Adding Ovarian Suppression to Tamoxifen for Premenopausal Women With Hormone Receptor-Positive Breast Cancer After Chemotherapy: An 8-Year Follow-Up of the ASTRRA Trial

Inhibition of MFN1 restores tamoxifen-induced apoptosis in resistant cells by disrupting aberrant mitochondrial fusion dynamics

Tamoxifen (TAM) resistance presents a major clinical obstacle in the management of estrogen-sensitive breast cancer, highlighting the need to understand the underlying mechanisms and potential therapeutic approaches. We showed that dysregulated mitochondrial dynamics were involved in TAM resistance by protecting against mitochondrial apoptosis. The dysregulated mitochondrial dynamics were associated with increased mitochondrial fusion and decreased fission, thus preventing the release of mitochondrial cytochrome c to the cytoplasm following TAM treatment. Dynamin-related GTPase protein mitofusin 1 (MFN1), which promotes fusion, was upregulated in TAM-resistant cells, and high MFN1 expression indicated a poor prognosis in TAM-treated patients. Mitochondrial translocation of MFN1 and interaction between MFN1 and mitofusin 2 (MFN2) were enhanced to promote mitochondrial outer membrane fusion. The interaction of MFN1 and cristae-shaping protein optic atrophy 1 (OPA1) and OPA1 oligomerization were reduced due to augmented OPA1 proteolytic cleavage, and their apoptosis-promoting function was reduced due to cristae remodeling. Furthermore, the interaction of MFN1 and BAK were increased, which restrained BAK activation following TAM treatment. Knockdown or pharmacological inhibition of MFN1 blocked mitochondrial fusion, restored BAK oligomerization and cytochrome c release, and amplified activation of caspase-3/9, thus sensitizing resistant cells to apoptosis and facilitating the therapeutic effects of TAM both in vivo and in vitro. Conversely, overexpression of MFN1 alleviated TAM-induced mitochondrial apoptosis and promoted TAM resistance in sensitive cells. These results revealed that dysregulated mitochondrial dynamics contributes to the development of TAM resistance, suggesting that targeting MFN1-mediated mitochondrial fusion is a promising strategy to circumvent TAM resistance.

Ovarian Suppression: Early Menopause and Late Effects

OPINION STATEMENT

Around 90% of breast tumours are diagnosed in the early stage, with approximately 70% being hormone receptor-positive. The cornerstone of adjuvant therapy for early-stage hormone receptor-positive breast cancer is endocrine therapy, tailored according to disease stage, biological characteristics of the tumour, patient's comorbidities, preferences and age. In premenopausal patients with hormone receptor-positive breast cancer, ovarian function suppression is a key component of the adjuvant endocrine treatment in combination with an aromatase inhibitor or tamoxifen. Moreover, it can be used during chemotherapy as a standard strategy for ovarian function preservation in all breast cancer subtypes. In the metastatic setting, ovarian function suppression should be used in all premenopausal patients with hormone receptor-positive breast cancer to achieve a post-menopausal status. Despite its efficacy, ovarian function suppression may lead to several side effects that can have a major negative impact on patients' quality of life if not properly managed (e.g. hot flashes, depression, cognitive impairment, osteoporosis, sexual dysfunction, weight gain). A deep knowledge of the side effects of ovarian function suppression is necessary for clinicians. A correct counselling in this regard and proactive management should be considered a fundamental part of survivorship care to improve treatment adherence and patients' quality of life.

Dynamic interplay of nuclear receptors in tumor cell plasticity and drug resistance: Shifting gears in malignant transformations and applications in cancer therapeutics

Recent advances have brought forth the complex interplay between tumor cell plasticity and its consequential impact on drug resistance and tumor recurrence, both of which are critical determinants of neoplastic progression and therapeutic efficacy. Various forms of tumor cell plasticity, instrumental in facilitating neoplastic cells to develop drug resistance, include epithelial-mesenchymal transition (EMT) alternatively termed epithelial-mesenchymal plasticity, the acquisition of cancer stem cell (CSC) attributes, and transdifferentiation into diverse cell lineages. Nuclear receptors (NRs) are a superfamily of transcription factors (TFs) that play an essential role in regulating a multitude of cellular processes, including cell proliferation, differentiation, and apoptosis. NRs have been implicated to play a critical role in modulating gene expression associated with tumor cell plasticity and drug resistance. This review aims to provide a comprehensive overview of the current understanding of how NRs regulate these key aspects of cancer biology. We discuss the diverse mechanisms through which NRs influence tumor cell plasticity, including EMT, stemness, and metastasis. Further, we explore the intricate relationship between NRs and drug resistance, highlighting the impact of NR signaling on chemotherapy, radiotherapy and targeted therapies. We also discuss the emerging therapeutic strategies targeting NRs to overcome tumor cell plasticity and drug resistance. This review also provides valuable insights into the current clinical trials that involve agonists or antagonists of NRs modulating various aspects of tumor cell plasticity, thereby delineating the potential of NRs as therapeutic targets for improved cancer treatment outcomes.

Updates in the treatment of HR+HER2- breast cancer

PURPOSE OF REVIEW

Breast cancer (BC) is the most common cancer among women in the United States and the second leading cause of cancer death. BC research, diagnostics, drug development, and expansion of therapies for novel indications advances so rapidly that BC treatment standards change month-by-month. Herein we discuss notable advancements in the past year for hormone receptor positive (HR+) HER2 negative (HER2-) BC.

RECENT FINDINGS

Radiolabeled estradiol imaging and circulating tumor DNA (ctDNA) have changed our approach to metastatic BC (mBC) detection. Amongst an abundance of therapy options, treatment de-escalation to avoid toxicities is a priority. Promising results with CDK4/6 inhibitors in the curative setting have been demonstrated even as we await final data for use in the metastatic setting. Several novel endocrine therapies are expected to gain FDA-approval in the near future. Antibody-drug conjugates have expanded from other mBC types to HR+HER2- mBC. The PROMISE trial helped define disease recurrence outcomes for premenopausal women seeking pregnancy.

SUMMARY

The diagnostic and treatment landscape for HR+HER2- BC continues to rapidly evolve on multiple fronts.

Therapeutic evolution in HR+/HER2- breast cancer: from targeted therapy to endocrine therapy

Breast cancer, a complex and varied disease, has four distinct subtypes based on estrogen receptor and human epidermal growth factor receptor 2 (HER2) levels, among which a significant subtype known as HR+/HER2-breast cancer that has spurred numerous research. The prevalence of breast cancer and breast cancer-related death are the most serious threats to women's health worldwide. Current progress in treatment strategies for HR+/HER2-breast cancer encompasses targeted therapy, endocrine therapy, genomic immunotherapy, and supplementing traditional methods like surgical resection and radiotherapy. This review article summarizes the current epidemiology of HR+/HER2-breast cancer, introduces the classification of HR+/HER2-breast cancer and the commonly used treatment methods. The mechanisms of action of various drugs, including targeted therapy drugs and endocrine hormone therapy drugs, and their potential synergistic effects are deeply discussed. In addition, clinical trials of these drugs that have been completed or are still in progress are included.

Selection of appropriate biomarkers to monitor effectiveness of ovarian function suppression in pre-menopausal patients with ER+ breast cancer

Use of gonadotropin-releasing hormone (GnRH) agonists has been widely adopted to provide reversible ovarian function suppression for pre-menopausal breast cancer patients who are also receiving aromatase inhibitor or tamoxifen therapy based on results of 25 randomized trials representing almost 15,000 women demonstrating a survival benefit with this approach. Past clinical trials designed to establish the efficacy of GnRH agonists have monitored testosterone in the prostate cancer setting and estradiol in the breast cancer setting. We explore the merits of various biomarkers including estradiol, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) and their utility for informing GnRH agonist treatment decisions in breast cancer. Estradiol remains our biomarker of choice in ensuring adequate ovarian function suppression with GnRH agonist therapy among pre-menopausal women with breast cancer. We recommend future trials to continue to focus on estradiol levels as the primary endpoint, as they have in the past.

Tata Memorial Centre Evidence Based Management of Breast cancer

ABSTRACT

The incidence of breast cancer is increasing rapidly in urban India due to the changing lifestyle and exposure to risk factors. Diagnosis at an advanced stage and in younger women are the most concerning issues of breast cancer in India. Lack of awareness and social taboos related to cancer diagnosis make women feel hesitant to seek timely medical advice. As almost half of women develop breast cancer at an age younger than 50 years, breast cancer diagnosis poses a huge financial burden on the household and impacts the entire family. Moreover, inaccessibility, unaffordability, and high out-of-pocket expenditure make this situation grimmer. Women find it difficult to get quality cancer care closer to their homes and end up traveling long distances for seeking treatment. Significant differences in the cancer epidemiology compared to the west make the adoption of western breast cancer management guidelines challenging for Indian women. In this article, we intend to provide a comprehensive review of the management of breast cancer from diagnosis to treatment for both early and advanced stages from the perspective of low-middle-income countries. Starting with a brief introduction to epidemiology and guidelines for diagnostic modalities (imaging and pathology), treatment has been discussed for early breast cancer (EBC), locally advanced, and MBC. In-depth information on loco-regional and systemic therapy has been provided focusing on standard treatment protocols as well as scenarios where treatment can be de-escalated or escalated.