MHC class II tetramer analyses in AE37-vaccinated prostate cancer patients reveal vaccine-specific polyfunctional and long-lasting CD4(+) T-cells

MHC tetramer technology: Exploring T cell biology in health and disease

Major histocompatibility complex (MHC) tetramers stand as formidable tools within T cell biology, facilitating the exploration and comprehension of immune responses. These artificial molecules, comprising four bound MHC molecules, typically with a specified peptide and a fluorescent label, play a pivotal role in characterizing T cell subsets, monitoring clonal expansion, and unraveling T cell dynamics during responses to infections or immunotherapies. Beyond their applications in T cell biology, MHC tetramers prove valuable in investigating a spectrum of diseases such as infectious diseases, autoimmune disorders, and cancers. Their instrumental role extends to vaccine research and development. Notably, when appropriately configured, tetramers transcend T cell biology research and find utility in exploring natural killer T cells and contributing to specific T cell clonal deletions.

AE37 HER2-targeted vaccine in the prevention of breast cancer recurrence: A mini narrative review of current evidence

Breast cancer remains a significant global health challenge, necessitating innovative therapeutic strategies. This review synthesizes findings from multiple studies investigating the safety profile and efficacy of the AE37 human epidermal growth factor receptor 2 (HER2)-targeted vaccine, offering insights into its potential role in breast cancer immunotherapy. A systematic search of electronic databases, including PubMed, MEDLINE, Scopus, and Web of Science, was conducted to identify relevant articles published up to October 2023. The search strategy utilized a combination of keywords, including "AE37 HER2 vaccine," "breast cancer recurrence prevention," and related terms. Boolean operators (AND, OR) were employed to refine the search. The AE37 vaccine exhibited a favorable safety profile across all studies, with minimal adverse effects reported. Efficacy outcomes varied, with promising trends observed in specific breast cancer subgroups, such as advanced-stage, HER2 under-expressed, and triple-negative breast cancer patients. Subgroup analyses suggested potential benefits, emphasizing the need for precise patient stratification. While the AE37 HER2-targeted vaccine demonstrates a promising safety profile and potential efficacy in specific breast cancer subgroups, an understanding requires addressing identified limitations and advancing research in nuanced directions. This paper provides a foundation for navigating the complex landscape of breast cancer immunotherapy with the AE37 vaccine.

Tumor vaccines: Toward multidimensional anti-tumor therapies

For decades, immunotherapies have offered hope for patients with advanced cancer. However, they show distinct benefits and limited clinical effects. Tumor vaccines have the potential to prime tumor-antigen-specific T cells and induce broad subsets of immune responses, ultimately eradicating tumor cells. Here, we classify tumor vaccines by their anti-tumor mechanisms, which include boosting the immune system, overcoming tumor immunosuppression, and modulating tumor angiogenesis. We focus on multidimensional tumor vaccine strategies using combinations of two or three of the above mechanisms, as these are superior to single-dimensional treatments. This review offers a perspective on tumor vaccine strategies and the future role of vaccine therapies in cancer treatment.

Bidirectional crosstalk between therapeutic cancer vaccines and the tumor microenvironment: Beyond tumor antigens

Immunotherapy has rejuvenated cancer therapy, especially after anti-PD-(L)1 came onto the scene. Among the many therapeutic options, therapeutic cancer vaccines are one of the most essential players. Although great progress has been made in research on tumor antigen vaccines, few phase III trials have shown clinical benefits. One of the reasons lies in obstruction from the tumor microenvironment (TME). Meanwhile, the therapeutic cancer vaccine reshapes the TME in an ambivalent way, leading to immune stimulation or immune escape. In this review, we summarize recent progress on the interaction between therapeutic cancer vaccines and the TME. With respect to vaccine resistance, innate immunosuppressive TME components and acquired resistance caused by vaccination are both involved. Understanding the underlying mechanism of this crosstalk provides insight into the treatment of cancer by directly targeting the TME or synergizing with other therapeutics.

The Prognostic Significance of Selected HLA Alleles on Prostate Cancer Outcome

Recently, we have shown that HLA-A*02:01 and HLA-A*24:02 in de novo metastatic prostate cancer (MPCa) have an important role in disease progression. Since de novo MPCa represents a small group among patients diagnosed with prostate cancer (PCa), it was obvious to try to extend the validity of our results to larger cohorts of PCa patients. Herein, we analyzed patients irrespective of their disease status at diagnosis to include, besides patients with MPCa, those with localized PCa (LPCa). Our goal was to specify the prognostic value of HLA-A*02:01 and HLA-A*24:02 for overall survival (OS) prospectively and for early biochemical recurrence (BCR) and castrate resistance (CR) as additional clinical endpoints in a prospective/retrospective manner, to improve clinical decisions for patients covering all stages of PCa. On univariate analysis, HLA-A alleles were significantly associated as prognostic biomarkers with early BCR (p = 0.028; HR = 1.822), OS (p = 0.013; HR = 1.547) and showed a trend for CR (p = 0.150; HR = 1.239). On multivariate analysis, HLA-A alleles proved to be independent prognosticators for early BCR (p = 0.017; HR = 2.008), CR (p = 0.005; HR = 1.615), and OS (p = 0.002; HR = 2.063). Kaplan-Meier analyses revealed that patients belonging to the HLA-A*02:01+HLA-A*24:02- group progressed much faster to BCR and CR and had also shorter OS compared to HLA-A*24:02+ patients. Patients being HLA-A*02:01-HLA-A*24:02- exhibited varying clinical outcomes, pointing to the presence of additional HLA-A alleles with potential prognostic value. Our data underline the HLA-A alleles as valuable prognostic biomarkers for PCa that may assist with the appropriate treatment and follow-up schedule based on the risk for disease progression to avoid over-diagnosis and over-treatment.

Frequencies of an Immunogenic HER-2/neu Epitope of CD8+ T Lymphocytes Predict Favorable Clinical Outcomes in Prostate Cancer

HER-2/neu is the human epidermal growth factor receptor 2, which is associated with the progression of prostate cancer (PCa). HER-2/neu-specific T cell immunity has been shown to predict immunologic and clinical responses in PCa patients treated with HER-2/neu peptide vaccines. However, its prognostic role in PCa patients receiving conventional treatment is unknown, and this was addressed in this study. The densities of CD8+ T cells specific for the HER-2/neu_(780-788) peptide in the peripheral blood of PCa patients under standard treatments were correlated with TGF-β/IL-8 levels and clinical outcomes. We demonstrated that PCa patients with high frequencies of HER-2/neu_(780-788)-specific CD8+ T lymphocytes had better progression-free survival (PFS) as compared with PCa patients with low frequencies. Increased frequencies of HER-2/neu_(780-788)-specific CD8+ T lymphocytes were also associated with lower levels of TGF-β and IL-8. Our data provide the first evidence of the predictive role of HER-2/neu-specific T cell immunity in PCa.

The Era of Cytotoxic CD4 T Cells

In 1986, Mosmann and Coffman identified 2 functionally distinct subsets of activated CD4 T cells, Th1 and Th2 cells, being key in distinct T cell mediated responses. Over the past three decades, our understanding of CD4 T cell differentiation has expanded and the initial paradigm of a dichotomic CD4 T cell family has been revisited to accommodate a constantly growing number of functionally distinct CD4 T helper and regulatory subpopulations. Of note, CD4 T cells with cytotoxic functions have also been described, initially in viral infections, autoimmune disorders and more recently also in cancer settings. Here, we provide an historical overview on the discovery and characterization of cytotoxic CD4 T cells, followed by a description of their mechanisms of cytotoxicity. We emphasize the relevance of these cells in disease conditions, particularly in cancer, and we provide insights on how to exploit these cells in immunotherapy.

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.

SITC cancer immunotherapy resource document: a compass in the land of biomarker discovery

Since the publication of the Society for Immunotherapy of Cancer's (SITC) original cancer immunotherapy biomarkers resource document, there have been remarkable breakthroughs in cancer immunotherapy, in particular the development and approval of immune checkpoint inhibitors, engineered cellular therapies, and tumor vaccines to unleash antitumor immune activity. The most notable feature of these breakthroughs is the achievement of durable clinical responses in some patients, enabling long-term survival. These durable responses have been noted in tumor types that were not previously considered immunotherapy-sensitive, suggesting that all patients with cancer may have the potential to benefit from immunotherapy. However, a persistent challenge in the field is the fact that only a minority of patients respond to immunotherapy, especially those therapies that rely on endogenous immune activation such as checkpoint inhibitors and vaccination due to the complex and heterogeneous immune escape mechanisms which can develop in each patient. Therefore, the development of robust biomarkers for each immunotherapy strategy, enabling rational patient selection and the design of precise combination therapies, is key for the continued success and improvement of immunotherapy. In this document, we summarize and update established biomarkers, guidelines, and regulatory considerations for clinical immune biomarker development, discuss well-known and novel technologies for biomarker discovery and validation, and provide tools and resources that can be used by the biomarker research community to facilitate the continued development of immuno-oncology and aid in the goal of durable responses in all patients.

HLA Class I Allele Expression and Clinical Outcome in De Novo Metastatic Prostate Cancer

The prognostic value of human leukocyte antigen (HLA) class I molecules in prostate cancer (PCa) remains unclear. Herein, we investigated the prognostic relevance of the most frequently expressed HLA-A alleles in Greece (A*02:01 and HLA-A*24:02) in de novo metastatic hormone-sensitive PCa (mPCa), which is a rare and aggressive disease characterized by a rapid progression to castration-resistance (CR) and poor overall survival (OS), contributing to almost 50% of PCa-related deaths. We identified 56 patients who had either progressed to CR (these patients were retrospectively analyzed for the time to the progression of CR and prospectively for OS) or had at least three months’ follow-up postdiagnosis without CR progression and, thus, were prospectively analyzed for both CR and OS. Patients expressing HLA-A*02:01 showed poor clinical outcomes vs. HLA-A*02:01⁻negative patients. HLA-A*24:02⁻positive patients progressed slower to CR and had increased OS. Homozygous HLA-A*02:01 patients progressed severely to CR, with very short OS. Multivariate analyses ascribed to both HLA alleles significant prognostic values for the time to progression (TTP) to CR and OS. The presence of HLA-A*02:01 and HLA-A*24:02 alleles in de novo mPCa patients are significantly and independently associated with unfavorable or favorable clinical outcomes, respectively, suggesting their possible prognostic relevance for treatment decision-making in the context of precision medicine.

Single-Cell Multiplexed Proteomics on the IsoLight Resolves Cellular Functional Heterogeneity to Reveal Clinical Responses of Cancer Patients to Immunotherapies

Cancer immunotherapies, in particular adoptive T cell therapy and immune-checkpoint blockade therapy have demonstrated a remarkable success in the treatment of cancer. However, due to heterogeneous functionality and complex immune response of immune cells, it remains challenging to identify predictive biomarkers which have the potential to correlate with efficacy and adverse effects of immunotherapies and help selecting patients who might benefit from the therapy, developing more personalized therapeutics as well as reducing clinical trial cost. The single-cell IsoCode chip in conjunction with fluorescent ELISA-based assay enables a simultaneous detection up to 40+ proteins secreted from live single immune cells, providing a large portion of the assayable functions for each immune cell type, and thus precise assessment of multifunctional, or polyfunctional, heterogeneity of each immune cell type.This unique functional detection capability provides a powerful solution to unmet needs in immunotherapy patient profiling today. Recently, the single-cell metric termed polyfunctional strength index (PSI™) by IsoCode chip computed from preinfusion anti-CD19 chimeric antigen receptor (CAR)-T cell products has demonstrated a significant association with clinical response and cytokine release syndrome (CRS) of cancer patient to the therapy after cell product infusion. This chapter elucidates IsoPlexis single-cell highly multiplexed proteomic platform and provides technical details for characterizing cell products and various cell subsets from peripheral blood, bone marrow, or tumor tissues using this assay.

Striking a Balance-Cellular and Molecular Drivers of Memory T Cell Development and Responses to Chronic Stimulation

Effective adaptive immune responses are characterized by stages of development and maturation of T and B cell populations that respond to disturbances in the host homeostasis in cases of both infections and cancer. For the T cell compartment, this begins with recognition of specific peptides by naïve, antigen-inexperienced T cells that results in their activation, proliferation, and differentiation, which generates an effector population that clears the antigen. Loss of stimulation eventually returns the host to a homeostatic state, with a heterogeneous memory T cell population that persists in the absence of antigen and is primed for rapid responses to a repeat antigen exposure. However, in chronic infections and cancers, continued antigen persistence impedes a successful adaptive immune response and the formation of a stereotypical memory population of T cells is compromised. With repeated antigen stimulation, responding T cells proceed down an altered path of differentiation that allows for antigen persistence, but much less is known regarding the heterogeneity of these cells and the extent to which they can become “memory-like,” with a capacity for self-renewal and recall responses that are characteristic of bona fide memory cells. This review focuses on the differentiation of CD4⁺ and CD8⁺ T cells in the context of chronic antigen stimulation, highlighting the central observations in both human and mouse studies regarding the differentiation of memory or “memory-like” T cells. The importance of both the cellular and molecular drivers of memory T cell development are emphasized to better understand the consequences of persisting antigen on T cell fates. Integrating what is known and is common across model systems and patients can instruct future studies aimed at further understanding T cell differentiation and development, with the goal of developing novel methods to direct T cells toward the generation of effective memory populations.

CD8+ T-cell mediated anti-malaria protection induced by malaria vaccines; assessment of hepatic CD8+ T cells by SCBC assay

Malaria is a severe infectious disease with relatively high mortality, thus having been a scourge of humanity. There are a few candidate malaria vaccines that have shown a protective efficacy in humans against malaria. One of the candidate human malaria vaccines, which is based on human malaria sporozoites and called PfSPZ Vaccine, has been shown to protect a significant proportion of vaccine recipients from getting malaria. PfSPZ Vaccine elicits a potent response of hepatic CD8+ T cells that are specific for malaria antigens in non-human primates. To further characterize hepatic CD8+ T cells induced by the sporozoite-based malaria vaccine in a mouse model, we have used a cutting-edge Single-cell Barcode (SCBC) assay, a recently emerged approach/method for investigating the nature of T-cells responses during infection or cancer. Using the SCBC technology, we have identified a population of hepatic CD8+ T cells that are polyfunctional at a single cell level only in a group of vaccinated mice upon malaria challenge. The cytokines/chemokines secreted by these polyfunctional CD8+ T-cell subsets include MIP-1α, RANTES, IFN-γ, and/or IL-17A, which have shown to be associated with protective T-cell responses against certain pathogens. Therefore, a successful induction of such polyfunctional hepatic CD8+ T cells may be a key to the development of effective human malaria vaccine. In addition, the SCBC technology could provide a new level of diagnostic that will allow for a more accurate determination of vaccine efficacy.

Unraveling the role of preexisting immunity in prostate cancer patients vaccinated with a HER-2/neu hybrid peptide

Background

Cancer vaccines aim at eliciting not only an immune response against specific tumor antigens, but also at enhancing a preexisting immunity against the tumor. In this context, we recently reported on the levels of preexisting immunity in prostate cancer patients vaccinated with the HER-2 hybrid peptide (AE37), during a phase I clinical trial. The purpose of the current study was to correlate between preexisting immunity to the native HER-2 peptide, AE36, and expression of HLA-A2 and -A24 molecules with the clinical outcome. Additionally, we investigated the ability of the AE37 vaccine to induce an antitumor immune response against other tumor associated antigens, not integrated in the vaccine formulation, with respect to the clinical response.

Methods

We analyzed prostate cancer patients who were vaccinated with the AE37 vaccine [Ii-Key-HER-2/neu_(776–790) hybrid peptide vaccine (AE37), which is a MHC class II long peptide vaccine encompassing MHC class I epitopes, during a phase I clinical trial. Preexisting immunity to the native HER-2/neu_(776–790) (AE36) peptide was assessed by IFNγ response or dermal reaction at the inoculation site. Antigen specificity against other tumor antigens was defined using multimer analysis. Progression free survival (PFS) was considered as the patients’ clinical outcome. Two-tailed Wilcoxon signed rank test at 95 % confidence interval was used for statistical evaluation at different time points and Kaplan–Meier curves with log-rank (Mantel-Cox) test were used for the evaluation of PFS.

Results

Preexisting immunity to AE36, irrespectively of HLA expression, was correlated with longer PFS. Specific CD8⁺ T cell immunity against E75 and PSA_146–151 (HLA-A2 restricted), as well as, PSA_153–161 (HLA-A24 restricted) was detected at relatively high frequencies which were further enhanced during vaccinations. Specific immunity against PSA_153–161 correlated with longer PFS in HLA-A24⁺ patients. However, HLA-A2⁺ patients with high preexisting or vaccine-induced immunity to E75, showed a trend for shorter PFS.

Conclusions

Our data cast doubt on whether preexisting immunity or epitope spreading specific for HLA-class I-restricted peptides can actually predict a favorable clinical outcome. They also impose that preexisting immunity to long vaccine peptides, encompassing both HLA class II and I epitopes should be considered as an important prerequisite for the improvement of future immunotherapeutic protocols.

Protocol ID Code: Generex-06-07

National Organization for Medicines (EOF) ID Code: IS-107-01-06

NEC Study Code: EED107/1/06

EudraCT Number: 2006-003299-37

Date of registration: 07/06/2006

Date of enrolment of the first participant to the trial: Nov 1st, 2007

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-016-0183-4) contains supplementary material, which is available to authorized users.