Adjuvant For Cancer Immunotherapy Research Articles

Small molecule inhibitors as adjuvants in cancer immunotherapy: enhancing efficacy and overcoming resistance.

Adjuvant therapy is essential in cancer treatment to enhance primary treatment effectiveness, reduce adverse effects, and prevent recurrence. Small molecule inhibitors as adjuvants in cancer immunotherapy aim to harness their immunomodulatory properties to optimize treatment outcomes. By modulating the tumor microenvironment, enhancing immune cell function, and increasing tumor sensitivity to immunotherapy, small molecule inhibitors have the potential to improve patient responses. This review discusses the evolving use of small molecule inhibitors as adjuvants in cancer treatment, highlighting their role in enhancing the efficacy of immunotherapy and the opportunities for advancing cancer therapies in the future.

Manganese@Albumin Nanocomplex and Its Assembled Nanowire Activate TLR4-Dependent Signaling Cascades of Macrophages.

The immunomodulatory effect of divalent manganese cations (Mn2+ ), such as activation of the cGAS-STING pathway or NLRP3 inflammasomes, positions them as adjuvants for cancer immunotherapy. In this study, it is found that trace Mn2+ ions, bound to bovine serum albumin (BSA) to form Mn@BSA nanocomplexes, stimulate pro-inflammatory responses in human- or murine-derived macrophages through TLR4-mediated signaling cascades. Building on this, the assembly of Mn@BSA nanocomplexes to obtain nanowire structures enables stronger and longer-lasting immunostimulation of macrophages by regulating phagocytosis. Furthermore, Mn@BSA nanocomplexes and their nanowires efficiently activate peritoneal macrophages, reprogramme tumor-associated macrophages, and inhibit the growth of melanoma tumors in vivo. They also show better biosafety for potential clinical applications compared to typical TLR4 agonists such as lipopolysaccharides. Accordingly, the findings provide insights into the mechanism of metalloalbumin complexes as potential TLR agonists that activate macrophage polarization and highlight the importance of their nanostructures in regulating macrophage-mediated innate immunity.

Plant Viruses as Adjuvants for Next-Generation Vaccines and Immunotherapy.

Vaccines are the cornerstone of infectious disease control and prevention. The outbreak of SARS-CoV-2 has confirmed the urgent need for a new approach to the design of novel vaccines. Plant viruses and their derivatives are being used increasingly for the development of new medical and biotechnological applications, and this is reflected in a number of preclinical and clinical studies. Plant viruses have a unique combination of features (biosafety, low reactogenicity, inexpensiveness and ease of production, etc.), which determine their potential. This review presents the latest data on the use of plant viruses with different types of symmetry as vaccine components and adjuvants in cancer immunotherapy. The discussion concludes that the most promising approaches might be those that use structurally modified plant viruses (spherical particles) obtained from the Tobacco mosaic virus. These particles combine high adsorption properties (as a carrier) with strong immunogenicity, as has been confirmed using various antigens in animal models. According to current research, it is evident that plant viruses have great potential for application in the development of vaccines and in cancer immunotherapy.

Hydroxyapatite Biobased Materials for Treatment and Diagnosis of Cancer.

Great advances in cancer treatment have been undertaken in the last years as a consequence of the development of new antitumoral drugs able to target cancer cells with decreasing side effects and a better understanding of the behavior of neoplastic cells during invasion and metastasis. Specifically, drug delivery systems (DDS) based on the use of hydroxyapatite nanoparticles (HAp NPs) are gaining attention and merit a comprehensive review focused on their potential applications. These are derived from the intrinsic properties of HAp (e.g., biocompatibility and biodegradability), together with the easy functionalization and easy control of porosity, crystallinity and morphology of HAp NPs. The capacity to tailor the properties of DLS based on HAp NPs has well-recognized advantages for the control of both drug loading and release. Furthermore, the functionalization of NPs allows a targeted uptake in tumoral cells while their rapid elimination by the reticuloendothelial system (RES) can be avoided. Advances in HAp NPs involve not only their use as drug nanocarriers but also their employment as nanosystems for magnetic hyperthermia therapy, gene delivery systems, adjuvants for cancer immunotherapy and nanoparticles for cell imaging.

Antitumor effect of Escherichia coli-derived outer membrane vesicles on neuroblastoma in vitro and in vivo.

Bacterial outer membrane vesicles (OMVs) are spherical microbubbles that contain biological content and are produced by gram-negative bacteria. The use of OMVs as adjuvants for cancer immunotherapy or as drug carriers for targeted therapies has attracted the interest of many scholars. However, it is unclear whether OMVs can exert direct antitumor effects and whether OMVs can inhibit pediatric tumors. Here, we explore the potential of Escherichia coli-derived OMVs to directly suppress neuroblastoma. Our results demonstrate the antitumor effects of OMVs in vitro and in vivo, and no serious adverse reactions were observed. OMV uptake into the cytoplasm and nucleus directly decreases cell stemness, DNA damage, apoptosis and cell cycle arrest, which may be the mechanisms by which OMVs suppress tumors. Our results demonstrate the potential of bacterial OMVs to be used as antitumor adjuvant therapies, increasing the number of candidates for the development of cancer therapies in the future. More relevant studies are urgently needed to demonstrate the efficacy and safety of OMVs.

Abstract 4215: Combination of STING and TLR 7/8 agonists as vaccine adjuvants for cancer immunotherapy

Abstract Various classes of molecules including toll-like receptor (TLR) agonists, exosomes, and metallo compounds have been evaluated as adjuvants for cancer vaccines. However, their wide-spread clinical use has been limited by transient immune responses and serious side-effects. Here, we propose the use of a multi-adjuvant approach that combines two different classes of adjuvants, STING and TLR 7/8 agonists, based on their distinct immune cell targets, signalling pathways, and significant roles in the activation and maintenance of immune responses. We evaluated the potential of combining 522, a novel TLR 7/8 agonist, and DMXAA, a STING agonist, for stronger DC activation and greater CD8 T cell responses. Mouse bearing B16F10-OVA (murine melanoma cell line which expresses ovalbumin) tumors were immunized with OVA mixed with 522 or DMXAA or a combination of 522 and DMXAA daily for 5 days. Immunization with OVA+DMXAA+522 resulted in significant tumor growth inhibition (p < 0.05) and improved survival (p<0.05) compared to other controls. Using flow cytometry, the costimulatory molecule expression and immune cell infiltration in mouse lymph node, spleen and tumor were evaluated. Immunization with OVA+DMXAA+522 resulted in the activation of antigen presenting cells (APCs) in lymph nodes, spleen and tumor (additive or equivalent to single treated groups). The combination also elicited stronger antigen specific CD8 T cell and natural killer (NK) cell responses than control or individual treatment groups. OVA + DMXAA+ 522 immunization increased the number of OVA-specific CD44high CD8 T cells by over 4-fold compared to other treatment groups and control mice in spleen and lymph nodes. A reduction in the frequency of M2 macrophages was observed with OVA+DMXAA+522 treatment. Cytokine analysis demonstrated higher levels of pro-inflammatory cytokines like IFNγ and lower levels of pro-tumorigenic cytokines in the serum of OVA+DMXAA+522 immunized mice compared to that in untreated or OVA-only treated mice. Taken together, these results suggest that combination of TLR7/8 and STING agonists is a promising multi-adjuvant approach for cancer vaccination Citation Format: Shubhmita Bhatnagar, Vishnu Revuri, Manan Shah, Peter Larson, David Ferguson, Jayanth Panyam. Combination of STING and TLR 7/8 agonists as vaccine adjuvants for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4215.

Multifaceted glycoadjuvant@AuNPs inhibits tumor metastasis through promoting T cell activation and remodeling tumor microenvironment

AbstarctBackgroundCytosine-phosphate-guanine (CpG) dinucleotides has been used as adjuvants for cancer immunotherapy. However, unmodified CpG are not very efficient in clinical trials. Glucose, ligand of C-type lectin receptors (CLRs), can promote DC maturation and antigen presentation, which is the first step of induction of adaptive immune responses. Therefore, conjugation of type B CpG DNA to glucose-containing glycopolymers may enhance the therapeutic effects against tumor by CpG-based vaccine.MethodsgCpG was developed by chemical conjugation of type B CpG DNA to glucose-containing glycopolymers. The therapeutic effects of gCpG-based vaccine were tested in both murine primary melanoma model and its metastasis model.ResultsgCpG based tumor vaccine inhibited both primary and metastasis of melanoma in mice which was dependent on CD8 + T cells and IFNγ. In tumor microenvironment, gCpG treatment increased Th1 and CTL infiltration, increased M1 macrophages, decreased Tregs and MDSCs populations, and promoted inflammatory milieu with enhanced secretion of IFNγ and TNFα. The anti-tumor efficacy of gCpG was dramatically enhanced when combined with anti-PD1 immunotherapy.ConclusionsWe confirmed that gCpG was a promising adjuvant for vaccine formulation by activating both tumor-specific Th1 and Tc1 responses, and regulating tumor microenvironments.Graphical

Reduction-Sensitive Protein Nanogels Enhance Uptake of Model and Tumor Lysate Antigens In Vitro by Mouse- and Human-Derived Dendritic Cells.

Peptides and proteins represent an emerging class of powerful therapeutics. Peptide and protein nanogels are attractive carriers for the transport and delivery of biologically active peptides and proteins because they allow essentially quantitative encapsulation of these biologics. One interesting field of use of peptide and protein nanogels is the transport of antigens and adjuvants in cancer immunotherapy. This study demonstrates the use of reduction-sensitive protein nanogels for the delivery of ovalbumin and oxidized tumor lysate-based antigens to mouse and human-donor-derived dendritic cells. Challenging mouse-derived and human dendritic cells with reduction-sensitive ovalbumin nanogels was found to significantly enhance antigen uptake as compared to the use of the corresponding free protein antigen. The experiments with mouse-derived dendritic cells further showed that the administration of ovalbumin in the form of reduction-sensitive nanogels enhanced dendritic cell maturation as well as the presentation of the SIINFEKL epitope as compared to experiments that use free ovalbumin. In addition to ovalbumin as a model antigen, the feasibility of reduction-sensitive nanogels was also demonstrated for the delivery of oxidized, whole tumor lysate-based cancer antigens. In experiments with dendritic cells harvested from human donors, dendritic cell uptake of the oxidized tumor lysate antigen was significantly enhanced in experiments that used oxidized tumor lysate nanogels as compared to the free antigen.

LN Monocytes Limit DC-Poly I:C Induced Cytotoxic T Cell Response via IL-10 and Induction of Suppressor CD4 T Cells.

Every immune response has accelerators and brakes. Depending on the pathogen or injury, monocytes can play either role, promoting or resolving immunity. Poly I:C, a potent TLR3 ligand, licenses cross-presenting dendritic cells (DC1) to accelerate a robust cytotoxic T cells response against a foreign antigen. Poly I:C thus has promise as an adjuvant in cancer immunotherapy and viral subunit vaccines. Like DC1s, monocytes are also abundant in the LNs. They may act as either immune accelerators or brakes, depending on the inflammatory mediator they encounter. However, little is known about their contribution to adaptive immunity in the context of antigen and Poly I:C. Using monocyte-deficient and chimeric mice, we demonstrate that LN monocytes indirectly dampen a Poly I:C induced antigen-specific cytotoxic T cell response, exerting a “braking” function. This effect is mediated by IL-10 production and induction of suppressor CD4+ T cells. In a metastatic melanoma model, we show that a triple-combination prophylactic treatment consisting of anti-IL-10, tumor peptides and Poly I:C works because removing IL-10 counteracts the monocytic brake, resulting in significantly fewer tumors compared to mice treated with tumor peptides and Poly I:C alone. Finally, in human LN tissue, we observed that monocytes (unlike DCs) express high levels of IL-10, suggesting that anti-IL-10 may be an important addition to treatments. Overall, our data demonstrates that LN monocytes regulate the induction of a robust DC1-mediated immune response. Neutralization of either IL-10 or monocytes can augment Poly I:C-based treatments and enhance T cell cytotoxicity.

Metabolites Profiling of Melanoma Interstitial Fluids Reveals Uridine Diphosphate as Potent Immune Modulator Capable of Limiting Tumor Growth.

Tumor interstitial fluid (TIF) surrounds and perfuses tumors and collects ions, metabolites, proteins, and extracellular vesicles secreted by tumor and stromal cells. Specific metabolites, accumulated within the TIF, could induce metabolic alterations of immune cells and shape the tumor microenvironment. We deployed a metabolomic approach to analyze the composition of melanoma TIF and compared it to the plasma of C57BL6 mice, engrafted or not with B16-melanoma cells. Among the classes of metabolites analyzed, monophosphate and diphosphate nucleotides resulted enriched in TIF compared to plasma samples. The analysis of the effects exerted by guanosine diphosphate (GDP) and uridine diphosphate (UDP) on immune response revealed that GDP and UDP increased the percentage of CD4+CD25+FoxP3– and, on isolated CD4+ T-cells, induced the phosphorylation of ERK, STAT1, and STAT3; increased the activity of NF-κB subunits p65, p50, RelB, and p52; increased the expression of Th1/Th17 markers including IFNγ, IL17, T-bet, and RORγt; and reduced the expression of IL13, a Th2 marker. Finally, we observed that local administrations of UDP in B16-engrafted C57BL6 mice reduced tumor growth and necrotic areas. In addition, UDP-treated tumors showed a higher presence of MHCIIhi tumor-associated macrophage (TAM) and of CD3+CD8+ and CD3+CD4+ tumor-infiltrating T-lymphocytes (TILs), both markers of anti-tumor immune response. Consistent with this, intra-tumoral gene expression analysis revealed in UDP-treated tumors an increase in the expression of genes functionally linked to anti-tumor immune response. Our analysis revealed an important metabolite acting as mediator of immune response, which could potentially represent an additional tool to be used as an adjuvant in cancer immunotherapy.

Clickable amino acid derivative tuned self-assembly of antigen and adjuvant for cancer immunotherapy

Amino acid-tuned self-assembly has become an attractive strategy for constructing various functional materials. Here, a series of dibenzocyclooctyne (DIBO) functionalized amphiphilic amino acid derivatives are designed and screened as building blocks of functional supramolecular self-assembly nanoparticles for cancer immunotherapy. One top-performing supramolecular self-assembly material (named DA6C1) is identified through combinatorial screening, and spherical nanoparticles can be easily prepared by this material tuned multicomponent synergistic self-assembly of ovalbumin (OVA) and CpG oligonucleotide. DA6C1 based nanovaccine can significantly enhance the cellular uptake of OVA and CpG into the same bone marrow derived dendritic cells (BMDCs) and greatly improve the activation of DCs. Moreover, after subcutaneous injection, this nanovaccine flows rapidly to the lymph nodes and elicits strong immune responses to achieve effective prophylactic and therapeutic effect. Therefore, our work highlights the great potential of clickable amino acid derivatives as a convenient and powerful tool to construct nanovaccine for effective immunotherapy.

Activation of stimulator of interferon genes in dendritic cells induces interferon-lambda and subset- and species-specific dendritic cell death

Abstract Stimulator of Interferon (IFN) Genes (STING), a cytosolic DNA sensor that recognises cyclic dinucleotides (CDNs), has been an adjuvant target in many cancer immunotherapies. Activation of STING results in the production of Type I IFN through the phosphorylation of TANK-binding kinase 1 (TBK1) and IFN regulatory factor 3 (IRF3) and it is thought this enhances cross-presentation of tumour antigens by dendritic cells (DCs). However, DCs interrogated in many of these studies use in vitro-generated DCs instead of putative ex vivo DCs, and the direct effects of STING activation on different DC subsets are not completely understood. Here, we report that mouse and humanised mouse splenic DC subsets as well as human blood DCs are activated by CDN stimulation and produce Type III IFN (IFN-lambda) but only type 2 conventional DCs (cDC2s) and plasmacytoid DCs (pDCs) produce Type I IFN in response to CDN stimulation. However, only mouse pDCs aberrantly express extremely high levels of CD86 and CD80 and are ablated rapidly after STING activation. Some DC death was also observed in mouse and human cDC2s, but not in human pDCs. This ablation is STING-dependent and occurs via a cell-intrinsic mechanism involving intrinsic apoptosis. These observations demonstrate the differential effects STING activation has on DC subsets as well as highlight a discordance amongst mouse and human DCs during activation, which serve as an important consideration in the translation of animal cancer models and the use of STING ligands as adjuvants in cancer immunotherapy.

Biocompatible ionic liquids assisted transdermal co-delivery of antigenic protein and adjuvant for cancer immunotherapy

Human skin contains numerous antigen-presenting cells that are a potential target for several immune-based therapies, including vaccination and cancer immunotherapy. However, the outermost layer of the skin—the stratum corneum—acts as a major physical barrier against the permeation of antigens that have a molecular weight > 500 Da. In this study, an ionic liquid-assisted delivery system (ILDS) was developed, which enabled the successful transdermal delivery of an antigenic protein, ovalbumin (OVA), with a toll-like receptor agonist, imiquimod, as an adjuvant, to stimulate a specific immune response. Both the ionic liquids and ILDS were completely biocompatible for topical or transdermal application for therapeutic purposes. The skin permeation of the antigenic protein and adjuvant was found to be significantly enhanced because of the incorporation of a surface-active ionic liquid in the ILDS. An in vivo immunization study showed that there was a high level of OVA-specific IgG antibody production because of the enhanced permeation of the antigen and adjuvant across and into the skin. In a preclusive anticancer study, vaccination through ILDS showed stronger tumor-growth inhibition compared to control group. These results indicated that the ILDS could be a promising strategy for transdermal immunization as future therapeutics.

Oxidized curdlan activates dendritic cells and enhances antitumor immunity

Curdlan activates dendritic cells (DCs) and enhances DC-based antitumor immunity. However, hydrophobicity and heterogeneity of curdlan particulates hinder perfect binding of curdlan to dectin-1 receptor, resulting in the reduced activation of antigen presenting cells and limited antitumor effects. Herein, we synthesized partially oxidized curdlan derivative (β-1,3-polyglucuronic acid, denote PGA). PGA-45 polymer, the reaction product prepared from curdlan by oxidation with 4-acetamido-TEMPO/NaClO/NaClO2 systems under acid conditions for 45 min, activated DCs, induced the expression of co-stimulatory molecules and cytokines, and promoted allogenic T cell proliferation as well as the expression of IL-2. Mechanistically, PGA-45 polymer strongly enhanced phosphorylation of IKK-β and reduced the expression of phosphorylated Akt, suggesting that PGA-45 may activate multiple cell surface receptors such as TLR4 and dectin-1. Administration of tumor lysate pulsed DCs pre-treated with PGA-45 particles induced strong antitumor activity in B16F10 melanoma model. Our data suggest that PGA-45 have strong adjuvant effects for anti-cancer immunity and the design of PGA polymers may provide insights in the development of novel adjuvants for cancer immunotherapy.

Abstract PO024: Differential binding of E. coli enterotoxins LT-IIa, LT-IIb and LT-IIc to human B and T cell subsets identifies a potential use as adjuvants in cancer immunotherapy

Abstract There is an urgent need for development of new adjuvants to target and drive immune responses in cancer immunotherapies. The E. coli type-II heat-labile enterotoxins (HLEs) LT-IIa, LT-IIb and LT-IIc exhibit strong adjuvant properties with varying capacities to elicit immune responses in mice. The immunomodulatory capabilities of these HLEs depend upon their interactions with specific ganglioside receptors that may vary in expression across immune cell types. Little is known, however, about the lymphoid cells that interact with HLEs in humans. To bridge this gap, human normal PBMCs, isolated by Ficoll density gradient centrifugation, were stained with recombinant B subunits of LT-IIa, LT-IIb, or LT-IIc, and mAbs to CD4, CD8, CD19, CD27, CD38 and CD45RO. Using FACS analysis, we found that LT-IIa, LT-IIb and LT-IIc increasingly bound to CD4+ T cells as the cells transitioned from naive (CD4+CD45RO-CD27+) to memory (CD4+CD45RO+CD27+) cells and from memory cells to effector memory (CD4+CD45RO+CD27-) cells, with LT-IIb exhibiting the most significant increase in binding. Likewise, LT-IIb and LT-IIc increasingly bound to CD8+ T cells as the cells transitioned from naive (CD8+CD45RO-CD27+) to memory (CD8+CD45RO+CD27+) cells and from memory cells to effector memory (CD8+CD45RO+CD27-) cells, with the greatest increase observed for LT-IIb. No major changes in LT-IIa binding were detected during CD8+ T cell differentiation. Finally, LT-IIa and LT-IIc increasingly bound to CD19+ B cells as the cells transitioned from naive (CD19+CD27-) to memory (CD19+CD27+) cells and from memory cells to antibody-secreting (CD19+/-CD27++CD38++) plasma cells, with LT-IIa exhibiting the most significantly increased binding activity. No major changes in LT-IIb binding were observed during B cell differentiation. Taken together, these results suggest that the ganglioside receptors for HLEs (e.g., GD1a, GD1b and GM1) are differentially expressed throughout B and T cell development/differentiation and that binding of HLEs to the various lymphocyte subsets is likely to elicit distinct cellular events associated with immune modulation or immune responsiveness. Understanding of these HLE binding patterns may also prove useful in targeting additional immunomodulating drugs to specific T or B cell subpopulations. Ultimately, characterization of immunological responses to these enterotoxins will lead to a greater understanding of their potential use in targeted cancer immunotherapies for treatment of a wide variety of conditions. Citation Format: Mary-Peyton A. Knapp, Taylor A. Johnson, Madison K. Ritter, Robert O. Rainer, Steven E. Fiester, Jennifer T. Grier, Terry D. Connell, Sergio Arce. Differential binding of E. coli enterotoxins LT-IIa, LT-IIb and LT-IIc to human B and T cell subsets identifies a potential use as adjuvants in cancer immunotherapy [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO024.

Soluble and Exosome-Bound α-Galactosylceramide Mediate Preferential Proliferation of Educated NK Cells with Increased Anti-Tumor Capacity.

Simple SummaryMany cancers down-regulate the expression of major histocompatibility complex class I (MHC-I) to avoid recognition and elimination by the adaptive immune system. Natural Killer (NK) cells, as part of innate immunity, complement tumor recognition by their ability to sense foreign and malignant cells by the lack of major MHC-I expression. During development, NK cells learn to perceive physiological levels of self MHC-I as healthy in a process termed NK cell education. In the current study, we assessed whether the stimulation of natural killer T (NKT) cells could impact the tumor-killing ability of NK cells. We can show that stimulation with a well-established activator of NKT cells induces the preferential expansion of educated NK cells, and improves NK-cell-mediated tumor-killing of both MHC-I+ and MHC-I− tumor cells. Furthermore, this increased tumor-killing capacity of NK cells can be achieved by nanovesicle-mediated delivery, which is known to improve adaptive immunity as well. Our approach thus holds great potential for future cancer immunotherapy.Natural killer (NK) cells can kill target cells via the recognition of stress molecules and down-regulation of major histocompatibility complex class I (MHC-I). Some NK cells are educated to recognize and kill cells that have lost their MHC-I expression, e.g., tumor or virus-infected cells. A desired property of cancer immunotherapy is, therefore, to activate educated NK cells during anti-tumor responses in vivo. We here analyze NK cell responses to α-galactosylceramide (αGC), a potent activator of invariant NKT (iNKT) cells, or to exosomes loaded with αGC. In mouse strains which express different MHC-I alleles using an extended NK cell flow cytometry panel, we show that αGC induces a biased NK cell proliferation of educated NK cells. Importantly, iNKT cell-induced activation of NK cells selectively increased in vivo missing self-responses, leading to more effective rejection of tumor cells. Exosomes from antigen-presenting cells are attractive anti-cancer therapy tools as they may induce both innate and adaptive immune responses, thereby addressing the hurdle of tumor heterogeneity. Adding αGC to antigen-loaded dendritic-cell-derived exosomes also led to an increase in missing self-responses in addition to boosted T and B cell responses. This study manifests αGC as an attractive adjuvant in cancer immunotherapy, as it increases the functional capacity of educated NK cells and enhances the innate, missing self-based antitumor response.

Escherichia coli adhesion portion FimH functions as an adjuvant for cancer immunotherapy

Induction of antigen-specific immune activation by the maturation of dendritic cells (DCs) is a strategy used for cancer immunotherapy. In this study, we find that FimH, which is an Escherichia coli adhesion portion, induces toll-like receptor 4-dependent and myeloid differentiation protein 2-independent DC maturation in mice in vivo. A combined treatment regimen with FimH and antigen promotes antigen-specific immune activation, including proliferation of T cells, production of IFN-γ and TNF-α, and infiltration of effector T cells into tumors, which consequently inhibits tumor growth in mice in vivo against melanoma and carcinoma. In addition, combined therapeutic treatment of anti-PD-L1 antibodies and FimH treatment efficiently inhibits CT26 tumor growth in BALB/c mice. Finally, FimH promotes human peripheral blood DC activation and syngeneic T-cell proliferation and activation. Taken together, these findings demonstrate that FimH can be a useful adjuvant for cancer immunotherapy.

Methylselenol producing selenocompounds enhance the efficiency of mammaglobin-A peptide vaccination against breast cancer cells.

Previous phase I DNA-vaccine based clinical trials using Mammaglobin-A (Mam-A), a human breast tumor associated antigen (TAA), demonstrated that this agent was safe and efficient at treating patients with stage IV breast cancer. The long-term success of cancer vaccines is limited by the diminished expression of human leukocyte antigen (HLA) class I molecules in the tumor microenvironment. The current study assessed the impact of various selenocompounds on the expression of HLA class I molecules in THP-1 cells, an apparent proficient antigen that presents a human monocyte-like cell line, and their eventual activation of MamA2.1 (HLA-A2 immunodominant epitope of Mam-A) specific cytotoxic CD8+ T lymphocytes (CTLs). The results revealed that, following treatment with methylselenol producing compounds [methylselenic acid (MSA) and dimethylselenide (DMDSe)], the expression of HLA class-I was increased and components involved with the antigen presentation machinery of THP-1 cells were upregulated. Furthermore, CTLs activated by MamA2.1 peptide presenting THP-1 cells, pre-treated with MSA and DMDSe, demonstrated an enhanced cytotoxicity in HLA-A2+/Mam-A+ AU565 and UACC-812 breast cancer cell lines when compared with CTLs activated by THP-1 cells without drug treatment. However, no significant cytotoxicity was observed under similar conditions in HLA-A2+/Mam-A- MCF-7 and MDA-MB-231 breast cancer cell lines. The results indicated that treatment with methylselenol producing compounds retained antigen-dependent activation of CD8+ T cells. The data of the current study demonstrated that MSA and DMDSe potentiated effector cytotoxic responses following TAA specific activation of CTLs, indicating their future role as vaccine adjuvants in cancer immunotherapy.

Abstract 576: A novel intestinal microbiome-derived peptide modulates host T cell activation

Abstract The microbiome shapes the metabolic and immunological landscape of individuals in health and disease and represents a new robust source of bioactive molecules with therapeutic potential. Second Genome’s large and curated microbiome database coupled with its proprietary bioinformatics and machine learning pipeline enables the discovery of novel microbiome-derived drug candidates across multiple disease areas, including immuno-oncology (IO). Microbial genus Bifidobacterium previously showed a positive association with antitumor T cell responses in mouse models and was overrepresented in melanoma patients responding to immunotherapy with anti-PD-1 antibody. Our hypothesis is that bioactive molecules derived from these Bifidobacteria help drive these antitumor responses and could function as cancer therapeutics or adjuvants for cancer immunotherapy. Thus, we nominated protein and peptide candidates with high scores of secretability, uniqueness, stability, and expressability from Bifidobacterium breve and Bifidobacterium longum genomes for screening in cell-based assays. Initial evaluation of more than 50 Bifidobacterium peptides revealed candidates capable of inducing immune activation. Here, we describe a B. breve-derived peptide (termed SG-B) that induced up-regulation of co-stimulatory (OX40 and ICOS) and inhibitory (PD-1) molecules on CD4+ and CD8+ T cells in both: i) a purified human pan-T cell system; and ii) PBMC cultures stimulated with low-dose anti-CD3 antibody. Furthermore, SG-B stimulated secretion of effector cytokines by in vitro-cultured purified T cells (TNF-a, IL-2, IFN-g, and IL-10) and PBMCs (IL-1b, IL-6, and IL-8). These effects were dose-dependent and evident across multiple human blood donors. In the CT26 syngeneic tumor model, peri-tumoral administration of SG-B induced an increase in the proportion of NK cells and CD4+ T cells within the tumor. The peptide also induced up-regulation of activation marker on CD8+ T cells (CD25, Ki67, and OX40). Collectively, these data suggest that SG-B can modulate adaptive immunity via T cell potentiation and may enhance tumor inflammation in vivo. The peptide’s ability to up-regulate key co-stimulatory and checkpoint molecules on T cells provides a strong rationale for its potential future use in combination with approved or IO agents in current development. These results validate the capability of the Second Genome drug discovery platform to identify novel microbial agents of potential therapeutic relevance in IO and demonstrate a unique approach that can identify microbial factors involved in modulating immune cell effector functions and/or immune cell differentiation. Citation Format: Yuliya V. Katlinskaya, Dhwani Haria, Lily McLaughlin, Sunit Jain, Shoko Iwai, Todd DeSantis, Thomas Weinmaier, Toshi Takeuchi, Anu Hoey, Karim Dabbagh, Kareem Graham, Helena Kiefel. A novel intestinal microbiome-derived peptide modulates host T cell activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 576.

Selenocompounds mediated upregulation of HLA class I expression enhanced mammaglobin-A peptide-specific cytotoxic T lymphocyte responses against breast cancer cells

Abstract Recent phase I DNA vaccine clinical trials with Mammaglobin-A (Mam-A), a human breast tumor-associated antigen (TAA), have shown to be safe and efficient. However, the success of cancer vaccines is limited by the diminished expression of HLA class I molecules on cancer cells. In our current communication, we studied the impact of various selenocompounds towards the expression of HLA class I molecules on breast cancer cells and their impact on the cytotoxicity of MamA2.1 (HLA-A2 immunodominant epitope of Mam-A) activated human CD8+T lymphocytes (hCTLs). We noted an enhanced HLA-A2 expression along with upregulation of components involved in antigen presentation machinery in all four breast cancer cell lines, namely AU565, UACC-812, MCF-7, and MDA-MB-231, following treatment with methyselenol producing methylseninic acid (MSA) and dimethylselenide (DMDSe). Furthermore, we have demonstrated enhanced cytotoxicity of MamA2.1 activated CTLs on HLA-A2+/Mam-A+ AU565 and UACC-812 cell lines following pre-treatment with MSA and DMDSe, while no significant toxicity was noted under similar conditions on HLA-A2+/Mam-A− MCF-7 and MDA-MB-231 breast cancer cell lines. Taken together, our data demonstrated that MSA and DMDSe potentiate effector cytotoxic responses following TAA vaccine specific activation of CD8+T lymphocytes, and thus suggesting their futuristic role as vaccine adjuvants in cancer immunotherapy.