The Clinical Benefits of Antiresorptive Agents in Patients with Primary Breast Cancer Receiving Adjuvant Endocrine Therapy: A Systematic Review with Pairwise and Network Meta-analysis

CONTEXT

Clinical trials have investigated the role of antiresorptive agents, including bisphosphonates and denosumab, in patients with primary breast cancer receiving adjuvant endocrine therapy, aiming for better bone protection and/or improving survival.

OBJECTIVE

To summarize the clinical effects of antiresorptive agents in patients with early breast cancer receiving endocrine therapy.

METHODS

We systematically reviewed and synthesized the clinical benefits and harms of antiresorptive agents in patients with early breast cancer receiving endocrine therapy by calculating the risk ratios (RRs).

RESULTS

In the pooled meta-analysis, antiresorptive agents had significant clinical benefits on disease recurrence (RR 0.78, 95% CI 0.67-0.90) and locoregional recurrence (RR 0.69, 95% CI 0.49-0.95) in patients with breast cancer receiving endocrine therapy. Early use of antiresorptive agents has a beneficial effect on secondary endocrine therapy resistance instead of primary resistance. Safety analysis revealed that potential risk for osteonecrosis of the jaw (ONJ, RR 3.29, 95% CI 1.12-9.68) with antiresorptive agents; however, there is an insignificant difference in arthralgia. The subgroup analyses revealed that intervention with bisphosphonates might have profound clinical benefits, but also increased the occurrence of ONJ. A network meta-analysis further supported the clinical effects of early antiresorptive agent use compared with delayed use or placebo.

CONCLUSION

Using antiresorptive agents early in patients with breast cancer receiving adjuvant endocrine therapy may provide additional benefits in risk reduction of recurrence, but there is a potential risk of ONJ.

Retrospective Analysis of Treatment Outcomes of Maxillary Sinusitis Associated with Medication-Related Osteonecrosis of the Jaw

Although maxillary sinusitis often occurs in patients with medication-related osteonecrosis of the jaw (MRONJ) of the upper jaw, there have been few reports on the treatment and outcomes for maxillary sinusitis associated with maxillary MRONJ. This study aimed to retrospectively investigate the treatment outcomes of maxillary sinusitis in patients with MRONJ of the upper jaw. There were 34 patients diagnosed with maxillary MRONJ and sinusitis by preoperative computed tomography who underwent surgery in our institution between January 2011 and December 2019. Age, sex, primary disease, stage of MRONJ, class and administration period of an antiresorptive agent, corticosteroid administration, preoperative leukocyte count and serum albumin level, periosteal reaction, sinusitis grade, maxillary sinus surgical procedure, and treatment outcomes of MRONJ and sinusitis were examined. There were 7 male and 27 female patients (average age, 74.7 years). Complete healing of MRONJ was obtained in 29 of 34 patients (85.3%). Maxillary sinusitis resolved or improved in 21 patients (61.8%) but did not change or worsen in 13 patients (38.2%). We found that complete resection of necrotic bone with intraoperative irrigation of the maxillary sinus may provide good treatment outcomes for maxillary sinusitis associated with MRONJ, although our findings were not statistically significant owing to the small number of patients.

Antiresorptive Agents and Anti-Angiogenesis Drugs in the Development of Osteonecrosis of the Jaw

Medication-related osteonecrosis of the jaw (MRONJ) is a condition of exposed bone in the maxillofacial region, which occurs among subjects treated with antiresorptive agents or anti-angiogenesis drugs, despite the lack of a history of head or neck radiation treatment. Although there are still many points to be clarified about the mechanism of MRONJ, it is possible to hypothesize a common pathogenetic mechanism for two different classes of drugs: antiresorptive and anti-angiogenetic drugs. These drugs can inhibit angiogenesis by interfering with endothelial cell proliferation and survival, leading to loss of blood vessels and avascular necrosis. This hypothesis could be of immediate translational interest. Targeting the anti-angiogenetic effect of the antiresorptive agents could provide a new possibility for the prevention of treatment of MRONJ.

Prospective comparison of the therapeutic effect of teriparatide with that of combined vertebroplasty with antiresorptive agents for the treatment of new-onset adjacent vertebral compression fracture after percutaneous vertebroplasty

Most post-vertebroplasty new-onset adjacent vertebral compression fractures (VCFs) occur within 2-3 months, and antiresorptive agents do not significantly reduce the risk of their occurrence. In opposite mechanism, teriparatide directly stimulates bone formation and improves bone strength and quality faster. The therapeutic effect of teriparatide is better than that of vertebroplasty combined with an antiresorptive treatment and is a potentially useful therapy for new-onset adjacent VCFs after vertebroplasty.

INTRODUCTION

Following vertebroplasty, patients are at increased risk of new-onset adjacent-level VCFs. The therapeutic effect of antiresorptive agents is too slow, and they are associated with the risk of new VCFs. Teriparatide markedly increases bone formation and strength and reduces the incidence of new-onset VCFs. This prospective cohort study compared the therapeutic effects of teriparatide with those of combined vertebroplasty and an anti-resorber for treating new-onset adjacent VCFs after vertebroplasty.

METHODS

Fifty patients with adjacent VCFs were randomly assigned to two groups: teriparatide only (group A) and additional vertebroplasty combined with an antiresorptive agent (group B). Relevant clinical data of the two groups were prospectively compared.

RESULTS

The 22 patients in group A were at higher risk of new VCFs than those in group B (22 patients); they were older and had more pre-existing fractures (p < 0.05). Patients treated with teriparatide had a significantly lower incidence of new-onset VCFs (odds ratio = 0.21; 95% confidence interval, 0.02-2.10). Teriparatide-mediated VCF reduction was 78.57%, which was markedly better than that of group B. The teriparatide group had a significant decrease in the visual analog scale and an increase in the Japanese Orthopedic Association low back pain score after 6 months of treatment (p < 0.05). The increase in lumbar spine BMD was marked in the teriparatide group (21.70% vs. 6.87%) after an 18-month treatment.

CONCLUSIONS

Treatment of post-vertebroplasty adjacent VCFs with teriparatide (no new vertebroplasty) was more effective than that of repeated vertebroplasties combined with an anti-resorber.

Current and emerging therapies for the treatment of osteoporosis

Osteoporosis represents a weakening of bone tissue due to an imbalance in the dynamic processes of bone formation and bone resorption that are continually ongoing within bone tissue. Most currently available osteoporosis therapies are antiresorptive agents. Over the past decade, bisphosphonates, notably alendronate and risedronate, have become the dominant agents with newer bisphosphonates such as ibandronate and zoledronic acid following a trend of less frequent dosing regimens. Synthetic estrogen receptor modulators (SERMs) continue to be developed as drugs that maintain the bone-protective effects of estrogen while avoiding its associated adverse side effects. Currently available agents of this class include raloxifene, the only SERM available in the United States (US), and lasofoxifene and bazedoxifene, available in Europe. Calcitonin, usually administered as a nasal spray, completes the list of currently approved antiresorptive agents, while parathyroid hormone analogs represent the only anabolic agents currently approved in both the US and Europe. Strontium ranelate is an additional agent available in Europe but not the US that has both anabolic and antiresorptive activity. New agents expected to further expand therapeutic options include denosumab, a monoclonal antibody inhibitor of the resorptive enzyme cathepsin K, which is in the final stages of Food and Drug Administration approval. Other agents in preclinical development include those targeting specific molecules of the Wnt/β-catenin pathway involved in stimulating bone formation by osteoblast cells. This review discusses the use of currently available agents as well as highlighting emerging agents expected to bring significant changes to the approach to osteoporosis therapy in the near future.