Harnessing the immune system in the battle against breast cancer

Emerging treatments in HER2-positive advanced breast cancer: Keep raising the bar

Patients with human epidermal receptor 2 (HER2)-positive breast cancer are experiencing a consistent shift toward better survival across the years, thanks to tremendous advancements in treatment strategies. The consistent improvements of outcomes set a high bar for new drug development and the need to explore new ways to overcome resistance mechanisms. Emerging treatments in HER2-positive breast cancer aim to tackle the disease by acting on different targets, including not only HER2 (both at the extra- and intracellular level), but also HER3, PD-(L)1, CTLA4, NKG2A, AKT, PI3K, and, in triple-positive tumors, the estrogen receptors and the cyclin-dependent kinases 4/6. This review describes the evolving treatment landscape of HER2-positive breast cancer, from the current approved therapies to the future perspectives, with a focus on the new agents which are likely to get approved in the next future.

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.

Knowledge mapping of therapeutic cancer vaccine from 2013 to 2022: A bibliometric and visual analysis

The investigation of therapeutic cancer vaccines has been ongoing for the past century. Herein, we used VOSviewer and CiteSpace to perform the first global bibliometric analysis of the literature on therapeutic cancer vaccines from 2013 to 2022 aiming to explore the current status and potential research trends. The findings revealed a consistent upward trend in both publication counts and citations. The United States emerged as the leading contributor with the highest number of published papers. Additionally, the analysis of references and keywords indicated that therapeutic cancer vaccines have long been popular topics, whereas neoantigen vaccines, mRNA vaccines, combination strategies, and vaccine delivery systems are emerging research hotspots. This bibliometric study provides a comprehensive and important overview of the current knowledge and potential developments in therapeutic cancer vaccines from 2013 to 2022, which may serve as a valuable reference for scholars interested in further exploring this promising field.

Insight into the Crosstalk between Photodynamic Therapy and Immunotherapy in Breast Cancer

Breast cancer (BC) is the world's second most frequent malignancy and the leading cause of mortality among women. All in situ or invasive breast cancer derives from terminal tubulobular units; when the tumor is present only in the ducts or lobules in situ, it is called ductal carcinoma in situ (DCIS)/lobular carcinoma in situ (LCIS). The biggest risk factors are age, mutations in breast cancer genes 1 or 2 (BRCA1 or BRCA2), and dense breast tissue. Current treatments are associated with various side effects, recurrence, and poor quality of life. The critical role of the immune system in breast cancer progression/regression should always be considered. Several immunotherapy techniques for BC have been studied, including tumor-targeted antibodies (bispecific antibodies), adoptive T cell therapy, vaccinations, and immune checkpoint inhibition with anti-PD-1 antibodies. In the last decade, significant breakthroughs have been made in breast cancer immunotherapy. This advancement was principally prompted by cancer cells' escape of immune regulation and the tumor's subsequent resistance to traditional therapy. Photodynamic therapy (PDT) has shown potential as a cancer treatment. It is less intrusive, more focused, and less damaging to normal cells and tissues. It entails the employment of a photosensitizer (PS) and a specific wavelength of light to create reactive oxygen species. Recently, an increasing number of studies have shown that PDT combined with immunotherapy improves the effect of tumor drugs and reduces tumor immune escape, improving the prognosis of breast cancer patients. Therefore, we objectively evaluate strategies for their limitations and benefits, which are critical to improving outcomes for breast cancer patients. In conclusion, we offer many avenues for further study on tailored immunotherapy, such as oxygen-enhanced PDT and nanoparticles.

Immunotherapy improves disease prognosis by affecting the tumor microenvironment: A bibliometric study

Background

Immunotherapy has shown great potential for the treatment of multiple cancer and has been proven to be closely related to the tumor microenvironment. This article reveals collaborations and interactions among authors, nations, organizations, and periodicals assesses the knowledge base, and discovers hot tendencies and new topics associated with immunotherapy-tumor microenvironment (TME) research.

Methods

This article utilized bibliometrics and visual methods to provide a comprehensive overview of immunotherapy-TME research. Our team retrieved the WoSCC for research and reviews associated with immunotherapy and the tumor microenvironment. VOSviewer and Citespace were primarily used for literature measurement and knowledge graph analysis.

Result

All English articles and reviews on cancer immunotherapy effectiveness were collected, and 1,419 academic journals with 53,773 authors from 7,008 institutions in 92 countries/regions were found. Publications associated with immunotherapy-TME research were stably increasing. Frontiers of Immunology (n = 722) published the most papers on immunotherapy-TME, and Cancer Research (n = 6761) was the top co-cited journal. The published journals and co-cited journals focused on cancer and immunology fields. The League of European Research Universities (n = 978), Harvard University (n = 528), and the University of Texas system (n = 520) were the most productive institutions. Yang Liu (n = 34) and Topalian (n = 1978) ranked first among the top 10 scholars and co-cited scholars. Simultaneously, immunotherapy-TME researchers were involved in active collaborations. Elements of TME, the foundation of immunotherapy, and the application of immunotherapy in cancers represented the three principal aspects of immunotherapy-TME research. The latest hot spots are drug resistance, prognosis prediction, efficacy prediction, and m⁶A. Nanomedicine and m⁶A may be future hot topics. Future research in immunotherapy-TME may be directed at discovering how m⁶A modification affects tumor development by altering the tumor microenvironment and exploring how to enhance response or reduce drug resistance to immunotherapy by reversing or mediating the physicochemical properties of the TME.

Conclusions

M⁶A and nanomedicine are also emerging hotspots in time zone diagrams with high centrality, and prognosis prediction using bioinformatics based on the development of prediction technology may be another future research hotspot.

Immunotherapy for HER2-Positive Breast Cancer: Clinical Evidence and Future Perspectives

Breast cancer is the most common malignancy among women worldwide, and HER2-positive breast cancer accounts for approximately 15% of all breast cancer diagnoses. The advent of HER2-targeting therapies has dramatically improved the survival of these patients, significantly reducing their risk of recurrence and death. However, as a significant proportion of patients ultimately develop resistance to these therapies, it is extremely important to identify new treatments to further improve their clinical outcomes. Immunotherapy has revolutionized the treatment and history of several cancer types, and it has already been approved as a standard of care for patients with triple-negative breast cancer. Based on a strong preclinical rationale, immunotherapy in HER2-positive breast cancer represents an intriguing field that is currently under clinical investigation. There is a close interplay between HER2-targeting therapies (both approved and under investigation) and the immune system, and several new immunotherapeutic strategies, including immune checkpoint inhibitors, CAR-T cells and therapeutic vaccines, are being studied in this disease. In this narrative review, we discuss the clinical evidence and the future perspectives of immunotherapy for patients with HER2-positive breast cancer.

Progress and pitfalls in the use of immunotherapy for patients with triple negative breast cancer

INTRODUCTION

Triple negative breast cancer (TNBC) is an area of high unmet medical need in terms of new effective treatment strategies. Although breast cancer is traditionally considered a 'cold' tumor type, TNBC is the most appropriate subtype for immunotherapeutic strategies; this is due to the high level of tumor infiltrating lymphocytes, PD-L1 expression and tumor mutational burden relative to other breast cancer subtypes.

AREAS COVERED

This review examines the use of immunotherapeutic strategies in early and advanced TNBC. The paper summarizes data on novel promising immunomodulatory approaches that have been explored in early phase trials and discusses the pitfalls and limitations often encountered in clinical research.

EXPERT OPINION

PD-1-blockade is approved for stage II/III TNBC and for first-line treatment of PD-L1-positive TNBC patients with metastatic disease and should be considered standard of care. However, question marks and difficulties remain; these include the identification of predictive biomarkers to select patients who benefit from the addition of PD1-blockade and the balance between efficacy and long-term toxicity for an individual patient. Numerous treatment combinations and new immunotherapeutic strategies beyond PD1 blockade are being evaluated, thus reflecting a promising evolution of a more personalized approach, and extended clinical benefit in TNBC.

Tackling Immune Targets for Breast Cancer: Beyond PD-1/PD-L1 Axis

The burden of breast cancer is imposing a huge global problem. Drug discovery research and novel approaches to treat breast cancer have been carried out extensively over the last decades. Although immune checkpoint inhibitors are showing promising preclinical and clinical results in treating breast cancer, they are facing multiple limitations. From an immunological perspective, a recent report highlighted breast cancer as an "inflamed tumor" with an immunosuppressive microenvironment. Consequently, researchers have been focusing on identifying novel immunological targets that can tune up the tumor immune microenvironment. In this context, several novel non-classical immune targets have been targeted to determine their ability to uncouple immunoregulatory pathways at play in the tumor microenvironment. This article will highlight strategies designed to increase the immunogenicity of the breast tumor microenvironment. It also addresses the latest studies on targets which can enhance immune responses to breast cancer and discusses examples of preclinical and clinical trial landscapes that utilize these targets.

The Multifactorial Role of PARP-1 in Tumor Microenvironment

Poly(ADP-ribose) polymerases (PARPs), represent a family of 17 proteins implicated in a variety of cell functions; some of them possess the enzymatic ability to synthesize and attach poly (ADP-ribose) (also known as PAR) to different protein substrates by a post-translational modification; PARPs are key components in the cellular response to stress with consequences for different physiological and pathological events, especially during neoplasia. In recent years, using PARP inhibitors as antitumor agents has raised new challenges in understanding their role in tumor biology. Notably, the function of PARPs and PAR in the dynamic of tumor microenvironment is only starting to be understood. In this review, we summarized the conclusions arising from recent studies on the interaction between PARPs, PAR and key features of tumor microenvironment such as hypoxia, autophagy, tumor initiating cells, angiogenesis and cancer-associated immune response.

Growth pattern can be used as a new characteristic to predict malignancy in breast cancer

BACKGROUND

To date, anatomic tumor length is a key criterion for cancer staging and can be used to evaluate the effectiveness of therapies. This article describes growth pattern that can be used as a new characteristic to represent disease burden and tumor features and predict lymphatic metastasis.

METHODS

Patients with breast cancer were included in this 10-year (1999-2008) hospital-based multicenter retrospective study. The pathologic length/height ratio was used to illustrate the correlation between tumor features, behaviors and treatments in breast malignancies. The most appropriate ratio was chosen based on the comprehensive evaluation of p value and changing trend of each characteristic.

RESULTS

The sample consisted of 4211 women diagnosed with breast cancer. Among them, 2037 patients with complete pathologic length, width and height information were included in the final analysis. There were 2.34 ± 4.77 metastatic lymph nodes for spheroid tumors and 3.21 ± 5.82 for ellipsoid tumors when the cutoff point was 2. In addition, the proportion of ellipsoidal tumors gradually increased from 54.36 to 56.67% in the upper outer quadrant (UOQ) and from 6.7 to 9.03% in the central region with an increase in the cutoff point. The proportion of ER + PR + ellipsoid tumors significantly decreased from 50.1 to 45.35% and that of ER-PR ellipsoid tumors significantly increased from 32.73 to 36.24% with an increase in the cutoff point. Additionally, the best length/weight ratio to distinguish spheroid and ellipsoid tumors was 2.

CONCLUSION

This study described for the first time how growth pattern is correlated with tumor malignancy and how it influences the selection of therapeutic strategies for patients.

Bioinformatic profiling of prognosis-related genes in the breast cancer immune microenvironment

In the microenvironment of breast cancer, immune cell infiltration is associated with an improved prognosis. To identify immune-related prognostic markers and therapeutic targets, we determined the lymphocyte-specific kinase (LCK) metagene scores of samples from breast cancer patients in The Cancer Genome Atlas. The LCK metagene score correlated highly with other immune-related scores, as well as with the clinical stage, prognosis and tumor suppressor gene mutation status (BRCA2, TP53, PTEN) of patients in the four breast cancer subtypes. A weighted gene co-expression network analysis was performed to detect representative genes from LCK metagene-related gene modules. In two of these modules, the levels of the co-expressed genes correlated highly with LCK metagene levels, so we conducted an enrichment analysis to discover their functions. We also identified differentially expressed genes in samples with high and low LCK metagene scores. By examining the overlapping results from these analyses, we obtained 115 genes, and found that 22 of them were independent predictors of overall survival in breast cancer patients. These genes were validated for their prognostic and diagnostic value with external data sets and paired tumor and non-tumor tissues. The genes identified herein could serve as diagnostic/prognostic markers and immune-related therapeutic targets in breast cancer.

CXCR4 and CXCR3 are two distinct prognostic biomarkers in breast cancer: Database mining for CXCR family members

CXC chemokine receptors (CXCRs) and chemokines are involved in tissue development and homeostasis, including in cancer development and progression. To date, seven CXCRs have been identified. However, the expression of CXCRs and their influence on the occurrence and development of breast cancer (BC) requires further investigation. In the present study, mRNA expression levels of the seven CXCRs were compared between normal tissues and several cancer types using the Oncomine database. Highly expressed CXCRs were selected and the expression levels of these CXCRs were examined in different subtypes of BC using the Gene Expression-Based Outcome for Breast Cancer database. Finally, the prognostic value of these CXCRs was examined using Kaplan-Meier plotter. It was found that, compared with normal controls, transcripts of CXCR4 and CXCR3 were significantly overexpressed in BC samples compared with other CXCRs. Survival analysis showed that high expression of CXCR4 promoted the recurrence of BC but had no impact on overall survival (OS), while a high level of CXCR3 transcript expression was significantly associated with increased survival in patients with BC. With regards to different subtypes of BC, the present study revealed that high CXCR4 transcript expression was significantly associated with both longer relapse-free survival and OS only in basal-like BC. Furthermore, CXCR4 promoted chemosensitivity in patients with basal-like BC and induced resistance against endocrine therapy for patients with luminal A BC. Thus, CXCR4 and CXCR3 are two distinct prognostic biomarkers and further studies are required.

The application of nanotechnology in enhancing immunotherapy for cancer treatment: current effects and perspective

Cancer immunotherapy is emerging as a promising treatment modality that suppresses and eliminates tumors by re-activating and maintaining the tumor-immune cycle, and further enhancing the body's anti-tumor immune response. Despite the impressive therapeutic potential of immunotherapy approaches such as immune checkpoint inhibitors and tumor vaccines in pre-clinical and clinical applications, the effective response is limited by insufficient accumulation in tumor tissues and severe side-effects. Recent years have witnessed the rise of nanotechnology as a solution to improve these technical weaknesses due to its inherent biophysical properties and multifunctional modifying potential. In this review, we summarized and discussed the current status of nanoparticle-enhanced cancer immunotherapy strategies, including intensified delivery of tumor vaccines and immune adjuvants, immune checkpoint inhibitor vehicles, targeting capacity to tumor-draining lymph nodes and immune cells, triggered releasing and regulating specific tumor microenvironments, and adoptive cell therapy enhancement effects.

Overexpression of Smac by an Armed Vesicular Stomatitis Virus Overcomes Tumor Resistance

Despite reports of successful clinical cases, many tumors appear to resist infection by oncolytic viruses (OVs). To circumvent this problem, an armed vesicular stomatitis virus was constructed by inserting a transgene to express Smac/DIABLO during virus infection (VSV-S). Endogenous Smac in HeLa cells was diminished during wtVSV infection, whereas the Smac level was enhanced during VSV-S infection. Apoptosis was readily induced by VSV-S, but not wtVSV, infection. More importantly, the tumor volume was reduced to a larger extent when xenografts of 4T1 cells in BALB/c mice and OV-resistant T-47D cells in nude mice were intratumorally injected with VSV-S. VSV-S represents a novel mechanism to overcome tumor resistance, resulting in more significant tumor regression due to enhanced apoptosis.

Cryoablation and immunotherapy: an overview of evidence on its synergy

Cancer cells can escape the immune system by different mechanisms. The evasion of cancer cells from immune surveillance is prevented by immune checkpoint inhibitors, allowing the patient’s own immune system to attack their cancer. Immune checkpoint inhibitors have shown improvement in overall survival for melanoma, lung cancer and renal cell carcinoma in clinical trials. Unfortunately, not all patients respond to this therapy.

In cancer management, percutaneous ablation techniques are well established for both cure and local control of many tumour types. Cryoablation of the tumour tissue results in cell destruction by freezing. Contrary to heat-based ablative modalities, cryoablation induces tumour cell death by osmosis and necrosis. It is hypothesised that with necrosis, the intracellular contents of the cancer cells stay intact allowing the immune system to induce an immune-specific reaction. This immune-specific reaction can, in theory, also affect cancer cells outside the ablated tissue, known as the abscopal effect. Unfortunately, this effect is rarely observed, but when cryoablation is combined with immunotherapy, the effect of both therapies may be enhanced. Although several preclinical studies demonstrated a synergistic effect between cryoablation and immunotherapy, prospective clinical trials are needed to prove this clinical benefit for patients. In this review, we will outline the current evidence for the combination of cryoablation with immunotherapy to treat cancer.

Immunotherapy in breast cancer: Current status and future directions

Breast cancer, one of the leading causes of death in women in the United States, challenges therapeutic success in patients due to tumor heterogeneity, treatment resistance, metastasis and disease recurrence. Knowledge of immune system involvement in normal breast development and breast cancer has led to extensive research into the immune landscape of breast cancer and multiple immunotherapy clinical trials in breast cancer patients. However, poor immunogenicity and T-cell infiltration along with heightened immunosuppression in the tumor microenvironment have been identified as potential challenges to the success of immunotherapy in breast cancer. Oncodrivers, owing to their enhanced expression and stimulation of tumor cell proliferation and survival, present an excellent choice for targeted immunotherapy development in breast cancer. Loss of anti-tumor immune response specific to oncodrivers has been reported in breast cancer patients as well. Dendritic cell vaccines have been tested for their efficacy in generating anti-tumor T-cell response against specific tumor-associated antigens and oncodrivers and have shown improved survival outcome in patients. Here, we review the current status of immunotherapy in breast cancer, focusing on dendritic cell vaccines and their therapeutic application in breast cancer. We further discuss future directions of breast cancer immunotherapy and potential combination strategies involving dendritic cell vaccines and existing chemotherapeutics for improved efficacy and better survival outcome in breast cancer.

Moving Breast Cancer Therapy up a Notch

Breast cancer is the second most common malignancy, worldwide. Treatment decisions are based on tumor stage, histological subtype, and receptor expression and include combinations of surgery, radiotherapy, and systemic treatment. These, together with earlier diagnosis, have resulted in increased survival. However, initial treatment efficacy cannot be guaranteed upfront, and these treatments may come with (long-term) serious adverse effects, negatively affecting a patient's quality of life. Gene expression-based tests can accurately estimate the risk of recurrence in early stage breast cancers. Disease recurrence correlates with treatment resistance, creating a major need to resensitize tumors to treatment. Notch signaling is frequently deregulated in cancer and is involved in treatment resistance. Preclinical research has already identified many combinatory therapeutic options where Notch involvement enhances the effectiveness of radiotherapy, chemotherapy or targeted therapies for breast cancer. However, the benefit of targeting Notch has remained clinically inconclusive. In this review, we summarize the current knowledge on targeting the Notch pathway to enhance current treatments for breast cancer and to combat treatment resistance. Furthermore, we propose mechanisms to further exploit Notch-based therapeutics in the treatment of breast cancer.

BLT2, a leukotriene B4 receptor 2, as a novel prognostic biomarker of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is considered to be a notorious type of cancer due to its aggressive metastatic potential and poor prognosis. Recent evidence suggests that BLT2, a low-affinity LTB₄ receptor is critically associated with the phenotypes of TNBC cells, including invasion, metastasis, and survival. Furthermore, in a group of 545 breast cancer patients with metastasis, we observed that the high-BLT2 subgroup had a lower disease-free-survival rate than the low-BLT2 subgroup. Thus, we theorized that anti-BLT2 strategies could facilitate the development of new therapies used for TNBC. This review focuses on recent discoveries regarding BLT2 and its roles in as a novel prognostic biomarker in TNBC.

Advances in the use of PARP inhibitor therapy for breast cancer

Poly-ADP-ribose polymerase 1 (PARP-1) and PARP-2 are DNA damage sensors that are most active during S-phase of the cell cycle and that have wider-reaching roles in DNA repair than originally described. BRCA1 and BRCA2 (Breast Cancer) proteins are involved in homologous recombination repair (HRR), which requires a homologous chromosome or sister chromatid as a template to faithfully repair DNA double-strand breaks. The small-molecule NAD+ mimetics, olaparib, niraparib, rucaparib, veliparib, and talazoparib, inhibit the catalytic activity of PARP-1 and PARP-2 and are currently being studied in later-stage clinical trials. PARP inhibitor clinical trials have predominantly focused on patients with breast and ovarian cancer with deleterious germline BRCA1 and BRCA2 mutations (gBRCA1/2+) but are now expanding to include cancers with known, suspected, or more-likely-than-not defects in homologous recombination repair. In ovarian cancer, this group also includes women whose cancers are responsive to platinum therapy. Olaparib was FDA-approved in January 2018 for the treatment of gBRCA1/2+ metastatic breast cancers. gBRCA1+ predisposes women to develop triple-negative breast cancers, while women with gBRCA2+ tend to develop hormone-receptor-positive, human epidermal growth factor receptor 2 negative breast cancers. Although PARP inhibitor monotherapy strategies seem most effective in cancers with homologous recombination repair defects, combination strategies may allow expansion into a wider range of cancers. By interfering with DNA repair, PARP inhibitors essentially sensitize cells to DNA-damaging chemotherapies and radiation therapy. Certainly, one could also consider expanding the utility of PARP inhibitors beyond gBRCA1/2+ cancers by causing DNA damage with cytotoxic agents in the presence of a DNA repair inhibitor. Unfortunately, in numerous phase I clinical trials utilizing a combination of cytotoxic chemotherapy at standard doses with dose-escalation of PARP inhibitors, there has generally been failure to reach monotherapy dosages of PARP inhibitors due to myelosuppressive toxicities. Strategies utilizing angiogenesis inhibitors and immune checkpoint inhibitors are generally not hindered by additive toxicities, though the utility of combining PARP inhibitors with treatments that have not been particularly effective in breast cancers somewhat tempers enthusiasm. Finally, there are combination strategies that may serve to mitigate resistance to PARP inhibitors, namely, upregulation of the intracellular PhosphoInositide-3-kinase, AK thymoma (protein kinase B), mechanistic target of rapamycin (PI3K-AKT-mTOR) pathway, or perhaps are more simply meant to interfere with a cell growth pathway heavily implicated in breast cancers while administering relatively well-tolerated PARP inhibitor therapy.