Optimizing choices and sequences in the diagnostic-therapeutic landscape of advanced triple-negative breast cancer: An Italian consensus paper and critical review

Genomic characterization reveals distinct mutational landscapes and therapeutic implications between different molecular subtypes of triple-negative breast cancer

Triple-negative breast cancer (TNBC) has high heterogeneity, poor prognosis, and limited treatment success. Recently, an immunohistochemistry-based surrogate classification for the "Fudan University Shanghai Cancer Center (FUSCC) subtyping" has been developed and is considered more suitable for clinical application. Seventy-one paraffin-embedded sections of surgically resected TNBC were classified into four molecular subtypes using the IHC-based surrogate classification. Genomic analysis was performed by targeted next-generation sequencing and the specificity of the subtypes was explored by bioinformatics, including survival analysis, multivariate Cox regression, pathway enrichment, Pyclone analysis, mutational signature analysis and PHIAL analysis. AKT1 and BRCA1 mutations were identified as independent prognostic factors in TNBC. TNBC molecular subtypes encompass distinct genomic landscapes that show specific heterogeneities. The luminal androgen receptor (LAR) subtype was associated with mutations in PIK3CA and PI3K pathways, which are potentially sensitive to PI3K pathway inhibitors. The basal-like immune-suppressed (BLIS) subtype was characterized by high genomic instability and the specific possession of signature 19 while patients in the immunomodulatory (IM) subtype belonged to the PD-L1 ≥ 1% subgroup with enrichment in Notch signaling, suggesting a possible benefit of immune checkpoint inhibitors and Notch inhibitors. Moreover, mesenchymal-like (MES) tumors displayed enrichment in the receptor tyrosine kinase (RTK)-RAS pathway and potential sensitivity to RTK pathway inhibitors. The findings suggest potential treatment targets and prognostic factors, indicating the possibility of TNBC stratified therapy in the future.

Facing the conundrum: which first-line therapy should be used for patients with metastatic triple-negative breast cancer carrying germline BRCA mutation?

Pembrolizumab combined with chemotherapy has been established as the preferred first-line therapy for treating metastatic triple-negative breast cancer (mTNBC) with programmed cell death ligand-1 (PD-L1)-positive disease since its approval for that indication. However, the optimal sequencing of therapy remains an unanswered question for a subset of mTNBC patients who harbor germline breast cancer gene 1/2 (BRCA1/2; gBRCA1/2) mutation. This article aims to offer insights into the optimal therapy sequencing for mTNBC patients with gBRCA1/2 mutations and its impact on clinical decision-making. The perspective offered is based on the best currently available data and propose a practical algorithm to guide the management of this subgroup in the frontline setting.

Cell Line-Dependent Adhesion and Inhibition of Proliferation on Carbon-Based Nanofilms

Introduction

Disorganisation of the extracellular matrix (ECM) is strongly connected to tumor progression. Even small-scale changes can significantly influence the adhesion and proliferation of cancer cells. Therefore, the use of biocompatible nanomaterials capable of supporting and partially replenishing degraded ECM might be essential to recover the niche after tumor resection. The objective of this study was to evaluate the influence of graphene, graphene oxide, fullerene, and diamond nanofilms on breast cancer and glioblastoma grade IV cell lines.

Methods

Nanomaterials were characterized using SEM and TEM techniques; zeta potential analysis was also performed. Nanofilms of graphene, fullerene, and diamond nanoparticles were also characterized using AFM. The toxicity was tested on breast cancer MDA.MB.231 and glioblastoma grade IV U-87 MG cell lines, using LDH assay and by counting stained dead cells in bioprinted 3D models. The following parameters were analyzed: proliferation, adhesion to the nanofilm, and adhesion to particular ECM components covered with diamond nanoparticles.

Results and Discussion

Our studies demonstrated that nanofilms of graphene and diamond nanoparticles are characterized by cell-specific toxicity. Those nanomaterials were non-toxic to MDA.MB.231 cells. After applying bioprinted 3D models, diamond nanoparticles were not toxic for both cell lines. Nanofilms made of diamond nanoparticles and graphene inhibit the proliferation of MDA.MB.231 cells after 48 and 72 hours. Increased adhesion on nanofilm made of diamond nanoparticles was only observed for MDA.MB.231 cells after 30 and 60 minutes from seeding the cells. However, analysis of adhesion to certain ECM components coated with diamond nanoparticles revealed enhanced adhesion to tenascin and vitronectin for both tested cell lines.

Conclusion

Our studies show that nanofilm made of diamond nanoparticles is a non-toxic and pro-adhesive nanomaterial that might stabilize and partially replenish the niche after breast tumor resection as it enhances the adhesion of breast cancer cells and inhibits their proliferation.

Tumor Infiltrating Lymphocytes (TILS) and PD-L1 Expression in Breast Cancer: A Review of Current Evidence and Prognostic Implications from Pathologist's Perspective

With the rise of novel immunotherapies able to stimulate the antitumor immune response, increasing literature concerning the immunogenicity of breast cancer has been published in recent years. Numerous clinical studies have been conducted in order to identify novel biomarkers that could reflect the immunogenicity of BC and predict response to immunotherapy. In this regard, TILs have emerged as an important immunological biomarker related to the antitumor immune response in BC. TILs are more frequently observed in triple-negative breast cancer and HER2+ subtypes, where increased TIL levels have been linked to a better response to neoadjuvant chemotherapy and improved survival. PD-L1 is a type 1 transmembrane protein ligand expressed on T lymphocytes, B lymphocytes, and antigen-presenting cells and is considered a key inhibitory checkpoint involved in cancer immune regulation. PD-L1 immunohistochemical expression in breast cancer is observed in about 10-30% of cases and is extremely variable based on tumor stage and molecular subtypes. Briefly, TNBC shows the highest percentage of PD-L1 positivity, followed by HER2+ tumors. On the other hand, PD-L1 is rarely expressed (0-10% of cases) in hormone-receptor-positive BC. The prognostic role of PD-L1 expression in BC is still controversial since different immunohistochemistry (IHC) clones, cut-off points, and scoring systems have been utilized across published studies. In the present paper, an extensive review of the current knowledge of the immune landscape of BC is provided. TILS and PD-L1 expression across different BC subtypes are discussed, providing a guide for their pathological assessment and reporting.

Suppressing Src-Mediated EGFR Signaling by Sustained Calcium Supply Targeting Triple-Negative Breast Cancer

Src is emerging as a promising target in triple-negative breast cancer (TNBC) treatment because it activates survival signaling linked to the epidermal growth factor receptor. In this study, the effect of calcium supply on Src degradation was investigated to confirm underlying mechanisms and anticancer effects targeting TNBC. MDA-MB-231 cells, the TNBC cell line, were used. Calcium supply was feasible through lactate calcium salt (CaLac), and the applicable calcium concentration was decided by changes in the viability with different doses of CaLac. Expression of signaling molecules mediated by calcium-dependent Src degradation was observed by Western blot analysis and immunocytochemistry, and the recovery of the signaling molecules was confirmed following calpeptin treatment. The anticancer effect was investigated in the xenograft animal model. Significant suppression of Src was induced by calcium supply, followed by a successive decrease in the expression of epithelial growth factor receptor, RAS, extracellular signal-regulated kinase, and nuclear factor kappa B. Then, the suppression of cyclooxygenase-2 contributed to a significant deactivation of the prostaglandin E2 receptors. These results suggest that calcium supply has the potential to reduce the risk of TNBC. However, as this study is at an early stage to determine clinical applicability, close consideration is needed.