Therapeutic pattern and progress of neoadjuvant treatment for triple-negative breast cancer

The effect of silencing the Tip60 gene on the response to radiotherapy in breast cancer cells

Since patients with triple-negative breast cancer do not respond to hormone therapy, the main treatment method is the combination of chemotherapy and radiotherapy. Because the DNA of the tumor cell is the target in both some chemotherapeutics and radiotherapy, problems may occur in individuals with a high DNA repair pathway. It is suggested that high expression of the Tip60 gene, which has an important role in repairing DNA damage, will increase the repair of DNA double-strand breaks in tumor cells, especially during radiotherapy treatment, thus reducing the response to treatment and adversely affecting treatment. In this study, for the first time, the role of the silenced and active Tip60 gene in response to radiotherapy in MDA-MB-231 and MCF-7 cells was investigated. For this purpose, the Tip60 gene was silenced by applying siRNA to the cell lines and UV was applied. In the study, cytotoxicity and DNA breaks were measured by MTT and COMET methods, and mRNA and protein expression values were measured by PCR and Raman spectrophotometer in silenced, unsilenced, UV-treated, and non-UV-treated cell lines. According to the results of the study, increased DNA damage was observed in MCF-7 cell lines in which the Tip60 gene was silenced, and radiotherapy was applied, compared to the cell lines with the Tip60 gene active. It was observed that DNA damage in MDA-MB-231 cell lines was less than in cell lines with the active Tip60 gene.

Paraoxonase-2 is upregulated in triple negative breast cancer and contributes to tumor progression and chemoresistance

Triple negative breast cancer (TNBC) displays a high aggressive behavior, tendency to relapse and early metastasize, leading to poor prognosis. The lack of estrogen receptors, and human epidermal growth factor receptor 2, prevents the use of endocrine or molecular targeted therapy, being therapeutical options for TNBC managements mostly limited to surgery, radiotherapy and mainly chemotherapy. While an important number of TNBCs initially responds to chemotherapy, they are prone to develop chemoresistance over the time. Thus, there is an urgent need to identify novel molecular targets to improve the outcome of chemotherapy in TNBC. In this work we focused on the enzyme paraoxonase-2 (PON2) which has been reported to be overexpressed in several tumors contributing to cancer aggressiveness and chemoresistance. Through a case-control study, we analyzed PON2 immunohistochemical expression in breast cancer molecular subtypes Luminal A, Luminal B, Luminal B HER2+, HER2 + and TNBC. Subsequently, we evaluated the in vitro effect of PON2 downregulation on cell proliferation and response to chemotherapeutics. Our results showed that the PON2 expression levels were significantly upregulated in the infiltrating tumors related to the subtypes Luminal A, HER2+ and TNBC compared to the healthy tissue. Furthermore, PON2 downregulation led to a decrease in cell proliferation of breast cancer cells, and significantly enhanced the cytotoxicity of chemotherapeutics on the TNBC cells. Although further analyses are necessary to deeply understand the mechanisms by which the enzyme could participate to breast cancer tumorigenesis, our results seem to demonstrate that PON2 could represent a promising molecular target for TNBC treatment.

The impact of HER2-low status on response to neoadjuvant chemotherapy in clinically HER2-negative breast cancer

PURPOSE

Low expression of HER2 (HER2-low expression) in breast cancer (BC) has unique biological characteristics. However, whether HER2-low expression has an impact on neoadjuvant chemotherapy (NACT) in HER2-negative breast cancer remains unclear.

METHODS

This study reviewed the clinicopathological data of patients with BC treated with NACT at a single hospital from January 2018 to July 2022. Baseline patient characteristics, efficacy of NACT, and survival data were compared between the HER2-0 and HER2-low groups. The impact of NACT on HER2 status also was investigated. Subgroup analyses based on hormone receptor (HR) status were performed to explore the impact of HR signaling on HER2 status during chemotherapy.

RESULTS

The progesterone receptor-positive rate in the HER2-low group was significantly higher than that in HER2-0 group. The local treatment response of the HER2-low group was worse, but the disease-free survival rate of the HER2-low group was significantly better than that of the HER2-0 group. The proportion of patients with increased HER2 immunohistochemistry score after NACT was significantly higher in the HER2-0 group. Subgroup analysis showed that the efficacy of chemotherapy in HR + patients was significantly worse than in HR- patients, and HR + patients had a higher proportion of increased HER2 immunohistochemistry score after chemotherapy. Mechanistic studies suggested that MLH1 expression loss during chemotherapy might link HR signaling and regulation of HER2 expression.

CONCLUSIONS

We found that HER2-low expressing BC exhibits differential sensitivity to chemotherapy compared to HER2-0 expressing BC. The regulation of HER2 expression by HR signaling may mediate aspects of chemoresistance.

Rationale and Clinical Research Progress on PD-1/PD-L1-Based Immunotherapy for Metastatic Triple-Negative Breast Cancer

Metastatic triple-negative breast cancer (mTNBC), a highly aggressive and malignant tumor, currently lacks an effective treatment. There has been some progress in the treatment of mTNBC with programmed death receptor-1/programmed death ligand-1 (PD-1/PD-L1) immunotherapy in recent years. The combination of PD-1/PD-L1 inhibitors with other therapies is a noteworthy treatment strategy. Immunotherapy in combination with chemotherapy or small-molecule inhibitors still faces many challenges. Additionally, there are some new immunotherapy targets in development. We aimed to further evaluate the effectiveness and usefulness of immunotherapy for treating mTNBC and to propose new immunotherapy strategies. This review explains the rationale and results of existing clinical trials evaluating PD-1/PD-L1 inhibitors alone or in combination for the treatment of mTNBC. For patients with aggressive tumors and poor health, PD-1/PD-L1 inhibitors, either alone or in combination with other modalities, have proven to be effective. However, more research is needed to explore more effective immunotherapy regimens that will lead to new breakthroughs in the treatment of mTNBC.