Clinical Outcomes for Patients With Metastatic Breast Cancer Treated With Immunotherapy Agents in Phase I Clinical Trials

Antibody-drug conjugates targeting SSEA-4 inhibits growth and migration of SSEA-4 positive breast cancer cells

Although breast cancer treatment has evolved significantly in recent years, drug resistance remains a major challenge. To identify new targets for breast cancer, we found that stage-specific embryonic antigen 4 (SSEA-4) is expressed in all subtypes of breast cancer cell lines, and the increased expression of the associated enzymes β3GalT5 and ST3Gal2 correlates with poor recurrence-free survival (RFS) in breast cancer. We also found that SSEA-4 antibodies can be rapidly internalized into breast cancer cells, a property that makes SSEA-4 an attractive target for antibody-drug conjugates (ADCs). Furthermore, the SSEA-4 antibody conjugated to the anticancer agents showed efficacy against SSEA-4-positive breast cancer cells, including those resistant to PARP inhibitor, trastuzumab, and CDK7 inhibitor. In addition, SSEA-4 ADCs showed no efficacy in β3GalT5-knockout MDA-MB-231 cells, highlighting the essential role of SSEA-4 as the target antigen for ADCs activity. Our work shows that SSEA-4-ADCs could be a therapeutic option for breast cancers.

Mass Spectrometry-Based Proteomics for Classification and Treatment Optimisation of Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) presents a significant medical challenge due to its highly invasive nature, high rate of metastasis, and lack of drug-targetable receptors, which together lead to poor prognosis and limited treatment options. The traditional treatment guidelines for early TNBC are based on a multimodal approach integrating chemotherapy, surgery, and radiation and are associated with low overall survival and high relapse rates. Therefore, the approach to treating early TNBC has shifted towards neoadjuvant treatment (NAC), given to the patient before surgery and which aims to reduce tumour size, reduce the risk of recurrence, and improve the pathological complete response (pCR) rate. However, recent studies have shown that NAC is associated with only 30% of patients achieving pCR. Thus, novel predictive biomarkers are essential if treatment decisions are to be optimised and chemotherapy toxicities minimised. Given the heterogeneity of TNBC, mass spectrometry-based proteomics technologies offer valuable tools for the discovery of targetable biomarkers for prognosis and prediction of toxicity. These biomarkers can serve as critical targets for therapeutic intervention. This review aims to provide a comprehensive overview of TNBC diagnosis and treatment, highlighting the need for a new approach. Specifically, it highlights how mass spectrometry-based can address key unmet clinical needs by identifying novel protein biomarkers to distinguish and early prognostication between TNBC patient groups who are being treated with NAC. By integrating proteomic insights, we anticipate enhanced treatment personalisation, improved clinical outcomes, and ultimately, increased survival rates for TNBC patients.

Impact of NDUFAF6 on breast cancer prognosis: linking mitochondrial regulation to immune response and PD-L1 expression

BACKGROUND

Breast cancer is a major global health concern, and there is a continuous search for novel biomarkers to predict its prognosis. The mitochondrial protein NDUFAF6, previously studied in liver cancer, is now being investigated for its role in breast cancer. This study aims to explore the expression and functional significance of NDUFAF6 in breast cancer using various databases and experimental models.

METHODS

We analyzed breast cancer samples from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and Human Protein Atlas (HPA) databases, supplemented with immunohistochemistry (IHC) staining to assess NDUFAF6 expression. A breast cancer cell xenograft mouse model was used to evaluate tumor growth, apoptosis, and NDUFAF6 expression. Survival probabilities were estimated through Kaplan-Meier plots and Cox regression analysis. A Protein-Protein Interaction (PPI) network was constructed, and differentially expressed genes related to NDUFAF6 were analyzed using GO, KEGG, and GSEA. The relationship between NDUFAF6 expression, immune checkpoints, and immune infiltration was also evaluated.

RESULTS

NDUFAF6 was found to be overexpressed in breast cancer patients and in the xenograft mouse model. Its expression correlated with worse clinical features and prognosis. NDUFAF6 expression was an independent predictor of breast cancer outcomes in both univariate and multivariate analyses. Functionally, NDUFAF6 is implicated in several immune-related pathways. Crucially, NDUFAF6 expression correlated with various immune infiltrating cells and checkpoints, particularly promoting PD-L1 expression by inhibiting the NRF2 signaling pathway.

CONCLUSION

The study establishes NDUFAF6 as a potential prognostic biomarker in breast cancer. Its mechanism of action, involving the inhibition of NRF2 to upregulate PD-L1, highlights its significance in the disease's progression and potential as a target for immunotherapy.

MRCK as a Potential Target for Claudin-Low Subtype of Breast Cancer

To find new molecular targets for triple negative breast cancer (TNBC), we analyzed a large-scale drug screening dataset based on breast cancer subtypes. We discovered that BDP-9066, a specific MRCK inhibitor (MRCKi), may be an effective drug against TNBC. After confirming the efficacy and specificity of BDP-9066 against TNBC in vitro and in vivo, we further analyzed the underlying mechanism of specific activity of BDP-9066 against TNBC. Comparing the transcriptome of BDP-9066-sensitive and -resistant cells, the activation of the focal adhesion and YAP/TAZ pathway were found to play an important role in the sensitive cells. Furthermore, YAP/TAZ is indeed repressed by BDP-9066 in the sensitive cells, and active form of YAP suppresses the effects of BDP-9066. YAP/TAZ expression and activity are high in TNBC, especially the Claudin-low subtype, consistent with the expression of focal adhesion-related genes. Interestingly, NF-κB functions downstream of YAP/TAZ in TNBC cells and is suppressed by BDP-9066. Furthermore, the PI3 kinase pathway adversely affected the effects of BDP-9066 and that alpelisib, a PI3 kinase inhibitor, synergistically increased the effects of BDP-9066, in PIK3CA mutant TNBC cells. Taken together, we have shown for the first time that MRCKi can be new drugs against TNBC, particularly the Claudin-low subtype.

Immune-Checkpoint Inhibitors: A New Line of Attack in Triple-Negative Breast Cancer

Poor prognosis is a distinctive feature of triple-negative breast cancer (TNBC). Chemotherapy has long represented the main and unique treatment for patients with TNBC. Recently, immune checkpoint inhibitors (ICIs) were investigated in several clinical trials and were approved for clinical use in TNBC patients that express programmed cell death protein-1 (PD-1) in combination with chemotherapy in the first-line setting. ICIs are also being investigated in the neoadjuvant and adjuvant settings for TNBC. This chapter aims to discuss different ICIs used to treat all TNBC stages to date.

Tumour Microenvironment-Immune Cell Interactions Influencing Breast Cancer Heterogeneity and Disease Progression

Breast cancer is a complex, dynamic disease that acquires heterogeneity through various mechanisms, allowing cancer cells to proliferate, survive and metastasise. Heterogeneity is introduced early, through the accumulation of germline and somatic mutations which initiate cancer formation. Following initiation, heterogeneity is driven by the complex interaction between intrinsic cellular factors and the extrinsic tumour microenvironment (TME). The TME consists of tumour cells and the subsequently recruited immune cells, endothelial cells, fibroblasts, adipocytes and non-cellular components of the extracellular matrix. Current research demonstrates that stromal-immune cell interactions mediated by various TME components release environmental cues, in mechanical and chemical forms, to communicate with surrounding and distant cells. These interactions are critical in facilitating the metastatic process at both the primary and secondary site, as well as introducing greater intratumoral heterogeneity and disease complexity by exerting selective pressures on cancer cells. This can result in the adaptation of cells and a feedback loop to the cancer genome, which can promote therapeutic resistance. Thus, targeting TME and immune-stromal cell interactions has been suggested as a potential therapeutic avenue given that aspects of this process are somewhat conserved between breast cancer subtypes. This mini review will discuss emerging ideas on how the interaction of various aspects of the TME contribute to increased heterogeneity and disease progression, and the therapeutic potential of targeting the TME.

Comparison of outcomes in patients with luminal type breast cancer treated with a gonadotropin-releasing hormone analog or bilateral salpingo-oophorectomy: A cohort retrospective study

Introduction

Premenopausal patients with hormone receptor-positive breast cancer require ablation therapy via a pharmacological or surgical approach. Data comparing outcomes between treatment with gonadotropin-releasing hormone (GnRH) analogs and treatment with bilateral salpingo-oophorectomy (BSO) in Indonesia remains limited. Therefore, this study aimed to compare incidence of local recurrence and metastasis, and overall survival (OS) in patients with luminal type breast cancer treated using the two approaches.

Methods

This observational retrospective cohort study examined 100 premenopausal patients diagnosed with luminal type hormone receptor-positive breast cancer who registered at Dr. Wahidin Sudirohusodo Hospital and its networking hospitals in Makassar City from January to December 2017.

Result

Among the 100 study patients, 50 were given GnRH analogs and 50 underwent BSO. Incidence of local recurrence (P = 0.408) and metastasis (P = 0.419) did not significantly differ between the GnRH analog and BSO groups, although the incidence of local recurrence was higher in the GnRH analog group (68% vs. 58%) and incidence of metastasis was higher in the BSO group (24% vs 19%). The 5-year survival rate did not significantly differ between the GnRH analog and BSO groups.

Conclusion

Incidence of local recurrence and metastasis, and 5-year survival rate did not significantly differ between premenopausal breast cancer patients treated using a GnRH analog and those treated with BSO. Further large-scale studies to compare the efficacy and safety of both approaches are warranted.

Shedding light on triple-negative breast cancer with Trop2-targeted antibody-drug conjugates

Triple-negative breast cancer (TNBC) is well-known as the most aggressive subtype of breast cancer. Because TNBC does not express Her2, estrogen receptor, and progesterone receptors, there had been no effective U.S. Food and Drug Administration-approved targeted therapy for it until PARP inhibitors and two PD-1/PD-L1 monoclonal antibodies were approved for treatment of TNBC. Most recently, an antibody-drug conjugate (ADC), called sacituzumab govitecan (SG), was approved for the treatment of TNBC patients previously received chemotherapy with advanced disease. SG consists of an anti-trophoblast cell-surface antigen 2 (Trop2) antibody conjugated with a topoisomerase I inhibitor, SN-38, which is diffused out of the targeted Trop2 positive cancer cells and induces the bystander killing effect on surrounding cells regardless of their Trop2 expression status. In the Phase III clinical trial, TNBC patients treated with SG showed significantly longer progression-free and overall survival compared to those who were received chemotherapy. In the present review, we summarized the cellular function and signaling of Trop2, the mechanism of action of SG, and the clinical trials of SG that led to its quick approval for TNBC. In addition, we introduced the current ongoing clinical trials of SG as well as another Trop2 ADC, which has potential to overcome some disadvantages of SG.

Peripheral Blood Transcriptome in Breast Cancer Patients as a Source of Less Invasive Immune Biomarkers for Personalized Medicine, and Implications for Triple Negative Breast Cancer

Transcriptome studies of peripheral blood cells can advance our understanding of the systemic immune response to the presence of cancer and the mechanisms underlying cancer onset and progression. This enables the identification of novel minimally invasive immune biomarkers for early cancer detection and personalized cancer management and may bring forward new immunotherapy options. Recent blood gene expression analyses in breast cancer (BC) identified distinct patient subtypes that differed in the immune reaction to cancer and were distinct from the clinical BC subtypes, which are categorized based on expression of specific receptors on tumor cells. Introducing new BC subtypes based on peripheral blood gene expression profiles may be appropriate, since it may assist in BC prognosis, the identification of patients likely to benefit from immunotherapy, and treatment efficacy monitoring. Triple-negative breast cancer (TNBC) is an aggressive, heterogeneous, and difficult-to-treat disease, and identification of novel biomarkers for this BC is crucial for clinical decision-making. A few studies have reported TNBC-enriched blood transcriptional signatures, mostly related to strong inflammation and augmentation of altered immune signaling, that can differentiate TNBC from other classical BC subtypes and facilitate diagnosis. Future research is geared toward transitioning from expression signatures in unfractionated blood cells to those in immune cell subpopulations.