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BackgroundTreatments that generate T cell-mediated immunity to a patient’s unique neoantigens are the current holy grail of cancer immunotherapy. In particular, treatments that do not require cumbersome and individualized ex vivo processing or manufacturing processes are especially sought after. Here we report that AGI-134, a glycolipid-like small molecule, can be used for coating tumor cells with the xenoantigen Galα1-3Galβ1-4GlcNAc (α-Gal) in situ leading to opsonization with pre-existing natural anti-α-Gal antibodies (in short anti-Gal), which triggers immune cascades resulting in T cell mediated anti-tumor immunity.MethodsVarious immunological effects of coating tumor cells with α-Gal via AGI-134 in vitro were measured by flow cytometry: (1) opsonization with anti-Gal and complement, (2) antibody-dependent cell-mediated cytotoxicity (ADCC) by NK cells, and (3) phagocytosis and antigen cross-presentation by antigen presenting cells (APCs). A viability kit was used to test AGI-134 mediated complement dependent cytotoxicity (CDC) in cancer cells. The anti-tumoral activity of AGI-134 alone or in combination with an anti-programmed death-1 (anti-PD-1) antibody was tested in melanoma models in anti-Gal expressing galactosyltransferase knockout (α1,3GT−/−) mice. CDC and phagocytosis data were analyzed by one-way ANOVA, ADCC results by paired t-test, distal tumor growth by Mantel–Cox test, C5a data by Mann–Whitney test, and single tumor regression by repeated measures analysis.ResultsIn vitro, α-Gal labelling of tumor cells via AGI-134 incorporation into the cell membrane leads to anti-Gal binding and complement activation. Through the effects of complement and ADCC, tumor cells are lysed and tumor antigen uptake by APCs increased. Antigen associated with lysed cells is cross-presented by CD8α+ dendritic cells leading to activation of antigen-specific CD8+ T cells. In B16-F10 or JB/RH melanoma models in α1,3GT−/−mice, intratumoral AGI-134 administration leads to primary tumor regression and has a robust abscopal effect, i.e., it protects from the development of distal, uninjected lesions. Combinations of AGI-134 and anti-PD-1 antibody shows a synergistic benefit in protection from secondary tumor growth.ConclusionsWe have identified AGI-134 as an immunotherapeutic drug candidate, which could be an excellent combination partner for anti-PD-1 therapy, by facilitating tumor antigen processing and increasing the repertoire of tumor-specific T cells prior to anti-PD-1 treatment.

The cholinergic anti-inflammatory pathway can directly affect skin antibacterial responses via nicotinic acetylcholine receptors (nAChRs). In particular, α7 nAChR (CHRNA7) present in the epidermis modulates the host response to wounding and/or wound bacterial infection. While physiologic inflammation is required to initiate normal wound repair and can be triggered by Toll-like receptor (TLR) activation, chronic inflammation is frequently observed in diabetic wounds and can occur, in part, via excessive TLR2 activation or production. Consequently, this can delay physiologic wound healing responses and increase diabetic host susceptibility to bacterial infection. In this study, we demonstrate that topical nAChR activation diminishes bacterial survival and systemic dissemination in a mouse model of diabetic wound infection, while reducing wound TLR2 production, relative to control mice. We further determined that the antimicrobial peptide activity of diabetic mouse wounds is increased compared to control mice, but this effect is lost following topical nAChR activation. Finally, we observed that human diabetic wounds exhibit impaired α7 nAChR (CHRNA7) abundance and localization relative to human control (nondiabetic) skin. These findings suggest that topical administration of nAChR agonists may improve wound healing and infection outcomes in diabetic wounds by dampening TLR2-mediated inflammation and antimicrobial peptide response, and that the diabetic microenvironment may promote aberrant CHRNA7 production/activation that likely contributes to diabetic wound pathogenesis.

The ever-increasing threat of multi-drug resistant bacterial infections has spurred renewed interest in alternative approaches to classical antibiotic therapy. In contrast to other mammals, humans do not express the galactose-α-1,3-galactosyl-β-1,4-N-acetyl-glucosamine (α-Gal) epitope. As a result of exposure of humans to α-Gal in the environment, a large proportion of circulating antibodies are specific for the trisaccharide. In this study, we examine whether these anti-Gal antibodies can be recruited and redirected to exert anti-bacterial activity. We show that a specific DNA aptamer conjugated to an α-Gal epitope at its 5′ end, herein termed an alphamer, can bind to group A Streptococcus (GAS) bacteria by recognition of a conserved region of the surface-anchored M protein. The anti-GAS alphamer was shown to recruit anti-Gal antibodies to the streptococcal surface in an α-Gal-specific manner, elicit uptake and killing of the bacteria by human phagocytes, and slow growth of invasive GAS in human whole blood. These studies provide a first in vitro proof of concept that alphamers have the potential to redirect pre-existing antibodies to bacteria in a specific manner and trigger an immediate antibacterial immune response. Further validation of this novel therapeutic approach of applying α-Gal technology in in vivo models of bacterial infection is warranted. • α-Gal-tagged aptamers lead to GAS opsonization with anti-Gal antibodies. • α-Gal-tagged aptamers confer phagocytosis and killing of GAS cells by human phagocytes. • α-Gal-tagged aptamers reduces replication of GAS in human blood. • α-Gal-tagged aptamers may have the potential to be used as novel passive immunization drugs.

A proof-of-concept study evaluating the potential of Streptococcus pneumoniae Pneumococcal Surface Protein A (PspA) as a passive immunization target was conducted. We describe the generation and isolation of several broadly reactive mouse anti-PspA monoclonal antibodies (mAbs). MAb 140H1 displayed (i) 98% strain coverage, (ii) activity in complement deposition and opsonophagocytic killing (OPK) assays, which are thought to predict the in vivo efficacy of anti-pneumococcal mAbs, (iii) efficacy in mouse sepsis models both alone and in combination with standard-of-care antibiotics, and (iv) therapeutic activity in a mouse pneumonia model. Moreover, we demonstrate that antibody engineering can significantly enhance anti-PspA mAb effector function. We believe that PspA has promising potential as a target for the therapy of invasive pneumococcal disease by mAbs, which could be used alone or in conjunction with standard-of-care antibiotics.

68 Background: AGI-134 is a fully synthetic alpha-Gal glycolipid for intratumoral (i.t.) treatment of solid tumors to induce a patient-specific anti-tumor immune response. AGI-134 recruits pre-existing anti-Gal antibodies to the injected lesion, leading to complement activation and enhanced tumor antigen processing. Using the B16.F10 murine melanoma model, we have previously demonstrated that AGI-134 evokes a robust abscopal anti-tumor effect, with treatment of a primary lesion protecting mice from the growth of distant lesions. In the current study, we investigated the response of injected tumors to AGI-134 administration. Methods: Tumors were induced by s.c. injection of B16.F10 or ovalbumin expressing B16 (B16.OVA) cells into the flank of α1,3galactosyltransferase knock out mice. After reaching a treatable size, the tumors were injected twice, 24 hrs apart, with PBS or 1-1.25 mg AGI-134, and tumor growth monitored for up to 32 days. In addition, to measure the activation of complement after treatment with AGI-134, tumors were processed 2 hours after treatment and the i.t. concentration of complement fragment C5a determined by ELISA. Results: Almost 50% of AGI-134-treated B16.F10 tumors fully regressed vs. 24% in the PBS controls. Moreover, AGI-134 treatment had a significant survival benefit, with 23% of AGI-134-treated mice dying or requiring euthanisia due to tumor mass by Day 27 post treatment vs. 43% in the PBS groups (p < 0.05, Mantel-Cox test). In the B16.OVA model, 67% of the AGI-134 treated tumors fully regressed vs. 0% in PBS-treated mice in two independent assays. Comparison of C5a levels in B16.F10 tumors 2 hrs after AGI-134 or PBS treatment demonstrated that AGI-134 induced significant complement activation within injected tumors. Conclusions: Having previously shown that AGI-134 induces an abscopal effect that protects mice from the development of secondary tumors, we now show that AGI-134 also induces regression of injected tumors: AGI-134-treatment induces the activation of complement within the tumor and leads to complete regression of the tumor in significantly more AGI-134-treated mice than PBS-treated. Clinical trials with AGI-134 are planned for 2018.

BlaI is a repressor of BlaZ, the beta-lactamase responsible for penicillin resistance in Staphylococcus aureus. Through screening a transposon library in S. aureus Newman for susceptibility to cathelicidin antimicrobial peptide, we discovered BlaI as a novel cathelicidin resistance factor. Additionally, through integrational mutagenesis in S. aureus Newman and MRSA Sanger 252 strains, we confirmed the role of BlaI in resistance to human and murine cathelidicin and showed that it contributes to virulence in human whole blood and murine infection models. We further demonstrated that BlaI could be a target for innate immune-based antimicrobial therapies; by removing BlaI through subinhibitory concentrations of 6-aminopenicillanic acid, we were able to sensitize S. aureus to LL-37 killing.

Background: AGI-134 is a fully synthetic α-Gal (Galα1-3Galβ1-4GlcNAc-R) glycolipid that is being developed for the treatment of solid tumors. The α-Gal epitope is not expressed in humans, who, as a result of constant antigenic stimulation by α-Gal-bearing commensal bacteria, develop high titer natural antibodies to α-Gal. We have previously demonstrated that AGI-134 recruits anti-Gal antibodies to tumor cells in vitro, activating complement and driving phagocytosis by antigen presenting cells. AGI-134 also confers systemic protection from distal lesion development in a mouse model of melanoma and synergizes with anti-PD-11. Here we present further data characterizing the multiple pathways activated by the anti-Gal subclasses to drive AGI-134-mediated anti-tumor immunity. Results: Using quantitative methods, we demonstrate that human anti-Gal is composed of a diverse repertoire of effector antibodies in a panel of serum samples, with IgM, IgG1 and IgG2 being the major subclasses. Polyclonal anti-Gal IgG purified from human IVIG was, like human serum, comprised mainly of IgG1 and IgG2. When AGI-134 treated cells were incubated with human serum, binding of all anti-Gal subclasses was detected by flow cytometry, demonstrating that all anti-Gal subclasses can interact with AGI-134 treated cells and are available to activate downstream effector functions. When human serum was depleted of IgG, AGI-134 stimulated complement dependent cytotoxicity (CDC) was still effective, indicating that anti-Gal IgM is primarily responsible for deposition of complement on AGI-134 treated cells. AGI-134 treated cells incubated with purified polyclonal anti-Gal IgG activated FcγRIIIA on a reporter cell line and promoted natural killer cell-mediated antibody-dependent cell-mediated cytotoxicity (ADCC). Opsonization of AGI-134 treated human cancer cells with human anti-Gal and complement stimulated their phagocytosis by human monocyte-derived macrophages. Ovalbumin-expressing cells treated with AGI-134 and then incubated with human serum to initiate CDC were specifically phagocytosed by murine CD8α+ dendritic cells and the immunodominant antigen of ovalbumin, SIINFEKL, was cross-presented to CD8+ T cells. In conclusion, AGI-134 stimulates adaptive anti-tumor immunity through immune activation and antigen cross-presentation, which is driven by the diverse repertoire of anti-Gal antibodies. 1. Shaw, S. et al. Abstract 4862: AGI-134: a fully synthetic alpha-Gal glycolipid that prevents the development of distal lesions and is synergistic with an anti-PD-1 antibody in a mouse melanoma model. [abstract]. AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4862. Citation Format: Jenny L. Middleton, Oliver Schulz, Amber Charlemagne, Sascha A. Kristian, Stephen Michael Shaw. The novel α-Gal-based immunotherapy AGI-134 invokes CD8+ T cell-mediated immunity by driving tumor cell destruction, phagocytosis and tumor-associated antigen cross-presentation via multiple antibody-mediated effector functions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 616. doi:10.1158/1538-7445.AM2017-616

Background: AGI-134 is a fully synthetic glycolipid, composed of an alpha-Gal (Galá1-3Galâ1-4GlcNAc-R) sugar epitope attached via a linker to a lipid tail. Natural antibodies to the alpha-Gal epitope are responsible for the hyperacute rejection of xenografts in humans. It is proposed that intratumorally administered AGI-134 will incorporate into the cell membranes of the tumor cells, presenting the alpha-Gal epitope for binding of anti-Gal antibodies to the tumor cells. This will initiate an immune response that attacks the injected tumor and, through uptake of immune-complexed tumor antigens by antigen presenting cells, will create a patient-specific, systemic anti-tumor response against distant metastases. Results: We demonstrate that AGI-134 incorporates into tumor cell membranes in vitro and that the exposed alpha-Gal epitope binds anti-Gal IgG and IgM antibodies from human serum to the tumor cell surface. Using flow cytometry and a complement-dependent cytotoxicity assay we show that tumor cell opsonization with anti-Gal antibodies leads to deposition of complement proteins C3b and C5b-9, which ultimately leads to tumor cell lysis. Furthermore, we demonstrate that AGI-134-labeled tumor cells opsonized with human serum proteins are phagocytosed by professional APCs. Using the B16-F10 melanoma model in anti-Gal producing á1,3-galactosyltransferase knockout (GT KO) mice we present data to demonstrate that AGI-134 injection into a primary tumor provides significant dose-dependent protection from the development of established distant lesions. Using GT KO mouse serum we demonstrate in vitro that deposition of complement on AGI-134-labeled mouse tumor cells is both alpha-Gal and anti-Gal dependent. In vivo, we demonstrate that the effect of AGI-134 is due to the alpha-Gal moiety by replacing it with human blood group antigens. The protection from secondary lesions conferred by AGI-134 is long lasting in the GT KO mouse melanoma model (monitored up to 90 days). Importantly, when sub-optimal concentrations of AGI-134 were tested in vivo in combination with an anti-PD-1 antibody (RMP1-14), a significant enhancement in efficacy over either of the agents administered alone was observed. Citation Format: Stephen Shaw, Sascha Kristian, Kim Wigglesworth, Jenny Middleton, Mel Glossop, Giles Whalen, Robert Old, Mike Westby, Chris Pickford. AGI-134: a fully synthetic alpha-Gal glycolipid that prevents the development of distal lesions and is synergistic with an anti-PD-1 antibody in a mouse melanoma model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4862.

3083Background: Unlike virtually all non-primate mammals, humans lack α-Gal (Gal-α-1,3-Gal-β-1,4-GlcNAc) epitopes and produce antibodies against α-Gal-positive antigens. Anti-α-Gal (anti-Gal) antibodies are among the most abundant antibodies in humans and responsible for hyper-acute rejection of α-Gal-positive xenotransplants. Studies using rabbit-derived α-Gal glycolipids provided a preclinical proof of principle for α-Gal glycolipids as cancer immunotherapy, inducing a CD8+ T cell response to tumor associated antigens (TAAs) that correlated with protection from distal tumor growth in mice. In the current study we show that a fully synthetic, α-Gal glycolipid-like small molecule, AGI-134, displays potent anti-tumor activity by engaging the cellular and humoral immune system against TAAs. Methods: in vitro and in vivo studies. Results: AGI-134 inserts into the plasma membranes of mouse and human cancer cells in vitro. Anti-Gal IgM and IgG bind to the α-Gal labeled cancer cells and mediate an anti-cancer c...