Zoledronic Acid for the treatment and prevention of primary and secondary osteoporosis

Challenges of Differential Diagnosis Between Primary Hyperparathyroidism and Bone Metastases of Breast Cancer

Breast cancer might be complicated by distant metastases accompanied by hypercalcemia, but hyperparathyroidism is not commonly considered in the differential diagnosis. We present a case of 38 years old female patient who was diagnosed with ductal breast carcinoma. Eight months after the initial diagnosis the patient was diagnosed with distant bone metastases. However, this diagnosis was reconsidered at follow up, because we identified elevation of PTH 137.2 pg/ml, Ca²⁺ 1.19 mmol/l, albumin corrected calcium 2.42 mmol/l, 25(OH)D 39.4 nmol/l, indicating hyperparathyroidism. Scintigraphy with 99mTC-sestamibi confirmed parathyroid adenoma. Postoperative histopathology confirmed 1.2 g chief-cell PTA. Two months after the operation both PTH and Ca²⁺ levels were within the normal ranges. This study emphasizes the importance of considering possible hyperparathyroidism in patients with breast cancer and hypercalcemia. Routine evaluation of PTH is considered as a reasonable test in patients with breast cancer accompanied by bone lesions.

Humanized bone facilitates prostate cancer metastasis and recapitulates therapeutic effects of zoledronic acid in vivo

Advanced prostate cancer (PCa) is known for its high prevalence to metastasize to bone, at which point it is considered incurable. Despite significant effort, there is no animal model capable of recapitulating the complexity of PCa bone metastasis. The humanized mouse model for PCa bone metastasis used in this study aims to provide a platform for the assessment of new drugs by recapitulating the human-human cell interactions relevant for disease development and progression. The humanized tissue-engineered bone construct (hTEBC) was created within NOD-scid IL2rgnull (NSG) mice and was used for the study of experimental PC3-Luc bone metastases. It was confirmed that PC3-Luc cells preferentially grew in the hTEBC compared with murine bone. The translational potential of the humanized mouse model for PCa bone metastasis was evaluated with two clinically approved osteoprotective therapies, the non-species-specific bisphosphonate zoledronic acid (ZA) or the human-specific antibody Denosumab, both targeting Receptor Activator of Nuclear Factor Kappa-Β Ligand. ZA, but not Denosumab, significantly decreased metastases in hTEBCs, but not murine femora. These results highlight the importance of humanized models for the preclinical research on PCa bone metastasis and indicate the potential of the bioengineered mouse model to closely mimic the metastatic cascade of PCa cells to human bone. Eventually, it will enable the development of new effective antimetastatic treatments.

Odanacatib: An Emerging Novel Treatment Alternative for Postmenopausal Osteoporosis

Odanacatib represents a novel treatment option in the approach of postmenopausal women. Postmenopausal women with osteoporosis experience a disturbance in bone remodeling wherein bone resorption exceeds bone formation. Cathepsin K is a lysosomal cysteine protease found primarily in osteoclasts that plays a major role in the breakdown of bone via its collagenase properties. Targeting a new area of pathophysiology, odanacatib inhibits cathepsin K to reduce bone resorption while preserving bone formation. Phase II and III trials have shown efficacy in increasing bone mineral density in the target treatment group. Overall, safety studies have found odanacatib to be well-tolerated and comparable to placebo; however, some imbalances in adverse events have been observed in the Phase III trials. Current and future studies will analyze the long-term ability of odanacatib in preventing bone fracture.

Efficacy of zoledronic acid in treatment of osteoporosis in men and women-a meta-analysis

BACKGROUND

Osteoporosis is a significant cause of morbidity and mortality in the elderly and an important public health issue. Bisphosphonates are the primary treatment options for osteoporosis. The oral administration of bisphosphonates may result in poor patient compliance and thence reduced treatment efficacy. Intravenously administered bisphosphonates may therefore show better treatment efficacy. We have carried out a meta-analysis to evaluate the efficacy of zoledronic acid treatment for osteoporosis in both men and women with either vertebral or non-vertebral fracture.

MATERIAL AND METHODS

Randomized controlled trials with zoledronic acid treatment for osteoporosis were retrieved from PubMed, EMBASE and clinicaltrials.gov. The risk ratio with 95% confidence interval (RR, 95% CI) was calculated to evaluate the effect of zoledronic acid treatment on incidence of fracture. Data on changes in bone mineral density (BMD) following zoledronic acid (ZOL) treatment was also extracted. STATA software was used for all the statistical analyses.

RESULTS

Significant reduction in the incidence of both vertebral and nonvertebral fracture was observed following ZOL treatment, as seen from the values for RR with 95% CI (RR 0.24 and 95% CI 0.15 to 0.40 for vertebral fractures; RR 0.76 and 95% CI 0.67 to 0.86 for nonvertebral fractures). BMD was also seen to be increased after ZOL treatment.

CONCLUSION

Ourmeta-analysis showed that zoledronic acid was effective in reducing the incidence of vertebral fractures as well as nonvertebral fractures, including hip fractures. Significant increase in bone mineral density (BMD) was also observed in patients administered ZOL as compared to placebo.

Effects of ageing, prolonged estrogen deficiency and zoledronate on bone tissue mineral distribution

The quantity and distribution of bone tissue mineral are key determinants of bone strength. Recent research revealed altered mineral distribution within sheep femora following estrogen deficiency. Rapid increases in bone remodeling occur at the onset of estrogen deficiency and abate over time. Therefore, altered tissue mineralization might be a transient characteristic of osteoporosis. Bisphosphonates reduce fracture incidence by 40-60% but increases in bone mineral density are insufficient to explain such changes. In this study the hypotheses that bone tissue mineralization is altered over prolonged estrogen depletion and bisphosphonate treatment were tested. Quantitative backscattered imaging (qBEI) was used to quantify bone mineral density distribution (BMDD) parameters (mean, FWHM) in trabeculae from the proximal femora of an ovariectomized sheep model that underwent estrogen deficiency for 31 months, an ovariectomized group administered with Zoledronic acid and age-matched controls. To assess the effects of normal ageing and prolonged estrogen deficiency, data were compared to BMDD data from sheep that were estrogen deficient for 12 months and age-matched controls. This study reports that normal ageing increases mean mineralization and mineral heterogeneity at a trabecular level. In contrast, prolonged estrogen deficiency leads to significantly decreased mean mineralization and further exacerbates increases in mineral heterogeneity. Interestingly, ZOL treatment of OVX sheep significantly reduced tissue mineral variability, both at a trabecular level and between femoral regions. Together, these findings indicate that ZOL treatment acts to reverse the increased mineral heterogeneity occurring during estrogen deficiency, which may contribute to its capacity to reduce osteoporotic fractures.

Osteoporosis - a current view of pharmacological prevention and treatment

Postmenopausal osteoporosis is the most common bone disease, associated with low bone mineral density (BMD) and pathological fractures which lead to significant morbidity. It is defined clinically by a BMD of 2.5 standard deviations or more below the young female adult mean (T-score =−2.5). Osteoporosis was a huge global problem both socially and economically – in the UK alone, in 2011 £6 million per day was spent on treatment and social care of the 230,000 osteoporotic fracture patients – and therefore viable preventative and therapeutic approaches are key to managing this problem within the aging population of today. One of the main issues surrounding the potential of osteoporosis management is diagnosing patients at risk before they develop a fracture. We discuss the current and future possibilities for identifying susceptible patients, from fracture risk assessment to shape modeling and in relation to the high heritability of osteoporosis now that a plethora of genes have been associated with low BMD and osteoporotic fracture. This review highlights the current therapeutics in clinical use (including bisphosphonates, anti-RANKL [receptor activator of NF-κB ligand], intermittent low dose parathyroid hormone, and strontium ranelate) and some of those in development (anti-sclerostin antibodies and cathepsin K inhibitors). By highlighting the intimate relationship between the activities of bone forming (osteoblasts) and bone-resorbing (osteoclasts) cells, we include an overview and comparison of the molecular mechanisms exploited in each therapy.

Bisphosphonates for post-menopausal osteoporosis: are they all the same?

The primary goal of treatment for post-menopausal osteoporosis (PMO) is reduction in fracture risk. Therefore, clinicians must recommend therapies that are safe and have proven anti-fracture efficacy. Bisphosphonates have long been established as first-line therapy for osteoporosis and several of these drugs significantly reduce osteoporotic fracture risk. However, choosing among different bisphosphonates can represent a difficult clinical decision. This review outlines the pharmacology of various bisphosphonates, discusses how their pharmacological characteristics affect their efficacy, and summarizes clinical safety and efficacy data. Clinical trial data and the opinions of expert bodies suggest that alendronate, risedronate, ibandronate and zoledronic acid all provide fracture protection for patients with PMO. However, there are differences among these agents. For example, all four agents have demonstrated efficacy in preventing vertebral fractures, but only zoledronic acid and risedronate significantly reduce non-vertebral fracture risk in pivotal trials. Moreover, reduction in hip fracture risk has only been established for alendronate, risedronate and zoledronic acid. Current data suggest that ibandronate and zoledronic acid have the most persistent antifracture effect. Bisphosphonates have been associated with a number of side effects, the evidence for which is summarized in this review. The most pertinent of these when choosing a bisphosphonate for a particular patient are the well-documented associations between gastrointestinal adverse events and oral administration, and between acute phase reactions and intravenous administration. Ultimately, selection of a specific bisphosphonate for treatment of PMO should be based on efficacy, risk profile, cost-effectiveness and patient preference.