Peptide-Based Vaccination and Induction of CD8+ T-Cell Responses Against Tumor Antigens in Breast Cancer

Oral Administration of Cancer Vaccines: Challenges and Future Perspectives

Cancer vaccines, a burgeoning strategy in cancer treatment, are exploring innovative administration routes to enhance patient and medical staff experiences, as well as immunological outcomes. Among these, oral administration has surfaced as a particularly noteworthy approach, which is attributed to its capacity to ignite both humoral and cellular immune responses at systemic and mucosal tiers, thereby potentially bolstering vaccine efficacy comprehensively and durably. Notwithstanding this, the deployment of vaccines through the oral route in a clinical context is impeded by multifaceted challenges, predominantly stemming from the intricacy of orchestrating effective oral immunogenicity and necessitating strategic navigation through gastrointestinal barriers. Based on the immunogenicity of the gastrointestinal tract, this review critically analyses the challenges and recent advances and provides insights into the future development of oral cancer vaccines.

Recent advances in tumor biomarker detection by lanthanide upconversion nanoparticles

Early tumor diagnosis could reliably predict the behavior of tumors and significantly reduce their mortality. Due to the response to early cancerous changes at the molecular or cellular level, tumor biomarkers, including small molecules, proteins, nucleic acids, exosomes, and circulating tumor cells, have been employed as powerful tools for early cancer diagnosis. Therefore, exploring new approaches to detect tumor biomarkers has attracted a great deal of research interest. Lanthanide upconversion nanoparticles (UCNPs) provide numerous opportunities for bioanalytical applications. When excited by low-energy near-infrared light, UCNPs exhibit several unique properties, such as large anti-Stoke shifts, sharp emission lines, long luminescence lifetimes, resistance to photobleaching, and the absence of autofluorescence. Based on these excellent properties, UCNPs have demonstrated great sensitivity and selectivity in detecting tumor biomarkers. In this review, an overview of recent advances in tumor biomarker detection using UCNPs has been presented. The key aspects of this review include detection mechanisms, applications in vitro and in vivo, challenges, and perspectives of UCNP-based tumor biomarker detection.

Insight into the Prospects for Tumor Therapy Based on Photodynamic Immunotherapy

Malignancy is one of the common diseases with high mortality worldwide and the most important obstacle to improving the overall life expectancy of the population in the 21st century. Currently, single or combined treatments, including surgery, chemotherapy, and radiotherapy, are still the mainstream regimens for tumor treatment, but they all present significant side effects on normal tissues and organs, such as organ hypofunction, energy metabolism disorders, and various concurrent diseases. Based on this, theranostic measures for the highly selective killing of tumor cells have always been a hot area in cancer-related fields, among which photodynamic therapy (PDT) is expected to be an ideal candidate for practical clinical application due to its precise targeting and excellent safety performance, so-called PDT refers to a therapeutic method mainly composed of photosensitizers (PSs), laser light, and reactive oxygen species (ROS). Photoimmunotherapy (PIT), a combination of PDT and immunotherapy, can induce systemic antitumor immune responses and inhibit continuing growth and distant metastasis of residual tumor cells, demonstrating a promising application prospect. This article reviews the types of immune responses that occur in the host after PDT treatment, including innate and adaptive immunity. To further help PIT-related drugs improve their pharmacokinetic properties and bioavailability, we highlight the potential improvement of photodynamic immunotherapy from three aspects: immunostimulatory agents, tumor-associated antigens (TAAs) as well as different immune cells. Finally, we focus on recent advances in various strategies and shed light on their corresponding mechanisms of immune activation and possible clinical applications such as cancer vaccines. Having discovered the inherent potential of PDT and the mechanisms that PDT triggers host immune responses, a variety of immunotherapeutic strategies have been investigated in parallel with approaches to improve PDT efficiency. However, it remains to be further elucidated under what conditions the immune effect induced by PDT can achieve tumor immunosuppression and to what extent PDT-induced antitumor immunity will lead to complete tumor rejection. Currently, PIT presents several outstanding intractable challenges, such as the aggregation ability of PSs locally in tumors, deep tissue penetration ability of laser light, immune escape, and biological toxicity, and it is hoped that these issues raised will help to point out the direction of preclinical research on PIT and accelerate its transition to clinical practice.

Companion Animal Model in Translational Oncology; Feline Oral Squamous Cell Carcinoma and Canine Oral Melanoma

Simple Summary

Laboratory rodents are the most common animal models used in preclinical cancer research. Companion animals with naturally occurring cancers are an under-utilized natural model for the development of new anti-cancer drugs. Dogs and cats develop several types of cancers that resemble those arising in humans with similar clinical and histopathological features and often with similar molecular and genetic backgrounds. Exposure to environmental carcinogens, including air, food and water are also common between people and their pets. Dogs and cats are a unique model that could be integrated between the preclinical laboratory animal model and human clinical trials.

Abstract

Companion animals with naturally occurring cancers can provide an advantageous model for cancer research and in particular anticancer drug development. Compared to commonly utilized mouse models, companion animals, specifically dogs and cats, share a closer phylogenetical distance, body size, and genome organization. Most importantly, pets develop spontaneous, rather than artificially induced, cancers. The incidence of cancer in people and companion animals is quite similar and cancer is the leading cause of death in dogs over 10 years of age. Many cancer types in dogs and cats have similar pathological, molecular, and clinical features to their human counterparts. Drug toxicity and response to anti-cancer treatment in dogs and cats are also similar to those in people. Companion animals share their lives with their owners, including the environmental and socioeconomic cancer-risk factors. In contrast to humans, pets have a shorter life span and cancer progression is often more rapid. Clinical trials in companion animals are cheaper and less time consuming compared to human trials. Dogs and cats with naturally occurring cancers are an ideal and unique model for human cancer research. Model selection for the specific type of cancer is of pivotal importance. Although companion animal models for translational research have been reviewed previously, this review will try to summarize the most important advantages and disadvantages of this model. Feline oral squamous cell carcinoma as a model for head and neck squamous cell carcinoma and canine oral melanoma as a model for mucosal melanoma and immunotherapy in people will be discussed as examples.

AE37: a HER2-targeted vaccine for the prevention of breast cancer recurrence

INTRODUCTION

HER2 is a prevalent growth factor in a variety of malignancies, most prominently breast cancer. Over-expression has been correlated with the poorest overall survival and has been the target of successful therapies such as trastuzumab. AE37 is a novel, HER2-directed vaccine based on the AE36 hybrid peptide (aa776-790), which is derived from the intracellular portion of the HER2 protein, and the core portion of the MHC Class II invariant chain (the Ii-Key peptide). This hybrid peptide is given with GM-CSF immunoadjuvant as the AE37 vaccine.

AREAS COVERED

This article describes in detail the preclinical science leading to the creation of the AE37 vaccine and examines use of this agent in multiple clinical trials for breast and prostate cancer. The safety profile of AE37 is discussed and opinions on the potential of the vaccine in breast and prostate cancer patient subsets along with other malignancies, are offered.

EXPERT OPINION

Future trials utilizing the AE37 vaccine to treat other HER2-expressing malignancies are likely to see similar success, and this will be enhanced by combination immunotherapy. Ii-Key modification of other peptides of interest across oncology and virology could yield impressive results over the longer term.

Using lymph node swelling as a potential biomarker for successful vaccination

There is currently a lack of biomarkers to help properly assess novel immunotherapies at both the preclinical and clinical stages of development. Recent work done by our group indicated significant volume changes in the vaccine draining right lymph node (RLN) volumes of mice that had been vaccinated with DepoVaxTM, a lipid-based vaccine platform that was developed to enhance the potency of peptide-based vaccines. These changes in lymph node (LN) volume were unique to vaccinated mice.To better assess the potential of volumetric LN markers for multiple vaccination platforms, we evaluated 100 tumor bearing mice and assessed their response to vaccination with either a DepoVax based vaccine (DPX) or a water-in-oil emulsion (w/o), and compared them to untreated controls. MRI was used to longitudinally monitor LN and tumor volumes weekly over 4 weeks. We then evaluated changes in LN volumes occurring in response to therapy as a potential predictive biomarker for treatment success.We found that for both vaccine types, DPX and w/o, the %RLN volumetric increase over baseline and the ratio of RLN/LLN were strong predictors of successful tumor suppression (LLN is left inguinal LN). The area under the curve (AUC) was greatest, between 0.75-0.85, two (%RLN) or three (RLN/LLN) weeks post-vaccination. For optimized critical thresholds we found these biomarkers consistently had sensitivity >90% and specificity >70% indicating strong prognostic potential. Vaccination with DepoVax had a more pronounced effect on draining lymph nodes than w/o emulsion vaccines, which correlated with a higher anti-tumor activity in DPX-treated mice.

Adaptive immunity programmes in breast cancer

The role of the immune system in shaping cancer development and patient prognosis has recently become an area of intense focus in industry and academia. Harnessing the adaptive arm of the immune system for tumour eradication has shown great promise in a variety of tumour types. Differences between tissues, however, necessitate a greater understanding of the adaptive immunity programmes that are active within each tumour type. In breast cancer, adaptive immune programmes play diverse roles depending on the cellular infiltration found in each tumour. Cytotoxic T lymphocytes and T helper type 1 cells can induce tumour eradication, whereas regulatory T cells and T helper type 2 cells are known to be involved in tumour-promoting immunosuppressive responses. Complicating these matters, heterogeneous expression of hormone receptors and growth factors in different tumours leads to disparate, patient-specific adaptive immune responses. Despite this non-conformity in adaptive immune behaviours, encouraging basic and clinical results have been observed that suggest a role for immunotherapeutic approaches in breast cancer. Here, we review the literature pertaining to the adaptive immune response in breast cancer, summarize the primary findings relating to the breast tumour's biology, and discuss potential clinical immunotherapies.

Inhibition of tumor growth and metastasis by EMMPRIN multiple antigenic peptide (MAP) vaccination is mediated by immune modulation

Previously, we have identified a new epitope in EMMPRIN, a multifunctional protein that mediates tumor cell-macrophage interactions and induces both MMP-9 and VEGF. Here, we synthesized this epitope as an octa-branched multiple antigenic peptide (MAP) to vaccinate mice implanted with subcutaneous syngeneic colon (CT26), prostate (TRAMP-C2) or renal (RENCA) cell line carcinomas. Vaccination inhibited, and sometimes regressed, tumor growth in a dose-dependent manner, reaching 94%, 71% and 72% inhibition, respectively, at a 50 μg dose (p < 0.01). Mice with regressed tumors demonstrated immune memory, preventing tumor recurrence upon re-implantation (p < 0.001). When tumor cells were administered through the tail vein to generate lung metastases, vaccination reduced the number of metastatic foci (by 15- and 23-folds, p < 0.001), and increased the median survival time by 25% and 53% in RENCA and CT26 metastases, respectively (p < 0.01) relative to scrambled-MAP controls. No significant adverse responses were observed in all experiments. We show that the tumor microenvironment was immune modulated, as vaccination induced production of EMMPRIN-specific antibodies, increased CD8⁺ T cells infiltration and cytotoxicity, alleviated immune suppression by decreasing TGFβ concentrations, reduced angiogenesis and cell proliferation, and enhanced apoptosis. Thus, our successful active peptide vaccination strategy differs from previous, unsuccessful attempts, both in the selected target (the EMMPRIN epitope) and in the use of a modified, MAP configuration, and demonstrates that this may be an efficient approach for the treatment and prevention of some types of cancer.

Immunotherapy in breast cancer: An overview of modern checkpoint blockade strategies and vaccines

Immune therapy has recently emerged as a standard-of-care strategy for the treatment of melanoma, lung cancer, bladder cancer, among other malignancies. However, the role of immune therapy in the treatment of breast cancer is still being determined. Two current strategies for harnessing the immune system to treat cancer include drugs that modulate key T cell inhibitory checkpoints and vaccines. Specifically, modern immune therapy strategies can facilitate T-cell mediated tumor regression by priming the immune system against specific tumor associated antigens, by modulating immunoregulatory signals, or both. In breast cancer, preliminary data from preclinical and early clinical studies are promising. In fact, clinical data with checkpoint blockade as monotherapy has been reported in multiple breast cancer subtypes to date, with durable responses observed in a significant proportion of women with chemotherapy resistant disease. However, because the number of genetic mutations and thus, the number of neoantigens available for immune response are modest in most breast cancers when compared with other cancers, most breast cancers may not be inherently sensitive to immune modulation and therefore may require strategies that enhance tumor associated antigen presentation if immune modulation strategies are to be effective. To that end, studies that combine checkpoint blockade with other strategies including established systemic therapies (including hormone therapy and chemotherapy), radiation therapy, and localized therapy including tumor freezing (cryoablation) are underway in breast cancer. Studies that combine checkpoint blockade with vaccines are also planned. Herein, we provide a brief summary of key components of the immune response against cancer, a rationale for the use of immune therapy in breast cancer, data from early clinical trials of checkpoint blockade and vaccine strategies in breast cancer, and future directions in the field.

HLAsupE: an integrated database of HLA supertype-specific epitopes to aid in the development of vaccines with broad coverage of the human population

Background

Promiscuous T-cell epitopes that can be presented by multiple human leukocyte antigens (HLAs) are prime targets for vaccine and immunotherapy development because they are effective in a high proportion of the human population. Although there are a number of epitope databases currently available online, the epitope data in these databases were annotated using specific MHC restrictions, and none of these databases was specifically designed for retrieving data on promiscuous epitopes.

Description

HLAsupE is an integrated database of HLA supertype-specific epitopes (promiscuous T-cell epitopes in the context of HLA supertypes). The source data for the T-cell activities and HLA-binding capacities of peptides with a specific HLA restriction were extracted from public epitope databases. After a manual curation, these allele-specific data were integrated into supertype-specific datasets based on the defined supertypes and corresponding alleles. Each supertype-specific peptide in HLAsupE is annotated in terms of its cross-reactivity to HLA molecules within the same supertype. Promiscuous peptides that can be presented by multiple HLA molecules across multiple HLA supertypes were also included in this database. Several web-based tools are provided to access and download the data.

Conclusions

HLAsupE is the first database of promiscuous T cell epitopes that is organized based on the HLA supertypes. The main advantage of this database is the ability to search for promiscuous T-cell epitopes based on the cross-reactivity to specific alleles or supertypes. HLAsupE will be a valuable resource for the development of epitope-based vaccines and immunotherapies with broad coverage of human population.

CpG-mediated augmentation of CD8+ T-cell responses in mice is attenuated by a water-in-oil emulsion (Montanide ISA-51) but enhanced by an oil-in-water emulsion (IDRI SE)

Adjuvants are a key component in enhancing immunogenicity of vaccines and play a vital role in facilitating the induction of the correct type of immunity required for each vaccine to be optimally efficacious. Several different adjuvants are found in licensed vaccines, and many others are in pre-clinical or clinical testing. Agonists for TLRs are potent activators of the innate immune system and some, such as CpG (TLR9 agonist), are particularly good for promoting cellular immunity because of the induction of Th1 cytokines. Emulsions that have both delivery and adjuvant properties are classified as water-in-oil (W/O) or oil-in-water (O/W) formulations. The W/O emulsion Montanide ISA-51, often combined with CpG, has been widely tested in cancer vaccine clinical trials. Squalene-based O/W emulsions are in licensed influenza vaccines, and T-cell responses have been assessed pre-clinically. No clinical study has compared the two types of emulsions, and the continued use of W/O with CpG in cancer vaccines may be because the lack of single adjuvant controls has masked the interference issue. These findings may have important implications for the development of vaccines where T-cell immunity is considered essential, such as those for cancer and chronic infections. Using particulate (hepatitis B surface antigen) and soluble protein (ovalbumin) antigen, we show in mice that a W/O emulsion (ISA-51) abrogates CpG-mediated augmentation of CD8(+) T-cell responses, whereas a squalene-based O/W emulsion significantly enhanced them.

Tumour-associated antigens and their anti-cancer applications

So far, a number of tumour-associated antigens (TAAs), such as heat shock proteins, alpha-fetoprotein, carcino-embryonic antigen and others have been identified in a variety of malignant tumours. Differences in the expression levels of TAAs in cancers compared with normal cells have led to these antigens being investigated as diagnostic and prognostic biomarkers or exciting targets in cancer treatment. Here, we systematically list the current representative TAAs to shed some light on current approaches and challenges for their anti-cancer application in cancer therapy. In this review, we discuss the ongoing pre-clinical studies and clinical development of TAAs in human cancers, and the potential application of these TAAs in the diagnosis and prognosis for cancer treatment.