Antitumor effects of the GM3(Neu5Gc) ganglioside-specific humanized antibody 14F7hT against Cmah-transfected cancer cells

Chimeric antigen receptor T cells targeting the GM3(Neu5Gc) ganglioside

Chimeric antigen receptor (CAR) T cell technology has ushered in a new era of immunotherapy, enabling the targeting of a broad range of surface antigens, surpassing the limitations of traditional T cell epitopes. Despite the wide range of non-protein tumor-associated antigens, the advancement in crafting CAR T cells for these targets has been limited. Owing to an evolutionary defect in the CMP-Neu5Ac hydroxylase (CMAH) that abolishes the synthesis of CMP-Neu5Gc from CMP-Neu5Ac, Neu5Gc is generally absent in human tissues. Despite this, Neu5Gc-containing antigens, including the ganglioside GM3(Neu5Gc) have consistently been observed on tumor cells across a variety of human malignancies. This restricted expression makes GM3(Neu5Gc) an appealing and highly specific target for immunotherapy. In this study, we designed and evaluated 14F7-28z CAR T cells, with a targeting unit derived from the GM3(Neu5Gc)-specific murine antibody 14F7. These cells exhibited exceptional specificity, proficiently targeting GM3(Neu5Gc)-expressing murine tumor cells in syngeneic mouse models, ranging from B cell malignancies to epithelial tumors, without compromising safety. Notably, human tumor cells enhanced with murine Cmah were effectively targeted and eliminated by the 14F7 CAR T cells. Nonetheless, despite the detectable presence of GM3(Neu5Gc) in unmodified human tumor xenografts, the levels were insufficient to trigger a tumoricidal T-cell response with the current CAR T cell configuration. Overall, our findings highlight the potential of targeting the GM3(Neu5Gc) ganglioside using CAR T cells across a variety of cancers and set the stage for the optimization of 14F7-based therapies for future human clinical application.

Detection of N-glycolyl-neuraminic acid-containing glycolipids in human skin

Humans lack the enzyme that produces the sialic acid N-glycolyl neuraminic acid (Neu5Gc), but several lines of evidence have shown that Neu5Gc can be taken up by mammalian food sources and replace the common human sialic acid N-acetyl neuraminic acid (Neu5Ac) in glycans. Cancer tissue has been shown to have increased the presence of Neu5Gc and Neu5Gc-containing glycolipids such as the ganglioside GM3, which have been proposed as tumor-specific antigens for antibody treatment. Here, we show that a previously described antibody against Neu5Gc-GM3 is binding to Neu5GC-containing gangliosides and is strongly staining different cancer tissues. However, we also found a strong intracellular staining of keratinocytes of healthy skin. We confirmed this staining on freshly isolated keratinocytes by flow cytometry and detected Neu5Gc by mass spectrometry. This finding implicates that non-human Neu5Gc can be incorporated into gangliosides in human skin, and this should be taken into consideration when targeting Neu5Gc-containing gangliosides for cancer immunotherapy.

Cancer-Associated Gangliosides as a Therapeutic Target for Host Defense Peptide Mimics

Aberrant levels of glycolipids expressed on cellular surfaces are characteristic of different types of cancers. The oligomer of acylated lysine (OAK) mimicking antimicrobial peptides displays in vitro activity against human and murine melanoma cell lines with upregulated GD3 and GM3 gangliosides. Herein, we demonstrate the capability of OAK to intercalate into the sialo-oligosaccharides of DPPC/GD3 and DPPC/GM3 lipid monolayers using X-ray scattering. The lack of insertion into monolayers containing phosphatidylserine suggests that the mechanism of action by OAKs against glycosylated lipid membranes is not merely driven by charge effects. The fluorescence microscopy data demonstrates the membrane-lytic activity of OAK. Understanding the molecular basis for selectivity toward GD3 and GM3 gangliosides by antimicrobial lipopeptides will contribute to the development of novel therapies to cure melanoma and other malignancies.

Pathophysiological roles and applications of glycosphingolipids in the diagnosis and treatment of cancer diseases

Glycosphingolipids (GSLs) are major amphiphilic glycolipids present on the surface of living cell membranes. They have important biological functions, including maintaining plasma membrane stability, regulating signal transduction, and mediating cell recognition and adhesion. Specific GSLs and related enzymes are abnormally expressed in many cancer diseases and affect the malignant characteristics of tumors. The regulatory roles of GSLs in signaling pathways suggest that they are involved in tumor pathogenesis. GSLs have therefore been widely studied as diagnostic markers of cancer diseases and important targets of immunotherapy. This review describes the tumor-related biological functions of GSLs and systematically introduces recent progress in using diverse GSLs and related enzymes to diagnose and treat tumor diseases. Development of drugs and biomarkers for personalized cancer therapy based on GSL structure is also discussed. These advances, combined with recent progress in the preparation of GSLs derivatives through synthetic biology technologies, suggest a strong future for the use of customized GSL libraries in treating human diseases.

N-glycolylneuraminic acid as a carbohydrate cancer biomarker

One of the forms of aberrant glycosylation in human tumors is the expression of N-glycolylneuraminic acid (Neu5Gc). The only known enzyme to biosynthesize Neu5Gc in mammals, cytidine-5'-monophosphate-N-acetylneuraminic acid (CMAH), appears to be genetically inactivated in humans. Regardless, low levels of Neu5Gc have been detected in healthy humans. Therefore, it is proposed that the presence of Neu5Gc in humans is from dietary acquisition, such as red meat. Notably, detection of elevated Neu5Gc levels has been repeatedly found in cancer tissues, cells and serum samples, thereby Neu5Gc-containing antigens may be exploited as a class of cancer biomarkers. Here we review the findings to date on using Neu5Gc-containing tumor glycoconjugates as a class of cancer biomarkers for cancer detection, surveillance, prognosis and therapeutic targets. We review the evidence that supports an emerging hypothesis of de novo Neu5Gc biosynthesis in human cancer cells as a source of Neu5Gc in human tumors, generated under certain metabolic conditions.

Mass Spectrometry-Based Glycoproteomic Workflows for Cancer Biomarker Discovery

Glycosylation has a clear role in cancer initiation and progression, with numerous studies identifying distinct glycan features or specific glycoproteoforms associated with cancer. Common findings include that aggressive cancers tend to have higher expression levels of enzymes that regulate glycosylation as well as glycoproteins with greater levels of complexity, increased branching, and enhanced chain length1. Research in cancer glycoproteomics over the last 50-plus years has mainly focused on technology development used to observe global changes in glycosylation. Efforts have also been made to connect glycans to their protein carriers as well as to delineate the role of these modifications in intracellular signaling and subsequent cell function. This review discusses currently available techniques utilizing mass spectrometry-based technologies used to study glycosylation and highlights areas for future advancement.

SILAC-based quantitative proteomics and microscopy analysis of cancer cells treated with the N-glycolyl GM3-specific anti-tumor antibody 14F7

Cancer immunotherapy represents a promising approach to specifically target and treat cancer. The most common mechanisms by which monoclonal antibodies kill cells include antibody-dependent cell-mediated cytotoxicity, complement-dependent cytotoxicity and apoptosis, but also other mechanisms have been described. 14F7 is an antibody raised against the tumor-associated antigen NeuGc GM3, which was previously reported to kill cancer cells without inducing apoptotic pathways. The antibody was reported to induce giant membrane lesions in tumor cells, with apparent changes in the cytoskeleton. Here, we investigated the effect of humanized 14F7 on HeLa cells using stable isotope labeling with amino acids in cell culture (SILAC) in combination with LC-MS and live cell imaging. 14F7 did not kill the HeLa cells, however, it caused altered protein expression (MS data are available via ProteomeXchange with identifier PXD024320). Several cytoskeletal and nucleic-acid binding proteins were found to be strongly down-regulated in response to antibody treatment, suggesting how 14F7 may induce membrane lesions in cells that contain higher amounts of NeuGc GM3. The altered expression profile identified in this study thus contributes to an improved understanding of the unusual killing mechanism of 14F7.

CAR T cells targeting the ganglioside NGcGM3 control ovarian tumors in the absence of toxicity against healthy tissues

Chimeric antigen receptor (CAR) T cells have emerged as a powerful immunotherapeutic tool against certain hematological malignancies but a significant proportion of patients either do not respond or they relapse, sometimes as a result of target antigen loss. Moreover, limited clinical benefit has been reported for CAR therapy against epithelial derived solid tumors. A major reason for this is the paucity of solid tumor antigens identified to date that are broadly, homogeneously and stably expressed but not found on healthy tissues. To address this, here we describe the development and evaluation of CAR T cells directed against N-glycoslylated ganglioside monosialic 3 (NGcGM3). NGcGM3 derives from the enzymatic hydroxylation of N-acetylneuraminic acid (NAc) GM3 (NAcGM3) and it is present on the surface of a range of cancers including ovarian, breast, melanoma and lymphoma. However, while NAcGM3 is found on healthy human cells, NGcGM3 is not due to the 7deletion of an exon in the gene encoding for the enzyme cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH). Indeed, unlike for most mammals, in humans NGcGM3 is considered a neoantigen as its presence on tumors is the result of metabolic incorporation from dietary sources. Here, we have generated 3 CARs comprising different single chain variable fragments (scFvs) originating from the well-characterized monoclonal antibody (mAb) 14F7. We show reactivity of the CAR T cells against a range of patient tumor fragments and we demonstrate control of NGcGM3⁺ SKOV3 ovarian tumors in the absence of toxicity despite the expression of CMAH and presence of NGcGM3⁺ on healthy tissues in NSG mice. Taken together, our data indicate clinical potential for 14F7-based CAR T cells against a range of cancers, both in terms of efficacy and of patient safety.

Synthetic O-Acetyl-N-glycolylneuraminic Acid Oligosaccharides Reveal Host-Associated Binding Patterns of Coronaviral Glycoproteins

A panel of O-acetylated N-glycolylneuraminic acid oligosaccharides has been prepared by diversification of common synthetic precursors by regioselective de-O-acetylation by coronaviral hemagglutinin-esterase (HE) combined with C7-to-C9 acetyl ester migration. The resulting compound library was printed on streptavidin-coated glass slides to give a microarray to investigate receptor binding specificities of viral envelope glycoproteins, including spike proteins and HEs from animal and human coronaviruses. It was found that the binding patterns of the viral proteins for N-glycolylated sialosides differ considerable from those of the previously synthesized N-acetylated counterparts. Generally, the spike proteins tolerate N-glycolyl modification, but selectivities differ among viruses targeting different hosts. On the other hand, the lectin domain of the corresponding HEs showed a substantial decrease or loss of binding of N-glycolylated sialosides. MD simulations indicate that glycolyl recognition by HE is mediated by polar residues in a loop region (109-119) that interacts with the 5-N-glycolyl moiety. Collectively, the results indicate that coronaviruses have adjusted their receptor fine specificities to adapt to the sialoglycome of their host species.

The Effect of Hypoxia and Hypoxia-Associated Pathways in the Regulation of Antitumor Response: Friends or Foes?

Hypoxia is an environmental stressor that is instigated by low oxygen availability. It fuels the progression of solid tumors by driving tumor plasticity, heterogeneity, stemness and genomic instability. Hypoxia metabolically reprograms the tumor microenvironment (TME), adding insult to injury to the acidic, nutrient deprived and poorly vascularized conditions that act to dampen immune cell function. Through its impact on key cancer hallmarks and by creating a physical barrier conducive to tumor survival, hypoxia modulates tumor cell escape from the mounted immune response. The tumor cell-immune cell crosstalk in the context of a hypoxic TME tips the balance towards a cold and immunosuppressed microenvironment that is resistant to immune checkpoint inhibitors (ICI). Nonetheless, evidence is emerging that could make hypoxia an asset for improving response to ICI. Tackling the tumor immune contexture has taken on an in silico, digitalized approach with an increasing number of studies applying bioinformatics to deconvolute the cellular and non-cellular elements of the TME. Such approaches have additionally been combined with signature-based proxies of hypoxia to further dissect the turbulent hypoxia-immune relationship. In this review we will be highlighting the mechanisms by which hypoxia impacts immune cell functions and how that could translate to predicting response to immunotherapy in an era of machine learning and computational biology.

Targeting Tumor Glycans for Cancer Therapy: Successes, Limitations, and Perspectives

Simple Summary

Aberrant glycosylation is a common feature of many cancers, and it plays crucial roles in tumor development and biology. Cancer progression can be regulated by several physiopathological processes controlled by glycosylation, such as cell–cell adhesion, cell–matrix interaction, epithelial-to-mesenchymal transition, tumor proliferation, invasion, and metastasis. Different mechanisms of aberrant glycosylation lead to the formation of tumor-associated carbohydrate antigens (TACAs), which are suitable for selective cancer targeting, as well as novel antitumor immunotherapy approaches. This review summarizes the strategies developed in cancer immunotherapy targeting TACAs, analyzing molecular and cellular mechanisms and state-of-the-art methods in clinical oncology.

Abstract

Aberrant glycosylation is a hallmark of cancer and can lead to changes that influence tumor behavior. Glycans can serve as a source of novel clinical biomarker developments, providing a set of specific targets for therapeutic intervention. Different mechanisms of aberrant glycosylation lead to the formation of tumor-associated carbohydrate antigens (TACAs) suitable for selective cancer-targeting therapy. The best characterized TACAs are truncated O-glycans (Tn, TF, and sialyl-Tn antigens), gangliosides (GD2, GD3, GM2, GM3, fucosyl-GM1), globo-serie glycans (Globo-H, SSEA-3, SSEA-4), Lewis antigens, and polysialic acid. In this review, we analyze strategies for cancer immunotherapy targeting TACAs, including different antibody developments, the production of vaccines, and the generation of CAR-T cells. Some approaches have been approved for clinical use, such as anti-GD2 antibodies. Moreover, in terms of the antitumor mechanisms against different TACAs, we show results of selected clinical trials, considering the horizons that have opened up as a result of recent developments in technologies used for cancer control.

Cancer glycomics offers potential biomarkers and therapeutic targets in the framework of 3P medicine

Glycosylation is one of the most important post-translational modifications (PTMs) in a protein, and is the most abundant and diverse biopolymer in nature. Glycans are involved in multiple biological processes of cancer initiation and progression, including cell-cell interactions, cell-extracellular matrix interactions, tumor invasion and metastasis, tumor angiogenesis, and immune regulation. As an important biomarker, tumor-associated glycosylation changes have been extensively studied. This article reviews recent advances in glycosylation-based biomarker research, which is useful for cancer diagnosis and prognostic assessment. Truncated O-glycans, sialylation, fucosylation, and complex branched structures have been found to be the most common structural patterns in malignant tumors. In recent years, immunochemical methods, lectin recognition-based methods, mass spectrometry (MS)-related methods, and fluorescence imaging-based in situ methods have greatly promoted the discovery and application potentials of glycomic and glycoprotein biomarkers in various cancers. In particular, MS-based proteomics has significantly facilitated the comprehensive research of extracellular glycoproteins, increasing our understanding of their critical roles in regulating cellular activities. Predictive, preventive and personalized medicine (PPPM; 3P medicine) is an effective approach of early prediction, prevention and personalized treatment for different patients, and it is known as the new direction of medical development in the 21st century and represents the ultimate goal and highest stage of medical development. Glycosylation has been revealed to have new diagnostic, prognostic, and even therapeutic potentials. The purpose of glycosylation analysis and utilization of biology is to make a fundamental change in health care and medical practice, so as to lead medical research and practice into a new era of 3P medicine.

Key role of a structural water molecule for the specificity of 14F7-An antitumor antibody targeting the NeuGc GM3 ganglioside

Tumor-associated glycolipids such as NeuGc GM3 are auspicious molecular targets in antineoplastic therapies and vaccine strategies. 14F7 is a monoclonal IgG1 with high clinical potential in cancer immunotherapy as it displays extraordinary specificity for NeuGc GM3, while it does not recognize the very similar, ubiquitous NeuAc GM3. Here we present the 2.3 Å crystal structure of the 14F7 antigen-binding domain (14F7 scFv) in complex with the NeuGc GM3 trisaccharide. Modeling analysis and previous mutagenesis data suggest that 14F7 may also bind to an alternative NeuGc GM3 conformation, not observed in the crystal structure. The most intriguing finding, however, was that a water molecule centrally placed in the complementarity-determining region directly mediates the specificity of 14F7 to NeuGc GM3. This has profound impact on the complexity of engineering in the binding site and provides an excellent example of the importance in understanding the water structure in antibody-antigen interactions.

The Distinct Roles of Sialyltransferases in Cancer Biology and Onco-Immunology

Aberrant glycosylation is a key feature of malignant transformation. Hypersialylation, the enhanced expression of sialic acid-terminated glycoconjugates on the cell surface, has been linked to immune evasion and metastatic spread, eventually by interaction with sialoglycan-binding lectins, including Siglecs and selectins. The biosynthesis of tumor-associated sialoglycans involves sialyltransferases, which are differentially expressed in cancer cells. In this review article, we provide an overview of the twenty human sialyltransferases and their roles in cancer biology and immunity. A better understanding of the individual contribution of select sialyltransferases to the tumor sialome may lead to more personalized strategies for the treatment of cancer.

Site-Selective Acylations of α- and β-Hydroxyamides in Complex Molecules: Application of Template-Driven Acylation to Disaccharides and a Glycopeptide

Site-selective acylations of α-and β-hydroxyamides in complex polyols are described. The combination of a pyridine aldoxime ester and Zn(OTf)₂ facilitates the acylation of two types of N-glycolyl disaccharides, namely, Gal-GlcNGc and Neu5Gc-Gal, both of which are partial structures of polysaccharides responsible for biological actions, with highly site-selective modifications achieved. Furthermore, biotinylation, one of the most important techniques in chemical biology, is used to site-selectively acylate the β-hydroxyl group in a glycopeptide.

Phenylboronic acid conjugated to doxorubicin nanocomplexes as an anti-cancer drug delivery system in hepatocellular carcinoma

Anti-cancer strategies using nanocarrier systems have been explored in a variety of cancers; these systems can easily be incorporated into tumors via the enhanced permeability and retention (EPR) effect leading to enhanced anti-tumor activity while reducing systemic toxicity by specific tumor-targeting. The prognosis of hepatocellular carcinoma (HCC) is extremely poor when the condition is diagnosed at the unresectable stage as treatment options are limited. In order to improve the treatment of cancer and the overall anti-cancer effect, polymerized phenylboronic acid conjugated doxorubicin (pPBA-Dox) nanocomplexes were generated, and conjugated doxorubicin, which is conventionally used in HCC. The nanocomplexes exhibited enhanced anti-tumor activity via tumor-specific targeting in the subcutaneous and orthotopic HCC syngeneic mice tumor model, implying that the nanocomplexes facilitate the targeted Dox delivery to liver cancer in which the sialic acid is over-expressed. Therefore, this study provides insight into the novel targeted therapy using the nanocomplexes for the treatment of HCC.

Targeting glyco-immune checkpoints for cancer therapy

Introduction: Targeting immune checkpoints with antibodies has significantly improved the outcome of cancer patients, but only few patients have long-term benefits from currently used PD-1/PD-L1 and CTLA-4 inhibitors. New approaches are needed to increase the number of patients going into long-term remission after cancer immunotherapy. Glyco-immune checkpoints are new targets for cancer immunotherapy. They are defined as immune-modulatory pathways including interactions of glycans with glycan-binding proteins or lectins. The most prominent pathway is the sialoglycan-Siglec axis and inhibitors of this axis are already successfully tested in early clinical trials.Area covered: Here, we summarize the current knowledge on glyco-immune checkpoints with a focus on the sialoglycan-Siglec axis. We also provide an overview on current approaches to clinically target glyco-immune checkpoints and give an outlook for the further clinical development of glyco-immune checkpoint targeting agents.Expert opinion: Glyco-immune checkpoints are interesting new targets to improve cancer immunotherapy. Antibodies targeting the sialoglycan-Siglec axis are already in clinical development. Other approaches with higher risk of toxicity including tumor-targeted sialidases are in late stage pre-clinical development. Despite the challenges, targeting of glyco-immune checkpoints could lead to the development of a new class of drugs providing improved anti-cancer immunity and eventually benefit cancer patients.

Prognostic Significance of Tumor Tissue NeuGcGM3 Ganglioside Expression in Patients Receiving Racotumomab Immunotherapy

Expression of N-glycolyl GM3 (NeuGcGM3) ganglioside was detected in the tumor specimens of patients who were on Racotumomab anti-idiotype vaccine maintenance treatment, and prognostic significance as a biomarker was investigated. No statistically significant association was observed in the multivariate analysis between overall survival and tissue NeuGcGM3 IHC levels. Although numerically there was a difference favoring less intense IHC for better prognosis, this did not reach statistical power. However, there was a strong correlation between Racotumomab doses and overall survival (OS). Mean OS of the patient with more than 10 Racotumomab application was significantly longer than the patient who had less than 10 injections (70.7 months vs. 31.1 months, p < 0.001). We propose that, regardless of staining intensity, the presence of NeuGcGM3 in patient tissues might be an indicator of benefit in Racotumomab treatment.

Xenogeneic Neu5Gc and self-glycan Neu5Ac epitopes are potential immune targets in MS

OBJECTIVE

To explore the repertoire of glycan-specific immunoglobulin G (IgG) antibodies in treatment-naive patients with relapsing-remitting multiple sclerosis (RRMS).

METHODS

A systems-level approach combined with glycan array technologies was used to determine specificities and binding reactivities of glycan-specific IgGs in treatment-naive patients with RRMS compared with patients with noninflammatory and other inflammatory neurologic diseases.

RESULTS

We identified a unique signature of glycan-binding IgG in MS with high reactivities to the dietary xenoglycan N-glycolylneuraminic acid (Neu5Gc) and the self-glycan N-acetylneuraminic acid (Neu5Ac). Increased reactivities of serum IgG toward Neu5Gc and Neu5Ac were additionally observed in an independent, treatment-naive cohort of patients with RRMS.

CONCLUSION

Patients with MS show increased IgG reactivities to structurally related xenogeneic and human neuraminic acids. The discovery of these glycan-specific epitopes as immune targets and potential biomarkers in MS merits further investigation.