Olaparib in hormone receptor-positive, HER2-negative metastatic breast cancer with a somatic BRCA2 mutation

Real-world data in patients with BRCA mutated breast cancer treated with poly (ADP-ribose) polymerase inhibitors

Breast cancer is the most common type of cancer globally. Hereditary breast cancer accounts for 10% of new cases and 4%-5% of cases are associated to pathogenic variants in BRCA1 or BRCA2 genes. In recent years, poly-adenosine-diphosphate-ribose polymerase inhibitors (PARPi) olaparib and talazoparib have been approved for patients with BRCA-associated, HER2 -negative breast cancer. These drugs have shown positive results in the early and advanced setting with a favourable toxicity profile based on the OlympiAD, OlympiA and EMBRACA phase 3 trials. However, patients included in these randomised trials are highly selected, making toxicity and efficacy in patients encountered in routine clinical care a concern. Since the approval of olaparib and talazoparib for advanced human epidermal growth factor receptor 2-negative (HER2-negative) breast cancer, several phase IIIb-IV trials, expanded access cohorts, and retrospective cohorts have provided information on the efficacy and tolerability of these treatments in patient subgroups underrepresented in the registration trials, such as older adults, patients with poor performance status, and heavily pretreated patients. The aim of this review is to present a critical review of the information regarding the use of PARPi in real-world breast cancer patients.

Calcium Homeostasis in the Development of Resistant Breast Tumors

Cancer is one of the main health problems worldwide. Only in 2020, this disease caused more than 19 million new cases and almost 10 million deaths, with breast cancer being the most diagnosed worldwide. Today, despite recent advances in breast cancer treatment, a significant percentage of patients will either not respond to therapy or will eventually experience lethal progressive disease. Recent studies highlighted the involvement of calcium in the proliferation or evasion of apoptosis in breast carcinoma cells. In this review, we provide an overview of intracellular calcium signaling and breast cancer biology. We also discuss the existing knowledge on how altered calcium homeostasis is implicated in breast cancer development, highlighting the potential utility of Ca2+ as a predictive and prognostic biomarker, as well as its potential for the development of new pharmacological treatments to treat the disease.

Post-CDK 4/6 Inhibitor Therapy: Current Agents and Novel Targets

Front-line therapy for advanced and metastatic hormone receptor positive (HR+), HER2 negative (HER-) advanced or metastatic breast cancer (mBC) is endocrine therapy with a CDK4/6 inhibitor (CDK4/6i). The introduction of CDK4/6i has dramatically improved progression-free survival and, in some cases, overall survival. The optimal sequencing of post-front-line therapy must be personalized to patients' overall health and tumor biology. This paper reviews approved next lines of therapy for mBC and available data on efficacy post-progression on CDK4/6i. Given the success of endocrine front-line therapy, there has been an expansion in therapies under clinical investigation targeting the estrogen receptor in novel ways. There are also clinical trials ongoing attempting to overcome CDK4/6i resistance. This paper will review these drugs under investigation, review efficacy data when possible, and provide descriptions of the adverse events reported.

Molecular perspective on targeted therapy in breast cancer: a review of current status

Breast cancer is categorized at the molecular level according to the status of certain hormone and growth factor receptors, and this classification forms the basis of current diagnosis and treatment. The development of resistance to treatment and recurrence of the disease have led researchers to develop new therapies. In recent years, most of the research in the field of oncology has focused on the development of targeted therapies, which are treatment methods developed directly against molecular abnormalities. Promising advances have been made in clinical trials investigating the effect of these new treatment modalities and their combinations with existing therapeutic treatments in the treatment of breast cancer. Monoclonal antibodies, tyrosine kinase inhibitors, antibody–drug conjugates, PI3K/Akt/mTOR pathway inhibitors, cyclin-dependent kinase 4/6 inhibitors, anti-angiogenic drugs, PARP inhibitors are among the targeted therapies used in breast cancer treatment. In this review, we aim to present a molecular view of recently approved target agents used in breast cancer.

A review of the endocrine resistance in hormone-positive breast cancer

Hormone-positive breast cancer (BC) is a unique heterogeneous disease with a favorable prognosis compared to other types of breast cancer. As tumor biology influences the prognosis and clinical treatment, a deep understanding of how the molecular mechanisms regulate hormone sensitivity or resistance is critical in improving the efficacy and overcoming the endocrine resistance. This article comprehensively reviews the endocrine resistance in hormone-positive BC from a molecular and genetic perspective, encompassing the updated treatment and developing direction. This review includes the mechanisms of hormone resistance, which vary from epigenetic changes, crosstalk between signaling networks, cell cycle aberrance, and even change in the tumor microenvironment (TME) or stem cell. These mechanisms may contribute to treatment resistance. Current targeted therapy for hormone-resistant tumors includes PI3K/AKT/mTOR and cdk4/6 inhibitors. Several relevant pathways, biomarkers, and predictor genes have also been identified. Immunotherapy so far has a relatively less crucial role in hormone-positive than in triple-negative BC. Furthermore, the methodology to identify the PDL1 is not standardized. In a molecule and gene study, next-generation sequencing with circulating tumor DNA (ctDNA) has recently appeared as a sensitive and minimally invasive tool worth investigating.