Study design in osteoporosis: a European perspective

Clinical therapeutic trials

The term clinical trial implies an investigation of a therapeutic intervention in the pursuit of evidence of benefit, short or sustained, and observations on the possibility of toxicity related to the therapeutic intervention. It is possible that the first clinical trial took place in the court of the Babylonian King Nebuchadnezzar circa 600 BC, as recorded in Chapter 1 of the Book of Daniel, verse 3-20. However, it is in the last 500 years that there has been good written documentation at attempts to interpret therapeutic benefit from the use of treatments. Lind's demonstration on the usefulness of oranges and lemons in the treatment of scurvy in 1747, and the unethical experiment by Edward Jenner (1749-1823) on the inoculation in 1796, of an 8-year-old boy, with cow pox obtained from a milk maid, followed by an attempt to give the young boy smallpox by direct inoculation 18 days later, are striking examples of clinical trials. Human ethics, strict clinical observations, statistics, the governed scientific purity of therapeutic agents, and safety testing of therapeutics, devices, and physical interventions, have created the basis for the modern clinical trial.

Denosumab compared to other treatments to prevent or treat osteoporosis in individuals at risk of fracture: a systematic review and meta-analysis

The aim of this review is to compare the efficacy and safety of denosumab over other treatments for osteoporosis. The results of this study suggest that the safety of denosumab and its efficacy in reducing fractures is not significantly different from bisphosphonates. Denosumab was, however, more effective in increasing bone mineral density.

INTRODUCTION

This study was conducted to compare the efficacy and safety of denosumab over other pharmacological treatments for osteoporosis in individuals at risk of fracture.

METHODS

Randomised controlled trials comparing denosumab with another pharmacological treatment for osteoporosis were searched in MEDLINE, EMBASE and CENTRAL. Identified articles were screened by two independent reviewers and assessed for inclusion. Data from included studies were extracted and meta-analyses were conducted using random effects models.

RESULTS

Nine studies including a total of 4890 postmenopausal women were identified. The follow-up period varied from 12 to 24 months. In all studies except one, the comparator treatment was a bisphosphonate. There was no statistically significant difference between patients receiving denosumab and those receiving a bisphosphonate in terms of fracture risk (RR[95 % CI] = 1.15 [0.84-1.58]), adverse events (RR[95 % CI] = 0.99 [0.96-1.02]) or deaths (OR[95 % CI] = 0.58 [0.12-2.71]). Withdrawals due to adverse events were less frequent in denosumab than in other treatment groups but the difference did not reach statistical significance (OR[95 % CI] = 0.68 [0.45-1.04]). The percent change in bone mineral density at the total hip, lumbar spine, femoral neck and one-third radius was significantly higher in participants who received denosumab (e.g. mean difference [95 % CI] at the total hip: 1.06 [0.86-1.25]).

CONCLUSIONS

These results suggest that, after 12 to 24 months, the safety and efficacy of denosumab for reducing fracture risk is not significantly different from bisphosphonates despite higher gains in bone mineral density. In a clinical setting, denosumab may demonstrate greater effectiveness.

Treatment of osteoporosis after alendronate or risedronate

Alendronate (ALN) and risedronate (RIS) are ideal as first-choice therapy options in the treatment of postmenopausal osteoporosis. What to do for patients who do not respond adequately to bisphosphonates has not been conclusively determined, but transitioning to other therapies should be considered. The aim of this article is to describe potential alternatives for patients switching from ALN or RIS to other therapies for osteoporosis. A systematic search of PubMed was conducted to find papers that evaluate the effects of switching therapies on fractures, bone mineral density (BMD), or bone turnover markers. Results from 11 studies that prospectively assessed treatment after ALN or RIS in women with postmenopausal osteoporosis were reviewed. All studies are of short duration (all 24 months or less) and assess the topic of transitioning therapy from ALN or RIS. None of the studies had the statistical power to assess fracture-reduction efficacy. Transitioning from ALN to zoledronic acid maintains therapeutic effects for 12 months. Switching to strontium ranelate, denosumab, or teriparatide causes further increases in BMD. Specifically, transitioning to teriparatide could be used for a limited time for select patients but needs to be followed up with anti-resorptive treatment to prevent a loss of the bone gained. There are only few studies-of short duration-that assess the topic of transitioning therapy from ALN or RIS, although this is a very frequent occurrence in clinical practice. This is especially true if the patient has not reached his/her therapy goal. Further long-term studies are needed.

Odanacatib for the treatment of postmenopausal osteoporosis: development history and design and participant characteristics of LOFT, the Long-Term Odanacatib Fracture Trial

SUMMARY

Odanacatib is a cathepsin K inhibitor investigated for the treatment of postmenopausal osteoporosis. Phase 2 data indicate that 50 mg once weekly inhibits bone resorption and increases bone mineral density, with only a transient decrease in bone formation. We describe the background, design and participant characteristics for the phase 3 registration trial.

INTRODUCTION

Odanacatib (ODN) is a selective cathepsin K inhibitor being evaluated for the treatment of osteoporosis. In a phase 2 trial, ODN 50 mg once weekly reduced bone resorption while preserving bone formation and progressively increased BMD over 5 years. We describe the phase III Long-Term ODN Fracture Trial (LOFT), an event-driven, randomized, blinded placebo-controlled trial, with preplanned interim analyses to permit early termination if significant fracture risk reduction was demonstrated. An extension was planned, with participants remaining on their randomized treatment for up to 5 years, then transitioning to open-label ODN.

METHODS

The three primary outcomes were radiologically determined vertebral, hip, and clinical non-vertebral fractures. Secondary end points included clinical vertebral fractures, BMD, bone turnover markers, and safety and tolerability, including bone histology. Participants were women, 65 years or older, with a BMD T-score≤-2.5 at the total hip (TH) or femoral neck (FN) or with a prior radiographic vertebral fracture and a T-score≤-1.5 at the TH or FN. They were randomized to ODN or placebo tablets. All received weekly vitamin D3 (5600 international units (IU)) and daily calcium supplements as needed to ensure a daily intake of approximately 1200 mg.

RESULTS

Altogether, 16,713 participants were randomized at 387 centers. After a planned interim analysis, an independent data monitoring committee recommended that the study be stopped early due to robust efficacy and a favorable benefit/risk profile. Following the base study closeout, 8256 participants entered the study extension.

CONCLUSIONS

This report details the background and study design of this fracture end point trial and describes the baseline characteristics of its participants.

Perspective on post-menopausal osteoporosis: establishing an interdisciplinary understanding of the sequence of events from the molecular level to whole bone fractures

Current drug treatments for post-menopausal osteoporosis cannot eliminate bone fractures, possibly because the mechanisms responsible for bone loss are not fully understood. Although research within various disciplines has significantly advanced the state of knowledge, fundamental findings are not widely understood between different disciplines. For that reason, this paper presents noteworthy experimental findings from discrete disciplines focusing on post-menopausal osteoporosis. These studies have established that, in addition to bone loss, significant changes in bone micro-architecture, tissue composition and micro-damage occur. Cellular processes and molecular signalling pathways governing pathological bone resorption have been identified to a certain extent. Ongoing studies endeavour to determine how such changes are initiated at the onset of oestrogen deficiency. It emerges that, because of the discrete nature of previous research studies, the sequence of events that lead to bone fracture is not fully understood. In this paper, two sequences of multi-scale changes are proposed and the experimental challenges that need to be overcome to fully define this sequence are outlined. Future studies must comprehensively characterize the time sequence of molecular-, cellular- and tissue-level changes to attain a coherent understanding of the events that ultimately lead to bone fracture and inform the future development of treatments for post-menopausal osteoporosis.

Effects of denosumab on bone mineral density and bone turnover in postmenopausal women transitioning from alendronate therapy

Patients treated with bisphosphonates for osteoporosis may discontinue or require a switch to other therapies. Denosumab binds to RANKL and is a potent inhibitor of bone resorption that has been shown to increase bone mineral density (BMD) and decrease fracture risk in postmenopausal women with osteoporosis. This was a multicenter, international, randomized, double-blind, double-dummy study in 504 postmenopausal women > or = 55 years of age with a BMD T-score of -2.0 or less and -4.0 or more who had been receiving alendronate therapy for at least 6 months. Subjects received open-label branded alendronate 70 mg once weekly for 1 month and then were randomly assigned to either continued weekly alendronate therapy or subcutaneous denosumab 60 mg every 6 months and were followed for 12 months. Changes in BMD and biochemical markers of bone turnover were evaluated. In subjects transitioning to denosumab, total hip BMD increased by 1.90% at month 12 compared with a 1.05% increase in subjects continuing on alendronate (p < .0001). Significantly greater BMD gains with denosumab compared with alendronate also were achieved at 12 months at the lumbar spine, femoral neck, and 1/3 radius (all p < .0125). Median serum CTX levels remained near baseline in the alendronate group and were significantly decreased versus alendronate (p < .0001) at all time points with denosumab. Adverse events and serious adverse events were balanced between groups. No clinical hypocalcemic adverse events were reported. Transition to denosumab produced greater increases in BMD at all measured skeletal sites and a greater reduction in bone turnover than did continued alendronate with a similar safety profile in both groups.

Predicting the fracture risk in 2008

Osteoporosis is a generalized disease of bone that increases the fracture risk. Among the multiple factors involved in osteoporosis, some, but not all, are related to bone mass. To decrease osteoporotic fractures, we must be able to identify those patients who require preventive management. Bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry is currently the method of reference for evaluating the fracture risk and deciding whether treatment is in order. Although BMD measurement is specific for detecting high-risk individuals, it misses a notable proportion of individuals who have clinical or epidemiological risk factors for osteoporosis. Therefore, composite scores that rely both on BMD and on validated clinical risk factors have been developed. FRAX, a tool developed under the aegis of the World Health Organization, was designed to predict the 10-year probabilities of sustaining a major osteoporotic fractures or a hip fracture. The cutoff value beyond which treatment should be initiated needs to be determined, based not only on clinical criteria, but also on economic considerations.

Health economics of osteoporosis

Rather than reviewing the many studies of cost effectiveness in osteoporosis, this paper reviews the principles of cost-effectiveness analysis and the gaps in our knowledge that are required to improve such analyses in osteoporosis. These include more information on the cost of fractures and their consequences on health states, particularly on an international basis. New developments include the incorporation of adherence into models, the use of the FRAX tool to assess cost-effectiveness in individuals with any combination of risk factors for fracture, and the setting of intervention thresholds based on cost-effectiveness.

Risk factors for bone mineral density at the calcaneus in 40-59 year-old male workers: a cross-sectional study in Korea

Background

Few epidemiologic studies have attempted to investigate the prevalence and risk factors for osteopenia and osteoporosis in middle-aged Asian men. We performed this study to determine the prevalence and risk factors of osteopenia and osteoporosis in this population.

Methods

This cross-sectional study was conducted from March to July, 2004. The subjects were 2,073 males aged from 40 to 59 years in the KHNP (Korea Hydro & Nuclear Power) workplace-based cohort. Bone mineral density (BMD) was measured by peripheral, dual-energy, X-ray absorptiometry (DXA) at the calcaneus. Anthropometric and lifestyle factors were investigated using a standard, self-reported questionnaire.

Results

BMD was 0.60 ± 0.09 g/cm² (mean ± standard deviation) and was negatively correlated with age (r = -0.18, P < 0.001), but positively correlated with waist-to-hip ratio (WHR; r = 0.15, P < 0.001), body fat (r = 0.10, P < 0.001), BMI (r = 0.35, P < 0.001), height (r = 0.26, P < 0.001), and weight (r = 0.43, P < 0.001).

In multiple linear regression analysis, the independent determinants associated with BMD were increasing age (coefficient = -0.002, P < 0.001), physical activity (≤ 2/week vs. ≥ 3/week; coefficient = 0.017, P < 0.001), WHR (coefficient = -0.796, P < 0.001), body mass index (BMI; coefficient = 0.023, P < 0.001) and smoking status (never vs. ever; coefficient = -0.018, P < 0.001).

Conclusion

We suggest that BMD of the calcaneus is correlated negatively with exposure to smoke and increased WHR, but positively with regular exercise and increased BMI.

Clinical evaluation of novel bisphosphonate dosing regimens in osteoporosis: The role of comparative studies and implications for future studies

BACKGROUND

Daily nitrogen-containing bisphosphonates have shown antifracture efficacy in many studies of postmenopausal osteoporosis. However, current dosing schedules are often inconvenient or impractical for patients. Efforts to reduce dosing frequency to improve adherence (ie, compliance and persistence), and therefore treatment outcomes, are ongoing. Although a number of trial designs can be used to consider the efficacy of therapy, comparing the efficacy of different regimens should only be undertaken in purposefully designed head-to-head studies.

OBJECTIVE

This article summarizes the design and conduct of clinical studies that have investigated alternative bisphosphonate regimens and those that have directly compared different approved bisphosphonates. It also explores the implications for future studies of postmenopausal osteoporosis treatment.

METHODS

Using the terms bisphosphonate, daily, weekly, and monthly, a search (completed in 2006) of the PubMed database was conducted to identify primary English-language publications of pertinent studies comparing either novel with established regimens of the same bisphosphonates or different established bisphosphonates.

RESULTS

The first option is the equivalence or noninferiority bridging study for comparison of new treatment regimens versus the established regimen of the same bisphosphonate, known as the active comparator. Four such studies have led to the registration of novel bisphosphonate dosing regimens designed to provide easier dosing alternatives for patients. The second option is the active comparator study, which compares one bisphosphonate with the most prescribed weekly bisphosphonate. Weekly dosed oral alendronate has previously been shown to be superior (for bone mineral density gains) to daily and weekly dosed oral risedronate. An ongoing noninferiority study, Monthly Oral Therapy with Ibandronate for Osteoporosis Intervention, is comparing weekly alendronate with ibandronate, a monthly oral bisphosphonate.

CONCLUSIONS

The exploration of new dosing schedules and formulations aims to identify the optimal bisphosphonate regimen for postmenopausal osteoporosis. To achieve this, careful consideration must be given to the choice of a scientifically valid study design that effectively, and ethically, meets the study objectives. Given the concerns regarding placebo-controlled antifracture studies, 2 alternative study designs should be considered, both using validated surrogate end points (bone mineral density and biochemical markers of bone turnover) as the principal mode of assessment.