Therapeutic cancer vaccines: current status and moving forward

Revolutionizing Cancer Treatment: Unleashing the Power of Viral Vaccines, Monoclonal Antibodies, and Proteolysis-Targeting Chimeras in the New Era of Immunotherapy

In the realm of cancer immunotherapy, a profound evolution has ushered in sophisticated strategies that encompass both traditional cancer vaccines and emerging viral vaccines. This comprehensive Review offers an in-depth exploration of the methodologies, clinical applications, success stories, and future prospects of these approaches. Traditional cancer vaccines have undergone significant advancements utilizing diverse modalities such as proteins, peptides, and dendritic cells. More recent innovations have focused on the physiological mechanisms enabling the human body to recognize and combat precancerous and malignant cells, introducing specific markers like peptide-based anticancer vaccines targeting tumor-associated antigens. Moreover, cancer viral vaccines, leveraging engineered viruses to stimulate immune responses against specific antigens, exhibit substantial promise in inducing robust and enduring immunity. Integration with complementary therapeutic methods, including monoclonal antibodies, adjuvants, and radiation therapy, has not only improved survival rates but also deepened our understanding of viral virulence. Recent strides in vaccine design, encompassing oncolytic viruses, virus-like particles, and viral vectors, mark the frontier of innovation. While these advances hold immense potential, critical challenges must be addressed, such as strategies for immune evasion, potential off-target effects, and the optimization of viral genomes. In the landscape of immunotherapy, noteworthy innovations take the spotlight from the use of immunomodulatory agents for the enhancement of innate and adaptive immune collaboration. The emergence of proteolysis-targeting chimeras (PROTACs) as precision tools for cancer therapy is particularly exciting. With a focus on various cancers, from melanoma to formidable solid tumors, this Review critically assesses types of cancer vaccines, mechanisms, barriers in vaccine therapy, vaccine efficacy, safety profiles, and immune-related adverse events, providing a nuanced perspective on the underlying mechanisms involving cytotoxic T cells, natural killer cells, and dendritic cells. The Review also underscores the transformative potential of cutting-edge technologies such as clinical studies, molecular sequencing, and artificial intelligence in advancing the field of cancer vaccines. These tools not only expedite progress but also emphasize the multidimensional and rapidly evolving nature of this research, affirming its profound significance in the broader context of cancer therapy.

Immunoinformatics Approach to Design a Chimeric CD70-Peptide Vaccine against Renal Cell Carcinoma

Renal cell carcinoma (RCC) accounts for the majority of cancer-related deaths worldwide. Overexpression of CD70 has been linked to advanced stages of RCC. Therefore, this study aims to develop a multiepitope vaccine targeting the overexpressed CD70 using immunoinformatics techniques. In this investigation, in silico multiepitope vaccines were constructed by linking specific CD70 protein epitopes for helper T lymphocytes and CD8+ T lymphocytes. To enhance immunogenicity, sequences of cell-penetrating peptide (CPP), penetratin (pAntp), along with the entire sequence of tumor necrosis factor-α (TNF-α), were attached to the N-terminal and C-terminal of the CD70 epitopes. Computational assessments were performed on these chimeric vaccines for antigenicity, allergenicity, peptide toxicity, population coverage, and physicochemical properties. Furthermore, refined 3D constructs were subjected to a range of analyses, encompassing structural B-cell epitope prediction and molecular docking. The chosen vaccine construct underwent diverse assessments such as molecular dynamics simulation, immune response simulation, and in silico cloning. All vaccines comprised antigenic, nontoxic, and nonallergenic epitopes, ensuring extensive global population coverage. The vaccine constructs demonstrated favorable physicochemical characteristics. The binding affinity of chimeric vaccines to the TNF receptor remained relatively stable, influenced by the alignment of vaccine components. Molecular docking and dynamics analyses predicted stable interactions between CD70-CPP-TNF and the TNF receptor, indicating potential efficacy. In silico codon optimization and cloning of the vaccine nucleic acid sequence were accomplished using the pET28a plasmid. Furthermore, this vaccine displayed the capacity to modulate humoral and cellular immune responses. Overall, the results suggest therapeutic potential for the chimeric CD70-CPP-TNF vaccine against RCC. However, validation through in vitro and in vivo experiments is necessary. This trial is registered with NCT04696731 and NCT04046445.

Advances in Cancer Vaccine Research

The use of cancer vaccines is considered a promising therapeutic strategy in clinical oncology, which is achieved by stimulating antitumor immunity with tumor antigens delivered in the form of cells, peptides, viruses, and nucleic acids. The ideal cancer vaccine has many advantages, including low toxicity, specificity, and induction of persistent immune memory to overcome tumor heterogeneity and reverse the immunosuppressive microenvironment. Many therapeutic vaccines have entered clinical trials for a variety of cancers, including melanoma, breast cancer, lung cancer, and others. However, many challenges, including single antigen targeting, weak immunogenicity, off-target effects, and impaired immune response, have hindered their broad clinical translation. In this review, we introduce the principle of action, components (including antigens and adjuvants), and classification (according to applicable objects and preparation methods) of cancer vaccines, summarize the delivery methods of cancer vaccines, and review the clinical and theoretical research progress of cancer vaccines. We also present new insights into cancer vaccine technologies, platforms, and applications as well as an understanding of potential next-generation preventive and therapeutic vaccine technologies, providing a broader perspective for future vaccine design.

Surface modification strategies in translocating nano-vesicles across different barriers and the role of bio-vesicles in improving anticancer therapy

Nanovesicles and bio-vesicles (BVs) have emerged as promising tools to achieve targeted cancer therapy due to their ability to overcome many of the key challenges currently being faced with conventional chemotherapy. These challenges include the diverse and often complex pathophysiology involving the progression of cancer, as well as the various biological barriers that circumvent therapeutic molecules reaching their target site in optimum concentration. The scientific evidence suggests that surface-functionalized nanovesicles and BVs camouflaged nano-carriers (NCs) both can bypass the established biological barriers and facilitate fourth-generation targeting for the improved regimen of treatment. In this review, we intend to emphasize the role of surface-functionalized nanovesicles and BVs camouflaged NCs through various approaches that lead to an improved internalization to achieve improved and targeted oncotherapy. We have explored various strategies that have been employed to surface-functionalize and biologically modify these vesicles, including the use of biomolecule functionalized target ligands such as peptides, antibodies, and aptamers, as well as the targeting of specific receptors on cancer cells. Further, the utility of BVs, which are made from the membranes of cells such as mesenchymal stem cells (MSCs), white blood cells (WBCs), red blood cells (RBCs), platelets (PLTs) as well as cancer cells also been investigated. Lastly, we have discussed the translational challenges and limitations that these NCs can encounter and still need to be overcome in order to fully realize the potential of nanovesicles and BVs for targeted cancer therapy. The fundamental challenges that currently prevent successful cancer therapy and the necessity of novel delivery systems are in the offing.

Peptide Vaccines as Therapeutic and Prophylactic Agents for Female-Specific Cancers: The Current Landscape

Breast and gynecologic cancers are significant global threats to women's health and those living with the disease require lifelong physical, financial, and social support from their families, healthcare providers, and society as a whole. Cancer vaccines offer a promising means of inducing long-lasting immune response against the disease. Among various types of cancer vaccines available, peptide vaccines offer an effective strategy to elicit specific anti-tumor immune responses. Peptide vaccines have been developed based on tumor associated antigens (TAAs) and tumor specific neoantigens which can also be of viral origin. Molecular alterations in HER2 and non-HER2 genes are established to be involved in the pathogenesis of female-specific cancers and hence were exploited for the development of peptide vaccines against these diseases, most of which are in the latter stages of clinical trials. However, prophylactic vaccines for viral induced cancers, especially those against Human Papillomavirus (HPV) infection are well established. This review discusses therapeutic and prophylactic approaches for various types of female-specific cancers such as breast cancer and gynecologic cancers with special emphasis on peptide vaccines. We also present a pipeline for the design and evaluation of a multiepitope peptide vaccine that can be active against female-specific cancers.

Anti-PD-L1 antibody reverses the immune tolerance induced by multiple MUC1-MBP vaccine immunizations by increasing the CD80/PD-L1 ratio, resulting in DC maturation, and decreasing Treg activity in B16-MUC1 melanoma-bearing mice

In this study, we explored the possible mechanism of tumor tolerance induced by multiple repeated immunizations with a tumor vaccine (MUC1-MBP fusion protein plus CpG2006). We first analyzed the mechanism of tolerance by immunizing tumor-bearing mice 2, 5, or 8 times and found that compared with five immunizations with the M-M vaccine, eight immunizations increased tumor volume and weight and Treg levels, while the proportions of Th1 and Tc1 cells in the spleen and lymph nodes were decreased. In particular, the M-M vaccine induced PD-L1 expression in CD11c + DCs and decreased their CD80/PD-L1 ratio. Therefore, the mechanism of tolerance induction by multiple immunizations with the M-M vaccine was investigated by focusing on the CD80/PD-L1 ratio, and an anti-PD-L1 antibody (αPD-L1) and the M-M vaccine were used in combination to treat melanoma. The results showed that αPD-L1 increased the CD80/PD-L1 ratio and enhanced the maturation of cDC1s by blocking PD-L1 on DCs, which potentially increased the activity of Th1 and Tc1 cells. Furthermore, the combination of the M-M vaccine with αPD-L1 decreased the activity and proportion of Tregs, which reversed the immune tolerance induced by eight immunizations with the vaccine. This study reveals the mechanism of the combination of M-M and αPD-L1 and provides a new combination strategy for improving the therapeutic effect of the M-M vaccine, laying a theoretical basis for the clinical application of the vaccine.

Recombinant Strains of Oncolytic Vaccinia Virus for Cancer Immunotherapy

Cancer virotherapy is an alternative therapeutic approach based on the viruses that selectively infect and kill tumor cells. Vaccinia virus (VV) is a member of the Poxviridae, a family of enveloped viruses with a large linear double-stranded DNA genome. The proven safety of the VV strains as well as considerable transgene capacity of the viral genome, make VV an excellent platform for creating recombinant oncolytic viruses for cancer therapy. Furthermore, various genetic modifications can increase tumor selectivity and therapeutic efficacy of VV by arming it with the immune-modulatory genes or proapoptotic molecules, boosting the host immune system, and increasing cross-priming recognition of the tumor cells by T-cells or NK cells. In this review, we summarized the data on bioengineering approaches to develop recombinant VV strains for enhanced cancer immunotherapy.

Immunotherapy at the modern stage: types and tactics of application

The sum of the effects of all negative factors on the human body is manifested, including in the form of an imbalance in the work of the immune system, which leads to a violation of the recognition and elimination of foreign substances of the most diverse origin. This is manifested in an increase in the frequency of development of inflammatory processes, the risk of their chronicity and the development of complications, the identification of opportunistic or conditionally pathogenic flora as a pathogen, including those with atypical biological properties and antibiotic resistance. The use of etiotropic chemotherapy alone in the treatment does not allow achieving sufficient control over many infectious diseases. The purpose of this review was to investigate additional, alternative approaches to influencing anti-infective immunity. An analysis of the strategy based on the use of modulation of the immune response in the treatment of patients was carried out and its advantages over traditional antimicrobial treatment were determined. The concept of «immunotherapy» is discussed, which implies a variety of effects on the immune system in order to stop the pathological process. The review highlights the main types of immunotherapy - local, general, combined and monoimmunotherapy, as well as active and passive, specific and nonspecific. The review provides convincing data on the need for immunomodulators to meet a number of requirements, analyzes various ways of classifying them and their areas of application. The necessity of using immunotropic drugs on the basis of a comprehensive examination is emphasized, taking into account the correspondence between the nature of clinical manifestations and the severity of changes in immunological parameters. The analyzed data allow us to conclude that immunomodulatory therapy can be used to restore the function of the immune system to the physiological norm after a severe inflammatory process at the stage of immunorehabilitation.

A Novel Therapeutic Tumor Vaccine Targeting MUC1 in Combination with PD-L1 Elicits Specific Anti-Tumor Immunity in Mice

Dendritic cells (DCs), as professional antigen-presenting cells (APCs), play a key role in the initiation and regulation of humoral and cellular immunity. DC vaccines loaded with different tumor-associated antigens (TAAs) have been widely used to study their therapeutic effects on cancer. A number of clinical trials have shown that DCs are safe as an antitumor vaccine and can activate certain anti-tumor immune responses; however, the overall clinical efficacy of DC vaccine is not satisfactory, so its efficacy needs to be enhanced. MUC1 is a TAA with great potential, and the immune checkpoint PD-L1 also has great potential for tumor treatment. Both of them are highly expressed on the surface of various tumors. In this study, we generated a novel therapeutic MUC1-Vax tumor vaccine based on the method of PD-L1-Vax vaccine we recently developed; this novel PD-L1-containing MUC1-Vax vaccine demonstrated an elevated persistent anti-PD-L1 antibody production and elicited a much stronger protective cytotoxic T lymphocyte (CTL) response in immunized mice. Furthermore, the MUC1-Vax vaccine exhibited a significant therapeutic anti-tumor effect, which significantly inhibited tumor growth by expressing a high MUC1⁺ and PD-L1⁺ level of LLC and Panc02 tumor cells, and prolonged the survival of cancer-bearing animals. Taken together, our study provides a new immunotherapy strategy for improving the cross-presentation ability of therapeutic vaccine, which may be applicable to pancreatic cancer, lung cancer and for targeting other types of solid tumors that highly express MUC1 and PD-L1.

mRNA cancer vaccines: Advances, trends and challenges

Patients exhibit good tolerance to messenger ribonucleic acid (mRNA) vaccines, and the choice of encoded molecules is flexible and diverse. These vaccines can be engineered to express full-length antigens containing multiple epitopes without major histocompatibility complex (MHC) restriction, are relatively easy to control and can be rapidly mass produced. In 2021, the U.S. Food and Drug Administration (FDA) approved the first mRNA-based coronavirus disease 2019 (COVID-19) vaccine produced by Pfizer and BioNTech, which has generated enthusiasm for mRNA vaccine research and development. Based on the above characteristics and the development of mRNA vaccines, mRNA cancer vaccines have become a research hotspot and have undergone rapid development, especially in the last five years. This review analyzes the advances in mRNA cancer vaccines from various perspectives, including the selection and expression of antigens/targets, the application of vectors and adjuvants, different administration routes, and preclinical evaluation, to reflect the trends and challenges associated with these vaccines.

Vaccine Based on Dendritic Cells Electroporated with an Exogenous Ovalbumin Protein and Pulsed with Invariant Natural Killer T Cell Ligands Effectively Induces Antigen-Specific Antitumor Immunity

Simple Summary

This study shows the potential of a novel dendritic cell vaccine therapy in antitumor immunity, in which bone marrow-derived dendritic cells are electroporated with an exogenous ovalbumin protein and simultaneously pulsed with α-galactosylceramide. This strategy enhances the induction of cytotoxic CD8⁺ T cells specific for tumor-associated antigens through the activation of invariant natural killer T cells, natural killer cells, and intrinsic dendritic cells. Moreover, this strategy sustains antigen-specific antitumor T cell responses over time.

Abstract

(1) Background: Cancer vaccines are administered to induce cytotoxic CD8⁺ T cells (CTLs) specific for tumor antigens. Invariant natural killer T (iNKT) cells, the specific T cells activated by α-galactosylceramide (α-GalCer), play important roles in this process as they are involved in both innate and adaptive immunity. We developed a new cancer vaccine strategy in which dendritic cells (DCs) were loaded with an exogenous ovalbumin (OVA) protein by electroporation (EP) and pulsed with α-GalCer. (2) Methods: We generated bone marrow-derived DCs from C57BL/6 mice, loaded full-length ovalbumin proteins to the DCs by EP, and pulsed them with α-GalCer (OVA-EP-galDCs). The OVA-EP-galDCs were intravenously administered to C57BL/6 mice as a vaccine. We then investigated subsequent immune responses, such as the induction of iNKT cells, NK cells, intrinsic DCs, and OVA-specific CD8⁺ T cells, including tissue-resident memory T (T_RM) cells. (3) Results: The OVA-EP-galDC vaccine efficiently rejected subcutaneous tumors in a manner primarily dependent on CD8⁺ T cells. In addition to the OVA-specific CD8⁺ T cells both in early and late phases, we observed the induction of antigen-specific T_RM cells in the skin. (4) Conclusions: The OVA-EP-galDC vaccine efficiently induced antigen-specific antitumor immunity, which was sustained over time, as shown by the T_RM cells.

Head and Neck Squamous Cell Carcinoma: Risk Factors, Molecular Alterations, Immunology and Peptide Vaccines

Head and neck squamous cell carcinoma (HNSCC) arises from the epithelial lining of the oral cavity, hypopharynx, oropharynx, and larynx. There are several potential risk factors that cause the generation of HNSCC, including cigarette smoking, alcohol consumption, betel quid chewing, inadequate nutrition, poor oral hygiene, HPV and Epstein–Barr virus, and Candida albicans infections. HNSCC has causative links to both environmental factors and genetic mutations, with the latter playing a more critical role in cancer progression. These molecular changes to epithelial cells include the inactivation of cancer suppressor genes and proto-oncogenes overexpression, resulting in tumour cell proliferation and distant metastasis. HNSCC patients have impaired dendritic cell (DC) and natural killer (NK) cell functions, increased production of higher immune-suppressive molecules, loss of regulatory T cells and co-stimulatory molecules and major histocompatibility complex (MHC) class Ι molecules, lower number of lymphocyte subsets, and a poor response to antigen-presenting cells. At present, the standard treatment modalities for HNSCC patients include surgery, chemotherapy and radiotherapy, and combinatorial therapy. Despite advances in the development of novel treatment modalities over the last few decades, survival rates of HNSCC patients have not increased. To establish effective immunotherapies, a greater understanding of interactions between the immune system and HNSCC is required, and there is a particular need to develop novel therapeutic options. A therapeutic cancer vaccine has been proposed as a promising method to improve outcome by inducing a powerful adaptive immune response that leads to cancer cell elimination. Compared with other vaccines, peptide cancer vaccines are more robust and specific. In the past few years, there have been remarkable achievements in peptide-based vaccines for HNSCC patients. Here, we summarize the latest molecular alterations in HNSCC, explore the immune response to HNSCC, and discuss the latest developments in peptide-based cancer vaccine strategies. This review highlights areas for valuable future research focusing on peptide-based cancer vaccines.

Dendritic Cells and Cancer Immunotherapy: The Adjuvant Effect

Dendritic cells (DCs) are immune specialized cells playing a critical role in promoting immune response against antigens, and may represent important targets for therapeutic interventions in cancer. DCs can be stimulated ex vivo with pro-inflammatory molecules and loaded with tumor-specific antigen(s). Protocols describing the specific details of DCs vaccination manufacturing vary widely, but regardless of the employed protocol, the DCs vaccination safety and its ability to induce antitumor responses is clearly established. Many years of studies have focused on the ability of DCs to provide overall survival benefits at least for a selection of cancer patients. Lessons learned from early trials lead to the hypothesis that, to improve the efficacy of DCs-based immunotherapy, this should be combined with other treatments. Thus, the vaccine’s ultimate role may lie in the combinatorial approaches of DCs-based immunotherapy with chemotherapy and radiotherapy, more than in monotherapy. In this review, we address some key questions regarding the integration of DCs vaccination with multimodality therapy approaches for cancer treatment paradigms.

Multifunctional Biomedical Materials Derived from Biological Membranes

The delicate structure and fantastic functions of biological membranes are the successful evolutionary results of a long-term natural selection process. Their excellent biocompatibility and biofunctionality are widely utilized to construct multifunctional biomedical materials mainly by directly camouflaging materials with single or mixed biological membranes, decorating or incorporating materials with membrane-derived vesicles (e.g., exosomes), and designing multifunctional materials with the structure/functions of biological membranes. Here, the structure-function relationship of some important biological membranes and biomimetic membranes are discussed, such as various cell membranes, extracellular vesicles, and membranes from bacteria and organelles. Selected literature examples of multifunctional biomaterials derived from biological membranes for biomedical applications, such as drug- and gene-delivery systems, tissue-repair scaffolds, bioimaging, biosensors, and biological detection, are also highlighted. These designed materials show excellent properties, such as long circulation time, disease-targeted therapy, excellent biocompatibility, and selective recognition. Finally, perspectives and challenges associated with the clinical applications of biological-membrane-derived materials are discussed.

Gene Therapy Targeting p53 and KRAS for Colorectal Cancer Treatment: A Myth or the Way Forward?

Colorectal cancer (CRC) is the third most commonly diagnosed malignancy worldwide and is responsible as one of the main causes of mortality in both men and women. Despite massive efforts to raise public awareness on early screening and significant advancements in the treatment for CRC, the majority of cases are still being diagnosed at the advanced stage. This contributes to low survivability due to this cancer. CRC patients present various genetic changes and epigenetic modifications. The most common genetic alterations associated with CRC are p53 and KRAS mutations. Gene therapy targeting defect genes such as TP53 (tumor suppressor gene encodes for p53) and KRAS (oncogene) in CRC potentially serves as an alternative treatment avenue for the disease in addition to the standard therapy. For the last decade, significant developments have been seen in gene therapy for translational purposes in treating various cancers. This includes the development of vectors as delivery vehicles. Despite the optimism revolving around targeted gene therapy for cancer treatment, it also has various limitations, such as a lack of availability of related technology, high cost of the involved procedures, and ethical issues. This article will provide a review on the potentials and challenges of gene therapy targeting p53 and KRAS for the treatment of CRC.

Immunotherapy for non-small cell lung cancer (NSCLC), as a stand-alone and in combination therapy

Non-small cell lung cancer (NSCLC) is of major concern for society as it is associated with high mortality and is one of the most commonly occurring of all cancers. Due to the number of mutational variants and general heterogeneity of this type of cancer, treatment using conventional modalities has been challenging. Therefore, it is important to have improved therapeutic treatments like immunotherapy, that can specifically treat the disease while causing minimal damage to healthy tissue and additionally provide systemic immunity. Cancer vaccines are an important element of cancer immunotherapy and have been approved for treatment of a limited number of cancers, including NSCLC. This article highlights scientific evidence for several therapeutic treatment strategies for NSCLC, alone or in combination, which offers new hope for those suffering. Although cancer vaccines have had some success as a monotherapy, their potential in a combination therapy needs to be critically analyzed for future applications.

Synergistic Activation of Antitumor Immunity by a Particulate Therapeutic Vaccine

Success in anticancer immune therapy relies on stimulation of tumor antigen-specific T lymphocytes and effective infiltration of the T cells into tumor tissue. Here, a therapeutic vaccine that promotes proliferation and tumor infiltration of antigen-specific T cells in both inflamed and noninflamed tumor types is described. The vaccine consists of STING agonist 2'3'-cGAMP, TLR9 ligand CpG, and tumor antigen peptides that are loaded into nanoporous microparticles (μGCVax). μGCVax is effective in inhibiting lung metastatic melanoma, primary breast cancer, and subcutaneous colorectal cancer in their respective murine models, including functional cure of HER2-positive breast cancer. Mechanistically, μGCVax potently stimulates type I interferon expression in dendritic cells, and promotes CD8+ and CD103+ dendritic cell maturation and migration to lymph nodes and other lymphatic tissues. Antitumor responses are dependent on TLR9 and interferon α/β receptor signaling, and to a less extent on STING signaling. These results demonstrate a high potential for μGCVax in mediating antitumor immunity in personalized cancer therapy.

The ROC of Cox proportional hazards cure models with application in cancer studies

With recent advancement in cancer screening and treatment, many patients with cancers are identified at early stage and clinically cured. Importantly, uncured patients should be treated timely before the cancer progresses to advanced stages for which therapeutic options are rather limited. It is also crucial to identify uncured subjects among patients with early-stage cancers for clinical trials to develop effective adjuvant therapies. Thus, it is of interest to develop statistical predictive models with as high accuracy as possible in predicting the latent cure status. The receiver operating characteristic curve (ROC) and the area under the ROC curve (AUC) are among the most widely used statistical metrics for assessing predictive accuracy or discriminatory power for a dichotomous outcome (cured/uncured). Yet the conventional AUC cannot be directly used due to incompletely observed cure status. In this article, we proposed new estimates of the ROC curve and its AUC for predicting latent cure status in Cox proportional hazards (PH) cure models and transformation cure models. We developed explicit formulas to estimate sensitivity, specificity, the ROC and its AUC without requiring to know the patient cure status. We also developed EM type estimates to approximate sensitivity, specificity, ROC and AUC conditional on observed data. Numerical studies were used to assess their finite-sample performance of the proposed methods. Both methods are consistent and have similar efficiency as shown in our numerical studies. A melanoma dataset was used to demonstrate the utility of the proposed estimates of the ROC curve for the latent cure status. We also have developed an [Formula: see text] package called [Formula: see text] to efficiently compute the proposed estimates.

Brain Tumor Vaccines

Peptide and dendritic cell vaccines activate the immune system against tumor antigens to combat brain tumors. Vaccines stimulate a systemic immune response by inducing both antitumor T cells as well as humoral immunity through antibody production to cross the blood-brain barrier and combat brain tumors. Recent trials investigating vaccines against peptides (ie, epithelial growth factor receptor variant III, survivin, heat shock proteins, or personalized tumor antigens) and dendritic cells pulsed with known peptides, messenger RNA or unknown tumor lysate targets demonstrate the potential for therapeutic cancer vaccines to become an important therapy for brain tumor treatment.

L-BLP25 vaccine plus letrozole for breast cancer: Is translation possible?

We have recently reported immunomodulatory effects for tamoxifen and letrozole on the L-BLP25 (Stimuvax(®))-induced immune response in a MUC1-expressing breast cancer mouse model. While neither tamoxifen nor letrozole appeared to interfere with the Th1-polarized cytokine response induced by L-BLP25, only letrozole increased the survival advantage of L-BLP25.

Autochthonous T cells to the rescue: IL-10 directly activates tumor-resident CD8(+) T cells

Successful cancer immunotherapy is thought to require de novo priming of tumor specific CD8⁺ T cells in lymphatic organs. Contrasting these beliefs, cancer therapy based on interleukin-10 (IL-10) results in tumor rejection without a requirement for T-cell trafficking from lymphatic organs. Rather, IL-10 directly activates autochthonous, tumor-resident CD8⁺ T cells.

Cancer immunotherapy: a promising dawn in cancer research

Cancer is a highly proliferative disease, which is caused due to the loss of regulation of cell cycle and apoptosis, DNA damage, faulty repair system etc. The cancer microenvironment plays a pivotal role in disease progression as they contain different types of innate and adaptive immune cells. The most important molecules that establish a correlation between inflammation, innate immunity, adaptive immunity, and cancer are the molecules released by inflammatory cells in cancer microenvironment. These molecules secreted by the immune cells, which might activate a pro-tumorigenic and anti-tumorigenic response in cancer. In inflammatory microenvironment, the equilibrium state of immunosuppressive and immunostimulatory signals are important in tumor suppression. The immunotherapeutic approaches could be more effective in cancer treatment. However, advancement in immunobiology and cancer are improving the prospects of immunotherapy alone and/or in combination with the conventional therapies. Thus, the review attempts to highlight a promising and futuristic immunotherapeutic approach in combination with conventional treatment modalities.

Nanoparticle cancer vaccines: Design considerations and recent advances

Vaccines therapeutics manipulate host's immune system and have broad potential for cancer prevention and treatment. However, due to poor immunogenicity and limited safety, fewer cancer vaccines have been successful in clinical trials. Over the past decades, nanotechnology has been exploited to deliver cancer vaccines, eliciting long-lasting and effective immune responses. Compared to traditional vaccines, cancer vaccines delivered by nanomaterials can be tuned towards desired immune profiles by (1) optimizing the physicochemical properties of the nanomaterial carriers, (2) modifying the nanomaterials with targeting molecules, or (3) co-encapsulating with immunostimulators. In order to develop vaccines with desired immunogenicity, a thorough understanding of parameters that affect immune responses is required. Herein, we discussed the effects of physicochemical properties on antigen presentation and immune response, including but not limited to size, particle rigidity, intrinsic immunogenicity. Furthermore, we provided a detailed overview of recent preclinical and clinical advances in nanotechnology for cancer vaccines, and considerations for future directions in advancing the vaccine platform to widespread anti-cancer applications.

A Review on Nano-Based Drug Delivery System for Cancer Chemoimmunotherapy

Although notable progress has been made on novel cancer treatments, the overall survival rate and therapeutic effects are still unsatisfactory for cancer patients. Chemoimmunotherapy, combining chemotherapeutics and immunotherapeutic drugs, has emerged as a promising approach for cancer treatment, with the advantages of cooperating two kinds of treatment mechanism, reducing the dosage of the drug and enhancing therapeutic effect. Moreover, nano-based drug delivery system (NDDS) was applied to encapsulate chemotherapeutic agents and exhibited outstanding properties such as targeted delivery, tumor microenvironment response and site-specific release. Several nanocarriers have been approved in clinical cancer chemotherapy and showed significant improvement in therapeutic efficiency compared with traditional formulations, such as liposomes (Doxil®, Lipusu®), nanoparticles (Abraxane®) and micelles (Genexol-PM®). The applications of NDDS to chemoimmunotherapy would be a powerful strategy for future cancer treatment, which could greatly enhance the therapeutic efficacy, reduce the side effects and optimize the clinical outcomes of cancer patients. Herein, the current approaches of cancer immunotherapy and chemoimmunotherapy were discussed, and recent advances of NDDS applied for chemoimmunotherapy were further reviewed.

[Development of the drug oncolytic immunotherapy based on vaccinia viruses (Vaccinia virus, Orthopoxvirus, Chordopoxvirinae, Poxviridae) against breast cancer.]

INTRODUCTION

Currently, new directions in cancer therapy are actively developing, one of which is oncolytic immunotherapy. This approach would be to use of viruses as cancer specific cytolytic agents capable of stimulating both the tumor-specific and non-specific immune response. The objective paper was obtain a recombinant vaccinia virus containing genes encoding immunostimulating molecules and study oncolytic and immunostimulating properties of recombinant virus.

MATERIAL AND METHODS

MTT test, ELISA, methods of transient dominant selection.

RESULTS

The recombinant vaccinia virus (L-IVP_oncoB) were obtained with deletion of the gene encoding thymidine kinase and had an integrated gene encoding GM-CSF. Also the virus have deletion of the gene encoding viral growth factor and integrated genes encoding synthetic tumor-specific polyepitopic immunogens. It was shown that the modifications made to the viral genome did not affect the growth characteristics of the virus when cultured on CV-1 and 4647 cell cultures, and the cytopathogenic efficacy of the virus was determined in relation to cancer cultures of cells of various genesis. In in vivo experiment, it was revealed that the polyepitopic construct in the genome L-IVP_oncoB is able to initiate a change in the profile of cytokines.

DISCUSSION

The obtained data characterized L-IVP_oncoB as a promising cytopathogenic and immunostimulating agent and showed the need for further study of its properties as means of oncolytic immunotherapy.

CONCLUSION

The basic experiments on the evaluation of the biological properties of the obtained L-IVP_oncoB, which are necessary for the characterization of the oncolytic virus, have been carried out.

Putting the Pieces Together: Completing the Mechanism of Action Jigsaw for Sipuleucel-T

Sipuleucel-T is an autologous cellular immunotherapy that induces an immune response targeted against prostatic acid phosphatase (PAP) to treat asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer. In the phase III IMPACT study, sipuleucel-T was associated with a statistically significantly increased overall survival (OS) (median = 4.1 months) vs placebo. Patients with baseline prostate-specific antigen levels in the lowest quartile (≤22.1 ng/mL) exhibited a 13-month improvement in OS with sipuleucel-T. Together, this led sipuleucel-T to be approved and recommended as first-line therapy in various guidelines for treatment of metastatic castration-resistant prostate cancer. This review discusses the varied findings about the mechanisms of action of sipuleucel-T, bringing them together to form a more coherent picture. These pieces include inducing a statistically significant increase in antigen-presenting cell activation; inducing a peripheral immune response specific to the target (PAP) and/or immunizing (PA2024) antigens; stimulating systemic cytotoxic T-lymphocyte activity; and mediating antigen spread (ie, increased antibody responses to secondary proteins in addition to PAP and PA2024). Each of these pieces individually correlates with OS. Sipuleucel-T also traffics T cells to the prostate and is associated with long-term immune memory such that a second course of treatment induces an anamnestic immune response. Prostate cancer does not have a strongly inflamed microenvironment, thus its response to immune checkpoint inhibitors is limited. Because sipuleucel-T is able to traffic T cells to the tumor, it may be an ideal combination partner with immunotherapies including immune checkpoint inhibitors or with radiation therapy.

Cell membrane-camouflaged nanoparticles as drug carriers for cancer therapy

The translocation of natural cell membranes to the surface of synthetic nanoparticles, which allows man-made vectors to share merits and functionalities created by nature, has been a hot subject of research in the past decade. The resulting biomimetic nanoparticles not only retain the physicochemical properties of nanomaterials, but also inherit the advantageous functions of source cells. Combined with the preponderances of both synthetic and natural platforms, the optimized biomimetic systems can maximize the drug delivery efficiency. In this review, we first summarize the preparation strategies of the biomimetic systems from the perspective of the correlation between the properties of nanoparticles and cell membranes. Six types of cell membrane-camouflaged nanoparticles are further introduced with an emphasis on their properties and performance. Finally, a concluding remark regarding the primary challenges and opportunities associated with these nanoparticles is presented. STATEMENT OF SIGNIFICANCE: Translocation of natural cell membranes to the surface of synthetic nanoparticles has been repeatedly highlighted in the past decade to endow man-made vectors with merits and functionalities created by nature; therefore, the resulting biomimetic systems not only retain the physicochemical properties of nanomaterials but also inherit the biological functions of source cells for efficient drug delivery. To provide a timely review on this hot and rapidly developing subject of research, this paper summarized recent progress on the cell membrane-camouflaged nanoparticles as drug carriers for cancer therapy, and focused primarily on six different types of cell membrane-coated nanoparticles with an emphasis on the preparation strategies from the perspective of the correlation between the properties of nanoparticles and cell membrane.

Photodynamic Therapy-Based Dendritic Cell Vaccination Suited to Treat Peritoneal Mesothelioma

The potential of dendritic cell (DC)-based immunotherapy to treat cancer is, nowadays, well documented. Still, the clinical success of immune checkpoint inhibitors has dampened the interest in anticancer DC vaccination. For highly life-threatening tumors that are regarded as nonimmunogenic, such as mesothelioma, however, T helper 1 immunity-biased DC-based immunotherapy could still represent an attractive strategy. In this study, we took advantage of photodynamic therapy (PDT) to induce immunogenic cell death to generate mesothelioma cell lysates for DC priming and evaluated such a vaccine to treat peritoneal mesothelioma. We found that the white light in vitro activation of the photosensitizer OR141 led to mesothelioma cell death, together with the release of bona fide danger signals that promote DC maturation. The administration of a PDT-based DC vaccine to mice bearing peritoneal mesothelioma led to highly significant survival when compared with sham or control animals treated with anti-CTLA4 antibodies. This was further supported by a strong CD8⁺ and CD4⁺ T cell response, characterized by an increased proliferation, cytotoxic activities and the expression of activation markers, including interferon gamma (IFNγ). Moreover, the PDT-based DC vaccine led to a significant increase in IFNγ⁺ T cells infiltered within mesothelioma, as determined by flow cytometry and immunohistochemistry. Finally, in vivo tracking of intraperitoneally administered DCs led us to document rapid chemotaxis towards tumor-occupied lymphatics (vs. lipopolysaccharide (LPS)-treated DC). DCs pulsed with PDT-killed mesothelioma cells also exhibited a significant increase in CCR7 receptors, together with an intrinsic capacity to migrate towards the lymph nodes. Altogether, these results indicate that PDT-based DC vaccination is particularly suited to induce a potent immune response against peritoneal mesothelioma.

Safety and Efficacy of Therapeutic Cancer Vaccines Alone or in Combination With Immune Checkpoint Inhibitors in Cancer Treatment

Therapeutic cancer vaccines have proven to seldom induce dramatic clinical response when used alone, and therefore, they are being studied in combination with additional treatment modalities to achieve optimal treatment activities. Growing preclinical data show that combining vaccines and immune checkpoint inhibitors (ICIs) can prime intensified immunogenicity and modulate immunosuppressive tumor microenvironment. Herein, we focus on the safety and efficacy of approved and promising cancer vaccines alone or combined with ICIs in the treatment of several malignancies. Generally, the majority of clinical trials support the concept of synergy that combination therapy of vaccines and ICIs holds maximized potential to improve clinical outcomes. Importantly, the combination has acceptable safety and minimal additional toxicity compared with single-agent vaccines or ICIs. Additionally, the potential strategies of combining personalized tumor vaccines with ICIs will become priority option and future direction of vaccine development and application and the urgent need to develop effective biomarkers to screen appropriate patient populations and predict response to combination therapy.

Immunotherapy: breaching the barriers for cancer treatment

The great ambition to treat cancer through harnessing a patient's own immune responses has started to become reality. Clinical trials have shown impressive results and some patients reaching the end of existing treatment options have achieved full remission. Yet the response rate even within the most promising trials remain at just 30-40% of patients. To date, the focus of immunotherapy research has been to identify tumour antigens, and to enhance activation of effector lymphocytes. Yet this is only the first step to effective immunotherapy for a broader range of patients. Activated cytotoxic T cells can only act on their tumour cell targets if they have free and easy access to all tumour regions. Solid tumours are complex, heterogeneous environments which vary greatly in their physical properties. We must now focus our efforts on understanding how factors such as the composition, density and geometry of tumour extracellular matrix acts to impede or promote immune cell infiltration and activation, and work to design novel pharmacological interventions which restore and enhance leucocyte trafficking within solid tumours. This article is part of a discussion meeting issue 'Forces in cancer: interdisciplinary approaches in tumour mechanobiology'.

Novel immunotherapeutic approaches for hepatocellular carcinoma treatment

INTRODUCTION

The introduction of immune checkpoint inhibitors has been lately proposed for the treatment of hepatocellular carcinoma (HCC) with respect to other cancer types. Several immunotherapeutic approaches are now under evaluation for HCC treatment including: i) antibodies acting as immune checkpoint inhibitors; ii) antibodies targeting specific tumor-associated antigens; iii) chimeric antigen receptor redirected T (CAR-T) cells targeting specific tumor-associated antigens; iv) vaccination strategies with tumor-specific epitopes. Areas covered: The review provides a wide description of the clinical trials investigating the efficacy of the main immunotherapeutic approaches proposed for the treatment of patients affected by HCC. Expert opinion: The balancing between immunostimulative and immunosuppressive factors in the context of HCC tumor microenvironment results in heterogeneous response rates to immunotherapeutic approaches such as checkpoint inhibitors, among HCC patients. In this context, it becomes crucial the identification of predictive factors determining the treatment response. A multiple approach using different biomarkers could be useful to identify the subgroup of HCC patients responsive to the treatment with a checkpoint inhibitor (as an example, nivolumab) as single agent, and to identify those patients in which other treatment regimens, such as the combination with sorafenib, or with locoregional therapies, could be more effective.

Cancer DNA vaccines: current preclinical and clinical developments and future perspectives

The recent developments in immuno-oncology have opened an unprecedented avenue for the emergence of vaccine strategies. Therapeutic DNA cancer vaccines are now considered a very promising strategy to activate the immune system against cancer. In the past, several clinical trials using plasmid DNA vaccines demonstrated a good safety profile and the activation of a broad and specific immune response. However, these vaccines often demonstrated only modest therapeutic effects in clinical trials due to the immunosuppressive mechanisms developed by the tumor. To enhance the vaccine-induced immune response and the treatment efficacy, DNA vaccines could be improved by using two different strategies. The first is to increase their immunogenicity by selecting and optimizing the best antigen(s) to be inserted into the plasmid DNA. The second strategy is to combine DNA vaccines with other complementary therapies that could improve their activity by attenuating immunosuppression in the tumor microenvironment or by increasing the activity/number of immune cells. A growing number of preclinical and clinical studies are adopting these two strategies to better exploit the potential of DNA vaccination. In this review, we analyze the last 5-year preclinical studies and 10-year clinical trials using plasmid DNA vaccines for cancer therapy. We also investigate the strategies that are being developed to overcome the limitations in cancer DNA vaccination, revisiting the rationale for different combinations of therapy and the different possibilities in antigen choice. Finally, we highlight the most promising developments and critical points that need to be addressed to move towards the approval of therapeutic cancer DNA vaccines as part of the standard of cancer care in the future.

Concordance measure and discriminatory accuracy in transformation cure models

Many populations of early-stage cancer patients have non-negligible latent cure fractions that can be modeled using transformation cure models. However, there is a lack of statistical metrics to evaluate prognostic utility of biomarkers in this context due to the challenges associated with unknown cure status and heavy censorship. In this article, we develop general concordance measures as evaluation metrics for the discriminatory accuracy of transformation cure models including the so-called promotion time cure models and mixture cure models. We introduce explicit formulas for the consistent estimates of the concordance measures, and show that their asymptotically normal distributions do not depend on the unknown censoring distribution. The estimates work for both parametric and semiparametric transformation models as well as transformation cure models. Numerical feasibility of the estimates and their robustness to the censoring distributions are illustrated via simulation studies and demonstrated using a melanoma data set.

Impact of Polymer-TLR-7/8 Agonist (Adjuvant) Morphology on the Potency and Mechanism of CD8 T Cell Induction

Small molecule Toll-like receptor-7 and -8 agonists (TLR-7/8a) can be used as vaccine adjuvants to induce CD8 T cell immunity but require formulations that prevent systemic toxicity and focus adjuvant activity in lymphoid tissues. Here, we covalently attached TLR-7/8a to polymers of varying composition, chain architecture and hydrodynamic behavior (∼300 nm submicrometer particles, ∼10 nm micelles and ∼4 nm flexible random coils) and evaluated how these parameters of polymer-TLR-7/8a conjugates impact adjuvant activity in vivo. Attachment of TLR-7/8a to any of the polymer compositions resulted in a nearly 10-fold reduction in systemic cytokines (toxicity). Moreover, both lymph node cytokine production and the magnitude of CD8 T cells induced against protein antigen increased with increasing polymer-TLR-7/8a hydrodynamic radius, with the submicrometer particle inducing the highest magnitude responses. Notably, CD8 T cell responses induced by polymer-TLR-7/8a were dependent on CCR2+ monocytes and IL-12, whereas responses by a small molecule TLR-7/8a that unexpectedly persisted in vaccine-site draining lymph nodes (T1/2 = 15 h) had less dependence on monocytes and IL-12 but required Type I IFNs. This study shows how modular properties of synthetic adjuvants can be chemically programmed to alter immunity in vivo through distinct immunological mechanisms.

Vaccinia virus-mediated cancer immunotherapy: cancer vaccines and oncolytics

Cancer vaccines and oncolytic immunotherapy are promising treatment strategies with potential to provide greater clinical benefit to patients with advanced-stage cancer. In particular, recombinant vaccinia viruses (VV) hold great promise as interventional agents. In this article, we first summarize the current understanding of virus biology and viral genes involved in host-virus interactions to further improve the utility of these agents in therapeutic applications. We then discuss recent findings from basic and clinical studies using VV as cancer vaccines and oncolytic immunotherapies. Despite encouraging results gleaned from translational studies in animal models, clinical trials implementing VV vectors alone as cancer vaccines have yielded largely disappointing results. However, the combination of VV vaccines with alternate forms of standard therapies has resulted in superior clinical efficacy. For instance, combination regimens using TG4010 (MVA-MUC1-IL2) with first-line chemotherapy in advanced-stage non-small cell lung cancer or combining PANVAC with docetaxel in the setting of metastatic breast cancer have clearly provided enhanced clinical benefits to patients. Another novel cancer vaccine approach is to stimulate anti-tumor immunity via STING activation in Batf3-dependent dendritic cells (DC) through the use of replication-attenuated VV vectors. Oncolytic VVs have now been engineered for improved safety and superior therapeutic efficacy by arming them with immune-stimulatory genes or pro-apoptotic molecules to facilitate tumor immunogenic cell death, leading to enhanced DC-mediated cross-priming of T cells recognizing tumor antigens, including neoantigens. Encouraging translational and early phase clinical results with Pexa-Vec have matured into an ongoing global phase III trial for patients with hepatocellular carcinoma. Combinatorial approaches, most notably those using immune checkpoint blockade, have produced exciting pre-clinical results and warrant the development of innovative clinical studies. Finally, we discuss major hurdles that remain in the field and offer some perspectives regarding the development of next generation VV vectors for use as cancer therapeutics.

New treatment modalities with vaccine therapy in renal cell carcinoma

The aim of implementing vaccine therapy is to activate immune response against malignant cells by overcoming the tolerance triggered by the tumor. These treatments are effective using the immune response against cancer. Not every type of cancer is suitable for vaccine therapies. For a vaccine therapy to be implemented, cancer should be immunogenic and contain tissue-specific proteins, should have a slow progression, and treatments should be feasible. For that reason, studies regarding urological cancers are mostly focused on the kidneys and the prostate. Vaccine therapies used in renal cell carcinoma (RCC) can be categorized under the following titles: autologous tumor cells, dendritic cells, genetically modified tumor cells, and protein/peptide. Although there are old studies on the implementation of vaccine therapies in RCC, researches have only been intensified recently. In addition to their effective potential for lengthening general survival, decreasing tumor burden and cancer development in long term, vaccine treatments are especially effective in metastatic RCC patients. We think that vaccine treatments would be applied more in near future since RCC are immunogenic. In this compilation, we will discuss vaccine therapies used in RCC, which urologists are not so familiar with, in the light of the up-to-date literature.

Is It Possible to Develop Cancer Vaccines to Neoantigens, What Are the Major Challenges, and How Can These Be Overcome? Targeting the Right Antigens in the Right Patients

Recent advances in genomic sequencing and bioinformatics have empowered a revolution in immuno-oncology that has led to numerous unambiguous demonstrations of spontaneous and therapy-induced T-cell responses in patients against a subset of immunogenic tumor-specific somatic mutations known as neoantigens. These findings raise the exciting possibility that patients could be therapeutically treated with personalized vaccines against the mutations expressed by their own tumor. A central challenge for the broader clinical application of this approach will be to define the best antigens to target, to determine the subset of patients most likely to derive significant clinical benefit, and, finally, to discover both the best method of vaccine delivery and the optimal time in the disease course to do so. A growing number of translational immunologists believe that these challenges can be overcome and this perspective will discuss strategies to achieve this.

Local Phototherapy Synergizes with Immunoadjuvant for Treatment of Pancreatic Cancer through Induced Immunogenic Tumor Vaccine

Purpose: To develop a synergistic combination therapy for advanced pancreatic cancer, using local phototherapy and immunotherapy, and to determine the efficacy and mechanism of the novel combination therapy using a highly metastatic pancreatic tumor model in mice.Experimental Design: Mice bearing Panc02-H7 pancreatic tumors (both subcutaneous and orthotopic) were treated with noninvasive or interventional photothermal therapy, followed by local application of an immunoadjuvant. Tumor growth and animal survival were assessed. Immune cell populations within spleen and tumors were evaluated by FACS and IHC, and cytokine levels were determined by ELISA.Results: Up to 75% of mice bearing subcutaneous tumors treated with combination therapy had complete tumor regression. Local photothermal therapy exposed/released damage-associated molecular patterns, which initiated an immunogenic tumor cell death, resulting in infiltration of antigen-presenting cells and Th1 immunity. Concomitant application of immunoadjuvant amplified Th1 immunity, especially the tumor-specific cytotoxic T lymphocyte response, with increased quantity and quality of T cells. Combination therapy also induced tumor-specific immune memory, as demonstrated by resistance to tumor rechallenge and production of memory T cells. For the treatment of orthotopic tumor, the combination therapy significantly reduced the primary tumors and metastases, and prolonged the animal survival time.Conclusions: This study indicated that combination of local phototherapy and immunotherapy induced a systemic immunity against established tumors and metastases in an aggressive, preclinical pancreatic tumor model, leading to a potential clinical method for patients with advanced pancreatic cancer. Clin Cancer Res; 24(21); 5335-46. ©2018 AACR.

Polyclonal Rabbit Anti-Cancer-Associated Fibroblasts Globulins Induce Cancer Cells Apoptosis and Inhibit Tumor Growth

Cancer-associated fibroblasts (CAFs) constitute a major component of the tumor microenvironment. CAFs regulated the growth and development, invasion and metastasis of primary tumors, as well as response to treatment. Recent studies indicated that monoclonal antibody therapies had limited success, thus more effective polyclonal antibodies (Poly Abs) is urgently needed. Poly Abs is a possible alternative because they target multiple antigens simultaneously. In this report, we prepared Poly Abs by immunizing rabbits with the bFGF-activated fibroblasts. The Poly Abs inhibited the cancer cells proliferation as revealed by MTT analysis. The Poly Abs induced apoptosis as indicated by flow cytometric analysis, and microscopic observation of apoptotic changes in morphology. Compared with the control IgG, Poly Abs significantly inhibited tumor cells migration as indicated by wound healing and transwell analysis in vitro, and lung metastasis analysis in vivo. Serial intravenous injections of Poly Abs inhibited tumor growth in mice bearing murine CT26 colon carcinoma. Ki67 analysis indicated that Poly Abs significantly inhibited tumor cells proliferation, as compared to control Ig G treatments. Our findings suggested that Poly Abs was an effective agent for apoptosis induction, migration and metastasis inhibition. The Poly Abs may be useful as a safe anticancer agent for cancer immunotherapy in the future.

Sperm Protein 17 Expression by Murine Epithelial Ovarian Cancer Cells and Its Impact on Tumor Progression

The cancer testis antigen sperm protein 17 (Sp17) is a promising antigenic target in epithelial ovarian cancer (EOC) vaccine development. However, its role in ovarian cancer is unclear. We isolated and expanded Sp17⁺ and Sp17⁻ clones from the murine EOC cell line ID8, and compared their in-vitro cell growth characteristics and in-vivo tumorigenicity. We also examined the potential co-expression of molecules that may influence cancer cell survival and interaction with immune cells. These include stimulatory and immunosuppressive molecules, such as major histocompatibility class I molecules (MHC I), MHC II, cytotoxic T lymphocyte associated antigen-4 (CTLA-4), CD73, CD39, tumor necrosis factor receptor II (TNFRII), signal transducer and activator of transcription 3 (STAT3) and programmed death-ligand 1 (PD-L1). Whilst the presence of Sp17 was not correlated with the ID8 cell proliferation/growth capacity in vitro, it was critical to enable progressive tumor formation in vivo. Flow cytometry revealed that Sp17⁺ ID8 cells displayed higher expression of both STAT3 and PD-L1, whilst MHC II expression was lower. Moreover, Sp17^high (PD-L1⁺MHCII⁻) cell populations showed significantly enhanced resistance to Paclitaxel-induced cell death in vitro compared to Sp17^low (PD-L1⁻MHCII⁺) cells, which was associated in turn with increased STAT3 expression. Together, the data support Sp17 as a factor associated with in-vivo tumor progression and chemo-resistance, validating it as a suitable target for vaccine development.

Technical Feasibility of Tissue Microarray (TMA) Analysis of Tumor-Associated Immune Response in Prostate Cancer

Introduction: The androgen receptor (AR) regulates immune-related epithelial-to-mesenchymal transition (EMT), and prostate cancer (PCa) metastasis. Primary tumor-infiltrating lymphocytes (TILs) [CD3⁺, CD4⁺, and CD8⁺ TILs] are potential prognostic indicators in PCa, and variations may contribute to racial disparities in tumor biology and PCa outcomes.

Aim: To assess the technical feasibility of tumor microarray (TMA)-based methods to perform multi-marker TIL profiling in primary resected PCa.

Methods: Paraffin-embedded tissue cores of histopathologically-confirmed primary PCa (n = 40; 1 TMA tissue specimen loss) were arrayed in triplicate on TMAs. Expression profiles of AR, CD3⁺, CD4⁺, and CD8⁺ TILs in normal prostate, and the center and periphery of both the tumor-dominant nodule and highest Gleason grade were detected by IHC and associated with clinical and pathological data using standard statistical methodology. An independent pathologist, blinded to the clinical data, scored all samples (percent and intensity of positive cells).

Results: TMAs were constructed from 21 (53.8%) Black and 18 (46.2%) White males with completely-resected, primarily pT2 stage PCa [pT2a (n = 3; 7.7%); pT2b (n = 2; 5.1%); pT2c (n = 27; 69.2%); pT3a (n = 5; 12.8%); mean pre-op PSA = 8.17 ng/ml]. The CD3, CD4, CD8, and CD8/CD3 cellular protein expression differed from normal in the periphery of the dominant nodule, the center of the highest Gleason grade, and the periphery of the highest Gleason grade (P < 0.05). Correlations between TIL expression in the center and periphery of the dominant nodule, with corresponding center and periphery of the highest Gleason grade, respectively, were robust, and the magnitude of these correlations differed markedly by race (P < 0.05).

Conclusions: Multi-marker (AR, CD3, CD4, CD8) profiling with IHC analysis of TMAs consisting of primary, non-metastatic resected prostate cancer is technically feasible in this pilot study. Future studies will evaluate primary tumor immunoscore using semi-quantitative, IHC-based methodology to assess differences in the spectrum, quantity, and/or localization of TILs, and to gain insights into racial disparities in PCa tumor biology and clinical outcomes.

Quantitative T-cell repertoire analysis of peripheral blood mononuclear cells from lung cancer patients following long-term cancer peptide vaccination

Therapeutic cancer peptide vaccination is an immunotherapy designed to elicit cytotoxic T-lymphocyte (CTL) responses in patients. A number of therapeutic vaccination trials have been performed, nevertheless there are only a few reports that have analyzed the T-cell receptors (TCRs) expressed on tumor antigen-specific CTLs. Here, we use next-generation sequencing (NGS) to analyze TCRs of vaccine-induced CTL clones and the TCR repertoire of bulk T cells in peripheral blood mononuclear cells (PBMCs) from two lung cancer patients over the course of long-term vaccine therapy. In both patients, vaccination with two epitope peptides derived from cancer/testis antigens (upregulated lung cancer 10 (URLC10) and cell division associated 1 (CDCA1)) induced specific CTLs expressing various TCRs. All URLC10-specific CTL clones tested showed Ca2+ influx, IFN-γ production, and cytotoxicity when co-cultured with URLC10-pulsed tumor cells. Moreover, in CTL clones that were not stained with the URLC10/MHC-multimer, the CD3 ζ chain was not phosphorylated. NGS of the TCR repertoire of bulk PBMCs demonstrated that the frequency of vaccine peptide-specific CTL clones was near the minimum detectable threshold level. These results demonstrate that vaccination induces antigen-specific CTLs expressing various TCRs at different time points in cancer patients, and that some CTL clones are maintained in PBMCs during long-term treatment, including some with TCRs that do not bind peptide/MHC-multimer.

Immunotherapy for metastatic prostate cancer: immuno-cold or the tip of the iceberg?

PURPOSE OF REVIEW

Metastatic castration-resistant prostate cancer is in critical need of new and innovative treatment strategies. Since the approval of sipuleucel-T, the investigatory climate of prostate cancer immunotherapy has been rapidly evolving with promising developments in vaccine and immune checkpoint therapies.

RECENT FINDINGS

Sipuleucel-T remains the first and only therapeutic cancer vaccine approved for its survival benefit in metastatic castration-resistant prostate cancer. Additional cancer vaccines are currently being evaluated, with the most promising being a peptide vaccine encoding prostate-specific antigen, known as prostate-specific antigen-TRICOM. Emerging data supports combinatorial strategies for vaccine therapy and a potential role for implementation in earlier stages of advanced disease. Immune checkpoint therapies have demonstrated limited success in prostate cancer with negative late phase trials for ipilimumab monotherapy and discouraging early phase results for programmed cell death protein 1 blockade. Novel immune-modulatory targets and rational combination strategies aim to produce more favorable results. Recent progress has been made to determine biologic predictors for response and toxicity in prostate cancer immunotherapy aiming to improve patient selection and safety.

SUMMARY

Steady progress is anticipated in the field of prostate cancer immunotherapy including ongoing development of novel cancer vaccines, immune checkpoint therapies, and combinatorial strategies.