The immune microenvironment characterisation and dynamics in hormone receptor-positive breast cancer before and after neoadjuvant endocrine therapy

Tumor Microenvironment Modulation by Tumor-Associated Macrophages: Implications for Neoadjuvant Chemotherapy Response in Breast Cancer

Background

Tumor-associated macrophages (TAMs) constitute an important part of the tumor microenvironment of breast cancer (BC), and they play an essential role in modulating tumor growth and invasion. However, the role of TAMs in neoadjuvant chemotherapy (NAC) has not been fully elucidated. Therefore, the aim of this study was to assess the function of TAM subtypes and investigate their role in the response to NAC in BC.

Methods

Presence of TAMs was examined immunohistochemically (IHC) in pre- and post- NAC treatment tumor tissue in a cohort of 138 BC patients. IHC staining with monoclonal antibodies for CD68 and CD163 were performed. Positivity was defined as staining > 1% TAMs in stroma and tumor cell nests. Response to NAC was evaluated according to tumor size change and Residual Cancer Burden (RCB) index.

Results

CD68+ and CD163+ TAMs decreased significantly in both the stroma and tumor nests (TN) after NAC. The median CD68+ TAMs in the stroma decreased significantly from 5% to 1% (p < 0.005), while CD163+ TAMs showed a marked reduction from 20% to 5% (p < 0.001). Post-NAC, the persistence of CD68+ and CD163+ TAMs in the stroma was strongly correlated with larger residual tumor size (p < 0.005 and p < 0.001, respectively). Changes in CD163+ TAM levels in the stroma were significantly associated with RCB classes (p < 0.005). Pre-NAC, CD163+ TAMs in the stroma and TN showed a significant association with TILs; however, no correlations with TILs were observed post-NAC.

Conclusion

This study highlights the critical role of TAMs dynamics in shaping NAC response in BC. Notably, CD163+ TAMs may emerge as pivotal players in mechanisms of chemotherapy resistance and response, underscoring their potential as biomarkers and therapeutic targets in breast cancer treatment.

Recurrence score-predicted value derived from estrogen receptor, tumor-infiltrating lymphocytes, progesterone receptor, and Ki-67 may substitute for the Oncotype DX recurrence score in estrogen receptor (ER)+/human epidermal growth factor receptor 2 (HER2)- breast cancer

Oncotype DX is the only multigene assay supported by the National Comprehensive Cancer Network (USA) with Level 1 evidence for use on node-negative and postmenopausal node-positive patients with estrogen receptor (ER)+/human epidermal growth factor receptor 2 (HER2)-breast cancer to predict the prognosis and to estimate chemotherapy add-on effects. However, the test's high cost prevents its use in most cases. Therefore, we aimed to obtain an alternative recurrence score (RS) prediction formula using the optimal clinicopathological factors. We retrospectively reviewed data of 81 patients with ER+/HER2- primary breast cancer in our hospital where Oncotype DX RS was measured. Stepwise multivariate linear regression analysis was conducted with several selected clinicopathological factors of 60 consecutive cases in the training group. The obtained RS-predicted values were validated against Oncotype DX RS using 21 additional consecutive cases. The RS prediction formula derived from the combination of ER, tumor-infiltrating lymphocytes (TILs), progesterone receptor (PgR), and Ki-67-labeling index produced a favorable model with a correlation coefficient (r) of 0.731103 for the Oncotype DX RS (p = 0.0002) and an adjusted R2 coefficient of 0.510013. The RS-predicted values and the actual Oncotype DX RS were classified into four 2 × 2 groups, by using an RS of 26 as a threshold for adding chemotherapy with a concordance rate of 95.2 % (20/21) and a kappa coefficient of 0.829. RS-predicted values of combined ER, TILs, PgR, and Ki-67 may be an appropriate substitute for Oncotype DX RS in certain situations.

CDK4/6 inhibitors in HR-positive breast cancer immunotherapy

Breast cancer is the most prevalent malignant tumour among women. Approximately 70 % of patients are hormone receptor (HR)-positive and undergo endocrine therapy as the main form of treatment; however, the efficacy of this type of therapy is limited by some factors, such as drug resistance and complex tumour microenvironments. Using network pharmacology and molecular docking, this study examined how CDK4/6 inhibitors enhance the effects of immunotherapy for HR-positive breast cancer, focusing on their effects on the tumour microenvironment (TME) and immune cell activity. CDK4/6 inhibitor influence crucial signalling pathways, including TP53 and EGFR, underscoring their importance in modulating immune responses and combating drug resistance. Our analysis revealed that the combination of CDK4/6 inhibitors with other immunotherapies, such as immune checkpoint inhibitors, might play an important role in improving the effectiveness of treatment in patients with cancer. This study provides new perspectives on treatment options for HR-positive breast cancers, promoting ongoing research and improvements in therapeutic approaches.

Influence of tumor microenvironment on the different breast cancer subtypes and applied therapies

Despite the significant improvements made in breast cancer therapy during the last decades, this disease still has increasing incidence and mortality rates. Different targets involved in general processes, like cell proliferation and survival, have become alternative therapeutic options for this disease, with some of them already used in clinic, like the CDK4/6 inhibitors for luminal A tumors treatment. Nevertheless, there is a demand for novel therapeutic strategies focused not only on tumor cells, but also on their microenvironment. Tumor microenvironment (TME) is a very complex and dynamic system that, more than surrounding and supporting tumor cells, actively participates in tumor development and progression. During the last decades, it has become clear that the cellular and acellular components of TME differ between the various breast cancer subtypes and shape the differences regarding their severity and prognosis. The pivotal role of the TME in controlling tumor growth and influencing responses to therapy represents a potential source for novel targets and therapeutic strategies. In this review, we present a description of the multiple therapeutic options used for different breast cancer subtypes, as well as the influence that the TME may exert on the development of the disease and on the response to the distinct therapies, which in some cases may explain their failure by the occurrence of relapses and resistance. Furthermore, the ongoing studies focused on the use of TME components for developing potential cancer treatments are described.