solid tumors

Since the first studies, the mouse models have provided crucial support for the most important discoveries on NK cells, on their development, function, and circulation within normal and tumor tissues. Murine tumor models were initially set to study murine NK cells, then, ever more sophisticated human-in-mice models have been developed to investigate the behavior of human NK cells and minimize the interferences from the murine environment. This review presents an overview of the models that have been used along time to study NK cells, focusing on the most popular NOG and NSG models, which work as recipients for the preparation of human-in-mice tumor models, the study of transferred human NK cells, and the evaluation of various enhancers of human NK cell function, including cytokines and chimeric molecules. Finally, an overview of the next generation humanized mice is also provided along with a discussion on how traditional and innovative in-vivo and in-vitro approaches could be integrated to optimize effective pre-clinical studies.

"To be or not to Be": Regulatory T cells in melanoma

In spite of progresses in the therapy of different malignancies, melanoma still remains as one of lethal types of skin tumor. Melanoma is almost easily treatable by surgery alone with higher overall survival rates when it is diagnosed at early stages. However, survival rates are decreased remarkably upon survival if the tumor is progressed to advanced metastatic stages. Immunotherapeutics have been prosperous in the development of anti-tumor responses in patients with melanoma through promotion of the tumor-specific effector T cells in vivo; nonetheless, suitable clinical outcomes have not been satisfactory. One of the underlying causes of the unfavorable clinical outcomes might stem from adverse effects of regulatory T (Treg) cell, which is a prominent mechanism of tumor cells to escape from tumor-specific immune responses. Evidence shows that a poor prognosis and low survival rate in patients with melanoma can be attributed to a higher Treg cell number and function in these subjects. As a result, to promote melanoma-specific anti-tumor responses, depletion of Treg cells appears to be a promising approach; even though the clinical efficacy of different approaches to attain appropriate Treg cell depletion has been inconsistent. Here in this review, the main purpose is to assess the role of Treg cells in the initiation and perpetuation of melanoma and to discuss effective strategies for Treg cell modulation with the aim of melanoma therapy.

Multicolor Light-Induced Immune Activation via Polymer Photocaged Cytokines

Cytokines act as potent, extracellular signals of the human immune system and can elicit striking treatment responses in patients with autoimmune disease, tissue damage, and cancer. Yet, despite their therapeutic potential, recombinant cytokine-mediated immune responses remain difficult to control as their administration is often systemic, whereas their intended sites of action are localized. To address the challenge of spatially and temporally constraining cytokine signals, we recently devised a strategy whereby recombinant cytokines are reversibly inactivated via chemical modification with photo-labile polymers that respond to visible LED light. Extending this approach to enable both in vivo and multicolor immune activation, here we describe a strategy whereby cytokines appended with heptamethine cyanine-polyethylene glycol are selectively re-activated ex vivo using tissue-penetrating near-infrared (NIR) light. We show that NIR LED light illumination of caged, pro-inflammatory cytokines restores cognate receptor signaling and potentiates the activity of T cell-engager cancer immunotherapies ex vivo. Using combinations of visible- and NIR-responsive cytokines, we further demonstrate multiwavelength optical control of T cell cytolysis ex vivo, as well as the ability to perform Boolean logic using multicolored light and orthogonally photocaged cytokine pairs as inputs and T cell activity as outputs. Together, this work demonstrates a novel approach to control extracellular immune cell signals using light, a strategy that in the future may improve our understanding of and ability to treat cancer and other diseases.

Signaling new therapeutic opportunities: cytokines in prostate cancer

INTRODUCTION

Despite FDA approval of sipuleucel-T in 2010, endeavors to use immune checkpoint inhibitors in unselected prostate cancer patients have not improved clinical outcomes. These efforts include studies with anti-PD1/PD-L1 and anti-CTLA-4 alone and in combination with existing standards of care. These strategies are generally T-cell centric and disregard the broader complex and pleiotropic components of the prostate cancer tumor microenvironment such as natural killer cells, myeloid-derived suppressor cells and tumor associated macrophages.

AREAS COVERED

We performed an online literature search and undertook a review of existing pre-clinical and clinical literature for cytokine-based therapy relating to prostate cancer, specifically on interleukin (IL)-2, IL-15, IL-12, IL-23, IL-8 and transforming growth factor (TGF)-β.

EXPERT OPINION

Cytokine-based therapies present an alternative immune strategy to target the pleiotropic prostate cancer tumor microenvironment beyond T-cells. Future immunotherapy strategies in prostate cancer should address these immune cell populations which may play more important roles in the prostate cancer tumor microenvironment.

A forced marriage of IL-2 and PD-1 antibody nurtures tumor-infiltrating T cells

IL-2 is a pleiotropic cytokine. In this issue of the JCI, Ren et al. report on the development of a low-affinity IL-2 paired with anti-PD-1 (PD-1-laIL-2) that reactivates intratumoral CD8+ T cells, but not CD4+ Treg cells. PD-1-laIL-2 treatment synergized with anti-PD-L1 therapy to overcome tumor resistance to immune checkpoint blockade (ICB) in tumor-bearing mice. Rejection of rechallenged tumors following PD-1-laIL-2 therapy demonstrated the establishment of a potent T cell memory response. Furthermore, PD-1-laIL-2 therapy manifested no obvious toxicity. These findings suggest the potential of PD-1-laIL-2 therapy in treating patients with cancer.

The Frontline Immunotherapy-Based Treatment of Advanced Clear Cell Renal Cell Carcinoma: Current Evidence and Clinical Perspective

Approximately 400,000 patients are diagnosed with kidney cancer annually worldwide, leading to approximately 170,000 deaths. Renal cell carcinoma (RCC) accounts for more than 90% of kidney cancers. The most common histological subtype is clear cell RCC, which is found in approximately 85% of metastatic RCC cases. The VHL-HIF-VEGF axis is well known; therefore, targeting VEGF has been the mainstay for managing advanced clear cell RCC. Recently, the treatment landscape for advanced clear cell RCC has changed extensively. In particular, immune checkpoint inhibitor-based treatment showed promising results in front-line treatment and became the standard of care. Herein, we review the current evidence on front-line treatment options and discuss the clinical and future perspective.

Research Progress on the Role of Regulatory T Cell in Tumor Microenvironment in the Treatment of Breast Cancer

The tumor microenvironment (TME) is a complex ecosystem comprised of cancer cells, stromal cells, and immune cells. Analysis of the composition of TME is essential to assess the prognosis of patients with breast cancer (BC) and the efficacy of different regimes. Treg plays a crucial role in the microenvironment of breast cancer subtypes, and its function contributes to the development and progression of BC by suppressing anti-tumor immunity directly or indirectly through multiple mechanisms. In addition, conventional treatments, such as anthracycline-based neoadjuvant chemotherapy, and neo-therapies, such as immune-checkpoint blockades, have a significant impact on the absence of Tregs in BC TME, thus gaining additional anti-tumor effect to some extent. Strikingly, Treg in BC TME revealed the predicted efficacy of some therapeutic strategies. All these results suggest that we can manipulate the abundance of Treg to achieve the ultimate effect of both conventional and novel treatments. In this review, we discuss new insights into the characteristics of Treg in BC TME, the impact of different regiments on Treg, and the possibilities of Treg as a predictive marker of efficacy for certain treatments.

Breast cancer immune microenvironment: from pre-clinical models to clinical therapies

The breast cancer tumour microenvironment (BC-TME) is characterized by significant cellular and spatial heterogeneity that has important clinical implications and can affect response to therapy. There is a growing need to develop methods that reliably quantify and characterize the BC-TME and model its composition and functions in experimental systems, in the hope of developing new treatments for patients. In this review, we examine the role of immune-activating cells (including tumour-infiltrating lymphocytes and natural killer cells) and immune inhibitory cells (including T regulatory cells, tumour-associated macrophages and myeloid-derived suppressor cells) in the BC-TME. We summarize methods being used to characterize the microenvironment, with specific attention to pre-clinical models including co-cultures, organoids, and genetically modified and humanized mouse models. Finally, we explore the implications and applications of existing preclinical data for drug development and highlight several drugs designed to alter the BC-TME in order to improve treatment outcomes for patients.

Targeting MSS colorectal cancer with immunotherapy: are we turning the corner?

INTRODUCTION

Immunotherapy with checkpoint inhibition has shown potent antitumor activity in patients with microsatellite instability (MSI) metastatic cancer. Microsatellite stable (MSS) colorectal cancer has long been considered resistant to immunotherapy.

AREAS COVERED

In this review, we provide an overview of current progress on strategies to overcome the resistance to immunotherapy in MSS colorectal cancer.

EXPERT OPINION

Emerging evidence suggest that combination of immune modulators such as regorafenib may improve the responsiveness of MSS colorectal cancer to checkpoint blockade. In addition, signs of clinical activity have also been observed in other combination strategies, such as the combination of checkpoint blockade with Stat3 inhibitor, or bispecific T-cell engagers. Nevertheless, predictive biomarkers that can identify patients who may benefit from immunotherapy are key for its implementation in clinical setting. Metastatic disease sites may predict for the response or resistance to checkpoint blockade, with liver metastases emerging as a strong predictive biomarker of lack of benefit from PD-1 targeting, even with combination therapies. Additional efforts are required to study the mechanism of resistance and to develop novel therapeutic strategies to overcome immune resistance.

ABBREVIATIONS

CEA: carcinoembryonic antigen; CR: complete response; CTLA-4: cytotoxic T-lymphocyte-associated protein 4; DCR: disease control rate; MSI-H: microsatellite instability-high; MSS: Microsatellite stable (MSS); OS: overall survival; PD-1: programmed cell death protein 1; PD-L1: programmed death-ligand receptor 1; PR: partial response; PFS: progression-free survival; SD: stable disease; TMB: tumor mutation burden; VEGFR: vascular endothelial growth factor receptor.

Tumor resident regulatory T cells

The immune system mediates powerful effector mechanisms to protect against a diversity of pathogens and equally as important regulatory functions, to limit collateral damage of inflammation, prevent misguided immune responses to "self", and promote tissue repair. Inadequate regulatory control can lead to a variety of inflammatory disorders including autoimmunity, metabolic syndrome, allergies, and progression of malignancies. Cancers evolve complex mechanisms to thwart immune eradication including coopting normal host regulatory processes. This is most evident in the analysis of tumor infiltrating lymphocytes (TILs), where a preponderance of immunosuppressive immune cells, such as regulatory T (Treg) cells are found. Treg cells express the X-chromosome linked transcription factor Foxp3 and play a crucial role in maintaining immune homeostasis by suppressing inflammatory responses in diverse biological settings. Treg cells in the tumor microenvironment promote tumor development and progression by dampening anti-tumor immune responses, directly supporting the survival of transformed cells through elaboration of growth factors, and interacting with accessory cells in tumors such as fibroblasts and endothelial cells. Current insights into the phenotype and function of tumor associated Treg cells have opened up opportunities for their selective targeting in cancer with the goal of alleviating their suppression of anti-tumor immune responses while maintaining overall immune homeostasis. Here, we review Treg cell biology in the context of the tumor microenvironment (TME), and the important role they play in cancer immunotherapy.

CTLA-4 in Regulatory T Cells for Cancer Immunotherapy

Immune checkpoint inhibitors (ICIs) have obtained durable responses in many cancers, making it possible to foresee their potential in improving the health of cancer patients. However, immunotherapies are currently limited to a minority of patients and there is a need to develop a better understanding of the basic molecular mechanisms and functions of pivotal immune regulatory molecules. Immune checkpoint cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and regulatory T (Treg) cells play pivotal roles in hindering the anticancer immunity. Treg cells suppress antigen-presenting cells (APCs) by depleting immune stimulating cytokines, producing immunosuppressive cytokines and constitutively expressing CTLA-4. CTLA-4 molecules bind to CD80 and CD86 with a higher affinity than CD28 and act as competitive inhibitors of CD28 in APCs. The purpose of this review is to summarize state-of-the-art understanding of the molecular mechanisms underlining CTLA-4 immune regulation and the correlation of the ICI response with CTLA-4 expression in Treg cells from preclinical and clinical studies for possibly improving CTLA-4-based immunotherapies, while highlighting the knowledge gap.

Metabolic reprogramming of T regulatory cells in the hypoxic tumor microenvironment

Metabolic dysregulation in the hypoxic tumor microenvironment (TME) is considered as a hallmark of solid tumors, leading to changes in biosynthetic pathways favoring onset, survival and proliferation of malignant cells. Within the TME, hypoxic milieu favors metabolic reprogramming of tumor cells, which subsequently affects biological properties of tumor-infiltrating immune cells. T regulatory cells (Tregs), including both circulating and tissue-resident cells, are particularly susceptible to hypoxic metabolic signaling that can reprogram their biological and physicochemical properties. Furthermore, metabolic reprogramming modifies Tregs to utilize alternative substrates and undergo a plethora of metabolic events to meet their energy demands. Major impact of this metabolic reprogramming can result in differentiation, survival, excessive secretion of immunosuppressive cytokines and proliferation of Tregs within the TME, which in turn dampen anti-tumor immune responses. Studies on fine-tuning of Treg metabolism are challenging due to heterogenicity of tissue-resident Tregs and their dynamic functions. In this review, we highlight tumor intrinsic and extrinsic factors, which can influence Treg metabolism in the hypoxic TME. Moreover, we focus on metabolic reprogramming of Tregs that could unveil potential regulatory networks favoring tumorigenesis/progression, and provide novel insights, including inhibitors against acetyl-coA carboxylase 1 and transforming growth factor beta into targeting Treg metabolism for therapeutic benefits.

Regulatory T cells in the bone marrow microenvironment in patients with prostate cancer

Human prostate cancer frequently metastasizes to bone marrow. What defines the cellular and molecular predilection for prostate cancer to metastasize to bone marrow is not well understood. CD4⁺CD25⁺ regulatory T (Treg) cells contribute to self-tolerance and tumor immune pathology. We now show that functional Treg cells are increased in the bone marrow microenvironment in prostate cancer patients with bone metastasis, and that CXCR4/CXCL12 signaling pathway contributes to Treg cell bone marrow trafficking. Treg cells exhibit active cell cycling in the bone marrow, and bone marrow dendritic cells express high levels of receptor activator of NFκB (RANK), and promote Treg cell expansion through RANK and its ligand (RANKL) signals. Furthermore, Treg cells suppress osteoclast differentiation induced by activated T cells and M-CSF, adoptive transferred Treg cells migrate to bone marrow, and increase bone mineral intensity in the xenograft mouse models with human prostate cancer bone marrow inoculation. In vivo Treg cell depletion results in reduced bone density in tumor bearing mice. The data indicates that bone marrow Treg cells may form an immunosuppressive niche to facilitate cancer bone metastasis and contribute to bone deposition, the major bone pathology in prostate cancer patients with bone metastasis. These findings mechanistically explain why Treg cells accumulate in the bone marrow, and demonstrate a previously unappreciated role for Treg cells in patients with prostate cancer. Thus, targeting Treg cells may not only improve anti-tumor immunity, but also ameliorate bone pathology in prostate cancer patients with bone metastasis.

Breast cancer therapy affects the expression of antineonatal Nav1.5 antibodies in the serum of patients with breast cancer

Neonatal Nav1.5 (nNav1.5) is the alternative splice variant of Nav1.5 and it has been widely associated with the progression of breast cancer. The immunological context of nNav1.5 with respect to breast cancer metastases remains unexplored. The presence of antibodies against nNav1.5 may highlight the immunogenicity of nNav1.5. Hence, the aim of the present study was to detect the presence of antineonatal Nav1.5 antibodies (antinNav1.5-Ab) in the serum of patients with breast cancer and to elucidate the effects of breast cancer therapy on its expression. A total of 32 healthy female volunteers and 64 patients with breast cancer were randomly recruited into the present study as the control and breast cancer group, respectively. Patients with breast cancer were divided equally based on their pre- and ongoing-treatment status. Serum samples were tested with in-house indirect enzyme-linked immunosorbent assay (ELISA) to detect antinNav1.5-Ab, CD25 (T regulatory cell marker) using an ELISA kit and Luminex assay to detect the expression of metastasis-associated cytokines, such as vascular endothelial growth factor (VEGF), interleukin (IL)-6, IL-10, IL-8, chemokine (C-C motif) ligand 2 and tumor necrosis factor-alpha (TNF-α) The mean difference in the expression of antinNav1.5-Ab among the three groups (control, pretreatment and ongoing-treatment) was significant (P=0.0005) and the pretreatment breast cancer group exhibited the highest expression. The concentration of CD25 was highest in the pretreatment breast cancer group compared with the control and ongoing-treatment groups. There was a significant positive correlation between antinNav1.5-Ab and IL-6 in the pretreatment group (r=0.7260; P=0.0210) and a significant negative correlation between antinNav1.5-Ab and VEGF in the ongoing-treatment group (r=-0.842; P-value=0.0040). The high expression of antinNav1.5-Ab in the pretreatment group was in accordance with the uninterrupted presence of metastasis and highlighted the immunogenicity of nNav1.5 whereas the low expression of antinNav1.5-Ab in the ongoing-treatment group reflected the efficacy of breast cancer therapy in eliminating metastases. The augmented manifestation of T regulatory cells in the pretreatment group highlighted the functional role of nNav1.5 in promoting metastasis. The parallel expression of antinNav1.5-Ab with the imbalanced expression of cytokines promoting metastasis (IL-8, IL-6 and TNF-α) and cytokines that prevent metastasis (IL-10) indicated the role of nNav1.5 in breast cancer growth. The expression of antinNav1.5-Ab in accordance to the metastatic microenvironment indicates the immunogenicity of the protein and highlights the influence of breast cancer therapy on its expression level.

The bone marrow niche components are adversely affected in sepsis

Multiple organ dysfunction is an important cause of death in patients with sepsis. Currently, few studies have focused on the impact of sepsis on bone marrow (BM), especially on the cell components of BM niche. In this study, we performed mouse sepsis models by intraperitoneal injection of LPS and cecal ligation and puncture (CLP). The changes of niche major components in the mouse BM among vascular structures, mesenchymal stem cells and Treg cells were observed and analyzed. The results showed that pathological changes in BM was earlier and more prominent than in other organs, and various cell components of the BM niche changed significantly, of which vascular endothelial cells increased transiently with vascular remodeling and the regulatory T cells decreased over a long period of time. These results indicated that the components of the BM niche underwent series of adaptive changes in sepsis.

CD122-Selective IL2 Complexes Reduce Immunosuppression, Promote Treg Fragility, and Sensitize Tumor Response to PD-L1 Blockade

The IL2 receptor (IL2R) is an attractive cancer immunotherapy target that controls immunosuppressive T regulatory cells (Treg) and antitumor T cells. Here we used IL2Rβ-selective IL2/anti-IL2 complexes (IL2c) to stimulate effector T cells preferentially in the orthotopic mouse ID8agg ovarian cancer model. Despite strong tumor rejection, IL2c unexpectedly lowered the tumor microenvironmental CD8+/Treg ratio. IL2c reduced tumor microenvironmental Treg suppression and induced a fragile Treg phenotype, helping explain improved efficacy despite numerically increased Tregs without affecting Treg in draining lymph nodes. IL2c also reduced Treg-mediated, high-affinity IL2R signaling needed for optimal Treg functions, a likely mechanism for reduced Treg suppression. Effector T-cell IL2R signaling was simultaneously improved, suggesting that IL2c inhibits Treg functions without hindering effector T cells, a limitation of most Treg depletion agents. Anti-PD-L1 antibody did not treat ID8agg, but adding IL2c generated complete tumor regressions and protective immune memory not achieved by either monotherapy. Similar anti-PD-L1 augmentation of IL2c and degradation of Treg functions were seen in subcutaneous B16 melanoma. Thus, IL2c is a multifunctional immunotherapy agent that stimulates immunity, reduces immunosuppression in a site-specific manner, and combines with other immunotherapies to treat distinct tumors in distinct anatomic compartments. SIGNIFICANCE: These findings present CD122-targeted IL2 complexes as an advancement in cancer immunotherapy, as they reduce Treg immunosuppression, improve anticancer immunity, and boost PD-L1 immune checkpoint blockade efficacy in distinct tumors and anatomic locations.

IL-15 superagonist N-803 improves IFNγ production and killing of leukemia and ovarian cancer cells by CD34+ progenitor-derived NK cells

Allogeneic natural killer (NK) cell transfer is a potential immunotherapy to eliminate and control cancer. A promising source are CD34 + hematopoietic progenitor cells (HPCs), since large numbers of cytotoxic NK cells can be generated. Effective boosting of NK cell function can be achieved by interleukin (IL)-15. However, its in vivo half-life is short and potent trans-presentation by IL-15 receptor α (IL-15Rα) is absent. Therefore, ImmunityBio developed IL-15 superagonist N-803, which combines IL-15 with an activating mutation, an IL-15Rα sushi domain for trans-presentation, and IgG1-Fc for increased half-life. Here, we investigated whether and how N-803 improves HPC-NK cell functionality in leukemia and ovarian cancer (OC) models in vitro and in vivo in OC-bearing immunodeficient mice. We used flow cytometry-based assays, enzyme-linked immunosorbent assay, microscopy-based serial killing assays, and bioluminescence imaging, for in vitro and in vivo experiments. N-803 increased HPC-NK cell proliferation and interferon (IFN)γ production. On leukemia cells, co-culture with HPC-NK cells and N-803 increased ICAM-1 expression. Furthermore, N-803 improved HPC-NK cell-mediated (serial) leukemia killing. Treating OC spheroids with HPC-NK cells and N-803 increased IFNγ-induced CXCL10 secretion, and target killing after prolonged exposure. In immunodeficient mice bearing human OC, N-803 supported HPC-NK cell persistence in combination with total human immunoglobulins to prevent Fc-mediated HPC-NK cell depletion. Moreover, this combination treatment decreased tumor growth. In conclusion,  N-803 is a promising IL-15-based compound that boosts HPC-NK cell expansion and functionality in vitro and in vivo. Adding N-803 to HPC-NK cell therapy could improve cancer immunotherapy.

Humanized Mouse as a Tool to Predict Immunotoxicity of Human Biologics

Advancements in science enable researchers to constantly innovate and create novel biologics. However, the use of non-human animal models during the development of biologics impedes identification of precise in vivo interactions between the human immune system and treatments. Due to lack of this understanding, adverse effects are frequently observed in healthy volunteers and patients exposed to potential biologics during clinical trials. In this study, we evaluated and compared the effects of known immunotoxic biologics, Proleukin^®/IL-2 and OKT3 in humanized mice (reconstituted with human fetal cells) to published clinical outcomes. We demonstrated that humanized mice were able to recapitulate in vivo pathological changes and human-specific immune responses, such as elevated cytokine levels and modulated lymphocytes and myeloid subsets. Given the high similarities of immunological side effects observed between humanized mice and clinical studies, this model could be used to assess immunotoxicity of biologics at a pre-clinical stage, without placing research participants and/or patients at risk.

The hypoxic tumour microenvironment: A safe haven for immunosuppressive cells and a therapeutic barrier to overcome

Dating back to the seminal work of Paul Ehrlich, the idea of harnessing our immune system to eliminate cancerous cells is now over a century old. In the presence of a functional immune system that so efficiently guards the host against developing neoplasms, tumour cells must evolve sophisticated strategies to escape immune destruction in order to give rise to clinically detectable cancers. A new way of treating cancer would thus be to target the immune system itself rather than the tumour, and extensive studies in randomised trials have cemented the possibility of using immunotherapy for treating advanced-stage cancers. Immunotherapy, however, is only tolerated in a minority of patients and in many cases, patients suffer from adverse immune-related reactions when the immune system goes into overdrive. A primary barrier thwarting the development of effective immunotherapy seems to coalesce into the peculiarities of the tumour microenvironment for which hypoxia is a key feature. Here, we review emerging themes on how hypoxia contributes to immune suppression and obstructs anti-tumour effector cell functions. We discuss the challenges and opportunities relating to the potential for dually targeting hypoxia and the immune system to promote durable and favourable responses in cancer patients.

Engineered IL-21 Cytokine Muteins Fused to Anti-PD-1 Antibodies Can Improve CD8+ T Cell Function and Anti-tumor Immunity

Inhibitors that block the programmed cell death-1 (PD-1) pathway can potentiate endogenous antitumor immunity and have markedly improved cancer survival rates across a broad range of indications. However, these treatments work for only a minority of patients. The efficacy of anti-PD-1 inhibitors may be extended by cytokines, however, the incorporation of cytokines into therapeutic regimens has significant challenges. In their natural form when administered as recombinant proteins, cytokine treatments are often associated with low response rates. Most cytokines have a short half-life which limits their exposure and efficacy. In addition, cytokines can activate counterregulatory pathways, in the case of immune-potentiating cytokines this can lead to immune suppression and thereby diminish their potential efficacy. Improving the drug-like properties of natural cytokines using protein engineering can yield synthetic cytokines with improved bioavailability and tissue targeting, allowing for enhanced efficacy and reduced off-target effects. Using structure guided engineering we have designed a novel class of antibody-cytokine fusion proteins consisting of a PD-1 targeting antibody fused together with an interleukin-21 (IL-21) cytokine mutein. Our bifunctional fusion proteins can block PD-1/programmed death-ligand 1 (PD-L1) interaction whilst simultaneously delivering IL-21 cytokine to PD-1 expressing T cells. Targeted delivery of IL-21 can improve T cell function in a manner that is superior to anti-PD-1 monotherapy. Fusion of engineered IL-21 variants to anti-PD1 antibodies can improve the drug-like properties of IL-21 cytokine leading to improved cytokine serum half-life allowing for less frequent dosing. In addition, we show that targeted delivery of IL-21 can minimize any potential detrimental effect on local antigen-presenting cells. A highly attenuated IL-21 mutein variant (R9E:R76A) fused to a PD-1 antibody provides protection in a humanized mouse model of cancer that is refractory to anti-PD-1 monotherapy. Collectively, our preclinical data demonstrate that this approach may improve upon and extend the utility of anti-PD-1 therapeutics currently in the clinic.

Targeting tumors with IL-21 reshapes the tumor microenvironment by proliferating PD-1intTim-3-CD8+ T cells

The lack of sufficient functional tumor-infiltrating lymphocytes in the tumor microenvironment (TME) is one of the primary indications for the poor prognosis of patients with cancer. In this study, we developed an Erbitux-based IL-21 tumor-targeting fusion protein (Erb-IL21) to prolong the half-life and improve the antitumor efficacy of IL-21. Compared with Erb-IL2, Erb-IL21 demonstrated much lower toxicity in vivo. Mechanistically, Erb-IL21 selectively expanded functional cytotoxic T lymphocytes but not dysfunctional CD8+ T cells in the TME. We observed that the IL-21-mediated antitumor effect largely depended on the existing intratumoral CD8+ T cells, instead of newly migrated CD8+ T cells. Furthermore, Erb-IL21 overcame checkpoint blockade resistance in mice with advanced tumors. Our study reveals that Erb-IL21 can target IL-21 to tumors and maximize the antitumor potential of checkpoint blockade by expending a subset of tumor antigen-specific CD8+ T cells to achieve effective tumor control.

Bempegaldesleukin selectively depletes intratumoral Tregs and potentiates T cell-mediated cancer therapy

High dose interleukin-2 (IL-2) is active against metastatic melanoma and renal cell carcinoma, but treatment-associated toxicity and expansion of suppressive regulatory T cells (Tregs) limit its use in patients with cancer. Bempegaldesleukin (NKTR-214) is an engineered IL-2 cytokine prodrug that provides sustained activation of the IL-2 pathway with a bias to the IL-2 receptor CD122 (IL-2Rβ). Here we assess the therapeutic impact and mechanism of action of NKTR-214 in combination with anti-PD-1 and anti-CTLA-4 checkpoint blockade therapy or peptide-based vaccination in mice. NKTR-214 shows superior anti-tumor activity over native IL-2 and systemically expands anti-tumor CD8+ T cells while inducing Treg depletion in tumor tissue but not in the periphery. Similar trends of intratumoral Treg dynamics are observed in a small cohort of patients treated with NKTR-214. Mechanistically, intratumoral Treg depletion is mediated by CD8+ Teff-associated cytokines IFN-γ and TNF-α. These findings demonstrate that NKTR-214 synergizes with T cell-mediated anti-cancer therapies.

Hepatic Stellate Cells in Liver Tumor

Hepatocellular carcinoma and intrahepatic cholangiocarcinoma are the most common types of primary liver cancers. Moreover, the liver is the second most frequently involved organ in cancer metastasis after lymph nodes. The tumor microenvironment is crucial for the development of both primary and secondary liver cancers. The hepatic microenvironment consists of multiple cell types, including liver sinusoidal endothelial cells, Kupffer cells, natural killer cells, liver-associated lymphocytes, and hepatic stellate cells (HSCs). The microenvironment of a normal liver changes to a tumor microenvironment when tumor cells exist or tumor cells migrate to and multiply in the liver. Interactions between tumor cells and non-transformed cells generate a tumor microenvironment that contributes significantly to tumor progression. HSCs play a central role in the tumor microenvironment crosstalk. As this crosstalk is crucial for liver carcinogenesis and liver-tumor development, elucidating the mechanism underlying the interaction of HSCs with the tumor microenvironment could provide potential therapeutic targets for liver cancer.

CXCL12/CXCR4 signal transduction in diseases and its molecular approaches in targeted-therapy

Chemokines are small molecules called "chemotactic cytokines" and regulate many processes like leukocyte trafficking, homing of immune cells, maturation, cytoskeletal rearrangement, physiology, migration during development, and host immune responses. These proteins bind to their corresponding 7-membrane G-protein-coupled receptors. Chemokines and their receptors are anti-inflammatory factors in autoimmune conditions, so consider as potential targets for neutralization in such diseases. They also express by cancer cells and function as angiogenic factors, and/or survival/growth factors that enhance tumor angiogenesis and development. Among chemokines, the CXCL12/CXCR4 axis has significantly been studied in numerous cancers and autoimmune diseases. CXCL12 is a homeostatic chemokine, which is acts as an anti-inflammatory chemokine during autoimmune inflammatory responses. In cancer cells, CXCL12 acts as an angiogenic, proliferative agent and regulates tumor cell apoptosis as well. CXCR4 has a role in leukocyte chemotaxis in inflammatory situations in numerous autoimmune diseases, as well as the high levels of CXCR4, observed in different types of human cancers. These findings suggest CXCL12/CXCR4 as a potential therapeutic target for therapy of autoimmune diseases and open a new approach to targeted-therapy of cancers by neutralizing CXCL12 and CXCR4. In this paper, we reviewed the current understanding of the role of the CXCL12/CXCR4 axis in disease pathology and cancer biology, and discuss its therapeutic implications in cancer and diseases.

Regulatory T cells in cancer immunosuppression - implications for anticancer therapy

Regulatory T (T_reg) cells, an immunosuppressive subset of CD4⁺ T cells characterized by the expression of the master transcription factor forkhead box protein P3 (FOXP3), are a component of the immune system with essential roles in maintaining self-tolerance. In addition, T_reg cells can suppress anticancer immunity, thereby hindering protective immunosurveillance of neoplasia and hampering effective antitumour immune responses in tumour-bearing hosts, thus promoting tumour development and progression. Identification of the factors that are specifically expressed in T_reg cells and/or that influence T_reg cell homeostasis and function is important to understanding cancer pathogenesis and to identifying therapeutic targets. Immune-checkpoint inhibitors (ICIs) have provided a paradigm shift in the treatment of cancer. Most immune-checkpoint molecules are expressed in T_reg cells, but the effects of ICIs on T_reg cells, and thus the contributions of these cells to treatment responses, remain unclear. Notably, evidence indicates that ICIs targeting programmed cell death 1 (PD-1) might enhance the immunosuppressive function of T_reg cells, whereas cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors might deplete these cells. Thus, although manipulation of T_reg cells is a promising anticancer therapeutic strategy, approaches to controlling these cells require further research. Herein, we discuss novel insights into the roles of T_reg cells in cancer, which can hopefully be used to develop T_reg cell-targeted therapies and facilitate immune precision medicine.

Cyclophosphamide, Fluorouracil and subcutaneous Interleukin-2 in the treatment of advanced GIST: A Case Report

A male 68 years hold patient was admitted to surgical ward for hemorrhagic shock. After CT scan detection of 6x5 cm neoformation of first jejunal loop, he was submitted to segmental resection and pathological diagnosis was gastrointestinal stromal tumor. The patient was defined as high-risk according to Takahashi criteria, but refused Imatinib adjuvant therapy. After 15 months of disease-free interval, he developed bilobar liver metastases. After treatment with Imatinib 400 mg he reported G3 hepatotoxicity resolved with temporary suspension, he continue low dose with stable disease. After liver progression, he resumed Imatinib full dose with disease stabilization for 9 months. After liver progression, second line Sunitinib 37,5 mg/day was started for four months with stable disease. After further liver and lymph node mediastinal progression he was treated for four months with Regorafenib with disease stabilization. Patient developed slow but inexorable progression of liver disease with severe abdominal pain resistant to opioid and was treated with authorized compassionate program comprising Cyclophosphamide 300 mg/sqm and Fluorouracil 500 mg/sqm on day 1 intravenously followed by Interleukin-2 4.5 MUI subcutaneously on days 3–6 and 17–20 every four weeks. After three cycles the patients obtained a relevant subjective improvement with partial response on mediastinal lymph node and liver stabilization. A substantial increase on neutrophil, lymphocytes, monocytes, platelets, T regulator cells count, and a decrease on platelets/lymphocytes, CD8/T regulator cells ratio, CD8, NK count and C-reactive protein value were observed after treatment compared to basal value. The toxicity was mild represented by fever G1, flue-like-syndrome G1 during the treatment. After four cycle of chemo-immunotherapy, the patient demonstrated progression of disease and died five months after treatment. Noteworthy is the temporal disease control with significant symptomatic improvement achieved for the first time with this chemo-immunotherapeutic combination in a patient with very advanced pretreated GIST.

The Contribution of the Immune System in Bone Metastasis Pathogenesis

Bone metastasis is associated with significant morbidity for cancer patients and results in a reduced quality of life. The bone marrow is a fertile soil containing a complex composition of immune cells that may actually provide an immune-privileged niche for disseminated tumor cells to colonize and proliferate. In this unique immune milieu, multiple immune cells including T cells, natural killer cells, macrophages, dendritic cells, myeloid-derived suppressor cells, and neutrophils are involved in the process of bone metastasis. In this review, we will discuss the crosstalk between immune cells in bone microenvironment and their involvement with cancer cell metastasis to the bone. Furthermore, we will highlight the anti-tumoral and pro-tumoral function of each immune cell type that contributes to bone metastasis. We will end with a discussion of current therapeutic strategies aimed at sensitizing immune cells.

Effects of tumor metabolic microenvironment on regulatory T cells

Recent studies have shown that on one hand, tumors need to obtain a sufficient energy supply, and on the other hand they must evade the body’s immune surveillance. Because of their metabolic reprogramming characteristics, tumors can modify the physicochemical properties of the microenvironment, which in turn affects the biological characteristics of the cells infiltrating them. Regulatory T cells (Tregs) are a subset of T cells that regulate immune responses in the body. They exist in large quantities in the tumor microenvironment and exert immunosuppressive effects. The main effect of tumor microenvironment on Tregs is to promote their differentiation, proliferation, secretion of immunosuppressive factors, and chemotactic recruitment to play a role in immunosuppression in tumor tissues. This review focuses on cell metabolism reprogramming and the most significant features of the tumor microenvironment relative to the functional effects on Tregs, highlighting our understanding of the mechanisms of tumor immune evasion and providing new directions for tumor immunotherapy.

Cyclophosphamide with or without fluorouracil followed by subcutaneous or intravenous interleukin-2 use in solid tumors: A feasibility off-label experience

BACKGROUND

Immune tolerance seems to correlate with disease progression and T regulatory cells (Tregs) and myeloid-derived suppressor cells play a relevant role in immunosuppression. Cyclophosphamide (Cyt) and Fluorouracil (FU) seem to reduce these cell populations.

METHODS AND OBJECTIVE

Establishing safety, feasibility, activity and impact on the immune system (neutrophil/lymphocyte [N/L], platelet/L [Plt/L], monocyte [M] and lymphocyte subpopulation (CD3, CD4, CD8, CD16, HLADR/CD3, Tregs, cells count), CD8/Treg and C-reactive protein (CRP).

TREATMENT

1) Cyt 300 mg/sqm ± FU 500 mg/sqm day (d) 1 and interleukin 2 (IL-2) 18 MUI/sqm intravenous (I.V.) d 4-6, 18-20 or 2) Cyt 300 mg/sqm + FU 500 mg/sqm day d 1, IL-2 4.5 MUI subcutaneous (S.C.) d 3-6, 17-20. The cycle was repeated every four weeks for 2 cycles. Stable or responding patients (pts) continued therapy for 3 cycles.

RESULTS

From February 2014 to December 2016, 13/14 pre-treated pts (mean 3 lines) with solid tumors were enrolled. Male/Female: 1/1. The median age and Eastern Cooperative Oncology Group Performance Status (ECOG PS) was 68 years and 1 respectively. Mean 2 cycles of therapy were administered. G3-4 toxicities presented as diarrhea and bleeding anemia in 2 pts and proteinuria and erhytroderma in 1pt, respectively. Regarding the hematological profile, a more reduction in Plt, less decrease of Plt/Ly, and less increase of Treg with I.V. than S.C. IL-2 administration was observed. However a transient decrease of Treg on day 7 of first cycle in the I.V. IL-2 was reported.

RESPONSE

PR 3 (23%), SD 3 (23%), PD 7 (54%). The response duration was 2+ and 3 months in 2 HCC and 18+ months in the pancreatic cancer (PC). Pathological CR was reported in one HCC treated with I.V. IL-2. The median progression-free-survival (PFS) and overall survival (OS) were 1 and 7 months.

CONCLUSION

Cyt-FU-IL-2 can be considered safe, feasible and moderately active in heavily pre-treated pts. Plt, Plt/Ly, CD8/Treg and a transient Tregs reduction were observed without significative difference on survival.

The synergy between ionizing radiation and immunotherapy in the treatment of prostate cancer

There has been a surge in the use of immunotherapy for genitourinary malignancies. Immunotherapy is an established treatment for metastatic renal cell carcinoma and nonmuscle invasive bladder cancer, but its potential for treating prostate cancer (PCa) remains under investigation. Despite reported survival benefits, no published Phase III PCa trials using immunotherapy only as a treatment has demonstrated direct antitumor effects by reducing prostate-specific antigen levels. Subsequently, the thought of combining immunotherapy with other treatment modalities has gained traction as a way to achieving optimal results. Based on data from other malignancies, it is hypothesized that radiotherapy and immunotherapy can act synergistically to improve outcomes. We will discuss the clinical potential of combining immune-based treatments with radiotherapy as a treatment for advanced PCa.

miR200-regulated CXCL12β promotes fibroblast heterogeneity and immunosuppression in ovarian cancers

High-grade serous ovarian cancers (HGSOC) have been subdivided into molecular subtypes. The mesenchymal HGSOC subgroup, defined by stromal-related gene signatures, is invariably associated with poor patient survival. We demonstrate that stroma exerts a key function in mesenchymal HGSOC. We highlight stromal heterogeneity in HGSOC by identifying four subsets of carcinoma-associated fibroblasts (CAF-S1-4). Mesenchymal HGSOC show high content in CAF-S1 fibroblasts, which exhibit immunosuppressive functions by increasing attraction, survival, and differentiation of CD25⁺FOXP3⁺ T lymphocytes. The beta isoform of the CXCL12 chemokine (CXCL12β) specifically accumulates in the immunosuppressive CAF-S1 subset through a miR-141/200a dependent-mechanism. Moreover, CXCL12β expression in CAF-S1 cells plays a crucial role in CAF-S1 immunosuppressive activity and is a reliable prognosis factor in HGSOC, in contrast to CXCL12α. Thus, our data highlight the differential regulation of the CXCL12α and CXCL12β isoforms in HGSOC, and reveal a CXCL12β-associated stromal heterogeneity and immunosuppressive environment in mesenchymal HGSOC.

Contribution of Regulatory T Cells in Nucleotide-Binding Oligomerization Domain 2 Response to Influenza Virus Infection

Influenza A virus (IAV) is recognized to cause severe pulmonary illnesses in humans, particularly in elderly and children. One of the features associated with IAV infection is an excessive lung inflammation due to an uncontrolled immune response. The nucleotide-binding oligomerization domain 2 (NOD2) receptor is known to recognize ssRNA viruses such as IAV, but its role in the inflammatory process during viral infections remains to be clarified. In a previous report, we have shown that activation of NOD2 with muramyl dipeptide (MDP) significantly reduces both viral loads and lung inflammation and also improves pulmonary function during IAV infection. These findings prompted us to further investigate whether NOD2 receptor may contribute to regulate inflammation during viral infection. In the present study, we show that administration of MDP to mice infected with IAV stimulates the migration of regulatory T (Treg) cells to the lungs. Such a presence of Treg cells was also accompanied with a reduction of neutrophils in the lungs during IAV infection, which correlated, with a significant decrease of Th17 cells. In our model, Treg cell recruitment is dependent of CXCL12 and CCL5 chemokines. Moreover, we show that the presence of Ly6C^low patrolling monocytes is required for Treg cells mobilization to the lung of mice treated with MDP. In fact, following monocyte depletion by administration of clodronate liposome, mobilization of Treg cells to the lungs of treated mice was found to occur when circulating Ly6C^low monocytes begin to reemerge. In addition, we also detected an increased production of TGF-β, a cytokine contributing to Treg activity when blood Ly6C^low monocytes are restored. Together, our results demonstrate that MDP treatment can promote an anti-inflammatory environment through the mobilization of Treg cells to the lung, a mechanism that requires the presence of Ly6C^low monocytes during IAV infection. Overall, our results suggest that activation of NOD2 receptor could be an appealing approach to control pulmonary inflammation in patients infected with IAV.

T-Cell Therapy Enabling Adenoviruses Coding for IL2 and TNFα Induce Systemic Immunomodulation in Mice With Spontaneous Melanoma

The immunosuppressive microenvironment of solid tumors renders adoptively transferred T cells hypofunctional. However, adenoviral delivery of immunostimulatory cytokines IL2 and TNFα can significantly improve the efficacy of adoptive T-cell therapy. Using ret transgenic mice that spontaneously develop skin malignant melanoma, we analyzed the mechanism of action of adenoviruses coding for IL2 and TNFα in combination with adoptive transfer of TCR-transgenic TRP-2-specific T cells. Following T-cell therapy and intratumoral virus injection, a significant increase in antigen-experienced, tumor-reactive PD-1 CD8 T cells was seen in both cutaneous lesions and in metastatic lymph nodes. A reverse correlation between tumor weight and the number of tumor-reactive PD-1 tumor-infiltrating lymphocytes (TILs) was observed, suggesting that these T cells could target and kill tumor cells. It is interesting to note that, local expression of cytokines did not affect intratumoral levels of T-regulatory cells (Tregs), which had previously been associated with systemic IL2 therapy. Instead, Ad5-IL2 induced upregulation of IL2 receptor α-chain (CD25) on conventional CD4CD25Foxp3 cells, indicating that these CD4 T cells may contribute to CD8 T-cell activation and/or homing. Signs of therapy-induced resistance were also observed as the expression of PD-L1 on tumor-infiltrating granulocytic myeloid-derived suppressor cells was upregulated as a reaction to PD-1+ TILs. Finally, beneficial ratios between tumor-reactive PD-1 CD8 TILs and immunosuppressive cell subsets (Tregs and nitric oxide-producing myeloid-derived suppressor cells) were observed in primary and secondary tumor sites, indicating that local delivery of IL2 and TNFα coding adenoviruses can systemically modify the cellular composition of the tumor microenvironment in favor of adoptively transferred T cells.

Prolonged survival after intraperitoneal interleukin-2 immunotherapy for recurrent ovarian cancer

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A case report of a 14 year remission of recurrent ovarian cancer with intraperitoneal aldesleukin (IL-2) is presented.

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Intraperitoneal IL-2 was given with little toxicity.

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Immunotherapy may have the potential for durable remissions in ovarian cancer.

CXCL13-producing TFH cells link immune suppression and adaptive memory in human breast cancer

T follicular helper cells (TFH cells) are important regulators of antigen-specific B cell responses. The B cell chemoattractant CXCL13 has recently been linked with TFH cell infiltration and improved survival in human cancer. Although human TFH cells can produce CXCL13, their immune functions are currently unknown. This study presents data from human breast cancer, advocating a role for tumor-infiltrating CXCL13-producing (CXCR5-) TFH cells, here named TFHX13 cells, in promoting local memory B cell differentiation. TFHX13 cells potentially trigger tertiary lymphoid structure formation and thereby generate germinal center B cell responses at the tumor site. Follicular DCs are not potent CXCL13 producers in breast tumor tissues. We used the TFH cell markers PD-1 and ICOS to identify distinct effector and regulatory CD4+ T cell subpopulations in breast tumors. TFHX13 cells are an important component of the PD-1hiICOSint effector subpopulation and coexpanded with PD-1intICOShiFOXP3hi Tregs. IL2 deprivation induces CXCL13 expression in vitro with a synergistic effect from TGFβ1, providing insight into TFHX13 cell differentiation in response to Treg accumulation, similar to conventional TFH cell responses. Our data suggest that human TFHX13 cell differentiation may be a key factor in converting Treg-mediated immune suppression to de novo activation of adaptive antitumor humoral responses in the chronic inflammatory breast cancer microenvironment.

Regulatory T Cells: Molecular and Cellular Basis for Immunoregulation

CD4⁺ regulatory T cells (Tregs) are a highly immune-suppressive subset of CD4⁺ T cells, characterized by expression of the master regulatory transcription factor FOXP3. Tregs are proven to play central roles in the maintenance of self-tolerance in healthy individuals. Tregs are involved in maintaining immune homeostasis: they protect hosts from developing autoimmune diseases and allergy, whereas in malignancies, they promote tumor progression by suppressing anti-tumor immunity. Elucidating factors influencing Treg homeostasis and function have important implications for understanding disease pathogenesis and identifying therapeutic opportunities. Thus, the manipulating Tregs for up- or down-regulation of their suppressive function is a new therapeutic strategy for treating various diseases including autoimmune disorders and cancer. This review will focus on recent advances in how Tregs integrate extracellular and intracellular signals to control their survival and stability. Deeper mechanistic understanding of disease-specific Treg development, maintenance, and function could make disease-specific Treg-targeted therapy more effective, resulting in an increase of efficacy and decrease of side effects related to manipulating Tregs.

Effect of Th1/Th2 cytokine administration on proinflammatory SKOV-3 cell activation

INTRODUCTION

Interleukin(IL)-1β, IL-6 and IL-12 might associate with inflammatory processes in a tumor progression and create a specific microenvironment for tumor growth. The aim of the study was to assess whether the Th1 and Th2 type cytokines, such as IL-2 and IL-10, affect ovarian carcinoma continuous cell line (SKOV-3) pro-inflammatory activation.

MATERIAL AND METHODS

SKOV-3 ovarian cells and peripheral blood mononuclear cells (PBMCs) were stimulated by IL-2 and IL-10. Additionally, SKOV-3 ovarian cells and PBMCs were co-cultured together. Proinflammatory activation of cancer cells was evaluated by measurement of IL-1β and IL-6 levels in culture fluid after 72 h of incubation.

RESULTS

SKOV-3 cells and PBMCs secreted IL-1β and IL-6. After stimulation by IL-2 and IL-10, secretion of studied parameters was changed in a dose-dependent manner. The addition of a higher IL-2 level gave rise to an increase of IL-1β, IL-6 and IL-12 secretion in SKOV-3 cells. Stimulation by IL-10 increased only IL-1β secretion in SKOV-3 cells. However, IL-6 secretion decreased after stimulation with 25 ng/ml IL-10. Activatory effects of IL-2 and inhibitory effects of IL-10 in co-culture of SKOV-3 and PBMCs were observed.

CONCLUSIONS

Our results suggested that Th1/Th2 type of cytokines might influence pro-inflammatory activation of SKOV-3 ovarian cells. Co-cultures of SKOV-3 and PBMCs showed significant changes in cross-talk between cancer and immune cells.

Inflammatory regulatory T cells in the microenvironments of ulcerative colitis and colon carcinoma

Foxp3(+)CD4(+) regulatory T (Treg) cells are thought to express negligible levels of effector cytokines, and inhibit immune responses and inflammation. Here, we have identified a population of IL-8(+)Foxp3(+)CD4(+) T cells in human peripheral blood, which is selectively increased in the microenvironments of ulcerative colitis and colon carcinoma. Phenotypically, this population is minimally overlapping with IL-17(+)Foxp3(+)CD4(+) T cells, and is different from IL-8(-)Foxp3(+)CD4(+) T cells in the same microenvironment. 40-60% of IL-8(+)Foxp3(+)CD4(+) T cells exhibit naive phenotype and express CD127, whereas IL-8(-)Foxp3(+)CD4(+) cells are basically memory T cells and express minimal CD127. The levels of CXCR5 expression are higher in IL-8(+)Foxp3(+) cells than in IL-8(-)Foxp3(+) cells. IL-2 and TGFβ induce IL-8(+)Foxp3(+) T cells. Exogenous Foxp3 expression promotes IL-8(+)Foxp3(+) T cells and inhibits effector cytokine IFNγ and IL-2 expression. Furthermore, Foxp3 binds to IL-8 proximal promoter and increases its activity. Functionally, IL-8(+)Foxp3(+) T cells inhibit T cell proliferation and effector cytokine production, but stimulate inflammatory cytokine production in the colon tissues, and promote neutrophil trafficking through IL-8. Thus, IL-8(+)Foxp3(+) cells may be an "inflammatory" Treg subset, and possess inflammatory and immunosuppressive dual biological activities. Given their dual roles and localization, these cells may be in a unique position to support tumor initiation and development in human chronic inflammatory environment.

[Immunological aspects of ovarian cancer: Therapeutic perspectives]

Ovarian cancer is recognized by the immunological system of its host. Initially, it is effective to destroy and eliminate the cancer. But gradually, resistant tumor cells more aggressive and those able to protect themselves by inducing immune tolerance will be selected. Immunotherapy to be effective should consider both components of immune response with an action on cytotoxic immune effectors and action on tolerance mechanisms. The manipulations of the immune system should be cautious, because the immune effects are not isolated. A theoretically efficient handling may simultaneously cause an adverse effect which was not envisaged and could neutralize the benefits of treatment. Knowledge of tolerance mechanisms set up by the tumor is for the clinician a prerequisite before they prescribe these treatments. For each cancer, the knowledge of its immunological status is a prerequisite to propose adapted immunological therapies.

Roles of regulatory T cells in cancer immunity

CD4(+) regulatory T cells (Tregs) expressing the transcription factor FoxP3 are highly immune suppressive and play central roles in the maintenance of self-tolerance and immune homeostasis, yet in malignant tumors they promote tumor progression by suppressing effective antitumor immunity. Indeed, higher infiltration by Tregs is observed in tumor tissues, and their depletion augments antitumor immune responses in animal models. Additionally, increased numbers of Tregs and, in particular, decreased ratios of CD8(+) T cells to Tregs among tumor-infiltrating lymphocytes are correlated with poor prognosis in various types of human cancers. The recent success of cancer immunotherapy represented by immune checkpoint blockade has provided a new insight in cancer treatment, yet more than half of the treated patients did not experience clinical benefits. Identifying biomarkers that predict clinical responses and developing novel immunotherapies are therefore urgently required. Cancer patients whose tumors contain a large number of neoantigens stemming from gene mutations, which have not been previously recognized by the immune system, provoke strong antitumor T-cell responses associated with clinical responses following immune checkpoint blockade, depending on the resistance to Treg-mediated suppression. Thus, integration of a strategy restricting Treg-mediated immune suppression may expand the therapeutic spectrum of cancer immunotherapy towards patients with a lower number of neoantigens. In this review, we address the current understanding of Treg-mediated immune suppressive mechanisms in cancer, the involvement of Tregs in cancer immunotherapy, and strategies for effective and tolerable Treg-targeted therapy.

Durable complete responses off all treatment in patients with metastatic malignant melanoma after sequential immunotherapy followed by a finite course of BRAF inhibitor therapy

We report 3 cases of durable complete response (CR) in patients with BRAF-mutated metastatic melanoma who were initially treated unsuccessfully with sequential immunotherapies (high dose interleukin 2 followed by ipilimumab with or without concurrent radiation therapy). After progression during or post immunotherapy, these patients were given BRAF inhibitor therapy and developed rapid CRs. Based on the concomitant presence of autoimmune manifestations (including vitiligo and hypophysitis), we postulated that there was a synergistic effect between the prior immune therapy and the BRAF targeting agents. Accordingly, the inhibitors were gradually weaned off beginning at 3 months and were stopped completely at 9-12 months. The three patients remain well and in CR off of all therapy at up to 15 months radiographic follow-up. The institution of the BRAF therapy was associated with development of severe rheumatoid-like arthritis in 2 patients which persisted for months after discontinuation of therapy, suggesting it was not merely a known toxicity of BRAF inhibitors (arthralgias). On immunologic analysis, these patients had high levels of non-T-regulatory, CD4 positive effector phenotype T-cells, which persisted after completion of therapy. Of note, we had previously reported a similar phenomenon in patients with metastatic melanoma who failed high dose interleukin-2 and were then placed on a finite course of temozolomide with rapid complete responses that have remained durable for many years after discontinuation of temozolomide. We postulate that a finite course of cytotoxic or targeted therapy specific for melanoma given after apparent failure of prior immunotherapy can result in complete and durable remissions that may persist long after the specific cytotoxic or targeted agents have been discontinued suggesting the existence of sequence specific synergism between immunotherapy and these agents. Here, we discuss these cases in the context of the literature on synergy between conventional or targeted cytotoxic therapy and immunotherapy in cancer treatment.

Immunotherapy for ovarian cancer

OPINION STATEMENT

All work referenced herein relates to treatment of epithelial ovarian carcinomas, as their treatment differs from ovarian germ cell cancers and other rare ovarian cancers, the treatments of which are addressed elsewhere. Fallopian tube cancers and primary peritoneal adenocarcinomatosis are also generally treated as epithelial ovarian cancers. The standard of care initial treatment of advanced stage epithelial ovarian cancer is optimal debulking surgery as feasible plus chemotherapy with a platinum plus a taxane agent. If this front-line approach fails, as it too often the case, several FDA-approved agents are available for salvage therapy. However, because no second-line therapy for advanced-stage epithelial ovarian cancer is typically curative, we prefer referral to clinical trials as logistically feasible, even if it means referring patients outside our system. Immune therapy has a sound theoretical basis for treating carcinomas generally, and for treating ovarian cancer in particular. Advances in understanding the immunopathogenic basis of ovarian cancer, and the immunopathologic basis for prior failures of immunotherapy for it and other carcinomas promises to afford novel treatment approaches with potential for significant efficacy, and reduced toxicities compared with cytotoxic agents. Thus, referral to early phase immunotherapy trials for ovarian cancer patients that fail conventional treatment merits consideration.

Effect of targeted ovarian cancer therapy using amniotic fluid mesenchymal stem cells transfected with enhanced green fluorescent protein-human interleukin-2 in vivo

The aim of the present study was to investigate the effect of using amniotic fluid mesenchymal stem cells (AF-MSCs) in targeted ovarian cancer therapy in vivo. AF-MSCs were isolated from human second trimester AF and a plasmid, enhanced green fluorescent protein-human interleukin-2 (pEGFP-hIL-2) was formed. The plasmid was stably transfected into the AF-MSCs and the cells were intravenously injected into ovarian cancer nude mice models. Following stable transfection of the vector, tumor formation, and the expression and activity of hIL-2 were investigated, and microscopic pathological examinations of the tumor were performed. It was found that AF-MSCs exhibited high motility during migration in vivo, and the vector, pEGFP-hIL-2 can be stably transfected into AF-MSCs. Following stable transfection, this type of stem cell is able to successfully transport the therapeutic gene, IL-2, migrate to the ovarian cancer tumor site to secrete the functional IL-2 and treat the tumor. Thus, AF-MSCs may serve as transporters for therapeutic genes targeting ovarian tumor sites and, therefore, be involved in the treatment of tumors.