Adjuvants for peptide-based cancer vaccines

Advances in therapeutic cancer vaccines: Harnessing immune adjuvants for enhanced efficacy and future perspectives

Preventive cancer vaccines are highly effective in preventing viral infection-induced cancer, but advances in therapeutic cancer vaccines with a focus on eliminating cancer cells through immunotherapy are limited. To develop therapeutic cancer vaccines, the integration of optimal adjuvants is a potential strategy to enhance or complement existing therapeutic approaches. However, conventional adjuvants do not satisfy the criteria of clinical trials for therapeutic cancer vaccines. To improve the effects of adjuvants in therapeutic cancer vaccines, effective vaccination strategies must be formulated and novel adjuvants must be identified. This review offers an overview of the current advancements in therapeutic cancer vaccines and highlights in situ vaccination approaches that can be synergistically combined with other immunotherapies by harnessing the adjuvant effects. Additionally, the refinement of adjuvant systems using cutting-edge technologies and the elucidation of molecular mechanisms underlying immunogenic cell death to facilitate the development of innovative adjuvants have been discussed.

Neoantigen Identification and Dendritic Cell-Based Vaccines for Lung Cancer Immunotherapy

Immunotherapies can treat many cancers, including difficult-to-treat cases such as lung cancer. Due to its tolerability, long-lasting therapeutic responses, and efficacy in a wide spectrum of patients, immunotherapy can also help to treat lung cancer, which has few treatment choices. Tumor-specific antigens (TSAs) for cancer vaccinations and T-cell therapies are difficult to discover. Neoantigens (NeoAgs) from genetic mutations, irregular RNA splicing, protein changes, or viral genetic sequences in tumor cells provide a solution. NeoAgs, unlike TSAs, are non-self and can cause an immunological response. Next-generation sequencing (NGS) and bioinformatics can swiftly detect and forecast tumor-specific NeoAgs. Highly immunogenic NeoAgs provide personalized or generalized cancer immunotherapies. Dendritic cells (DCs), which originate and regulate T-cell responses, are widely studied potential immunotherapeutic therapies for lung cancer and other cancers. DC vaccines are stable, reliable, and safe in clinical trials. The purpose of this article is to evaluate the current status, limitations, and prospective clinical applications of DC vaccines, as well as the identification and selection of major histocompatibility complex (MHC) class I and II genes for NeoAgs. Our goal is to explain DC biology and activate DC manipulation to help researchers create extremely potent cancer vaccines for patients.

Immunotherapeutic Strategies for the Treatment of Glioblastoma: Current Challenges and Future Perspectives

Despite decades of research and the best up-to-date treatments, grade 4 Glioblastoma (GBM) remains uniformly fatal with a patient median overall survival of less than 2 years. Recent advances in immunotherapy have reignited interest in utilizing immunological approaches to fight cancer. However, current immunotherapies have so far not met the anticipated expectations, achieving modest results in their journey from bench to bedside for the treatment of GBM. Understanding the intrinsic features of GBM is of crucial importance for the development of effective antitumoral strategies to improve patient life expectancy and conditions. In this review, we provide a comprehensive overview of the distinctive characteristics of GBM that significantly influence current conventional therapies and immune-based approaches. Moreover, we present an overview of the immunotherapeutic strategies currently undergoing clinical evaluation for GBM treatment, with a specific emphasis on those advancing to phase 3 clinical studies. These encompass immune checkpoint inhibitors, adoptive T cell therapies, vaccination strategies (i.e., RNA-, DNA-, and peptide-based vaccines), and virus-based approaches. Finally, we explore novel innovative strategies and future prospects in the field of immunotherapy for GBM.

Local Enrichment with Convergence of Enriched T-Cell Clones Are Hallmarks of Effective Peptide Vaccination against B16 Melanoma

BACKGROUND

Some peptide anticancer vaccines elicit a strong T-cell memory response but fail to suppress tumor growth. To gain insight into tumor resistance, we compared two peptide vaccines, p20 and p30, against B16 melanoma, with both exhibiting good in vitro T-cell responses but different tumor suppression abilities.

METHODS

We compared activation markers and repertoires of T-lymphocytes from tumor-draining (dLN) and non-draining (ndLN) lymph nodes for the two peptide vaccines.

RESULTS

We showed that the p30 vaccine had better tumor control as opposed to p20. p20 vaccine induced better in vitro T-cell responsiveness but failed to suppress tumor growth. Efficient antitumor vaccination is associated with a higher clonality of cytotoxic T-cells (CTLs) in dLNs compared with ndLNs and the convergence of most of the enriched clones. With the inefficient p20 vaccine, the most expanded and converged were clones of the bystander T-cells without an LN preference.

CONCLUSIONS

Here, we show that the clonality and convergence of the T-cell response are the hallmarks of efficient antitumor vaccination. The high individual and methodological dependencies of these parameters can be avoided by comparing dLNs and ndLNs.

Design and Evaluation of Synthetic Delivery Formulations for Peptide-Based Cancer Vaccines

With the recent advances in neoantigen identification, peptide-based cancer vaccines offer substantial potential in the field of immunotherapy. However, rapid clearance, low immunogenicity, and insufficient antigen-presenting cell (APC) uptake limit the efficacy of peptide-based cancer vaccines. This review explores the barriers hindering vaccine efficiency, highlights recent advancements in synthetic delivery systems, and features strategies for the key delivery steps of lymph node (LN) drainage, APC delivery, cross-presentation strategies, and adjuvant incorporation. This paper also discusses the design of preclinical studies evaluating vaccine efficiency, including vaccine administration routes and murine tumor models.

A Cancer Nanovaccine for Co-Delivery of Peptide Neoantigens and Optimized Combinations of STING and TLR4 Agonists

Immune checkpoint blockade (ICB) has revolutionized cancer treatment and led to complete and durable responses, but only for a minority of patients. Resistance to ICB can largely be attributed to insufficient number and/or function of antitumor CD8+ T cells in the tumor microenvironment. Neoantigen targeted cancer vaccines can activate and expand the antitumor T cell repertoire, but historically, clinical responses have been poor because immunity against peptide antigens is typically weak, resulting in insufficient activation of CD8+ cytotoxic T cells. Herein, we describe a nanoparticle vaccine platform that can overcome these barriers in several ways. First, the vaccine can be reproducibly formulated using a scalable confined impingement jet mixing method to coload a variety of physicochemically diverse peptide antigens and multiple vaccine adjuvants into pH-responsive, vesicular nanoparticles that are monodisperse and less than 100 nm in diameter. Using this approach, we encapsulated synergistically acting adjuvants, cGAMP and monophosphoryl lipid A (MPLA), into the nanocarrier to induce a robust and tailored innate immune response that increased peptide antigen immunogenicity. We found that incorporating both adjuvants into the nanovaccine synergistically enhanced expression of dendritic cell costimulatory markers, pro-inflammatory cytokine secretion, and peptide antigen cross-presentation. Additionally, the nanoparticle delivery increased lymph node accumulation and uptake of peptide antigen by dendritic cells in the draining lymph node. Consequently, nanoparticle codelivery of peptide antigen, cGAMP, and MPLA enhanced the antigen-specific CD8+ T cell response and delayed tumor growth in several mouse models. Finally, the nanoparticle platform improved the efficacy of ICB immunotherapy in a murine colon carcinoma model. This work establishes a versatile nanoparticle vaccine platform for codelivery of peptide neoantigens and synergistic adjuvants to enhance responses to cancer vaccines.

PLGA-PEI nanoparticle covered with poly(I:C) for personalised cancer immunotherapy

Melanoma is the main cause of death among skin cancers and its incidence worldwide has been experiencing an appalling increase. However, traditional treatments lack effectiveness in advanced or metastatic patients. Immunotherapy, meanwhile, has been shown to be an effective treatment option, but the rate of cancers responding remains far from ideal. Here we have developed a personalized neoantigen peptide-based cancer vaccine by encapsulating patient derived melanoma neoantigens in polyethylenimine (PEI)-functionalised poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) and coating them with polyinosinic:polycytidylic acid (poly(I:C)). We found that PLGA NPs can be effectively modified to be coated with the immunoadjuvant poly(I:C), as well as to encapsulate neoantigens. In addition, we found that both dendritic cells (DCs) and lymphocytes were effectively stimulated. Moreover, the developed NP was found to have a better immune activation profile than NP without poly(I:C) or without antigen. Our results demonstrate that the developed vaccine has a high capacity to activate the immune system, efficiently maturing DCs to present the antigen of choice and promoting the activity of lymphocytes to exert their cytotoxic function. Therefore, the immune response generated is optimal and specific for the elimination of melanoma tumour cells.

Glioblastoma vaccines: past, present, and opportunities

Glioblastoma (GBM) is one of the most lethal central nervous systems (CNS) tumours in adults. As supplements to standard of care (SOC), various immunotherapies improve the therapeutic effect in other cancers. Among them, tumour vaccines can serve as complementary monotherapy or boost the clinical efficacy with other immunotherapies, such as immune checkpoint blockade (ICB) and chimeric antigen receptor T cells (CAR-T) therapy. Previous studies in GBM therapeutic vaccines have suggested that few neoantigens could be targeted in GBM due to low mutation burden, and single-peptide therapeutic vaccination had limited efficacy in tumour control as monotherapy. Combining diverse antigens, including neoantigens, tumour-associated antigens (TAAs), and pathogen-derived antigens, and optimizing vaccine design or vaccination strategy may help with clinical efficacy improvement. In this review, we discussed current GBM therapeutic vaccine platforms, evaluated and potential antigenic targets, current challenges, and perspective opportunities for efficacy improvement.

Cancer vaccines in the clinic

Vaccines are an important tool in the rapidly evolving repertoire of immunotherapies in oncology. Although cancer vaccines have been investigated for over 30 years, very few have achieved meaningful clinical success. However, recent advances in areas such antigen identification, formulation development and manufacturing, combination therapy regimens, and indication and patient selection hold promise to reinvigorate the field. Here, we provide a timely update on the clinical status of cancer vaccines. We identify and critically analyze 360 active trials of cancer vaccines according to delivery vehicle, antigen type, indication, and other metrics, as well as highlight eight globally approved products. Finally, we discuss current limitations and future applications for clinical translation of cancer vaccines.

Epidemiology, Molecular Pathogenesis, Immuno-Pathogenesis, Immune Escape Mechanisms and Vaccine Evaluation for HPV-Associated Carcinogenesis

Human papillomavirus (HPV) is implicated in over 90% of cervical cancer cases, with factors like regional variability, HPV genotype, the population studied, HPV vaccination status, and anatomical sample collection location influencing the prevalence and pathology of HPV-induced cancer. HPV-16 and -18 are mainly responsible for the progression of several cancers, including cervix, anus, vagina, penis, vulva, and oropharynx. The oncogenic ability of HPV is not only sufficient for the progression of malignancy, but also for other tumor-generating steps required for the production of invasive cancer, such as coinfection with other viruses, lifestyle factors such as high parity, smoking, tobacco chewing, use of contraceptives for a long time, and immune responses such as stimulation of chronic stromal inflammation and immune deviation in the tumor microenvironment. Viral evasion from immunosurveillance also supports viral persistence, and virus-like particle-based prophylactic vaccines have been licensed, which are effective against high-risk HPV types. In addition, vaccination awareness programs and preventive strategies could help reduce the rate and incidence of HPV infection. In this review, we emphasize HPV infection and its role in cancer progression, molecular and immunopathogenesis, host immune response, immune evasion by HPV, vaccination, and preventive schemes battling HPV infection and HPV-related cancers.

Recent advances and applications of peptide-agent conjugates for targeting tumor cells

BACKGROUND

Cancer, being a complex disease, presents a major challenge for the scientific and medical communities. Peptide therapeutics have played a significant role in different medical practices, including cancer treatment.

METHOD

This review provides an overview of the current situation and potential development prospects of anticancer peptides (ACPs), with a particular focus on peptide vaccines and peptide-drug conjugates for cancer treatment.

RESULTS

ACPs can be used directly as cytotoxic agents (molecularly targeted peptides) or can act as carriers (guiding missile) of chemotherapeutic agents and radionuclides by specifically targeting cancer cells. More than 60 natural and synthetic cationic peptides are approved in the USA and other major markets for the treatment of cancer and other diseases. Compared to traditional cancer treatments, peptides exhibit anticancer activity with high specificity and the ability to rapidly kill target cancer cells. ACP's target and kill cancer cells via different mechanisms, including membrane disruption, pore formation, induction of apoptosis, necrosis, autophagy, and regulation of the immune system. Modified peptides have been developed as carriers for drugs, vaccines, and peptide-drug conjugates, which have been evaluated in various phases of clinical trials for the treatment of different types of solid and leukemia cancer.

CONCLUSIONS

This review highlights the potential of ACPs as a promising therapeutic option for cancer treatment, particularly through the use of peptide vaccines and peptide-drug conjugates. Despite the limitations of peptides, such as poor metabolic stability and low bioavailability, modified peptides show promise in addressing these challenges. Various mechanism of action of anticancer peptides. Modes of action against cancer cells including: inducing apoptosis by cytochrome c release, direct cell membrane lysis (necrosis), inhibiting angiogenesis, inducing autophagy-mediated cell death and immune cell regulation.

Peptide-Decorated Degradable Polycarbonate Nanogels for Eliciting Antigen-Specific Immune Responses

For successful therapeutic interventions in cancer immunotherapy, strong antigen-specific immune responses are required. To this end, immunostimulating cues must be combined with antigens to simultaneously arrive at antigen-presenting cells and initiate cellular immune responses. Recently, imidazoquinolines have shown their vast potential as small molecular Toll-like receptor 7/8 (TLR7/8) agonists for immunostimulation when delivered by nanocarriers. At the same time, peptide antigens are promising antigen candidates but require combination with immune-stimulating adjuvants to boost their immunogenicity and exploit their full potential. Consequently, we herein present biodegradable polycarbonate nanogels as versatile delivery system for adjuvants within the particles' core as well as for peptide antigens by surface decoration. For that purpose, orthogonally addressable multifunctional polycarbonate block copolymers were synthesized, enabling adjuvant conjugation through reactive ester chemistry and peptide decoration by strain-promoted alkyne-azide cycloaddition (SPAAC). In preparation for SPAAC, CD4+-specific peptide sequences of the model protein antigen ovalbumin were equipped with DBCO-moieties by site-selective modification at their N-terminal cysteine. With their azide groups exposed on their surface, the adjuvant-loaded nanogels were then efficiently decorated with DBCO-functional CD4+-peptides by SPAAC. In vitro evaluation of the adjuvant-loaded peptide-decorated gels then confirmed their strong immunostimulating properties as well as their high biocompatibility. Despite their covalent conjugation, the CD4+-peptide-decorated nanogels led to maturation of primary antigen-presenting cells and the downstream priming of CD4+-T cells. Subsequently, the peptide-decorated nanogels loaded with TLR7/8 agonist were successfully processed by antigen-presenting cells, enabling potent immune responses for future application in antigen-specific cancer immunotherapy.

Improving the efficacy of peptide vaccines in cancer immunotherapy

Peptide vaccines have shown great potential in cancer immunotherapy by targeting tumor antigens and activating the patient's immune system to mount a specific response against cancer cells. However, the efficacy of peptide vaccines in inducing a sustained immune response and achieving clinical benefit remains a major challenge. In this review, we discuss the current status of peptide vaccines in cancer immunotherapy and strategies to improve their efficacy. We summarize the recent advancements in the development of peptide vaccines in pre-clinical and clinical settings, including the use of novel adjuvants, neoantigens, nano-delivery systems, and combination therapies. We also highlight the importance of personalized cancer vaccines, which consider the unique genetic and immunological profiles of individual patients. We also discuss the strategies to enhance the immunogenicity of peptide vaccines such as multivalent peptides, conjugated peptides, fusion proteins, and self-assembled peptides. Although, peptide vaccines alone are weak immunogens, combining peptide vaccines with other immunotherapeutic approaches and developing novel approaches such as personalized vaccines can be promising methods to significantly enhance their efficacy and improve the clinical outcomes for cancer patients.

The use of RNA-based treatments in the field of cancer immunotherapy

Over the past several decades, mRNA vaccines have evolved from a theoretical concept to a clinical reality. These vaccines offer several advantages over traditional vaccine techniques, including their high potency, rapid development, low-cost manufacturing, and safe administration. However, until recently, concerns over the instability and inefficient distribution of mRNA in vivo have limited their utility. Fortunately, recent technological advancements have mostly resolved these concerns, resulting in the development of numerous mRNA vaccination platforms for infectious diseases and various types of cancer. These platforms have shown promising outcomes in both animal models and humans. This study highlights the potential of mRNA vaccines as a promising alternative approach to conventional vaccine techniques and cancer treatment. This review article aims to provide a thorough and detailed examination of mRNA vaccines, including their mechanisms of action and potential applications in cancer immunotherapy. Additionally, the article will analyze the current state of mRNA vaccine technology and highlight future directions for the development and implementation of this promising vaccine platform as a mainstream therapeutic option. The review will also discuss potential challenges and limitations of mRNA vaccines, such as their stability and in vivo distribution, and suggest ways to overcome these issues. By providing a comprehensive overview and critical analysis of mRNA vaccines, this review aims to contribute to the advancement of this innovative approach to cancer treatment.

Vaccines in Breast Cancer: Challenges and Breakthroughs

Breast cancer is a problem for women's health globally. Early detection techniques come in a variety of forms ranging from local to systemic and from non-invasive to invasive. The treatment of cancer has always been challenging despite the availability of a wide range of therapeutics. This is either due to the variable behaviour and heterogeneity of the proliferating cells and/or the individual's response towards the treatment applied. However, advancements in cancer biology and scientific technology have changed the course of the cancer treatment approach. This current review briefly encompasses the diagnostics, the latest and most recent breakthrough strategies and challenges, and the limitations in fighting breast cancer, emphasising the development of breast cancer vaccines. It also includes the filed/granted patents referring to the same aspects.

The Current Status, Challenges, and Future Potential of Therapeutic Vaccination in Glioblastoma

Glioblastoma (GBM) is the most common malignant primary brain tumor and confers a dismal prognosis. With only two FDA-approved therapeutics showing modest survival gains since 2005, there is a great need for the development of other disease-targeted therapies. Due, in part, to the profound immunosuppressive microenvironment seen in GBMs, there has been a broad interest in immunotherapy. In both GBMs and other cancers, therapeutic vaccines have generally yielded limited efficacy, despite their theoretical basis. However, recent results from the DCVax-L trial provide some promise for vaccine therapy in GBMs. There is also the potential that future combination therapies with vaccines and adjuvant immunomodulating agents may greatly enhance antitumor immune responses. Clinicians must remain open to novel therapeutic strategies, such as vaccinations, and carefully await the results of ongoing and future trials. In this review of GBM management, the promise and challenges of immunotherapy with a focus on therapeutic vaccinations are discussed. Additionally, adjuvant therapies, logistical considerations, and future directions are discussed.

Therapeutic Cancer Vaccines and Their Future Implications

The continuous progress in vaccine development witnessed in the last decades, culminated with the development of vaccines against cancers, is set to change how various cancers are treated [...]

Nanovaccines for cancer immunotherapy: Focusing on complex formation between adjuvant and antigen

As an interesting cancer immunotherapy approach, cancer vaccines have been developed to deliver tumor antigens and adjuvants to antigen-presenting cells (APCs). Although the safety and easy production shifted the vaccine designing platforms toward the subunit vaccines, their efficacy is limited due to inefficient vaccine delivery. Nanotechnology-based vaccines, called nanovaccines, address the delivery limitations through co-delivery of antigens and adjuvants into lymphoid organs and APCs and their intracellular release, leading to cross-presentation of antigens and induction of potent anti-tumor immune responses. Although the nanovaccines, either as encapsulating agents or biomimetic nanoparticles, exert the desired anti-tumor activities, there is evidence that the mixing formulation to form nanocomplexes between antigens and adjuvants based on the electrostatic interactions provokes high levels of immune responses owing to Ags' availability and faster release. Here, we summarized the various platforms for developing cancer vaccines and the advantages of using delivery systems. The cancer nanovaccines, including nanoparticle-based and biomimetic-based nanovaccines, are discussed in detail. Finally, we focused on the nanocomplexes formation between antigens and adjuvants as promising cancer nanovaccine platforms.

Peptide Vaccines in Melanoma: Chemical Approaches towards Improved Immunotherapeutic Efficacy

Cancer of the skin is by far the most common of all cancers. Although the incidence of melanoma is relatively low among skin cancers, it can account for a high number of skin cancer deaths. Since the start of deeper insight into the mechanisms of melanoma tumorigenesis and their strong interaction with the immune system, the development of new therapeutical strategies has been continuously rising. The high number of melanoma cell mutations provides a diverse set of antigens that the immune system can recognize and use to distinguish tumor cells from normal cells. Peptide-based synthetic anti-tumor vaccines are based on tumor antigens that elicit an immune response due to antigen-presenting cells (APCs). Although targeting APCs with peptide antigens is the most important assumption for vaccine development, peptide antigens alone are poorly immunogenic. The immunogenicity of peptide antigens can be improved not only by synthetic modifications but also by the assistance of adjuvants and/or delivery systems. The current review summarizes the different chemical approaches for the development of effective peptide-based vaccines for the immunotherapeutic treatment of advanced melanoma.

Neoantigens: promising targets for cancer therapy

Recent advances in neoantigen research have accelerated the development and regulatory approval of tumor immunotherapies, including cancer vaccines, adoptive cell therapy and antibody-based therapies, especially for solid tumors. Neoantigens are newly formed antigens generated by tumor cells as a result of various tumor-specific alterations, such as genomic mutation, dysregulated RNA splicing, disordered post-translational modification, and integrated viral open reading frames. Neoantigens are recognized as non-self and trigger an immune response that is not subject to central and peripheral tolerance. The quick identification and prediction of tumor-specific neoantigens have been made possible by the advanced development of next-generation sequencing and bioinformatic technologies. Compared to tumor-associated antigens, the highly immunogenic and tumor-specific neoantigens provide emerging targets for personalized cancer immunotherapies, and serve as prospective predictors for tumor survival prognosis and immune checkpoint blockade responses. The development of cancer therapies will be aided by understanding the mechanism underlying neoantigen-induced anti-tumor immune response and by streamlining the process of neoantigen-based immunotherapies. This review provides an overview on the identification and characterization of neoantigens and outlines the clinical applications of prospective immunotherapeutic strategies based on neoantigens. We also explore their current status, inherent challenges, and clinical translation potential.

Combination of STING and TLR 7/8 Agonists as Vaccine Adjuvants for Cancer Immunotherapy

Immunostimulatory adjuvants that potently activate antigen-presenting cells and (in turn) prime cytotoxic T cells are a key component of anticancer vaccines. In this study, we investigated a multi-adjuvant approach combining a TLR 7/8 agonist (522) and a STING agonist (DMXAA) to promote enhanced antigen cross-presentation, stimulate specific antitumor T-cell responses, and provide improved anticancer efficacy. In vitro experiments using bone marrow-derived dendritic cells (BMDCs) confirmed enhanced activation with the 522-DMXAA combination based on both co-stimulatory molecule expression and pro-inflammatory cytokine secretion. The immunization of mice with vaccines comprising both 522 and DMXAA resulted in greater antitumor efficacy in B16F10 melanoma and MB49 bladder tumor models relative to mono-agonist vaccines. Flow cytometry-based analysis of immune cells from immunized mice revealed the significant activation of antigen-presenting cells, increased numbers of activated and Ag-specific CD8+ T cells in the spleen and lymph nodes, modest NK cell activation, and an overall reduction in CD206⁺ macrophages. These results were supported by an increase in the levels of IFN-γ and a reduction in IL-10 levels in the sera. Taken together, these findings demonstrate the potential of the TLR7/8 and STING agonist combination as vaccine adjuvants to activate both innate and adaptive immune responses.

Chemical and Synthetic Biology Approaches for Cancer Vaccine Development

Cancer vaccines have been considered promising therapeutic strategies and are often constructed from whole cells, attenuated pathogens, carbohydrates, peptides, nucleic acids, etc. However, the use of whole organisms or pathogens can elicit unwanted immune responses arising from unforeseen reactions to the vaccine components. On the other hand, synthetic vaccines, which contain antigens that are conjugated, often with carrier proteins, can overcome these issues. Therefore, in this review we have highlighted the synthetic approaches and discussed several bioconjugation strategies for developing antigen-based cancer vaccines. In addition, the major synthetic biology approaches that were used to develop genetically modified cancer vaccines and their progress in clinical research are summarized here. Furthermore, to boost the immune responses of any vaccines, the addition of suitable adjuvants and a proper delivery system are essential. Hence, this review also mentions the synthesis of adjuvants and utilization of biomaterial scaffolds, which may facilitate the design of future cancer vaccines.

Advances in Nanotechnology for Cancer Immunoprevention and Immunotherapy: A Review

One of the most effective cancer therapies, cancer immunotherapy has produced outstanding outcomes in the field of cancer treatment. However, the cost is excessive, which limits its applicability. A smart way to address this issue would be to apply the knowledge gained through immunotherapy to develop strategies for the immunoprevention of cancer. The use of cancer vaccines is one of the most popular methods of immunoprevention. This paper reviews the technologies and processes that support the advantages of cancer immunoprevention over traditional cancer immunotherapies. Nanoparticle drug delivery systems and nanoparticle-based nano-vaccines have been employed in the past for cancer immunotherapy. This paper outlines numerous immunoprevention strategies and how nanotechnology can be applied in immunoprevention. To comprehend the non-clinical and clinical evaluation of these cancer vaccines through clinical studies is essential for acceptance of the vaccines.

Peptide emulsions in incomplete Freund's adjuvant create effective nurseries promoting egress of systemic CD4+ and CD8+ T cells for immunotherapy of cancer

Water-in-oil emulsion incomplete Freund's adjuvant (IFA) has been used as an adjuvant in preventive and therapeutic vaccines since its development. New generation, highly purified modulations of the adjuvant, Montanide incomplete seppic adjuvant (ISA)-51 and Montanide ISA-720, were developed to reduce toxicity. Montanide adjuvants are generally considered to be safe, with adverse events largely consisting of antigen and adjuvant dose-dependent injection site reactions (ISRs). Peptide vaccines in Montanide ISA-51 or ISA-720 are capable of inducing both high antibody titers and durable effector T cell responses. However, an efficient T cell response depends on the affinity of the peptide to the presenting major histocompatibility complex class I molecule, CD4⁺ T cell help and/or the level of co-stimulation. In fact, in the therapeutic cancer vaccine setting, presence of a CD4⁺ T cell epitope seems crucial to elicit a robust and durable systemic T cell response. Additional inclusion of a Toll-like receptor ligand can further increase the magnitude and durability of the response. Use of extended peptides that need a processing step only accomplished effectively by dendritic cells (DCs) can help to avoid antigen presentation by nucleated cells other than DC. Based on recent clinical trial results, therapeutic peptide-based cancer vaccines using emulsions in adjuvant Montanide ISA-51 can elicit robust antitumor immune responses, provided that sufficient tumor-specific CD4⁺ T cell help is given in addition to CD8⁺ T cell epitopes. Co-treatment with PD-1 T cell checkpoint inhibitor, chemotherapy or other immunomodulatory drugs may address local and systemic immunosuppressive mechanisms, and further enhance efficacy of therapeutic cancer peptide vaccines in IFA and its modern variants. Blinded randomized placebo-controlled trials are critical to definitively prove clinical efficacy. Mineral oil-based adjuvants for preventive vaccines, to tackle spread and severity of infectious disease, induce immune responses, but require more studies to reduce toxicity.

Poly(hydrophobic Amino Acids) and Liposomes for Delivery of Vaccine against Group A Streptococcus

Adjuvants and delivery systems are essential components of vaccines to increase immunogenicity against target antigens, particularly for peptide epitopes (poor immunogens). Emulsions, nanoparticles, and liposomes are commonly used as a delivery system for peptide-based vaccines. A Poly(hydrophobic amino acids) delivery system was previously conjugated to Group A Streptococcus (GAS)-derived peptide epitopes, allowing the conjugates to self-assemble into nanoparticles with self adjuvanting ability. Their hydrophobic amino acid tail also serves as an anchoring moiety for the peptide epitope, enabling it to be integrated into the liposome bilayer, to further boost the immunological responses. Polyleucine-based conjugates were anchored to cationic liposomes using the film hydration method and administered to mice subcutaneously. The polyleucine-peptide conjugate, its liposomal formulation, and simple liposomal encapsulation of GAS peptide epitope induced mucosal (saliva IgG) and systemic (serum IgG, IgG1 and IgG2c) immunity in mice. Polyleucine acted as a potent liposome anchoring portion, which stimulated the production of highly opsonic antibodies. The absence of polyleucine in the liposomal formulation (encapsulated GAS peptide) induced high levels of antibody titers, but with poor opsonic ability against GAS bacteria. However, the liposomal formulation of the conjugated vaccine was no more effective than conjugates alone self-assembled into nanoparticles.

Cancer vaccines as promising immuno-therapeutics: platforms and current progress

Research on tumor immunotherapy has made tremendous progress in the past decades, with numerous studies entering the clinical evaluation. The cancer vaccine is considered a promising therapeutic strategy in the immunotherapy of solid tumors. Cancer vaccine stimulates anti-tumor immunity with tumor antigens, which could be delivered in the form of whole cells, peptides, nucleic acids, etc. Ideal cancer vaccines could overcome the immune suppression in tumors and induce both humoral immunity and cellular immunity. In this review, we introduced the working mechanism of cancer vaccines and summarized four platforms for cancer vaccine development. We also highlighted the clinical research progress of the cancer vaccines, especially focusing on their clinical application and therapeutic efficacy, which might hopefully facilitate the future design of the cancer vaccine.

Peptide-Based Nanovaccines in the Treatment of Cervical Cancer: A Review of Recent Advances

Persistent infection with high-risk human papillomaviruses (HPVs), such as HPV-16 and HPV-18, can induce cervical cancer in humans. The disease carries high morbidity and mortality among females worldwide. Inoculation with prophylactic HPV vaccines, such as Gardasil^® or Cervarix^®, is the predominant method of preventing cervical cancer in females 6 to 26 years of age. However, despite the availability of commercial prophylactic HPV vaccines, no therapeutic HPV vaccines to eliminate existing HPV infections have been approved. Peptide-based vaccines, which form one of the most potent vaccine platforms, have been broadly investigated to overcome this shortcoming. Peptide-based vaccines are especially effective in inducing cellular immune responses and eradicating tumor cells when combined with nanoscale adjuvant particles and delivery systems. This review summarizes progress in the development of peptide-based nanovaccines against HPV infection.

Induction of Peptide-specific CTL Activity and Inhibition of Tumor Growth Following Immunization with Nanoparticles Coated with Tumor Peptide-MHC-I Complexes

Tumor peptides associated with MHC class I molecules or their synthetic variants have attracted great attention for their potential use as vaccines to induce tumor-specific CTLs. However, the outcome of clinical trials of peptide-based tumor vaccines has been disappointing. There are various reasons for this lack of success, such as difficulties in delivering the peptides specifically to professional Ag-presenting cells, short peptide half-life in vivo, and limited peptide immunogenicity. We report here a novel peptide vaccination strategy that efficiently induces peptide-specific CTLs. Nanoparticles (NPs) were fabricated from a biodegradable polymer, poly(D,L-lactic-co-glycolic acid), attached to H-2K^b molecules, and then the natural peptide epitopes associated with the H-2K^b molecules were exchanged with a model tumor peptide, SIINFEKL (OVA_257-268). These NPs were efficiently phagocytosed by immature dendritic cells (DCs), inducing DC maturation and activation. In addition, the DCs that phagocytosed SIINFEKL-pulsed NPs potently activated SIINFEKL-H-2K^b complex-specific CD8⁺ T cells via cross-presentation of SIINFEKL. In vivo studies showed that intravenous administration of SIINFEKL-pulsed NPs effectively generated SIINFEKL-specific CD8⁺ T cells in both normal and tumor-bearing mice. Furthermore, intravenous administration of SIINFEKL-pulsed NPs into EG7.OVA tumor-bearing mice almost completely inhibited the tumor growth. These results demonstrate that vaccination with polymeric NPs coated with tumor peptide-MHC-I complexes is a novel strategy for efficient induction of tumor-specific CTLs.

Cry1Ac Protoxin Confers Antitumor Adjuvant Effect in a Triple-Negative Breast Cancer Mouse Model by Improving Tumor Immunity

The Cry1Ac protoxin from Bacillus thuringiensis is a systemic and mucosal adjuvant, able to confer protective immunity in different infection murine models and induce both Th1 and TCD8+ cytotoxic lymphocyte responses, which are required to induce antitumor immunity. The Cry1Ac toxin, despite having not being characterized as an adjuvant, has also proved to be immunogenic and able to activate macrophages. Here, we investigated the potential antitumor adjuvant effect conferred by the Cry1Ac protoxin and Cry1Ac toxin in a triple negative breast cancer (TNBC) murine model. First, we evaluated the ability of Cry1Ac proteins to improve dendritic cell (DC) activation and cellular response through intraperitoneal (i.p.) coadministration with the 4T1 cellular lysate. Mice coadministered with the Cry1Ac protoxin showed an increase in the number and activation of CD11c+MHCII- and CD11c+MHCII+^low in the peritoneal cavity and an increase in DC activation (CD11c+MHCII+) in the spleen. Cry1Ac protoxin increased the proliferation of TCD4+ and TCD8+ lymphocytes in the spleen and mesenteric lymph nodes (MLN), while the Cry1Ac toxin only increased the proliferation of TCD4+ and TCD8+ in the MLN. Remarkably, when tested in the in vivo TNBC mouse model, prophylactic immunizations with 4T1 lysates plus the Cry1Ac protoxin protected mice from developing tumors. The antitumor effect conferred by the Cry1Ac protoxin also increased specific cytotoxic T cell responses, and prevented the typical tumor-related decrease of T cells (TCD3+ and TCD4+) as well the increase of myeloid-derived suppressor cells (MDSC) in spleen. Also in the tumor microenvironment of mice coadministered twice with Cry1Ac protoxin immunological improvements were found such as reductions in immunosupressive populations (T regulatory lymphocytes and MDSC) along with increases in macrophages upregulating CD86. These results show a differential antitumor adjuvant capability of Cry1Ac proteins, highlighting the ability of Cry1Ac protoxin to enhance local and systemic tumor immunity in TNBC. Finally, using a therapeutic approach, we evaluated the coadministration of Cry1Ac protoxin with doxorubicin. A significant reduction in tumor volume and lung metastasis was found, with increased intratumoral levels of tumor necrosis factor-α and IL-6 with respect to the vehicle group, further supporting its antitumor applicability.

S-540956, a CpG Oligonucleotide Annealed to a Complementary Strand With an Amphiphilic Chain Unit, Acts as a Potent Cancer Vaccine Adjuvant by Targeting Draining Lymph Nodes

Robust induction of cancer-antigen-specific CD8⁺ T cells is essential for the success of cancer peptide vaccines, which are composed of a peptide derived from a cancer-specific antigen and an immune-potentiating adjuvant, such as a Toll-like receptor (TLR) agonist. Efficient delivery of a vaccine antigen and an adjuvant to antigen-presenting cells in the draining lymph nodes (LNs) holds key to maximize vaccine efficacy. Here, we developed S-540956, a novel TLR9-agonistic adjuvant consisting of B-type CpG ODN2006 (also known as CpG7909), annealed to its complementary sequence oligodeoxynucleotide (ODN) conjugated to a lipid; it could target both a cancer peptide antigen and a CpG-adjuvant in the draining LNs. S-540956 accumulation in the draining LNs and activation of plasmacytoid dendritic cells (pDCs) were significantly higher than that of ODN2006. Mechanistic analysis revealed that S-540956 enhanced the induction of MHC class I peptide-specific CD8⁺ T cell responses via TLR9 in a CD4⁺ T cell-independent manner. In mice, the therapeutic effect of S-540956-adjuvanted with a human papillomavirus (HPV)-E7 peptide vaccine against HPV-E7-expressing TC-1 tumors was significantly better than that of an ODN2006-adjuvanted vaccine. Our findings demonstrate a novel adjuvant discovery with the complementary strand conjugated to a lipid, which enabled draining LN targeting and increased ODN2006 accumulation in draining LNs, thereby enhancing the adjuvant effect. Our findings imply that S-540956 is a promising adjuvant for cancer peptide vaccines and has a high potential for applications in various vaccines, including recombinant protein vaccines.

Combination of Photodynamic Therapy and Therapeutic Vaccination

Tumor ablation by photodynamic therapy (PDT) results in a strong reduction in tumor mass and can lead to improved recognition of tumor cells by the immune system. This supports combinations of PDT and immunotherapy for the treatment of advanced tumors. Therapeutic vaccination is a tumor-specific type of cancer immunotherapy that aims to directly strengthen the immune response against tumor antigens. In this chapter, we describe the combination of PDT and therapeutic vaccination using a peptide tumor antigen vaccine.

Telomeres and Cancer

Telomeres cap the ends of eukaryotic chromosomes and are indispensable chromatin structures for genome protection and replication. Telomere length maintenance has been attributed to several functional modulators, including telomerase, the shelterin complex, and the CST complex, synergizing with DNA replication, repair, and the RNA metabolism pathway components. As dysfunctional telomere maintenance and telomerase activation are associated with several human diseases, including cancer, the molecular mechanisms behind telomere length regulation and protection need particular emphasis. Cancer cells exhibit telomerase activation, enabling replicative immortality. Telomerase reverse transcriptase (TERT) activation is involved in cancer development through diverse activities other than mediating telomere elongation. This review describes the telomere functions, the role of functional modulators, the implications in cancer development, and the future therapeutic opportunities.

Heterologous administration of HPV16 E7 epitope-loaded nanocomplexes inhibits tumor growth in mouse model

The nanostructured complexes can result in enhanced vaccine efficacy by facilitating the distribution and uptake of antigens by antigen-presenting cells (APCs), thereby stimulating immune responses. Here, we hypothesized that either directly coating of nanoadjuvants including aluminum phosphate (AlPO₄) and adenovirus (Ad) with a modified HPV16 E7 MHC-I specific epitope, RAHYNIVTF_49-57, or mixing the CpG oligodeoxynucleotide (CpG-ODN) with the cationic epitope to form nanocomlexes, and their combinational therapy would enhance their anti-tumor effects in a TC-1 mouse model. The positively-charged HPV16 E7 epitope was attracted to the oppositely-charged adjuvants by electrostatic interaction to generate epitope/adjuvant nanocomplexes. We showed that coating the nanosized adjuvants with the cationic epitope increased the particles' surface charge without significant change in their size. We then tested the cellular immunogenicity and therapeutic efficacy of nanocomplexes by measuring IL-10 and IFN-γ production, the expression of CD107a as a marker of CTL response, and tumor growth inhibition. The nanocomplexes were administered either in homologous or heterologous prime-boost regimens, and heterologous immunizations including Ad/Pep-CpG/Pep, CpG/Pep-Ad/Pep, Ad/Pep-Alum/Pep, and Alum/Pep-Ad/Pep induced significantly higher levels of IL-10, IFN-γ, and CD107a-expressing CD8 T cells compared with homologous administrations. Furthermore, the tumor growth was significantly suppressed in mice receiving nanostructured complexes in the heterologous immunizations. Our study highlights the potential of the heterologous prime-boost administration of the epitope-coated nanostructures as an effective immunization strategy.

Delivery of a Cancer-Testis Antigen-Derived Peptide Using Conformationally Restricted Dipeptide-Based Self-Assembled Nanotubes

Use of tumor-associated antigens for cancer immunotherapy is limited due to their poor in vivo stability and low cellular uptake. Delivery of antigenic peptides using synthetic polymer-based nanostructures has been actively pursued but with limited success. Peptide-based nanostructures hold much promise as delivery vehicles due to their easy design and synthesis and inherent biocompatibility. Here, we report self-assembly of a dipeptide containing a non-natural amino acid, α,β-dehydrophenylalanine (ΔF), into nanotubes, which efficiently entrapped a MAGE-3-derived peptide (M3). M3 entrapped in F-ΔF nanotubes was more stable to a nonspecific protease treatment and both F-ΔF and F-ΔF-M3 showed no cellular toxicity for four cancerous and noncancerous cell lines used. F-ΔF-M3 showed significantly higher cellular uptake in RAW 267.4 macrophage cells compared to M3 alone and also induced in vitro maturation of dendritic cells (DCs). Immunization of mice with F-ΔF-M3 selected a higher number of IFN-γ secreting CD8⁺ T cells and CD4⁺ T compared to M3 alone. On day 21, a tumor growth inhibition ratio (TGI, %) of 41% was observed in a murine melanoma model. These results indicate that F-ΔF nanotubes are highly biocompatible, efficiently delivered M3 to generate cytotoxic T lymphocytes responses, and able to protect M3 from degradation under in vivo conditions. The F-ΔF dipeptide-based nanotubes may be considered as a good platform for further development as delivery agents.

Physiopathology and effectiveness of therapeutic vaccines against human papillomavirus

Human papillomavirus (HPV) is a well-known sexually transmitted disorder globally. Human papillomavirus (HPV) is the 3rd most common cancer that causes cervical carcinoma, and globally it accounts for 275,000 deaths every year. The load of HPV-associated abrasions can be lessened through vaccination. At present, three forms of prophylactic vaccines, Cervarix, Gadrasil, and Gardasil 9, are commercially accessible but all these prophylactic vaccines have not the ability to manage and control developed abrasions or infections. Therefore, a considerable amount of the population is not secured from HPV infectivity. Consequently, the development of therapeutic HPV vaccines is a crucial requirement of this era, for the treatment of persisting infections, and to stop the progression of HPV-associated cancers. Therapeutic vaccines are a developing trial approach. Because of the constitutive expression of E6 and E7 early genes in cancerous and pre-cancerous tissues, and their involvement in disturbance of the cell cycle, these are best targets for this therapeutic vaccine treatment. For the synthesis and development of therapeutic vaccines, various approaches have been examined comprising cell-based vaccines, peptide/protein-based vaccines, nucleic acid-based vaccines, and live-vector vaccines all proceeding towards clinical trials. This review emphasizes the development, progress, current status, and future perspective of several vaccines for the cure of HPV-related abrasions and cancers. This review also provides an insight to assess the effectiveness, safety, efficacy, and immunogenicity of therapeutic vaccines in the cure of patients infected with HPV-associated cervical cancer.

Pancreatic Cancer and Immunotherapy: A Clinical Overview

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with high mortality. The vast majority of patients present with unresectable, advanced stage disease, for whom standard of care chemo(radio)therapy may improve survival by several months. Immunotherapy has led to a fundamental shift in the treatment of several advanced cancers. However, its efficacy in PDAC in terms of clinical benefit is limited, possibly owing to the immunosuppressive, inaccessible tumor microenvironment. Still, various immunotherapies have demonstrated the capacity to initiate local and systemic immune responses, suggesting an immune potentiating effect. In this review, we address PDAC's immunosuppressive tumor microenvironment and immune evasion methods and discuss a wide range of immunotherapies, including immunomodulators (i.e., immune checkpoint inhibitors, immune stimulatory agonists, cytokines and adjuvants), oncolytic viruses, adoptive cell therapies (i.e., T cells and natural killer cells) and cancer vaccines. We provide a general introduction to their working mechanism as well as evidence of their clinical efficacy and immune potentiating abilities in PDAC. The key to successful implementation of immunotherapy in this disease may rely on exploitation of synergistic effects between treatment combinations. Accordingly, future treatment approaches should aim to incorporate diverse and novel immunotherapeutic strategies coupled with cytotoxic drugs and/or local ablative treatment, targeting a wide array of tumor-induced immune escape mechanisms.

[Tumor vaccination-strategies and time points]

BACKGROUND

Immunotherapies have gained increasing importance in the treatment of cancer in recent years. This also includes tumor vaccines, which are used therapeutically to direct the immune system specifically against tumor cells.

OBJECTIVES

Different strategies of tumor vaccination, their current state of development, the optimal timing and possible combinations of cancer vaccines in the treatment of cancer are discussed.

METHODS

Scientific publications on various tumor vaccination strategies based on ongoing studies that are listed on clinicaltrials.gov are summarized.

CONCLUSIONS

For effective tumor vaccination, the selection of suitable tumor antigens present on the cell surface via human leukocyte antigen (HLA) molecules is essential. Suitable antigens should be present exclusively on tumor cells and able to induce a specific anti-tumor immune response, i.e. activate cytotoxic and T helper cells. For this purpose, neoepitopes derived from tumor-specific mutations or tumor-associated antigens (TAAs), which are present exclusively in tumor tissue due to altered gene expression or processing, can be used. For the application of the antigens, various strategies combined with suitable adjuvants are available, including peptide vaccines, DNA- or RNA-based vaccines, approaches with dendritic cells or whole tumor cell vaccines. Currently, numerous vaccination approaches as well as combination protocols are being evaluated in clinical trials with the aim to establish specific and low side effect immunotherapies to combat malignancies and enable long-term protection from disease recurrence via the induction of long-lasting antitumor immune responses.

Tumor targeting nanoparticle E749-57-HSP110-RGD elicits potent anti-tumor immune response in a CD8-dependent manner in cervical cancer-bearing mouse model

Our previous research verified that HSP (heat shock protein) 110 could enhance the anti-tumor effect of HPV16 E7_49-57 epitope. In this study, to optimize the immunotherapy of this vaccine type, we developed and evaluated the anti-tumor immunity of a nanoparticle vaccine format assembling with E7_49-57-HSP110 fusion expression plasmid and RGD-GGG-K₁₈ polypeptide. The nanoparticle vaccine was self-assembled from positively charged RGD-GGG-K₁₈ polypeptide and negatively charged fusion expression plasmid pIRES2-3× E7-HSP110-EGFP. The particle size, stability, expression of E7_49-57-HSP110 fusion protein and the target ability of nanoparticle were determined, respectively. Specific CTL responses were determined by E7 tetramer staining and cytotoxicity assay in TC-1 tumor-bearing mice (CD4/CD8 knockout). The preventive and therapeutic experiments of nanoparticle vaccine were investigated in TC-1 tumor-bearing mice. Results showed that the RGD-GGG-K₁₈ polypeptide and pIRES2-3× E7-HSP110-EGFP plasmid self-assembled nanoparticles about 100 nanometers in diameter when the charge ratios of peptide/plasmid were 2. The nanoparticles effectively entered TC-1 cells directed by RGD target-peptide, and correctly expressed the E7-HSP110 fusion protein. The HSP110 effectively facilitated nanoparticles activating CD8⁺T cells than nanoparticles without HSP110, including the CD8⁺ T cell number and the IFN-γ level; in contrast, the CD4⁺T cells immune response remained indiscriminate among the mice groups. This nanoparticle formulation inhibited tumor growth and prolonged the survival duration in the prophylactic and therapeutic mouse models. Therefore, the RGD-based tumor-targeting nanoparticle expressing E7_49-57-HSP110 fusion protein can efficiently evoke anti-tumor activity and thus suggests it might be a favorable candidate for cervical cancer immunotherapy.

Bursal peptide BP-IV as a novel immunoadjuvant enhances the protective efficacy of an epitope peptide vaccine containing T and B cell epitopes of the H9N2 avian influenza virus

Short peptide antigens covering conserved T or B cell epitopes have been investigated in influenza vaccines. Bursal pentapeptide V (BPP-V) and bursal peptide IV (BP-IV) are small molecular peptides that were isolated and identified from the bursa of Fabricius (BF) and induce a strong immune response at both the humoural and cellular levels. To explore the molecular adjuvant potential of BPP-V and BP-IV with an epitope vaccine, an epitope peptide (HA_284-298, GNCVVQCQTERGGLN) rich in T and B cell epitopes for the H9N2 avian influenza virus (AIV) haemagglutinin (HA) protein was selected. BPP-V and BP-IV were coupled with the epitope peptide sequence to form BPP-V and BP-IV-epitope vaccines, respectively. The immunoefficacy of BPP-V and BP-IV-epitope peptide vaccines was evaluated. The results showed that the epitope peptide had weak immunogenicity. The BPP-V-epitope peptide vaccine promoted only the secretion of anti-HA IgG and IgG1 antibodies. The BP-IV-epitope peptide vaccine not only promoted the production of anti-HA IgG and IgG1 antibodies but also significantly induced the production of the IgG2a antibody. The BP-IV-epitope peptide vaccine significantly promoted the production of interleukin (IL-4) and interferon-γ (IFN-γ) (the BPP-V epitope peptide vaccine promoted only the production of IL-4), enhanced the cytotoxic T lymphocyte (CTL) response, and increased the proportion of CD3⁺ T lymphocytes. Moreover, the BP-IV-epitope peptide vaccine promoted a cell-mediated immune response similar to that of the AIV vaccine group. Furthermore, BPP-V and BP-IV-epitope peptide vaccines could also accelerate the clearance of pulmonary virus and reduce pathological damage after the challenge with H9N2 AIV. This study demonstrates the potential of BP-IV as an effective adjuvant for the epitope peptide vaccine for the H9N2 AIV.

Beyond Just Peptide Antigens: The Complex World of Peptide-Based Cancer Vaccines

Peptide-based cancer vaccines rely upon the strong activation of the adaptive immune response to elicit its effector function. They have shown to be highly specific and safe, but have yet to prove themselves as an efficacious treatment for cancer in the clinic. This is for a variety of reasons, including tumour heterogeneity, self-tolerance, and immune suppression. Importance has been placed on the overall design of peptide-based cancer vaccines, which have evolved from simple peptide derivatives of a cancer antigen, to complex drugs; incorporating overlapping regions, conjugates, and delivery systems to target and stimulate different components of antigen presenting cells, and to bolster antigen cross-presentation. Peptide-based cancer vaccines are increasingly becoming more personalised to an individual's tumour antigen repertoire and are often combined with existing cancer treatments. This strategy ultimately aids in combating the shortcomings of a more generalised vaccine strategy and provides a comprehensive treatment, taking into consideration cancer cell variability and its ability to avoid immune interrogation.

ImmunoBody®-HAGE derived vaccine induces immunity to HAGE and delays the growth and metastasis of HAGE-expressing tumours in vivo

The management of patients with triple-negative breast cancer (TNBC) continues to pose a significant clinical challenge. Less than 30% of women with metastatic TNBC survive 5 years, despite adjuvant chemotherapy and the initial higher rates of clinical response that can be achieved with neoadjuvant chemotherapy. ImmunoBody® is a plasmid DNA designed to encode a human antibody molecule with complementary determining regions (CDRs) engineered to express cytotoxic and helper T cell epitopes derived from the cancer antigen of interest. HAGE is a Cancer Testis Antigen, which is expressed in TNBC. Herein, we have identified a 30-amino-acid-long HAGE-derived sequence containing HLA-A2 and HLA-DR1 restricted epitopes and demonstrated that the use of this sequence as peptide (with CpG/IFA) or incorporated into an ImmunoBody® vaccine can generate specific IFNγ secreting splenocytes in HHDII/DR1 mice. T-cell responses elicited by the ImmunoBody®-HAGE vaccine were superior to peptide immunisation. Moreover, splenocytes from ImmunoBody®-HAGE vaccinated mice stimulated in vitro could recognise HAGE⁺ tumour cells and the human TNBC cell line MDA-MB-231. More importantly, the growth of implanted B16/HHDII/DR1/HAGE⁺ cells was significantly delayed by the ImmunoBody®-HAGE vaccine in both prophylactic and experimental metastasis settings. Overall, we demonstrate the potential of HAGE-derived vaccines for treating HAGE-expressing cancers and that such vaccines could be considered as therapeutic options for patients with HAGE⁺ TNBC after conventional treatment to prevent disease recurrence.

Making a Cold Tumor Hot: The Role of Vaccines in the Treatment of Glioblastoma

The use of immunotherapies for the treatment of brain tumors is a topic that has garnered considerable excitement in recent years. Discoveries such as the presence of a glymphatic system and immune surveillance in the central nervous system (CNS) have shattered the theory of immune privilege and opened up the possibility of treating CNS malignancies with immunotherapies. However, despite many immunotherapy clinical trials aimed at treating glioblastoma (GBM), very few have demonstrated a significant survival benefit. Several factors for this have been identified, one of which is that GBMs are immunologically "cold," implying that the cancer does not induce a strong T cell response. It is postulated that this is why clinical trials using an immune checkpoint inhibitor alone have not demonstrated efficacy. While it is well established that anti-cancer T cell responses can be facilitated by the presentation of tumor-specific antigens to the immune system, treatment-related death of GBM cells and subsequent release of molecules have not been shown to be sufficient to evoke an anti-tumor immune response effective enough to have a significant impact. To overcome this limitation, vaccines can be used to introduce exogenous antigens at higher concentrations to the immune system to induce strong tumor antigen-specific T cell responses. In this review, we will describe vaccination strategies that are under investigation to treat GBM; categorizing them based on their target antigens, form of antigens, vehicles used, and pairing with specific adjuvants. We will review the concept of vaccine therapy in combination with immune checkpoint inhibitors, as it is hypothesized that this approach may be more effective in overcoming the immunosuppressive milieu of GBM. Clinical trial design and the need for incorporating robust immune monitoring into future studies will also be discussed here. We believe that the integration of evolving technologies of vaccine development, delivery, and immune monitoring will further enhance the role of these therapies and will likely remain an important area of investigation for future treatment strategies for GBM patients.

Dendritic Cell Tumor Vaccination via Fc Gamma Receptor Targeting: Lessons Learned from Pre-Clinical and Translational Studies

Despite significant recent improvements in the field of immunotherapy, cancer remains a heavy burden on patients and healthcare systems. In recent years, immunotherapies have led to remarkable strides in treating certain cancers. However, despite the success of checkpoint inhibitors and the advent of cellular therapies, novel strategies need to be explored to (1) improve treatment in patients where these approaches fail and (2) make such treatments widely and financially accessible. Vaccines based on tumor antigens (Ag) have emerged as an innovative strategy with the potential to address these areas. Here, we review the fundamental aspects relevant for the development of cancer vaccines and the critical role of dendritic cells (DCs) in this process. We first offer a general overview of DC biology and routes of Ag presentation eliciting effective T cell-mediated immune responses. We then present new therapeutic avenues specifically targeting Fc gamma receptors (FcγR) as a means to deliver antigen selectively to DCs and its effects on T-cell activation. We present an overview of the mechanistic aspects of FcγR-mediated DC targeting, as well as potential tumor vaccination strategies based on preclinical and translational studies. In particular, we highlight recent developments in the field of recombinant immune complex-like large molecules and their potential for DC-mediated tumor vaccination in the clinic. These findings go beyond cancer research and may be of relevance for other disease areas that could benefit from FcγR-targeted antigen delivery, such as autoimmunity and infectious diseases.

Towards customized cancer vaccines: a promising filed in personalized cancer medicine

INTRODUCTION

Cancer remains a major source of disease burden worldwide. Although cancer vaccines have been developed, most currently available cancer vaccines have limited therapeutic efficacy. Recent research using novel sequencing and bioinformatic tools has led scientists to realize that each tumor harbors a unique set of genetic mutations that can manifest as tumor-specific neoantigens. Therefore, it would be useful to develop personalized cancer vaccines that target neoantigens, which might improve the efficacy of these cancer treatments.

AREAS COVERED

This review covers cancer vaccine development and the emerging field of personalized cancer vaccines, with a discussion of future clinical trials for this promising treatment strategy.

EXPERT OPINION

Developing vaccines to treat tumors is one of the most promising and exciting fields in cancer research. However, cancer vaccines have shown limited efficacy in clinical trials for several decades, which may be related to the unique and complex processes underlying tumor development and progression. Recent studies have indicated that tumors express highly specific neoantigens, which are distinct from self-antigens. Thus, developing cancer vaccines that target these tumor-specific neoantigens is a promising strategy for developing personalized cancer vaccines.