Cancer vaccine strategies: translation from mice to human clinical trials

RAS signaling and immune cells: a sinister crosstalk in the tumor microenvironment

The rat sarcoma virus (RAS) gene is the most commonly mutated oncogene in cancer, with about 19% of cancer patients carrying RAS mutations. Studies on the interaction between RAS mutation and tumor immune microenvironment (TIM) have been flourishing in recent years. More and more evidence has proved that RAS signals regulate immune cells' recruitment, activation, and differentiation while assisting tumor cells to evade immune surveillance. This review concluded the direct and indirect treatment strategies for RAS mutations. In addition, we updated the underlying mechanisms by which RAS signaling modulated immune infiltration and immune escape. Finally, we discussed advances in RAS-targeted immunotherapies, including cancer vaccines and adoptive cell therapies, with a particular focus on combination strategies with personalized therapy and great potential to achieve lasting clinical benefits.

The screening, identification, design and clinical application of tumor-specific neoantigens for TCR-T cells

Recent advances in neoantigen research have accelerated the development of tumor immunotherapies, including adoptive cell therapies (ACTs), cancer vaccines and antibody-based therapies, particularly for solid tumors. With the development of next-generation sequencing and bioinformatics technology, the rapid identification and prediction of tumor-specific antigens (TSAs) has become possible. Compared with tumor-associated antigens (TAAs), highly immunogenic TSAs provide new targets for personalized tumor immunotherapy and can be used as prospective indicators for predicting tumor patient survival, prognosis, and immune checkpoint blockade response. Here, the identification and characterization of neoantigens and the clinical application of neoantigen-based TCR-T immunotherapy strategies are summarized, and the current status, inherent challenges, and clinical translational potential of these strategies are discussed.

Light-responsive nanomedicine for cancer immunotherapy

Immunotherapy emerged as a paradigm shift in cancer treatments, which can effectively inhibit cancer progression by activating the immune system. Remarkable clinical outcomes have been achieved through recent advances in cancer immunotherapy, including checkpoint blockades, adoptive cellular therapy, cancer vaccine, and tumor microenvironment modulation. However, extending the application of immunotherapy in cancer patients has been limited by the low response rate and side effects such as autoimmune toxicities. With great progress being made in nanotechnology, nanomedicine has been exploited to overcome biological barriers for drug delivery. Given the spatiotemporal control, light-responsive nanomedicine is of great interest in designing precise modality for cancer immunotherapy. Herein, we summarized current research utilizing light-responsive nanoplatforms to enhance checkpoint blockade immunotherapy, facilitate targeted delivery of cancer vaccines, activate immune cell functions, and modulate tumor microenvironment. The clinical translation potential of those designs is highlighted and challenges for the next breakthrough in cancer immunotherapy are discussed.

Elicitation of potent neutralizing antibodies in obese mice by ISA 51-adjuvanted SARS-CoV-2 spike RBD-Fc vaccine

Vaccination is considered to be the most effective countermeasure to prevent and combat the global health threats of COVID-19. People with obesity are at a greater risk of hospitalization, life-threatening illness, and adverse outcomes after having COVID-19. Therefore, a safe and effective COVID-19 vaccine for obese individuals is urgently needed. In the study, the vaccine composed of the ISA 51 adjuvant and the SARS-CoV-2 spike (S) receptor-binding domain (RBD) in conjugation with the human IgG1 Fc fragment (named as ISA 51-adjuvanted RBD-Fc vaccine) was developed and inoculated in the regular chow diet (RCD) lean mice and the high-fat diet (HFD)-induced obese mice. The S protein-specific IgG titers were largely induced in an increasing manner along with three doses of ISA 51-adjuvanted RBD-Fc vaccine without causing any harmful side effect. In the HFD mice, the S protein-specific IgG titers can be quickly observed 2 weeks post the first inoculation. The antisera elicited by the ISA 51-adjuvanted RBD-Fc vaccine in the RCD and HFD mice exhibited potent SARS-CoV-2 neutralizing activities in the plaque reduction neutralization test (PRNT) assays and showed similar specificity for recognizing the key residues in the RBD which were involved in interacting with angiotensin-converting enzyme 2 (ACE2) receptor. The immune efficacy of the ISA 51-adjuvanted RBD-Fc vaccine in the HFD mice can be sustainably maintained with the PRNT50 values of 1.80-1.91×10^-3 for at least 8 weeks post the third inoculation. Collectively, the RBD-Fc-based immunogen and the ISA 51-adjuvanted formulation can be developed as an effective COVID-19 vaccine for obese individuals. KEY POINTS: • The ISA 51-adjuvanted RBD-Fc vaccine can induce potent SARS-CoV-2 neutralizing antibodies in the obese mouse • The antibodies elicited by the ISA 51-adjuvanted RBD-Fc vaccine can bind to the key RBD residues involved in interacting with ACE2 • The immune efficacy of the ISA 51-adjuvanted RBD-Fc vaccine can be sustainably maintained for at least 8 weeks post the third inoculation.

Recent advancements in immunotherapy of melanoma using nanotechnology-based strategies

Melanoma is a malignant tumor that accounts for the deadliest form of skin cancers. Despite the significant efforts made recently for development of immunotherapeutic strategies including using immune checkpoint inhibitors and cancer vaccines, the clinical outcomes are unsatisfying. Different factors affect efficient cancer immunotherapy such as side-effects, immunosuppressive tumor microenvironment, and tumor heterogeneity. In the past decades, various nanotechnology-based approaches have been developed to enhance the efficacy of cancer immunotherapy, in addition to diminishing the toxicity associated with it. Several studies have shown that proper application of nanomaterials can revolutionize the outcome of immunotherapy in diverse melanoma models. This review summarizes the recent advancement in the integration of nanotechnology and cancer immunotherapy in melanoma treatment. The importance of nanomaterials and their therapeutic advantages for patients with melanoma are also discussed.

Biomimetic Nanovaccines Potentiating Dendritic Cell Internalization via CXCR4-Mediated Macropinocytosis

Although targeted delivery of nanoparticulate vaccines to dendritic cells (DCs) holds tremendous potential, it still faces insufficient internalization and endosome degradation via the receptor-mediated endocytosis pathway. Inspired by the advantages of CXC-chemokine receptor type 4 (CXCR4)-mediated macropinocytosis in the internalization of DCs, a multifunctional vaccine is constructed based on a reactive oxygen species (ROS)-responsive nanoparticulate core and macropinocytosis-inducing peptide-fused cancer membrane shell, allowing the direct cytosolic delivery of cancer membrane-associated antigen and a stimulator of interferon genes (STING) agonist, cGAMP for highly efficient cancer immunotherapy. The biomimetic nanovaccines show a dramatically enhanced cellular uptake by DCs via CXCR4-mediated macropinocytosis. Such a direct delivery process promotes cytosolic release of cGAMP in response to ROS, and together promoted DC maturation and T cell priming by activating the STING pathway. Consequently, the biomimetic nanovaccines not only result in a great tumor rejection in prophylactic B16-F10 melanoma murine model, but also markedly suppress the growth of established melanoma tumors when combined with anti-PD-1 checkpoint blockade. This study advances the design of biomimetic nanovaccines and provides a promising strategy for macropinocytosis-mediated cancer vaccination.

Intratumoral delivery of dendritic cells plus anti-HER2 therapy triggers both robust systemic antitumor immunity and complete regression in HER2 mammary carcinoma

Background

Human epidermal growth factor receptor 2 (HER2) targeted antibodies in combination with chemotherapy has improved outcomes of HER2 positive (pos) breast cancer (BC) but toxicity of therapy remains a problem. High levels of tumor-infiltrating lymphocytes are associated with increased pathologic complete responses for patients treated with neoadjuvant therapy. Here we sought to investigate whether delivery of intratumoral (i.t.) multiepitope major histocompatibility complex (MHC) class II HER2 peptides-pulsed type I polarized dendritic cells (HER2-DC1) in combination with anti-HER2 antibodies without chemotherapy could enhance tumor regression by increasing anti-HER2 lymphocyte infiltration into the tumor.

Methods

BALB/c mice bearing orthotopic TUBO tumors, BALB/c mice bearing subcutaneous (s.c.) CT26 hHER2 tumors, or BALB-HER2/neu transgenic mice were all treated with i.t. or s.c. HER2-DC1, anti-HER2 antibodies, paclitaxel, T-DM1 or in combination. Immune response, host immune cells and effector function were analyzed using flow cytometry, interferon-γ ELISA and cytokine/chemokine arrays. The contributions of CD4⁺ and CD8⁺ T cells and antibody dependent cellular cytotoxicity (ADCC) were assessed using depleting antibodies and FcγR KO mice. Molecular changes were evaluated by immunohistochemistry and western blot.

Results

HER2-DC1 combined with anti-HER2 antibodies delivered i.t. compared to s.c. induced complete tumor regression in 75–80% of treated mice, with increased tumor infiltrating CD4⁺ and CD8⁺ T, B, natural killer T cells (NKT) and natural killer cells, and strong anti-HER2 responses in all HER2^pos BC models tested. The therapy caused regression of untreated distant tumors. Labeled HER2-DC1 migrated prominently into the distant tumor and induced infiltration of various DC subsets into tumors. HER2-DC1 i.t. combined with anti-HER2 antibodies displayed superior antitumor response compared to standard chemotherapy with anti-HER2 antibodies. Lasting immunity was attained which prevented secondary tumor formation. The presence of CD4⁺ and CD8⁺ T cells and ADCC were required for complete tumor regression. In the HER2^pos BC models, HER2-DC1 i.t. combined with anti-HER2 antibodies effectively diminished activation of HER2-mediated oncogenic signaling pathways.

Conclusions

HER2-DC1 i.t. with anti-HER2 antibodies mediates tumor regression through combined activation of T and B cell compartments and provides evidence that HER2-DC1 i.t. in combination with anti-HER2 antibodies can be tested as an effective alternative therapeutic strategy to current chemotherapy and anti-HER2 antibodies in HER2^pos BC.

Design of a new multi-epitope peptide vaccine for non-small cell Lung cancer via vaccinology methods: an in silico study

Lung cancer is the most common type of tumor worldwide. Non-small-cell lung carcinoma (NSCLC) is considered any epithelial cell-related lung cancer, which includes more than 85% of all lung cancer cases. NSCLC is less responsive to chemotherapy than SCLC. Therefore, the need for other treatments has become more pronounced and immunotherapy has gained increasing attention as a promising therapy in recent years. The current study aimed to design a multi-epitope peptide vaccine targeting main cancer/testis antigens of SP17, AKAP4, and PTTG1, which have a major function in tumor cell proliferation invasion. The protein vaccine was constructed using the rigorous immunoinformatics analysis and investigation of several immune system parameters, considering B cell epitopes and CD4 and CD8 induced epitopes as the most important cells to respond to cancer cells. Inverse translation and optimization of codons were performed to have the designed protein's cloning as well as expression potential in E.coli. Physicochemical, antigenic, and allergenic features were assessed to confirm the safety and immunogenicity of the vaccine. The secondary and tertiary structures were predicted. Finally, intrinsic disorder and 3D model refinement and validation were performed to eliminate structural problems. The designed construct had a stable structure that could be an antigen and stimulate the immune system and not be an allergen. The built model 3D structure was valid and stable. Further investigations are needed to approve the safety and immunogenic property of this new vaccine for NSCLC before it can be used in patients.

Spherical Nucleic Acid Vaccine Structure Markedly Influences Adaptive Immune Responses of Clinically Utilized Prostate Cancer Targets

Cancer vaccines, which activate the immune system against a target antigen, are attractive for prostate cancer, where multiple upregulated protein targets are identified. However, many clinical trials implementing peptides targeting these proteins have yielded suboptimal results. Using spherical nucleic acids (SNAs), we explore how precise architectural control of vaccine components can activate a robust antigen-specific immune response in comparison to clinical formulations of the same targets. The SNA vaccines incorporate peptides for human prostate-specific membrane antigen (PSMA) or T-cell receptor γ alternate reading frame protein (TARP) into an optimized architecture, resulting in high rates of immune activation and cytolytic ability in humanized mice and human peripheral blood mononuclear cells (hPBMCs). Specifically, administered SNAs elevate the production and secretion of cytokines and increase polyfunctional cytotoxic T cells and effector memory. Importantly, T cells raised from immunized mice potently kill targets, including clinically relevant cells expressing the whole PSMA protein. Treatment of hPBMCs increases costimulatory markers and cytolytically active T cells. This work demonstrates the importance of vaccine structure and its ability to reformulate and elevate clinical targets. Moreover, it encourages the field to reinvestigate ineffective peptide targets and repackage them into optimally structured vaccines to harness antigen potency and enhance clinical outcomes.

Short Review on Advances in Hydrogel-Based Drug Delivery Strategies for Cancer Immunotherapy

Cancer immunotherapy has become the new paradigm of cancer treatment. The introduction and discovery of various therapeutic agents have also accelerated the application of immunotherapy in clinical trials. However, despite the significant potency and demonstrated advantages of cancer immunotherapy, its clinical application to patients faces several safety and efficacy issues, including autoimmune reactions, cytokine release syndrome, and vascular leak syndrome-related issues. In addressing these problems, biomaterials traditionally used for tissue engineering and drug delivery are attracting attention. Among them, hydrogels can be easily injected into tumors with drugs, and they can minimize side effects by retaining immune therapeutics at the tumor site for a long time. This article reviews the status of functional hydrogels for effective cancer immunotherapy. First, we describe the basic mechanisms of cancer immunotherapy and the advantages of using hydrogels to apply these mechanisms. Next, we summarize recent advances in the development of functional hydrogels designed to locally release various immunotherapeutic agents, including cytokines, cancer immune vaccines, immune checkpoint inhibitors, and chimeric antigen receptor-T cells. Finally, we briefly discuss the current problems and possible prospects of hydrogels for effective cancer immunotherapy.

The Comprehensive "Omics" Approach from Metabolomics to Advanced Omics for Development of Immune Checkpoint Inhibitors: Potential Strategies for Next Generation of Cancer Immunotherapy

In the past decade, immunotherapies have been emerging as an effective way to treat cancer. Among several categories of immunotherapies, immune checkpoint inhibitors (ICIs) are the most well-known and widely used options for cancer treatment. Although several studies continue, this treatment option has yet to be developed into a precise application in the clinical setting. Recently, omics as a high-throughput technique for understanding the genome, transcriptome, proteome, and metabolome has revolutionized medical research and led to integrative interpretation to advance our understanding of biological systems. Advanced omics techniques, such as multi-omics, single-cell omics, and typical omics approaches, have been adopted to investigate various cancer immunotherapies. In this review, we highlight metabolomic studies regarding the development of ICIs involved in the discovery of targets or mechanisms of action and assessment of clinical outcomes, including drug response and resistance and propose biomarkers. Furthermore, we also discuss the genomics, proteomics, and advanced omics studies providing insights and comprehensive or novel approaches for ICI development. The overview of ICI studies suggests potential strategies for the development of other cancer immunotherapies using omics techniques in future studies.

HER2-antigen-specific humoral immune response in breast cancer lymphocytes transplanted in hu-PBL hIL-4 NOG mice

The status of humoral immunity of cancer patients is not clear compared to cellular immunity because the ability of specific antibody production is difficult to analyze in vitro. We previously developed a humanized mouse model to evaluate antigen-specific antibody production by transplanting human peripheral blood mononuclear cells (PBMCs) into NOG-hIL-4-Tg mice (hu-PBL hIL-4 NOG). In this study, these mice were transplanted with PBMCs derived from breast cancer patients (BC) and immunized with a human epidermal growth factor receptor 2 (HER2) peptide, CH401MAP, to analyze humoral immunity of BCs. The hu-PBL hIL-4 NOG mice recapitulated immune environment of BCs as the ratio of CD8+/CD4+T cells was lower and that of PD-1 + T cells was higher compared to healthy donors (HDs). Diverse clusters were detected in BC-mouse (BC-M) plasma components involving immunoglobulins and complements unlike HD-M, and there was a significant diversity in CH401MAP-specific IgG titers in BC-M. The number of B cell clones producing high CH401MAP-specific IgG was not increased by immunization in BC-M unlike HD-M. These results demonstrated that the humoral immunity of BCs appeared as diverse phenotypes different from HDs in hu-PBL hIL-4 NOG mice, which may provide important information for the study of personalized medicine.

TARP as antigen in cancer immunotherapy

In recent decades, immunotherapy has become a pivotal element in cancer treatment. A remaining challenge is the identification of cancer-associated antigens suitable as targets for immunotherapeutics with potent on-target and few off-tumor effects. The T-cell receptor gamma (TCRγ) chain alternate reading frame protein (TARP) was first discovered in the human prostate and androgen-sensitive prostate cancer. Thereafter, TARP was also identified in breast and endometrial cancers, salivary gland tumors, and pediatric and adult acute myeloid leukemia. Interestingly, TARP promotes tumor cell proliferation and migration, which is reflected in an association with worse survival. TARP expression in malignant cells, its role in oncogenesis, and its limited expression in normal tissues raised interest in its potential utility as a therapeutic target, and led to development of immunotherapeutic targeting strategies. In this review, we provide an overview of TARP expression, its role in different cancer types, and currently investigated TARP-directed immunotherapeutic options.

Tumor-associated autoantibodies from mouse breast cancer models are found in serum of breast cancer patients

B cell responses to tumor antigens occur early in breast tumors and may identify immunogenic drivers of tumorigenesis. Sixty-two candidate antigens were identified prior to palpable tumor development in TgMMTV-neu and C3(1)Tag transgenic mouse mammary tumor models. Five antigens (VPS35, ARPC2, SERBP1, KRT8, and PDIA6) were selected because their decreased expression decreased survival in human HER2 positive and triple negative cell lines in a siRNA screen. Vaccination with antigen-specific epitopes, conserved between mouse and human, inhibited tumor growth in both transgenic mouse models. Increased IgG autoantibodies to the antigens were elevated in serum from women with ductal carcinoma in situ (DCIS) and invasive breast cancer (IBC). The autoantibodies differentiated women with DCIS from control with AUC 0.93 (95% CI 0.88-0.98, p < 0.0001). The tumor antigens identified early in the development of breast cancer in mouse mammary tumor models were conserved in human disease, and potentially identify early diagnostic markers in human breast tumors.

Related parameters of affinity and stability prediction of HLA-A*2402 restricted antigen peptides based on molecular docking

Background

Major histocompatibility complex class I (MHC-I) plays an important role in cell immune response, and stable interaction between polypeptides and MHC-I ensures efficient presentation of polypeptide-MHC-I (pMHC-I) molecular complexes to T cells. The aim of this study was to explore ways to improve the affinity and stability of the p-Human Leukocyte Antigen (HLA)-A*2402 complex.

Methods

The peptide sequences of the restricted antigen peptides for HLA-A*2402 and the results of the in vitro competitive binding test were retrieved from the literature. The affinity values were predicted using NetMHCpan v4.1 server, and the stability values were predicted using the NetMHCstab v1.0 server. Auto Vina was used to dock peptides to HLA-A*2402 protein in a flexible docking manner, while Flexpepdock was employed to optimize the docking morphology. Maestro was used to analyze the intermolecular forces and the binding affinity of the complex, while MM-GBSA was used to calculate the binding free energy values.

Results

The intermolecular interactions that maintained the affinity and stability of peptide-HLA-A*2402 complex relied mainly on HB, followed by pi stack. The binding affinity values of molecular docking were associated with the predicted values of affinity and stability, the binding affinity and the binding free energy, as well as the intermolecular force pi-stack. The pi stack had a significant negative correlation with binding affinity and binding free energy. The replacement of the residues of the polypeptides that did not form pi-stack interactions with HLA-A*2402 improved the affinity and/or stability compared to before replacement.

Conclusions

The generation and increase in the number of pi-stacks between peptides and HLA-A*2402 molecules may help improve the affinity and stability of p-HLA-A*2402 complexes. The prediction of intermolecular forces and binding affinity of peptide-HLA by means of molecular docking is a supplement to the current commonly used prediction databases.

Biological roles of the B cell receptor-associated protein 31: Functional Implication in Cancer

BAP31 is a ubiquitously expressed integral membrane protein of the endoplasmic reticulum. BAP31 is involved in various biological and molecular processes, including protein transport, viral processing, apoptosis signaling, MHC 1 antigen processing and presentation, mitochondria and ER calcium regulation, and proteasomal protein degradation. We employed a BAP31 interaction search using STRING and inBioMap™ protein-protein interaction networks, and the Metabolic Atlas, which revealed molecular and metabolic interactors involved in various pathways essential for cell growth, cell survival, and disease development. BAP31, as a chaperone and resident protein of the ER, was reported in the development of some central nervous system disorders and metabolic diseases about AD, ALS, and Liver disease. In addition, BAP31 is overexpressed in many cancers. Furthermore, research around BAP31 involvement in cancer has taken up a shape, focusing on its roles in cancer cell survival, disease prognosis, and targeted treatment. Here, we address published data on the Biological roles of BAP31 in both health and disease. We present an analytical description of BAP31 expression and functional implication in some human cancers and the impact of its expression and regulation while it models as a potential target in cancer therapy. Besides, a profound understanding of BAP31 is insightful of the gap between cancer development and neurodegeneration, thus generating novel ideas surrounding the link between the two different cell phenomena.

Breast cancer stem cells, heterogeneity, targeting therapies and therapeutic implications

Both hereditary and sporadic breast cancer are suggested to develop from a stem cell subcomponent retaining most key stem cell properties but with dysregulation of self-renewal pathways, which drives tumorigenic differentiation and cellular heterogeneity. Cancer stem cells (CSCs), characterized by their self-renewal and differentiation potential, have been reported to contribute to chemo-/radio-resistance and tumor initiation and to be the main reason for the failure of current therapies in breast cancer and other CSC-bearing cancers. Thus, CSC-targeted therapies, such as those inducing CSC apoptosis and differentiation, inhibiting CSC self-renewal and division, and targeting the CSC niche to combat CSC activity, are needed and may become an important component of multimodal treatment. To date, the understanding of breast cancer has been extended by advances in CSC biology, providing more accurate prognostic and predictive information upon diagnosis. Recent improvements have enhanced the prospect of targeting breast cancer stem cells (BCSCs), which has shown promise for increasing the breast cancer remission rate. However, targeted therapy for breast cancer remains challenging due to tumor heterogeneity. One major challenge is determining the CSC properties that can be exploited as therapeutic targets. Another challenge is identifying suitable BCSC biomarkers to assess the efficacy of novel BCSC-targeted therapies. This review focuses mainly on the characteristics of BCSCs and the roles of BCSCs in the formation, maintenance and recurrence of breast cancer; self-renewal signaling pathways in BCSCs; the BCSC microenvironment; potential therapeutic targets related to BCSCs; and current therapies and clinical trials targeting BCSCs.

Clinical implication of cellular vaccine in glioma: current advances and future prospects

Gliomas, especially glioblastomas, represent one of the most aggressive and difficult-to-treat human brain tumors. In the last few decades, clinical immunotherapy has been developed and has provided exceptional achievements in checkpoint inhibitors and vaccines for cancer treatment. Immunization with cellular vaccines has the advantage of containing specific antigens and acceptable safety to potentially improve cancer therapy. Based on T cells, dendritic cells (DC), tumor cells and natural killer cells, the safety and feasibility of cellular vaccines have been validated in clinical trials for glioma treatment. For TAA engineered T cells, therapy mainly uses chimeric antigen receptors (IL13Rα2, EGFRvIII and HER2) and DNA methylation-induced technology (CT antigen) to activate the immune response. Autologous dendritic cells/tumor antigen vaccine (ADCTA) pulsed with tumor lysate and peptides elicit antigen-specific and cytotoxic T cell responses in patients with malignant gliomas, while its pro-survival effect is biased. Vaccinations using autologous tumor cells modified with TAAs or fusion with fibroblast cells are characterized by both effective humoral and cell-mediated immunity. Even though few therapeutic effects have been observed, most of this therapy showed safety and feasibility, asking for larger cohort studies and better guidelines to optimize cellular vaccine efficiency in anti-glioma therapy.

Monophosphoryl lipid A-induced activation of plasmacytoid dendritic cells enhances the anti-cancer effects of anti-PD-L1 antibodies

Monophosphoryl lipid A (MPLA) is a toll-like receptor 4 ligand that promotes immune activation in mice and humans, without undesired inflammation. Immunotherapy by the combining immune checkpoint blockade and MPLA has shown promising anti-cancer effects in both mice and humans. In this study, we explored how MPLA enhanced the anti-cancer effects of anti-PD-L1 antibodies (Abs). Anti-cancer immunity induced by the combination of anti-PD-L1 Abs and MPLA failed in CD4 and CD8 cell-depleted mice. Moreover, the combination treatment of anti-PD-L1 Abs and MPLA synergistically enhanced the activation of plasmacytoid dendritic cells (pDCs) in the mouse in vivo, while conventional DCs were not. In addition, mice treated with anti-PD-L1 Abs and MPLA were not protected from B16 melanoma by blockade of interferon-alpha receptor (IFNAR). The combination of anti-PD-L1 Abs and MPLA also promoted human peripheral blood pDC activation and induced IFN-α-dependent T cell activation. Therefore, these results demonstrate that MPLA enhances anti-PD-L1 Ab-mediated anti-cancer immunity through the activation and IFN-α production of pDCs.

Towards Breast Cancer Vaccines, Progress and Challenges

Breast cancer is the second leading cause of cancer death among women. National cancer institute of the US estimates that one in eight women will be diagnosed with breast cancer during their lifetime. Considering the devastating effects of the disease and the alarming numbers many scientists and research groups have devoted their research to fight breast cancer. Several recommendations are to be considered as preventing measures which include living a healthy lifestyle, regular physical activity, weight control and smoking cessation. Early detection of the disease by annual and regular mammography after the age of 40 is recommended by many healthcare institutions. This would help the diagnosis of the disease at an earlier stage and the start of the treatment before it is spread to other parts of the body. Current therapy for breast cancer includes surgical ablation, radiotherapy and chemotherapy which is often associated with adverse effects and even may lead to a relapse of the disease at a later stage. In order to achieve a long-lasting anticancer response with minimal adverse effects, development of breast cancer vaccines is under investigation by many laboratories. The immune system can be stimulated by a vaccine against breast cancer. This approach has attracted a great enthusiasm in recent years. No breast cancer vaccines have been approved for clinical use today. One breast cancer vaccine (NeuVax) has now completed clinical trial phase III and a few preventive and therapeutic breast cancer vaccines are at different steps of development. We think that with the recent advancements in immunotherapy, a breast cancer vaccine is not far from reach.

Advances in engineering local drug delivery systems for cancer immunotherapy

Cancer immunotherapy aims to leverage the immune system to suppress the growth of tumors and to inhibit metastasis. The recent promising clinical outcomes associated with cancer immunotherapy have prompted research and development efforts towards enhancing the efficacy of immune checkpoint blockade, cancer vaccines, cytokine therapy, and adoptive T cell therapy. Advancements in biomaterials, nanomedicine, and micro-/nano-technology have facilitated the development of enhanced local delivery systems for cancer immunotherapy, which can enhance treatment efficacy while minimizing toxicity. Furthermore, locally administered cancer therapies that combine immunotherapy with chemotherapy, radiotherapy, or phototherapy have the potential to achieve synergistic antitumor effects. Herein, the latest studies on local delivery systems for cancer immunotherapy are surveyed, with an emphasis on the therapeutic benefits associated with the design of biomaterials and nanomedicines. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Diversity Outbred Mice Reveal the Quantitative Trait Locus and Regulatory Cells of HER2 Immunity

The genetic basis and mechanisms of disparate antitumor immune response was investigated in Diversity Outbred (DO) F1 mice that express human HER2. DO mouse stock samples nearly the entire genetic repertoire of the species. We crossed DO mice with syngeneic HER2 transgenic mice to study the genetics of an anti-self HER2 response in a healthy outbred population. Anti-HER2 IgG was induced by Ad/E2TM or naked pE2TM, both encoding HER2 extracellular and transmembrane domains. The response of DO F1 HER2 transgenic mice was remarkably variable. Still, immune sera inhibited HER2+ SKBR3 cell survival in a dose-dependent fashion. Using DO quantitative trait locus (QTL) analysis, we mapped the QTL that influences both total IgG and IgG2(a/b/c) Ab response to either Ad/E2TM or pE2TM. QTL from these four datasets identified a region in chromosome 17 that was responsible for regulating the response. A/J and NOD segments of genes in this region drove elevated HER2 Ig levels. This region is rich in MHC-IB genes, several of which interact with inhibitory receptors of NK cells. (B6xA/J)F1 and (B6xNOD)F1 HER2 transgenic mice received Ad/E2TM after NK cell depletion, and they produced less HER2 IgG, demonstrating positive regulatory function of NK cells. Depletion of regulatory T cells enhanced response. Using DO QTL analysis, we show that MHC-IB reactive NK cells exert positive influence on the immunity, countering negative regulation by regulatory T cells. This new, to our knowledge, DO F1 platform is a powerful tool for revealing novel immune regulatory mechanisms and for testing new interventional strategies.

The Evolving Landscape of HER2-Directed Breast Cancer Therapy

OPINION STATEMENT

The management of patients with HER2+ breast cancer has evolved significantly over the preceding decades. HER2 targeting strategies have advanced beyond focusing on the receptor alone to encompass a range of approaches. Current standard of care practices in these patients relies upon dual HER2 blockade with trastuzumab and pertuzumab in the adjuvant and metastatic settings. T-DM1 has proven particularly efficacious in patients with residual disease status post neoadjuvant therapy, with additional therapies approved in the subsequent lines to address recurrent and resistant disease. Advances continue to be made in HER2+ breast cancer with multiple novel agents on the horizon, employing diverse mechanisms of action that are described in this review.

Optimized siRNA Delivery into Primary Immune Cells Using Electroporation

Effective RNA delivery strategies for primary human monocytes and dendritic cells (DCs) are useful tools for both basic research and cancer immunotherapy applications. Compared to viral delivery, electroporation is a relatively safe and simple technique that has been established for most immune cells. This chapter describes the feasibility of introducing small interfering RNAs into human primary monocytes and DCs using either nucleofection or standard electroporation techniques. DC cancer vaccines that integrate siRNA targeting relevant DC-intrinsic immunosuppressive signals induced robust and durable anti-tumor immune responses.

Trial watch: chemotherapy-induced immunogenic cell death in immuno-oncology

The term ‘immunogenic cell death’ (ICD) denotes an immunologically unique type of regulated cell death that enables, rather than suppresses, T cell-driven immune responses that are specific for antigens derived from the dying cells. The ability of ICD to elicit adaptive immunity heavily relies on the immunogenicity of dying cells, implying that such cells must encode and present antigens not covered by central tolerance (antigenicity), and deliver immunostimulatory molecules such as damage-associated molecular patterns and cytokines (adjuvanticity). Moreover, the host immune system must be equipped to detect the antigenicity and adjuvanticity of dying cells. As cancer (but not normal) cells express several antigens not covered by central tolerance, they can be driven into ICD by some therapeutic agents, including (but not limited to) chemotherapeutics of the anthracycline family, oxaliplatin and bortezomib, as well as radiation therapy. In this Trial Watch, we describe current trends in the preclinical and clinical development of ICD-eliciting chemotherapy as partner for immunotherapy, with a focus on trials assessing efficacy in the context of immunomonitoring.

Immunotherapy in HER2-positive breast cancer: state of the art and future perspectives

Breast cancer (BC) is a complex disease with primary or acquired incurability characteristics in a significant part of patients. Immunotherapeutical agents represent an emerging option for breast cancer treatment, including the human epidermal growth factor 2 positive (HER2+) subtype. The immune system holds the ability to spontaneously implement a defensive response against HER2+ BC cells through complex mechanisms which can be exploited to modulate this response for obtaining a clinical benefit. Initial immune system modulating strategies consisted mostly in vaccine therapies, which are still being investigated and improved. However, the entrance of trastuzumab into the scenery of HER2+ BC treatment was the real game changing event, which embodied a dominant immune-mediated mechanism. More recently, the advent of the immune checkpoint inhibitors has caused a new paradigm shift for immuno-oncology, with promising initial results also for HER2+ BC. Breast cancer has been traditionally considered poorly immunogenic, being characterized by relatively low tumor mutation burden (TMB). Nevertheless, recent evidence has revealed high tumor infiltrating lymphocytes (TILs) and programmed cell death-ligand 1 (PD-L1) expression in a considerable proportion of HER2+ BC patients. This may translate into a higher potential to elicit anti-cancer response and, therefore, wider possibilities for the use and implementation of immunotherapy in this subset of BC patients. We are herein presenting and critically discussing the most representative evidence concerning immunotherapy in HER2+ BC cancer, both singularly and in combination with therapeutic agents acting throughout HER2-block, immune checkpoint inhibition and anti-cancer vaccines. The reader will be also provided with hints concerning potential future projection of the most promising immutherapeutic agents and approaches for the disease of interest.

The emerging role of epigenetic therapeutics in immuno-oncology

The past decade has seen the emergence of immunotherapy as a prime approach to cancer treatment, revolutionizing the management of many types of cancer. Despite the promise of immunotherapy, most patients do not have a response or become resistant to treatment. Thus, identifying combinations that potentiate current immunotherapeutic approaches will be crucial. The combination of immune-checkpoint inhibition with epigenetic therapy is one such strategy that is being tested in clinical trials, encompassing a variety of cancer types. Studies have revealed key roles of epigenetic processes in regulating immune cell function and mediating antitumour immunity. These interactions make combined epigenetic therapy and immunotherapy an attractive approach to circumvent the limitations of immunotherapy alone. In this Review, we highlight the basic dynamic mechanisms underlying the synergy between immunotherapy and epigenetic therapies and detail current efforts to translate this knowledge into clinical benefit for patients.

Prospects for combining immune checkpoint blockade with PARP inhibition

The immunogenicity of a cancer cell is derived from accumulated somatic mutations. However, on the contrary to increased immunogenicity, anti-cancer immune response tends to be feeble. This impaired anti-cancer immunity could be attributed to multiple factors including loss of immunodominant epitopes, downregulation of major histocompatibility complex, and immunosuppressive microenvironment, as well as aberrant negative co-stimulatory signals. Immune checkpoint inhibitors block negative co-stimulatory signals such as programmed cell death-1 and cytotoxic T-lymphocyte-associated protein 4, ultimately reactivating anti-cancer immunity. Immune checkpoint inhibitors elicit potent anti-cancer effect and have been approved for multiple cancers. Nevertheless, there still are significant potential improvements for the applications of checkpoint inhibitor, especially considering frequent resistance. Recent studies demonstrated that additional PARP inhibition could alleviate resistance and enhance efficacy of immune checkpoint blockade therapy via promoting cross-presentation and modifying immune microenvironment. We proposed that PARP inhibitors could enhance the priming and tumor-killing activities of T cell, boost the whole cancer-immunity cycle, and thereby improve the response to immune checkpoint blockade. In this review, we focused the latest understanding of the effect of PARP inhibitors on anti-cancer immunity and PARP inhibitors combining immune checkpoint blockade therapy. Moreover, we summarized the preclinical and clinical evidence and discussed the feasibility of this combination therapy in future clinical practice.

Design of Outer Membrane Vesicles as Cancer Vaccines: A New Toolkit for Cancer Therapy

Cancer vaccines have been extensively studied in recent years and have contributed to exceptional achievements in cancer treatment. They are some of the most newly developed vaccines, although only two are currently approved for use, Provenge and Talimogene laherparepvec (T-VEC). Despite the approval of these two vaccines, most vaccines have been terminated at the clinical trial stage, which indicates that although they are effective in theory, concerns still exist, including low antigenicity of targeting antigens and tumor heterogeneity. In recent years, with new understanding of the biological function and vaccine potential of outer membrane vesicles (OMVs), their potential application in cancer vaccine design deserves our attention. Therefore, this review focuses on the mechanisms, advantages, and prospects of OMVs as antigen-carrier vaccines in cancer vaccine development. We believe that OMV-based vaccines present a safe and effective cancer therapeutic option with broad application prospects.

Trial watch: Peptide-based vaccines in anticancer therapy

Peptide-based anticancer vaccination aims at stimulating an immune response against one or multiple tumor-associated antigens (TAAs) following immunization with purified, recombinant or synthetically engineered epitopes. Despite high expectations, the peptide-based vaccines that have been explored in the clinic so far had limited therapeutic activity, largely due to cancer cell-intrinsic alterations that minimize antigenicity and/or changes in the tumor microenvironment that foster immunosuppression. Several strategies have been developed to overcome such limitations, including the use of immunostimulatory adjuvants, the co-treatment with cytotoxic anticancer therapies that enable the coordinated release of damage-associated molecular patterns, and the concomitant blockade of immune checkpoints. Personalized peptide-based vaccines are also being explored for therapeutic activity in the clinic. Here, we review recent preclinical and clinical progress in the use of peptide-based vaccines as anticancer therapeutics.Abbreviations: CMP: carbohydrate-mimetic peptide; CMV: cytomegalovirus; DC: dendritic cell; FDA: Food and Drug Administration; HPV: human papillomavirus; MDS: myelodysplastic syndrome; MHP: melanoma helper vaccine; NSCLC: non-small cell lung carcinoma; ODD: orphan drug designation; PPV: personalized peptide vaccination; SLP: synthetic long peptide; TAA: tumor-associated antigen; TNA: tumor neoantigen

Two tandem repeats of mHSP70407-426 enhance therapeutic antitumor effects of a recombined vascular endothelial growth factor (VEGF) protein vaccine

AIMS

Active immunization with human vascular endothelial growth factor (hVEGF) vaccines provides a therapeutic option instead of bevacizumab therapy. However, the immunity to self-molecule is difficult to elicit due to immune tolerance. A bioactive peptide of two tandem repeats of mHSP70_407-426 (M₂) has exhibited potent adjuvant ability in our previous study, and the aim of this study was to explore whether M₂ could assist hVEGF to display enhanced therapeutic anti-tumor effects.

MAIN METHODS

The anti-tumor effects of hVEGF-M₂ vaccine were evaluated in both H22 hepatocellular carcinoma and Lewis lung tumor models. CD31 analysis of excised tumors was used to evaluate anti-angiogenesis effects. The titers of anti-VEGF antibody was detected by ELISA and verified by western blot analyses, and the effects of immune sera on HUVEC differentiation were investigated by tube formation assay.

KEY FINDINGS

M₂ could assist hVEGF to exhibit more favorable therapeutic anti-tumor growth and metastasis effects than hVEGF. Meanwhile, high titer of anti-VEGF antibody was detected in hVEGF-M₂ immunized mice sera by ELISA and verified by western blot analysis. Sera from hVEGF-M₂ immunized mice could more significantly inhibit HUVEC tube formation than hVEGF immune serum. The hVEGF-M₂-immune sera could more effectively inhibit H22 tumor growth and extend the survival rates of H22 tumor bearing mice than hVEGF-immune sera. CD31 analysis of the excised tumors verified a significant reduction in vessel density after hVEGF-M₂ vaccination.

SIGNIFICANCE

M₂ could assist hVEGF to display enhanced anti-tumor effects, which are important for the further application of M₂ to enhance antigen-specific immune responses.