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For many solid tumors, immune checkpoint blockade therapy has become first line treatment, yet a large proportion of patients with immunologically cold tumors do not benefit due to the paucity of tumor infiltrating lymphocytes. Here we show that the orphan G Protein-Coupled Receptor 182 (GPR182) contributes to immunotherapy resistance in cancer via scavenging chemokines that are important for lymphocyte recruitment to tumors. GPR182 is primarily upregulated in melanoma-associated lymphatic endothelial cells (LECs) during tumorigenesis, and this atypical chemokine receptor endocytoses chemokines promiscuously. In GPR182-deficient mice, T cell infiltration into transplanted melanomas increases, leading to enhanced effector T cell function and improved antitumor immunity. Ablation of GPR182 leads to increased intratumoral concentrations of multiple chemokines and thereby sensitizes poorly immunogenic tumors to immune checkpoint blockade and adoptive cellular therapies. CXCR3 blockade reverses the improved antitumor immunity and T cell infiltration characteristic of GPR182-deficient mice. Our study thus identifies GPR182 as an upstream regulator of the CXCL9/CXCL10/CXCR3 axis that limits antitumor immunity and as a potential therapeutic target in immunologically cold tumors., (© 2022. The Author(s).)

Microbe-based cancer immunotherapy has recently emerged as a hot topic for cancer treatment. However, serious limitations remain including infection associated side-effect and unsatisfactory outcomes in clinic trials. Here, we fabricate different sizes of nano-formulations derived from yeast cell wall (YCW NPs) by differential centrifugation. The induction of anticancer immunity of our formulations appears to inversely correlate with their size due to the ability to accumulate in tumor-draining lymph node (TDLN). Moreover, we use a percolation model to explain their distribution behavior toward TDLN. The abundance and functional orientation of each effector component are significantly improved not only in the microenvironment in tumor but also in the TDLN following small size YCW NPs treatment. In combination with programmed death-ligand 1 (PD-L1) blockade, we demonstrate anticancer efficiency in melanoma-challenged mice. We delineate potential strategy to target immunosuppressive microenvironment by microbe-based nanoparticles and highlight the role of size effect in microbe-based immune therapeutics., (© 2022. The Author(s).)

Direct injection of therapies into tumors has emerged as an administration route capable of achieving high local drug exposure and strong anti-tumor response. A diverse array of immune agonists ranging in size and target are under development as local immunotherapies. However, due to the relatively recent adoption of intratumoral administration, the pharmacokinetics of locally-injected biologics remains poorly defined, limiting rational design of tumor-localized immunotherapies. Here we define a pharmacokinetic framework for biologics injected intratumorally that can predict tumor exposure and effectiveness. We find empirically and computationally that extending the tumor exposure of locally-injected interleukin-2 by increasing molecular size and/or improving matrix-targeting affinity improves therapeutic efficacy in mice. By tracking the distribution of intratumorally-injected proteins using positron emission tomography, we observe size-dependent enhancement in tumor exposure occurs by slowing the rate of diffusive escape from the tumor and by increasing partitioning to an apparent viscous region of the tumor. In elucidating how molecular weight and matrix binding interplay to determine tumor exposure, our model can aid in the design of intratumoral therapies to exert maximal therapeutic effect., (© 2022. The Author(s).)

Background: Surgical resection remains an important component of multimodality treatment for most solid tumors. Neoadjuvant immunotherapy has several potential advantages, including in-situ tumor vaccination and pathologic assessment of response in the surgical specimen. We previously described an in-situ tumor vaccination strategy in melanoma using local radiation (RT) and an intratumoral injection of tumor-specific anti-GD2 immunocytokine (IT-IC). Here we tested whether neoadjuvant in-situ tumor vaccination using anti-GD2 immunocytokine and surgical resection, without RT, could generate immunologic memory capable of preventing recurrence or distant metastasis., Methods: Mice bearing GD2 expressing B78 melanoma tumors were treated with neoadjuvant radiation, IT-IC, or combined RT + IT-IC. Surgical resection was performed following neoadjuvant immunotherapy. Immune infiltrate was assessed in the resection specimens. Mice were rechallenged with either B78 contralateral flank tumors or pulmonary seeding of non-GD2 expressing B16 melanoma metastasis induced experimentally. Rejection of rechallenge in mice treated with the various treatment regimens was considered evidence of immunologic memory., Results: Neoadjuvant IT-IC and surgical resection resulted in increased CD8 T cell infiltration, a higher CD8:regulatory T cell ratio, and immunologic memory against contralateral flank rechallenge. The timing of resection did not significantly impact the development of memory, which was present as early as the day of surgery. There was less local wound toxicity with neoadjuvant IT-IC compared with neoadjuvant RT +IT IC. Neoadjuvant IT-IC and resection resulted in the rejection of B16 lung metastasis in a CD4 T cell dependent manner., Conclusions: Neoadjuvant IT-IC generates immunologic memory capable of preventing distant metastasis despite limited efficacy against large primary melanoma tumors. By combining neoadjuvant tumor vaccination and surgery, the toxicity of local RT was avoided. These preclinical data support further investigation regarding the use of neoadjuvant IT-IC in patients with melanoma at high risk for occult distant disease., Competing Interests: Competing interests: VS declares employment in Arrowhead Pharmaceuticals. SDG declares employment and ownership interests in Provenance Biopharmaceuticals., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Prognosis and treatment of metastatic cancer continues to be one of the most difficult and challenging areas of oncology. Treatment usually consists of chemotherapeutics, which may be ineffective due to drug resistance, adverse effects, and dose-limiting toxicity. Therefore, novel approaches such as immunotherapy have been investigated to improve patient outcomes and minimize side effects. S100A9 is a calcium-binding protein implicated in tumor metastasis, progression, and aggressiveness that modulates the tumor microenvironment into an immunosuppressive state. S100A9 is expressed in and secreted by immune cells in the pre-metastatic niche, as well as, post-tumor development, therefore making it a suitable targeted for prophylaxis and therapy. In previous work, it is demonstrated that cowpea mosaic virus (CPMV) acts as an adjuvant when administered intratumorally. Here, it is demonstrated that systemically administered, S100A9-targeted CPMV homes to the lungs leading to recruitment of innate immune cells. This approach is efficacious both prophylactically and therapeutically against lung metastasis from melanoma and breast cancer. The current research will facilitate and accelerate the development of next-generation targeted immunotherapies administered as prophylaxis, that is, after surgery of a primary breast tumor to prevent outgrowth of metastasis, as well as, therapy to treat established metastatic disease., (© 2021 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Adoptive T cell therapy (ACT) requires lymphodepletion preconditioning to eliminate immune-suppressive elements and enable efficient engraftment of adoptively transferred tumor-reactive T cells. As anti-CD4 monoclonal antibody depletes CD4 + immune-suppressive cells, the combination of anti-CD4 treatment and ACT has synergistic potential in cancer therapy. Here, we demonstrate a post-ACT conditioning regimen that involves transient anti-CD4 treatment (CD4 post ). Using murine melanoma, the combined effect of cyclophosphamide preconditioning (CTX pre ), CD4 post , and ex vivo primed tumor-reactive CD8 + T-cell infusion is presented. CTX pre /CD4 post increases tumor suppression and host survival by accelerating the proliferation and differentiation of ex vivo primed CD8 + T cells and endogenous CD8 + T cells. Endogenous CD8 + T cells enhance effector profile and tumor-reactivity, indicating skewing of the TCR repertoire. Notably, enrichment of polyfunctional IL-18Rα hi CD8 + T cell subset is the key event in CTX pre /CD4 post -induced tumor suppression. Mechanistically, the anti-tumor effect of IL-18Rα hi subset is mediated by IL-18 signaling and TCR-MHC I interaction. This study highlights the clinical relevance of CD4 post in ACT and provides insights regarding the immunological nature of anti-CD4 treatment, which enhances anti-tumor response of CD8 + T cells., (© 2021. The Author(s).)

Metastasis is the main cause of death in cancer patients; therefore, new strategies or technologies that can inhibit the growth of primary tumors and their metastatic spread are extremely valuable. In this study, we selected an E-selectin-binding peptide as a targeting ligand and an inhibitor of metastasis, and conjugated this peptide with SN38 and PEG to produce an amphiphilic PEGylated peptide-drug conjugate (PDC). Novel self-assembled nanoparticles were then formed by the amphiphilic conjugate. The particles were actively targeted to the tumor vasculature by the peptide and passively to the tumor site by the enhanced permeability and retention (EPR) effect. As a nano-prodrug, this multifunctional conjugate (PEG-Pep-SN38) could reduce tumor growth, with an effect similar to that of irinotecan. Moreover, it could prolong the survival of mice bearing primary HCT116 tumors, which was not observed for its parent drug, SN38, nor the clinical prodrug of SN38 (irinotecan). Furthermore, this PDC prodrug prevented B16-F10 colonization in the lungs of mice. This study describes a new tumor vasculature-targeting PDC nano-prodrug with convenient preparation and high potential for cancer therapy, with the potential to be applied to other chemotherapeutic drugs., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled, “Tumor Vasculature-Targeting PEGylated Peptide-Drug Conjugate Prodrug Nanoparticles Improve Chemotherapy and Prevent Tumor Metastasis”., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Immunotherapy is revolutionizing cancer treatment. Vaccination of antigenic peptides has been identified as a promising strategy for cancer immunotherapy while insufficient immune responses were stimulated due to low antigenicity. Moreover, immune checkpoint blockade therapy is still limited by a low objective response rate. In this work, cationic polymer-lipid hybrid nanovesicle (P/LNV)-based liposomes are designed to simultaneously deliver tumor vaccines composed of anionic antigen epitopes, toll-like receptor-9 agonist (TLR9), CpG (AE/CpG), and indoleamine-2,3-dioxygenase (IDO) inhibitor, 1-methyl-tryptophan (1-MT), to increase the immunogenicity of peptide antigens and meanwhile block the immune checkpoint. P/LNV liposomes efficiently enhanced the uptake of vaccines by dendritic cells (DCs) and improved the maturation of DCs indicated by the significantly increased percentage of CD86+MHCI+ DCs, resulting in a potent cytotoxic T-lymphocyte (CTL) response against B16-OVA tumor cells in vitro. Importantly, the combination immunotherapy showed significantly higher therapeutic efficiency towards melanoma tumors in mice, compared with an untreated or individual therapy modality. Mechanistically, the co-delivery system could elicit a strong cancer-specific T-cell response, as characterized by the remarkably increased infiltration of CD8+ T cells in the tumor and draining lymph nodes. Altogether, cationic liposomes delivered with tumor vaccines and IDO inhibitor provide a promising platform for cancer immunotherapy by provoking antitumor T-cell immunity and simultaneously reversing the immunosuppressive tumor microenvironment.

The two T cell inhibitory receptors PD-1 and TIM-3 are co-expressed during exhausted T cell differentiation, and recent evidence suggests that their crosstalk regulates T cell exhaustion and immunotherapy efficacy; however, the molecular mechanism is unclear. Here we show that PD-1 contributes to the persistence of PD-1 + TIM-3 + T cells by binding to the TIM-3 ligand galectin-9 (Gal-9) and attenuates Gal-9/TIM-3-induced cell death. Anti-Gal-9 therapy selectively expands intratumoral TIM-3 + cytotoxic CD8 T cells and immunosuppressive regulatory T cells (T reg cells). The combination of anti-Gal-9 and an agonistic antibody to the co-stimulatory receptor GITR (glucocorticoid-induced tumor necrosis factor receptor-related protein) that depletes T reg cells induces synergistic antitumor activity. Gal-9 expression and secretion are promoted by interferon β and γ, and high Gal-9 expression correlates with poor prognosis in multiple human cancers. Our work uncovers a function for PD-1 in exhausted T cell survival and suggests Gal-9 as a promising target for immunotherapy.

A novel STING agonist, CDG SF , ipsilaterally modified with phosphorothioate and fluorine, was synthesized. The phosphorothioate in CDG SF might be a site for covalent conjugation. Injection of CDG SF generated an immunogenic ("hot") tumor microenvironment to suppress melanoma, more efficiently than dithio CDG. In particular, immunization with SARS-CoV-2 spike protein using CDG SF as an adjuvant elicited an exceptionally high antibody titer and a robust T cell response, overcoming the drawbacks of aluminum hydroxide. These results highlighted the therapeutic potential of CDG SF for cancer immunotherapy and the adjuvant potential of the STING agonist in the SARS-CoV-2 vaccine for the first time.

Currently approved immune checkpoint inhibitor therapies targeting the PD-1 and CTLA-4 receptor pathways are powerful treatment options for certain cancers; however, most patients across cancer types still fail to respond. Consequently, there is interest in discovering and blocking alternative pathways that mediate immune suppression. One such mechanism is an upregulation of sialoglycans in malignancy, which has been recently shown to inhibit immune cell activation through multiple mechanisms and therefore represents a targetable glycoimmune checkpoint. Since these glycans are not canonically druggable, we designed an αHER2 antibody-sialidase conjugate that potently and selectively strips diverse sialoglycans from breast cancer cells. In syngeneic breast cancer models, desialylation enhanced immune cell infiltration and activation and prolonged the survival of mice, an effect that was dependent on expression of the Siglec-E checkpoint receptor found on tumor-infiltrating myeloid cells. Thus, antibody-sialidase conjugates represent a promising modality for glycoimmune checkpoint therapy.

Background: The anti-angiogenic fusion protein RBDV-IgG1 Fc (RBDV), which comprises the receptor-binding domain of vascular endothelial growth factor-A (VEGF-A), has shown antitumour effects by reducing angiogenesis in vivo. This study used the cationic lipoplex lipo-PEG-PEI-complex (LPPC) to simultaneously encapsulate both the RBDV targeting protein and the RBDV plasmid (pRBDV) without covalent bonds to assess VEGFR targeting gene therapy in mice with melanoma in vivo., Results: LPPC protected the therapeutic transgene from degradation by DNase, and the LPPC/RBDV complexes could specifically target VEGFR-positive B16-F10 cells both in vitro and in vivo. With or without RBDV protein-targeting direction, the pRBDV-expressing RBDV proteins were expressed and reached a maximal concentration on the 7th day in the sera after transfection in vivo and significantly elicited growth suppression against B16-F10 melanoma but not IgG1 control proteins. In particular, LPPC/pRBDV/RBDV treatment with the targeting molecules dramatically inhibited B16-F10 tumour growth in vivo to provide better therapeutic efficacy than the treatments with gene therapy with IgG1 protein targeting or administration of a protein drug with RBDV., Conclusions: The simultaneous combination of the LPPC complex with pRBDV gene therapy and RBDV protein targeting might be a potential tool to conveniently administer targeted gene therapy for cancer therapy.

Experiments on F1(CBA×C57BL/6) mice with experimental metastatic melanoma B16 F10 showed that single intravenous injection of xenogeneic bone marrow mesenchymal stromal cells (BM-MSC) in a dose of 10 6 cells/mouse significantly increased 100-day survival rate of tumor-bearing animals. In contrast, administration of BM-MSC in a dose of 2×10 6 cells/ mouse reduced survival rates in comparison with the biocontrol (injection of B16 cells alone, 5×10 5 cells/mouse). This phenomenon can be related to in vivo participation of BM-MSC in reprogramming of resident tissue macrophages, including tumor microenvironment, towards pro- (M1) or anti-inflammatory (M2) phenotype. This is indirectly confirmed by the data on switching from activation to inhibition of ROS-producing activity of blood mononuclears and peritoneal macrophages in tumor-bearing mice in the test of luminol-dependent zymosaninduced chemiluminescence.

Background: This study aimed to evaluate the relationship between survivin expression and melanoma after 5-aminolevulinic acid (5-ALA)-mediated sonodynamic therapy., Methods: Immunohistochemistry was used to detect survivin protein expression in human melanoma clinical samples. Subsequently, the effects of 5-ALA-mediated sonodynamic therapy were determined by measuring the volume of melanoma xenografts and the bodyweights of melanoma-bearing nude mice. The MTT assay was used to detect the viability of melanoma B16-F10 cells under the action of 5-ALA-mediated sonodynamic therapy, and Western blotting and PCR were used to detect survivin expression in melanoma cells and in the melanoma-xenograft model., Results: Survivin expression was significantly upregulated in human melanoma tissues compared with that of non-melanoma tissues. In the in vivo case, 5-ALA-mediated sonodynamic therapy significantly delayed tumor growth, prolonged the survival of mice, and inhibited the expression of survivin. In the in vitro case, 5-ALA-mediated sonodynamic therapy inhibited B16-F10 cell proliferation and decreased survivin expression at both protein and mRNA levels., Conclusion: Our results suggest that 5-ALA-mediated sonodynamic therapy inhibited B16-F10 cell proliferation and melanoma-xenograft growth and prolonged survival of melanoma-bearing nude mice, which might be through downregulation of survivin expression.

The use of microneedles has facilitated the painless localized delivery of drugs across the skin. However, their efficacy has been limited by slow diffusion of molecules and often requires external triggers. Herein, an autonomous and degradable, active microneedle delivery platform is introduced, employing magnesium microparticles loaded within the microneedle patch, as the built-in engine for deeper and faster intradermal payload delivery. The magnesium particles react with the interstitial fluid, leading to an explosive-like rapid production of H 2 bubbles, providing the necessary force to breach dermal barriers and enhance payload delivery. The release kinetics of active microneedles is evaluated in vitro by measuring the amount of IgG antibody (as a model drug) that passed through phantom tissue and a pigskin barrier. In vivo experiments using a B16F10 mouse melanoma model demonstrate that the active delivery of anti-CTLA-4 (a checkpoint inhibitor drug) results in greatly enhanced immune response and significantly longer survival. Moreover, spatially resolved zones of active and passive microneedles allow a combinatorial rapid burst response along with slow, sustained release, respectively. Such versatile and effective autonomous dynamic microneedle delivery technology offers considerable promise for a wide range of therapeutic applications, toward a greatly enhanced outcome, convenience, and cost., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Antibodies targeting the T-cell immune checkpoint cytotoxic T-lymphocyte antigen-4 (CTLA4) enhance the effectiveness of radiotherapy for melanoma patients, but many remain resistant. To further improve response rates, we explored combining anti-CTLA4 blockade with antisense suppression of CD47, an inhibitory receptor on T cells that limit T-cell receptor signaling and killing of irradiated target cells. Human melanoma data from The Cancer Genome Atlas revealed positive correlations between CD47 mRNA expression and expression of T-cell regulators including CTLA4 and its counter receptors CD80 and CD86. Antisense suppression of CD47 on human T cells in vitro using a translational blocking morpholino (CD47 m) alone or combined with anti-CTLA4 enhanced antigen-dependent killing of irradiated melanoma cells. Correspondingly, the treatment of locally irradiated B16F10 melanomas in C57BL/6 mice using combined blockade of CD47 and CTLA4 significantly increased the survival of mice relative to either treatment alone. CD47 m alone or in combination with anti-CTLA4 increased CD3 + T-cell infiltration in irradiated tumors. Anti-CTLA4 also increased CD3 + and CD8 + T-cell infiltration as well as markers of NK cells in non-irradiated tumors. Anti-CTLA4 combined with CD47 m resulted in the greatest increase in intratumoral granzyme B, interferon-γ, and NK-cell marker mRNA expression. These data suggest that combining CTLA4 and CD47 blockade could provide a survival benefit by enhancing adaptive T- and NK-cell immunity in irradiated tumors.

Mammals evolved in the face of fluctuating food availability. How the immune system adapts to transient nutritional stress remains poorly understood. Here, we show that memory T cells collapsed in secondary lymphoid organs in the context of dietary restriction (DR) but dramatically accumulated within the bone marrow (BM), where they adopted a state associated with energy conservation. This response was coordinated by glucocorticoids and associated with a profound remodeling of the BM compartment, which included an increase in T cell homing factors, erythropoiesis, and adipogenesis. Adipocytes, as well as CXCR4-CXCL12 and S1P-S1P 1 R interactions, contributed to enhanced T cell accumulation in BM during DR. Memory T cell homing to BM during DR was associated with enhanced protection against infections and tumors. Together, this work uncovers a fundamental host strategy to sustain and optimize immunological memory during nutritional challenges that involved a temporal and spatial reorganization of the memory pool within "safe haven" compartments., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Regulatory T (T reg ) cells are essential for peripheral tolerance and rely on the transcription factor (TF) Foxp3 for their generation and function. Several other TFs are critical for the T reg cell program. We found that mice deficient in Bcl11b TF solely in T reg cells developed fatal autoimmunity, and Bcl11b-deficient T reg cells had severely altered function. Bcl11b KO T reg cells showed decreased functional marker levels in homeostatic conditions, inflammation, and tumors. Bcl11b controlled expression of essential T reg program genes at steady state and in inflammation. Bcl11b bound to genomic regulatory regions of T reg program genes in both human and mouse T reg cells, overlapping with Foxp3 binding; these genes showed altered chromatin accessibility in the absence of Bcl11b. Additionally, Bcl11b restrained myeloid and NK cell programs in T reg cells. Our study provides new mechanistic insights on the T reg cell program and identity control, with major implications for therapies in autoimmunity and cancer.

During the last 3 decades, there has been a slow advance to obtain new treatments for malignant melanoma that improve patient survival. In this work, we present a systematic study focused on the antiproliferative and antitumour effect of AgNPs. These nanoparticles are fully characterized, are coated with polyvinylpyrrolidone (PVP), and have an average size of 35 ± 15 nm and a metallic silver content of 1.2% wt. Main changes on cell viability, induction of apoptosis and necrosis, and ROS generation were found on B16-F10 cells after six hours of exposure to AgNPs (IC 50 = 4.2  μ g/mL) or Cisplatin (IC 50 = 2.0  μ g/mL). Despite the similar response for both AgNPs and Cisplatin on antiproliferative potency (cellular viability of 53.95 ± 1.88 and 53.62 ± 1.04) and ROS production (20.27 ± 1.09% and 19.50 ± 0.35%), significantly different cell death pathways were triggered. While AgNPs induce only apoptosis (45.98 ± 1.88%), Cisplatin induces apoptosis and necrosis at the same rate (22.31 ± 1.72% and 24.07 ± 1.10%, respectively). In addition to their antiproliferative activity, in vivo experiments showed that treatments of 3, 6, and 12 mg/kg of AgNPs elicit a survival rate almost 4 times higher ( P < 0.05) compared with the survival rate obtained with Cisplatin (2 mg/kg). Furthermore, the survivor mice treated with AgNPs do not show genotoxic damage determined by micronuclei frequency quantification on peripheral blood cells. These results exhibit the remarkable antitumour activity of a nongenotoxic AgNP formulation and constitute the first advance toward the application of these AgNPs for melanoma treatment, which could considerably reduce adverse effects provoked by currently applied chemotherapeutics., Competing Interests: The authors declare that there is no conflict of interest regarding the publication of this paper.

Myeloid cells contribute to tumor progression, but how the constellation of receptors they express regulates their functions within the tumor microenvironment (TME) is unclear. We demonstrate that Fcmr (Toso), the putative receptor for soluble IgM, modulates myeloid cell responses to cancer. In a syngeneic melanoma model, Fcmr ablation in myeloid cells suppressed tumor growth and extended mouse survival. Fcmr deficiency increased myeloid cell population density in this malignancy and enhanced anti-tumor immunity. Single-cell RNA sequencing of Fcmr-deficient tumor-associated mononuclear phagocytes revealed a unique subset with enhanced antigen processing/presenting properties. Conversely, Fcmr activity negatively regulated the activation and migratory capacity of myeloid cells in vivo, and T cell activation by bone marrow-derived dendritic cells in vitro. Therapeutic targeting of Fcmr during oncogenesis decreased tumor growth when used as a single agent or in combination with anti-PD-1. Thus, Fcmr regulates myeloid cell activation within the TME and may be a potential therapeutic target.

Since mannose receptors (MRs) are expressed on the surfaces of dendritic cells (DCs), the most professional antigen presenting cells in our body, DNA vaccine carriers containing either covalently grafted mannosyl- or mannose-mimicking shikimoyl-ligands are being increasingly used in ex vivo DC-transfection based DNA vaccination. To this end, we have recently demonstrated that ex vivo immunization of mice with liposomes of shikimoylated cationic amphiphiles containing a 6-amino hexanoic acid spacer group in the head-group region in complexation with melanoma antigen (MART1) encoded DNA vaccine (pCMV-MART1) induces long lasting anti-melanoma immune responses (C. Voshavar, et al., J. Med. Chem., 2017, 60, 1605-1610). This finding prompted us to examine, in the present investigation, the efficacies of gold nanoparticles conjugated to the mannose-mimicking shikimoyl ligand (SL) via a 6-amino hexane thiol spacer (AuNPs-SL) for use in ex vivo DC-transfection based genetic immunization. Herein, we report on the design, synthesis, physico-chemical characterization and bioactivities of AuNPs-SL. Dynamic light scattering and transmission electron microscopy studies revealed the hydrodynamic diameters of theAuNPs-SL nanoconjugates to be within the range of 23-44 nm and their surface potentials within the range of 9-28 mV. MTT-assay showed the non-cytotoxic nature of AuNPs-SL and the findings in the electrophoretic gel retardation assays revealed strong DNA binding properties of the AuNPs-SL. Importantly, subcutaneous immunization of C57BL/6J mice with DCs ex vivo transfected with an electrostatic complex of AuNPs-SL & melanoma antigen (MART1) encoded DNA vaccine (p-CMV-MART1) induced a long lasting (100 days) anti-tumor immune response in immunized mice upon subsequent challenge with a lethal dose of melanoma. Notably, mice immunized with either autologous mbmDCs ex vivo pre-transfected with nanoplexes of shikimoylated AuNPs-SL & an irrelevant pCMV-SPORT-β-gal plasmid (without having encoded melanoma antigen) or untransfected DCs showed no lasting protection against subsequent tumor challenge. The presently described shikimoyl-decorated gold nanoparticles (AuNPs-SL) are expected to find future use in ex vivo DC-transfection based genetic immunization against cancer and other infectious diseases.

Melanoma is a highly aggressive skin cancer. A paclitaxel formulation of solid lipid nanoparticles modified with Tyr-3-octreotide (PSM) is employed to treat melanoma that highly expresses somatostatin receptors (SSTRs). PSM exerts more apoptotic and anti-invasive effects in B16F10 mice melanoma cells as compared to dacarbazine (DTIC), an approved chemotherapeutic drug for treating aggressive melanoma. Besides, PSM induces one of the biomarkers of immunogenic cell death in vitro and in vivo as confirmed by calreticulin exposure on the B16F10 cell surface. We observed a significant number of CD8 positive T cells in the tumor bed of the PSM treated group. As a result, PSM effectively reduces tumor volume in vivo as compared to DTIC. PSM also induces a favorable systemic immune response as determined in the spleen and sera of the treated animals. Importantly, PSM can reduce the number of nodule formations in the experimental lung metastasis model. Our experimentations indicate that the metronomic PSM exhibits remarkable anti-melanoma activities without any observable toxicity. This immune modulation behavior of PSM can be exploited for the therapy of melanoma and probably for other malignancies.

Immune checkpoint blockade therapy has shifted the paradigm for cancer treatment. However, the majority of patients lack effective responses due to insufficient T cell infiltration in tumors. Here we show that expression of mitochondrial uncoupling protein 2 (UCP2) in tumor cells determines the immunostimulatory feature of the tumor microenvironment (TME) and is positively associated with prolonged survival. UCP2 reprograms the immune state of the TME by altering its cytokine milieu in an interferon regulatory factor 5-dependent manner. Consequently, UCP2 boosts the conventional type 1 dendritic cell- and CD8 + T cell-dependent anti-tumor immune cycle and normalizes the tumor vasculature. Finally we show, using either a genetic or pharmacological approach, that induction of UCP2 sensitizes melanomas to programmed cell death protein-1 blockade treatment and elicits effective anti-tumor responses. Together, this study demonstrates that targeting the UCP2 pathway is a potent strategy for alleviating the immunosuppressive TME and overcoming the primary resistance of programmed cell death protein-1 blockade.

Intracellular lipopolysaccharide (LPS) triggers the non-canonical inflammasome pathway, resulting in pyroptosis of innate immune cells. In addition to its well-known proinflammatory role, LPS can directly cause regression of some tumors, although the underlying mechanism has remained unknown. Here we show that secretoglobin(SCGB)3A2, a small protein predominantly secreted in airways, chaperones LPS to the cytosol through the cell surface receptor syndecan-1; this leads to pyroptotic cell death driven by caspase-11. SCGB3A2 and LPS co-treatment significantly induced pyroptosis of macrophage RAW264.7 cells and decreased cancer cell proliferation in vitro, while SCGB3A2 treatment resulted in reduced progression of xenograft tumors in mice. These data suggest a conserved function for SCGB3A2 in the innate immune system and cancer cells. These findings demonstrate a critical role for SCGB3A2 as an LPS delivery vehicle; they reveal one mechanism whereby LPS enters innate immune cells leading to pyroptosis, and they clarify the direct effect of LPS on cancer cells., Competing Interests: SY, YC, MM, TT, MY, LX, RC, SK No competing interests declared, AP ALP is an employee of APCBio Innovations and has a 51% ownership interest in APCBio Innovations, which has an interest in commercializing the rhSCGB3A2. US Patent Application (No. 62/619,511) was filed for the work described in this manuscript.

Purpose: Hypofractionated radiation therapy (hRT) combined with immune checkpoint blockade can induce T-cell-mediated local and abscopal antitumor effects. We had previously observed peak levels of tumor-infiltrating lymphocytes (TILs) between days 5 and 8 after hRT. Because TILs are regarded as radiosensitive, hRT schedules extending into this period might be less immunogenic, prompting us to compare clinically relevant, short and extended schedules with equivalent biologically effective doses combined with anti-programmed cell death 1 (PD1) antibody treatment., Methods and Materials: In mice bearing 2 B16-CD133 melanoma tumors, the primary tumor was irradiated with 3 × 9.18 Gy in 3 or 5 days or with 5 × 6.43 Gy in 10 days; an anti-PD1 antibody was given weekly. The mice were monitored for tumor growth and survival. T-cell responses were determined on days 8 and 15 of treatment. The role of regional lymph nodes was studied by administering FTY720, which blocks lymph node egress of activated T cells. Tumor growth measurements after combination treatment using short or extended hRT and control treatment were also performed in the wild-type B16 melanoma and 4T1 breast carcinoma models., Results: In the B16-CD133 model, growth inhibition of irradiated primary and nonirradiated secondary tumors and overall survival were similar with all 3 hRT/anti-PD1 combinations, superior to hRT and anti-PD1 monotherapy, and was strongly dependent on CD8 + T cells. TIL infiltration and local and systemic tumor-specific CD8 + T-cell responses were also similar, regardless of whether short or extended hRT was used. Administration of FTY720 accelerated growth of both primary and secondary tumors, strongly reduced their TIL infiltration, and increased tumor-specific CD8 + T cells in the lymph nodes draining the irradiated tumor. In the 4T1 model, local and abscopal tumor control was also similar, regardless of whether short or extended hRT was used, although the synergy between hRT and anti-PD1 was weaker. No synergies were found in the B16 wild-type model lacking an exogenous antigen., Conclusions: Our data suggest that combination therapy with hRT schedules extending into the period during which treatment-induced T cells infiltrate the irradiated tumor can provoke local and systemic antitumor effects similar to those with therapy using shorter schedules, if the regional lymph nodes supply sufficient tumor-specific T cells. This has implications for planning clinical RT/immune checkpoint blockade trials., (Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.)

Small interfering RNA (siRNA) represents a promising class of inhibitors in both fundamental research and the clinic. Numerous delivery vehicles have been developed to facilitate siRNA delivery. Nevertheless, achieving highly potent RNA interference (RNAi) toward clinical translation requires efficient formation of RNA-induced gene-silencing complex (RISC) in the cytoplasm. Here we coencapsulate siRNA and the central RNAi effector protein Argonaute 2 (Ago2) via different delivery carriers as a platform to augment RNAi. The physical clustering between siRNA and Ago2 is found to be indispensable for enhanced RNAi. Moreover, by utilizing polyamines bearing the same backbone but distinct cationic side-group arrangements of ethylene diamine repeats as the delivery vehicles, we find that the molecular structure of these polyamines modulates the degree of siRNA/Ago2-mediated improvement of RNAi. We apply this strategy to silence the oncogene STAT3 and significantly prolong survival in mice challenged with melanoma. Our findings suggest a paradigm for RNAi via the synergistic coassembly of RNA with helper proteins., Competing Interests: Conflict of interest statement: A provisional US patent application (62/505,430) on this work has been filed.

Purpose: Dendritic cell (DC)-based cancer vaccines is a newly emerging and potent form of immune therapy. As for any new technology, there are still considerable challenges that need to be addressed. Here, we investigate the antitumor potential of a novel liposomal vaccine, M/CpG-ODN-TRP2-Lipo., Methods: We developed a vaccination strategy by assembling the DC-targeting mannose and immune adjuvant CpG-ODN on the surface of liposomes, which were loaded with melanoma-specific TRP2 180-188 peptide as liposomal vaccine. M/CpG-ODN-TRP2-Lipo treatment was used to intendedly induce activation of DCs and antitumor- specific immune response in vivo., Results: Our results demonstrated in vitro that the prepared liposomal particles were efficiently taken up by DCs. This uptake led to an enhanced activation of DCs, as measured by the upregulation of MHC II, CD80, and CD86. Furthermore, M/CpG-ODN-TRP2-Lipo effectively inhibited the growth of implanted B16 melanoma and prolonged the survival of mice. This therapy significantly reduced the number of myeloid-derived suppressor cells (MDSCs) and regulatory T cells, while simultaneously increasing the number of activated T cells, tumor antigen-specific CD8 + cytotoxic T cells, and interferon-γ-producing cells. At the same time, it was found to suppress tumor angiogenesis and tumor cell proliferation, as well as up-regulate their apoptosis. Interestingly, MyD88-knockout mice had significantly shorter median survival times compared to wild-type mice following the administration of M/CpG-ODN-TRP2-Lipo., Conclusions: The results suggested that the antitumor activities of the vaccine partially rely on the Myd88 signaling pathway. Interestingly, compared to whole tumor cell lysate-based vaccine, M/CpG-ODN-TRP2-Lipo, tumor specific antigen peptide-based vaccine, improved survival of tumor-bearing mice as well as enhanced their antitumor responses. All in all, we describe a novel vaccine formulation, M/CpG-ODN-TRP2-Lipo, with the aim of improving antitumor responses by alleviating the immunosuppressive environment in tumors., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Nano-prodrugs usually involve a multistep synthesis which largely compromises their benefits. Here, a smart nano-prodrug platform with reactive drug loading, superb stability, and triggered drug release is reported for targeted melanoma therapy. cRGD-decorated polymersomal mertansine prodrug (cRGD-PS-DM1) is readily fabricated from cRGD-functionalized poly(ethylene glycol)-b-poly(trimethylene carbonate-co-dithiolane trimethylene carbonate) with simultaneous loading of mertansine (DM1) via thiol-disulfide exchange reaction and disulfide cross-linking of polymersomal membrane. cRGD-PS-DM1 exhibits a size of ≈100 nm, little drug leakage, and fast DM1 release in the presence of 2 × 10 -3 -10 × 10 -3 m glutathione. Tetrazolium-based colorimetric assay (MTT) and confocal microscopy studies confirm effective homing of cRGD-PS-DM1 to α v β 3 overexpressing B16F10 melanoma cells. Notably, the in vivo studies show that cRGD-PS-DM1 has a greatly improved toleration as compared with free DM1 and effectively inhibits tumor growth and extends the survival time of B16F10 melanoma-bearing mice. cRGD-PS-DM1 nano-prodrug with reactive drug loading and multifunction provides an advanced nanomedicine for cancer therapy., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: The epidermal application of the Toll Like Receptor 7 agonist imiquimod and a T-cell peptide epitope (transcutaneous immunization, TCI) mediates systemic peptide-specific cytotoxic T-cell (CTL) responses and leads to tumor protection in a prophylactic tumor setting. However, it does not accomplish memory formation or permanent defiance of tumors in a therapeutic set-up. As a distinct immunologic approach, CTLA-4 blockade augments systemic immune responses and has shown long-lasting effects in preclinical experiments as well as in clinical trials., Objective: The study investigates the vaccination capacity of TCI in combination with the checkpoint inhibitor CTLA-4 in matters of primary response, memory formation and tumor protection and characterizes the role of regulatory T cells (Tregs)., Methods: After performing TCI with IMI-Sol (containing 5% Imiquimod) and the model epitope SIINFEKL, 6-8 week old C57BL/6 mice received anti-CTLA-4 antibody either s.c or i.p. The CTL responses and frequency of peptide specific CD8 + T-cells were then evaluated on day 8. To determine anti-tumor effects, a therapeutic tumor challenge with B16 OVA melanoma was performed., Results: The combination of s.c. anti-CTLA-4 antibody and TCI leads to an enhanced systemic cytotoxic response, to memory formation and allows significantly improved survival in a tumor setting with B16 OVA melanoma. Towards the mechanism, we show that in this vaccination protocol the CTLA-4 antibody acts mainly Treg-independent., Conclusion: We demonstrate that the combination of TCI with IMI-Sol and anti-CTLA-4 can confer potent immune responses and tumor-protection. These results might contribute to the development of advanced vaccination approaches targeting tumors or persistent infectious diseases., (Copyright © 2017 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

CD40-activating immunotherapy has potent antitumor effects due to its ability to activate dendritic cells and induce cytotoxic T-cell responses. However, its efficacy is limited by immunosuppressive cells in the tumor and by endothelial anergy inhibiting recruitment of T-cells. Here, we show that combining agonistic CD40 monoclonal antibody (mAb) therapy with vascular targeting using the tyrosine kinase inhibitor sunitinib decreased tumor growth and improved survival in B16.F10 melanoma and T241 fibrosarcoma. Treatment of tumor-bearing mice with anti-CD40 mAb led to increased activation of CD11c+ dendritic cells in the tumor draining lymph node, while sunitinib treatment reduced vessel density and decreased accumulation of CD11b+Gr1+ myeloid derived suppressor cells. The expression of ICAM-1 and VCAM-1 adhesion molecules was up-regulated on tumor endothelial cells only when anti-CD40 mAb treatment was combined with sunitinib. This was associated with enhanced intratumoral infiltration of CD8+ cytotoxic T-cells. Our results show that combining CD40-stimulating immunotherapy with sunitinib treatment exerts potent complementary antitumor effects mediated by dendritic cell activation, a reduction in myeloid derived suppressor cells and increased endothelial activation, resulting in enhanced recruitment of cytotoxic T-cells., Competing Interests: S.M. Mangsbo reports receiving a commercial research grant from Alligator Bioscience and has a royalty agreement with Alligator Bioscience on patent US20130004483 A1, for which she is a co-inventor. S.M. Mangsbo is the founder, shareholder, board member and previous CEO of Immuneed, Inc. No potential conflicts of interest were disclosed by the other authors.

DNA methyltransferase DNMT3B is frequently overexpressed in tumor cells and plays important roles during the formation and progression of several cancer types. However, the specific signaling pathways controlled by DNMT3B in cancers, including melanoma, are poorly understood. Here, we report that DNMT3B plays a pro-tumorigenic role in human melanoma and that DNMT3B loss dramatically suppresses melanoma formation in the Braf/Pten mouse melanoma model. Loss of DNMT3B results in hypomethylation of the miR-196b promoter and increased miR-196b expression, which directly targets the mTORC2 component Rictor. Loss of RICTOR in turn prevents mTORC2 activation, which is critical for melanoma formation and growth. These findings establish Dnmt3b as a regulator of melanoma formation through its effect on mTORC2 signaling. Based on these results, DNMT3B is a potential therapeutic target in melanoma., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Oncolytic reovirus can be delivered both systemically and intratumorally, in both preclinical models and in early phase clinical trials. Reovirus has direct oncolytic activity against a variety of tumor types and antitumor activity is directly associated with immune activation by virus replication in tumors. Immune mechanisms of therapy include both innate immune activation against virally infected tumor cells, and the generation of adaptive antitumor immune responses as a result of in vivo priming against tumor-associated antigens. We tested the combination of local oncolytic reovirus therapy with systemic immune checkpoint inhibition. We show that treatment of subcutaneous B16 melanomas with a combination of intravenous (i.v.) anti-PD-1 antibody and intratumoral (i.t.) reovirus significantly enhanced survival of mice compared to i.t. reovirus (P < 0.01) or anti-PD-1 therapy alone. In vitro immune analysis demonstrated that checkpoint inhibition improved the ability of NK cells to kill reovirus-infected tumor cells, reduced T(reg) activity, and increased the adaptive CD8(+) T-cell-dependent antitumor T-cell response. PD-1 blockade also enhanced the antiviral immune response but through effector mechanisms which overlapped with but also differed from those affecting the antitumor response. Therefore, combination with checkpoint inhibition represents a readily translatable next step in the clinical development of reovirus viroimmunotherapy.

Calorie restriction or a low-carbohydrate diet (LCD) can increase life span in normal cells while inhibiting carcinogenesis. Various phytochemicals also have calorie restriction-mimetic anticancer properties. We investigated whether an isocaloric carbohydrate-restriction diet and AMP-activated protein kinase (AMPK)-activating phytochemicals induce synergic tumor suppression. We used a mixture of AMPK-activating phytochemical extracts including curcumin, quercetin, catechins, and resveratrol. Survival analysis was carried out in a B16F10 melanoma model fed a control diet (62.14% kcal carbohydrate, 24.65% kcal protein and 13.2% kcal fat), a control diet with multiple phytochemicals (MP), LCD (16.5, 55.2, and 28.3% kcal, respectively), LCD with multiple phytochemicals (LCDmp), a moderate-carbohydrate diet (MCD, 31.9, 62.4, and 5.7% kcal, respectively), or MCD with phytochemicals (MCDmp). Compared with the control group, MP, LCD, or MCD intervention did not produce survival benefit, but LCDmp (22.80±1.58 vs. 28.00±1.64 days, P=0.040) and MCDmp (23.80±1.08 vs. 30.13±2.29 days, P=0.008) increased the median survival time significantly. Suppression of the IGF-1R/PI3K/Akt/mTOR signaling, activation of the AMPK/SIRT1/LKB1pathway, and NF-κB suppression were the critical tumor-suppression mechanisms. In addition, SIRT1 suppressed proliferation of the B16F10 and A375SM cells under a low-glucose condition. Alterations in histone methylation within Pten and FoxO3a were observed after the MCDmp intervention. In the transgenic liver cancer model developed by hydrodynamic transfection of the HrasG12V and shp53, MCDmp and LCDmp interventions induced significant cancer-prevention effects. Microarray analysis showed that PPARα increased with decreased IL-6 and NF-κB within the hepatocytes after an MCDmp intervention. In conclusion, an isocaloric carbohydrate-restriction diet and natural AMPK-activating agents induce synergistic anticancer effects. SIRT1 acts as a tumor suppressor under a low-glucose condition.

Trifunctional bispecific antibodies (trAb) are novel anticancer drugs that recruit and activate different types of immune effector cells at the targeted tumor. Thus, tumor cells are effectively eliminated and a long-lasting tumor-specific T-cell memory is induced. The trAb Ektomab is directed against human CD3 on T cells and the tumor-associated ganglioside GD2, which is an attractive target for immunotherapy of melanoma in humans. To optimize clinical applicability, we studied different application routes with respect to therapeutic efficacy and tolerability by using the surrogate trAb Surek (anti-GD2 × anti-murine CD3) and a murine melanoma engineered to express GD2. We show that subcutaneous injection of the trAb is superior to the intravenous delivery pathway, which is the standard application route for therapeutic antibodies. Despite lower plasma levels after subcutaneous administration, the same tumor-protective potential was observed in vivo compared with intravenous administration of Surek. However, subcutaneously delivered Surek showed better tolerability. This could be explained by a continuous release of the antibody leading to constant plasma levels and a delayed induction of proinflammatory cytokines. Importantly, the induction of counter-regulatory mechanisms was reduced after subcutaneous application. These findings are relevant for the clinical application of trifunctional bispecific antibodies and, possibly, also other immunoglobulin constructs. Mol Cancer Ther; 14(8); 1877-83. ©2015 AACR., (©2015 American Association for Cancer Research.)

Brucella Lumazine Synthase (BLS) is a highly immunogenic decameric protein which can accept the fusion of foreign proteins at its ten N-termini. These chimeras are very efficient to elicit systemic and oral immunity without adjuvants. BLS signaling via Toll-Like Receptor 4 (TLR4) regulates innate and adaptive immune responses, inducing dendritic cell maturation and CD8(+) T-cell cytotoxicity. In this work we study the effect induced by BLS in TLR4-expressing B16 melanoma. In order to evaluate the effectiveness of BLS as a preventive vaccine, C57BL/6J mice were immunized with BLS or BLS-OVA, and 35 days later were subcutaneously inoculated with B16-OVA melanoma. BLS or BLS-OVA induced a significant inhibition of tumor growth, and 50% of mice immunized with the highest dose of BLS did not develop visible tumors. This effect was not observed in TLR4-deficient mice. For treatment experiments, mice were injected with BLS or BLS-OVA 2 days after the inoculation of B16 cells. Both treatments induced significant and equal tumor growth delay and increased survival. Moreover, BLS and BLS-OVA stimulation were also effective in TLR4-deficient mice. In order to study whether BLS has a direct effect on tumor cells, B16 cells were preincubated with BLS, and after 48h, cells were inoculated. Tumors induced by BLS-stimulated cells had inhibited growth and survival was increased. In the BLS group, 40% of mice did not develop tumors. This effect was abolished by the addition of TLR4/MD2 blocking antibody to cells before BLS stimulation. Our work demonstrates that BLS immunization induces a preventive antitumor response that depends on mice TLR4. We also show that BLS generates a therapeutic effect in mice inoculated with B16 cells. Our results show that BLS acts directly in cultured tumor cells via TLR4, highly suggesting that BLS elicits its therapeutic effects acting on the TLR4 from B16 melanoma cells.

The development of therapeutic vaccines for treatment of established cancer has proven challenging. Cancer vaccines not only need to induce a robust tumor Ag-specific immune response but also need to overcome the tolerogenic and immunosuppressive microenvironments that exist within many solid cancers. ISCOMATRIX adjuvant (ISCOMATRIX) is able to induce both tumor Ag-specific cellular and Ab responses to protect mice against tumor challenge, but this is insufficient to result in regression of established solid tumors. In the current study, we have used B16-OVA melanoma, Panc-OVA pancreatic, and TRAMP-C1 prostate cancer mouse tumor models to test therapeutic efficacy of ISCOMATRIX vaccines combined with other immune modulators. The coadministration of an ISCOMATRIX vaccine with the TLR3 agonist, polyinosinic-polycytidylic acid, and TLR9 agonist, CpG, reduced tumor growth in all tumor models and the presence of ISCOMATRIX in the formulation was critical for the therapeutic efficacy of the vaccine. This vaccine combination induced a robust and multifunctional CD8(+) T cell response. Therapeutic protection required IFN-γ and CD8(+) T cells, whereas NK and CD4(+) T cells were found to be redundant. ISCOMATRIX vaccines combined with TLR3 and TLR9 agonists represent a promising cancer immunotherapy strategy., (Copyright © 2015 by The American Association of Immunologists, Inc.)

Tumor vessels are an attractive target for cancer therapy, including metastasis treatment. Angiogenesis inhibitors targeting the VEGF signalling pathway have proven to be efficacious in preclinical cancer models and in clinical trials. However, angiogenesis inhibition concomitantly elicits tumor adaptation and progression to stages of greater malignancy, with heightened invasiveness and in some cases increased distant metastasis. Here, we investigated whether NGR-TNF, a vascular targeting agent in phase III clinical development, coupling the CNGRCG angiogenic vessel-homing peptide with TNF-α, has an effect on metastasis in a model of murine breast cancer, which spontaneously metastasize to lungs, and on the growth of experimental melanoma lung metastasis. We report that NGR-TNF does not increase cancer invasiveness, as other antiangiogenics agents do, but controls metastatic growth in both models, both when administered as primary treatment and in adjuvant settings, improving the overall survival of metastasis-bearing mice.

Angiogenesis, activation of metastasis and avoidance of immune destruction are important for cancer progression. These biological capabilities are, apart from cancer cells, mediated by different cell types, including endothelial, haematopoietic progenitor and myeloid-derived suppressor cells. We show here that all these cell types frequently express the Wilms' tumour suppressor Wt1, which transcriptionally controls expression of Pecam-1 (CD31) and c-kit (CD117). Inducible conditional knockout of Wt1 in endothelial, haematopoietic and myeloid-derived suppressor cells is sufficient to cause regression of tumour vascularization and an enhanced immune response, leading to decreased metastasis, regression of established tumours and enhanced survival. Thus, Wt1 is an important regulator of cancer growth via modulation of tumour vascularization, immune response and metastasis formation.

Electroporation (EP) is a method used to physically deliver therapeutic molecules such as plasmid DNA directly to tissues. It has been used safely and successfully in clinical studies and preclinical cancer models to deliver genes to a variety of tissues. In cancer research cytokine therapy is emerging as a promising tool that can be used to boost the host response to tumor antigens. The delivery of cytokines as recombinant proteins can result in toxicity and other adverse effects; however the delivery of cytokine genes using EP has been shown to be safe and effective. Interleukin 15 (IL-15) is a cytokine that promotes the innate as well as the adaptive immune response to cancer cells and bacterial pathogens. In this study we used EP to deliver a human IL-15 plasmid (phIL-15) directly to tumors to examine its anti-cancer effects. B16.F10 melanoma tumors were induced in C57BL/6J mice and phIL-15 was delivered three times over the course of a week. Expression of the transgene, tumor volume, long-term survival and resistance to challenge were monitored in these animals. Delivery of IL-15 plasmid by EP resulted in increased IL-15 expression within the tumor compared to the injection only control. This expression peaked at 12 to 18 hours after the first delivery and was sustained at lower levels after the second and third deliveries. The delivery of the phIL-15 resulted in tumor regression, long-term survival and greater protection against tumor recurrence when cancer cells were reintroduced compared to control plasmid. From these results we can conclude that the delivery of IL-15 plasmid to tumors using EP is a promising avenue to investigate for its anti-tumor effects, however more work needs to be done to increase the stability of the gene once it is delivered and to elucidate the anti-tumor mechanism.

Platinum coordination complexes represent an important class of anti-tumor agents. Due to recognized drawbacks, research into other types of metallodrugs has been diversified with the aim of finding new chemical entities with alternative mechanisms of action to overcome classical chemoresistance. P5 and DP1, two closely related ferrocenyl complexes bearing a similar ferrocenyl-ene-phenyl motif and displaying marked differences in their conformations and oxidation state versatility, were assayed in cancer cell models characterized by various sensitivities to pro-apoptotic stimuli. P5 and DP1 exert growth inhibitory effects between 0.5 and 10 μM against glioma and melanoma cells including pluripotent stem-like cells. These effects are due, at least partly, to senescence induction with typical SA-β-galactosidase staining and senescence-associated secretory phenotype (SASP) as measured by the secretion of IL-1α, IL-1β, IL-6, IL-8 and TNF-α. Regulation of these cytokines' secretion may be related to AP-1 and other transcription factors unrelated to senescence. An in vivo graft of B16F10 cells after in vitro pre-incubation with DP1 or P5 led to increased survival in mice. In conclusion, P5 and DP1 ferrocenyl complexes induce senescence in various cancer cell models associated with distinct sensitivity to pro-apoptotic stimuli., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Autologous vaccination with tumor-primed dendritic cells increases immune response against tumor, which seems to be improved in host absence of CCR5. Because B-1 lymphocytes modulate the activity of different immune cells, we decided to study their influence in the resistance against murine B16F10 melanoma in a CCR5 deprived environment. Adoptive transfer of peritoneal B-1 CCR5(+/+) lymphocytes to CCR5(-/-) animals inhibited the establishment of lung metastasis and melanoma cell growth, in comparison to saline-treated CCR5(-/-) mice. In loco cell analysis demonstrated that the adoptive transfer of B-1 CCR5(+/+) lymphocytes to CCR5 deficient host was associated with a more intense influx of T CD8(+) to tumor site, indicating that the presence of CCR5(+/+) B-1 cells in the tumor environment induces the migration of T CD8 CCR5(-/-) cells to the implantation site. To corroborate this idea, CCR5(-/-) mice were injected with non B-1 peritoneal cells from wild type (WT) mice before B16F10 inoculation. In this regimen, CCR5(-/-) mice were not protected from tumor growth reinforcing the idea that, in host absence of CCR5, B-1 cells are essential to confer tumor resistance. This work indicates that, in the host absence of CCR5, naive B-1 cells may activate CD8T lymphocytes thereby promoting tumor resistance. Our results strongly suggest that autologous vaccination with B-1 lymphocytes in combination with CCR5 antagonists can be an alternative approach to tumor therapy., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

Optimum clinical protocols require systemic delivery of oncolytic viruses in the presence of an intact immune system. We show that preconditioning with immune modulators, or loading virus onto carrier cells ex vivo, enhances virus-mediated antitumor activity. Our early trials of systemic reovirus delivery showed that after infusion reovirus could be recovered from blood cells--but not from plasma--suggesting that rapid association with blood cells may protect virus from neutralizing antibody. We therefore postulated that stimulation of potential carrier cells directly in vivo before intravenous viral delivery would enhance delivery of cell-associated virus to tumor. We show that mobilization of the CD11b(+) cell compartment by granulocyte macrophage-colony stimulating factor immediately before intravenous reovirus, eliminated detectable tumor in mice with small B16 melanomas, and achieved highly significant therapy in mice bearing well-established tumors. Unexpectedly, cytokine conditioning therapy was most effective in the presence of preexisting neutralizing antibody. Consistent with this, reovirus bound by neutralizing antibody effectively accessed monocytes/macrophages and was handed off to tumor cells. Thus, preconditioning with cytokine stimulated recipient cells in vivo for enhanced viral delivery to tumors. Moreover, preexisting neutralizing antibody to an oncolytic virus may, therefore, even be exploited for systemic delivery to tumors in the clinic.

Mesenchymal stromal cells (MSC) can be exploited as cellular delivery vehicles for the enzymes converting non-toxic prodrugs to toxic substances. Because of their inherent chemoresistance, they exert potent bystander and antitumor effect. Here we show that the human adipose tissue-derived MSC expressing fusion yeast cytosine deaminase::uracil phosphoribosyltransferase (CD-MSC) in combination with 5-fluorocytosine (5FC) mediated a long-term tumor-free survival in the 83.3% of tumor-bearing animals. CD-MSC/5FC treatment induced cytotoxicity against model human melanoma cells EGFP-A375. Only 4% of the therapeutic CD-MSC cells eliminated >98.5% of the tumor cells in vitro. Long-term tumor-free survival was confirmed in 15 out of the 18 animals. However, repeatedly used CD-MSC/5FC therapeutic regimen generated more aggressive and metastatic variant of the melanoma cells EGFP-A375/Rel3. These cells derived from the refractory xenotransplants exhibited increased resistance to the CD-MSC/5FC treatment, altered cell adhesion, migration, tumorigenic and metastatic properties. However, long-term curative effect was achieved by the augmentation of the CD-MSC/5FC regimen along with the inhibition of c-Met/hepatocyte growth factor signaling axis in this aggressive melanoma derivative. In summary, the CD-MSC/5FC regimen can be regarded as a very effective antitumor approach to achieve long-term tumor-free survival as demonstrated on a mouse model of aggressive human melanoma xenografts.

Regulatory T cells (T-regs) can negatively impact tumor antigen-specific immune responses after infiltration into tumor tissue. However, depletion of T-regs can facilitate enhanced anti-tumor responses, thus augmenting the potential for immunotherapies. Here we focus on treating a highly aggressive form of cancer using a murine melanoma model with a poor prognosis. We utilize a combination of T-reg depletion and immunotherapy plasmid DNA delivered into the B16F10 melanoma tumor model via electroporation. Plasmids encoding murine granulocyte macrophage colony-stimulating factor and human B71 were transfected with electroporation into the tumor and transient elimination of T-regs was achieved with CD25-depleting antibodies (PC61). The combinational treatment effectively depleted T-regs compared to the untreated tumor and significantly reduced lung metastases. The combination treatment was not effective in increasing the survival, but only effective in suppression of metastases. These results indicate the potential for combining T-reg depletion with immunotherapy-based gene electrotransfer to decrease systemic metastasis and potentially enhance survival.

The use of a cell-based vaccine composed of autologous whole blood cells loaded with mRNA is described. Mice immunized with whole blood cells loaded with mRNA encoding antigen develop anti-tumor immunity comparable to DC-RNA immunization. This approach offers a simple and affordable alternative to RNA-based cellular therapy by circumventing complex, laborious and expensive ex vivo manipulations required for DC-based immunizations., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Dendritic cell (DC)-based vaccine approaches are being actively evaluated for developing immunotherapeutic agents against cancers. In this study, we investigated the use of engineered DCs expressing transgenic tumor-associated antigen hgp100 and the regulatory cytokine interleukin-21, namely DC-hgp100/mIL-21, as a therapeutic vaccine against melanoma. Tumor-bearing mice were injected intratumorally with transgenic DCs followed by three booster injections. Transgenic DC-hgp100/mIL-21 showed significant reduction in primary tumor growth and metastasis compared with DC-hgp100 alone and DC-mIL-21 alone. In vivo depletion of specific immune cell types (CD8(+) T, CD4(+) T and Natural killer (NK)-1.1(+) cells) effectively blocked the protective effect of this combinational vaccine. In adoptive transfer experiments, a survival rate of nearly 90% was observed at 60 days post-tumor inoculation for the combinational vaccine group. In contrast, all mice in the DC-hgp100 and DC-mIL-21-only groups died within 43-46 days after tumor challenge. Considerably increased levels of interferon (IFN)-γ, tumor necrosis factor (TNF)-α, granulocyte macrophage colony-stimulating factor (GM-CSF) and cytotoxic T lymphocytes (CTLs) were detected with the combination vaccine group compared with other individual treatment groups. In comparison with the DC-hgp100 or mIL-21 groups, the combinational DC-hgp100/mIL-21 vaccine also drastically suppressed the myeloid-derived suppressor cells (MDSCs) and T-regulatory (Treg) cell populations. Our findings suggest that a combinational DC- and gene-based hgp100 and mIL-21 vaccine therapy strategy warrants further evaluation as a clinically relevant cancer vaccine approach for human melanoma patients.

Newcastle disease virus (NDV) is an intrinsically tumor-specific virus, several clinical trials have reported that mesogenic NDV is a safe and effective agent for human cancer therapy. Interleukin 2 (IL2) is a cytokine that stimulates T cell propagation to trigger innate and adaptive immunity. IL2 has been used for cancer therapy and has achieved curative effects. In this study, a recombinant NDV LaSota strain expressing human interleukin 2 (rLaSota/IL2) was generated. The ability of rLaSota/IL2 to express human IL2 was detected in the infected tumor cells. In addition, the activity of IL2 was analyzed. The antitumor potential of rLaSota/IL2 was studied by xenograph mice carrying H22 and B16-F10 cells. Tumor-specific CD4(+) and CD8(+) T cells and MHC II were also analyzed in the two tumor-bearing models. Our study showed that rLaSota/IL2 significantly stimulated tumor-specific cytotoxic T-lymphocyte (CTL) responses and increased regulatory CD4(+) and cytotoxic CD8(+) T cells proliferation. The treatment with rLaSota/IL2 led to tumor regression in tumor-bearing mice and prolonged the survival of tumor-bearing mice. Furthermore, tumor challenging experiments demonstrated that rLaSota/IL2 invoked mice a unique capacity to remember a pathogen through the generation of memory T cells, which protect the host in the event of reinfection and form adaptive immune system. The result indicates that tumor-infiltrating CD4(+) T regulatory cells may denote the effective regression of tumors. Taken together, rLaSota/IL2 has potential for immunotherapy and oncolytic therapy of cancers and may be an ideal candidate for clinical application in future cancer therapy., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Melanoma is a rapidly growing and highly metastatic cancer with high mortality rates, for which a resolutive treatment is lacking. Identification of novel therapeutic strategies and biomarkers of tumour stage is thus of particular relevance. We report here on a novel biomarker and possible candidate therapeutic target, the sphingolipid metabolising enzyme acid sphingomyelinase (A-SMase). A-SMase expression correlates inversely with tumour stage in human melanoma biopsies. Studies in a mouse model of melanoma and on cell lines derived from mouse and human melanomas demonstrated that A-SMase levels of expression actually determine the malignant phenotype of melanoma cells in terms of pigmentation, tumour progression, invasiveness and metastatic ability. The action of A-SMase is mediated by the activation of the extracellular signal-regulated kinase, the subsequent proteasomal degradation of the Microphtalmia-associated transcription factor (Mitf) and inhibition of cyclin-dependent kinase 2, Bcl-2 and c-Met, downstream targets of Mitf involved in tumour cell proliferation, survival and metastatisation.

Redirecting Ag specificity by transfer of TCR genes into PBLs is an attractive method to generate large numbers of cytotoxic T cells for immunotherapy of cancer and viral diseases. However, transferred TCR chains can pair with endogenous TCR chains, resulting in the formation of mispaired TCR dimers and decreased or unspecific reactivity. TCR gene transfer into hematopoietic stem cells (HSCs) is an alternative to create T cells with desired Ag specificity, because in this case expression of endogenous TCR chains is then less likely owing to allelic exclusion. We generated TCR-transduced T cells from peripheral T cells using the lymphocytic choriomeningitis virus-specific P14 TCR. After transfer of the P14 TCR genes into HSCs and subsequent reconstitution of irradiated mice, TCR-engineered HSC-derived T cells were produced. We then compared the Ag-specific T cell populations with P14 TCR-transgenic T cells for their therapeutic efficiency in three in vivo models. In this study, we demonstrate that TCR-transduced T cells and TCR-engineered HSC-derived T cells are comparable in controlling lymphocytic choriomeningitis virus infection in mice and suppress growth of B16 tumor cells expressing the cognate Ag in a comparable manner.

Statins are a class of drugs that inhibit the rate-limiting step in the cholesterol biosynthetic pathway and show an anticancer effect, probably through the inhibition of cell proliferation. To date, the exact mechanism of cancer cell growth arrest induced by statins is not known. We report that simvastatin is able to induce apoptosis in melanoma cells but not in normal cells and also able to contrast the growth of tumor in an experimental melanoma murine model. We observed a delay in the tumor development in almost the 50% of the simvastatin administered animals and a strong reduction of the tumor volume with a differences of ~150% compared to the controls. Also the survival rate was significantly higher in mice that received the drug with a survival increase of ~130% compared to the controls. The tumor growth reduction in mice was supported by the results of cell migration assay, confirming that simvastatin clearly reduced cell migration. Moreover, simvastatin induced a strong downregulation of NonO gene expression, an important growth factor involved in the splicing regulation. This result could explain the decrease of melanoma cells proliferation, suggesting a possible action mechanism. The results derived from our experiments may sustain the many reports on the anticancer inhibitory property of statins and encourage new studies on this drug for a possible use in therapy, probably in combination with conventional chemotherapy.