Breast cancer and immunology: biomarker and therapeutic developments

Novel markers in breast pathology

Breast pathology is an ever-expanding database of information which includes markers, or biomarkers, that detect or help treat the disease as prognostic or predictive information. This review focuses on these aspects of biomarkers which are grounded in immunohistochemistry, liquid biopsies and next-generation sequencing.

p110δ PI3K as a therapeutic target of solid tumours

From the time of first characterization of PI3K as a heterodimer made up of a p110 catalytic subunit and a regulatory subunit, a wealth of evidence have placed the class IA PI3Ks at the forefront of drug development for the treatment of various diseases including cancer. The p110α isoform was quickly brought at the centre of attention in the field of cancer research by the discovery of cancer-specific gain-of-function mutations in PIK3CA gene in a range of human solid tumours. In contrast, p110δ PI3K was placed into the spotlight of immunity, inflammation and haematologic malignancies because of the preferential expression of this isoform in leucocytes and the rare mutations in PIK3CD gene. The last decade, however, several studies have provided evidence showing that the correlation between the PIK3CA mutations and the response to PI3K inhibition is less clear than originally considered, whereas concurrently an unexpected role of p110δ PI3K in solid tumours has being emerging. While PIK3CD is mostly non-mutated in cancer, the expression levels of p110δ protein seem to act as an intrinsic cancer-causing driver in various solid tumours including breast, prostate, colorectal and liver cancer, Merkel-Cell carcinoma, glioblastoma and neurobalstoma. Furthermore, p110δ selective inhibitors are being studied as potential single agent treatments or as combination partners in attempt to improve cancer immunotherapy, with both strategies to shown great promise for the treatment of several solid tumours. In this review, we discuss the evidence implicating the p110δ PI3K in human solid tumours, their impact on the current state of the field and the potential of using p110δ-selective inhibitors as monotherapy or combined therapy in different cancer contexts.

High expression of CD47 in triple negative breast cancer is associated with epithelial-mesenchymal transition and poor prognosis

CD47 functions as a dominant anti-engulfment signal on tumour cells and is overexpressed in various malignant tumours. However, the expression and functional significance of CD47 in triple-negative breast cancer (TNBC) is not completely understood. In the present study, CD47 was demonstrated to be overexpressed in TNBC solid tumours. Moreover, increased CD47 expression was significantly associated with an advanced tumour-node-metastasis stage, lymph node involvement and recurrence. Moreover, CD47 was an unfavourable and independent prognostic factor for 5-year disease-free survival in patients with TNBC. In addition, the expression of CD47 was associated with several markers of epithelial-mesenchymal transition (EMT). The present study was the first to demonstrate an association between increased expression of CD47 with EMT and poor prognosis of TNBC. Thus, CD47 may be a potential prognostic biomarker and therapeutic target for TNBC.

Immunotherapy for HER2-positive breast cancer: recent advances and combination therapeutic approaches

Cancer immunotherapy has evolved dramatically with improved understanding of immune microenvironment and immunosurveillance. The immunogenicity of breast cancer is rather heterogeneous. Specific subtypes of breast cancer such as estrogen receptor (ER)-negative, human EGF receptor 2 (HER2)-positive, and triple-negative breast cancer (TNBC) have shown evidence of immunogenicity based on tumor–immune interactions. Several preclinical and clinical studies have explored the potential for immunotherapy to improve the clinical outcomes for different subtypes of breast cancer. This review describes the immune microenvironment of HER2-positive breast cancer and summarizes recent clinical advances of immunotherapeutic treatments in this breast cancer subtype. The review provides rationale and ongoing clinical evidence to the use of immune checkpoint inhibitors, therapeutic vaccines, and adoptive T cell immunotherapy in breast cancer. In addition, the present paper describes the most relevant clinical progress of strategies for the combination of immunotherapy with standard treatment modalities in HER2-positive breast cancer including chemotherapy, targeted therapy, and radiotherapy.

Plasma CCL5 promotes EMT-medicated epirubicin-resistance in locally advanced breast cancer

Neoadjuvant chemotherapy (NCT) is the standard treatment for locally advanced breast cancer (LABC). Pathological complete response (pCR) is commonly used as a valid predictor of NCT long-term outcomes. Blood-based tumor biomarkers have the potential to predict response to NCT at early stage non-invasively. We believed plasma CCL5 could be a potential marker to predict NCT of LABC. Its efficiency and possible mechanism was studied in this work. Human Cytokine Antibody Microarray was applied to screen different cytokine concentration in plasma between low histological regression (Low-R) and high histological regression (High-R) patients. LABC patients were divided into two groups according to pathological reactivity. The concentration of plasma CCL5 in different groups was determined by ELISA analysis. CCK8 assay was performed to analyze epirubicin susceptibility of breast cancer cells. Transwell assay was performed to determine the effect of CCL5 on breast cancer cells' migration and invasion. qRT-PCR and western blot were used to verify the EMT (epithelial-mesenchymal transition) markers in CCL5-treated and epirubicin-treated breast cancer cells. The concentration of plasma CCL5 of Low-R group was higher than High-R group before NCT. The plasma levels of CCL5 were significantly reduced after NCT in the group of high histological regression (High-R). Epirubicin susceptibility decreased in the breast cancer cells treated by recombinant CCL5. Migration and invasion were significantly enhanced in breast cancer cells treated by recombinant CCL5. E-cadherin expression was decreased whereas vimentin increased significantly in CCL5-treated breast cancer cells. The phosphorylation of ezrin in Y-567 and its downstream protein cortactin increased significantly in CCL5-treated breast cancer cells. Plasma CCL5 level could be a promised candidate to predict chemotherapy response of breast cancer. Plasma CCL5 plays an important role in EMT process of breast cancer.

A pilot study of durvalumab and tremelimumab and immunogenomic dynamics in metastatic breast cancer

Immune checkpoint inhibitors produce modest responses in metastatic breast cancer, however, combination approaches may improve responses. A single arm pilot study was designed to determine the overall response rate (ORR) of durvalumab and tremelimumab, and evaluate immunogenomic dynamics in metastatic endocrine receptor (ER) positive or triple negative breast cancer (TNBC). Simon two-stage design indicated at least four responses from the first 18 patients were needed to proceed with the second stage. T-cell receptor (TCR) sequencing and immune-gene expression profiling were conducted at baseline and two months, whole exome sequencing was conducted at baseline. Eighteen evaluable patients were accrued (11 ER-positive; seven TNBC). Only three patients had a response (ORR = 17%), thus the study did not proceed to the second stage. Responses were only observed in patients with TNBC (ORR = 43%). Responders versus non-responders had upregulation of CD8, granzyme A, and perforin 1 gene expression, and higher mutational and neoantigen burden. Patients with TNBC had an oligoclonal shift of the most abundant TCR-beta clonotypes compared to those with ER-positive disease, p = 0.004. We conclude responses are low in unselected metastatic breast cancer, however, higher rates of clinical benefit were observed in TNBC. Immunogenomic dynamics may help identify phenotypes most likely to respond to immunotherapy.

Treating breast cancer with cell-based approaches: an overview

INTRODUCTION

Breast cancer is the most common malignancy in women. Despite there being considerable progress in the treatment of this disease, metastatic dissemination is still considered an incurable condition at the present time, causing 500,000 deaths worldwide every year. Although most of the research efforts have been focused on pharmacological approaches, over the last three decades, the use of bone marrow and peripheral blood-derived cell therapy approaches have been attempted and developed. Areas covered: This review will briefly address cell therapy for breast cancer, including autologous stem cell transplantations for overcoming the myelosuppressive effects of high-dose chemotherapy, allogeneic stem cell transplants and adoptive immunotherapy using bone-marrow derived T-cells. Expert opinion: The treatment of breast cancer using bone marrow or peripheral-blood derived cells has evolved from a supportive care approach to allow dose escalation of conventional chemotherapy to a therapeutic strategy aimed at eliciting immune cell mediated anticancer immunity. This latter principle has led to the development of adoptive immunotherapies, either with 'natural' or genetically engineered effectors, which are being intensively investigated for their great potential against several solid tumors, including breast cancer.