Antiresorptive agents' bone-protective and adjuvant effects in postmenopausal women with early breast cancer

RANK is a poor prognosis marker and a therapeutic target in ER-negative postmenopausal breast cancer

Despite strong preclinical data, the therapeutic benefit of the RANKL inhibitor, denosumab, in breast cancer patients, beyond the bone, is unclear. Aiming to select patients who may benefit from denosumab, we hereby analyzed RANK and RANKL protein expression in more than 2,000 breast tumors (777 estrogen receptor-negative, ER- ) from four independent cohorts. RANK protein expression was more frequent in ER- tumors, where it associated with poor outcome and poor response to chemotherapy. In ER- breast cancer patient-derived orthoxenografts (PDXs), RANKL inhibition reduced tumor cell proliferation and stemness, regulated tumor immunity and metabolism, and improved response to chemotherapy. Intriguingly, tumor RANK protein expression associated with poor prognosis in postmenopausal breast cancer patients, activation of NFKB signaling, and modulation of immune and metabolic pathways, suggesting that RANK signaling increases after menopause. Our results demonstrate that RANK protein expression is an independent biomarker of poor prognosis in postmenopausal and ER- breast cancer patients and support the therapeutic benefit of RANK pathway inhibitors, such as denosumab, in breast cancer patients with RANK+ ER- tumors after menopause.

Therapeutic Options in the Management of Aromatase Inhibitor-Associated Bone Loss

BACKGROUND

Breast cancer is the most commonly occurring cancer in women worldwide. Early breast cancer is a kind of invasive neoplasm that has not proliferated beyond the breast or the axillary lymph nodes. Current therapeutic strategies for breast cancer mainly include local therapies such as surgery or radiotherapy and systemic therapies like chemotherapy, endocrine, and targeted therapy.Nowadays, the adjuvant treatment for hormone receptor-positive early breast cancer in postmenopausal women remains the main effective systemic therapy which can improve disease-free survival and overall survival; it involves several endocrine treatment regimens including selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs), or a combination of them. AIs have been shown to be more effective in preventing recurrence in postmenopausal women with early breast cancer when compared with tamoxifen, thus representing the standard of care for adjuvant endocrine therapy. Although AIs are usually well-tolerated, they can have some side effects. Apart from the appearance of arthralgias or myalgias and cardiovascular events, AI therapies, reducing already low endogenous postmenopausal estradiol levels, cause increased bone loss and increase fracture risk in postmenopausal women.

OBJECTIVES

To evaluate the therapeutic options in the management of aromatase inhibitor-associated bone loss (AIBL).

METHODS

We reviewed the current literature dealing with different therapeutic options in the treatment of AIBL.

RESULTS

Clinical practice guidelines recommend a careful evaluation of skeletal health in all women with breast cancer before AI therapy initiation. Adequate calcium and vitamin D intake have also been suggested. Pharmacological attempts to minimize AI-related bone loss have focused on the use of antiresorptive agents, such as bisphosphonates and denosumab, to protect bone integrity and reduce the risk of fractures. Furthermore, clinical trials have shown that by making the bone microenvironment less susceptible to breast cancer metastasis, these drugs are able to increase disease-free survival.

CONCLUSIONS

AI, thatare the pillar of the systemic treatment for patients with hormone receptor-positive breast cancer, are associated with different side effects, and in particular osteoporosis and fractures. Both bisphosphonates and denosumab are able to prevent this negative effect.

Vertebral Fractures After Denosumab Discontinuation in Breast Cancer Survivors: A Single Institution Experience

Background: Denosumab is approved to prevent fragility fractures in patients with osteoporosis at high risk for fracture and to prevent bone loss in patients with breast and prostate cancer who receive endocrine therapy. The antiresorptive effect of denosumab rapidly dissipates when it is delayed or discontinued, but the risk for, and incidence of, multiple clinical vertebral fractures in patients with breast cancer after stopping denosumab is currently unclear. Question/Purposes: We sought to identify the incidence of clinical vertebral fractures in patients with breast cancer who received at least 2 doses of denosumab (60 mg) and then discontinued the medication. Methods: We conducted a retrospective chart review to identify patients with a history of breast cancer who were treated with denosumab between June 1, 2010, and July 18, 2018, at Memorial Sloan Kettering Cancer Center. We identified 335 postmenopausal women and 1 man with nonmetastatic breast cancer who received their final denosumab injection at least 6.5 months earlier. Data recorded included baseline bone density and the incidence of vertebral fractures after denosumab discontinuation. Results: The median age of patients was 62 years. Patients received between 2 and 13 denosumab doses before drug discontinuation. Most of the patients (310; 92.3%) were also treated with aromatase inhibitors. Of the 194 patients with baseline bone density data, 50 (25.8%) had normal bone density, 97 (50.0%) had osteopenia, and 47 (24.2%) had osteoporosis. The median follow-up duration from the last denosumab dose was 18.5 months. We identified 1 case of spontaneous vertebral fractures after denosumab stoppage. We found no cases of osteonecrosis of the jaw or atypical femur fracture. Most of the patients (88%) had a gap in denosumab dosing. Conclusions: Clinicians treating patients with breast cancer-especially those continuing to take aromatase inhibitors-should be aware of the possible risks of delaying doses of or discontinuing denosumab and should educate their patients accordingly. Prospective studies are needed to fully evaluate the risks of stopping or delaying denosumab.

Managing Menopausal Symptoms in Young Women With Breast Cancer: When Medicine Is Not All. The Take Care Project

In the last decade, endocrine therapy strategies in perimenopausal women with hormone-responsive early breast cancer (BC) have changed and now ovarian function suppression (OFS) is recommended for the majority of patients. Side effects of OFS mimic menopausal symptoms, including hot flushes, sweats, weight gain, and sexual dysfunction, which may negatively impact quality of life (QoL). Aims of the Take Care Project are the education of physicians and patients to have all the information (medical and nonmedical) they need to manage menopausal symptoms by distributing educational materials useful to face menopause. Four different areas have been identified by surveys conducted among physicians and young patients: for each area, interventions and tools have been elaborated by a doctor and nonphysician professionals of these identified areas, to offer the widest information available. Clinical and practical suggestions have been provided. Based on the evidence given, we strongly suggest setting up a multidisciplinary team for the treatment planning of young patients with BC, which could help patients to face and manage their new menopause condition. The reduction of side effects and the improvement in QoL should be the best ally to treat young patients with BC.

Pharmacology of bisphosphonates

The biological effects of the bisphosphonates (BPs) as inhibitors of calcification and bone resorption were first described in the late 1960s. In the 50 years that have elapsed since then, the BPs have become the leading drugs for the treatment of skeletal disorders characterized by increased bone resorption, including Paget's disease of bone, bone metastases, multiple myeloma, osteoporosis and several childhood inherited disorders. The discovery and development of the BPs as a major class of drugs for the treatment of bone diseases is a paradigm for the successful journey from "bench to bedside and back again". Several of the leading BPs achieved "blockbuster" status as branded drugs. However, these BPs have now come to the end of their patent life, making them highly affordable. The opportunity for new clinical applications for BPs also exists in other areas of medicine such as ageing, cardiovascular disease and radiation protection. Their use as inexpensive generic medicines is therefore likely to continue for many years to come. Fifty years of research into the pharmacology of bisphosphonates have led to a fairly good understanding about how these drugs work and how they can be used safely in patients with metabolic bone diseases. However, while we seemingly know much about these drugs, a number of key aspects related to BP distribution and action remain incompletely understood. This review summarizes the existing knowledge of the (pre)clinical and translational pharmacology of BPs, and highlights areas in which understanding is lacking.

Antiresorptive agents' bone-protective and adjuvant effects in postmenopausal women with early breast cancer

Potent antiresorptive drugs (bisphosphonate and denosumab) are often used to protect bone health in postmenopausal breast cancer patients. In addition, clinical trials have shown that these drugs increase disease-free survival, though the mechanism of adjuvant benefit is largely unknown. Here we review the bone health and adjuvant data for both classes of antiresorptive drugs and highlight differences in their pharmacology. Inhibition of bone resorption is vitally important to protect against osteoporotic fractures, and may also contribute to adjuvant survival benefits by making the bone microenvironment less amenable to breast cancer metastasis. After a course of therapy, stoppage of bisphosphonates yields a persistent antiresorptive effect, whereas discontinuation of denosumab causes a rebound increase in bone resorption markers and a loss of bone mineral density to baseline levels. Whether the potential adjuvant benefits of denosumab are also rapidly lost after drug discontinuation deserves further investigation.