Dendritic cell-based vaccines: clinical applications in breast cancer

Modulation of the tumor microenvironment and mechanism of immunotherapy-based drug resistance in breast cancer

Breast cancer, the most frequent female malignancy, is often curable when detected at an early stage. The treatment of metastatic breast cancer is more challenging and may be unresponsive to conventional therapy. Immunotherapy is crucial for treating metastatic breast cancer, but its resistance is a major limitation. The tumor microenvironment (TME) is vital in modulating the immunotherapy response. Various tumor microenvironmental components, such as cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and myeloid-derived suppressor cells (MDSCs), are involved in TME modulation to cause immunotherapy resistance. This review highlights the role of stromal cells in modulating the breast tumor microenvironment, including the involvement of CAF-TAM interaction, alteration of tumor metabolism leading to immunotherapy failure, and other latest strategies, including high throughput genomic screening, single-cell and spatial omics techniques for identifying tumor immune genes regulating immunotherapy response. This review emphasizes the therapeutic approach to overcome breast cancer immune resistance through CAF reprogramming, modulation of TAM polarization, tumor metabolism, and genomic alterations.

Dendritic Cell Subpopulations Are Associated with Prognostic Characteristics of Breast Cancer after Neoadjuvant Chemotherapy-An Observational Study

Breast cancer (BC) is the most prevalent malignancy in women and researchers have strived to develop optimal strategies for its diagnosis and management. Neoadjuvant chemotherapy (NAC), which reduces tumor size, risk of metastasis and patient mortality, often also allows for a de-escalation of breast and axillary surgery. Nonetheless, complete pathological response (pCR) is achieved in no more than 40% of patients who underwent NAC. Dendritic cells (DCs) are professional antigen-presenting cells present in the tumor microenvironment. The multitude of their subtypes was shown to be associated with the pathological and clinical characteristics of BC, but it was not evaluated in BC tissue after NAC. We found that highe r densities of CD123+ plasmacytoid DCs (pDCs) were present in tumors that did not show pCR and had a higher residual cancer burden (RCB) score and class. They were of higher stage and grade and more frequently HER2-negative. The density of CD123+ pCDs was an independent predictor of pCR in the studied group. DC-LAMP+ mature DCs (mDCs) were also related to characteristics of clinical relevance (i.e., pCR, RCB, and nuclear grade), although no clear trends were identified. We conclude that CD123+ pDCs are candidates for a novel biomarker of BC response to NAC.

Breast cancer vaccination: Latest advances with an analytical focus on clinical trials

Breast cancer (BC) is one of the main causes of cancer-related death worldwide. The heterogenicity of breast tumors and the presence of tumor resistance, metastasis, and disease recurrence make BC a challenging malignancy. A new age in cancer treatment is being ushered in by the enormous success of cancer immunotherapy, and therapeutic cancer vaccination is one such area of research. Nevertheless, it has been shown that the application of cancer vaccines in BC as monotherapy could not induce satisfying anti-tumor immunity. Indeed, the application of various vaccine platforms as well as combination therapies like immunotherapy could influence the clinical benefits of BC treatment. We analyzed the clinical trials of BC vaccination and revealed that the majority of trials were in phase I and II meaning that the BC vaccine studies lack favorable outcomes or they need more development. Furthermore, peptide- and cell-based vaccines are the major platforms utilized in clinical trials according to our analysis. Besides, some studies showed satisfying outcomes regarding carbohydrate-based vaccines in BC treatment. Recent advancements in therapeutic vaccines for breast cancer were promising strategies that could be accessible in the near future.

Advancements in dextran-based nanocarriers for treatment and imaging of breast cancer

Breast cancer is the most prevalent type of cancer worldwide,particularly among women, with substantial side effects after therapy. Despite the availability of numerous therapeutic approaches, particularly chemotherapy, the survival rates for breast cancer have declined over time. The therapies currently utilized for breast cancer treatment do not specifically target cancerous cells, resulting in significant adverse effects and potential harm to healthy cells alongside the cancer cells. As a result, nanoparticle-based drug delivery systems have emerged. Among various types of nanoparticles, natural polysaccharide-based nanoparticles have gained significant attention due to their ability to precisely control the drug release and achieve targeted drug delivery. Moreover, polysaccharides are biocompatible, biodegradable, easily modifiable, and renewable, which makes them a unique material for nanoformulation. In recent years, dextran and its derivatives have gained much interest in the field of breast cancer therapy. Dextran is a hydrophilic polysaccharide composed of a main chain formed by α-1,6 linked glucopyranoside residues and a side chain composed of residues linked in α-1,2/3/4 positions. Different dextran-antitumor medication conjugates enhancethe efficacy of anticancer agents. With this context, the present review provides brief insights into dextran and its modification. Further, it meticulously discusses the role of dextran-based nanoparticles in breast cancer therapy and imaging, followed by snippets on their toxicity. Lastly, it presents clinical trials and future perspectives of dextran-based nanoparticles in breast cancer treatment.

The Role of Tumor-Associated Antigen HER2/neu in Tumor Development and the Different Approaches for Using It in Treatment: Many Choices and Future Directions

The treatment of HER2-positive cancers has changed significantly over the past ten years thanks to a significant number of promising new approaches that have been added to our arsenal in the fight against cancer, including monoclonal antibodies, inhibitors of tyrosine kinase, antibody-drug conjugates, vaccination, and particularly, adoptive-T-cell therapy after its great success in hematological malignancies. Equally important is the new methodology for determining patients eligible for targeted HER2 therapy, which has doubled the number of patients who can benefit from these treatments. However, despite the initial enthusiasm, there are still several problems in this field represented by drug resistance and tumor recurrence that require the further development of new more efficient drugs. In this review, we discuss various approaches for targeting the HER2 molecule in cancer treatment, highlighting their benefits and drawbacks, along with the different mechanisms responsible for resistance to HER2-targeted therapies and how to overcome them.

Graphene oxide modulates dendritic cell ability to promote T cell activation and cytokine production

An important aspect of immunotherapy is the ability of dendritic cells (DCs) to prime T cell immunity, an approach that has yielded promising results in some early phase clinical trials. However, novel approaches are required to improve DC therapeutic efficacy by enhancing their uptake of, and activation by, disease relevant antigens. The carbon nano-material graphene oxide (GO) may provide a unique way to deliver antigen to innate immune cells and modify their ability to initiate effective adaptive immune responses. We have assessed whether GO of various lateral sizes affects DC activation and function in vitro and in vivo, including their ability to take up, process and present the well-defined model antigen ovalbumin (OVA). We have found that GO flakes are internalised by DCs, while having minimal effect on their viability, activation phenotype or cytokine production. Although adsorption of OVA protein to either small or large GO flakes promoted its uptake into DCs, large GO interfered with OVA processing. In terms of modulation of DC function, delivery of OVA via small GO flakes significantly enhanced DC ability to induce proliferation of OVA-specific CD4⁺ T cells, promoting granzyme B secretion in vitro. On the other hand, delivery of OVA via large GO flakes augmented DC ability to induce proliferation of OVA-specific CD8⁺ T cells, and their production of IFN-γ and granzyme B. Together, these data demonstrate the capacity of GO of different lateral dimensions to act as a promising delivery platform for DC modulation of distinct facets of the adaptive immune response, information that could be exploited for future development of targeted immunotherapies.

Breast cancer vaccines: New insights into immunomodulatory and nano-therapeutic approaches

Breast cancer (BC) is known to be a highly heterogeneous disease that is clinically subdivided into four primary molecular subtypes, each having distinct morphology and clinical implications. These subtypes are principally defined by hormone receptors and other proteins involved (or not involved) in BC development. BC therapeutic vaccines [including peptide-based vaccines, protein-based vaccines, nucleic acid-based vaccines (DNA/RNA vaccines), bacterial/viral-based vaccines, and different immune cell-based vaccines] have emerged as an appealing class of cancer immunotherapeutics when used alone or combined with other immunotherapies. Employing the immune system to eliminate BC cells is a novel therapeutic modality. The benefit of active immunotherapies is that they develop protection against neoplastic tissue and readjust the immune system to an anti-tumor monitoring state. Such immunovaccines have not yet shown effectiveness for BC treatment in clinical trials. In recent years, nanomedicines have opened new windows to increase the effectiveness of vaccinations to treat BC. In this context, some nanoplatforms have been designed to efficiently deliver molecular, cellular, or subcellular vaccines to BC cells, increasing the efficacy and persistence of anti-tumor immunity while minimizing undesirable side effects. Immunostimulatory nano-adjuvants, liposomal-based vaccines, polymeric vaccines, virus-like particles, lipid/calcium/phosphate nanoparticles, chitosan-derived nanostructures, porous silicon microparticles, and selenium nanoparticles are among the newly designed nanostructures that have been used to facilitate antigen internalization and presentation by antigen-presenting cells, increase antigen stability, enhance vaccine antigenicity and remedial effectivity, promote antigen escape from the endosome, improve cytotoxic T lymphocyte responses, and produce humoral immune responses in BC cells. Here, we summarized the existing subtypes of BC and shed light on immunomodulatory and nano-therapeutic strategies for BC vaccination. Finally, we reviewed ongoing clinical trials on BC vaccination and highlighted near-term opportunities for moving forward.

Recent Progress on Therapeutic Vaccines for Breast Cancer

Breast cancer remains the most frequently diagnosed malignancy worldwide. Advanced breast cancer is still an incurable disease mainly because of its heterogeneity and limited immunogenicity. The great success of cancer immunotherapy is paving the way for a new era in cancer treatment, and therapeutic cancer vaccination is an area of interest. Vaccine targets include tumor-associated antigens and tumor-specific antigens. Immune responses differ in different vaccine delivery platforms. Next-generation sequencing technologies and computational analysis have recently made personalized vaccination possible. However, only a few cases benefiting from neoantigen-based treatment have been reported in breast cancer, and more attention has been given to overexpressed antigen-based treatment, especially human epidermal growth factor 2-derived peptide vaccines. Here, we discuss recent advancements in therapeutic vaccines for breast cancer and highlight near-term opportunities for moving forward.

Therapeutic vaccines for breast cancer: Has the time finally come?

The ability to exploit the immune system as a weapon against cancer has revolutionised the treatment of cancer patients, especially through immune checkpoint inhibitors (ICIs). However, ICIs demonstrated a modest benefit in treating breast cancer (BC), with the exception of certain subsets of triple-negative BCs. An immune-suppressive tumour microenvironment (TME), typically present in BC, is an important factor in the poor response to immunotherapy. After almost two decades of poor clinical trial results, cancer vaccines (CVs), an active immunotherapy, have come back in the spotlight because of some technological advancements, ultimately boosted by coronavirus disease 2019 pandemic. In particular, neoantigens are emerging as the preferred targets for CVs, with gene-based and viral vector-based platforms in development. Moreover, lipid nanoparticles proved to be immunogenic and efficient delivery vehicles. Past clinical trials investigating CVs focused especially on the metastatic disease, where the TME is more likely compromised by inhibitory mechanisms. In this sense, favouring the use of CVs as monotherapy in premalignant or in the adjuvant setting and establishing combination treatments (i.e. CV plus ICI) in late-stage disease are promising strategies. This review provides a full overview of the past and current breast cancer vaccine landscape.

Current understandings and clinical translation of nanomedicines for breast cancer therapy

Breast cancer is one of the most frequently diagnosed cancers that is threatening women's life. Current clinical treatment regimens for breast cancer often involve neoadjuvant and adjuvant systemic therapies, which somewhat are associated with unfavorable features. Also, the heterogeneous nature of breast cancers requires precision medicine that cannot be fulfilled by a single type of systemically administered drug. Taking advantage of the nanocarriers, nanomedicines emerge as promising therapeutic agents for breast cancer that could resolve the defects of drugs and achieve precise drug delivery to almost all sites of primary and metastatic breast tumors (e.g. tumor vasculature, tumor stroma components, breast cancer cells, and some immune cells). Seven nanomedicines as represented by Doxil® have been approved for breast cancer clinical treatment so far. More nanomedicines including both non-targeting and active targeting nanomedicines are being evaluated in the clinical trials. However, we have to realize that the translation of nanomedicines, particularly the active targeting nanomedicines is not as successful as people have expected. This review provides a comprehensive landscape of the nanomedicines for breast cancer treatment, from laboratory investigations to clinical applications. We also highlight the key advances in the understanding of the biological fate and the targeting strategies of breast cancer nanomedicine and the implications to clinical translation.

Advancements in Human Breast Cancer Targeted Therapy and Immunotherapy

Human breast cancer treatment regimens have evolved greatly due to the significant advances in understanding the molecular mechanisms and pathways of the common subtypes of breast cancer. In this review, we discuss recent progress in breast cancer targeted therapy and immunotherapy as well as ongoing clinical trials. We also highlight the potential of combination therapies and personalized approaches to improve clinical outcomes. Targeted therapies have surpassed the hormone receptors and the human epidermal growth factor receptor 2 (HER2) to include many other molecules in targetable pathways such as the epidermal growth factor receptor (EGFR), poly (adenosine diphosphate-ribose) polymerase (PARP), and cyclin-dependent kinase 4/6 (CDK4/6). However, resistance to targeted therapy persists, underpinning the need for more efficacious therapies. Immunotherapy is considered a milestone in breast cancer treatments, including the engineered immune cells (CAR-T cell therapy) to better target the tumor cells, vaccines to stimulate the patient's immune system against tumor antigens, and checkpoint inhibitors (PD-1, PD-L1, and CTLA4) to block molecules that mediate immune inhibition. Targeted therapies and immunotherapy tested in breast cancer clinical trials are discussed here, with special emphasis on combinatorial approaches which are believed to maximize treatment efficacy and enhance patient survival.

Application of immunotherapy based on dendritic cells stimulated by tumor cell-derived exosomes in a syngeneic breast tumor mouse model

We here evaluated the therapeutic effect of tumor cell-derived exosomes (TEXs)-stimulated dendritic cells (DCs) in a syngeneic orthotopic breast tumor model. The DC line DC2.4 and breast cancer cell line E0771 originally isolated from C57BL/6 mice were used. E0771 cells stably expressing the exosomal CD63-RFP or luciferase (Luc) and DC2.4 cells stably expressing GFP were produced using lentivirus. TEXs were purified from conditioned medium of E0771/CD63-RFP cells. Breast tumor model was established by injecting E0771/Luc cells into mammary gland fat pad of mice. TEXs contained immune modulatory molecules such as HSP70, HSP90, MHC I, MHC II, TGF-β, and PD-L1. TEXs were easily taken by DC2.4 cells, resulting in a significant increase in the in vitro proliferation and migration abilities of DC2.4 cells, accompanied by the upregulation of CD40. TEX-DC-treated group exhibited a decreased tumor growth compared with control group. CD8⁺ cells were more abundant in the tumors and lymph nodes of TEX-DC-treated group than in those of control group, whereas many CD4⁺ or FOXP3+ cells were localized in those of control group. Our results suggest a potential application of TEX-DC-based cancer immunotherapy.

•

TEXs contained immune modulatory molecules such as HSP70, HSP90, MHC I, MHC II, TGF-β, and PD-L1. .

•

TEXs increased the proliferation and migration capacities of dendritic cells.

•

TEXs up regulated CD40 molecule on dendritic cells.

•

TEX-stimulated dendritic cells suppressed tumor growth, with accompanying increase in CD8⁺ T cell infiltration.

Inflammation and tumor progression: signaling pathways and targeted intervention

Cancer development and its response to therapy are regulated by inflammation, which either promotes or suppresses tumor progression, potentially displaying opposing effects on therapeutic outcomes. Chronic inflammation facilitates tumor progression and treatment resistance, whereas induction of acute inflammatory reactions often stimulates the maturation of dendritic cells (DCs) and antigen presentation, leading to anti-tumor immune responses. In addition, multiple signaling pathways, such as nuclear factor kappa B (NF-kB), Janus kinase/signal transducers and activators of transcription (JAK-STAT), toll-like receptor (TLR) pathways, cGAS/STING, and mitogen-activated protein kinase (MAPK); inflammatory factors, including cytokines (e.g., interleukin (IL), interferon (IFN), and tumor necrosis factor (TNF)-α), chemokines (e.g., C-C motif chemokine ligands (CCLs) and C-X-C motif chemokine ligands (CXCLs)), growth factors (e.g., vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β), and inflammasome; as well as inflammatory metabolites including prostaglandins, leukotrienes, thromboxane, and specialized proresolving mediators (SPM), have been identified as pivotal regulators of the initiation and resolution of inflammation. Nowadays, local irradiation, recombinant cytokines, neutralizing antibodies, small-molecule inhibitors, DC vaccines, oncolytic viruses, TLR agonists, and SPM have been developed to specifically modulate inflammation in cancer therapy, with some of these factors already undergoing clinical trials. Herein, we discuss the initiation and resolution of inflammation, the crosstalk between tumor development and inflammatory processes. We also highlight potential targets for harnessing inflammation in the treatment of cancer.

Dendritic Cells Are Associated with Prognosis and Survival in Breast Cancer

Dendritic cells (DCs) constitute a part of the tumour microenvironment, but we are still far from understanding their complex role in immune response to the tumour. This study aimed to investigate the density of DCs expressing CD1a, CD83, CD123, DC-LAMP3 (CD208) and DC-SIGN (CD209) in breast cancer. The correlations between DC density and molecular subtype of breast cancer, its hormone receptor status, spatial location and their associations with clinical and pathological prognostic factors were evaluated. We have shown that intratumoural CD1a+ cells were significantly associated with progression-free survival. For LAMP3+ and CD123+ DCs, higher cell densities were associated with non-luminal as compared to luminal cancer phenotype. In contrast, dense CD83+ DC infiltrate was observed in luminal tumours. The number of CD1a+ DCs in both locations was the highest in luminal B/HER2+ cancers. The highest positive cell count of LAMP3+ cells was observed in the triple-negative subtype in both locations. We found higher numbers of LAMP3+ DCs both intratumourally and at the invasive margin, as well as CD123+ DCs intratumourally in tumours with negative expression of oestrogen or progesterone receptors. Our study demonstrates associations between DC subpopulations and histological and clinical characteristics, as well as molecular subtypes in breast carcinoma.

Cancer Vaccines, Treatment of the Future: With Emphasis on HER2-Positive Breast Cancer

Breast cancer is one of the leading causes of death in women. With improvements in early-stage diagnosis and targeted therapies, there has been an improvement in the overall survival rate in breast cancer over the past decade. Despite the development of targeted therapies, tyrosine kinase inhibitors, as well as monoclonal antibodies and their toxin conjugates, all metastatic tumors develop resistance, and nearly one-third of HER2+ breast cancer patients develop resistance to all these therapies. Although antibody therapy has shown promising results in breast cancer patients, passive immunotherapy approaches have limitations and need continuous administration over a long period. Vaccine therapy introduces antigens that act on cancer cells causing prolonged activation of the immune system. In particular, cancer relapse could be avoided due to the presence of a longer period of immunological memory with an effective vaccine that can protect against various tumor antigens. Cancer vaccines are broadly classified as preventive and therapeutic. Preventive vaccines are used to ward off any future infections and therapeutic vaccines are used to treat a person with active disease. In this article, we provided details about the tumor environment, different types of vaccines, their advantages and disadvantages, and the current status of various vaccine candidates with a focus on vaccines for breast cancer. Current data indicate that therapeutic vaccines themselves have limitations in terms of efficacy and are used in combination with other chemotherapeutic or targeting agents. The majority of breast cancer vaccines are undergoing clinical trials and the next decade will see the fruitfulness of breast cancer vaccine therapy.

Noninvasive Photoacoustic Imaging of Dendritic Cell Stimulated with Tumor Cell-Derived Exosome

PURPOSE

The tools to trigger dendritic cell (DC) activation and to verify DC migration in vivo are important for directing DC immunotherapy toward successful treatment. We evaluated whether tumor cell-derived exosome (TEX)-stimulated DC migration into lymph node (LN) in mouse could be tracked using gold nanoparticle (GN)-labeling and ultrasound (US)-guided photoacoustic imaging (PAI).

PROCEDURES

GFP-transduced DC2.4 cells were used. RFP-tagged TEXs were purified from a stable 4T1 cell line overexpressing the exosomal CD63-RFP fusion protein. The TEX uptake by DCs was visualized using confocal laser scanning microscopy. GNs with surface plasmon resonance at 808 nm were used for DC-labeling. DCs that migrated into axillary LN were longitudinally monitored by US-guided PAI and analyzed by silver staining and immunohistochemistry.

RESULTS

TEXs were easily internalized in DCs, increased proliferation and migration capacities, and upregulated co-stimulatory molecules, CCR7 and TNF-α without cytotoxicity. The GN-labeling exerted no adverse effects on the biological functions of DCs. US-guided PAI and DC-labeling allowed for sensitive and longitudinal monitoring of TEX-stimulated DC migration toaxillary LN.

CONCLUSIONS

TEXs efficiently activated DCs and GN-labeled DC migration into LN was successfully monitored using US-guided PAI, suggesting that TEXs are a good source for DC activation and US-guided PAI is a cost-effective and easy-to-use imaging modality for noninvasive tracking of DCs.

Label-Free, High-Throughput Assay of Human Dendritic Cells from Whole-Blood Samples with Microfluidic Inertial Separation Suitable for Resource-Limited Manufacturing

Microfluidics technology has not impacted the delivery and accessibility of point-of-care health services, like diagnosing infectious disease, monitoring health or delivering interventions. Most microfluidics prototypes in academic research are not easy to scale-up with industrial-scale fabrication techniques and cannot be operated without complex manipulations of supporting equipment and additives, such as labels or reagents. We propose a label- and reagent-free inertial spiral microfluidic device to separate red blood, white blood and dendritic cells from blood fluid, for applications in health monitoring and immunotherapy. We demonstrate that using larger channel widths, in the range of 200 to 600 µm, allows separation of cells into multiple focused streams, according to different size ranges, and we utilize a novel technique to collect the closely separated focused cell streams, without constricting the channel. Our contribution is a method to adapt spiral inertial microfluidic designs to separate more than two cell types in the same device, which is robust against clogging, simple to operate and suitable for fabrication and deployment in resource-limited populations. When tested on actual human blood cells, 77% of dendritic cells were separated and 80% of cells remained viable after our assay.

Breast cancer stem cell RNA-pulsed dendritic cells enhance tumor cell killing by effector T cells

Cancer stem cells (CSCs) underpin the resistance of breast cancer (BC) cells to therapy. Dendritic cell (DC)-based treatment is efficacious and safe, but the efficiency of this technique for targeting CSCs in BC treatment requires further investigation. The present study aimed to investigate the ability of DCs pulsed with breast CSC antigens to activate effector lymphocytes for killing BC cells. CD44⁺/CD24⁻ CSCs were isolated from BCA55-121, an in-house patient-derived BC cell line, and acquisition of stemness properties was confirmed by upregulated expression of OCT4A and a superior proliferative capacity in colony formation assays compared with whole population of BCA55-121 (BCA55-121-WP). DCs were differentiated from monocytes from peripheral blood of healthy donors and pulsed with CSC total RNA. Maturation of the CSC RNA-pulsed DCs was confirmed by increased expression of CD11c, CD40, CD83, CD86 and HLA-DR, as well as reduced CD14 expression compared with monocytes. Total lymphocytes co-cultured with CSC RNA-pulsed DCs were analyzed by flow cytometry for markers including CD3, CD4, CD8, CD16 and CD56. The results revealed that the co-cultures contained mostly cytotoxic CD8+ T lymphocytes followed by CD4+ T lymphocytes and smaller populations of natural killer (NK) and NKT cells. ELISA was used to measure IFN-γ production, and it was revealed that activated CD4⁺ and CD8+ lymphocytes produced more IFN-γ compared with naïve T cells, suggesting that CD8+ T cells were effector T cells. CSC RNA was a more efficient antigen source compared with RNA from mixed BC cells for activating tumor antigen-specific killing by T cells. These CSC-specific effector T cells significantly induced BC cell apoptosis at a 20:1 effector T cell:tumor cell ratio. Of note, the breast CSCs cultures demonstrated resistance to effector T cell killing, which was in part due to increased expression of programmed death ligand 1 in the CSC population. The present study highlights the potential use of CSC RNA for priming DCs in modulating an anticancer immune response against BC.

HER2-Positive Breast Cancer Immunotherapy: A Focus on Vaccine Development

Clinical progress in the field of HER2-positive breast cancer therapy has been dramatically improved by understanding of the immune regulatory mechanisms of tumor microenvironment. Passive immunotherapy utilizing recombinant monoclonal antibodies (mAbs), particularly trastuzumab and pertuzumab has proved to be an effective strategy in HER2-positive breast cancer treatment. However, resistance to mAb therapy and relapse of disease are still considered important challenges in clinical practice. There are increasing reports on the induction of cellular and humoral immune responses in HER2-positive breast cancer patients. More recently, increasing efforts are focused on using HER2-derived peptide vaccines for active immunotherapy. Here, we discuss the development of various HER2-derived vaccines tested in animal models and human clinical trials. Different formulations and strategies to improve immunogenicity of the antigens in animal studies are also discussed. Furthermore, other immunotherapeutic approaches to HER2 breast cancer including, CTLA-4 inhibitors, immune checkpoint inhibitors, anti PD-1/PD-L1 antibodies are presented.

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

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

Eradication of HCV Infection with the Direct-Acting Antiviral Therapy in Renal Allograft Recipients

Hepatitis C virus (HCV) infection unfavorably affects the survival of both renal patients undergoing hemodialysis and renal transplant recipients. In this subset of patients, the effectiveness and safety of different combinations of interferon-free direct-acting antiviral agents (DAAs) have been analyzed in several small studies. Despite fragmentary, the available data demonstrate that DAA treatment is safe and effective in eradicating HCV infection, with a sustained virologic response (SVR) rates nearly 95% and without an increased risk of allograft rejection. This review article analyzes the results of most published studies on this topic to favor more in-depth knowledge of the readers on the subject. We suggest, however, perseverating in this update as the optimal DAA regimen may not be proposed yet, because of the expected arrival of newer DAAs and of the lack of data from large multicenter randomized controlled trials.

Investigation of parameters that determine Nano-DC vaccine transport

Effective migration of dendritic cells into the lymphatic system organs is the prerequisite for a functional dendritic cell vaccine. We have previously developed a porous silicon microparticle (PSM)-based therapeutic dendritic cell vaccine (Nano-DC vaccine) where PSM serves both as the vehicle for antigen peptides and an adjuvant. Here, we analyzed parameters that determined dendritic cell uptake of PSM particles and Nano-DC vaccine accumulation in lymphatic tissues in a murine model of HER2-positive breast cancer. Our study revealed a positive correlation between sphericity of the PSM particles and their cellular uptake by circulating dendritic cells. In addition, the intravenously administered vaccines accumulated more in the spleens and inguinal lymph nodes, while the intradermally inoculated vaccines got enriched in the popliteal lymph nodes. Furthermore, mice with large tumors received more vaccines in the lymph nodes than those with small to medium size tumors. Information from this study will provide guidance on design and optimization of future therapeutic cancer vaccines.

CRISPR Technology for Breast Cancer: Diagnostics, Modeling, and Therapy

Molecularly, breast cancer represents a highly heterogenous family of neoplastic disorders, with substantial interpatient variations regarding genetic mutations, cell composition, transcriptional profiles, and treatment response. Consequently, there is an increasing demand for alternative diagnostic approaches aimed at the molecular annotation of the disease on a patient-by-patient basis and the design of more personalized treatments. The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) technology enables the development of such novel approaches. For instance, in diagnostics, the use of the RNA-specific C2c2 system allows ultrasensitive nucleic acid detection and could be used to characterize the mutational repertoire and transcriptional breast cancer signatures. In disease modeling, CRISPR/Cas9 technology can be applied to selectively engineer oncogenes and tumor-suppressor genes involved in disease pathogenesis. In treatment, CRISPR/Cas9 can be used to develop gene-therapy, while its catalytically-dead variant (dCas9) can be applied to reprogram the epigenetic landscape of malignant cells. As immunotherapy becomes increasingly prominent in cancer treatment, CRISPR/Cas9 can engineer the immune cells to redirect them against cancer cells and potentiate antitumor immune responses. In this review, CRISPR strategies for the advancement of breast cancer diagnostics, modeling, and treatment are highlighted, culminating in a perspective on developing a precision medicine-based approach against breast cancer.

Current Approaches in Development of Immunotherapeutic Vaccines for Breast Cancer

Cancer is the leading cause of death worldwide. In developed as well as developing countries, breast cancer is the most common cancer found among women. Currently, treatment of breast cancer consists mainly of surgery, chemotherapy, hormone therapy, and radiotherapy. In recent years, because of increased understanding of the therapeutic potential of immunotherapy in cancer prevention, cancer vaccines have gained importance. Here, we review various immunotherapeutic breast cancer vaccines including peptide-based vaccines, whole tumor cell vaccines, gene-based vaccines, and dendritic cell vaccines. We also discuss novel nanotechnology-based approaches to improving breast cancer vaccine efficiency.

Exosomes derived from rAAV/AFP-transfected dendritic cells elicit specific T cell-mediated immune responses against hepatocellular carcinoma

Background

Dendritic cell (DC)-derived exosomes (Dexs) have been proved to induce and enhance antigen-specific T cell responses in vivo, and previous clinical trials have shown the feasibility and safety of Dexs in multiple human cancers. However, there is little knowledge on the efficacy of Dexs against hepatocellular carcinoma (HCC) until now.

Methods

In this study, human peripheral blood-derived DCs were loaded with recombinant adeno-associated viral vector (rAAV)-carrying alpha-fetoprotein (AFP) gene (rAAV/AFP), and high-purity Dexs were generated. Then naive T cells were stimulated with Dexs to investigate the specific T cell-mediated immune responses against HCC.

Results

Our findings showed that Dexs were effective to stimulate naive T cell proliferation and induce T cell activation to become antigen-specific cytotoxic T lymphocytes (CTLs), thereby exhibiting antitumor immune responses against HCC. In addition, Dex-sensitized DC precursors seemed more effective to trigger major histocompatibility complex class I (MHC I)-restricted CTL response and allow DCs to make full use of the minor antigen peptides, thereby maximally activating specific immune responses against HCC.

Conclusion

It is concluded that Dexs, which combine the advantages of DCs and cell-free vectors, are promising to completely, or at least in part, replace mature DCs (mDCs) to function as cancer vaccines or natural antitumor adjuvant.

Antigen-loaded dendritic cells triggers a specific cytotoxic T lymphocytes immune response against hepatocellular carcinoma: in vitro study

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the common malignancies, characterized by poor response to conventional therapeutic options. Immunotherapy with dendritic cells (DCs)-vaccines is one of the most successful strategies used for the treatment of HCC. However, the methods applied in the preparation of antigen-loaded DCs are important factors for optimization of DCs vaccines.

PURPOSE

The present study was conducted to investigate the effect of HCC-whole tumor cell lysate prepared using rapid repetitive freeze-thaw cycles on the immunogenicity of DCs and evaluate the ability of whole tumor cell lysate-pulsed DCs vaccine to induce a specific cytotoxic T lymphocytes (CTLs) response against HepG2 cell line.

METHODS

Immature DCs generated from peripheral blood monocytes were randomized into two groups: control DCs and whole tumor cell lysate-pulsed DCs. Phenotypic analysis of the DCs' cell maturation marker CD83 and co-stimulatory molecule CD86 was performed. HCC-specific cytotoxic activity of CD8⁺ CTLs was measured in vitro.

RESULTS

Loading of DCs with necrotic whole cell lysate resulted in non-significant changes in DCs' expression of CD83, but a significant increase in expression of CD86. In addition, CD8⁺ CTLs stimulated with whole tumor cell lysate-pulsed DCs showed a high cytotoxic activity that specifically attack HepG2 cells.

CONCLUSION

Our findings indicated that pulsation of DCs with whole tumor cell lysate prepared by repetitive freeze-thaw cycles could efficiently enhance the ability of DCs to induce proliferation and clonal expansion of CD8⁺ CTLs. Data herein, also indicated that whole tumor cell lysate-pulsed DCs triggers a specific CD8⁺ CTLs against HCC tumor cells.

Triple negative breast cancer - prognostic role of immune-related factors: a systematic review

PURPOSE

Treatment of breast cancer has been increasingly successful in recent years with the advent of HER2-receptor targeted treatment and endocrine treatment. However, the triple negative subgroup of breast cancer (TNBC) (estrogen-, progesterone- and HER2-receptor negative) still lacks targeted treatment options. TNBC is a type of breast cancer that often affects younger women, and generally has a worse prognosis than other types of breast cancer. Recently, the complex role of the immune system in cancer growth, elimination and metastasis has been the object of increased attention. There is hope that a more detailed understanding of the intricate roles of the constituents of the immune system, will hold potential both as prognostic or predictive markers of cancer progression, but also as treatment targets for a wide range of tumors, including TNBC. The aim of this review is to provide an overview of the cellular immune microenvironment in TNBC, and to highlight areas in which TNBC may differ from other types of breast cancer.

MATERIAL AND METHODS

A search of PubMed was made using the terms 'triple negative breast cancer' and 'tumor infiltrating lymphocytes', 'CD8', 'CD4', 'B cells', 'natural killer cells', 'macrophages', myeloid derived suppressor cells', 'dendritic cells', 'immune check point inhibitor', 'CTLA-4' and 'PD-L1'.

RESULTS

We find that whilst factors such as TILs and certain subgroups of TILs (e.g., CD8 + and regulator T-cells) have been extensively researched, none of these markers are currently applicable to routine clinical practice. Also, TNBC differs from other types of breast cancer with regards to cellular composition of the immune infiltrate and PD-L1 expression, and the prognostic significance of these.

CONCLUSIONS

Immune-related factors have the potential as both prognostic and predictive biomarkers for new treatments targeting the immune system in breast cancer. However, multivariate analyses, taking other well-known factors into account, are required to determine the true value of these biomarkers. Also, differences between TNBC and other types of breast cancer may have implications for treatment and use of immune-related factors as biomarkers.

Use of antigen-primed dendritic cells for inducing antitumor immune responses in vitro in patients with non-small cell lung cancer

Cancer is associated with a reduction in immature and mature circulating dendritic cells (DCs), and with an impaired migratory capacity, compared with healthy donors. Therefore, modern approaches to the in vitro generation of DCs loaded with tumor antigens and their use for inducing antitumor immune responses in vivo are being investigated. The purpose of the present study was to investigate the phenotypic and functional characteristics of peripheral blood DC subsets in patients with non-small cell lung cancer (NSCLC), and the development of an antitumor cytotoxic response by mononuclear cells (MNCs) from patients using in vitro generated antigen-primed DCs. Heparinized peripheral venous blood samples were obtained from 10 healthy donors and 20 patients with a histologically verified diagnosis of NSCLC. The ability of antigen-activated DCs to stimulate the activity of MNCs against autologous tumor cells was evaluated using a cytotoxic test. Peripheral blood DC subsets from patients with NSCLC were identified to be decreased and to exhibit an impaired ability to mature, compared with healthy donors. Furthermore, DCs generated from MNCs from patients with NSCLC were able to stimulate a specific cytotoxic response when loaded with autologous tumor lysates or RNA and matured, in vitro. A perforin and granzyme B-dependent mode of cytotoxicity was primarily induced. The ability of DCs loaded with tumor antigens to increase the cytotoxic activity of MNCs against NSCLC cells in vitro indicates the effective induction and co-stimulation of T lymphocytes by the generated DCs.

CTLA-4 positive breast cancer cells suppress dendritic cells maturation and function

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), a potent immunoregulatory molecule, can down-regulate T-cell activation and inhibit anti-tumor immune response. This study showed that LPS-stimulated human dendritic cells (DCs) decreased the expression of HLA-DR, CD83 and costimulatory molecules (CD40, CD80 and CD86) following coculturing with CTLA-4⁺ breast cancer cells. Moreover, the suppressed DCs further inhibited proliferation of allogeneic CD4⁺/CD8⁺ T-cells, differentiation of Th1 and function of cytotoxic lymphocytes (CTLs). However, CTLA-4 blockade in breast cancer cells could recover DC maturation and cytokine production, elevate antigen-presenting function of DCs, reverse Th1/CTLs response and cytokine secretion. Subsequent study demonstrated that the activation of extracellular-signal regulated kinase and signal transducer and activator of transcription 3 of DCs caused by CTLA-4⁺ breast cancer cells were the predominant mechanism of DC suppression. In addition, CTLA-4 blockade treatment also directly inhibited proliferation and induced apoptosis of CTLA-4⁺ breast cancer cells. Collectively, CTLA-4 was expressed and functional on human breast cancer cells through influencing maturation and function of DCs in vitro, and CTLA-4 blockage not only recovered the antigen-presenting function of DCs and T-cells activation but also suppressed the biological activity of breast cancer cells themselves. This study highlights the clinical application of CTLA-4 blockade therapy in breast cancer.

Generation of populations of antigen-specific cytotoxic T cells using DCs transfected with DNA construct encoding HER2/neu tumor antigen epitopes

BACKGROUND

Recent fundamental and clinical studies have confirmed the effectiveness of utilizing the potential of the immune system to remove tumor cells disseminated in a patient's body. Cytotoxic T lymphocytes (CTLs) are considered the main effectors in cell-mediated antitumor immunity. Approaches based on antigen presentation to CTLs by dendritic cells (DCs) are currently being intensively studied, because DCs are more efficient in tumor antigen presentation to T cells through their initiation of strong specific antitumor immune responses than other types of antigen-presenting cells. Today, it has become possible to isolate CTLs specific for certain antigenic determinants from heterogeneous populations of mononuclear cells. This enables direct and specific cell-mediated immune responses against cells carrying certain antigens. The aim of the present study was to develop an optimized protocol for generating CTL populations specific for epitopes of tumor-associated antigen HER2/neu, and to assess their cytotoxic effects against the HER2/neu-expressing MCF-7 tumor cell line.

METHODS

The developed protocol included sequential stages of obtaining mature DCs from PBMCs from HLA A*02-positive healthy donors, magnet-assisted transfection of mature DCs with the pMax plasmid encoding immunogenic peptides HER2 p369-377 (E75 peptide) and HER2 p689-697 (E88 peptide), coculture of antigen-activated DCs with autologous lymphocytes, magnetic-activated sorting of CTLs specific to HER2 epitopes, and stimulation of isolated CTLs with cytokines (IL-2, IL-7, and IL-15).

RESULTS

The resulting CTL populations were characterized by high contents of CD8⁺ cells (71.5% in cultures of E88-specific T cells and 90.2% in cultures of E75-specific T cells) and displayed strong cytotoxic effects against the MCF-7 cell line (percentages of damaged tumor cells in samples under investigation were 60.2 and 65.7% for E88- and E75-specific T cells, respectively; level of spontaneous death of target cells was 17.9%).

CONCLUSIONS

The developed protocol improves the efficiency of obtaining HER2/neu-specific CTLs and can be further used to obtain cell-based vaccines for eradicating targeted tumor cells to prevent tumor recurrence after the major tumor burden has been eliminated and preventing metastasis in patients with HER2-overexpressing tumors.

Mechanism of immune evasion in breast cancer

Breast cancer (BC) is the most common malignant tumor among women, with high morbidity and mortality. Its onset, development, metastasis, and prognosis vary among individuals due to the interactions between tumors and host immunity. Many diverse mechanisms have been associated with BC, with immune evasion being the most widely studied to date. Tumor cells can escape from the body’s immune response, which targets abnormal components and foreign bodies, using different approaches including modification of surface antigens and modulation of the surrounding environment. In this review, we summarize the mechanisms and factors that impact the immunoediting process and analyze their functions in detail.

Toll-like receptor 3-induced immune response by poly(d,l-lactide-co-glycolide) nanoparticles for dendritic cell-based cancer immunotherapy

Dendritic cells (DCs) are potent professional antigen-presenting cells that are capable of initiating a primary immune response and activating T cells, and they play a pivotal role in the immune responses of the host to cancer. Prior to antigen presentation, efficient antigen and adjuvant uptake by DCs is necessary to induce their maturation and cytokine generation. Nanoparticles (NPs) are capable of intracellular delivery of both antigen and adjuvant to DCs. Here, we developed an advanced poly(d,l-lactide-co-glycolide) (PLGA)-NP encapsulating both ovalbumin (OVA) as a model antigen and polyinosinic-polycytidylic acid sodium salt (Toll-like receptor 3 ligand) as an adjuvant to increase intracellular delivery and promote DC maturation. The PLGA-NPs were taken up by DCs, and their uptake greatly facilitated major histocompatibility class I antigen presentation in vitro. Moreover, vaccination with PLGA-NP-treated DCs led to the generation of ovalbumin-specific CD8⁺ T cells, and the resulting antitumor efficacy was significantly increased in EG.7 and TC-1 tumor-bearing mice compared to control mice (P<0.01). Taken together, these findings demonstrated that the PLGA-NP platform may be an effective method for delivering tumor-specific antigens or adjuvants to DCs.

In vitro inhibitory effects of thymol and carvacrol on dendritic cell activation and function

CONTEXT

Thyme has been used in traditional medicine for medicinal purposes since ancient times.

OBJECTIVE

The objective of this study was to investigate the effects of thymol and carvacrol as two major constituents of thyme on dendritic cells (DCs) maturation and T cell activation.

MATERIALS AND METHODS

Splenic DCs were treated with non-cytotoxic concentrations of the components and then analyzed for MHC II, CD86, and CD40 expression by flow cytometry. The effects of compounds on mitogenic, as well as allogenic T cell responses in mixed lymphocyte culture (MLR) and the release of cytokines were investigated.

RESULTS

At 0.1 µg/ml, reduced mean fluorescent intensity (MFI) of CD86 for thymol (80.3 ± 0.2% of untreated control) and CD40 for carvacrol (79.5 ± 0.14%) was observed (p < 0.001). Decreased mitogenic T cell proliferation by thymol [proliferation index (PI) from 0.93 ± 0.11 at 1 µg/ml to 0.42 ± 0.16 at 100 µg/ml (p < 0.01)] and carvacrol [PI from 1.08 ± 0.3 at 1 µg/ml to 0.28 ± 0.1 at 100 µg/ml (p < 0.001)] was seen. Ten micrograms/ml thymol (PI, 0.85 ± 0.04) and carvacrol (PI, 0.89 ± 0.03) inhibited allogenic T cell response (p < 0.05). Decreased IFN-γ level in MLR supernatant from 1441 ± 27.7 pg/ml in untreated cells to 944 ± 32.1 at 10 µg/ml of thymol and of carvacrol (886 ± 31.7 pg/ml) (p < 0.01) was found. IL-4 levels were decreased in the presence of both compounds (p < 0.01).

CONCLUSION

These data showed the suppressive effects of thymol and carvacrol on DCs maturation and function, as well as T cell responses.

Long-term survival of a breast cancer patient with extensive liver metastases upon immune and virotherapy: a case report

Liver metastases in breast cancer are associated with a poor prognosis. We report long-term survival of a patient with breast cancer and liver metastases. After operation the patient declined further standard therapy. Instead, she was treated with local hyperthermia, Newcastle disease virus and dendritic cell vaccination at the Immunological and Oncological Center Cologne (IOZK), Germany. A continuous high quality of life was reported and the patient survived more than 66 months after initial diagnosis. No recurrence or further metastases developed under treatment. Following treatment, a long-lasting tumor-reactive memory T-cell responsiveness could be documented. This possibly explains the favorable course of disease. Since this combination of therapies is not restricted to a particular tumor type, further exploration is warranted.