Pembrolizumab monotherapy for previously treated metastatic triple-negative breast cancer: cohort A of the phase II KEYNOTE-086 study

Fundamental knowledge and research regarding the role of immunity in triple-negative breast cancer from 2014-2024: A bibliometric analysis

Immunity has vital research value and promising applications in triple-negative breast cancer (TNBC). Nevertheless, few bibliometric analyses have systematically investigated this area. This study aimed to comprehensively review the collaboration and impact of countries, institutions, authors, and journals on the role of immunity in TNBC from a bibliometric perspective, evaluate the keyword co-occurrence of the knowledge structure, and identify hot trends and emerging topics. Articles and reviews related to immunity in TNBC were retrieved from the Web of Science core collection using subject search. A bibliometric study was conducted primarily using CiteSpace and VOSviewer. A total of 3,104 articles and reviews were included from January 1, 2014, through December 31, 2024. The number of articles on immunization in TNBC is rising. These publications are mainly from 415 institutions in 82 countries, led by China and the USA. Among these publications, Lajos Pusztai published the most papers, while Peter Schmid was co-cited the most. The most productive journals focused on molecular biology, biological immunology, and clinical medicine. Furthermore, co-citation analysis revealed that tumor microenvironment, biomarkers, and immune checkpoint inhibitors are current and developing research areas. The keywords "immunotherapy" and "nanoparticles" are also likely to be new trends and focal points for future research. This study adopted bibliometric and visualization methods to provide a comprehensive review of the research on immunization in TNBC. This article will help researchers better understand the dynamic evolution of the role of immunity in TNBC and identify areas for future research.

Why combine and why neoadjuvant? Tumor immunological perspectives on chemoimmunotherapy in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype characterized by limited targeted therapies and high recurrence rates. While immune checkpoint inhibitors (ICIs) have shown promise, their efficacy as monotherapy is limited. Clinically, ICIs demonstrate significant benefit primarily when combined with chemotherapy, particularly in the neoadjuvant setting for early-stage TNBC, which yields superior outcomes compared to adjuvant therapy. This review elucidates the tumor immunological principles underlying these observations. We discussed how the suppressive tumor microenvironment (TME), progressive T cell exhaustion, and associated epigenetic scarring constrain ICI monotherapy effectiveness. Crucially, we highlight the immunological advantages of the neoadjuvant approach: the presence of the primary tumor provides abundant antigens, and intact tumor-draining lymph nodes (TDLNs) act as critical sites for ICI-mediated priming and expansion of naïve and precursor exhausted T cells. This robust activation within TDLNs enhances systemic anti-tumor immunity and expands the T cell repertoire, a process less effectively achieved in the adjuvant setting after tumor resection. These mechanisms provide a strong rationale for the improved pathological complete response (pCR) rates and event-free survival observed with neoadjuvant chemoimmunotherapy, as demonstrated in trials like KEYNOTE-522. We further explore the implications for adjuvant therapy decisions based on treatment response, the challenges of ICI resistance, the need for predictive biomarkers, management of immune-related adverse events (irAEs), and future therapeutic directions. Understanding the dynamic interplay between chemotherapy, ICIs, T cells, and the TME, particularly the role of TDLNs in the neoadjuvant context, is essential for optimizing immunotherapy strategies and improving outcomes for patients with TNBC.

Nicotine-driven enhancement of tumor malignancy in triple-negative breast cancer via additive regulation of CHRNA9 and IGF1R

Cigarette smoking is a significant risk factor for cancer development with complex mechanisms. This study aims to investigate the impact of nicotine exposure on the regulation of stemness- and metastasis-related properties via cholinergic receptor nicotinic alpha 9 subunit (CHRNA9) and insulin-like growth factor-1 receptor (IGF1R) and to evaluate their therapeutic potential in triple-negative breast cancer (TNBC). We performed Kaplan-Meier survival analysis of public databases and revealed that high expression of CHRNA9, IGF1R signaling molecules, and stemness genes was significantly associated with poor recurrence-free survival (RFS) and distant metastasis-free survival (DMFS) in TNBC samples. Additionally, we examined two patient cohorts to determine the clinical associations between the expression levels of different genes (n = 67) and proteins (n = 42) and showed a strong positive correlation between the expression levels of CHRNA9, IGF1R signaling molecules, and stemness markers POU5F1/NANOG in tumor tissues. We carried out nicotine treatment and knockdown of CHRNA9 and IGF1R in TNBC cells to identify the effects on stemness-related properties in vitro. Furthermore, primary and secondary metastatic in vivo animal models were examined using micro-computed tomography (μCT) screening and in situ hybridization with a human Alu probe to detect tumor cells. Nicotine was found to upregulate the expression of CHRNA9, POU5F1, and IGF1R, influencing stemness- and metastasis-related properties. Knockdown of CHRNA9 expression attenuated nicotine-induced stemness-related properties in a TNBC cell model. Furthermore, knockdown of IGF1R expression significantly alleviated nicotine/CHRNA9-induced stemness features and cancer cell metastasis in cell cultures and lung metastatic mouse models. These results demonstrate that nicotine triggers IGF1R signaling, thereby enhancing stemness-related properties, cell migration, invasion, and tumor metastasis, resulting in a poorer prognosis for patients with TNBC. These findings highlight IGF1R as a promising therapeutic target for reducing stemness and metastasis in TNBC patients exposed to environmental nicotine. © 2025 The Pathological Society of Great Britain and Ireland.

Immunotherapy in Triple-Negative Breast Cancer

Currently, immunotherapy has led to a paradigmatic shift in the treatment of many cancer types, including triple-negative breast cancer. Immunotherapy increases the efficacy of the immune system in treating cancer, with a durable effect due to immunologic memory. The PD-1 inhibitor, pembrolizumab, combined with neoadjuvant chemotherapy, improved event-free survival and is a new standard of care for patients with high-risk, early stage triple-negative breast cancer (TNBC), regardless of tumor PD-L1 expression. For metastatic TNBC, pembrolizumab combined with chemotherapy is a new standard of care for first-line therapy for PD-L1+ metastatic TNBC, and it improves overall survival. The PD-L1 inhibitor, atezolizumab, combined with nab-paclitaxel, is also approved for first-line treatment of metastatic PD-L1+ TNBC. The aim of this review is to examine the existing evidence and ongoing studies on immunotherapy in patients with early stage and metastatic triple-negative breast cancer (TNBC), including new combination strategies with several drugs, such as chemotherapy, targeted therapy, or radiation and to discuss immune checkpoint inhibitor (ICI) applications and the possibility of emerging strategies in different TNBC stages.

CDC34 suppresses macrophage phagocytic activity and predicts poor response to immune checkpoint inhibitor in cancers

The cell division cycle 34 (CDC34) is an E2 ubiquitin-conjugating enzyme that is required for proteasomal degradation of substrate proteins, and is able to stabilize proteins including the epidermal growth factor receptor to promote lung carcinogenesis. Here, we conducted a pan-cancer analysis of CDC34 in The Cancer Genome Atlas datasets, and found its high expression in breast cancer and negative association with patient outcomes. Analysis of single-cell RNA-sequencing data revealed a negative role of CDC34 in macrophage phagocytotic activity for cancer cells. CDC34 stabilized hypoxia-inducible factor 1α (HIF1α) and transcriptionally upregulated CD47 in cancer cells to evade phagocytosis by macrophages. Inhibition of CDC34 inhibited tumor growth and synergized with anti-PD-L1 antibody in murine models. CDC34 was positively associated with CD47 and negatively associated with CD8+ granzyme B+ T-cell infiltration in patient samples, and patients with co-overexpression of CDC34 and CD47 had markedly poorer prognosis compared to those with high expression of either marker alone. In pre-treatment tumor samples, non-responders to immunotherapy exhibited significantly higher CDC34 levels and reduced CD8+ T-cell infiltration compared to responders. These findings indicated that CDC34 is critical to immune evasion and could be a potential therapeutic target for those resistant to immune checkpoint inhibitors.

Immunotherapy in breast cancer: current landscape and emerging trends

Breast cancer remains one of the most prevalent malignancies worldwide, underscoring an urgent need for innovative therapeutic strategies. Immunotherapy has emerged as a transformative frontier in this context. In triple-negative breast cancer (TNBC), the combination of immunotherapy based on PD-1/PD-L1 immune checkpoint inhibitors (ICIs) with chemotherapy has proven efficacious in both early and advanced clinical trials. These encouraging results have led to the approval of ICIs for TNBC, opening up new therapeutic avenues for challenging-to-treat patient populations. Furthermore, a multitude of ongoing trials are actively investigating the efficacy of immunotherapy-based combinations, including ICIs in conjunction with chemotherapy, targeted therapy and radiation therapy, as well as other novel strategies such as bispecific antibodies, CAR-T cells and cancer vaccines across all breast cancer subtypes, including HR-positive/HER2-negative and HER2-positive disease. This review provides a comprehensive overview of current immunotherapeutic approaches in breast cancer, highlighting pivotal findings from recent clinical trials and the potential impact of these advancements on patient outcomes.

Pembrolizumab in Combination with Binimetinib in Patients with Unresectable Locally Advanced or Metastatic Triple-Negative Breast Cancer

PURPOSE

Activation of the RAS/MAPK pathway is associated with reduced tumor-infiltrating lymphocytes and poor outcomes in triple-negative breast cancer. Previous studies demonstrated that inhibition of the MAPK pathway with a MEK inhibitor is synergistic with immune checkpoint inhibitors.

PATIENTS AND METHODS

We conducted a phase I/II trial of pembrolizumab and binimetinib in patients with metastatic triple-negative breast cancer with ≤3 prior lines of therapy. There were two dose levels (DL) with binimetinib at 45 mg at DL 0 and 30 mg at DL -1.

RESULTS

The recommended phase II dose was the standard dose of pembrolizumab with binimetinib 30 mg twice daily. The objective response rate (ORR) was 30.4%, with a numerically higher ORR in patients without liver metastasis at 45.5%. Among patients who achieved objective responses, 80% had a duration of response >12 months and ongoing even after stopping treatment (5.4-69.0 months). Patients with PD-L1-positive tumors (modified proportion score ≥10) were more likely to respond with an ORR of 66.7%. However, clinical benefit was observed in 25% of patients with PD-L1-negative tumors. Consistent with preclinical studies, four of six patients with clinical benefit had either increased PD-L1 or decreased p-ERK expressions in serial circulating cancer-associated macrophage-like cells after starting binimetinib.

CONCLUSIONS

Pembrolizumab and binimetinib at 30 mg are safe with manageable toxicities. Promising activity was observed in patients without liver metastases. Future larger clinical trials are warranted to further evaluate the efficacy of this chemotherapy-free combination.

Advances in TIL therapy: Expanding the horizons beyond melanoma

Tumor-infiltrating lymphocyte (TIL) therapy represents a breakthrough in solid tumor treatment, addressing unmet needs for patients with limited options. While its efficacy is established in advanced melanoma, TIL therapy shows early promise in non-small cell lung cancer, breast cancer, gynecological cancers, and head and neck cancers. However, challenges such as reduced T cell infiltration, lower tumor mutational burden (TMB), immunosuppressive tumor microenvironments (TME), and toxicity associated with the TIL therapy regimen hinder its broader application in these patient groups, compared with melanoma. To address these challenges, new approaches focus on the selection of tumor-reactive TIL, optimization of TIL expansion, combination of immune checkpoint inhibitors with TIL therapy to counteract immunosuppressive microenvironments, and genetic modification of TIL to enhance persistence and functionality. Larger clinical trials are essential to validate these innovations and standardize protocols. With continued advancements, TIL therapy has the potential to redefine the treatment landscape for advanced solid cancers.

Phase 2 trial of imprime and pembrolizumab immunotherapy in metastatic triple negative breast cancer patients who have progressed beyond first line chemotherapy

The Phase 2 IMPRIME 1 study evaluated the combination of the pathogen-associated molecular pattern (PAMP) Imprime with the immune checkpoint inhibitor (ICI) pembrolizumab as second or later line of treatment (2 L+) for patients with metastatic triple-negative breast cancer (mTNBC). Eligible patients with mTNBC received weekly Imprime (4 mg/kg) intravenously in combination with pembrolizumab (200 mg every 3 weeks). Primary endpoints were overall response rate (ORR) and safety. Secondary endpoints included disease control rate (DCR), duration of response (DoR), progression free survival (PFS), and overall survival (OS). Exploratory endpoints included correlations between immune cell activation markers in tumor tissues and blood and response to therapy. Of the 42 evaluable patients, six had a response (one complete, five partial), with an ORR of 14.3% by RECIST v1.1. Median PFS was 2.7 months, median OS was 16.4 months, and DCR was 54.8%, with responders achieving a median DoR of 15.2 months. Therapy was generally well tolerated and resulted in an increase of immune activation markers, with higher levels of activation in peripheral blood associated with response and improved survival. The combination of Imprime and pembrolizumab was safe and demonstrated immune activation in tumor tissues and peripheral blood in patients with TNBC. Improved response rates were observed compared to historical studies of ICI monotherapy in similar patient populations. Study number (ClinicalTrials.gov trial registration): NCT02981303.

Advances in mRNA vaccine therapy for breast cancer research

Breast cancer represents the most prevalent cancer among women globally, constituting approximately 30% of newly diagnosed female malignancies and serving as the second leading cause of cancer-related mortality, accounting for 11.6% of deaths. Despite notable advancements in survival rates and quality of life for breast cancer patients over recent decades-achieved through interventions such as surgery, chemotherapy, radiotherapy, and endocrine therapy-there remains an urgent need for novel therapeutic strategies. This necessity arises from challenges associated with recurrence, metastasis, and drug resistance. The COVID-19 pandemic has accelerated the development of Messenger RNA (mRNA) vaccines at an unprecedented pace, and as a novel form of precision immunotherapy, mRNA vaccines are increasingly being recognized for their potential in cancer treatment. mRNA vaccines efficiently produce antigens within the cytoplasm, specifically activating the immune system to target tumor cells while minimizing the risk of T-cell tolerance. Therefore, mRNA vaccines have emerged as a promising approach in cancer immunotherapy. This review systematically examines the principles, mechanisms, advantages, key targets, and recent progress in mRNA vaccine therapy for breast cancer. Furthermore, it discusses current challenges and suggests potential directions for future research.

ADAMs contribute to triple negative breast cancer via mTORC1 pathway: targeting ADAM-mTOR axis improves efficacy

Breast cancer is the most frequently diagnosed cancer globally and the second leading cause of cancer-related deaths in American women. Triple-negative breast cancer (TNBC) lacks estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Thus, fewer targeting therapies are available for this most aggressive subtype. The A Disintegrin and Metalloproteinase (ADAM) family plays a vital role in cancer pathophysiology. Previous studies focused on single ADAM members. However, none of these have entered into the clinical arena as diagnostics or therapeutics for breast cancer. In this study, we demonstrate the upregulation of a panel of ADAM members in TNBC, and overexpression of all the individual ADAMs tested are correlated with poor patient survival, making it unlikely that targeting a single ADAM member would be effective. Reverse-phase protein array and multiplexed immunofluorescence revealed that ADAM10/15/17 expression was associated with activated mTOR signaling. Individual knockdown of ADAM10, ADAM15, or ADAM17 modestly reduced mTOR signaling, cellular proliferation and survival. However, the concurrent knockdown of the three ADAMs drastically decreased mTOR signaling and cellular aggressiveness. Consistently, combined targeting of ADAMs and mTOR increased inhibitory efficacy compared to monotherapy in ADAM-mTOR-activated tumor growth and invasion in vitro and in immunodeficient and immunocompetent mice. These results establish a functional link between ADAMs and activation of mTOR signaling, suggesting the ADAM-mTOR axis as a therapeutic target and biomarker for ADAM-enriched TNBC and, potentially, other tumor lineages with high ADAM activity.

Current Status of Immune Checkpoint Inhibitors and Treatment Responsive Biomarkers for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC), accounting for about 10%-20% of all breast cancer cases, is characterized by its aggressive nature, high recurrence rates, and poor prognosis. Unlike other breast cancer subtypes, TNBC lacks hormone receptors and specific molecular targets, limiting therapeutic options. In recent years, immune checkpoint inhibitors (ICIs) have shown promise in treating TNBC by targeting immune evasion mechanisms. Despite these advancements, several issues remain unresolved, including low response rates in programmed cell death ligand 1 (PD-L1) negative TNBC subtypes and the challenge of predicting which patients will benefit from ICIs. Consequently, there is growing interest in identifying reliable biomarkers beyond PD-L1 expression. This review synthesizes recent studies to provide a comprehensive perspective on ICI therapy in TNBC, clarifying the status of single-agent ICI therapies and combination strategies, emphasizing the need for further research into biomarkers. These insights provide clues for more personalized and effective treatment approaches, ultimately aiming to improve clinical outcomes for patients with TNBC.

Harnessing Tumor-Infiltrating Lymphocytes in Triple-Negative Breast Cancer: Opportunities and Barriers to Clinical Integration

Triple-negative breast cancer (TNBC) continues to present a therapeutic challenge due to the fact that by definition, these cancer cells lack the expression of targetable receptors. Current treatment options include cytotoxic chemotherapy, antibody-drug conjugates (ADC), and the PD-1 checkpoint inhibitor, pembrolizumab. Due to high rates of recurrence, current guidelines for early-stage TNBC recommend either multi-agent chemotherapy or chemo-immunotherapy in all patients other than those with node-negative tumors < 0.5 cm. This approach can lead to significant long-term effects for TNBC survivors, driving a growing interest in de-escalating therapy where appropriate. Tumor infiltrating lymphocytes (TILs) represent a promising prognostic and predictive biomarker for TNBC. These diverse immune cells are present in the tumor microenvironment and within the tumor itself, and multiple retrospective studies have demonstrated that a higher number of TILs in early-stage TNBC portends a favorable prognosis. Research has also explored the potential of TIL scores to predict the response to immunotherapy. However, several barriers to the widespread use of TILs in clinical practice remain, including logistical and technical challenges with the scoring of TILs and lack of prospective trials to validate the trends seen in retrospective studies. This review will present the current understanding of the role of TILs in TNBC and discuss the future directions of TIL research.

Reprogramming the breast tumor immune microenvironment: cold-to-hot transition for enhanced immunotherapy

This review discusses reprogramming the breast tumor immune microenvironment from an immunosuppressive cold state to an immunologically active hot state. A complex interplay is revealed, in which the accumulation of metabolic byproducts-such as lactate, reactive oxygen species (ROS), and ammonia-is shown to impair T-cell function and promote tumor immune escape. It is demonstrated that the tumor microenvironment (TME) is dominated by immunosuppressive cytokines, including interleukin-10 (IL-10), transforming growth factorβ (TGFβ), and IL-35. Notably, IL-35 is produced by regulatory T cells and breast cancer cells. The conversion of conventional T cells into IL-35-producing induced regulatory T cells, along with the inhibition of pro-inflammatory cytokine secretion, contributes to the suppression of anti-tumor immunity. It is further demonstrated that key immune checkpoint molecules-such as PD-1, PDL1, CTLA-4, TIM-3, LAG-3, and TIGIT-are upregulated within the TME, leading to Tcell exhaustion and diminished immune responses. The blockade of these checkpoints is shown to restore T-cell functionality and is proposed as a strategy to convert cold tumors into hot ones with robust effector cell infiltration. The therapeutic potential of chimeric antigen receptor (CAR)T cell therapy is also explored, and targeting specific tumor-associated antigens, such as glycoproteins and receptor tyrosine kinases, is highlighted. It is suggested that CART cell efficacy can be enhanced by combining these cells with immune checkpoint inhibitors and other immunomodulatory agents, thereby overcoming the barriers imposed by the immunosuppressive TME. Moreover, the role of the microbiome in regulating estrogen metabolism and systemic inflammation is reviewed. Alterations in the gut microbiota are shown to affect the TME, and microbiome-based interventions are proposed as an additional means to facilitate the cold-to-hot transition. It is concluded that by targeting the metabolic and immunological pathways that underpin immune suppression-through combination strategies involving checkpoint blockade, CART cell therapies, and microbiome modulation-the conversion of the breast TME from cold to hot can be achieved. This reprogramming is anticipated to enhance immune cell infiltration and function, thereby improving the overall efficacy of immunotherapies and leading to better clinical outcomes for breast cancer patients.

Role of Tumor-Associated Macrophages in Breast Cancer Immunotherapy

Breast cancer (BC) is the second leading cause of death among women worldwide. Immunotherapy has become an effective treatment for BC patients due to the rapid development of medical technology. Considerable breakthroughs have been made in research, marking the beginning of a new era in cancer treatment. Among them, various cancer immunotherapies such as immune checkpoint inhibitors (ICIs), cancer vaccines, and adoptive cell transfer are effective and have good prospects. The tumor microenvironment (TME) plays a crucial role in determining the outcomes of tumor immunotherapy. Tumor-associated macrophages (TAMs) are a key component of the TME, with an immunomodulatory effect closely related to the immune evasion of tumor cells, thereby affecting malignant progression. TAMs also significantly affect the therapeutic effect of ICIs (such as programmed death 1/programmed death ligand 1 (PD-1/PD-L1) inhibitors). TAMs are composed of multiple heterogeneous subpopulations, including M1 phenotypes macrophages (M1) and M2 phenotypes macrophages (M2). Furthermore, they mainly play an M2-like role and moderate a variety of harmful consequences such as angiogenesis, immunosuppression, and metastasis. Therefore, TAMs have become a key area of focus in the development of tumor therapies. However, several tumor immunotherapy studies demonstrated that ICIs are effective only in a small number of solid cancers, and tumor immunotherapy still faces relevant challenges in the treatment of solid tumors. This review explores the role of TAMs in BC immunotherapy, summarizing their involvement in BC development. It also explains the classification and functions of TAMs, outlines current tumor immunotherapy approaches and combination therapies, and discusses the challenges and potential strategies for TAMs in immuno-oncology treatments.

Progress of PD-1/PD-L1 immune checkpoint inhibitors in the treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly heterogeneous cancer with substantial recurrence potential. Currently, surgery and chemotherapy are the main treatments for this disease. However, chemotherapy is often limited by several factors, including low bioavailability, significant systemic toxicity, inadequate targeting, and multidrug resistance. Immune checkpoint inhibitors (ICIs), including those targeting programmed death protein-1 (PD-1) and its ligand (PD-L1), have been proven effective in the treatment of various tumours. In particular, in the treatment of TNBC with PD-1/PD-L1 inhibitors, both monotherapy and combination chemotherapy, as well as targeted drugs and other therapeutic strategies, have broad therapeutic prospects. In addition, these inhibitors can participate in the tumour immune microenvironment (TIME) through blocking PD-1/PD-L1 binding, which can improve immune efficacy. This article provides an overview of the use of PD-1/PD-L1 inhibitors in the treatment of TNBC and the progress of multiple therapeutic studies. To increase the survival of TNBC patients, relevant biomarkers for predicting the efficacy of PD-1/PD-L1 inhibitor therapy have been explored to identify new strategies for the treatment of TNBC.

Nanosensitizer-assisted sonodynamic therapy for breast cancer

Breast cancer is the most commonly diagnosed cancer worldwide. Despite advancements in therapeutic modalities, its prognosis remains poor owing to complex clinical, pathological, and molecular characteristics. Sonodynamic therapy (SDT) is a promising approach for tumor elimination, using sonosensitizers that preferentially accumulate in tumor tissues and are activated by low-intensity ultrasound to produce reactive oxygen species. However, the clinical translation of SDT faces challenges, including the limited efficiency of sonosensitizers and resistance posed by the tumor microenvironment. The emergence of nanomedicine offers innovative strategies to address these obstacles. This review discusses strategies for enhancing the efficacy of SDT using sonosensitizers, including rational structural modifications, improved tumor-targeted enrichment, tumor microenvironment remodeling, and imaging-guided therapy. Additionally, SDT-based multimodal therapies, such as sono-chemotherapy, sono-immunotherapy, and sono-photodynamic therapy, and their potential applications in breast cancer treatment are summarized. The underlying mechanisms of SDT in breast cancer are briefly outlined. Finally, this review highlights current challenges and prospects for the clinical translation of SDT, providing insights into future advancements that may improve therapeutic outcomes for breast cancer.

Triple-negative breast cancer molecular subtypes and potential detection targets for biological therapy indications

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer associated with poor prognosis. While chemotherapy remains the conventional treatment approach, its efficacy is limited and often accompanied by significant toxicity. Advances in precision-targeted therapies have expanded treatment options for TNBC, including immunotherapy, poly (ADP-ribose) polymerase inhibitors, androgen receptor inhibitors, cell cycle-dependent kinase inhibitors, and signaling pathway inhibitors. However, the heterogeneous nature of TNBC contributes to variations in treatment outcomes, underscoring the importance of identifying intrinsic molecular subtypes for personalized therapy. Additionally, due to patient-specific variability, the therapeutic response to targeted treatments is inconsistent. This highlights the need to strategize patients based on potential therapeutic targets for targeted drugs to optimize treatment strategies. This review summarizes the classification strategies and immunohistochemical (IHC) biomarkers for TNBC subtypes, along with potential targets for identifying indications for targeted drug therapy. These insights aim to support the development of personalized treatment approaches for TNBC patients.

Efficacy and Safety of Immunochemotherapy in Advanced Triple-negative Breast Cancer: A Meta-analysis of Randomised Clinical Trials

AIMS

Based on the existing controversial clinical research results, this study conducted a comprehensive meta-analysis of relevant literature to clarify the benefits of immunochemotherapy (ICT)-which combines immune checkpoint inhibitors and chemotherapy (CT)-for patients with advanced triple-negative breast cancer (aTNBC).

MATERILAS AND METHODS

A thorough literature search was conducted up to February 15, 2024. Subsequently, meta-analyses were performed to aggregate hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS), odds ratios (ORs) for objective response rate (ORR) and relative risks (RRs) for adverse events (AEs).

RESULTS

Six randomised clinical trials (RCTs) involving 3,105 patients met the inclusion criteria. In comparison with CT, ICT yielded significant enhancements in PFS (HR, 0.80; 95%CI: 0.73-0.87), OS (HR, 0.87; 95%CI: 0.80-0.96), and ORR (OR, 1.34; 95%CI: 1.15-1.55) in the intention-to-treat population. However, ICT also exhibited an increase in grade ≥3 AEs (RR, 1.11; 95%CI: 1.04-1.19) and severe AEs (RR, 1.40; 95%CI: 1.18-1.66). Subgroup analyses revealed that ICT significantly improved PFS (HR, 0.67; 95%CI: 0.58-0.77), OS (HR, 0.75; 95%CI: 0.64-0.87), and ORR (OR, 1.47; 95%CI: 1.16-1.84) within the PD-L1-positive subgroup, whereas no statistically significant differences were detected for PD-L1-negative population.

CONCLUSION

ICT demonstrates superior efficacy over conventional CT in the treatment of aTNBC, albeit accompanied by heightened toxicity. Notably, the assessment of PD-L1 status may serve as a valuable biomarker in discerning aTNBC patients who are particularly predisposed to derive benefit from ICT.

PROSPERO NUMBER

CRD42024513270.

MHC-I upregulation by macbecin II in the solid tumors potentiates the effect of active immunotherapy

We aimed to restore MHC-I expression on the surface of solid tumors including breast cancer and melanoma cells to regain sensitivity to immunotherapy and suppress metastatic progression. We screened a natural compound library and identified macbecin II as a reagent that upregulates MHC-I expression and induces antigen-dependent cell death in pre-invasive and invasive breast cancer models. Furthermore, we employed active immunotherapy using engineered small extracellular vesicles from dendritic cells (DCs) as a tumor vaccine (IL2-ep13nsEV) in combination with macbecin II for personalized breast cancer treatment. We found that macbecin II induced MHC-I-dependent antigen presentation and that IL2-ep13nsEV synergized with macbecin II inducing cell death, reducing metastasis, and boosting immune cell infiltration. In addition, macbecin II potentiated the effects of anti-PD-1 immunotherapy in suppressing tumor growth and metastasis. Mechanistically, macbecin II upregulated MHC-I expression post-translationally by rescuing it from lysosomal degradation. Our findings revealed a strong efficacy of macbecin II in regulating MHC-I expression and following antigen-dependent cell death. Therefore, combining active immunotherapies and macbecin II represents an effective strategy to prevent growth and progression of solid tumors including breast cancer and melanoma.

Immunotherapy and its racial specificity for breast cancer treatment in Asia: a narrative review

Immunotherapy, including immune checkpoint inhibitors, adoptive cell therapy, cancer vaccines, and other modalities, represents a significant advancement in cancer treatment. Breast cancer, traditionally considered less amenable to immunotherapy, has demonstrated responsiveness to immunotherapy when combined with conventional treatment options. These integrative strategies enhance the effectiveness of immunotherapy, bringing hope to patients. Furthermore, precision therapies guided by predictive biomarkers refine the scope of breast cancer immunotherapy and broaden its advantages. Notably, it is essential to recognise the differences in breast cancer epidemiology, clinical outcomes, and molecular signatures between Asian populations and those in Europe and North America. These include a higher proportion of premenopausal patients and variation in subtype distribution and gene mutation profiles, underscoring the importance of considering racial specificity in immunotherapy. Clinical efforts in Asia, supported by ethnicity-specific studies, indigenous immunotherapeutic agents, and precision medicine informed by predictive biomarkers, provide tailored treatment options. This review aims to present an overview of breast cancer immunotherapy while address the racial specificity to inform its application for Asian patients.

New progress in imaging diagnosis and immunotherapy of breast cancer

Breast cancer (BC) is a predominant malignancy among women globally, with its etiology remaining largely elusive. Diagnosis primarily relies on invasive histopathological methods, which are often limited by sample representation and processing time. Consequently, non-invasive imaging techniques such as mammography, ultrasound, and Magnetic Resonance Imaging (MRI) are indispensable for BC screening, diagnosis, staging, and treatment monitoring. Recent advancements in imaging technologies and artificial intelligence-driven radiomics have enhanced precision medicine by enabling early detection, accurate molecular subtyping, and personalized therapeutic strategies. Despite reductions in mortality through traditional treatments, challenges like tumor heterogeneity and therapeutic resistance persist. Immunotherapies, particularly PD-1/PD-L1 inhibitors, have emerged as promising alternatives. This review explores recent developments in BC imaging diagnostics and immunotherapeutic approaches, aiming to inform clinical practices and optimize therapeutic outcomes.

The evolving landscape of genetic biomarkers for immunotherapy in primary and metastatic breast cancer

Background

Major advances have been achieved in the characterization of primary breast cancer genomic profiles. Limited information is available on the genomic profile of tumors originating from different metastatic locations in recurrent/metastatic (R/M) breast cancer, especially in Asian patients. This study aims to decipher the mutational profiles of primary and R/M breast cancer in Chinese patients using next-generation sequencing.

Methods

A total of 563 breast cancer patients were enrolled, and 590 tumor tissues and matched peripheral blood samples were collected and subjected to targeted sequencing with a panel of 1,021 cancer-related genes. The mutation spectrum, DNA damage response (DDR) genes, commonly altered signal pathways, and immunotherapy-related markers were compared between primary and R/M breast cancer. The molecular differences between our cohort and the Memorial Sloan Kettering Cancer Center (MSKCC) dataset were also explored.

Results

A total of 361 samples from primary and 229 samples from R/M breast cancer were analyzed. BRCA2, ATRX, and ATM were more frequently observed in R/M lesions among the 36 DDR genes. An ESR1 mutation and PD-L1 and PD-L2 amplification were enriched in R/M breast cancer (all p<0.05). Compared with the MSKCC dataset, we recruited more patients diagnosed at age 50 or younger and more patients with triple-negative breast cancer (TNBC) subtypes. The TNBC patients in our dataset had a higher percentage of PD-L1 amplification in metastasis tumors (p<0.05).

Conclusions

This study revealed the distinctive mutational features of primary and R/M tumors in Chinese breast cancer patients, which are different from those from Western countries. The enrichment of PD-L1 amplification in metastatic TNBC indicates the necessity to re-biopsy metastatic tumors for immunotherapy.

Molecular determinants of response to neoadjuvant pembrolizumab plus chemotherapy in patients with high-risk, early-stage, triple-negative breast cancer: exploratory analysis of the open-label, multicohort phase 1b KEYNOTE-173 study

BACKGROUND

The multicohort, open-label, phase 1b KEYNOTE-173 study was conducted to investigate pembrolizumab plus chemotherapy as neoadjuvant therapy for triple-negative breast cancer (TNBC). This exploratory analysis evaluated features of the tumor microenvironment that might be predictive of response.

METHODS

Cell fractions from 20 paired samples collected at baseline and after one cycle of neoadjuvant pembrolizumab prior to chemotherapy initiation were analyzed by spatial localization (tumor compartment, stromal compartment, or sum of tumor and stromal compartments [total tumor]) using three six-plex immunohistochemistry panels with T-cell, myeloid cell, and natural killer cell components. Area under the receiver operating characteristic curve (AUROC) was used to assess associations between immune subsets and gene expression signatures (T-cell-inflamed gene expression profile [TcellinfGEP] and 10 non-TcellinfGEP signatures using RNA sequencing) and pathologic complete response (pCR).

RESULTS

At baseline, six immune subsets quantitated within the tumor compartment showed AUROC with 95% CIs not crossing 0.5, including CD11c+ cells (macrophage and dendritic cell [DC]: AUROC, 0.85; 95% confidence interval [CI] 0.63-1.00), CD11c+/MHCII+/CD163-/CD68- cells (DC: 0.76; 95% CI, 0.53-0.99), CD11c+/MHCII-/CD163-/CD68- cells (nonactivated/immature DC: 0.80; 95% CI 0.54-1.00), and CD11c+/CD163+ cells (M2 macrophage: 0.77; 95% CI 0.55-0.99). Other associations with pCR included baseline CD11c+/MHCII-/CD163-/CD68- (nonactivated/immature DC) within the total tumor (AUROC, 0.76; 95% CI 0.51-1.00) and the baseline CD11c/CD3 ratio within the tumor compartment (0.75; 95% CI 0.52-0.98). Changes in immune subsets following one cycle of pembrolizumab were not strongly associated with pCR. Although T-cell associations were relatively weak, specific CD8 subsets trended toward association. The AUROC for discriminating pCR based on TcellinfGEP was 0.55 (95% CI 0.25-0.85); when detrended by TcellinfGEP, AUROC varied for the non-TcellinfGEP signatures. TcellinfGEP expression trended higher in responders than in nonresponders when evaluating pCR.

CONCLUSIONS

Myeloid cell populations within the tumor compartment at baseline and TcellinfGEP show a promising trend toward an association with pCR in a small subgroup of patients with early-stage TNBC treated with neoadjuvant pembrolizumab plus chemotherapy.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02622074; registration date, December 2, 2015.

Antitumor Research Based on Drug Delivery Carriers: Reversing the Polarization of Tumor-Associated Macrophages

The development of malignant tumors is a complex process that involves the tumor microenvironment (TME). An immunosuppressive TME presents significant challenges to current cancer therapies, serving as a key mechanism through which tumor cells evade immune detection and play a crucial role in tumor progression and metastasis. This impedes the optimal effectiveness of immunotherapeutic approaches, including cytokines, immune checkpoint inhibitors, and cancer vaccines. Tumor-associated macrophages (TAMs), a major component of tumor-infiltrating immune cells, exhibit dual functionalities: M1-like TAMs suppress tumorigenesis, while M2-like TAMs promote tumor growth and metastasis. Consequently, the development of various nanocarriers aimed at polarizing M2-like TAMs to M1-like phenotypes through distinct mechanisms has emerged as a promising therapeutic strategy to inhibit tumor immune escape and enhance antitumor responses. This Review covers the origin and types of TAMs, common pathways regulating macrophage polarization, the role of TAMs in tumor progression, and therapeutic strategies targeting TAMs, aiming to provide a comprehensive understanding and guidance for future research and clinical applications.

Sciatic nerve stimulation enhances NK cell cytotoxicity through dopamine signaling and synergizes immunotherapy in triple-negative breast cancer

AIMS

Triple-negative breast cancer (TNBC) has shown resistance to immunotherapy. Stimulating ProkR2-bearing sensory neurons of the sciatic nerve has been reported to regulate immune function by catecholamine release through the vagal-adrenal axis. We aimed to investigate the impact of sciatic nerve stimulation on anti-tumor immune responses and immunotherapy efficacy in TNBC.

METHODS

We implemented ProkR2-bearing neuron stimulation in a TNBC mouse model. Single-cell RNA sequencing, flow cytometry, and immunohistochemistry were employed to uncover alterations in the tumor immune microenvironment. Immune cell depletion and receptor inhibitors were used to verify the cellular and molecular mechanisms by which neurostimulation regulates anti-tumor immunity.

RESULTS

Sciatic nerve stimulation inhibited 4T1 tumor growth by activating natural killer (NK) cells in the tumor microenvironment. The D1-like dopamine receptor-cAMP-PKA-CREB signaling pathway is essential for enhanced NK cell cytotoxicity and tumor inhibition induced by neurostimulation. Neurostimulation upregulated tumor PD-L1 expression through IFN-gamma pathway. Combining sciatic nerve stimulation with anti-PD-1 therapy resulted in superior tumor control compared to either approach alone and demonstrated good safety.

CONCLUSIONS

This research addresses a long-standing gap in understanding neuro-immune regulation in cancer treatment, presenting a promising strategy for overcoming immunoresistance in TNBC.

Unveiling the role of MDH1 in breast cancer drug resistance through single-cell sequencing and schottenol intervention

This study utilizes single-cell RNA sequencing data to reveal the transcriptomic characteristics of breast cancer and normal epithelial cells. Nine significant cell populations were identified through stringent quality control and batch effect correction. Further classification of breast cancer epithelial cells based on the PAM50 method and clinical subtypes highlighted significant heterogeneity between triple-negative breast cancer (TNBC) and non-triple-negative breast cancer (NTNBC). The study also analyzed myeloid cells and tumor-infiltrating lymphocytes (TILs) within the breast cancer immune microenvironment, identifying 14 TIL subpopulations and assessing their proportion variations across different patients. The CellChat tool revealed a complex cellular communication network within the tumor microenvironment, showing notable differences in communication intensity and patterns between TNBC and NTNBC patients. Additionally, the key regulatory role of the senescence-associated gene MDH1 in breast cancer was confirmed, and its impact on drug sensitivity was explored. Finally, it was discovered that the phytosterol Schottenol inhibits breast cancer cell proliferation by downregulating MDH1 expression and enhances sensitivity to paclitaxel. These findings provide new insights into MDH1 as a therapeutic target and suggest Schottenol as a potential strategy to overcome breast cancer drug resistance.

Ultrasound genomics related mitochondrial gene signature for prognosis and neoadjuvant chemotherapy resistance in triple negative breast cancer

Background

Neoadjuvant chemotherapy (NAC) significantly enhances clinical outcomes in patients with triple-negative breast cancer (TNBC); however, chemoresistance frequently results in treatment failure. Consequently, understanding the mechanisms underlying resistance and accurately predicting this phenomenon are crucial for improving treatment efficacy.

Methods

Ultrasound images from 62 patients, taken before and after neoadjuvant therapy, were collected. Mitochondrial-related genes were extracted from a public database. Ultrasound features associated with NAC resistance were identified and correlated with significant mitochondrial-related genes. Subsequently, a prognostic model was developed and evaluated using the GSE58812 dataset. We also assessed this model alongside clinical factors and its ability to predict immunotherapy response.

Results

A total of 32 significant differentially expressed genes in TNBC across three groups indicated a strong correlation with ultrasound features. Univariate and multivariate Cox regression analyses identified six genes as independent risk factors for TNBC prognosis. Based on these six mitochondrial-related genes, we constructed a TNBC prognostic model. The model's risk scores indicated that high-risk patients generally have a poorer prognosis compared to low-risk patients, with the model demonstrating high predictive performance (p = 0.002, AUC = 0.745). This conclusion was further supported in the test set (p = 0.026, AUC = 0.718). Additionally, we found that high-risk patients exhibited more advanced tumor characteristics, while low-risk patients were more sensitive to common chemotherapy drugs and immunotherapy. The signature-related genes also predicted immunotherapy response with a high accuracy of 0.765.

Conclusion

We identified resistance-related features from ultrasound images and integrated them with genomic data, enabling effective risk stratification of patients and prediction of the efficacy of neoadjuvant chemotherapy and immunotherapy in patients with TNBC.

Optimal early endpoint for second-line or subsequent immune checkpoint inhibitors in previously treated advanced solid cancers: a systematic review

BACKGROUND

The administration of second-line or subsequent immune checkpoint inhibitors (ICIs) in previously treated patients with advanced solid cancers has been clinically investigated. However, previous clinical trials lacked an appropriate primary endpoint for efficacy assessment. This systematic review aimed to explore the most optimal early efficacy endpoint for such trials.

METHODS

Phase 2 or 3 clinical trials involving patients with advanced solid cancers with disease progression following standard first-line therapy receiving second-line or subsequent ICI administration, with adequate survival outcome data, were included from PubMed, Embase, Web of Science, and Cochrane Library databases before February 2023. Quality assessment was conducted using the Cochrane tool and Newcastle-Ottawa Quality Assessment Scale for Cohort Studies for randomized controlled trials (RCTs) and non-randomized trials, respectively. Objective response rate (ORR) and progression-free survival (PFS) at 3, 6, and 9 months were investigated as potential early efficacy endpoint candidates for 12-month overall survival (OS), with a strong correlation defined as Pearson's correlation coefficient r ≥ 0.8.

RESULTS

A total of 64 RCTs comprising 22,725 patients and 106 non-randomized prospective trials involving 10,608 participants were eligible for modeling and external validation, respectively. RCTs examined 15 different cancer types, predominantly non-small-cell lung cancer (NSCLC) (17, 28%), melanoma (9, 14%), and esophageal squamous cell carcinoma (5, 8%). The median sample size of RCTs was 124 patients, and the median follow-up time was 3.2-57.7 months. The ORR (r = 0.38; 95% confidence interval [CI], 0.18-0.54) and PFS (r = 0.42; 95% CI, 0.14-0.64) exhibited weak trial-level correlations with OS. Within ICI treatment arms, the r values of ORR and 3-, 6-, and 9-month PFS with 12-month OS were 0.61 (95% CI, 0.37-0.79), 0.78 (95% CI, 0.62-0.88), 0.84 (95% CI, 0.77-0.90), and 0.86 (95% CI, 0.79-0.90), respectively. External validation of 6-month PFS indicated an acceptable discrepancy between actual and predicted 12-month OS.

CONCLUSIONS

In non-randomized phase 2 trials on second-line or subsequent ICI therapy in patients with advanced solid cancers, 6-month PFS could serve as an early efficacy endpoint. However, early efficacy endpoints are not recommended in RCTs to replace OS.

Divide and Conquer-Targeted Therapy for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive and malignant type of breast cancer with limited treatment options and poor prognosis. One of the most significant impediments in TNBC treatment is the high heterogeneity of this disease, as highlighted by the detection of several molecular subtypes of TNBC. Each subtype is driven by distinct mutations and pathway aberrations, giving rise to specific molecular characteristics closely connected to clinical behavior, outcomes, and drug sensitivity. This review summarizes the knowledge regarding TNBC molecular subtypes and how it can be harnessed to devise tailored treatment strategies instead of blindly using targeted drugs. We provide an overview of novel targeted agents and key insights about new treatment modalities with an emphasis on the androgen receptor signaling pathway, cancer stem cell-associated pathways, phosphatidylinositol 3-kinase (PI3K)/AKT pathway, growth factor signaling, and immunotherapy.

Development of a prognostic model based on four genes related to exhausted CD8+ T cell in triple-negative breast cancer patients: a comprehensive analysis integrating scRNA-seq and bulk RNA-seq

Low immune infiltration is closely associated with poor clinical results and an unfavorable response to therapy in triple-negative breast cancer (TNBC). T-cell exhaustion (TEX) is a significant risk factor for tumor immunosuppression and invasion. Although improving TEX and enhancing effector function are promising strategies for strengthening immunotherapy, their role in the pathogenesis of TNBC remains unclear. This study's objective was to develop a prognostic model for TNBC based on exhausted CD8+ T-cell (CD8+ Tex)-related differentially expressed genes (DEGs) and to investigate its clinical and immune relevance. Initially, 398 CD8+ Tex-related genes were screened utilizing single-cell RNA sequencing (scRNA-seq) data from TNBC patients. Pseudotime analysis confirmed that CD8+ Tex mainly clustered at the end of the differentiation pathways, making them a critical subset in TNBC progression. By analyzing the TCGA cohort, ten CD8+ Tex-related DEGs were identified as significantly correlated with overall survival (OS) in TNBC patients, and a prognostic model containing four biomarkers (GBP1, CTSD, ABHD14B, and HLA-A) was constructed. The model demonstrated robust predictive capability in both the TCGA cohort and an external cohort, with the low-risk group exhibiting elevated expression of immunological checkpoint molecules and immune cell infiltration, as well as better responses to immunotherapy and chemotherapy. Furthermore, these four biomarkers were found to be highly expressed on CD8+ Tex and were associated with cellular communication efficiency. Therefore, this model is expected to be a new method for forecasting TNBC patients' prognosis and effectiveness of treatment, providing new insights for clinical decision-making.

The cardio-oncologic burden of breast cancer: molecular mechanisms and importance of preclinical models

Breast cancer, the most prevalent cancer affecting women worldwide, poses a significant cardio-oncological burden. Despite advancements in novel therapeutic strategies, anthracyclines, HER2 antagonists, and radiation remain the cornerstones of oncological treatment. However, each carries a risk of cardiotoxicity, though the molecular mechanisms underlying these adverse effects differ. Common mechanisms include DNA damage response, increased reactive oxygen species, and mitochondrial dysfunction, which are key areas of ongoing research for potential cardioprotective strategies. Since these mechanisms are also essential for effective tumor cytotoxicity, we explore tumor-specific effects, particularly in hereditary breast cancer linked to BRCA1 and BRCA2 mutations. These genetic variants impair DNA repair mechanisms, increase the risk of tumorigenesis and possibly for cardiotoxicity from treatments such as anthracyclines and HER2 antagonists. Novel therapies, including immune checkpoint inhibitors, are used in the clinic for triple-negative breast cancer and improve the oncological outcomes of breast cancer patients. This review discusses the molecular mechanisms underlying BRCA dysfunction and the associated pathological pathways. It gives an overview of preclinical models of breast cancer, such as genetically engineered mouse models, syngeneic murine models, humanized mouse models, and various in vitro and ex vivo systems and models to study cardiovascular side effects of breast cancer therapies. Understanding the underlying mechanism of cardiotoxicity and developing cardioprotective strategies in preclinical models are essential for improving treatment outcomes and reducing long-term cardiovascular risks in breast cancer patients.

Therapeutic strategies and landscape of metaplastic breast cancer

Metaplastic breast cancer is a rare and heterogeneous subtype of breast cancer, associated with a poor prognosis. Its distinct biological behavior and morphological features contribute to resistance to standard treatment regimens. Hitherto, the optimal therapeutic strategy for metaplastic breast cancer remains underexplored. Herein, we review the literature on the treatment of metaplastic breast cancer, summarizing current local and systemic therapies, and discuss potential therapeutic targets and novel strategies based on its pathological and molecular characteristics. Targeted therapy and immunotherapy may provide more personalized treatment options, with the potential to improve the prognosis of this disease.

Temporal and spatial composition of the tumor microenvironment predicts response to immune checkpoint inhibition

Immune checkpoint inhibition (ICI) has fundamentally changed cancer treatment. However, only a minority of patients with metastatic triple negative breast cancer (TNBC) benefit from ICI, and the determinants of response remain largely unknown. To better understand the factors influencing patient outcome, we assembled a longitudinal cohort with tissue from multiple timepoints, including primary tumor, pre-treatment metastatic tumor, and on-treatment metastatic tumor from 117 patients treated with ICI (nivolumab) in the phase II TONIC trial. We used highly multiplexed imaging to quantify the subcellular localization of 37 proteins in each tumor. To extract meaningful information from the imaging data, we developed SpaceCat, a computational pipeline that quantifies features from imaging data such as cell density, cell diversity, spatial structure, and functional marker expression. We applied SpaceCat to 678 images from 294 tumors, generating more than 800 distinct features per tumor. Spatial features were more predictive of patient outcome, including features like the degree of mixing between cancer and immune cells, the diversity of the neighboring immune cells surrounding cancer cells, and the degree of T cell infiltration at the tumor border. Non-spatial features, including the ratio between T cell subsets and cancer cells and PD-L1 levels on myeloid cells, were also associated with patient outcome. Surprisingly, we did not identify robust predictors of response in the primary tumors. In contrast, the metastatic tumors had numerous features which predicted response. Some of these features, such as the cellular diversity at the tumor border, were shared across timepoints, but many of the features, such as T cell infiltration at the tumor border, were predictive of response at only a single timepoint. We trained multivariate models on all of the features in the dataset, finding that we could accurately predict patient outcome from the pre-treatment metastatic tumors, with improved performance using the on-treatment tumors. We validated our findings in matched bulk RNA-seq data, finding the most informative features from the on-treatment samples. Our study highlights the importance of profiling sequential tumor biopsies to understand the evolution of the tumor microenvironment, elucidating the temporal and spatial dynamics underlying patient responses and underscoring the need for further research on the prognostic role of metastatic tissue and its utility in stratifying patients for ICI.

Tissue-resident immune cells: from defining characteristics to roles in diseases

Tissue-resident immune cells (TRICs) are a highly heterogeneous and plastic subpopulation of immune cells that reside in lymphoid or peripheral tissues without recirculation. These cells are endowed with notably distinct capabilities, setting them apart from their circulating leukocyte counterparts. Many studies demonstrate their complex roles in both health and disease, involving the regulation of homeostasis, protection, and destruction. The advancement of tissue-resolution technologies, such as single-cell sequencing and spatiotemporal omics, provides deeper insights into the cell morphology, characteristic markers, and dynamic transcriptional profiles of TRICs. Currently, the reported TRIC population includes tissue-resident T cells, tissue-resident memory B (BRM) cells, tissue-resident innate lymphocytes, tissue-resident macrophages, tissue-resident neutrophils (TRNs), and tissue-resident mast cells, but unignorably the existence of TRNs is controversial. Previous studies focus on one of them in specific tissues or diseases, however, the origins, developmental trajectories, and intercellular cross-talks of every TRIC type are not fully summarized. In addition, a systemic overview of TRICs in disease progression and the development of parallel therapeutic strategies is lacking. Here, we describe the development and function characteristics of all TRIC types and their major roles in health and diseases. We shed light on how to harness TRICs to offer new therapeutic targets and present burning questions in this field.

CD4+FOXP3Exon2+ regulatory T cell frequency predicts breast cancer prognosis and survival

CD4+FOXP3+ regulatory T cells (Tregs) suppress immune responses to tumors, and their accumulation in the tumor microenvironment (TME) correlates with poor clinical outcome in several cancers, including breast cancer (BC). However, the properties of intratumoral Tregs remain largely unknown. Here, we found that a functionally distinct subpopulation of Tregs, expressing the FOXP3 Exon2 splicing variants, is prominent in patients with hormone receptor-positive BC with poor prognosis. Notably, a comprehensive examination of the TCGA validated FOXP3E2 as an independent prognostic marker in all other BC subtypes. We found that FOXP3E2 expression underlies BCs with defective mismatch repair and a stem-like signature and highlights pathways involved in tumor survival. Last, we found that the TME induces FOXP3E2 through the CXCL12/CXCR4 axis and confirmed the higher immunosuppressive capacity of FOXP3E2+ Tregs derived from patients with BC. Our study suggests that FOXP3E2+ Tregs might be used as an independent biomarker to predict BC prognosis and survival and to develop super-targeted immunotherapies.

Injectable supramolecular hydrogel co-loading abemaciclib/NLG919 for neoadjuvant immunotherapy of triple-negative breast cancer

The efficacy of cancer immunotherapy relies on a sufficient amount of functional immune cells. Triple-negative breast cancer lacks enough immune cell infiltration, and adjuvant therapy is necessary to prime anti-tumor immunity. However, the improvement in efficacy is unsatisfactory with concern about inducing systemic immunotoxicity. Herein, we create an abemaciclib-loaded supramolecular peptide hydrogel formed by peptide-drug amphiphiles for neoadjuvant immunotherapy of triple-negative breast cancer, where the amphiphile is a conjugate of a β-sheet-forming peptide with 1-cyclohexyl-2-(5H-imidazo[5,1-a]isoindol-5-yl)ethanol (NLG919), an inhibitor of indoleamine 2,3-dioxygenase 1. The hydrogel can be injected into the tumor site and retained for at least one week for the sustained release of both abemaciclib and NLG919. The abemaciclib is able to induce immunogenic cell death of cancer cells and increase interleukin-2 secretion by cytotoxic T lymphocytes. Abemaciclib adversely upregulates indoleamine 2,3-dioxygenase 1, whose kynurenine production activity is inhibited by NLG919. The neoadjuvant immunotherapy reduces tumor recurrence and pulmonary metastasis and prolongs the survival of animals. This hydrogel provides a potential platform for neoadjuvant immunotherapy of triple-negative breast cancer with reduced toxicity compared with free abemaciclib.

PRAF2 as a novel biomarker for breast cancer with machine learning and experimentation validation

BACKGROUND

Breast cancer (BC) is the most prevalent malignancy in women. Potential therapeutic targets for BC are of great significance. In our previous study, we found that prenylated rab acceptor 1 domain family member 2 (PRAF2) is an oncogene in BC. However, the exact mechanism of PRAF2 in BC cancer promotion is still not fully understood.

METHODS

Pan-cancer analysis of PRAF2 was performed in the TIMER, Kaplan‒Meier, UALCAN and GEPIA databases.The prognostic value of PRAF2 in BC was investigated in the GEPIA database. The influence of PRAF2 on immune infiltration in BC was analyzed in the TISIDE and TIMER databases. Finally, we validated the expression of PRAF2 in our institutional samples. After downregulating PRAF2 in two BC cell lines, we tested cell proliferation by CCK-8 and Wound healing assays.

RESULTS

PRAF2 was highly expressed in various cancers, including BC, and in most BC cell lines. Higher expression of PRAF2 indicated poorer overall survival (OS) but not disease-free survival (DFS). Higher expression of PRAF2 is an independent prognostic factor in BC.PRAF2 is more highly expressed in BC than in the corresponding normal tissues. Downregulation of PRAF2 in BC can significantly inhibit viability and migration.

CONCLUSIONS

PRAF2 is highly expressed in various cancers, including BC. The expression of PRAF2 is related to Liquid-Liquid Phase Separation in BC. Finally, PRAF2 is upregulated in BC based on our institutional data. Downregulation of PRAF2 significantly inhibits cellular viability、migration in BC. PRAF2 may be a potential biomarker and therapeutic target for BC.

Insights into the Emerging Therapeutic Targets of Triple-negative Breast Cancer

Triple-negative Breast Cancer (TNBC), the most aggressive breast cancer subtype, is characterized by the non-appearance of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Clinically, TNBC is marked by its low survival rate, poor therapeutic outcomes, high aggressiveness, and lack of targeted therapies. Over the past few decades, many clinical trials have been ongoing for targeted therapies in TNBC. Although some classes, such as Poly (ADP Ribose) Polymerase (PARP) inhibitors and immunotherapies, have shown positive therapeutic outcomes, however, clinical effects are not much satisfiable. Moreover, the development of drug resistance is the major pattern observed in many targeted monotherapies. The heterogeneity of TNBC might be the cause for limited clinical benefits. Hence,, there is a need for the potential identification of new therapeutic targets to address the above limitations. In this context, some novel targets that can address the above-mentioned concerns are emerging in the era of TNBC therapy, which include Hypoxia Inducible Factor (HIF-1α), Matrix Metalloproteinase 9 (MMP-9), Tumour Necrosis Factor-α (TNF-α), β-Adrenergic Receptor (β-AR), Voltage Gated Sodium Channels (VGSCs), and Cell Cycle Regulators. Currently, we summarize the ongoing clinical trials and discuss the novel therapeutic targets in the management of TNBC.

Improving the efficacy of cancer immunotherapy by host-defence caerin 1.1 and 1.9 peptides

Cancer remains a major global health challenge. Immunotherapy has revolutionized the management of cancer, yet only a limited number of patients respond to such treatments. This is largely attributed to the immunosuppressive tumor microenvironment, which diminishes the effectiveness of immunotherapy. Recent studies have underscored the potential of naturally derived caerin 1 peptides, particularly caerin 1.1 and caerin 1.9, which exhibit strong antitumor effects and enhance the efficacy of immunotherapies in animal models. This review encapsulates the current research aimed at augmenting the effectiveness of immunotherapy, focusing on the role of caerin 1.1 and caerin 1.9 in boosting immunotherapeutic outcomes, elucidating possible mechanisms, and discussing their limitations and challenges.

Tumor microenvironment and immunotherapy for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a subtype of breast cancer known for its high aggressiveness and poor prognosis. Conventional treatment of TNBC is challenging due to its heterogeneity and lack of clear targets. Recent advancements in immunotherapy have shown promise in treating TNBC, with immune checkpoint therapy playing a significant role in comprehensive treatment plans. The tumor microenvironment (TME), comprising immune cells, stromal cells, and various cytokines, plays a crucial role in TNBC progression and response to immunotherapy. The high presence of tumor-infiltrating lymphocytes and immune checkpoint proteins in TNBC indicates the potential of immunotherapeutic strategies. However, the complexity of the TME, while offering therapeutic targets, requires further exploration of its multiple roles in immunotherapy. In this review, we discuss the interaction mechanism between TME and TNBC immunotherapy based on the characteristics and composition of TME, and elaborate on and analyze the effect of TME on immunotherapy, the potential of TME as an immune target, and the ability of TME as a biomarker. Understanding these dynamics will offer new insights for enhancing therapeutic approaches and investigating stratification and prognostic markers for TNBC patients.

Knowledge mapping of immunotherapy for breast cancer: A bibliometric analysis from 2013 to 2022

Breast cancer is the leading cause of cancer-related death among women globally. Immunotherapy has emerged as a major milestone in contemporary oncology. This study aims to conduct a bibliometric analysis in the field of immunotherapy for breast cancer, providing a comprehensive overview of the current research status, identifying trends and hotspots in research topics. We searched and retrieved data from the Web of Science Core Collection, and performed a bibliometric analysis of publications on immunotherapy for breast cancer from 2013 to 2022. Current status and hotspots were evaluated by co-occurrence analysis using VOSviewer. Evolution and bursts of knowledge base were assessed by co-citation analysis using CiteSpace. Thematic evolution by bibliometrix package was used to discover keywords trends. The attribution and collaboration of countries/regions, institutions and authors were also explored. A total of 7,975 publications were included. In co-occurrence analysis of keywords, 6 major clusters were revealed: tumor microenvironment, prognosis biomarker, immune checkpoints, novel drug delivery methods, immune cells and therapeutic approaches. The top three most frequently mentioned keywords were tumor microenvironment, triple-negative breast cancer, and programmed cell death ligand 1. The most productive country, institution and author were the USA (2926 publications), the University of Texas MD Anderson Cancer Center (219 publications), and Sherene Loi (28 publications), respectively. There has been a rapid growth in studies on immunotherapy for breast cancer worldwide. This research area has gained increasing attention from different countries and institutions. With the rising incidence of breast cancer, immunotherapy represents a research field of significant clinical value and potential.

Current and future immunotherapy for breast cancer

Substantial therapeutic advancement has been made in the field of immunotherapy in breast cancer. The immune checkpoint inhibitor pembrolizumab in combination with chemotherapy received FDA approval for both PD-L1 positive metastatic and early-stage triple-negative breast cancer, while ongoing clinical trials seek to expand the current treatment landscape for immune checkpoint inhibitors in hormone receptor positive and HER2 positive breast cancer. Antibody drug conjugates are FDA approved for triple negative and HER2+ disease, and are being studied in combination with immune checkpoint inhibitors. Vaccines and bispecific antibodies are areas of active research. Studies of cellular therapies such as tumor infiltrating lymphocytes, chimeric antigen receptor-T cells and T cell receptor engineered cells are promising and ongoing. This review provides an update of recent major clinical trials of immunotherapy in breast cancer and discusses future directions in the treatment of breast cancer.

Novel Molecular Classification of Breast Cancer with PET Imaging

Breast cancer is a heterogeneous disease characterized by a wide range of biomarker expressions, resulting in varied progression, behavior, and prognosis. While traditional biopsy-based molecular classification is the gold standard, it is invasive and limited in capturing tumor heterogeneity, especially in deep or metastatic lesions. Molecular imaging, particularly positron emission tomography (PET) imaging, offering a non-invasive alternative, potentially plays a crucial role in the classification and management of breast cancer by providing detailed information about tumor location, heterogeneity, and progression. This narrative review, which focuses on both clinical patients and preclinical studies, explores the latest advancements in PET imaging for breast cancer, emphasizing the development of new tracers targeting hormone receptors such as the estrogen alpha receptor, progesterone receptor, androgen receptor, estrogen beta receptor, as well as the ErbB family of receptors, VEGF/VEGFR, PARP1, PD-L1, and markers for indirectly assessing Ki-67. These innovative radiopharmaceuticals have the potential to guide personalized treatment approaches based on the unique tumor profiles of individual patients. Additionally, they may improve the assessment of treatment efficacy, ultimately leading to better outcomes for those diagnosed with breast cancer.

Identifying subgroups deriving the most benefit from PD-1 checkpoint inhibition plus chemotherapy in advanced metastatic triple-negative breast cancer: a systematic review and meta-analysis

BACKGROUND

The combination of immunotherapy and chemotherapy has demonstrated an enhancement in progression-free survival (PFS) for individuals with advanced and metastatic triple-negative breast cancer (TNBC) when compared to the use of chemotherapy alone. Nevertheless, the extent to which different subgroups of metastatic TNBC patients experience this benefit remains uncertain.

OBJECTIVES

Our objective was to conduct subgroup analyses to more precisely identify the factors influencing these outcomes.

MATERIALS AND METHODS

The PubMed database was searched until Dec 2023 for studies that compared PD-1 checkpoint inhibitors plus chemotherapy (ICT) with chemotherapy (CT) alone. The primary outcome of interest was progression-free survival (PFS). Review Manager (RevMan) version 5.4. was used for the data analysis.

RESULTS

Four randomized controlled trials (RCTs) comprising 2468 advanced and metastatic TNBC were included in this systematic review and meta-analysis. PFS surge with combined therapy was observed in White (HR 0.80 [0.70, 0.91], p = 0.0007) and Asian ethnicities (HR 0.73 [0.58, 0.93], p = 0.01) but not in Blacks (HR 0.72 [0.42, 1.24], p = 0.24). Overall, patients with distant metastasis demonstrated to derive the PFS benefit from additional immunotherapy (HR 0.87 [0.77, 0.99], p = 0.03); however, metastasis to individual distant site was associated with failure to achieve any treatment difference (Bone: HR 0.79 [0.41, 1.52], p = 0.49; Lung: HR 0.85 [0.70, 1.04], p = 0.11; Liver: HR 0.80 [0.64, 1.01], p = 0.06). While number of metastases > 3 also showed to impact the PFS advantage (HR 0.89 [0.69, 1.16], p = 0.39). While patients, regardless of prior chemotherapy, experienced a notable enhancement in PFS with ICT (Overall: HR 0.79 [0.71, 0.88], p < 0.0001; Yes: HR 0.87 [0.76, 1.00], p = 0.05; No: HR 0.67 [0.56, 0.80], p < 0.00001), those previously exposed to chemotherapy exhibited a significantly smaller PFS advantage compared to those without prior chemotherapy, as evidenced by a significant subgroup difference (Test for subgroup difference: P = 0.02, I2 = 82.2%). Patients lacking PD-L1 expression also failed to achieve any additional benefit from immunotherapy (PD-L1-: HR 0.95 [0.81, 1.12]; p = 0.54; PD-L1+: HR 0.73 [0.64, 0.85], p < 0.0001). Age, ECOG status, and presentation with de novo metastasis/recurrent shown no impact on IT-associated PFS advantage.

CONCLUSIONS

Patient- and treatment- related factors such as ethnicity, distant metastases, number of metastases (> 3), previous exposure to chemotherapy and PD-L1 expression, seem to influence or restrict the advantage in progression-free survival associated with the addition of immunotherapy to chemotherapy, as opposed to chemotherapy alone, in patients with advanced and metastatic TNBC. Larger studies are warranted to validate these outcomes.

Recent advancements in biomarkers and molecular diagnostics in hormonal receptor-positive breast cancer

Molecular applications have limited use in breast cancer compared to other cancer types. In recent years, with an improving appreciation of the molecular genetics of breast cancer and innovative novel targeted and immune-mediated therapeutics, opportunities have arisen for more biomarker analysis and molecular applications in the diagnosis and treatment of both locally advanced and metastatic breast cancers. In hormone receptor-positive, HER2-negative breast cancers, a growing number of revolutionized personalized therapies are in clinical use or on trials, such as CDK4/6 inhibitors and immune checkpoint inhibitors in adjuvant and neoadjuvant settings, and PIK3CA inhibitors in metastatic disease. In this review, we focus on biomarkers associated with those new therapeutic targets and molecular applications for genetic alterations associated with drug resistance or interaction from a pathology perspective for selecting and optimizing breast cancer treatment.

Patterns of immune evasion in triple-negative breast cancer and new potential therapeutic targets: a review

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by the absence of progesterone and estrogen receptors and low (or absent) HER2 expression. TNBC accounts for 15-20% of all breast cancers. It is associated with younger age, a higher mutational burden, and an increased risk of recurrence and mortality. Standard treatment for TNBC primarily relies on cytotoxic agents, such as taxanes, anthracyclines, and platinum compounds for both early and advanced stages of the disease. Several targeted therapies, including bevacizumab and sunitinib, have failed to demonstrate significant clinical benefit in TNBC. The emergence of immune checkpoint inhibitors (ICI) has revolutionized cancer treatment. By stimulating the immune system, ICIs induce a durable anti-tumor response across various solid tumors. TNBC is a particularly promising target for treatment with ICIs due to the higher levels of tumor-infiltrating lymphocytes (TIL), increased PD-L1 expression, and higher mutational burden, which generates tumor-specific neoantigens that activate immune cells. ICIs administered as monotherapy in advanced TNBC yields only a modest response; however, response rates significantly improve when ICIs are combined with cytotoxic agents, particularly in tumors expressing PD-L1. Pembrolizumab is approved for use in both early and advanced TNBC in combination with standard chemotherapy. However, more research is needed to identify more potent biomarkers, and to better elucidate the synergism of ICIs with other targeted agents. In this review, we explore the challenges of immunotherapy in TNBC, examining the mechanisms of tumor progression mediated by immune cells within the tumor microenvironment, and the signaling pathways involved in both primary and acquired resistance. Finally, we provide a comprehensive overview of ongoing clinical trials underway to investigate novel immune-targeted therapies for TNBC.

Prognostic value of tumor-infiltrating lymphocyte subtypes and microorganisms in triple-negative breast cancer

ABSTRACT

Tumor-infiltrating lymphocytes (TILs) are key components of the tumor microenvironment (TME) and serve as prognostic markers for breast cancer. Patients with high TIL infiltration generally experience better clinical outcomes and extended survival compared to those with low TIL infiltration. However, as the TME is highly complex and TIL subtypes perform distinct biological functions, TILs may only provide an approximate indication of tumor immune status, potentially leading to biased prognostic results. Therefore, we reviewed the interactions between immune-infiltrating subtypes and tumor cells throughout the entire TME. By examining the antitumor or protumor effects of each TIL subtype, we aimed to better characterize the tumor immune landscape, offering more accurate and comprehensive insights for guiding triple-negative breast cancer (TNBC) treatment. In addition, this approach could lead to the development of new therapeutic targets, enabling tailored treatment strategies and precision medicine. Accumulating evidence suggests that the intestinal microbiome and its metabolites influence antitumor responses by modulating innate and adaptive immunity, with specific bacteria potentially serving as biomarkers for predicting clinical responses. Various studies have identified microorganisms in breast tissue, previously considered sterile, revealing differences in breast microbial composition between patients with breast cancer and controls, as well as associations between specific breast microorganisms and clinicopathologic features, including immune correlations. The aim of this review was to provide a more comprehensive set of prognostic markers for TNBC and to tap into potential-specific therapeutic targets.

Efficacy and safety of PARPis combined with an ICIs for advanced or metastatic triple-negative breast cancer: a single-arm meta-analysis

Although the intervention for triple-negative breast cancer (TNBC) patients has improved and survival time has increased, the combination of immune checkpoint inhibitors(ICIs) and PARP inhibitors (Poly ADP-Ribose Polymerase inhibitors, PARPis) is still controversial. Previous studies revealed that the combined use of ICIs and PARPis led to increased antitumor activity. However, most of these combined regimens are nonrandomized controlled trials with small sample sizes. The purpose of this meta-analysis was to evaluate the efficacy and safety of ICIs combined with PARPis in patients with advanced or metastatic TNBC. The PubMed, Embase, Cochrane Library and Web of Science databases were systematically searched. The results including the objective remission rate (ORR), disease control rate (DCR), progression-free survival (PFS) and adverse events (AEs), were subjected to further analysis. Four studies involving 110 subjects were included in this meta-analysis. The combined ORR and DCR were 23.6% and 53.6%, respectively; while the ORR and DCR of BRCAmut patients were 38.1% and 71.4%, respectively. The median PFS of the patients was 4.29 months. As for safety, the most common AEs were nausea (49.0%), anemia (44.3%) and fatigue (40.6%). Most of them were grade 1 or 2, and the incidence of adverse events ≥ III was obviously low. Except for anemia, the incidence of AEs ≥ III was < 10%. This meta-analysis revealed that the combination of ICIs and PARPis has good efficacy and safety for advanced or metastatic TNBC patients.

Virtual patient analysis identifies strategies to improve the performance of predictive biomarkers for PD-1 blockade

Patients with metastatic triple-negative breast cancer (TNBC) show variable responses to PD-1 inhibition. Efficient patient selection by predictive biomarkers would be desirable but is hindered by the limited performance of existing biomarkers. Here, we leveraged in silico patient cohorts generated using a quantitative systems pharmacology model of metastatic TNBC, informed by transcriptomic and clinical data, to explore potential ways to improve patient selection. We evaluated and quantified the performance of 90 biomarker candidates, including various cellular and molecular species, at different cutoffs by a cutoff-based biomarker testing algorithm combined with machine learning-based feature selection. Combinations of pretreatment biomarkers improved the specificity compared to single biomarkers at the cost of reduced sensitivity. On the other hand, early on-treatment biomarkers, such as the relative change in tumor diameter from baseline measured at two weeks after treatment initiation, achieved remarkably higher sensitivity and specificity. Further, blood-based biomarkers had a comparable ability to tumor- or lymph node-based biomarkers in identifying a subset of responders, potentially suggesting a less invasive way for patient selection.