The development of synthetic antitumour vaccines from mucin glycopeptide antigens

Highly stereoselective α-glycosylation with GalN3 donors enabled collective synthesis of mucin-related tumor associated carbohydrate antigens

Mucin-related tumor-associated carbohydrate antigens (TACAs) are important and interesting targets for cancer vaccine therapy. However, efficient access to a library of mucin-related TACAs remains a challenging task. One of the key issues is the challenging construction of α-GalNAc linkages. Here, we report highly stereoselective α-glycosylation with GalN3N-phenyl trifluoroacetimidate donors, which features excellent yields, outstanding stereoselectivities, broad substrate scope and mild reaction conditions. This method is successfully applied to highly stereoselective synthesis of GalN3-α-O-Ser, which served as the common intermediate for collective synthesis of a wide range of TACAs including TN antigen, STN antigen, 2,6 STF antigen, 2,3 STF antigen, glycophorin and cores 1-8 mucin-type O-glycans. In particular, the rationale for this highly stereoselective α-glycosylation is provided for the first time using DFT calculations and mechanistic studies, highlighting the crucial roles of reagent combinations (TMSI and Ph3PO) and the H-bonding directing effect of the N3 group.

Immunomodulatory Peptides for Tumor Treatment

Peptides exhibit various biological activities, including biorecognition, cell targeting, and tumor penetration, and can stimulate immune cells to elicit immune responses for tumor immunotherapy. Peptide self-assemblies and peptide-functionalized nanocarriers can reduce the effect of various biological barriers and the degradation by peptidases, enhancing the efficiency of peptide delivery and improving antitumor immune responses. To date, the design and development of peptides with various functionalities have been extensively reviewed for enhanced chemotherapy; however, peptide-mediated tumor immunotherapy using peptides acting on different immune cells, to the knowledge, has not yet been summarized. Thus, this work provides a review of this emerging subject of research, focusing on immunomodulatory anticancer peptides. This review introduces the role of peptides in the immunomodulation of innate and adaptive immune cells, followed by a link between peptides in the innate and adaptive immune systems. The peptides are discussed in detail, following a classification according to their effects on different innate and adaptive immune cells, as well as immune checkpoints. Subsequently, two delivery strategies for peptides as drugs are presented: peptide self-assemblies and peptide-functionalized nanocarriers. The concluding remarks regarding the challenges and potential solutions of peptides for tumor immunotherapy are presented.

Efficient Production of Self-Assembled Bioconjugate Nanovaccines against Klebsiella pneumoniae O2 Serotype in Engineered Escherichia coli

Nanoparticles (NPs) have been surfacing as a pivotal platform for vaccine development. In our previous work, we developed a cholera toxin B subunit (CTB)-based self-assembled nanoparticle (CNP) and produced highly promising bioconjugate nanovaccines by loading bacterial polysaccharide (OPS) in vivo. In particular, the Klebsiella pneumoniae O2 serotype vaccine showcased a potent immune response and protection against infection. However, extremely low yields limited its further application. In this study, we prepared an efficient Klebsiella pneumoniae bioconjugate nanovaccine in Escherichia coli with a very high yield. By modifying the 33rd glycine (G) in the CNP to aspartate (D), we were able to observe a dramatically increased expression of glycoprotein. Subsequently, through a series of mutations, we determined that G33D was essential to increasing production. In addition, this increase only occurred in engineered E. coli but not in the natural host K. pneumoniae strain 355 (Kp355) expressing OPSKpO2. Next, T-cell epitopes were fused at the end of the CNP(G33D), and animal experiments showed that fusion of the M51 peptide induced high antibody titers, consistent with the levels of the original nanovaccine, CNP-OPSKpO2. Hence, we provide an effective approach for the high-yield production of K. pneumoniae bioconjugate nanovaccines and guidance for uncovering glycosylation mechanisms and refining glycosylation systems.

Advances in Therapeutic Cancer Vaccines, Their Obstacles, and Prospects Toward Tumor Immunotherapy

Over the past few decades, cancer immunotherapy has experienced a significant revolution due to the advancements in immune checkpoint inhibitors (ICIs) and adoptive cell therapies (ACTs), along with their regulatory approvals. In recent times, there has been hope in the effectiveness of cancer vaccines for therapy as they have been able to stimulate de novo T-cell reactions against tumor antigens. These tumor antigens include both tumor-associated antigen (TAA) and tumor-specific antigen (TSA). Nevertheless, the constant quest to fully achieve these abilities persists. Therefore, this review offers a broad perspective on the existing status of cancer immunizations. Cancer vaccine design has been revolutionized due to the advancements made in antigen selection, the development of antigen delivery systems, and a deeper understanding of the strategic intricacies involved in effective antigen presentation. In addition, this review addresses the present condition of clinical tests and deliberates on their approaches, with a particular emphasis on the immunogenicity specific to tumors and the evaluation of effectiveness against tumors. Nevertheless, the ongoing clinical endeavors to create cancer vaccines have failed to produce remarkable clinical results as a result of substantial obstacles, such as the suppression of the tumor immune microenvironment, the identification of suitable candidates, the assessment of immune responses, and the acceleration of vaccine production. Hence, there are possibilities for the industry to overcome challenges and enhance patient results in the coming years. This can be achieved by recognizing the intricate nature of clinical issues and continuously working toward surpassing existing limitations.

Lymph Node Targeting Mediated by Albumin Hitchhiking of Synthetic Tn Glycolipid Leads to Robust In Vivo Antibody Production

Tn antigen is a tumor-associated carbohydrate antigen, which is present prominently on the tumor cell surfaces and attracts an interest in vaccine development. This work demonstrates that a synthetic Tn antigen carrying glycoconjugate forms a complex with circulating albumin, delivers the antigen to lymph nodes (LNs), and leads to the efficient production of antibodies against the antigen. Synthetic Tn antigen glycoconjugate, possessing DSPE-PEG2000 linker and lipophilic moieties, undergoes micellization in PBS buffer. In the presence of bovine serum albumin (BSA), demicellization of the glycolipid occurs, with a rate constant of 0.18 min-1. In vitro studies show that the glycoconjugate binds preferentially to BSA in the presence of cells. Immunological assessments in mice models reveal the albumin-enabled delivery of the Tn glycoconjugate to antigen-presenting cells in the LNs, specifically leading to a robust humoral immune response. ELISA titers show superior binding, with a saturation dilution of 1:51 200 for Tn glycoconjugate, in comparison to that mediated by the Tn-BSA covalent conjugate with a saturation dilution of 1:6400. Immunohistochemical staining shows delivery of Tn glycoconjugate at the LNs, specifically at the subcapsular sinus and interfollicular areas. The work highlights the potential of albumin-mediated target delivery strategy for cancer immunotherapies.

Structure-Guided Approach for the Development of MUC1-Glycopeptide-Based Cancer Vaccines with Predictable Responses

Mucin-1 (MUC1) glycopeptides are exceptional candidates for potential cancer vaccines. However, their autoantigenic nature often results in a weak immune response. To overcome this drawback, we carefully engineered synthetic antigens with precise chemical modifications. To be effective and stimulate an anti-MUC1 response, artificial antigens must mimic the conformational dynamics of natural antigens in solution and have an equivalent or higher binding affinity to anti-MUC1 antibodies than their natural counterparts. As a proof of concept, we have developed a glycopeptide that contains noncanonical amino acid (2S,3R)-3-hydroxynorvaline. The unnatural antigen fulfills these two properties and effectively mimics the threonine-derived antigen. On the one hand, conformational analysis in water shows that this surrogate explores a landscape similar to that of the natural variant. On the other hand, the presence of an additional methylene group in the side chain of this analog compared to the threonine residue enhances a CH/π interaction in the antigen/antibody complex. Despite an enthalpy-entropy balance, this synthetic glycopeptide has a binding affinity slightly higher than that of its natural counterpart. When conjugated with gold nanoparticles, the vaccine candidate stimulates the formation of specific anti-MUC1 IgG antibodies in mice and shows efficacy comparable to that of the natural derivative. The antibodies also exhibit cross-reactivity to selectively target, for example, human breast cancer cells. This investigation relied on numerous analytical (e.g., NMR spectroscopy and X-ray crystallography) and biophysical techniques and molecular dynamics simulations to characterize the antigen-antibody interactions. This workflow streamlines the synthetic process, saves time, and reduces the need for extensive, animal-intensive immunization procedures. These advances underscore the promise of structure-based rational design in the advance of cancer vaccine development.

The future of cancer immunotherapy: DNA vaccines leading the way

Immuno-oncology has revolutionized cancer treatment and has opened up new opportunities for developing vaccination methods. DNA-based cancer vaccines have emerged as a promising approach to activating the bodily immune system against cancer. Plasmid DNA immunizations have shown a favorable safety profile and there occurs induction of generalized as well as tailored immune responses in preclinical and early-phase clinical experiments. However, these vaccines have notable limitations in immunogenicity and heterogeneity and these require refinements. DNA vaccine technology has been focusing on improving vaccine efficacy and delivery, with parallel developments in nanoparticle-based delivery systems and gene-editing technologies such as CRISPR/Cas9. This approach has showcased great promise in enhancing and tailoring the immune response to vaccination. Strategies to enhance the efficacy of DNA vaccines include the selection of appropriate antigens, optimizing insertion in a plasmid, and studying combinations of vaccines with conventional strategies and targeted therapies. Combination therapies have attenuated immunosuppressive activities in the tumor microenvironment and enhanced the capability of immune cells. This review provides an overview of the current framework of DNA vaccines in oncology and focuses on novel strategies, including established combination therapies and those still under development.The challenges that oncologists, scientists, and researchers need to overcome to establish DNA vaccines as an avant-garde approach to defeating cancer, are also emphasized. The clinical implications of the immunotherapeutic approaches and the need for predictive biomarkers have also been reviewed upon. We have also tried to extend the role of Neutrophil extracellular traps (NETs) to the DNA vaccines. The clinical implications of the immunotherapeutic approaches have also been reviewed upon. Ultimately, refining and optimizing DNA vaccines will enable harnessing the immune system's natural ability to recognize and eliminate cancer cells, leading the world towards a revolution in cancer cure.

Developing Next-Generation Protein-Based Vaccines Using High-Affinity Glycan Ligand-Decorated Glyconanoparticles

Major diseases, such as cancer and COVID-19, are frightening global health problems, and sustained action is necessary to develop vaccines. Here, for the first time, ethoxy acetalated dextran nanoparticles (Ace-Dex-NPs) are functionalized with 9-N-(4H-thieno[3,2-c]chromene-2-carbamoyl)-Siaα2-3Galβ1-4GlcNAc (TCC Sia-LacNAc) targeting macrophages as a universal vaccine design platform. First, azide-containing oxidized Ace-Dex-NPs are synthesized. After the NPs are conjugated with ovalbumin (OVA) and resiquimod (Rd), they are coupled to TCC Sia-LacNAc-DBCO to produce TCC Sia-Ace-Dex-OVA-Rd, which induce a potent, long-lasting OVA-specific cytotoxic T-lymphocyte (CTL) response and high anti-OVA IgG, providing mice with superior protection against tumors. Next, this strategy is exploited to develop vaccines against infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The receptor-binding domain (RBD) of the SARS-CoV-2 spike protein is the main target for neutralizing antibodies. The TCC Sia-Ace-Dex platform is preferentially used for designing an RBD-based vaccine. Strikingly, the synthetic TCC Sia-Ace-Dex-RBD-Rd elicited potent RBD-neutralizing antibodies against live SARS-CoV-2 infected Vero E6 cells. To develop a universal SARS-CoV-2 vaccine, the TCC Sia-Ace-Dex-N-Rd vaccine carrying SARS-CoV-2 nucleocapsid protein (N) is also prepared, which is highly conserved among SARS-CoV-2 and its variants of concern (VOCs), including Omicron (BA.1 to BA.5); this vaccine can trigger strong N-specific CTL responses against target cells infected with SARS-CoV-2 and its VOCs.

Preparation and applications of artificial mucins in biomedicine

Mucus is an essential barrier material that separates organisms from the outside world. This slippery material regulates the transport of nutrients, drugs, gases, and pathogens toward the cell surface. The surface of the cell itself is coated in a mucus-like barrier of glycoproteins and glycolipids. Mucin glycoproteins are the primary component of mucus and the epithelial glycocalyx. Aberrant mucin production is implicated in diverse disease states from cancer and inflammation to pre-term birth and infection. Biological mucins are inherently heterogenous in structure, which has challenged understanding their molecular functions as a barrier and as biochemically active proteins. Therefore, many synthetic materials have been developed as artificial mucins with precisely tunable structures. This review highlights advances in design and synthesis of artificial mucins and their application in biomedical studies of mucin chemistry, biology, and physics.

Research progress of the engagement of inorganic nanomaterials in cancer immunotherapy

Cancer has attracted widespread attention from scientists for its high morbidity and mortality, posing great threats to people’s health. Cancer immunotherapy with high specificity, low toxicity as well as triggering systemic anti-tumor response has gradually become common in clinical cancer treatment. However, due to the insufficient immunogenicity of tumor antigens peptides, weak ability to precisely target tumor sites, and the formation of tumor immunosuppressive microenvironment, the efficacy of immunotherapy is often limited. In recent years, the emergence of inorganic nanomaterials makes it possible for overcoming the limitations mentioned above. With self-adjuvant properties, high targeting ability, and good biocompatibility, the inorganic nanomaterials have been integrated with cancer immunotherapy and significantly improved the therapeutic effects.

Synthesis and biomedical applications of mucin mimic materials

Mucin glycoproteins are the major component of mucus and coat epithelial cell surfaces forming the glycocalyx. The glycocalyx and mucus are involved in the transport of nutrients, drugs, gases, and pathogens toward the cell surface. Mucins are also involved in diverse diseases such as cystic fibrosis and cancer. Due to inherent heterogeneity in native mucin structure, many synthetic materials have been designed to probe mucin chemistry, biology, and physics. Such materials include various glycopolymers, low molecular weight glycopeptides, glycopolypeptides, polysaccharides, and polysaccharide-protein conjugates. This review highlights advances in the area of design and synthesis of mucin mimic materials, and their biomedical applications in glycan binding, epithelial models of infection, therapeutic delivery, vaccine formulation, and beyond.

Aptamer-Based Probes for Cancer Diagnostics and Treatment

Aptamers are single-stranded DNA or RNA oligomers that have the ability to generate unique and diverse tertiary structures that bind to cognate molecules with high specificity. In recent years, aptamer researches have witnessed a huge surge, owing to its unique properties, such as high specificity and binding affinity, low immunogenicity and toxicity, and simplicity of synthesis with negligible batch-to-batch variation. Aptamers may bind to targets, such as various cancer biomarkers, making them applicable for a wide range of cancer diagnosis and treatment. In cancer diagnostic applications, aptamers are used as molecular probes instead of antibodies. They have the potential to detect various cancer-associated biomarkers. For cancer therapeutic purposes, aptamers can serve as therapeutic or delivery agents. The chemical stabilization and modification strategies for aptamers may expand their serum half-life and shelf life. However, aptamer-based probes for cancer diagnosis and therapy still face several challenges for successful clinical translation. A deeper understanding of nucleic acid chemistry, tissue distribution, and pharmacokinetics is required in the development of aptamer-based probes. This review summarizes their application in cancer diagnostics and treatments based on different localization of target biomarkers, as well as current challenges and future prospects.

Isolipoic acid-linked gold nanoparticles bearing the thomsen friedenreich tumor-associated carbohydrate antigen: Stability and in vitro studies

We have previously prepared gold nanoparticles (AuNPs) bearing the Thomsen-Friedenreich antigen disaccharide (TF_ag), a pan-carcinoma, Tumor-Associated Carbohydrate Antigen (TACA), as tools for various assays and biological applications. Conjugation to AuNPs typically involves the use of thiols due to the affinity of sulfur for the gold surface of the nanoparticle. While a use of a single thiol-containing ligand bound to the gold surface is standard practice, several studies have shown that ligands bearing multiple thiols can enhance the strength of the conjugation in a nearly linear fashion. (R)-(+)-α-Lipoic acid (LA), a naturally occurring disulfide-containing organic acid that is used as a cofactor in many enzymatic reactions, has been used as a linker to conjugate various molecules to AuNPs through its branched di-thiol system to enhance nanoparticle stability. We sought to use a similar system to increase nanoparticle stability that was devoid of the chiral center in (R)-(+)-α-lipoic acid. Isolipoic acid, an isomer of LA, where the exocyclic pentanoic acid chain is shifted by one carbon on the dithiolane ring to produce an achiral acid, was thought to act similarly as LA without the risk of any contaminating (L)-(−) isomer. We synthesized AuNPs with ligands of both serine and threonine glycoamino acids bearing the TF_ag linked to isolipoic acid and examined their stability under various conditions. In addition, these particles were shown to bind to Galectin-3 and inhibit the interaction of Galectin-3 with a protein displaying copies of the TF_ag. These agents should prove useful in the design of potential antimetastatic therapeutics that would benefit from achiral linkers that are geometrically linear and achiral.

Rational Design of T-Cell- and B-Cell-Based Therapeutic Cancer Vaccines

Cancer vaccines provide an efficient strategy to enhance tumor-specific immune responses by redeploying immune systems. Despite the approval of the first cancer vaccine (Sipuleucel-T) by the U.S. Food and Drug Administration in 2010, most therapeutic cancer vaccines fail in clinical trials. Basically, tumor-specific immune responses rely on not only T-cell but also B-cell immunity, which indicates that cancer vaccines should leverage both arms of the adaptive immune system. For example, CD8⁺ T cells activated by antigen-presenting cells (APCs) recognize and directly kill tumor cells via peptide-bound major histocompatibility complex (pMHC). B cells recognize antigen with no need of pMHC and require CD4⁺ T cells for sufficient activation and antibody generation, enabling antibody-mediated nondirect killing on tumor cells. Considering the different mechanisms of T-cell and B-cell activation, the rational design of therapeutic cancer vaccines should consider several factors, including antigen selection and recognition, immune activation, vaccine delivery, and repeatable vaccination, which can be advanced by chemical strategies.In this Account, we summarize our recent contributions to the development of effective T-cell- and B-cell-based therapeutic cancer vaccines. For T-cell-based vaccines, we focus on adjuvants as the key component for controllable APC activation and T-cell priming. Not only synthetic molecular agonists of pattern recognition receptors (PRRs) but also adjuvant nanomaterials were explored to satisfy diversiform vaccine designs. For example, a type of natural cyclic dinucleotide (CDN) that was chemically modified with fluorination and ipsilateral phosphorothioation to activate the stimulator of interferon gene (STING) was found to mediate antitumor responses. It retains structural similarity to the parent CDN scaffold but possesses increased stability, cellular uptake, and immune activation for antitumor treatment. It also facilitates facile conjugation with other agonists, which not only enhances APC-targeting delivery but also balances cellular and humoral antitumor responses. We also explored the intrinsic properties of nanomaterials that allow them to serve as adjuvants. A black phosphorus nanosheet-based nanovaccine was constructed and found to strongly potentiate antigen-specific T-cell antitumor immune responses through multiple immune-potentiating properties, leading to a highly integrated nanomaterial-based adjuvant design. For B-cell-based vaccines, multicomponent and multivalent strategies were applied to improve the immunogenicity. A multicomponent linear vaccine conjugate coordinates helper T (Th) cells and APCs to proliferate and differentiates B cells for enhanced antitumor immunoglobulin G antibody responses. To further improve antigen recognition, clustered designs on a multivalent epitope were applied by generating various structures, including branched lysine-based peptides, natural multivalent scaffold molecules, and self-assembled nanofibers. We also engineered nano- and microvaccine systems to optimize systemic and localized vaccination. A multilayer-assembled nanovaccine successfully integrated antigens and multiple agonists to modulate APC activation. A DNA hydrogel contributed to the control of APC's immune behaviors, including cell recruitment, activation, and migration, and induced robust antitumor responses as an all-in-one designable platform. In this Account, by summarizing strategies for both T-cell- and B-cell-based vaccine design, we not only compare the differences but also address the intrinsic uniformity between such vaccine designs and further discuss the potential of a combined T-cell- and B-cell-based vaccine, which highlights the applicability and feasibility of chemical strategies.

Ultrasensitive dual-signal electrochemical ratiometric aptasensor based on Co-MOFs with intrinsic self-calibration property for Mucin 1

The concentration of tumor biomarker Mucin 1 (MUC 1) is highly related with many diseases, which can be employed for the early diagnosis of cancer. In this paper, an electrochemical ratiometric aptasensor with intrinsic self-calibration property for the detection of MUC 1 is presented. In this paper, Co-MOFs themselves were employed as signal substances. This strategy was fabricated by using gold nanoparticles@black phosphorus (BP) as the substrate on the electrode, followed by modification of DNA nanotetrahedrons (DTN) via Au-S bond. The terminal of DTN contains MUC 1 aptamer. In the presence of MUC 1, the signal of DNA-labeled Co-MOFs can be detected. The current signal of Co-MOFs increased and that of thionine (as reference) was unchanged upon the addition of MUC 1. Thus, an intrinsic self-calibration aptasensor was achieved. In order to simplify the modification procedure, the electrolyte solution thionine was employed as an inner reference probe. Moreover, coupling of the hybridization chain reaction (HCR) with these MOFs signal tags presents an enzyme-free method for signal amplification, endowing the proposed ratiometric biosensor detection with high reproducibility and high sensitivity. The current ratio (I_IR/I_SP) remained stable over 30 individual measurements performed on ten different working electrodes. Even ten repeated scans performed on a single electrode exhibited a constant current ratio. The electrochemical ratiometric aptasensor is highly sensitivity for MUC 1 with the detection limit of 1.34 fM. Our proposed ratiometric sensor has great potential for the detection of cancer-related biomarkers.

A self-adjuvanting anti-tumor nanoliposomal vaccine based on fluorine-substituted MUC1 glycopeptide

Herein, a self-adjuvanting fluorinated MUC1-based nanoliposomal antitumor vaccine was constructed for the first time. Both the tumor-associated antigen and the mode of its presentation affect the immune response for antitumor vaccines.

Precise immunological evaluation rationalizes the design of a self-adjuvanting vaccine composed of glycan antigen, TLR1/2 ligand, and T-helper cell epitope

Sialyl-Tn (STn), overexpressed on various tumors, has been investigated for its application in anti-cancer vaccine therapy. However, Theratope, an STn-based vaccine, failed in the phase III clinical trial due to poor immunogenicity and epitope suppression by the foreign carrier protein. We therefore developed a self-adjuvanting STn based-vaccine, a conjugate of clustered STn (triSTn) antigen, TLR1/2 ligand (Pam₃CSK₄), and T-helper (Th) cell epitope, and found that this three-component self-adjuvanting vaccine effectively resulted in the production of anti-triSTn IgG antibodies. We herein analyzed immune responses induced by this self-adjuvanting vaccine in detail. We newly synthesized two-component vaccines, i.e., Pam₃CSK₄- or Th epitope-conjugated triSTn, as references to evaluate the immune-stimulating functions of Pam₃CSK₄ and Th epitope. Immunological evaluation of the synthesized vaccine candidates revealed that Pam₃CSK₄ was essential for antibody production, indicating that the uptake of triSTn antigen by antigen-presenting cells (APCs) was promoted by the recognition of Pam₃CSK₄ by TLR1/2. The function of the Th epitope was also confirmed. Th cell activation was important for boosting antibody production and IgG subclass switching. Furthermore, flow cytometric analyses of immune cells, including T cells, B cells, dendritic cells, and other monocytes, were first employed in the evaluation of self-adjuvanting vaccines and revealed that the three-component vaccine was able to induce antigen-specific immune responses for efficient antibody production without excessive inflammatory responses. Importantly, the co-administration of Freund's adjuvants was suggested to cause excessive myeloid cell accumulation and decreased plasma cell differentiation. These results demonstrate that vaccines can be designed to achieve the desired immune responses via the bottom-up construction of each immune element.

Detailed analysis of a three-component self-adjuvanting vaccine revealed that conjugate vaccines can be designed to achieve the desired immune responses via bottom-up construction of the necessary immune elements.

Efficiently Computing NMR 1H and 13C Chemical Shifts of Saccharides in Aqueous Environment

Determining the structure of saccharides in their native environment is crucial to understanding their function and more accurately targeting their utilization. Nuclear magnetic resonance observables such as the nuclear Overhauser effect or spin-spin coupling constants are routinely utilized to study saccharides in their native water environment. However, while highly sensitive to the local environment, chemical shifts are mostly overlooked, despite being commonly measured for compounds identification. Although chemical shifts carry considerable structural information, their direct association with structure is notoriously difficult. This is mostly due to the similarity in the chemical nature of most saccharides causing similar physicochemical environments close to sugar C and H atoms, resulting in comparable chemical shifts. The rise of computational power allows one to compute reliable chemical shifts and use them to determine atomistic details of these sugars in solution. However, any prediction is severely limited by the computational protocol used and its accuracy. In this work, we studied a set of 31 saccharides on which we evaluated various computational protocols to calculate the total number of 375 ¹H and 327 ¹³C chemical shifts of sugars in an aqueous environment. Our study proposes two cost-effective protocols for simulating ¹H and ¹³C chemical shifts that we recommend for further use. These protocols can help with the interpretation of experimental spectra, but we also show that they are also capable of structure prediction independently. This is possible because of the low mean absolute deviations of calculated shifts from the experiment (0.06 ppm for ¹H and 1.09 ppm for ¹³C). We explore different solvation methods, basis sets, and optimization schemes to reach such accuracy. A correct sampling of the conformation phase space of flexible sugar molecules is also key to obtaining accurately converged theoretical chemical shifts. The linear regression method was applied to convert the calculated isotropic nuclear magnetic shielding constants to simulated chemical shifts comparable with the experiment. The achieved level of accuracy can help in utilizing chemical shifts for elucidating the 3D atomistic structure of saccharides in aqueous solutions. All linear regression parameters obtained on our extensive set of sugars for all the tested protocols can be reutilized in future works.

The Shape of Nanostructures Encodes Immunomodulation of Carbohydrate Antigen and Vaccine Development

Gold nanoparticles (AuNPs) have shown remarkable potential for vaccine development, but the influence of the size and shape of nanoparticles modulating the T-cell-dependent carbohydrate antigen processing and immunomodulation is poorly investigated. Here, we described how different shapes and sizes of gold nanostructures carrying adjuvant modulate carbohydrate-based antigen processing in murine dendritic cells (mDCs) and subsequent T-cell activation produce a robust antibody response. As a prototype, CpG-adjuvant-coated spherical and rod- and star-shaped AuNPs were conjugated to the tripodal Tn-glycopeptide antigen to study their DC uptake and activation of T-cells in a DCs/T-cell co-culture assay. Our results showed that the spherical and star-shaped AuNPs displayed relatively weak receptor-mediated uptake and endosomal sequestration; however, they induced a high level of T helper-1 (Th1) biasing immune responses compared with rod-shaped AuNPs. Furthermore, the in vivo administration of AuNPs showed that the small spherical and star-shaped AuNPs induced an effective anti-Tn-glycopeptide immunoglobulin (IgG) antibody response compared with rod-shaped AuNPs. These results indicated that one could obtain superior carbohydrate vaccines by varying the shape and size parameters of nanostructures.

Alum Adjuvant and Built-in TLR7 Agonist Synergistically Enhance Anti-MUC1 Immune Responses for Cancer Vaccine

The tumor-associated antigen mucin 1 (MUC1) is an attractive target of antitumor vaccine, but its weak immunogenicity is a big challenge for the development of vaccine. In order to enhance immune responses against MUC1, herein, we conjugated small molecular toll-like receptor 7 agonist (TLR7a) to carrier protein BSA via MUC1 glycopeptide to form a three-component conjugate (BSA-MUC1-TLR7a). Furthermore, we combined the three-component conjugate with Alum adjuvant to explore their synergistic effects. The immunological studies indicated that Alum adjuvant and built-in TLR7a synergistically enhanced anti-MUC1 antibody responses and showed Th1-biased immune responses. Meanwhile, antibodies elicited by the vaccine candidate effectively recognized tumor cells and induced complement-dependent cytotoxicity. In addition, Alum adjuvant and built-in TLR7a synergistically enhanced MUC1 glycopeptide-specific memory CD8+ T-cell immune responses. More importantly, the vaccine with the binary adjuvant can significantly inhibit tumor growth and prolong the survival time of mice in the tumor challenge experiment. This novel vaccine construct provides an effective strategy to develop antitumor vaccines.

Chimeric virus-like particles presenting tumour-associated MUC1 epitope result in high titers of specific IgG antibodies in the presence of squalene oil-in-water adjuvant: towards safe cancer immunotherapy

Background

Immunotherapy is emerging as a powerful treatment approach for several types of cancers. Modulating the immune system to specifically target cancer cells while sparing healthy cells, is a very promising approach for safer therapies and increased survival of cancer patients. Tumour-associated antigens are favorable targets for cancer immunotherapy, as they are exclusively expressed by the cancer cells, minimizing the risk of an autoimmune reaction. The ability to initiate the activation of the immune system can be achieved by virus-like particles (VLPs) which are safe and potent delivery tools. VLP‐based vaccines have evolved dramatically over the last few decades and showed great potential in preventing infectious diseases. Immunogenic potency of engineered VLPs as a platform for the development of effective therapeutic cancer vaccines has been studied extensively. This study involves recombinant VLPs presenting multiple copies of tumour-specific mucin 1 (MUC1) epitope as a potentially powerful tool for future immunotherapy.

Results

In this report VLPs based on the structural protein of Norovirus (NoV VP1) were genetically modified to present multiple copies of tumour-specific MUC1 epitope on their surface. Chimeric MUC1 particles were produced in the eukaryotic Leishmania tarentolae expression system and used in combination with squalene oil-in-water emulsion MF59 adjuvant to immunize BALB/c mice. Sera from vaccinated mice demonstrated high titers of IgG and IgM antibodies which were specifically recognizing MUC1 antigen.

Conclusions

The obtained results show that immunization with recombinant chimeric NoV VP1- MUC1 VLPs result in high titers of MUC1 specific IgG antibodies and show great therapeutic potential as a platform to present tumour-associated antigens.

Graphical Abstract

MUC1 Specific Immune Responses Enhanced by Coadministration of Liposomal DDA/MPLA and Lipoglycopeptide

Mucin 1 (MUC1), a well-known tumor-associated antigen and attractive target for tumor immunotherapy, is overexpressed in most human epithelial adenomas with aberrant glycosylation. However, its low immunogenicity impedes the development of MUC1-targeted antitumor vaccines. In this study, we investigated three liposomal adjuvant systems containing toll-like receptor 4 (TLR4) agonist monophosphoryl lipid A (MPLA) and auxiliary lipids of different charges: cationic lipid dimethyldioctadecylammonium (DDA), neutral lipid distearoylglycerophosphocholine (DSPC) or anionic lipid dioleoylphosphatidylglycerol (DOPG), respectively. ELISA assay evidenced that the positively charged DDA/MPLA liposomes are potent immune activators, which induced remarkable levels of anti-MUC1 antibodies and exhibited robust Th1-biased immune responses. Importantly, the antibodies induced by DDA/MPLA liposomes efficiently recognized and killed MUC1-positive tumor cells through complement-mediated cytotoxicity. In addition, antibody titers in mice immunized with P2-MUC1 vaccine were significantly higher than those from mice immunized with P1-MUC1 or MUC1 vaccine, which indicated that the lipid conjugated on MUC1 antigen also played important role for immunomodulation. This study suggested that the liposomal DDA/MPLA with lipid-MUC1 is a promising antitumor vaccine, which can be used for the immunotherapy of various epithelial carcinomas represented by breast cancer.

The Development of Vaccines from Synthetic Tumor-Associated Mucin Glycopeptides and their Glycosylation-Dependent Immune Response

Tumor-associated carbohydrate antigens are overexpressed as altered-self in most common epithelial cancers. Their glycosylation patterns differ from those of healthy cells, functioning as an ID for cancer cells. Scientists have been developing anti-cancer vaccines based on mucin glycopeptides, yet the interplay of delivery system, adjuvant and tumor associated MUC epitopes in the induced immune response is not well understood. The current state of the art suggests that the identity, abundancy and location of the glycans on the MUC backbone are all key parameters in the cellular and humoral response. This review shares lessons learned by us in over two decades of research in glycopeptide vaccines. By bridging synthetic chemistry and immunology, we discuss efforts in designing synthetic MUC1/4/16 vaccines and focus on the role of glycosylation patterns. We provide a brief introduction into the mechanisms of the immune system and aim to promote the development of cancer subunit vaccines.

Design, synthesis, and initial immunological evaluation of glycoconjugates based on saponin adjuvants and the Tn antigen

We report the first synthesis and immunological evaluation of a new glycoconjugate design based on streamlined saponin adjuvants and the Tn carbohydrate antigen. While the novel synthetic constructs induced moderate antibody responses in mice, the versatile chemical platform is amenable to further structure-activity optimizations for the development of self-adjuvanting glycoconjugate cancer vaccines.

Structure-based Design of Anti-cancer Vaccines: The Significance of Antigen Presentation to Boost the Immune Response

Immunotherapy, alone or in combination with other therapies, is widely used against cancer. Glycoprotein Mucin 1 (MUC1), which is overexpressed and aberrantly glycosylated in tumor cells, is one of the most promising candidates to engineer new cancer vaccines. In this context, the development of stable antigens that can elicit a robust immune response is mandatory. Here, we describe the design and in vivo biological evaluation of three vaccine candidates based on MUC1 glycopeptides that comprise unnatural elements in their structure. By placing the Tn antigen (GalNAcα-O-Ser/Thr) at the center of the design, the chemical modifications include changes to the peptide backbone, glycosidic linkage, and at the carbohydrate level. Significantly, the three vaccines elicit robust immune responses in mice and produce antibodies that can be recognized by several human cancer cells. In all cases, a link was stablished between the conformational changes induced by the new elements in the antigen presentation and the immune response induced in mice. According to our data, the development of effective MUC1-based vaccines should use surrogates that mimic the conformational space of aberrantly glycosylated MUC1 glycopeptides found in tumors.

Advanced and Innovative Nano-Systems for Anticancer Targeted Drug Delivery

The encapsulation of therapeutic agents into nano-based drug delivery system for cancer treatment has received considerable attention in recent years. Advancements in nanotechnology provide an opportunity for efficient delivery of anticancer drugs. The unique properties of nanoparticles not only allow cancer-specific drug delivery by inherent passive targeting phenomena and adopting active targeting strategies, but also improve the pharmacokinetics and bioavailability of the loaded drugs, leading to enhanced therapeutic efficacy and safety compared to conventional treatment modalities. Small molecule drugs are the most widely used anticancer agents at present, while biological macromolecules, such as therapeutic antibodies, peptides and genes, have gained increasing attention. Therefore, this review focuses on the recent achievements of novel nano-encapsulation in targeted drug delivery. A comprehensive introduction of intelligent delivery strategies based on various nanocarriers to encapsulate small molecule chemotherapeutic drugs and biological macromolecule drugs in cancer treatment will also be highlighted.

Cyclodextrins-Peptides/Proteins Conjugates: Synthesis, Properties and Applications

Cyclodextrins (CDs) are a family of macrocyclic oligosaccharides mostly composed of six, seven, or eight α-D-glucopyranose units with α-1,4-glycosidic bonds to form toroidal structures. The CDs possess a hydrophilic exterior and hydrophobic interior with the ability to form an inclusion complex, especially with hydrophobic molecules. However, most existing studies are about conjugation CDs with peptide/protein focusing on the formation of new systems. The CD-peptide/protein can possess new abilities; particularly, the cavity can be applied in modulation properties of more complexed proteins. Most studies are focused on drug delivery, such as targeted delivery in cell-penetrating peptides or co-delivery. The co-delivery is based mostly on polylysine systems; on the other hand, the CD-peptide allows us to understand biomolecular mechanisms such as fibryllation or stem cell behaviour. Moreover, the CD-proteins are more complexed systems with a focus on targeted therapy; these conjugates might be controllable with various properties due to changes in their stability. Finally, the studies of CD-peptide/protein are promising in biomedical application and provide new possibilities for the conjugation of simple molecules to biomolecules.

Recent advances on smart glycoconjugate vaccines in infections and cancer

Vaccination is one of the greatest achievements in biomedical research preventing death and morbidity in many infectious diseases through the induction of pathogen-specific humoral and cellular immune responses. Currently, no effective vaccines are available for pathogens with a highly variable antigenic load, such as the human immunodeficiency virus or to induce cellular T-cell immunity in the fight against cancer. The recent SARS-CoV-2 outbreak has reinforced the relevance of designing smart therapeutic vaccine modalities to ensure public health. Indeed, academic and private companies have ongoing joint efforts to develop novel vaccine prototypes for this virus. Many pathogens are covered by a dense glycan-coat, which form an attractive target for vaccine development. Moreover, many tumor types are characterized by altered glycosylation profiles that are known as "tumor-associated carbohydrate antigens". Unfortunately, glycans do not provoke a vigorous immune response and generally serve as T-cell-independent antigens, not eliciting protective immunoglobulin G responses nor inducing immunological memory. A close and continuous crosstalk between glycochemists and glycoimmunologists is essential for the successful development of efficient immune modulators. It is clear that this is a key point for the discovery of novel approaches, which could significantly improve our understanding of the immune system. In this review, we discuss the latest advancements in development of vaccines against glycan epitopes to gain selective immune responses and to provide an overview on the role of different immunogenic constructs in improving glycovaccine efficacy.

Mucins as anti-cancer targets: perspectives of the glycobiologist

Mucins are highly O-glycosylated glycoproteins that carry a heterogenous variety of O-glycan structures. Tumor cells tend to overexpress specific mucins, such as the cell surface mucins MUC1 and MUC4 that are engaged in signaling and cell growth, and exhibit abnormal glycosylation. In particular, the Tn and T antigens and their sialylated forms are common in cancer mucins. We review herein methods chosen to use cancer-associated glycans and mucins as targets for the design of anti-cancer immunotherapies. Mucin peptides from the glycosylated and transmembrane domains have been combined with immune-stimulating adjuvants in a wide variety of approaches to produce anti-tumor antibodies and vaccines. These mucin conjugates have been tested on cancer cells in vitro and in mice with significant successes in stimulating anti-tumor responses. The clinical trials in humans, however, have shown limited success in extending survival. It seems critical that the individual-specific epitope expression of cancer mucins is considered in future therapies to result in lasting anti-tumor responses.

The Adjuvant of α-Galactosylceramide Presented by Gold Nanoparticles Enhances Antitumor Immune Responses of MUC1 Antigen-Based Tumor Vaccines

BACKGROUND

Therapeutic tumor vaccines are one of the most promising strategies and have attracted great attention in cancer treatment. However, most of them have shown unsatisfactory immunogenicity, there are still few available vaccines for clinical use. Therefore, there is an urgent demand to develop novel strategies to improve the immune efficacy of antitumor vaccines.

PURPOSE

This study aimed to develop novel adjuvants and carriers to enhance the immune effect of MUC1 glycopeptide antigen-based antitumor vaccines.

METHODS

An antitumor vaccine was developed, in which MUC1 glycopeptide was used as tumor-associated antigen, α-GalCer served as an immune adjuvant and AuNPs was a multivalent carrier.

RESULTS

Immunological evaluation results indicated that the constructed vaccines enabled a significant antibody response. FACS analysis and immunofluorescence assay showed that the induced antisera exhibited a specific binding with MUC1 positive MCF-7 cells. Moreover, the induced antibody can mediate CDC to kill MCF-7 cells. Besides stimulating B cells to produce MUC1-specific antibodies, the prepared vaccines also induced MUC1-specific CTLs in vitro. Furthermore, the vaccines significantly delayed tumor development in tumor-bearing mice model.

CONCLUSION

These results showed that the construction of vaccines by presenting α-GalCer adjuvant and an antigen on gold nanoparticles offers a potential strategy to improve the antitumor response in cancer immunotherapy.

Heterologous prime-boost immunization co-targeting dual antigens inhibit tumor growth and relapse

Therapeutic cancer vaccines aim to induce an effective immune response against cancer, and the effectiveness of these vaccines is influenced by the choice of immunogen, vaccine type, and immunization strategy. Although treatment with cancer vaccines can improve tumor burden and survival, in most animal studies, it is challenging to achieve a complete response against tumor growth and recurrence, without the use of other therapies in combination. Here, we present a novel approach where dual antigens (survivin and MUC1) are co-targeted using three DNA vaccines, followed by a single booster of a recombinant modified vaccinia Ankara (MVA) vaccine. This heterologous vaccination strategy induced higher levels of interferon (IFN)-γ-secretion and stronger antigen-specific T-cell responses than those induced individually by the DNA vaccines and the MVA vaccine in mice. This strategy also increased the number of active tumor-infiltrating T cells that efficiently inhibit tumor growth in tumor-bearing mice. Heterologous DNA prime-MVA boost immunization was capable of inducing a robust antigen-specific immune-memory, as seen from the resistance to subsequent survivin- and MUC1-expressing tumors. Moreover, the therapeutic effects of DNA prime-MVA boost and DNA prime-adenovirus boost strategies were compared. DNA prime-MVA boost immunization performed better, as indicated by the T effector ratio and the induction of Th1 immunity. This study provides the basis for the use of heterologous DNA prime-MVA boost vaccination regime targeting two antigens simultaneously as a promising immunotherapeutic strategy against cancer.

Machine-Driven Chemoenzymatic Synthesis of Glycopeptide

Historically, researchers have put considerable effort into developing automation systems to prepare natural biopolymers such as peptides and oligonucleotides. The availability of such mature systems has significantly advanced the development of natural science. Over the past twenty years, breakthroughs in automated synthesis of oligosaccharides have also been achieved. A machine-driven platform for glycopeptide synthesis by a reconstructed peptide synthesizer is described. The designed platform is based on the use of an amine-functionalized silica resin to facilitate the chemical synthesis of peptides in organic solvent as well as the enzymatic synthesis of glycan epitopes in the aqueous phase in a single reaction vessel. Both syntheses were performed by a peptide synthesizer in a semiautomated manner.

A review on development of MUC1-based cancer vaccine

Mucin 1 (MUC1) is a transmembrane mucin glycoprotein expressed on the surface of almost all epithelial cells. Aberrantly glycosylated MUC1 is associated with cellular transformation from a normal to malignant phenotype in human cancers. Therefore, MUC1 is the major target for the design and development of cancer vaccines. MUC1-based cancer vaccines are a promising strategy for preventing cancer progression and metastasis. This review summarizes the most significant milestones achieved to date in the development of different MUC-1-based vaccine approaches in clinical trials. Further, it provides perspectives for future research that may promote clinical advances in infection-associated cancers.

Selective modification of sulfamidate-containing peptides

Hybrid peptides whose N-terminal residues are activated in the form of α-methylisoserine-derived cyclic sulfamidates exhibit rich reactivity as electrophiles, allowing site- and stereoselective modifications at different backbone and side chain positions. The unique properties of this scaffold allow the stereocontrolled late-stage functionalization of the peptide backbone by nucleophilic ring opening with fluorescent probes, thiocarbohydrates and tags for strain-promoted azide-alkyne cycloaddition as well as by installing labile N-terminal affinity tags (biotin) and cytotoxic drugs (chlorambucil) for pH-controlled release. Finally, an unexpected base-promoted acyl group migration from the sulfamidate N-terminus allows fast and quantitative intramolecular modification of nucleophilic side chains on the fully unprotected peptides.

Aberrant glycosylation patterns on cancer cells: Therapeutic opportunities for glycodendrimers/metallodendrimers oncology

Despite exciting discoveries and progresses in drug design against cancer, its cure is still rather elusive and remains one of the humanities major challenges in health care. The safety profiles of common small molecule anti-cancer therapeutics are less than at acceptable levels and limiting deleterious side-effects have to be urgently addressed. This is mainly caused by their incapacity to differentiate healthy cells from cancer cells; hence, the use of high dosage becomes necessary. One possible solution to improve the therapeutic windows of anti-cancer agents undoubtedly resides in modern nanotechnology. This review presents a discussion concerning multivalent carbohydrate-protein interactions as this topic pertains to the fundamental aspects that lead glycoscientists to tackle glyconanoparticles. The second section describes the detailed properties of cancer cells and how their aberrant glycan surfaces differ from those of healthy cells. The third section briefly describes the immune systems, both innate and adaptative, because the numerous displays of cell surface protein receptors necessitate to be addressed from the multivalent angles, a strength full characteristic of nanoparticles. The next chapter presents recent advances in glyconanotechnologies, including glycodendrimers in particular, as they apply to glycobiology and carbohydrate-based cancer vaccines. This was followed by an overview of metallodendrimers and how this rapidly evolving field may contribute to our arsenal of therapeutic tools to fight cancer. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Design, Synthesis, and Preliminary Immunological Studies of MUC1-Based Antitumor Vaccines Adjuvanted with R- and S-FSL-1

Fibroblast stimulating lipopeptide 1 (FSL-1) is the ligand of TLR2 and TLR6 and can be used as the vaccine adjuvant to prepare antitumor vaccines. However, FSL-1 is a stereoisomeric mixture that contains the R stereoisomer and S stereoisomer, and it is still unclear which stereoisomer has better adjuvant activities. In this work, we designed and synthesized MUC1-based antitumor vaccines adjuvanted with the stereoisomers R-FSL-1 and S-FSL-1, which were synthesized from the stereoisomeric building blocks R-Fmoc-Pam₂Cys-OH and S-Fmoc-Pam₂Cys-OH, respectively. Immunological evaluation indicated that both R-FSL-1 and S-FSL-1 can be used as adjuvants for the construction of MUC1-based antitumor vaccines, with R-FSL-1 showing a better adjuvant effect than S-FSL-1.

Recent Advances in Peptide-Based Approaches for Cancer Treatment

BACKGROUND

Peptide-based pharmaceuticals have recently experienced a renaissance due to their ability to fill the gap between the two main classes of available drugs, small molecules and biologics. Peptides combine the high potency and selectivity typical of large proteins with some of the characteristic advantages of small molecules such as synthetic accessibility, stability and the potential of oral bioavailability.

METHODS

In the present manuscript we review the recent literature on selected peptide-based approaches for cancer treatment, emphasizing recent advances, advantages and challenges of each strategy.

RESULTS

One of the applications in which peptide-based approaches have grown rapidly is cancer therapy, with a focus on new and established targets. We describe, with selected examples, some of the novel peptide-based methods for cancer treatment that have been developed in the last few years, ranging from naturally-occurring and modified peptides to peptidedrug conjugates, peptide nanomaterials and peptide-based vaccines.

CONCLUSION

This review brings out the emerging role of peptide-based strategies in oncology research, critically analyzing the advantages and limitations of these approaches and the potential for their development as effective anti-cancer therapies.

Esophageal, gastric and colorectal cancers: Looking beyond classical serological biomarkers towards glycoproteomics-assisted precision oncology

Esophageal (OC), gastric (GC) and colorectal (CRC) cancers are amongst the digestive track tumors with higher incidence and mortality due to significant molecular heterogeneity. This constitutes a major challenge for patients' management at different levels, including non-invasive detection of the disease, prognostication, therapy selection, patient's follow-up and the introduction of improved and safer therapeutics. Nevertheless, important milestones have been accomplished pursuing the goal of molecular-based precision oncology. Over the past five years, high-throughput technologies have been used to interrogate tumors of distinct clinicopathological natures, generating large-scale biological datasets (e.g. genomics, transcriptomics, and proteomics). As a result, GC and CRC molecular subtypes have been established to assist patient stratification in the clinical settings. However, such molecular panels still require refinement and are yet to provide targetable biomarkers. In parallel, outstanding advances have been made regarding targeted therapeutics and immunotherapy, paving the way for improved patient care; nevertheless, important milestones towards treatment personalization and reduced off-target effects are also to be accomplished. Exploiting the cancer glycoproteome for unique molecular fingerprints generated by dramatic alterations in protein glycosylation may provide the necessary molecular rationale towards this end. Therefore, this review presents functional and clinical evidences supporting a reinvestigation of classical serological glycan biomarkers such as sialyl-Tn (STn) and sialyl-Lewis A (SLe^A) antigens from a tumor glycoproteomics perspective. We anticipate that these glycobiomarkers that have so far been employed in non-invasive cancer prognostication may hold unexplored value for patients' management in precision oncology settings.

Synthesis, conformational analysis and in vivo assays of an anti-cancer vaccine that features an unnatural antigen based on an sp2-iminosugar fragment

The Tn antigen (GalNAc-α-1-O-Thr/Ser) is a well-known tumor-associated carbohydrate determinant. The use of glycopeptides that incorporate this structure has become a significant and promising niche of research owing to their potential use as anticancer vaccines. Herein, the conformational preferences of a glycopeptide with an unnatural Tn antigen, characterized by a threonine decorated with an sp²-iminosugar-type α-GalNAc mimic, have been studied both in solution, by combining NMR spectroscopy and molecular dynamics simulations, and in the solid state bound to an anti-mucin-1 (MUC1) antibody, by X-ray crystallography. The Tn surrogate can mimic the main conformer sampled by the natural antigen in solution and exhibits high affinity towards anti-MUC1 antibodies. Encouraged by these data, a cancer vaccine candidate based on this unnatural glycopeptide and conjugated to the carrier protein Keyhole Limpet Hemocyanin (KLH) has been prepared and tested in mice. Significantly, the experiments in vivo have proved that this vaccine elicits higher levels of specific anti-MUC1 IgG antibodies than the analog that bears the natural Tn antigen and that the elicited antibodies recognize human breast cancer cells with high selectivity. Altogether, we compile evidence to confirm that the presentation of the antigen, both in solution and in the bound state, plays a critical role in the efficacy of the designed cancer vaccines. Moreover, the outcomes derived from this vaccine prove that there is room for exploring further adjustments at the carbohydrate level that could contribute to designing more efficient cancer vaccines.

An anti-cancer vaccine based on an unnatural antigen with an sp²-iminosugar fragment.

Multifunctional Protein Conjugates with Built-in Adjuvant (Adjuvant-Protein-Antigen) as Cancer Vaccines Boost Potent Immune Responses

Many cancer vaccines are not successful in clinical trials, mainly due to the challenges associated with breaking immune tolerance. Herein, we report a new strategy using an adjuvant-protein-antigen (three-in-one protein conjugates with built-in adjuvant) as an anticancer vaccine, in which both the adjuvant (small-molecule TLR7 agonist) and tumor-associated antigen (mucin 1, MUC1) are covalently conjugated to the same carrier protein (BSA). It is shown that the protein conjugates with built-in adjuvant can increase adjuvant's stimulation, prevent adjuvant's systemic toxicities, facilitate the codelivery of adjuvants and antigens, and enhance humoral and cellular immune responses. The IgG antibody titers elicited by the self-adjuvanting three-in-one protein conjugates were significantly higher than those elicited by the vaccine mixed with TLR7 agonist (more than 15-fold) or other traditional adjuvants. Importantly, the potent immune responses against cancer cells suggest that this new vaccine construct is an effective strategy for the personalized antitumor immunotherapy.

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Adjuvant-protein-antigen protein conjugates act as new cancer vaccine strategy

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Built-in adjuvant of TLR7 agonist can reduce toxicities and enhance immune stimulations

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Three-in-one protein conjugates boost potent immune responses against cancer cells

Specificity of human natural antibodies referred to as anti-Tn

To understand the role of human natural IgM known as antibodies against the carbohydrate epitope Tn, the antibodies were isolated using GalNAcα-Sepharose affinity chromatography, and their specificity was profiled using microarrays (a glycan array printed with oligosaccharides and bacterial polysaccharides, as well as a glycopeptide array), flow cytometry, and inhibition ELISA. The antibodies bound a restricted number of GalNAcα-terminated oligosaccharides better than the parent monosaccharide, e.g., 6-O-Su-GalNAcα and GalNAcα1-3Galβ1-3(4)GlcNAcβ. The binding with several bacterial polysaccharides that have no structural resemblance to the affinity ligand GalNAcα was quite unexpected. Given that GalNAcα is considered the key fragment of the Tn antigen, it is surprising that these antibodies bind weakly GalNAcα-OSer and do not bind a wide variety of GalNAcα-OSer/Thr-containing mucin glycopeptides. At the same time, we have observed specific binding to cells having Tn-positive glycoproteins containing similar glycopeptide motifs in a conformationally rigid macromolecule. Thus, specific recognition of the Tn antigen apparently requires that the naturally occurring "anti-Tn" IgM recognize a complex epitope comprising the GalNAcα as an essential component and a fairly long amino acid sequence where the amino acids adjacent to GalNAcα do not contact the antibody paratope; i.e., the antibodies recognize a spatial epitope or a molecular pattern rather than a classical continuous sequence. In addition, we have not found any increase in the binding of natural antibodies when GalNAcα residues were clustered. These results may help in further development of anticancer vaccines based on synthetic Tn constructs.

Tumor-associated O-glycans of MUC1: Carriers of the glyco-code and targets for cancer vaccine design

The transformation from normal to malignant phenotype in human cancers is associated with aberrant cell-surface glycosylation. It has frequently been reported that MUC1, the heavily glycosylated cell-surface mucin, is altered in both, expression and glycosylation pattern, in human carcinomas of the epithelium. The presence of incomplete or truncated glycan structures, often capped by sialic acid, commonly known as tumor-associated carbohydrate antigens (TACAs), play a key role in tumor initiation, progression, and metastasis. Accumulating evidence suggests that expression of TACAs is associated with tumor escape from immune defenses. In this report, we will give an overview of the oncogenic functions of MUC1 that are exerted through TACA interactions with endogenous carbohydrate-binding proteins (lectins). These interactions often lead to creation of a pro-tumor microenvironment, favoring tumor progression and metastasis, and tumor evasion. In addition, we will describe current efforts in the design of cancer vaccines with special emphasis on synthetic MUC1 glycopeptide vaccines. Analysis of the key factors that govern structure-based design of immunogenic MUC1 glycopeptide epitopes are described. The role of TACA type, position, and density on observed humoral and cellular immune responses is evaluated.

Phage display as a tool for vaccine and immunotherapy development

Bacteriophages, or phages, are viruses that specifically infect bacteria and coopt the cellular machinery to create more phage proteins, eventually resulting in the release of new phage particles. Phages are heavily utilized in bioengineering for applications ranging from tissue engineering scaffolds to immune signal delivery. Of specific interest to vaccines and immunotherapies, phages have demonstrated an ability to activate both the innate and adaptive immune systems. The genome of these viral particles can be harnessed for DNA vaccination, or the surface proteins can be exploited for antigen display. More specifically, genes that encode an antigen of interest can be spliced into the phage genome, allowing antigenic proteins or peptides to be displayed by fusion to phage capsid proteins. Phages therefore present antigens to immune cells in a highly ordered and repetitive manner. This review discusses the use of phage with adjuvanting activity as antigen delivery vehicles for vaccination against infectious disease and cancer.