Romosozumab in patients who experienced an on-study fracture: post hoc analyses of the FRAME and ARCH phase 3 trials

Post hoc analysis of FRAME and ARCH revealed that on-study nonvertebral and vertebral fractures by Month 12 were less common in women initially treated with romosozumab versus placebo or alendronate. Recurrent fracture risk was also lower in romosozumab‑treated patients, and there were no fracture‑related complications. Results support continuing romosozumab treatment post‑fracture.

PURPOSE

Post hoc analysis evaluating efficacy and safety of romosozumab, administered in the immediate post‑fracture period, in the FRAME and ARCH phase 3 trials.

METHODS

In FRAME (NCT01575834) and ARCH (NCT01631214), postmenopausal women with osteoporosis were randomized 1:1 to romosozumab 210 mg monthly or comparator (FRAME, placebo; ARCH, alendronate 70 mg weekly) for 12 months, followed by antiresorptive therapy (FRAME, denosumab; ARCH, alendronate). In patients who experienced on-study nonvertebral or new/worsening vertebral fracture by Month 12, we report the following: fracture and treatment‑emergent adverse event (TEAE) incidence through 36 months, bone mineral density changes (BMD), and romosozumab timing. Due to the sample sizes employed, meaningful statistical comparisons between treatments were not possible.

RESULTS

Incidence of on-study nonvertebral and vertebral fractures by Month 12 was numerically lower in romosozumab- versus comparator-treated patients (FRAME, 1.6% and 0.5% versus 2.1% and 1.6%; ARCH, 3.4% and 3.3% versus 4.6% and 4.9%, respectively). In those who experienced on-study nonvertebral fracture by Month 12, recurrent nonvertebral and subsequent vertebral fracture incidences were numerically lower in patients initially treated with romosozumab versus comparator (FRAME, 3.6% [2/56] and 1.8% [1/56] versus 9.2% [7/76] and 3.9% [3/76]; ARCH, 10.0% [7/70] and 5.7% [4/70] versus 12.6% [12/95] and 8.4% [8/95], respectively). Among those with on-study vertebral fracture by Month 12, recurrent vertebral and subsequent nonvertebral fracture incidences were numerically lower with romosozumab versus comparator (FRAME, 0.0% [0/17] and 0.0% [0/17] versus 11.9% [7/59] and 8.5% [5/59]; ARCH, 9.0% [6/67] and 7.5% [5/67] versus 15.0% [15/100] and 16.0% [16/100], respectively). In patients with fracture by Month 12, no fracture‑related complications were reported in romosozumab-treated patients. BMD gains were numerically greater with romosozumab than comparators.

CONCLUSION

Data suggest support for the efficacy and safety of continuing romosozumab treatment following fracture.

TRIAL REGISTRATIONS

NCT01575834; NCT01631214.

The treatment gap after major osteoporotic fractures in Denmark 2005-2014: a combined analysis including both prescription-based and hospital-administered anti-osteoporosis medications

This study demonstrates a substantial and persistent anti-osteoporosis treatment gap in men and women ≥50 years old who sustained major osteoporotic fracture(s) between 2005 and 2014 in Denmark. This was not substantially reduced by including hospital-administered anti-osteoporosis treatments. Strengthened post-fracture organization of care and secondary fracture prevention is highly needed.

INTRODUCTION

The purpose of this study was to evaluate the Danish anti-osteoporosis treatment gap from 2005 to 2014 in patients sustaining a major osteoporotic fracture (MOF), and to assess the impact of including hospital-administered anti-osteoporosis medications (AOM) on the treatment gap among these patients.

METHODS

In this retrospective, registry-based study, we included men and women aged 50 years or older and living in Denmark, who sustained at least one MOF between 2005 and 2014. We applied a repeated cross-sectional design to generate cohorts of patients sustaining a first MOF, hip, vertebral, humerus, or forearm fracture, respectively, within each calendar year. We evaluated the treatment gap as the proportion of patients within each cohort not receiving treatment with AOM within 1 year of the fracture. Hospital-administered AOM was identified by SKS code.

RESULTS

The treatment gap among MOF patients decreased from 85% in 2005 to 79% in 2014. The gap was smaller among hip and vertebral fracture patients as compared to humerus and forearm fracture patients, and it was smaller in women than in men. The use of hospital-administered AOM was relatively uncommon, with a maximum of 0.9% of MOF patients initiating hospital-administered AOM (in 2012). We observed substantial variations in this proportion between fracture types and gender. Hospital-administered AOM was most commonly used among vertebral fracture patients.

CONCLUSION

A significant treatment gap among patients sustaining a major osteoporotic fracture was present throughout our analysis, and including hospital-administered AOM did not significantly improve the treatment gap assessment. Improved secondary fracture prevention is urgently needed.

A novel economic framework to assess the cost-effectiveness of bone-forming agents in the prevention of fractures in patients with osteoporosis

A novel cost-effectiveness model framework was developed to incorporate the elevated fracture risk associated with a recent fracture and to allow sequential osteoporosis therapies to be evaluated. Treating patients with severe osteoporosis after a recent fracture with a bone-forming agent followed by antiresorptive therapy can be cost-effective compared with antiresorptive therapy alone. Incorporating these novel technical attributes in economic evaluations can support appropriate policy and reimbursement decision-making.

PURPOSE

To develop a cost-effectiveness model accommodating increased fracture risk after a recent fracture and treatment sequencing.

METHODS

A micro-simulation cost-utility model was developed to accommodate both treatment sequencing and increased risk with recent fracture. The risk of fracture was estimated and simulated using the FRAX® algorithms combined with Swedish registry data on imminent fracture relative risk. In the base-case cost-effectiveness analysis, a sequential treatment starting with a bone-forming agent for 12 months followed by an antiresorptive agent for 48 months initiated immediately after a major osteoporotic fracture (MOF) in a 70-year-old woman with a T-score of 2.5 or less was compared to an antiresorptive treatment alone for 60 months. The model was populated with data relevant for a UK population reflecting a personal social service perspective.

RESULTS

The cost per additional quality-adjusted life year (QALY) gained in the base-case setting was estimated at £34,584. Sensitivity analyses revealed the sequential treatment to be cost-saving compared with administering a bone-forming treatment alone. Without simulating an elevated fracture risk immediately after a recent fracture, the cost per QALY changed from £34,584 to £62,184.

CONCLUSION

Incorporating imminent fracture risk in economic evaluations has a significant impact on the cost-effectiveness when evaluating fracture prevention treatments in patients with osteoporosis who sustained a recent fracture. Bone-forming treatment followed by antiresorptive therapy can be cost-effective compared to antiresorptive therapy alone depending on treatment acquisition costs.

Secular trends in the initiation of therapy in secondary fracture prevention in Europe: a multi-national cohort study including data from Denmark, Catalonia, and the United Kingdom

This paper demonstrates a large post-fracture anti-osteoporosis treatment gap in the period 2005 to 2015. The gap was stable in Denmark at around 88-90%, increased in Catalonia from 80 to 88%, and started to increase in the UK towards the end of our study. Improved post-fracture care is needed.

INTRODUCTION

Patients experiencing a fragility fracture are at high risk of subsequent fractures, particularly within the first 2 years after the fracture. Previous studies have demonstrated that only a small proportion of fracture patients initiate therapy with an anti-osteoporotic medication (AOM), despite the proven fracture risk reduction of such therapies. The aim of this paper is to evaluate the changes in this post-fracture treatment gap across three different countries from 2005 to 2015.

METHODS

This analysis, which is part of a multinational cohort study, included men and women, aged 50 years or older, sustaining a first incident fragility fracture. Using routinely collected patient data from three administrative health databases covering Catalonia, Denmark, and the United Kingdom, we estimated the treatment gap as the proportion of patients not treated with AOM within 1 year of their first incident fracture.

RESULTS

A total of 648,369 fracture patients were included. Mean age 70.2-78.9 years; 22.2-31.7% were men. In Denmark, the treatment gap was stable at approximately 88-90% throughout the 2005 to 2015 time period. In Catalonia, the treatment gap increased from 80 to 88%. In the UK, an initially decreasing treatment gap-though never smaller than 63%-was replaced by an increasing gap towards the end of our study. The gap was more pronounced in men than in women.

CONCLUSION

Despite repeated calls for improved secondary fracture prevention, an unacceptably large treatment gap remains, with time trends indicating that the problem may be getting worse in recent years.

Bone mineral density gains with a second 12-month course of romosozumab therapy following placebo or denosumab

Romosozumab is a therapy that stimulates bone formation and reduces bone resorption. In this study of postmenopausal women with low BMD, a second course of romosozumab following a period off treatment or on denosumab increased or maintained BMD, respectively, and was well tolerated, providing insight into treatment sequence options.

INTRODUCTION

In patients with high fracture risk, therapies that stimulate bone formation provide rapid BMD gains; currently available agents, parathyroid hormone receptor agonists, are limited to a 2-year lifetime exposure and generally used for a single treatment course. However, for long-term osteoporosis management, a second treatment course may be appropriate. Romosozumab, a therapy with the dual effect of increasing bone formation and decreasing bone resorption, reduces fracture risk within 12 months. Here, we report efficacy and safety of a second romosozumab course.

METHODS

In this phase 2, dose-finding study, postmenopausal women with low bone mass (T-score ≤ - 2.0 and ≥ - 3.5) received romosozumab or placebo (month 0-24) followed by placebo or denosumab (month 24-36); participants then received a year of romosozumab (month 36-48).

RESULTS

Of 167 participants who entered the month 36-48 period, 35 had been initially randomized to romosozumab 210 mg monthly. In participants who received romosozumab 210 mg monthly followed by placebo, a second romosozumab course (n = 19) increased BMD by amounts similar to their initial treatment (month 0-12) at the lumbar spine (12.4%; 12.0%, respectively) and total hip (6.0%; 5.5%, respectively). Following denosumab, a second romosozumab course (n = 16) increased BMD at the lumbar spine (2.3%) and maintained BMD at the total hip. Safety profiles were similar between first and second romosozumab courses.

CONCLUSIONS

After 12 months off-treatment, a second romosozumab course again led to rapid and large BMD gains. Following denosumab, BMD gains with romosozumab were smaller than with initial treatment. No new safety findings were observed during the second course.

Long-term denosumab treatment restores cortical bone loss and reduces fracture risk at the forearm and humerus: analyses from the FREEDOM Extension cross-over group

Upper limb fractures (including wrist, forearm, and humerus) represent a significant burden among postmenopausal women with osteoporosis. Up to 7 years of treatment with denosumab resulted in an increase in bone mineral density and decrease in fractures in upper limb sites.

INTRODUCTION

Upper limb (wrist, forearm, and humerus) fractures are a significant burden in osteoporosis, associated with significant morbidity and mortality. Denosumab, a monoclonal antibody against RANK ligand, increases bone mineral density (BMD) and decreases vertebral, nonvertebral, and hip fractures. Here, we evaluated the long-term effect of denosumab treatment on upper limb fracture risk and BMD.

METHODS

In the FREEDOM trial, subjects were randomized 1:1 to receive every-6-month denosumab 60 mg or placebo subcutaneously for 3 years, after which all subjects could receive denosumab for up to 7 years (Extension). Among placebo subjects who completed FREEDOM and enrolled in the Extension, wrist, forearm, humerus, and upper limb fracture rates and rate ratios between different time periods (FREEDOM years 1-3, Extension years 1-3, and Extension years 4-7) were computed. BMD at the ultradistal radius, 1/3 radius, and total radius was analyzed in a subset of subjects in a BMD substudy.

RESULTS

This analysis included 2207 subjects (116 in the BMD substudy). Fracture rates decreased over the 7-year Extension; fracture rate ratios between Extension years 4-7 (denosumab) and FREEDOM years 1-3 (placebo) reduced significantly for the wrist (0.57), forearm (0.57), humerus (0.42), and upper limb (0.52; p < 0.05 for all). Percentage increase in BMD from Extension baseline at the ultradistal radius, 1/3 radius, and total radius was significant by Extension year 7 (p < 0.05 for all).

CONCLUSIONS

Long-term treatment with denosumab decreases upper limb fracture risk and increases forearm BMD, suggesting beneficial effects on both cortical and trabecular bone accruing over time.

Relationship Between Bone Mineral Density T-Score and Nonvertebral Fracture Risk Over 10 Years of Denosumab Treatment

Although treat-to-target strategies are being discussed in osteoporosis, there is little evidence of what the target should be to reduce fracture risk maximally. We investigated the relationship between total hip BMD T-score and the incidence of nonvertebral fracture in women who received up to 10 years of continued denosumab therapy in the FREEDOM (3 years) study and its long-term Extension (up to 7 years) study. We report the percentages of women who achieved a range of T-scores at the total hip or femoral neck over 10 years of denosumab treatment (1343 women completed 10 years of treatment). The incidence of nonvertebral fractures was lower with higher total hip T-score. This relationship plateaued at a T-score between -2.0 and -1.5 and was independent of age and prevalent vertebral fractures, similar to observations in treatment-naïve subjects. Reaching a specific T-score during denosumab treatment was dependent on the baseline T-score, with higher T-scores at baseline more likely to result in higher T-scores at each time point during the study. Our findings highlight the importance of follow-up BMD measurements in patients receiving denosumab therapy because BMD remains a robust indicator of fracture risk. These data support the notion of a specific T-score threshold as a practical target for therapy in osteoporosis. © 2019 The Authors Journal of Bone and Mineral Research published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research (ASBMR).

Risk of imminent fracture following a previous fracture in a Swedish database study

This study examined the imminent risk of a future fracture within 1 and 2 years following a first fracture in women aged 50 years and older and assessed independent factors associated with risk of subsequent fractures. The study highlights the need to intervene rapidly after a fracture to prevent further fractures.

INTRODUCTION

This study aims to determine the imminent risk of subsequent fractures within 1 and 2 years following a first fracture and to assess independent factors associated with subsequent fractures.

METHODS

Retrospective, observational cohort study of women aged ≥ 50 years with a fragility fracture was identified from Swedish national registers. Clinical/demographic characteristics at the time of index fracture and cumulative fracture incidences up to 12 and 24 months following index fracture were calculated. Risk factors for subsequent fracture were identified using multivariate regression analysis.

RESULTS

Two hundred forty-two thousand one hundred eight women (mean [SD] age 74 [12.5] years) were included. The cumulative subsequent fracture incidence at 12 months was 7.1% (95% confidence interval [CI], 6.9-7.2) and at 24 months was 12.0% (95% CI, 11.8-12.1). The rate of subsequent fractures was highest in the first month (~ 15 fractures per 1000 patient-years) and remained steady between 4 and 24 months (~ 5 fractures/1000 patient-years). Higher age was an independent risk factor for imminent subsequent fractures (at 24 months, sub-distribution hazard ratio [HR], 3.07; p < 0.001 for women 80-89 years [reference 50-59 years]). Index vertebral fracture was a strong independent risk factor for subsequent fracture (sub-distribution HR, 2.72 versus hip fracture; p < 0.001 over 12 months; HR, 2.23; p < 0.001 over 24 months).

CONCLUSIONS

Our findings highlight the need to intervene rapidly after any fragility fracture in postmenopausal women. The occurrence of a fragility fracture provides healthcare systems with a unique opportunity to intervene to reduce the increased risk of subsequent fractures.

Effect of denosumab on trabecular bone score in postmenopausal women with osteoporosis

Trabecular bone score (TBS) assesses bone quality in the lumbar spine using dual-energy X-ray absorptiometry (DXA) scans. In postmenopausal women with osteoporosis, denosumab significantly improved TBS independently of bone mineral density (BMD). This practical technique may have a role in managing patients with osteoporosis.

INTRODUCTION

TBS, a gray-level texture index determined from lumbar spine DXA scans, correlates with bone microarchitecture and enhances assessment of vertebral fracture risk independently of BMD. In the FREEDOM study, denosumab increased BMD and reduced new vertebral fractures in postmenopausal women with osteoporosis. This retrospective analysis explored the effect of denosumab on TBS and the association between TBS and BMD in FREEDOM.

METHODS

Postmenopausal women with lumbar spine or total hip BMD T-score <-2.5 and -4.0 or higher at both sites received placebo or denosumab 60 mg subcutaneously every 6 months. TBS indices were determined from DXA scans at baseline and months 12, 24, and 36 in a subset of 285 women (128 placebo, 157 denosumab) who had TBS values at baseline and ≥1 postbaseline visit.

RESULTS

Baseline characteristics were comparable between treatment groups; mean (SD) lumbar spine BMD T-score was -2.79 (0.64), and mean (standard deviation [SD]) TBS was 1.200 (0.101) overall. In the placebo group, BMD and TBS increased by ≤0.2% or decreased from baseline at each visit. In the denosumab group, progressive increases from baseline at 12, 24, and 36 months were observed for BMD (5.7, 7.8, and 9.8%) and TBS (1.4, 1.9, and 2.4%). Percentage changes in TBS were statistically significant compared with baseline (p < 0.001) and placebo (p ≤ 0.014). TBS was largely unrelated to BMD, regardless of treatment, either at baseline or for annual changes from baseline (all r ² ≤ 0.06).

CONCLUSIONS

In postmenopausal women with osteoporosis, denosumab significantly improved TBS independently of BMD.

Comorbidity indices for clinical trials: adaptation of two existing indices for use with the FREEDOM trial in women with postmenopausal osteoporosis

Two comorbidity indices were adapted for use in the FREEDOM trial and significantly correlated with the number of medications and impaired health status at baseline. The indices have applications for the analysis of clinical trial data and would allow for the appropriate adjustment of comorbidities when evaluating clinical trial outcomes.

INTRODUCTION

The purpose of this study is to adapt two published comorbidity indices for use with the FREEDOM clinical trial evaluating postmenopausal women with osteoporosis.

METHODS

FREEDOM enrolled women aged 60-90 years with a bone mineral density T-score <-2.5 at the lumbar spine or total hip and ≥-4.0 at both sites. Comorbidity indices were calculated using methods described by Sangha (Arthritis Rheum 49:156-163, 2003) and Wolfe (J Rheumatol 37:305-315, 2010) following modification. The adapted Sangha index included 12 conditions with a summary score of 0-12; the adapted Wolfe index included 7 conditions with a weighted summary score of 0-8. Higher scores indicated greater comorbidity. A panel of clinicians independently reviewed subjects' medical histories using a systematic process based on Medical Dictionary for Regulatory Activities (MedDRA) preferred terms to map specified comorbid conditions. Spearman correlations between the adapted indices and baseline subject characteristics expected to be associated with comorbidities were examined.

RESULTS

Of the 7808 subjects in this study, 74 % had ≥1 comorbidities based on the adapted Sangha or Wolfe comorbidity indices. The mean (SD) adapted Sangha and Wolfe comorbidity indices were 1.4 (1.2) and 1.4 (1.3), respectively. Both indices correlated positively with age, body mass index, and the number of medications (r = 0.54 to 0.55) at baseline and inversely correlated with health-related quality of life (r = -0.22 to -0.30) (all P < 0.0001). Further, when either the adapted Sangha or Wolfe index was included as a covariate for assessing mortality over 36 months in the FREEDOM population, the hazard ratio of the comorbidity index indicated that the mortality risk increased by 27 or 28 %, respectively, for each unit increase in the adapted index (both P < 0.0001).

CONCLUSIONS

Our work suggests these comorbidity indices may be adapted for use with clinical trial data, thereby allowing for the appropriate adjustment and reporting of covariates in the evaluation of clinical trial outcomes in an osteoporotic population.

The effect of 8 or 5 years of denosumab treatment in postmenopausal women with osteoporosis: results from the FREEDOM Extension study

The FREEDOM study and its Extension provide long-term information about the effects of denosumab for the treatment of postmenopausal osteoporosis. Treatment for up to 8 years was associated with persistent reduction of bone turnover, continued increases in bone mineral density, low fracture incidence, and a favorable benefit/risk profile.

INTRODUCTION

This study aims to report the results through year 5 of the FREEDOM Extension study, representing up to 8 years of continued denosumab treatment in postmenopausal women with osteoporosis.

METHODS

Women who completed the 3-year FREEDOM study were eligible to enter the 7-year open-label FREEDOM Extension in which all participants are scheduled to receive denosumab, since placebo assignment was discontinued for ethical reasons. A total of 4550 women enrolled in the Extension (2343 long-term; 2207 cross-over). In this analysis, women in the long-term and cross-over groups received denosumab for up to 8 and 5 years, respectively.

RESULTS

Throughout the Extension, sustained reduction of bone turnover markers (BTMs) was observed in both groups. In the long-term group, mean bone mineral density (BMD) continued to increase significantly at each time point measured, for cumulative 8-year gains of 18.4 and 8.3 % at the lumbar spine and total hip, respectively. In the cross-over group, mean BMD increased significantly from the Extension baseline for 5-year cumulative gains of 13.1 and 6.2 % at the lumbar spine and total hip, respectively. The yearly incidence of new vertebral and nonvertebral fractures remained low in both groups. The incidence of adverse and serious adverse events did not increase over time. Through Extension year 5, eight events of osteonecrosis of the jaw and two events of atypical femoral fracture were confirmed.

CONCLUSIONS

Denosumab treatment for up to 8 years was associated with persistent reductions of BTMs, continued BMD gains, low fracture incidence, and a consistent safety profile.

Further reductions in nonvertebral fracture rate with long-term denosumab treatment in the FREEDOM open-label extension and influence of hip bone mineral density after 3 years

Limited data exist on the efficacy of long-term therapies for osteoporosis. In osteoporotic postmenopausal women receiving denosumab for 7 years, nonvertebral fracture rates significantly decreased in years 4-7 versus years 1-3. This is the first demonstration of a further benefit on fracture outcomes with long-term therapy for osteoporosis.

INTRODUCTION

This study aimed to evaluate whether denosumab treatment continued beyond 3 years is associated with a further reduction in nonvertebral fracture rates.

METHODS

Participants who completed the 3-year placebo-controlled Fracture REduction Evaluation of Denosumab in Osteoporosis every 6 Months (FREEDOM) study were invited to participate in an open-label extension. The present analysis includes 4,074 postmenopausal women with osteoporosis (n = 2,343 long-term; n = 1,731 cross-over) who enrolled in the extension, missed ≤1 dose during their first 3 years of denosumab treatment, and continued into the fourth year of treatment. Comparison of nonvertebral fracture rates during years 1-3 of denosumab with that of the fourth year and with the rate during years 4-7 was evaluated.

RESULTS

For the combined group, the nonvertebral fracture rate per 100 participant-years was 2.15 for the first 3 years of denosumab treatment (referent) and 1.36 in the fourth year (rate ratio [RR] = 0.64; 95 % confidence interval (CI) = 0.48 to 0.85, p = 0.003). Comparable findings were observed in the groups separately and when nonvertebral fracture rates during years 1-3 were compared to years 4-7 in the long-term group (RR = 0.79; 95 % CI = 0.62 to 1.00, p = 0.046). Fracture rate reductions in year 4 were most prominent in subjects with persisting low hip bone mineral density (BMD).

CONCLUSIONS

Denosumab treatment beyond 3 years was associated with a further reduction in nonvertebral fracture rate that persisted through 7 years of continuous denosumab administration. The degree to which denosumab further reduces nonvertebral fracture risk appears influenced by the hip bone density achieved with initial therapy.

Advanced CT based in vivo methods for the assessment of bone density, structure, and strength

Based on spiral 3D tomography a large variety of applications have been developed during the last decade to asses bone mineral density, bone macro and micro structure, and bone strength. Quantitative computed tomography (QCT) using clinical whole body scanners provides separate assessment of trabecular, cortical, and subcortical bone mineral density (BMD) and content (BMC) principally in the spine and hip, although the distal forearm can also be assessed. Further bone macrostructure, for example bone geometry or cortical thickness can be quantified. Special high resolution peripheral CT (hr-pQCT) devices have been introduced to measure bone microstructure for example the trabecular architecture or cortical porosity at the distal forearm or tibia. 3D CT is also the basis for finite element analysis (FEA) to determine bone strength. QCT, hr-pQCT, and FEM are increasingly used in research as well as in clinical trials to complement areal BMD measurements obtained by the standard densitometric technique of dual x-ray absorptiometry (DXA). This review explains technical developments and demonstrates how QCT based techniques advanced our understanding of bone biology.

National Bone Health Alliance Bone Turnover Marker Project: current practices and the need for US harmonization, standardization, and common reference ranges

This position paper reviews how the National Bone Health Alliance (NBHA) will execute a project to help assure health professionals of the clinical utility of bone turnover markers; the current clinical approaches concerning osteoporosis and the status and use of bone turnover markers in the USA; the rationale for focusing this effort around two specific bone turnover markers; the need to standardize bone marker sample collection procedures, reference ranges, and bone turnover marker assays in clinical laboratories; and the importance of harmonization for future research of bone turnover markers.

INTRODUCTION

Osteoporosis is a major global health problem, with the prevalence and incidence of osteoporosis for at-risk populations estimated to be 44 million Americans. The potential of bone markers as an additional tool for health care professionals to improve patient outcomes and impact morbidity and mortality is crucial in providing better health care and addressing rising health care costs. This need to advance the field of bone turnover markers has been recognized by a number of organizations, including the International Osteoporosis Foundation (IOF), National Osteoporosis Foundation, International Federation of Clinical Chemistry, and Laboratory Medicine (IFCC), and the NBHA.

METHODS

This position paper elucidates how this project will standardize bone turnover marker sample collection procedures in the USA, establish a USA reference range for one bone formation (serum procollagen type I N propeptide, s-PINP) and one bone resorption (serum C-terminal telopeptide of type I collagen, s-CTX) marker, and standardize bone turnover marker assays used in clinical laboratories. This effort will allow clinicians from the USA to have confidence in their use of bone turnover markers to help monitor osteoporosis treatment and assess future fracture risk. This project builds on the recommendations of the IOF/IFCC Bone Marker Standards Working Group by developing USA reference standards for s-PINP and s-CTX, the markers identified as most promising for use as reference markers.

RESULTS

The goals of this project will be realized through the NBHA and will include its governmental, academic, for-profit, and non-profit sector stakeholders as well as major academic and commercial laboratories. Upon completion, a parallel effort will be pursued to make bone turnover marker measurements reliable and accepted by all health care professionals for facilitating treatment decisions and ultimately be reimbursed by all health insurance payers.

CONCLUSIONS

Successful completion of this project will help assure health professionals from the USA of the clinical utility of bone turnover markers and ties in with the parallel effort of the IOF/IFCC to develop worldwide bone turnover reference ranges.

Denosumab improves density and strength parameters as measured by QCT of the radius in postmenopausal women with low bone mineral density

BACKGROUND

Bone strength is determined by both cortical and trabecular bone compartments and can be evaluated radiologically through measurement of bone density and geometry. Quantitative computed tomography (QCT) separately assesses cortical and trabecular bone reliably at various sites, including the distal radius where there is a gradation of cortical and trabecular bone. We evaluated the effect of denosumab, a fully human monoclonal antibody that inhibits RANK ligand, on distal radius QCT in women with low bone mass to assess the impact of this novel therapy separately on trabecular and cortical bone.

METHODS

Postmenopausal women (n=332) with spine areal bone mineral density (BMD) T-scores between -1.0 and -2.5 received denosumab 60 mg or placebo every 6 months during the 24-month study. QCT measurements along the distal radius were made using a whole-body computed tomography scanner and were used to determine the percentage change from baseline in volumetric BMD; volumetric bone mineral content (BMC); cortical thickness; volume; circumference; and density-weighted polar moment of inertia (PMI), a derived index of bone strength.

RESULTS

Denosumab treatment significantly increased total BMD and BMC along the radius (proximal, distal, and ultradistal sections). At 24 months, the ultradistal region had the greatest percentage increase in total BMD (4.7% [95% CI, 3.6-5.7]; P<0.001) and total BMC (5.7% [95% CI, 4.8-6.6]; P<0.001) over placebo. When cortical and trabecular bone at the proximal and distal regions were separately assessed, cortical bone had significant (P<0.001) increases in BMD, BMC, and thickness, and trabecular bone had a significant increase in BMD relative to placebo (P<0.05). Bone strength, estimated by density-weighted PMI, significantly increased compared with placebo after 6 months of treatment, with the largest percentage increase occurring at 24 months in the ultradistal region (6.6% [95% CI, 5.6-7.6]; P<0.0001).

CONCLUSIONS

QCT measurements demonstrated that denosumab significantly increased BMD, BMC, and PMI along the radius over 24 months. Additionally, denosumab prevented the decrease in QCT-measured cortical thickness observed in the placebo group. These data extend the evidence from previous dual-energy X-ray absorptiometry studies for a positive effect of denosumab on both the cortical and trabecular bone compartments and propose a possible mechanism for the reduction in fracture risk achieved with denosumab therapy.

Studies on the potential mediators of skeletal changes occurring during puberty in girls

In this study we evaluated the role of cytokines and insulin-like growth factor (IGF) system in mediating the skeletal changes that occur during puberty by determining the relationship between serum levels of cytokines and IGF system components vs. 1) bone formation and resorption parameters in serum and urine, 2) bone density, and 3) metacarpal bone indexes in 65 pubertal girls. Lumbar bone mineral density and metacarpal width increased significantly both between Tanner stages (TS) II and III and between TS III and IV, whereas metacarpal length and serum levels of stimulatory IGF system components increased significantly only between TS II and III. Biochemical markers of bone turnover were significantly less in TS IV girls than in TS II and III girls. In general, serum levels of IGF system components showed a significant positive correlation to bone density in TS II and III girls, whereas bone resorption markers corrected for creatinine showed a significant negative correlation to bone density in TS III and IV girls. Serum levels of IGF system components showed a significant positive correlation to serum osteocalcin levels as well as metacarpal width in TS II girls, whereas urinary levels of bone resorption markers showed a significant negative correlation to metacarpal width in TS IV girls. Serum levels of interleukin-6 were decreased during late puberty and were negatively correlated with bone density in TS III and IV girls. Our data are consistent with a model in which the sex steroid hormone-induced increase in the IGF system leads to an increase in longitudinal growth and periosteal bone expansion, whereas the sex steroid hormone-induced reduction in bone turnover (possibly via cytokines) leads to an increase in cortical thickness via endosteal regulation.

Fixation of humeral prostheses and axial micromotion

Surgeons often avoid cementing a proximal humeral prosthesis. Occasionally bony augmentation is needed. This study was undertaken to compare proximal cementation in combination with distal press with total cementation or press fit alone. In phase 1 axial micromotion with axial loading was measured in 15 pairs of humeri: 5 fully cemented versus proximally cemented, 5 fully cemented versus press fit, and 5 proximally cemented versus press fit. X-ray films of the specimens were obtained to assess canal fill. In phase 2 axial micromotion was measured in 5 pairs of high mineral density and 5 pairs of low mineral density to compare proximal cementation with press fit. The 3 M modular prosthesis was used in both phases. No difference was found in phase 1 among the 3 fixation techniques. A strong reverse statistical correlation (P = .007) (r = .55) was seen between axial micromotion and fill of the canal with the prosthesis. In the second phase no statistically significant difference was found between the techniques of fixation or between the 2 bone densities. Fill of the canal at the distal end of the prosthesis was the only variable found that affected axial micromotion, but it accounted for only approximately 30% of the variance. Bone quality and augmentation of the proximal bone with cement did not affect axial micromotion in this experiment but warrant further study.

Multiple myeloma. Diagnostic clues in a patient presenting with incapacitating arthralgias

Multiple myeloma is characterized by the production of a monoclonal immunoglobulin, free monoclonal light chains, or both. Although bone pain is the classic presentation, multiple myeloma should be a consideration in differential diagnosis in elderly patients with arthritic complaints if other typical symptoms or laboratory abnormalities, such as anemia, hypercalcemia, and elevated ESR, are present. A combination of radiation therapy and chemotherapy is the usual treatment.

Racial differences in bone density between young adult black and white subjects persist after adjustment for anthropometric, lifestyle, and biochemical differences

This study tested whether racial differences in bone density can be explained by differences in bone metabolism and lifestyle. A cohort of 402 black and white men and women, ages 25-36 yr, was studied at the Kaiser Permanente Medical Care Program in Northern California, a prepaid health plan. Body composition (fat, lean, and bone mineral density) was measured using a Hologic-2000 dual-energy x-ray densitometer. Muscle strength, blood and urine chemistry values related to calcium metabolism, bone turnover, growth factors, and level of sex and adrenal hormones were also measured. Medical history, physical activity, and lifestyle were assessed. Statistical analyses using t- and chi-square tests and multiple regression were done to determine whether racial difference in bone density remained after adjustment for covariates. Bone density at all skeletal sites was statistically significantly greater in black than in white subjects; on average, adjustment for covariates reduced the percentage density differences by 42% for men and 34% for women. Adjusted bone density at various skeletal sites was 4.5-16.1% higher for black than for white men and was 1.2-7.3% higher for black than for white women. We concluded that racial differences in bone mineral density are not accounted for by clinical or biochemical variables measured in early adulthood.

The increase in spinal bone density that occurs in response to fluoride therapy for osteoporosis is not maintained after the therapy is discontinued

In 44 osteoporotic subjects who had been treated with fluoride for 37 +/- 16 months, the fluoride was discontinued because they had shown fluoride-dependent increases in trabecular spinal bone densities from low initial levels (below the fracture threshold) to values that were equivalent to normal peak bone densities in the spines of young adults. During the subsequent period, after discontinuation of the fluoride therapy (i.e. 19 +/- 9 months), spinal bone density decreased in 73% of the subjects (i.e. 32 of 44, p < 0.03), at a rate that was comparable to the rate of the previous gain that had occurred during the treatment with fluoride (i.e. -3.23 +/- 2.39 mg/cm3 per month, compared with + 3.91 +/- 1.96 mg/cm3 per month in this, subgroup of patients, p < 0.001). Although 9 of the 44 subjects showed continuing increases in spinal bone density after discontinuation of the fluoride therapy, spinal bone density decreased in the entire group of 44 at an average rate of -1.02 +/- 4.72 mg/cm3 per month (p < 0.001, compared with the rate of the previous gain during the treatment with fluoride; i.e. +3.83 +/- 1.82 mg/cm3 per month). Surprisingly, our data showed that the rate of decrease in spinal bone density during the post-fluoride period was not affected by concurrent (undesigned) treatment with calcium, calcium plus estrogen, or calcium plus calcitriol. The cessation of fluoride therapy was also associated with a decrease in serum alkaline phosphatase activity (i.e. a decrease from the elevated levels that were observed during the period of fluoride therapy, back to the original, pre-treatment levels; p < 0.001), and that the rate of spinal bone loss after cessation of fluoride could be correlated with the prior rate of increase in serum alkaline phosphatase activity that had occurred during the treatment with fluoride (n = 44, r = 0.312, p = 0.039). Together, the observations from this retrospective analysis of data obtained from our clinical subjects suggest that fluoride-treated osteoporotic subjects who have exhibited increases in trabecular spinal bone density are at risk for bone loss after discontinuation of the fluoride therapy.

Development, validation, and application of a radioimmunoassay for insulin-like growth factor binding protein-5 in human serum and other biological fluids

Insulin-like growth factor binding proteins (IGFBPs) serve as transport proteins for the IGFs and modulate their biological effects. In order to evaluate the relative contribution of IGFBP-5 to the IGF binding capacity of serum and other biological fluids and to study more accurately the in vivo regulation of serum IGFBP-5, we have developed an RIA for IGFBP-5 using recombinant human IGFBP-5 as the antigen, tracer, and standard. The validity of the IGFBP-5 RIA was established from the following data: 1) recombinant human IGFBP-5 and purified human bone-derived IGFBP-5 inhibited the binding of tracer to the antisera in an identical manner; 2) the immunoreactive IGFBP-5 in serum co-migrated with recombinant human IGFBP-5 in both sodium dodecyl sulfate polyacrylamide gel electrophoresis and high performance gel filtration chromatography; 3) none of the other known IGFBPs (IGFBP-1, -2, -3, -4, and -6) exhibited significant cross-reactivity; 4) the addition of IGF-I or IGF-II to the samples did not affect the recovery of IGFBP-5; and 5) the recovery of the exogenously added IGFBP-5 to serum was greater than 90%. In order to further validate our IGFBP-5 RIA, measurements of IGFBP-5 were carried out in the conditioned media samples collected from human bone cells treated with effectors that are known to influence IGFBP-5 production. Treatment of human bone cells with bone morphogenetic protein-7, which increases IGFBP-5 production, caused an increase in IGFBP-5 protein levels; dexamethasone, which decreases IGFBP-5 production, caused a decrease in IGFBP-5 protein levels measured in the conditioned medium by this RIA. Application of this RIA to the measurement of the IGFBP-5 level in human serum revealed that the circulating level of IGFBP-5 in healthy women decreased from 664 +/- 108 ug/L in prepubertal girls to 222 +/- 42 ug/L in women ages 61-85 yr (P < 0.001). There was also a small but significant decrease in the mean serum level of IGFBP-5 in women ages 23-39 yr compared with the level in prepubertal girls (589 +/- 66 vs. 664 +/- 108 ug/L, P < 0.05). Additional studies with this assay may provide an insight into the physiological mechanism that regulates IGFBP-5 production in vivo and the potential role of this protein as an IGF transport protein in serum and other biological fluids.

Biochemical markers of bone turnover for the clinical assessment of bone metabolism

Despite these potential problems, biochemical bone markers are the single most sensitive method for monitoring acute changes in bone metabolism. For example, subcutaneous injections of recombinant human insulin-like growth factor I cause a measurable increase in both procollagen and urinary DPD in as little as 1 day. Similarly, it is possible to measure a significant decrease in bone formation as determined by decreases in serum levels of ALP, OC, and C-PCP within 12 hours after the beginning of a PTH infusion study. Additionally, an increase in DPD/cr was determined within 24 hours of the start of bed rest. These changes, seen within 24 hours, are far earlier than could be detected by any other method of monitoring bone metabolism. Thus, biochemical assays have opened a new era where changes in bone metabolism can be detected in hours to days. This acute detectability should be especially helpful to the development of new drugs and the optimization of the use of approved drugs. Accordingly, definite dose-response studies can now be done in a reasonable time. For osteoporosis therapy there are reasons to consider cyclic drug administration, such as avoiding drug resistance (PTH or calcitonin), avoiding overtreatment (bisphosphonates), or avoiding a possible mineralization defect (fluoride). By using biochemical assays, we can determine the optimum amount of "on time" and "off time" in cyclic therapy. Of the bone formation assays, ALP, OC, and PCP, we recommend for routine use the OC assay because of its high discriminant power and because it has been better characterized, in terms of clinical application, than the PCP assays and the ALP IRMA. If, however, the serum cannot be drawn at a specific time in all patients to be studied, we recommend the ALP assay because, unlike the OC assay, it shows no diurnal variation. Of the bone resorption assays, HYP, TRAP, GHYL, and PYD/DPD, we recommend the urine PYD/DPD assay (adjusted for creatinine) because it is commercially available and because, along with the urine GHYL assay, it is the most sensitive bone resorption assay. Established guidelines for the use of assays in patient care is not yet available, largely because of the large intrapatient variation seen with most assays. Once this problem is resolved, it should be possible to apply biochemical assays to routine clinical practice. For example, if the patient has a urine DPD/cr (indicating a high bone resorption rate), the patient would be selected for antiresorptive therapy, and subsequently the urine DPD/cr assay would be repeated during therapy to determine the effective dose of the drug.(ABSTRACT TRUNCATED AT 400 WORDS)

Pharmacokinetic profile of a new fluoride preparation: sustained-release monofluorophosphate

The pharmacokinetic profiles of a sustained-release monofluorophosphate (MFP-SR) preparation (76 mg) and of plain MFP (76 mg) were compared in six osteoporotic females. These studies were performed in a randomized, crossover, double-blind design to select a preparation that would result in therapeutic serum levels while avoiding high serum peak values. Following a single dose of 76 mg MFP-SR, the serum fluoride levels remained within the accepted therapeutic range (5-10 microM/liter) for 24 hours. In contrast, following a single dose of 76 mg plain MFP, serum fluoride levels exhibited a wide circadian fluctuation and serum levels approximately threefold higher than those of the MFP-SR preparation (9.5 +/- 1.6 vs 3.5 +/- 0.8 microM/liter, P < 0.005). Compared with plain MFP, the sustained-release MFP had a significantly lower peak concentration (Cmax MFP-SR: 10.6 +/- 3 vs CmaxMFP: 18.9 +/- 5 microM/liter, P < 0.005) and a significantly longer absorption lag time (TmaxMFP-SR 7.3 +/- 1.6 vs TmaxMFP: 3.0 +/- 0.6 h, P < 0.05). Twenty-four-hour urinary fluoride excretion after ingestion of plain or SR fluoride was significantly increased from pretreatment values documenting absorption with either MFP formulation. Our results show that the use of sustained-release MFP preparation that we tested prevents the development of high peak levels associated with the use of plain MFP preparations. Furthermore, a single dose of MFP-SR resulted in serum fluoride levels within the accepted range of 5-10 microM/liter for 24 hours.

Reference standards for quantification of skeletal alkaline phosphatase activity in serum by heat inactivation and lectin precipitation

Putative standards of skeletal alkaline phosphatase (ALP) (from bone, bone cells, osteosarcoma cells, and Pagetic serum) and hepatic ALP (from cholestatic serum and bile) were used to compare three methods for quantifying skeletal ALP activity in serum: heat inactivation, precipitation with wheat germ agglutinin (WGA), and precipitation with concanavalin A (Con A). All the skeletal ALP standards were similarly sensitive to heat inactivation, as were the hepatic ALP standards. Heat inactivation separated skeletal from hepatic ALP by a 50% difference in remaining ALP activities (e.g., 23% and 74% remaining skeletal and hepatic ALP activities after 30 min at 52 degrees C). Differential precipitations with WGA and with Con A were less efficient at separating skeletal from hepatic ALP (maximum differences of < 30% remaining ALP activity). Although both types of hepatic ALP standard (cholestatic serum and bile) were precipitated with similar efficiencies by WGA and Con A, the skeletal ALP standards were not (e.g., at 2.7 g/L, WGA precipitated 78-86% of the ALP activity in Pagetic serum, but only 49% of the ALP activity in extracts of human bone). These data suggest that heat inactivation is preferable to precipitation with WGA or Con A for quantifying skeletal ALP activity in serum: it better separates skeletal from hepatic ALP activity and is not sensitive to glycosyl heterogeneity.

Reference standards for quantification of skeletal alkaline phosphatase activity in serum by heat inactivation and lectin precipitation

Putative standards of skeletal alkaline phosphatase (ALP) (from bone, bone cells, osteosarcoma cells, and Pagetic serum) and hepatic ALP (from cholestatic serum and bile) were used to compare three methods for quantifying skeletal ALP activity in serum: heat inactivation, precipitation with wheat germ agglutinin (WGA), and precipitation with concanavalin A (Con A). All the skeletal ALP standards were similarly sensitive to heat inactivation, as were the hepatic ALP standards. Heat inactivation separated skeletal from hepatic ALP by a 50% difference in remaining ALP activities (e.g., 23% and 74% remaining skeletal and hepatic ALP activities after 30 min at 52 degrees C). Differential precipitations with WGA and with Con A were less efficient at separating skeletal from hepatic ALP (maximum differences of &lt; 30% remaining ALP activity). Although both types of hepatic ALP standard (cholestatic serum and bile) were precipitated with similar efficiencies by WGA and Con A, the skeletal ALP standards were not (e.g., at 2.7 g/L, WGA precipitated 78-86% of the ALP activity in Pagetic serum, but only 49% of the ALP activity in extracts of human bone). These data suggest that heat inactivation is preferable to precipitation with WGA or Con A for quantifying skeletal ALP activity in serum: it better separates skeletal from hepatic ALP activity and is not sensitive to glycosyl heterogeneity.

Evidence that fluoride therapy increases trabecular bone density in a peripheral skeletal site

We measured the spinal bone density (SBD) and femoral condyle bone density (FCD) in normal and osteoporotic females (n = 219) both before and during fluoride therapy. SBD and FCD in untreated osteoporotics were significantly lower (P < 0.05) than those in the age-matched controls. SBD and FCD were correlated in the untreated (r = 0.62; P < 0.0001) as well as in the fluoride-treated osteoporotics (r = 0.42; P < 0.0001). SBD and FCD were significantly increased (P < 0.05) in response to fluoride therapy. The average rates of increase in FCD and SBD were similar (1.3 +/- 1.3 vs. 1.24 +/- 1.4 mg/cc.month). We conclude that the osteogenic action of fluoride is not limited to the axial skeleton. An increase in trabecular bone density also occurs at peripheral weight-bearing sites such as the femoral condyle.