Once-Weekly Injection of Low-Dose Teriparatide (28.2 μg) Reduced the Risk of Vertebral Fracture in Patients with Primary Osteoporosis

Refracture following vertebral fragility fracture when bone fragility is not recognized: summarizing findings from comparator arms of randomized clinical trials

PURPOSE

Since vertebral fragility fractures (VFFs) might increase the risk of subsequent fractures, we evaluated the incidence rate and the refracture risk of subsequent vertebral and non-vertebral fragility fractures (nVFFs) in untreated patients with a previous VFF.

METHODS

We systematically searched PubMed, Embase, and Cochrane Library up to February 2022 for randomized clinical trials (RCTs) that analyzed the occurrence of subsequent fractures in untreated patients with prior VFFs. Two authors independently extracted data and appraised the risk of bias in the selected studies. Primary outcomes were subsequent VFFs, while secondary outcomes were further nVFFs. The outcome of refracture within ≥ 2 years after the index fracture was measured as (i) rate, expressed per 100 person-years (PYs), and (ii) risk, expressed in percentage.

RESULTS

Forty RCTs met our inclusion criteria, ranging from medium to high quality. Among untreated patients with prior VFFs, the rate of subsequent VFFs and nVFFs was 12 [95% confidence interval (CI) 9-16] and 6 (95% CI 5-8%) per 100 PYs, respectively. The higher the number of previous VFFs, the higher the incidence. Moreover, the risk of VFFs and nVFFs increased within 2 (16.6% and 8%) and 4 years (35.1% and 17.4%) based on the index VFF.

CONCLUSION

The highest risk of subsequent VFFs or nVFFs was already detected within 2 years following the initial VFF. Thus, prompt interventions should be designed to improve the detection and treatment of VFFs, aiming to reduce the risk of future FFs and properly implement secondary preventive measures.

Follow-up Bone Mineral Density Testing: 2023 Official Positions of the International Society for Clinical Densitometry

Dual-energy X-ray absorptiometry (DXA) is the gold standard method for measuring bone mineral density (BMD) which is most strongly associated with fracture risk. BMD is therefore the basis for the World Health Organization's densitometric definition of osteoporosis. The International Society for Clinical Densitometry (ISCD) promotes best densitometry practices and its official positions reflect critical review of current evidence by domain experts. This document reports new official positions regarding follow-up DXA examinations based on a systematic review of literature published through December 2022. Adoption of official positions requires consensus agreement from an expert panel following a modified RAND protocol. Unless explicitly altered by the new position statements, prior ISCD official positions remain in force. This update reflects increased consideration of the clinical context prompting repeat examination. Follow-up DXA should be performed with pre-defined objectives when the results would have an impact on patient management. Testing intervals should be individualized according to the patient's age, sex, fracture risk and treatment history. Incident fractures and therapeutic approach are key considerations. Appropriately ordered and interpreted follow-up DXA examinations support diagnostic and therapeutic decision making, thereby contributing to excellent clinical care. Future research should address the complementary roles of clinical findings, imaging and laboratory testing to guide management.

Pharmacologic Treatment of Primary Osteoporosis or Low Bone Mass to Prevent Fractures in Adults: A Living Clinical Guideline From the American College of Physicians

DESCRIPTION

This guideline updates the 2017 American College of Physicians (ACP) recommendations on pharmacologic treatment of primary osteoporosis or low bone mass to prevent fractures in adults.

METHODS

The ACP Clinical Guidelines Committee based these recommendations on an updated systematic review of evidence and graded them using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system.

AUDIENCE AND PATIENT POPULATION

The audience for this guideline includes all clinicians. The patient population includes adults with primary osteoporosis or low bone mass.

RECOMMENDATION 1A

ACP recommends that clinicians use bisphosphonates for initial pharmacologic treatment to reduce the risk of fractures in postmenopausal females diagnosed with primary osteoporosis (strong recommendation; high-certainty evidence).

RECOMMENDATION 1B

ACP suggests that clinicians use bisphosphonates for initial pharmacologic treatment to reduce the risk of fractures in males diagnosed with primary osteoporosis (conditional recommendation; low-certainty evidence).

RECOMMENDATION 2A

ACP suggests that clinicians use the RANK ligand inhibitor (denosumab) as a second-line pharmacologic treatment to reduce the risk of fractures in postmenopausal females diagnosed with primary osteoporosis who have contraindications to or experience adverse effects of bisphosphonates (conditional recommendation; moderate-certainty evidence).

RECOMMENDATION 2B

ACP suggests that clinicians use the RANK ligand inhibitor (denosumab) as a second-line pharmacologic treatment to reduce the risk of fractures in males diagnosed with primary osteoporosis who have contraindications to or experience adverse effects of bisphosphonates (conditional recommendation; low-certainty evidence).

RECOMMENDATION 3

ACP suggests that clinicians use the sclerostin inhibitor (romosozumab, moderate-certainty evidence) or recombinant PTH (teriparatide, low-certainty evidence), followed by a bisphosphonate, to reduce the risk of fractures only in females with primary osteoporosis with very high risk of fracture (conditional recommendation).

RECOMMENDATION 4

ACP suggests that clinicians take an individualized approach regarding whether to start pharmacologic treatment with a bisphosphonate in females over the age of 65 with low bone mass (osteopenia) to reduce the risk of fractures (conditional recommendation; low-certainty evidence).

Effectiveness and Safety of Treatments to Prevent Fractures in People With Low Bone Mass or Primary Osteoporosis: A Living Systematic Review and Network Meta-analysis for the American College of Physicians

BACKGROUND

The prevalence of osteoporosis is increasing in the United States.

PURPOSE

To evaluate low bone mass and osteoporosis treatments to prevent fractures.

DATA SOURCES

Ovid MEDLINE ALL, Ovid Evidence Based Medicine Reviews: Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and ClinicalTrials.gov from 2014 through February 2022.

STUDY SELECTION

Adults receiving eligible interventions for low bone mass or osteoporosis. Randomized controlled trials (RCTs) for fracture outcomes, and RCTs and large observational studies (n ≥1000) for harms.

DATA EXTRACTION

Abstracted by 1 reviewer and verified by a second. Independent, dual assessments of risk of bias and certainty of evidence (CoE).

DATA SYNTHESIS

We included 34 RCTs (in 100 publications) and 36 observational studies. Bisphosphonates and denosumab reduced hip, clinical and radiographic vertebral, and other clinical fractures in postmenopausal females with osteoporosis (moderate to high CoE). Bisphosphonates for 36 months or more may increase the risk for atypical femoral fractures (AFFs) and osteonecrosis of the jaw (ONJ), but the absolute risks were low. Abaloparatide and teriparatide reduced clinical and radiographic vertebral fractures but increased the risk for withdrawals due to adverse events (WAEs; moderate to high CoE). Raloxifene and bazedoxifene for 36 months or more reduced radiographic vertebral but not clinical fractures (low to moderate CoE). Abaloparatide, teriparatide, and sequential romosozumab, then alendronate, may be more effective than bisphosphonates in reducing clinical fractures for 17 to 24 months in older postmenopausal females at very high fracture risk (low to moderate CoE). Bisphosphonates may reduce clinical fractures in older females with low bone mass (low CoE) and radiographic vertebral fractures in males with osteoporosis (low to moderate CoE).

LIMITATION

Few studies examined participants with low bone mass, males, or Black-identifying persons, sequential therapy, or treatment beyond 3 years.

CONCLUSION

Bisphosphonates, denosumab, abaloparatide, teriparatide, and romosozumab, followed by alendronate, reduce clinical fractures in postmenopausal females with osteoporosis. Abaloparatide and teriparatide increased WAEs; longer duration bisphosphonate use may increase AFF and ONJ risk though these events were rare.

PRIMARY FUNDING SOURCE

American College of Physicians. (PROSPERO: CRD42021236220).

Effect of weekly teriparatide injections on osteoporotic fracture healing: protocol for a double-blind, randomised controlled trial

INTRODUCTION

Both animal studies and clinical trials have shown that daily parathyroid hormone administration promotes bone fracture healing. We previously found that weekly injections of the recombinant human parathyroid hormone teriparatide at a dosage of 20 μg/kg promoted tibial fracture healing to the same extent as daily injections of teriparatide at a dosage of 10 μg/kg in a rodent model. However, the effect of weekly teriparatide administration on human fracture healing is unreported. This protocol describes a randomised controlled clinical trial designed to evaluate whether weekly administration of teriparatide accelerates fracture repair in humans.

METHODS AND ANALYSIS

This single-centre, double-blind, randomised controlled trial will be conducted in Peking University Third Hospital. Eligible patients with Colles' fracture incurred within 48 hours will be randomly divided into two groups (n=40 per group) that will receive 14 weekly subcutaneous injections of either saline or teriparatide (40 μg/week). The primary outcome will be the time taken to achieve radiographic healing, as assessed using the modified radiographic union scale for tibial fractures. The secondary outcomes will be functional assessments, including the self-administered Patient-Rated Wrist Evaluation questionnaire, grip strength and rate of fracture non-union.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Peking University Third Hospital Medical Science Research Ethics Committee (M2020207). The findings will be disseminated in peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT04473989: protocol version: 1.

Genomic Medicine: Lessons Learned From Monogenic and Complex Bone Disorders

Current genetic studies of monogenic and complex bone diseases have broadened our understanding of disease pathophysiology, highlighting the need for medical interventions and treatments tailored to the characteristics of patients. As genomic research progresses, novel insights into the molecular mechanisms are starting to provide support to clinical decision-making; now offering ample opportunities for disease screening, diagnosis, prognosis and treatment. Drug targets holding mechanisms with genetic support are more likely to be successful. Therefore, implementing genetic information to the drug development process and a molecular redefinition of skeletal disease can help overcoming current shortcomings in pharmaceutical research, including failed attempts and appalling costs. This review summarizes the achievements of genetic studies in the bone field and their application to clinical care, illustrating the imminent advent of the genomic medicine era.

Effects of treatment interruption due to patient convenience on treatment of once a week teriparatide

Objectives

Once-weekly teriparatide (W-TPTD) is an effective drug for patients with osteoporosis; however, some patients discontinue W-TPTD owing to its adverse drug reactions (ADRs). Sequential treatment with W-TPTD and antiresorptive therapy may be effective in treating such patients. In this study, we evaluate the efficacy of this sequential treatment regimen.

Methods

This retrospective study was conducted at a single institution in Japan. The target subjects were patients with osteoporosis who started W-TPTD treatment. The subjects who received W-TPTD for 6 months or more were divided into 3 groups: TTT (W-TPTD for 18 months); TBT (sequential treatment of W-TPTD/bisphosphonates/W-TPTD; each for 6 months); and TET (sequential treatment of W-TPTD/elcatonin/W-TPTD, each for 6 months) groups. The efficacy endpoints were bone mineral densities (BMD) in the lumbar spine and femur.

Results

Lumbar spine BMD in group TBT increased significantly by 1.6% (P = 0.023), 2.9% (P = 0.001), and 4.4% (P < 0.001) after 6, 12, and 18 months, respectively, compared with baseline values. In group TET, it increased by 2.1%, (P = 0.001), 1.3% (P = 0.066), and 3.0% (P = 0.015) after 6, 12, and 18 months, respectively. A significant increase was observed only after 6 and 18 months. In group TTT, it increased significantly by 3.3% (P = 0.023), 5.1% (P = 0.019), and 7.1% (P = 0.010) after 6, 12, and 18 months, respectively. However, no significant difference in total hip BMD was observed among all three groups. No serious ADRs were reported.

Conclusion

In patients who discontinue treatment with W-TPTD due to ADRs, sequential treatment with W-TPTD and antiresorptive therapy would be beneficial.

No impact of anti-Rank ligand and PTH analogs on cardiovascular risk in postmenopausal osteoporosis: a systematic literature review and meta-analysis

The mutual effects of drugs used in osteoporosis and cardiovascular diseases are a point of interest. A literature review and meta-analysis were conducted to address the impact of PTH analogs and anti-Rank ligand on cardiovascular events and overall mortality in individuals with idiopathic osteoporosis; these treatments do not appear to have any effect.

INTRODUCTION

Two meta-analyses have been conducted to explore the cardiovascular effects of bisphosphonates. There is no review for other osteoporosis treatments. A literature review and meta-analysis were conducted to address the impact of PTH analogs and anti-Rank ligand on cardiovascular events and overall mortality in individuals with idiopathic osteoporosis.

METHODS

A systematic review was conducted in December 2017 in the PubMed, Embase, and Cochrane databases and updated on PubMed in July 2019, selecting trials with a treatment and a control group. We also conducted a search for abstracts of the French Rheumatology Society, American College of Rheumatology, and European League Against Rheumatism's annual meetings over the past 4 years. The main endpoint was the occurrence of cardiovascular events; the secondary was mortality (all causes).

RESULTS

Of the 2782 reports initially found, 16 articles were used for the meta-analysis (6 for the anti-Rank ligand and 10 for the PTH analog group). After meta-analysis, there was no significant difference between the placebo group and the anti-Rank ligand group for overall mortality (p = 0.13), the combined endpoint (overall mortality, coronary artery disease, and stroke; p 0.77), and the individual risk of coronary artery disease (p 0.53), arrhythmia (p 0.95), and stroke (p 0.62). After meta-analysis, there was no significant difference between the placebo group and the PTH analogs group for overall mortality (p 0.77), the combined endpoint (p = 0.95), and the individual risk of coronary artery disease (p = 0.74), arrhythmia (p = 0.28), and stroke (p = 0.61).

CONCLUSIONS

The anti-Rank ligand and PTH analogs have no impact on cardiovascular risk and overall mortality in idiopathic osteoporosis. To better answer the question whether these treatments can reduce the long-term cardiovascular risk, further comparative studies with longer duration are required.

Effect of medications on prevention of secondary osteoporotic vertebral compression fracture, non-vertebral fracture, and discontinuation due to adverse events: a meta-analysis of randomized controlled trials

BACKGROUND

Bone loss with aging and menopause increases the risk of fragile vertebral fracture, osteoporotic vertebral compression fracture (OVCF). The fracture causes severe pain, impedes respiratory function, lower the quality of life, and increases the risk of new fractures and deaths. Various medications have been prescribed to prevent a secondary fracture, but few study summarized their effects. Therefore, we investigated their effects on preventing subsequent OVCF via meta-analyses of randomized controlled trials.

METHODS

Electronic databases, including MEDLINE, EMBASE, CENTRAL, and Web of Science were searched for published randomized controlled trials from June 2015 to June 2019. The trials that recruited participants with at least one OVCF were included. We assessed the risk of bias of every study, estimated relative risk ratio of secondary OVCF, non-vertebral fracture, gastrointestinal complaints and discontinuation due to adverse events. Finally, we evaluated the quality of evidence.

RESULTS

Forty-one articles were included. Moderate to high quality evidence proved the effectiveness of zoledronate (Relative Risk, RR: 0.34; 95% CI, 0.17-0.69, p = 0.003), alendronate (RR: 0.54; 95% CI: 0.43-0.68; p < 0.0001), risedronate (RR: 0.61; 95% CI: 0.51-0.73; p < 0.0001), etidronate (RR, 0.50; 95% CI, 0.29-0.87, p < 0.01), ibandronate (RR: 0.52; 95% CI: 0.38-0.71; p < 0.0001), parathyroid hormone (RR: 0.31; 95% CI: 0.23-0.41; p < 0.0001), denosumab (RR, 0.41; 95% CI, 0.29-0.57; p < 0.0001) and selective estrogen receptor modulators (Raloxifene, RR: 0.58; 95% CI: 0.44-0.76; p < 0.0001; Bazedoxifene, RR: 0.66; 95% CI: 0.53-0.82; p = 0.0002) in preventing secondary fractures. Moderate quality evidence proved romosozumab had better effect than alendronate (Romosozumab vs. alendronate, RR: 0.64; 95% CI: 0.49-0.84; p = 0.001) and high quality evidence proved that teriparatide had better effect than risedronate (risedronate vs. teriparatide, RR: 1.98; 95% CI: 1.44-2.70; p < 0.0001).

CONCLUSION

Zoledronate, alendronate, risedronate, etidronate, ibandronate, parathyroid hormone, denosumab and selective estrogen receptor modulators had significant secondary prevention effects on OVCF. Moderate quality evidence proved romosozumab had better effect than alendronate. High quality evidence proved PTH had better effect than risedronate, but with higher risk of adverse events.

Change in Bone Density and Reduction in Fracture Risk: A Meta-Regression of Published Trials

Meta-analyses conducted >15 years ago reported that improvements in bone mineral density (BMD) were associated with reduction in vertebral and nonvertebral fractures in osteoporosis trials. Numerous studies have been conducted since then, incorporating new therapies with different mechanisms of action and enrolling many more subjects. To extend these prior analyses, we conducted a meta-regression of 38 placebo-controlled trials of 19 therapeutic agents to determine the association between improvements in BMD and reductions in fracture risk. We used a linear model to examine the relationship between mean percent difference in BMD change between treatment and placebo groups and the logarithm of the relative risk. We found that greater improvements in BMD were strongly associated with greater reductions in vertebral and hip fractures but not nonvertebral fractures. For vertebral fracture, the r² values for total hip, femoral neck, and lumbar spine BMD change were 0.56, 0.54, and 0.63, respectively (p ≤ 0.0002). For a 2% or 6% improvement in total hip BMD, we might expect a 28% or 66% reduction, respectively, in vertebral fracture risk. For hip fracture, the r² values for total hip, femoral neck, and lumbar spine BMD change were 0.48 (p = 0.01), 0.42 (p = 0.02), and 0.22 (ns), respectively. For a 2% or 6% improvement in total hip BMD, we might expect a 16% or 40% reduction in hip fracture risk. In conclusion, our results extend prior observations that larger improvements in dual-energy X-ray absorptiometry (DXA)-based BMD are associated with greater reductions in fracture risk, particularly for vertebral and hip fractures. Although these results cannot be directly applied to predict the treatment benefit in an individual patient, they provide compelling evidence that improvements in BMD with osteoporosis therapies may be useful surrogate endpoints for fracture in trials of new therapeutic agents. © 2019 American Society for Bone and Mineral Research.

Sclerostin Antibody Augments the Anabolic Bone Formation Response in a Mouse Model of Mechanical Tibial Loading

Decreased activity or expression of sclerostin, an endogenous inhibitor of Wnt/β-catenin signaling, results in increased bone formation and mass. Antibodies targeting and neutralizing sclerostin (Scl-Ab) have been shown to increase bone mass and reduce fracture risk. Sclerostin is also important in modulating the response of bone to changes in its biomechanical environment. However, the effects of Scl-Ab on mechanotransduction are unclear, and it was speculated that the loading response may be altered for individuals receiving Scl-Ab therapy. To address this, we carried out a 2-week study of tibial cyclic compressive loading on C57Bl/6 mice treated with vehicle or 100 mg/kg/wk Scl-Ab. Increases in bone volume, density, and dynamic bone formation were found with loading, and the anabolic response was further increased by the combination of load and Scl-Ab. To investigate the underlying mechanism, gene profiling by RNA sequencing (RNAseq) was performed on tibias isolated from mice from all four experimental groups. Major alterations in Wnt/β-catenin gene expression were found with tibial loading, however not with Scl-Ab treatment alone. Notably, the combination of load and Scl-Ab elicited a synergistic response from a number of specific Wnt-related and mechanotransduction factors. An unexpected finding was significant upregulation of factors in the Rho GTPase signaling pathway with combination treatment. In summary, combination therapy had a more profound anabolic response than either Scl-Ab or loading treatment alone. The Wnt/β-catenin and Rho GTPase pathways were implicated within bone mechanotransduction and support the concept that bone mechanotransduction is likely to encompass a number of interconnected signaling pathways. © 2017 American Society for Bone and Mineral Research.

Influence of Dosing Interval and Administration on the Bone Metabolism, Skeletal Effects, and Clinical Efficacy of Parathyroid Hormone in Treating Osteoporosis: A Narrative Review

Recombinant human parathyroid hormone (PTH) is the key anabolic agent used for preventing fracture in postmenopausal women with osteoporosis. In bone metabolism, PTH signaling is mediated through a G protein–coupled receptor that affects various post‐receptor signaling pathways. Results of preclinical and clinical studies have shown that PTH improves both the structure and strength of bone tissue. Once daily subcutaneous injection of the PTH fragment, teriparatide (PTH [1‐34]), is the most commonly recommended formulation and dosing strategy in clinical practice. However, other dosing intervals, formulations, and routes have been investigated in preclinical and clinical studies. In particular, once‐weekly and cyclical administration have been investigated mainly as a means of reducing the high direct costs of treatment. In preclinical studies, bone formation/resorption markers, bone mineral density measurements, and histomorphometric parameters improved with both once‐daily and once‐weekly administration. However, the magnitude and duration of such improvements were generally greater with once‐daily PTH administration. In clinical studies, reductions in fracture incidence were also noted with both once‐daily and once‐weekly PTH administration, although improvements in nonvertebral fractures are less evident with once‐weekly administration. This narrative review details the differences between PTH formulation and dosing strategies in relation to preclinical and clinical efficacy/safety parameters, although it should be stressed that no head‐to‐head studies allow direct comparisons. This review also seeks to outline practical considerations involved with PTH prescribing and new directions in research regarding routes of administration. © 2017 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Teriparatide as a systemic treatment for lower extremity nonunion fractures: a case series

OBJECTIVE

To investigate the effect of teriparatide (parathyroid hormone [1-34]) on the healing of long bone nonunion fractures.

METHODS

We performed a retrospective chart review of patients with fracture nonunion, aged 10 to 99 years who were treated with teriparatide at the Children's Hospital of Philadelphia or the Hospital of the University of Pennsylvania between November 2002 and January 2013. The primary endpoints were radiographic evidence of callus formation and fracture union, ability to bear weight without affected limb limp, and normal range of motion and strength.

RESULTS

Six patients aged 19 to 64 years with tibial or femoral fractures that had not healed for 3 to 36 months were treated with teriparatide 20 μg/day. Accelerated healing of fracture nonunion was confirmed in 5 of 6 patients with time to complete union of 3 to 9 months. The shortest time to recovery was observed in younger patients without comorbidities. Treatment was well tolerated.

CONCLUSION

Teriparatide is a promising treatment for nonunion fractures, but its response depends on associated comorbidities. The potential benefit of teriparatide as an adjunct to treat nonunion justifies randomized placebo-controlled trials to determine its efficacy and safety in broader populations.

[Novel anti-osteoporotic drugs on the horizon]

In recent years the great progress in knowledge on bone cell biology has allowed identification of molecular structures that can be targeted with pinpoint precision (druggable targets). Osteoclasts are regulated via the RANK-RANK-ligand (RANKL) signaling pathway and osteoblasts via the Wnt signaling pathway, both of which can be influenced for therapeutic measures. As a result the number of (functional) osteoclasts can be decreased or the genesis of osteoblasts can be increased and bone resorption is inhibited or bone formation is enhanced, respectively. Osteoclasts degrade collagen through cathepsin K and inactivation of this enzyme stabilizes the bone matrix; however, as osteoclasts are still able to maintain a stimulatory cross-talk with osteoblasts, formation of new bone will not be reduced. Parathyroid hormone-related protein plays a role in endochondral ossification and a synthetic analogue of this protein may have potent bone anabolic activity; however, the use of such new and highly efficient therapeutic principles comes with new questions and uncertainties on the sequence of therapies, duration of therapy, long-term side effects, undesired activation of metabolic pathways and effectiveness in comparison to other strategies of fracture prevention.

Novel therapies for osteoporosis

Since the identification of osteoporosis as a major health issue in aging populations and the subsequent development of the first treatment modalities for its management, considerable progress has been made in our understanding of the mechanisms controlling bone turnover and disease pathophysiology, thus enabling the pinpointing of new targets for intervention. This progress, along with advances in biotechnology, has rendered possible the development of ever more sophisticated treatments employing novel mechanisms of action. Denosumab, a monoclonal antibody against RANKL, approved for the treatment of postmenopausal and male osteoporosis, significantly and continuously increases bone mineral density (BMD) and maintains a low risk of vertebral, non-vertebral, and hip fractures for up to 8 years. Currently available combinations of estrogens with selective estrogen receptor modulators moderately increase BMD without causing the extra-skeletal adverse effects of each compound alone. The cathepsin K inhibitor odanacatib has recently been shown to decrease vertebral, non-vertebral, and hip fracture rates and is nearing approval. Romosozumab, an anti-sclerosin antibody, and abaloparatide, a PTH-related peptide analog, are at present in advanced stages of clinical evaluation, so far demonstrating efficaciousness together with a favorable safety profile. Several other agents are currently in earlier clinical and preclinical phases of development, including dickkopf-1 antagonists, activin A antagonists, β-arrestin analogs, calcilytics, and Src tyrosine kinase inhibitors.

Efficacy of weekly teriparatide does not vary by baseline fracture probability calculated using FRAX

The aim of this study was to determine the efficacy of once-weekly teriparatide as a function of baseline fracture risk. Treatment with once-weekly teriparatide was associated with a statistically significant 79 % decrease in vertebral fractures, and in the cohort as a whole, efficacy was not related to baseline fracture risk.

INTRODUCTION

Previous studies have suggested that the efficacy of some interventions may be greater in the segment of the population at highest fracture risk as assessed by the FRAX® algorithms. The aim of the present study was to determine whether the antifracture efficacy of weekly teriparatide was dependent on the magnitude of fracture risk.

METHODS

Baseline fracture probabilities (using FRAX) were computed from the primary data of a phase 3 study (TOWER) of the effects of weekly teriparatide in 542 men and postmenopausal women with osteoporosis. The outcome variable comprised morphometric vertebral fractures. Interactions between fracture probability and efficacy were explored by Poisson regression.

RESULTS

The 10-year probability of major osteoporotic fractures (without BMD) ranged from 7.2 to 42.2 %. FRAX-based hip fracture probabilities ranged from 0.9 to 29.3 %. Treatment with teriparatide was associated with a 79 % (95 % CI 52-91 %) decrease in vertebral fractures assessed by semiquantitative morphometry. Relative risk reductions for the effect of teriparatide on the fracture outcome did not change significantly across the range of fracture probabilities (p = 0.28). In a subgroup analysis of 346 (64 %) participants who had FRAX probabilities calculated with the inclusion of BMD, there was a small but significant interaction (p = 0.028) between efficacy and baseline fracture probability such that high fracture probabilities were associated with lower efficacy.

CONCLUSION

Weekly teriparatide significantly decreased the risk of morphometric vertebral fractures in men and postmenopausal women with osteoporosis. Overall, the efficacy of teriparatide was not dependent on the level of fracture risk assessed by FRAX in the cohort as a whole.

Novel approaches to the treatment of osteoporosis

Despite the availability of efficacious treatments for fracture reduction in patients with osteoporosis, there are still unmet needs requiring a broader range of therapeutics. In particular, agents that are capable of replacing already lost bone and that also drastically reduce the risk of non-vertebral fractures are needed. Studies of rare bone diseases in humans and animal genetics have identified targets in bone cells for the development of therapies for osteoporosis with novel mechanisms of action. Here, we review these new developments, with emphasis on inhibitors of cathepsin K in osteoclasts and sclerostin in osteocytes, which are currently studied in phase 3 clinical trials.

Efficacy and safety of currently marketed anti-osteoporosis medications

During the past 2 decades, many interventions were proven effective in the management of postmenopausal osteoporosis. The objective of an anti-osteoporosis treatment is to reduce fracture rates, ideally at all skeletal sites (i.e. spine, hip, and other non-spine). The armamentarium against osteoporosis includes anti-resorptive agents (i.e. bisphosphonates, selective estrogen receptor modulators and denosumab), bone-forming agents (i.e. peptides from the parathyroid hormone family) and one agent with a dual mechanism of action (i.e. strontium ranelate). All these medications combine antifracture efficacy with a reasonable benefit/risk profile. However, the choice of a particular chemical entity, in one individual patient is based on the knowledge and expertise of the physician. Prioritization of drugs should be based on the individual profile of the patient, the severity of osteoporosis and the specific contraindications, warnings and precautions of use of the various available medications.