CTLA-4 Expression and Its Clinical Significance in Breast Cancer

Exploring the Immunological Profile in Breast Cancer: Recent Advances in Diagnosis and Prognosis through Circulating Tumor Cells

This review offers a comprehensive exploration of the intricate immunological landscape of breast cancer (BC), focusing on recent advances in diagnosis and prognosis through the analysis of circulating tumor cells (CTCs). Positioned within the broader context of BC research, it underscores the pivotal role of the immune system in shaping the disease's progression. The primary objective of this investigation is to synthesize current knowledge on the immunological aspects of BC, with a particular emphasis on the diagnostic and prognostic potential offered by CTCs. This review adopts a thorough examination of the relevant literature, incorporating recent breakthroughs in the field. The methodology section succinctly outlines the approach, with a specific focus on CTC analysis and its implications for BC diagnosis and prognosis. Through this review, insights into the dynamic interplay between the immune system and BC are highlighted, with a specific emphasis on the role of CTCs in advancing diagnostic methodologies and refining prognostic assessments. Furthermore, this review presents objective and substantiated results, contributing to a deeper understanding of the immunological complexity in BC. In conclusion, this investigation underscores the significance of exploring the immunological profile of BC patients, providing valuable insights into novel advances in diagnosis and prognosis through the utilization of CTCs. The objective presentation of findings emphasizes the crucial role of the immune system in BC dynamics, thereby opening avenues for enhanced clinical management strategies.

Relationship between immune checkpoint proteins and neoadjuvant chemotherapy response in breast cancer

INTRODUCTION

Following major developments in cancer immunotherapy, treatments targeting immune checkpoint proteins (ICP) gained interest in breast cancer, though studies mostly focus on patients with metastatic disease as well as patients nonresponsive to the conventional treatments. Herein, we aimed to investigate the levels of ICP in tumor stroma and tumor infiltrating lymphocytes, and tumor tissue prior to neoadjuvant chemotherapy administration to evaluate the relationship between ICP levels, clinicopathological parameters, and NAC response.

MATERIALS AND METHODS

This study was conducted with 51 patients where PD-1, PD-L1, CTLA-4, TIM-3, CD24 and CD44 levels were investigated in CD45+ cells while CD326, CD24, CD44 and PD-L1 protein expression levels were investigated in CD45- population. In addition, CD44 and CD24 levels were evaluated in the tumor stroma. TIL levels were investigated according to the TILS Working Group. Treatment responses after NAC were evaluated according to the MD Anderson RCB score.

RESULTS

Our results revealed positive correlation between CTLA-4 and CD44 expression in cases with high TIL levels as well as TIL levels and CTLA-4 expression in cases with partial response. Similarly, positive correlation was detected between TIM3 and PD-L1 levels in cases with good response. In addition, a negative correlation between TILs after NAC and PD-1/PD-L1 expression in lymphocytes in cases with partial complete response.

CONCLUSIONS

Our study provides preliminary data about the correlation between ICP and clinicopathological status and NAC response in breast cancer, in addition to underlining the requirement for further research to determine their potential as therapeutic targets.

Addition of immune checkpoint inhibitors to chemotherapy versus chemotherapy alone in patients with triple-negative breast cancer: A systematic review and meta-analysis

BACKGROUND

Triple-negative breast cancer (TNBC) is a relatively common malignant tumor with high mortality rates. There are limited treatment options and current therapy regimens often fall short of providing positive outcomes. The development of immune checkpoint inhibitors (ICIs) have provided a vital treatment option although efficacy has varied. Here, we review patient response to current TNBC treatment with and without the addition of ICIs.

METHODS

A systematic search of PubMed, Cochrane, and EMBASE library databases was done to search eligible studies published from their inception through April 3, 2022. The primary outcome indicators used were progression-free survival (PFS), overall survival (OS), pathological complete response rate (pCR) and objective remission rate (ORR), while adverse events (AEs) were also analyzed. Publication bias and sensitivity analyses and were performed to evaluate the quality of assessment.

RESULTS

Overall, the meta-analysis looked at seven randomized controlled trials (RCTs) that included 4631 patients with TNBC. Results showed an improvement in PFS for patients receiving ICI in addition to chemotherapy (CT) in both the intent-to-treat (ITT) population and PD-L1 positive patients. Increased pCR rates were observed in all patients irrespective of PD-L1 status as well as increased ORR in the ITT which was more notable in PD-L1 positive subjects. While significant improvement in OS was observed only in PD-L1 positive individuals, the use of ICIs plus CT resulted in severe adverse reactions, specifically immune-related.

CONCLUSIONS

This study supports the increased efficacy of ICIs in combination with CT compared to CT alone in patients with TNBC, with the most notable benefit observed in PD-L1 positive patients. However, combination therapy increases the risk of adverse reactions which warrants further investigation.

Molecular and serological biomarkers to predict trastuzumab responsiveness in HER-2 positive breast cancer

HER-2-positive breast cancer is characterized by its aggressive nature, poor prognosis, and reduced overall survival. The emergence of trastuzumab resistance is currently considered a global problem. The immune system plays a pivotal role in tumor progression and development. Cytotoxic T lymphocyte-associated protein-4 (CTLA-4) and other immune checkpoint proteins may be potential prognostic factors and therapeutic targets for breast cancer. This study aimed to determine the correlation between CTLA-4 expression in peripheral blood and insulin-like growth factor-1 (IGF-1) serum levels and their impact on trastuzumab responsiveness in HER-2-positive patients with breast cancer. CTLA-4 expression was analyzed in peripheral blood cells using quantitative PCR, while IGF-1 serum levels were assessed through electrochemiluminescence assays. There was a significant increase in CTLA-4 expression at cycle 9, which continued to increase until it reached 4.6 at cycle 17. High IGF-1 levels were observed in newly diagnosed HER-2 positive patients before trastuzumab therapy, significantly decreasing post-therapy (p=0.001). Co-targeting HER-2 and IGF-1 receptors may reduce the risk of recurrence and improve outcomes. In addition, targeted CTLA-4 molecules may improve patient survival and prevent recurrence.

Unveiling the Immune Microenvironment's Role in Breast Cancer: A Glimpse into Promising Frontiers

Breast cancer (BC), one of the most widespread and devastating diseases affecting women worldwide, presents a significant public health challenge. This review explores the emerging frontiers of research focused on deciphering the intricate interplay between BC cells and the immune microenvironment. Understanding the role of the immune system in BC is critical as it holds promise for novel therapeutic approaches and precision medicine strategies. This review delves into the current literature regarding the immune microenvironment's contribution to BC initiation, progression, and metastasis. It examines the complex mechanisms by which BC cells interact with various immune cell populations, including tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs). Furthermore, this review highlights the impact of immune-related factors, such as cytokines and immune checkpoint molecules. Additionally, this comprehensive analysis sheds light on the potential biomarkers associated with the immune response in BC, enabling early diagnosis and prognostic assessment. The therapeutic implications of targeting the immune microenvironment are also explored, encompassing immunotherapeutic strategies and combination therapies to enhance treatment efficacy. The significance of this review lies in its potential to pave the way for novel therapeutic interventions, providing clinicians and researchers with essential knowledge to design targeted and personalized treatment regimens for BC patients.

The Expression of CTLA-4 in Breast Tumors and Tumor-Infiltrating Leukocytes Affects Patients' Systemic Inflammatory Status and Varies According to Their Molecular Subtypes

Recent evidence has pointed out that the cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) expression is a poor prognosis factor. However, the implications of CTLA-4 expression on circulating inflammatory mediators are unclear for breast cancer. Tumor biopsies and blood samples were collected from 117 breast cancer patients. Oxidative stress parameters were evaluated in plasma samples by measuring the lipoperoxidation profile and nitric oxide metabolites (NOx). Interleukins 12 (IL-12) and 4 (IL-4) were assessed by ELISA. CTLA-4 expression was determined by immunofluorescence assessed by its labeling in tumor-infiltrating leukocytes (TILs) or breast tumors. Correlations between CTLA-4 expression in breast tumors with TCD4/TCD8 infiltrating lymphocyte and inflammation-related genes were performed using data from TIMER 2.0/TCGA databases (n = 2160). CTLA-4 expression in TILs significantly correlated to triple-negative breast tumors. Patients carrying CTLA-4-positive tumors exhibited lower plasmatic NOx levels, and those expressing CTLA-4 in TILs had reduced levels of IL-12 in plasma. No changes in either IL-4 or lipid peroxidation profiles were detected concerning any CTLA4 status. Compared to the Luminal A ones, oxidative stress parameters and cytokines were observed in patients bearing triple-negative tumors. CTLA-4 expression in all breast cancer subtypes positively correlated to TCD4/TCD8 lymphocyte infiltrates, as well as to the pro-inflammatory genes IL12A, IL4, NFKB1, NFKB2, NOS1, NOS2, and NOS3. CTLA-4 expression in both tumor and TILs can affect the systemic inflammatory status of breast cancer patients, especially antitumor molecules such as IL-12 and NOx that correlate to more aggressive disease.

Herpesvirus entry mediator as a potential biomarker in breast cancer compared with conventional cytotoxic T‑lymphocyte‑associated antigen 4

Breast cancer (BC) is the most common cancer in women worldwide, with 2.3 million cases recorded in 2020. Despite improvements in cancer treatment, patients with BC still succumb to the disease, due to regional and distant metastases when diagnosed at later stages. Several immune checkpoint inhibitors have been approved for BC treatment, based on their expression and role in maintaining immunosurveillance against tumors. The present study aimed to evaluate the expression of 12 immune checkpoints in patients with BC, and assess their role as diagnostic and therapeutic markers. Expression levels were measured using reverse transcription-quantitative polymerase chain reaction. Among the 12 immune markers, herpesvirus entry mediator (HVEM) was found to be significantly upregulated in patients with malignant BC compared to non-malignant controls, with a relative fold change (FC) of 1.46 and P=0.012. A similar finding was observed for cytotoxic T-lymphocyte-associated antigen 4 (CTLA4; FC=1.47 and P=0.035). In addition, receiver operating characteristic curve analysis revealed that HVEM expression allowed significant differentiation between groups, with an area under the curve of 0.74 (P=0.013). Upregulation in both HVEM and CTLA4 was revealed to be significantly associated with the human epidermal growth factor receptor-2 (HER2)-enriched phenotype (FC=3.53, P=0.009 and FC=5.98, P=0.002, respectively), while only HVEM was significantly associated with the triple-negative phenotype (FC=2.07, P=0.016). Furthermore, HVEM was significantly higher in patients with grade III tumors (FC=1.88, P=0.025) and negative vascular invasion (FC=1.67, P=0.046) compared with non-malignant controls. Serum protein levels were assessed by multiplex immunoassay, and a significant increase in HVEM was detected in patients with malignant BC compared with that in non-malignant controls (P=0.035). These data indicated that HVEM may serve as a potential biomarker and target for immunotherapy, especially for certain types of BC.

Identification of PIMREG as a novel prognostic signature in breast cancer via integrated bioinformatics analysis and experimental validation

Background

Phosphatidylinositol binding clathrin assembly protein interacting mitotic regulator (PIMREG) expression is upregulated in a variety of cancers. However, its potential role in breast cancer (BC) remains uncertain.

Methods

The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were used to gather relevant information. The expression of PIMREG and its clinical implication in BC were assessed by using Wilcoxon rank-sum test. The prognostic value of PIMREG in BC was evaluated through the Cox regression model and nomogram, and visualized by Kaplan-Meier survival curves. Genes/proteins that interact with PIMREG in BC were also identified through GeneMANIA and MaxLink. Gene set enrichment analysis (GSEA) was then performed. The correlations of the immune cell infiltration and immune checkpoints with the expression of PIMREG in BC were explored via TIMER, TISIDB, and GEPIA. Potential drugs that interact with PIMREG in BC were explored via Q-omic. The siRNA transfection, CCK-8, and transwell migration assay were conducted to explore the function of PIMREG in cell proliferation and migration.

Results

PIMREG expression was significantly higher in infiltrating ductal carcinoma, estrogen receptor negative BC, and progestin receptor negative BC. High expression of PIMREG was associated with poor overall survival, disease-specific survival, and progression-free interval. A nomogram based on PIMREG was developed with a satisfactory prognostic value. PIMREG also had a high diagnostic ability, with an area under the curve of 0.940. Its correlations with several immunomodulators were also observed. Immune checkpoint CTLA-4 was significantly positively associated with PIMREG. HDAC2 was found as a potentially critical link between PIMREG and BRCA1/2. In addition, PIMREG knockdown could inhibit cell proliferation and migration in BC.

Conclusions

The high expression of PIMREG is associated with poor prognosis and immune checkpoints in BC. HDAC2 may be a critical link between PIMREG and BRCA1/2, potentially a therapeutic target.

Establishment of cancer-associated fibroblasts-related subtypes and prognostic index for prostate cancer through single-cell and bulk RNA transcriptome

Current evidence indicate that cancer-associated fibroblasts (CAFs) play an important role in prostate cancer (PCa) development and progression. In this study, we identified CAF-related molecular subtypes and prognostic index for PCa patients undergoing radical prostatectomy through integrating single-cell and bulk RNA sequencing data. We completed analyses using software R 3.6.3 and its suitable packages. Through single-cell and bulk RNA sequencing analysis, NDRG2, TSPAN1, PTN, APOE, OR51E2, P4HB, STEAP1 and ABCC4 were used to construct molecular subtypes and CAF-related gene prognostic index (CRGPI). These genes could clearly divide the PCa patients into two subtypes in TCGA database and the BCR risk of subtype 1 was 13.27 times higher than that of subtype 2 with statistical significance. Similar results were observed in MSKCC2010 and GSE46602 cohorts. In addtion, the molucular subtypes were the independent risk factor of PCa patients. We orchestrated CRGPI based on the above genes and divided 430 PCa patients in TCGA database into high- and low- risk groups according to the median value of this score. We found that high-risk group had significant higher risk of BCR than low-risk group (HR: 5.45). For functional analysis, protein secretion was highly enriched in subtype 2 while snare interactions in vesicular transport was highly enriched in subtype 1. In terms of tumor heterogeneity and stemness, subtype 1 showd higher levels of TMB than subtype 2. In addition, subtype 1 had significant higher activated dendritic cell score than subtype 2. Based on eight CAF-related genes, we developed two prognostic subtypes and constructed a gene prognostic index, which could predict the prognosis of PCa patients very well.

Membrane tension-mediated stiff and soft tumor subtypes closely associated with prognosis for prostate cancer patients

BACKGROUND

Prostate cancer (PCa) is usually considered as cold tumor. Malignancy is associated with cell mechanic changes that contribute to extensive cell deformation required for metastatic dissemination. Thus, we established stiff and soft tumor subtypes for PCa patients from perspective of membrane tension.

METHODS

Nonnegative matrix factorization algorithm was used to identify molecular subtypes. We completed analyses using software R 3.6.3 and its suitable packages.

RESULTS

We constructed stiff and soft tumor subtypes using eight membrane tension-related genes through lasso regression and nonnegative matrix factorization analyses. We found that patients in stiff subtype were more prone to biochemical recurrence than those in soft subtype (HR 16.18; p < 0.001), which was externally validated in other three cohorts. The top ten mutation genes between stiff and soft subtypes were DNAH, NYNRIN, PTCHD4, WNK1, ARFGEF1, HRAS, ARHGEF2, MYOM1, ITGB6 and CPS1. E2F targets, base excision repair and notch signaling pathway were highly enriched in stiff subtype. Stiff subtype had significantly higher TMB and T cells follicular helper levels than soft subtype, as well as CTLA4, CD276, CD47 and TNFRSF25.

CONCLUSIONS

From the perspective of cell membrane tension, we found that stiff and soft tumor subtypes were closely associated with BCR-free survival for PCa patients, which might be important for the future research in the field of PCa.

Impact of [18F]FDG PET/CT in the Assessment of Immunotherapy-Induced Arterial Wall Inflammation in Melanoma Patients Receiving Immune Checkpoint Inhibitors

We aimed to investigate the role of [¹⁸F]FDG positron emission tomography/computed tomography (PET/CT) in the early detection of arterial wall inflammation (AWI) in melanoma patients receiving immune checkpoint inhibitors (ICIs). Our retrospective study enrolled 95 melanoma patients who had received ICIs. Inclusion criteria were ICI therapy for at least six months and at least three [¹⁸F]FDG PET/CTs, including one pretreatment session plus two scans three and six months after treatment initiation. AWI was assessed using quantitative and qualitative methods in the subclavian artery, thoracic aorta, and abdominal aorta. We found three patients with AWI visual suspicion in the baseline scan, which increased to five in the second and twelve in the third session. Most of these patients' treatments were terminated due to either immune-related adverse events (irAEs) or disease progression. In the overall population, the ratio of arterial-wall maximum standardized uptake value (SUVmax)/liver-SUVmax was significantly higher three months after treatment than the pretreatment scan in the thoracic aorta (0.83 ± 0.12 vs. 0.79 ± 0.10; p-value = 0.01) and subclavian artery (0.67 ± 0.13 vs. 0.63 ± 0.12; p-value = 0.01), and it remained steady in the six-month follow-up. None of our patients were diagnosed with definite clinical vasculitis on the dermatology follow-up reports. To conclude, our study showed [¹⁸F]FDG PET/CT's potential to visualise immunotherapy-induced subclinical inflammation in large vessels. This may lead to more accurate prediction of irAEs and better patient management.

Immune Checkpoint and EMT-Related Molecules in Circulating Tumor Cells (CTCs) from Triple Negative Breast Cancer Patients and Their Clinical Impact

Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype. There are few targeted therapies for these patients, leading to an unmet need for new biomarkers. The present study aimed to investigate the expression of PD-L1, CTLA-4, GLU, and VIM in CTCs of TNBC patients. Ninety-five patients were enrolled in this study: sixty-four TNBC and thirty-one luminal. Of these patients, 60 were in the early stage, while 35 had metastatic disease. Protein expression was identified by immunofluorescence staining experiments and VyCAP analysis. All the examined proteins were upregulated in TNBC patients. The expression of the GLU+VIM+CK+ phenotype was higher (50%) in metastatic TNBC compared to early TNBC patients (17%) (p = 0.005). Among all the BC patients, a significant correlation was found between PD-L1+CD45-CK+ and CTLA-4+CD45-CK+ phenotypes (Spearman test, p = 0.024), implying an important role of dual inhibition in BC. Finally, the phenotypes GLU+VIM+CK+ and PD-L1+CD45-CK+ were associated with shorter OS in TNBC patients (OS: log-rank p = 0.048, HR = 2.9, OS: log-rank p < 0.001, HR = 8.7, respectively). Thus, PD-L1, CTLA-4, GLU, and VIM constitute significant biomarkers in TNBC associated with patients' outcome, providing new therapeutic targets for this difficult breast cancer subtype.

Occupational Exposure to Pesticides Affects Pivotal Immunologic Anti-Tumor Responses in Breast Cancer Women from the Intermediate Risk of Recurrence and Death

Simple Summary

This study presents information regarding the immunological changes induced by pesticide exposure in patients diagnosed with breast cancer occupationally exposed to pesticides. Such changes are helpful to understand tumor behavior under pesticide exposure and can be beneficial to re-stratify breast cancer patients occupationally exposed concerning their risk of disease recurrence and death.

Abstract

Breast cancer risk stratification is a strategy based using on clinical parameters to predict patients’ risk of recurrence or death, categorized as low, intermediate, or high risk. Both low and high risk are based on well-defined clinical parameters. However, the intermediate risk depends on more malleable parameters. It means an increased possibility for either suboptimal treatment, leading to disease recurrence, or systemic damage due to drug overload toxicity. Therefore, identifying new factors that help to characterize better the intermediate-risk stratification, such as environmental exposures, is necessary. For this purpose, we evaluated the impact of occupational exposure to pesticides on the systemic profile of cytokines (IL-12, IL-4, IL-17A, and TNF-α) and oxidative stress (hydroperoxides, total antioxidants, and nitric oxide metabolites), as well as TGF-β1, CTLA-4, CD8, and CD4 expression, investigated in tumor cells. Occupational exposure to pesticides decreased the levels of IL-12 and significantly increased the expression of TGF-β1 and CTLA-4 in the immune infiltrate. Nevertheless, we observed a decrease in CTLA-4 in tumor samples and CD8 in infiltrating cells of intermediate overweight or obese patients with at least one metastatic lymph node at the diagnosis. These findings indicate that occupational exposure to pesticides changes the molecular behavior of disease and should be considered for intermediate-risk stratification assessment in breast cancer patients.

A novel lactate metabolism-related signature predicts prognosis and tumor immune microenvironment of breast cancer

Background: Lactate, an intermediate product of glycolysis, has become an essential regulator of tumor maintenance, development, and metastasis. Lactate can drive tumors by changing the microenvironment of tumor cells. Because of lactate’s important role in cancer, we aim to find a novel prognostic signature based on lactate metabolism-related genes (LMRGs) of breast cancer (BC).

Methods: RNA-sequencing data and clinical information of BC were enrolled from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. We obtained LMRGs from the Molecular Signature Database v7.4 and articles, and then we compared candidate genes with TCGA data to get differential genes. Univariate analysis and most minor absolute shrinkage and selector operator (LASSO) Cox regression were employed to filter prognostic genes. A novel lactate metabolism-related risk signature was constructed using a multivariate Cox regression analysis. The signature was validated by time-dependent ROC curve analyses and Kaplan–Meier analyses in TCGA and GEO cohorts. Then, we further investigated in depth the function of the model’s immune microenvironment.

Results: We constructed a 3-LMRG-based risk signature. Kaplan–Meier curves confirmed that high-risk score subgroups had a worse prognosis in TCGA and GEO cohorts. Then a nomogram to predict the probability of survival for BC was constructed. We also performed Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway function analysis. The function analysis showed that the lactate metabolism-related signature was significantly related to immune response. A significant correlation was observed between prognostic LMRGs and tumor mutation burden, checkpoints, and immune cell infiltration. An mRNA–miRNA network was built to identify an miR-203a-3p/LDHD/LYRM7 regulatory axis in BC.

Conclusion: In conclusion, we constructed a novel 3-LMRG signature and nomogram that can be used to predict the prognosis of BC patients. In addition, the signature is closely related to the immune microenvironment, which may provide new insight into future anticancer therapies.

Research progress on immunotherapy in triple‑negative breast cancer (Review)

Triple-negative breast cancer (TNBC) is a highly heterogeneous and aggressive malignancy. Due to the absence of estrogen receptors and progesterone receptors and the lack of overexpression of human epidermal growth factor receptor 2, TNBC responds poorly to endocrine and targeted therapies. As a neoadjuvant therapy, chemotherapy is usually the only option for TNBC; however, chemotherapy may induce tumor resistance. The emergence of immunotherapy as an adjuvant therapy is expected to make up for the deficiency of chemotherapy. Most of the research on immunotherapies has been performed on advanced metastatic TNBC, which has provided significant clinical benefits. In the present review, possible immunotherapy targets and ongoing immunotherapy strategies were discussed. In addition, progress in research on immune checkpoint inhibitors in early TNBC was outlined.

Occupational Low-Dose Radiation Affects the Expression of Immune Checkpoint of Medical Radiologists

The purpose of this study was to investigate the expression of immune checkpoint cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and T cell immunoglobulin and mucin domain 3 (TIM-3) in the peripheral blood T lymphocytes of medical radiologists. The study incorporated 100 male medical radiologists and 107 male healthy controls. The expressions of CTLA-4 and TIM-3 among CD4+ and CD8+ lymphocytes were detected by flow cytometry. The expression levels of CTLA-4 and TIM-3 in the CD4+T cells of radiation workers were lower than those of healthy controls (p < 0.05). Correlation analysis showed that the CD8+CTLA-4 expression level was significantly positively correlated with individual cumulative dose (rs = 0.260, p = 0.001, <0.05), while the expression level of CD8+TIM-3 was negatively correlated (rs = −0.180, p = 0.027, <0.05). Low-dose radiation exposure affects the expression of CTLA-4 and TIM-3 in human peripheral blood T lymphocytes. Future studies need to focus on exploring the mechanisms by which CTLA-4 and TIM-3 expression changes in response to low-dose radiation exposure.

Combination therapy with immune checkpoint inhibitors (ICIs); a new frontier

Recently, immune checkpoint inhibitors (ICIs) therapy has become a promising therapeutic strategy with encouraging therapeutic outcomes due to their durable anti-tumor effects. Though, tumor inherent or acquired resistance to ICIs accompanied with treatment-related toxicities hamper their clinical utility. Overall, about 60-70% of patients (e.g., melanoma and lung cancer) who received ICIs show no objective response to intervention. The resistance to ICIs mainly caused by alterations in the tumor microenvironment (TME), which in turn, supports angiogenesis and also blocks immune cell antitumor activities, facilitating tumor cells' evasion from host immunosurveillance. Thereby, it has been supposed and also validated that combination therapy with ICIs and other therapeutic means, ranging from chemoradiotherapy to targeted therapies as well as cancer vaccines, can capably compromise tumor resistance to immune checkpoint blocked therapy. Herein, we have focused on the therapeutic benefits of ICIs as a groundbreaking approach in the context of tumor immunotherapy and also deliver an overview concerning the therapeutic influences of the addition of ICIs to other modalities to circumvent tumor resistance to ICIs.

Differential Response of MDA-MB-231 and MCF-7 Breast Cancer Cells to In Vitro Inhibition with CTLA-4 and PD-1 through Cancer-Immune Cells Modified Interactions

Drugs targeting immune checkpoint molecules have been found effective in melanoma, lung cancer, and other malignancies treatment. Recent studies on breast cancer demonstrated the significance of inhibitory anti-CTLA-4 and anti-PD-1 in the regulation of disease progression. However, seemingly the same types of breast cancer do not always respond unambiguously to immunotherapy. Thus, here we set out to analyze the in vitro effects of inhibiting CTLA-4 and PD-1 on interactions between co-cultured lymphocytes and two selected breast adenocarcinoma cell lines. Breast cancer cells were co-cultured with lymphocytes to evaluate the effects of CTLA-4 and PD-1 inhibition. Proliferation, cell cycle, and viability assessment were measured in cancer cells. IFN-gamma, IL-10, perforin, granzyme B production, and CTLA-4 and PD-1 expression were analyzed in lymphocytes. We found that administration of anti-CTLA-4 improved the anti-cancer activity of T cells with reduced proliferation and viability of MDA-MB-231. Lack of response was observed in the context of MCF-7. In addition, differential expression of checkpoint proteins was found between studied cancer cells lines. Inhibition of molecules was followed by IL-10 and IFN-gamma decrease in lymphocytes co-cultured with MDA-MB-231, not demonstrated in reference to MCF-7. Furthermore, CTLA-4 blockage was associated with reduction of CTLA-4+ and PD-1+ lymphocytes in MDA-MB-231, with a significant increase in MCF-7, reduced by anti-PD-1. Altogether, our study revealed that anti-CTLA-4 and anti-PD-1 treatment can improve lymphocytes effects on breast cancer cells. Favorable effects seemed to be related to breast cancer cells features as differential responses were reported. Novel blocking antibodies strategies should be tested for more effective cancer inhibition.