Cancel the denosumab holiday

Treatment of Bisphosphonate-Associated Atypical Femur Fracture With a Combination of Teriparatide and a Novel Surgical Technique

Background/Objective

Atypical femur fractures (AFFs) caused by long-term bisphosphonate use are associated with high rates of delayed healing and nonunion.

Case Report

A 64-year-old woman with osteopenia on alendronate for 15 years sustained a displaced left AFF following a fall from standing height. Imaging showed an acute displaced transverse diaphyseal left femur fracture with lateral cortical thickening and beaking. She underwent an open reduction and internal fixation with insertion of a cephalomedullary nail placed in compression mode, utilizing a novel technique involving intraoperative removal of the endosteal hypertrophied cortical bone at the fracture site. Alendronate was stopped and teriparatide was initiated postoperatively. Radiographs at 3.5 months postsurgery showed evidence of normal fracture union with mature callus formation.

Discussion

AFFs caused by prolonged bisphosphonate use have a high rate of delayed healing and nonunion due to abnormal bone remodeling. Use of teriparatide postoperatively has been shown to reduce healing time in small observational studies in surgically treated patients. Our case demonstrates an expedited healing time of 3.5 months using teriparatide combined with a novel surgical technique involving removal of a portion of the abnormally remodeled bone and placement of an intramedullary nail in compression mode.

Conclusion

Our case demonstrates an expedited healing time of 3.5 months compared to the average reported healing time for AFF of 10.7 months, supporting the use of the combination of teriparatide and a novel surgical technique.

The use of denosumab in osteoporosis - an update on efficacy and drug safety

INTRODUCTION

Denosumab (Prolia) is a fully human monoclonal antibody against the receptor activator of the nuclear factor kappaB ligand. It is a potent antiresorptive agent that reduces osteoclastogenesis.

AREAS COVERED

Denosumab has been shown to improve bone mineral density and reduce the incidence of new fractures in postmenopausal women and men. It is also used in the treatment of glucocorticoid-induced osteoporosis, as well as for the prevention of bone loss and reduction of fracture risk in men receiving androgen deprivation therapy for non-metastatic prostate cancer and women receiving adjuvant aromatase inhibitor therapy for breast cancer. Initial safety concerns included infections, cancer, skin reactions, cardiovascular disease, hypocalcemia, osteonecrosis of the jaw, and atypical femur fractures; however, further study and experience provide reassurance on these issues. Anecdotal reports have raised concerns about an increased risk of multiple vertebral fractures following discontinuation of denosumab.

EXPERT OPINION

Although bisphosphonates are often selected as initial therapy for osteoporosis, denosumab may be an appropriate initial therapy in patients at high risk for fracture, including older patients who have difficulty with the dosing requirements of oral bisphosphonates, as well as patients who are intolerant of, unresponsive to, or have contraindications to other therapies. Additional data is needed to address questions regarding treatment duration and discontinuation.

Management of RANKL-mediated Disorders With Denosumab in Children and Adolescents: A Global Expert Guidance Document

CONTEXT

Denosumab is an effective treatment for many receptor activator of nuclear factor kappa-B ligand (RANKL)-mediated disorders but there are potential safety considerations and limited data to guide its use in children and adolescents.

OBJECTIVE

This document seeks to summarize the evidence and provide expert opinion on safe and appropriate use of denosumab in pediatric RANKL-mediated disorders.

PARTICIPANTS

Ten experts in pediatric bone and mineral medicine from 6 countries with experience in the use of denosumab participated in the creation of this document.

EVIDENCE

Data were sourced from the published literature, primarily consisting of case reports/series and review articles because of the lack of higher level evidence. Expert opinion of the authors was used substantially when no published data were available.

CONCLUSION

Denosumab is an effective treatment for RANKL-mediated disorders in children and adolescents but is often not curative and, in some cases, is best used in conjunction with surgical or other medical treatments. Careful multidisciplinary planning is required to define the goals of treatment and expert oversight needed to manage the risk of mineral abnormalities. Substantive, collaborative research efforts are needed to determine optimal treatment regimens and minimize risks.

Comparison of bone mineral density of osteoporotic and osteopenia menopausal women treated with oral bisphosphonates before stopping the treatment and 1 year after drug holiday period

BACKGROUND

Osteoporosis is a skeletal and bone disorder characterized by bone fractures and decreased bone mineral density (BMD). Bisphosphonates have a great tendency to bind to minerals, and their long-term use can increase the risk of bone fragility in patients. Stopping bisphosphonates after a period of time is called a drug holiday (DH). Recent evidence has shown that patients' BMD may decrease again during DH. However, few studies have been done in this regard. In the present study, we compared the BMD of postmenopausal women during bisphosphonates treatment and 1 year after DH.

MATERIAL AND METHODS

A total of 202 patients were selected with osteopenia (n = 95) and osteoporosis (n = 107); they had been treated with alendronate for 5 years (a rheumatologist confirmed the diagnosis of osteopenia and osteoporosis) and had undergone DH for 1 year. At the arrival of all patients, BMD was checked with the DXA (dual-energy X-ray absorptiometry) method using the 2007 American Explorer model Hologic device based on the Caucasian race. One year later, patients were reassessed for BMD by the same device.

RESULT

The analysis of femoral neck (FN) and lumbar spine (LS) T-score indices in the osteopenia and the osteoporosis groups showed reduction after DH, and the difference was statistically significant in both groups (p = 0.001). After 1 year of stopping bisphosphonate treatment, the average of FN and LS BMD decreased in both groups (p = 0.001).

CONCLUSION

In general, it can be said that DH can reduce FN and LS T-scores. The results indicated a significant reduction in BMD after the DH period for both the osteoporosis and osteopenia groups in the early months. Also, the effect of DH in osteoporosis patients was more compared to the osteopenia individuals, which could have implications for their treatment approach, and also its effect on bone health. Key Points • The DH can reduce FN and LS T-scores • The BMD reduced after the DH period for both the osteoporosis and osteopenia groups • After 1 year of stopping bisphosphonate treatment, the average of FN and LS BMD decreased in both groups.

Treatment of Osteoporosis after Hip Fracture: Survey of the Korean Hip Society

Purpose

To assess current practice in the treatment of osteoporosis in patients who underwent treatment for hip fracture in South Korea.

Materials and Methods

A survey of 97 members of the Korean Hip Society, orthopedic hip surgeons who administer treatment for hip fractures in South Korea, was conducted. The survey was conducted for assessment of demographic data and perceptions regarding the management of osteoporosis in patients who have undergone treatment for hip fracture. Analysis of the data was performed using descriptive statistical methods.

Results

The majority of participants were between the age of 41 and 50 years, and 74% were practicing in tertiary hospitals. Testing for serum vitamin D levels (82%) was the most commonly performed laboratory test. Calcium and vitamin D were prescribed for more than 80% of patients by 47% and 52% of participants, respectively. Denosumab was the most commonly used first-line treatment option for osteoporosis in hip fracture patients. Bisphosphonate was most often perceived as the cause of atypical femoral fractures, and the most appropriate time for reoperation was postoperative 12 months. Teriparatide was most preferred after cessation of bisphosphonate and only prescribing calcium and vitamin D was most common in high-risk patients for prevention of atypical femoral fracture.

Conclusion

The results of this study that surveyed orthopedic hip surgeons showed that most participants followed the current strategy for management of osteoporosis. Because the end result of osteoporosis is a bone fracture, active involvement of orthopedic surgeons is important in treating this condition.

Cortical thickness adaptation to combined mechanical loading and parathyroid hormone treatments is site specific and synergistic in the mouse tibia model

In this study, we aimed to quantify the localised effects of mechanical loading (ML), low (20 μg/kg/day), moderate (40 μg/kg/day) or high (80 μg/kg/day) dosages of parathyroid hormone (PTH), and combined (PTHML) treatments on cortical bone adaptation in healthy 19-week old female C57BL/6 mice. To this end, we utilise a previously reported image analysis algorithm on μCT data of the mouse tibia published by Sugiyama et al. (2008) to measure changes in cortical area, marrow cavity area and local cortical thickness measures (ΔCt.Ar, ΔMa.Ar, ΔCt.Th respectively), evaluated at two cross-sections within the mouse tibia (proximal-middle (37 %) and middle (50 %)), and are compared to a superposed summation (P + M) of individual treatments to determine the effectiveness of combining treatments in vivo. ΔCt.Ar analysis revealed a non-linear, synergistic interactions between PTH and ML in the 37 % cross-section that saturates at higher PTH dosages, whereas the 50 % cross-section experiences an approximately linear, additive adaptation response. This coincided with an increase in ΔMa.Ar (indicating resorption of the endosteal surface), which was only counteracted by combined high dose PTH with ML in the middle cross-section. Regional analysis of ΔCt.Th changes reveal localised cortical thinning in response to low dose PTH treatment in the posteromedial region of the middle cross-section, signifying that PTH does not provide a homogeneous adaptation response around the cortical perimeter. We observe a synergistic response in the proximal-middle cross-section, with regions of compressive strain experiencing the greatest adaptation response to PTHML treatments, (peak ΔCt.Th of 189.32, 213.78 and 239.30 μm for low, moderate and high PTHML groups respectively). In contrast, PTHML treatments in the middle cross-section show a similar response to the superposed P + M group, with the exception of the combined high dose PTHML treatment which shows a synergistic interaction. These analyses suggest that, in mice, adding mechanical loading to PTH treatments leads to region specific bone responses; synergism of PTHML is only achieved in some regions experiencing high loading, while other regions respond additively to this combined treatment.

Reduced osteoprotegerin expression by osteocytes may contribute to rebound resorption after denosumab discontinuation

Denosumab is an anti-RANKL Ab that potently suppresses bone resorption, increases bone mass, and reduces fracture risk. Discontinuation of denosumab causes rapid rebound bone resorption and bone loss, but the molecular mechanisms are unclear. We generated humanized RANKL mice and treated them with denosumab to examine the cellular and molecular conditions associated with rebound resorption. Denosumab potently suppressed both osteoclast and osteoblast numbers in cancellous bone in humanized RANKL mice. The decrease in osteoclast number was not associated with changes in osteoclast progenitors in bone marrow. Long-term, but not short-term, denosumab administration reduced osteoprotegerin (OPG) mRNA in bone. Localization of OPG expression revealed that OPG mRNA is produced by a subpopulation of osteocytes. Long-term denosumab administration reduced osteocyte OPG mRNA, suggesting that OPG expression declines as osteocytes age. Consistent with this, osteocyte expression of OPG was more prevalent near the surface of cortical bone in humans and mice. These results suggest that new osteocytes are an important source of OPG in remodeling bone and that suppression of remodeling reduces OPG abundance by reducing new osteocyte formation. The lack of new osteocytes and the OPG they produce may contribute to rebound resorption after denosumab discontinuation.

Risk factors for poor response to denosumab treatment in Japanese postmenopausal women with osteoporosis

INTRODUCTION

Denosumab has been reported to increase bone mineral density (BMD) and suppress fractures, but poor responders are not uncommon. This study aimed to identify risk factors for poor response to denosumab treatment. This is the first study to explore risk factors for poor response to denosumab.

MATERIALS AND METHODS

This retrospective observational study investigated 227 Japanese postmenopausal women who received denosumab with monitoring of BMD by dual-energy X-ray absorptiometry at 6-month intervals. Risk factors were identified using Cox's proportional hazard modeling. Poor responders were defined as not exceeding the least significant change of BMD from baseline for 3 years.

RESULTS

Mean relative change from baseline for 3 years in lumbar spine (LS)-BMD, femoral neck (FN)-BMD, and total hip (TH)-BMD were 12.6%, 6.8%, and 6.1%, respectively. Numbers of poor responders were 10 in LS-BMD, 47 in FN-BMD, 38 in TH-BMD. Risk factors for poor response were concomitant glucocorticoid use for LS-BMD, low body mass index or initiation at higher BMD for FN-BMD, and pretreatment with bisphosphonates or initiation at higher BMD for TH-BMD.

CONCLUSION

Risk factors for insufficient denosumab effect differed between BMD measurement sites. These results should be taken into consideration when selecting denosumab in clinical practice.

Current use of bone turnover markers in the management of osteoporosis

The adult bone is continuously being remodelled to repair microdamage, preserve bone strength and mechanical competence as well as maintain calcium homeostasis. Bone turnover markers are products of osteoblasts (bone formation markers) and osteoclasts (bone resorption markers) providing a dynamic assessment of remodelling (turnover). Resorption-specific bone turnover markers are typically degradation products of bone collagen molecules (N- [NTX] and C-telopeptide cross-linked type 1 collagen [CTX]), which are released into the circulation and excreted in urine; or enzymatic activities reflecting osteoclastic resorption, tartrate-resistant acid phosphatase [TRACP]. Formation-specific bone turnover markers embrace different osteoblastic activities: type 1 collagen synthesis (Procollagen type I N- propeptide [PINP]), osteoblast enzymes (bone-specific alkaline phosphatase [BALP]), or bone matrix proteins [osteocalcin]. Among individuals not receiving osteoporosis treatment, resorption and formation markers are tightly linked and highly correlated (r= 0.6-0.8). Significant biological variability was reported in the past, but these issues have been greatly improved with automated assays and attention to pre-analytical and analytical factors that are known to influence bone turnover marker levels. Bone turnover markers are not useful in the diagnosis of osteoporosis, the individual prediction of bone loss, fracture, or rare complications, or in the selection of pharmacological treatment. Despite remaining issues with reference intervals and assays harmonization, bone turnover markers have proven to be useful in elucidating the pharmacodynamics and effectiveness of osteoporosis medications in clinical trials. As an alternative to BMD testing, BTMs may be useful to monitor osteoporosis therapies.

Patterns of Osteoporosis Medications Selection after Drug Holiday or Continued Therapy: A Real-World Experience

PURPOSE

Published literature on physicians' preferences and sequential treatment (Rx) patterns of osteoporosis therapy is scarce.

METHODS

A retrospective cohort study of patients who received at least 3 consecutive years of bisphosphonates, denosumab, and/or raloxifene, or at least 18 months of teriparatide for osteoporosis. Data gathering spanned 10 years from October 2007 until September 2016 at a tertiary care center in USA.

RESULTS

12,885 patients were identified based on receiving at least one Rx at any point in time, 1,814 patients were randomly reviewed, and 274 patients met the inclusion criteria. The mean age was 68.8 ± 10.7 years and females represented 90.9%. Primary care physicians constituted 65.7% and rheumatologists 22.6% of the prescribers. Prior to instituting a drug holiday, alendronate was the most common initial Rx (Percentage, mean duration ± standard deviation in years): 69.0%, 5.4±2.4y followed by ibandronate (9.5%, 4.9±2.1y) and raloxifene (9.1%, 5.2±1.6y). Denosumab was the most common second course of Rx accounting for 29.3% of the total of 82 patients who were subsequently prescribed another therapy, followed by alendronate (24.4%) and zoledronate (20.7%). Among patients who were placed on a drug holiday and eventually restarted on an osteoporosis therapy, denosumab was the most common treatment instituted (n=21) accounting for 40% of the total, followed by alendronate (32%) and zoledronate (16%). There was a progressive decline of osteoporosis therapy over the duration of the study.

CONCLUSION

Alendronate was the most common initial therapy. Denosumab was the most common second course of treatment prescribed.

Adverse events associated with bone-directed therapies in patients with cancer

Bone metastatic disease may lead to serious adverse events in patients with cancer. Bone-directed therapies, including bisphosphonates such as pamidronate and zoledronic acid and the human monoclonal antibody denosumab, are currently approved for the prevention of bone-related adverse events. However, despite the benefits of these drugs, they may cause side effects that are mostly associated with dosages and treatment durations. These side effects range from more frequent, mostly mild, and generally self-limited side effects-such as fever, myalgias, arthralgias, and electrolyte imbalances-to less frequent and more severe side effects such as medication-related osteonecrosis of the jaw and atypical femoral fractures. The purpose of this review is to familiarize clinicians with the literature regarding adverse events associated with bone-directed therapies in patients with cancer. It is important to be aware of these possible adverse events and to educate patients about the predisposing factors associated with side effects from bone-directed therapies and the preventive measures necessary to decrease the risk of occurrence.

Multiple idiopathic external cervical root resorption in patient treated continuously with denosumab: a case report

Background

External root resorption is an irreversible loss of dental hard tissue as a result of odontoclastic action. Multiple external cervical root resorptions in permanent teeth are rare. The exact cause of external cervical root resorption is unclear. It is currently well established that RANK/RANKL signaling is essential for osteoclastogenesis and osteoclast-mediated bone resorption. Denosumab is an anti-RANKL antibody used for the treatment of postmenopausal osteoporosis. RANK/RANKL pathway suppression by denosumab is expected to suppress the activity of clastic cells responsible for hard tissue resorption involving both osteoclasts and odontoclasts.

Case presentation

This case report demonstrates aggressive and generalized idiopathic external cervical root resorption that started and advanced during ongoing antiresorptive therapy with the human monoclonal RANKL-blocking antibody denosumab without discontinuation of therapy in a 74-year-old female patient treated for postmenopausal osteoporosis. The extent of resorptive defects was too large and progressively led to fractures of the teeth. The number of teeth involved and the extend of destruction excluded conservative treatment. The affected teeth had to be extracted for functional prosthetic reconstruction.

Conclusions

This finding suggests that treatment with denosumab may be associated with severe and aggressive odontoclastic resorption of multiple dental roots despite an adequate inhibitory effect on osteoclasts in the treatment of osteoporosis. The RANKL-independent pathways of clastic cell formation are likely to be involved in this pathological process.

Denosumab in the Treatment of Osteoporosis: 10 Years Later: A Narrative Review

The fully human monoclonal antibody denosumab was approved for treatment of osteoporosis in 2010 on the basis of its potent antiresorptive activity, which produces clinically meaningful increases in bone mineral density (BMD) and reduces fracture risk at key skeletal sites. At that time, questions remained regarding the long-term safety and efficacy of this receptor activator of nuclear factor kappa-B ligand (RANKL) inhibitor; and with clinical experience, new questions have arisen regarding its optimal use. Here, we examine these questions through the lens of data from the FREEDOM trial program and other studies to determine where denosumab fits in the osteoporosis treatment landscape. Clinical consensus and evidentiary support have grown for denosumab as a highly effective anti-osteoporosis therapy for patients at high risk of fracture. In the 10-year FREEDOM Extension study, denosumab treatment produced progressive incremental increases in BMD, sustained low rates of vertebral fracture, and further reduction in nonvertebral fracture risk without increased risk of infection, cancer, or immunogenicity. There was no evidence that suppression of bone turnover or mineralization was excessive, and rates of osteonecrosis of the jaw (ONJ) and atypical femoral fracture (AFF) were very low. It is now recognized, however, that transitioning to another anti-osteoporosis therapy after denosumab discontinuation is essential to mitigate a transient rebound of bone turnover causing rapid BMD loss and increased risk of multiple vertebral fractures (MVFs). Taken together, the available data show that denosumab has a favorable benefit/risk profile and is a versatile agent for preventing osteoporotic fractures in the short and long term.

Proceedings of the 2021 Santa Fe Bone Symposium: Advances in the Management of Osteoporosis and Metabolic Bone Diseases

The 2021 Virtual Santa Fe Bone Symposium was held August 5-8, with over 300 registered attendees from throughout the USA, and at least 18 other countries. This annual meeting focuses on applying advances in basic science and clinical research to the care of patients with osteoporosis and those with inherited and acquired disorders of bone metabolism. Participants represented a broad range of medical disciplines with an interest in skeletal diseases. These included physicians of many specialties and practice settings, fellows, advanced practice providers, fracture liaison service (FLS) coordinators, clinical researchers, and bone density technologists. There were lectures, case presentations, and panel discussions, all followed by interactive discussions. Breakout sessions included an FLS workshop, Bone Health TeleECHO workshop, special interest groups, meet-and-greet the faculty, and satellite symposia. The agenda covered topics of interest such as strategies for the use of osteoanabolic therapy, prevention of periprosthetic fractures, management of atypical femur fractures, what we know and don't know about vitamin D, advances in the use of dual-energy X-ray absorptiometry in the assessment of skeletal health, controversies and conundrums in osteoporosis care, skeletal health in transgender patients, management of patients with hypophosphatasia and hypophosphatemia, and treat-to-target approaches for managing patients with osteoporosis. The Proceedings of the 2021 Virtual Santa Fe Bone Symposium consists of highlights of each presentation with current strategies for optimizing the care of patients with skeletal disorders.

Interstitial Lung Disease in a Woman with Rheumatoid Arthritis Treated with Denosumab: A Case Report

The present report describes the case of an 84-year-old female Japanese patient with rheumatoid arthritis (RA) who experienced exacerbation of interstitial lung disease (ILD) after denosumab (Dmab) treatment. The onset of RA occurred in 2008, and the patient had been treated with intravenous or subcutaneous injection of tocilizumab (TCZ) since 2009. In July 2013, she experienced a lumbar vertebral fracture and began treatment with 60-mg Dmab injection every 6 months in January 2014. The patient had a history of mild ILD and was evaluated for ILD by chest computed tomography (CT) imaging prior to the start of Dmab use. The vertebral fracture did not recur after the initiation of Dmab treatment, and her osteoporosis was successfully treated. However, she expressed a concern of exacerbations of cough and respiratory discomfort that had occurred since September 2019. The chest CT image in November 2015 showed minor ILD progression, whereas the image in September 2019 showed severe exacerbation of ILD. To treat this exacerbation, 10 mg of methylprednisolone (mPSL) and 2.5 mg of tacrolimus (TAC) were administered, and Dmab was discontinued. The patient was subsequently switched to oral bisphosphonate. The patient's respiratory discomfort and the finding of interstitial lung lesion in CT imaging improved after Dmab discontinuation. This case showed that exacerbation of ILD may occur after Dmab treatment, and physicians should consider the risks of Dmab-related ILD in patients with RA complicated by ILD.

Denosumab-related osteonecrosis of the jaw after tooth extraction and the effects of a short drug holiday in cancer patients: a multicenter retrospective study

Pre-existing inflammation, corticosteroid therapy, periapical periodontitis, longer duration of denosumab therapy, and female sex were significantly associated with an increased risk of denosumab-related osteonecrosis of the jaw after tooth extraction in patients with cancer on oncologic doses of denosumab. A short drug holiday did not protect against this complication.

INTRODUCTION

This study retrospectively investigated the relationship between various risk factors, including brief discontinuation of denosumab, and development of denosumab-related osteonecrosis of the jaw (DRONJ) after tooth extraction in patients with cancer who were receiving oncologic doses of this agent.

METHODS

Data were collected on demographic characteristics, duration of denosumab therapy, whether or not denosumab was discontinued before tooth extraction (drug holiday), duration of discontinuation, presence of pre-existing inflammation, and whether or not additional surgical procedures were performed. Risk factors for DRONJ after tooth extraction were evaluated by univariate and multivariate analyses.

RESULTS

A total of 136 dental extractions were performed in 72 patients (31 men, 41 women) with cancer who were receiving oncologic doses of denosumab. Post-extraction DRONJ was diagnosed in 39 teeth (28.7%) in 25 patients. Tooth extraction was significantly associated with development of DRONJ only in patients with pre-existing inflammation (odds ratio [OR] 243.77), those on corticosteroid therapy (OR 73.50), those with periapical periodontitis (OR 14.13), those who had been taking oncologic doses of denosumab for a longer period (OR 4.69), and in women (OR 1.04). There was no significant difference in the occurrence of DRONJ between patients who had a drug holiday before tooth extraction and those who did not.

CONCLUSIONS

These findings suggest that inflamed teeth should be extracted immediately in patients with cancer who are receiving oncologic doses of denosumab. Drug holidays have no significant impact on the risk of DRONJ.

Multiple vertebral fractures after suspension of denosumab. A series of 56 cases

BACKGROUND

Denosumab is a monoclonal antibody approved for the treatment of postmenopausal osteoporosis. The withdrawal of denosumab produces an abrupt loss of bone mineral density and may cause multiple vertebral fractures (MVF).

OBJECTIVE

The objective of this study is to study the clinical, biochemical, and densitometric characteristics in a large series of postmenopausal women who suffered MVF after denosumab withdrawal. Likewise, we try to identify those factors related to the presence of a greater number of vertebral fractures (VF).

PATIENTS AND METHODS

Fifty-six patients (54 women) who suffered MVF after receiving denosumab at least for three consecutive years and abruptly suspended it. A clinical examination was carried out. Biochemical bone remodelling markers (BBRM) and bone densitometry at the lumbar spine and proximal femur were measured. VF were diagnosed by magnetic resonance imaging MRI, X-ray, or both at dorsal and lumbar spine.

RESULTS

Fifty-six patients presented a total of 192 VF. 41 patients (73.2%) had not previously suffered VF. After discontinuation of the drug, a statistically significant increase in the BBRM was observed. In the multivariate analysis, only the time that denosumab was previously received was associated with the presence of a greater number of VF (P = .04).

CONCLUSIONS

We present the series with the largest number of patients collected to date. 56 patients accumulated 192 new VF. After the suspension of denosumab and the production of MVF, there was an increase in the serum values of the BBRM. The time of denosumab use was the only parameter associated with a greater number of fractures.

Safety of therapy with and withdrawal from denosumab in fibrous dysplasia and McCune-Albright syndrome: an observational study

Denosumab (Dmab) treatment can benefit patients with fibrous dysplasia/McCune-Albright syndrome (FD/MAS) by suppressing the receptor activator of nuclear factor κB ligand (RANKL)-mediated increased bone resorption. However, limited data of two pediatric cases indicate that a rebound phenomenon may occur after withdrawal. Therefore we studied the safety of Dmab discontinuation in FD/MAS. Thirty-seven patients using Dmab, mostly after unsuccessful bisphosphonate (BP) treatment, were included. Health records were screened for pain scores, side effects, and bone turnover markers (BTMs) (calcium, alkaline phosphatase [ALP], procollagen 1 N-terminal propeptide [P1NP], and β-crosslaps [B-CTX, also termed β-C-terminal telopeptide]) during treatment, and for BTMs and clinical rebound effects after withdrawal. BTM levels after withdrawal were compared to pretreatment values. Data were calculated as median (interquartile range [IQR]). BTMs normalized in two-thirds of patients and pain scores decreased significantly during treatment (p = 0.002). One patient (2.7%) developed osteonecrosis of the jaw. Sixteen patients discontinued Dmab treatment after a median of 1.6 years (IQR 1.0 years) because of insufficient effect on pain (n = 10, 63%), side effects (n = 4, 25%), or other reasons (n = 4, 25%). Follow-up posttreatment was 3.2 (2.8) years, wherein no fractures, pain flares, or lesion progression occurred. Calcium remained normal in all but one patient, who had a mild asymptomatic hypercalcemia (2.73 mmol/L) 5 months after discontinuation. ALP passed pretreatment levels in five of 11 patients (46%), increased most after 6 months by 18 (43) U/L, and returned to baseline levels thereafter. P1NP exceeded pretreatment levels in four of nine patients (44%), CTX in eight of nine patients (89%). P1NP rose most after 3 months and stabilized thereafter. CTX showed the highest relative elevation. Patients with high pretreatment levels responding well to Dmab seemed to have the highest rebound. These results suggest beneficial effects of Dmab on pain and BTMs, and show a biochemical but asymptomatic rebound phenomenon after withdrawal in adults with FD/MAS, mainly in case of high pretreatment levels, good response, and multiple injections. Further studies on the safety of Dmab and withdrawal are needed and ongoing. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Cortical Thickness Adaptive Response to Mechanical Loading Depends on Periosteal Position and Varies Linearly With Loading Magnitude

The aim of the current study was to quantify the local effect of mechanical loading on cortical bone formation response at the periosteal surface using previously obtained μCT data from a mouse tibia mechanical loading study. A novel image analysis algorithm was developed to quantify local cortical thickness changes (ΔCt.Th) along the periosteal surface due to different peak loads (0N ≤ F ≤ 12N) applied to right-neurectomised mature female C57BL/6 mice. Furthermore, beam analysis was performed to analyse the local strain distribution including regions of tensile, compressive, and low strain magnitudes. Student's paired t-test showed that ΔCt.Th in the proximal (25%), proximal/middle (37%), and middle (50%) cross-sections (along the z-axis of tibia) is strongly associated with the peak applied loads. These changes are significant in a majority of periosteal positions, in particular those experiencing high compressive or tensile strains. No association between F and ΔCt.Th was found in regions around the neutral axis. For the most distal cross-section (75%), the association of loading magnitude and ΔCt.Th was not as pronounced as the more proximal cross-sections. Also, bone formation responses along the periosteum did not occur in regions of highest compressive and tensile strains predicted by beam theory. This could be due to complex experimental loading conditions which were not explicitly accounted for in the mechanical analysis. Our results show that the bone formation response depends on the load magnitude and the periosteal position. Bone resorption due to the neurectomy of the loaded tibia occurs throughout the entire cross-sectional region for all investigated cortical sections 25, 37, 50, and 75%. For peak applied loads higher than 4 N, compressive and tensile regions show bone formation; however, regions around the neutral axis show constant resorption. The 50% cross-section showed the most regular ΔCt.Th response with increased loading when compared to 25 and 37% cross-sections. Relative thickness gains of approximately 70, 60, and 55% were observed for F = 12 N in the 25, 37, and 50% cross-sections. ΔCt.Th at selected points of the periosteum follow a linear response with increased peak load; no lazy zone was observed at these positions.

Duration of Bisphosphonate Drug Holidays in Osteoporosis Patients: A Narrative Review of the Evidence and Considerations for Decision-Making

Bisphosphonates are first-line therapy for osteoporosis, with alendronate, risedronate, and zoledronate as the main treatments used globally. After one year of therapy, bisphosphonates are retained in bone for extended periods with extended anti-fracture effects after discontinuation. Due to this continued fracture protection and the potential for rare adverse events associated with long-term use (atypical femoral fractures and osteonecrosis of the jaw), a drug holiday of two to three years is recommended for most patients after long-term bisphosphonate therapy. The recommendation for a drug holiday up to three years is derived primarily from extensions of pivotal trials with alendronate and zoledronate and select surrogate marker studies. However, certain factors may modify the duration of bisphosphonate effects on a drug holiday and warrant consideration when determining an appropriate time off-therapy. In this narrative review, we recall what is currently known about drug holidays and discuss what we believe to be the primary considerations and areas for future research regarding drug holiday duration: total bisphosphonate exposure, type of bisphosphonate used, bone mineral density and falls risk, and patient sex and body weight.

Osteoporosis in Men: A Review of an Underestimated Bone Condition

Osteoporosis is called the 'silent disease' because, although it does not give significant symptoms when it is not complicated, can cause fragility fractures, with serious consequences and death. Furthermore, the consequences of osteoporosis have been calculated to weigh heavily on the costs of health systems in all the countries. Osteoporosis is considered a female disease. Actually, the hormonal changes that occur after menopause certainly determine a significant increase in osteoporosis and the risk of fractures in women. However, while there is no doubt that women are more exposed to osteoporosis and fragility fractures, the literature clearly indicates that physicians tend to underestimate the osteoporosis in men. The review of the literature done by the authors shows that osteoporosis and fragility fractures have a high incidence also in men; and, furthermore, the risk of fatal complications in hip fractured men is higher than that for women. The authors report the evidence of the literature on male osteoporosis, dwelling on epidemiology, causes of osteoporosis in men, diagnosis, and treatment. The analysis of the literature shows that male osteoporosis is underscreened, underdiagnosed, and undertreated, both in primary and secondary prevention of fragility fractures.

Denosumab Discontinuation and the Rebound Phenomenon: A Narrative Review

Denosumab is a potent antiresorptive agent that substantially increases bone mineral density and reduces fracture rates at all skeletal sites for as long as it is administered. However, its favorable skeletal effects reverse quickly upon its discontinuation, because of a vast increase of osteoclast number and activity, which leads to a subsequent profound increase of bone turnover above pre-treatment values, a phenomenon commonly described as “rebound phenomenon”. More importantly, most patients experience rapid, profound bone loss due to this burst of bone resorption that may lead in a minority of these patients to occurrence of fractures, especially multiple vertebral fractures. Therefore, subsequent antiresorptive treatment is mandatory, although the optimal regimen is yet to be clarified. In the present review, we outline what is currently known regarding the negative effects of denosumab discontinuation on different aspects of bone status, the factors that may affect them, and strategies to prevent them.

The Effect of Teriparatide for the Treatment of Multiple Spontaneous Clinical Vertebral Fractures after Discontinuation of Denosumab in a Female Patient with Rheumatoid Arthritis: A Case Report

Discontinuation of denosumab is associated with the risk of rebound in bone turnover and rebound-associated spontaneous clinical vertebral fractures. This case report presents an 86-year-old woman with rheumatoid arthritis who experienced rebound-associated spontaneous clinical vertebral fractures at 9 months after denosumab discontinuation. Following 5-year bisphosphonate treatment, the patient had 9 injections of 60-mg denosumab every 6 months. Because of tooth extraction, denosumab treatment was discontinued, and raloxifene was administered. At 9 months after the last denosumab injection, the patient experienced severe low back pain. Magnetic resonance imaging (MRI) and radiograph demonstrated clinical fracture at the fourth lumbar vertebra. MRI performed at 3 months after first fracture showed two additional fractures at the second and third lumbar vertebrae. Teriparatide was administered for management of rebound-associated spontaneous clinical, multiple vertebral fractures. Teriparatide was effective for accelerating the fracture healing and suppressing the occurrence of new fractures. However, 2-year treatment of teriparatide did not have suppressive effect of rebound in bone turnover and general bone loss. This case suggested that teriparatide was effective for suppression of new rebound-associated spontaneous clinical vertebral fractures, but not effective in prevention of general bone loss after denosumab discontinuation.

Reasons for Initiation and Discontinuation of Pharmacological Therapies for Osteoporosis in Veterans with Spinal Cord Injury and Disorders

INTRODUCTION

Medications for osteoporosis have not been reported to reduce fracture rates in patients with spinal cord injury and disorders (SCI/D), yet these medications are still prescribed. Clinical decision-making underscoring the initiation and discontinuation of osteoporosis medications in SCI/D remains poorly understood.

METHODOLOGY

Veterans with a SCI/D with at least one prescription for an osteoporosis medication (bisphosphonate, calcitonin, denosumab, raloxifene, and teriparatide) who received healthcare within Veterans Affairs (VA) from 2005 to 2015 were identified using VA administrative databases. A 10% subsample of Veterans was selected for electronic health record review.

RESULTS

Two hundred and sixty-seven Veterans with 330 prescriptions underwent electronic health record review. Bisphosphonates were the most frequently prescribed medication for osteoporosis (n = 223, 67.6%). Of the 187 Veterans with prescriptions for prevention or treatment of osteoporosis, the primary reason for initiation was Dual Energy X-ray Absorptiometry (DXA) scan with osteopenia or osteoporosis (n = 119, 63.6% of Veterans), primarily at the hip (81.0% of DXAs). The majority (79.0%) of DXAs were "screening tests," with SCI/D being the sole reason for the scan. Fractures (n = 51, 27.3%) and fall risk concerns (n = 29, 15.5%) were other major reasons for initiation. On average, oral bisphosphonates were filled for <3 yr, with medication-related side effects (n = 23, 15.8% of bisphosphonates discontinued), predominately gastrointestinal (n = 17, 73.9% of reported side effects), the most common reason for discontinuation. Drug holidays occurred in 14.3% of 35 oral bisphosphonates used for ≥5 yr. No cases of osteonecrosis of the jaw were found. There was one case of an atypical femoral fracture which could not be confirmed.

CONCLUSIONS

The decision to initiate pharmacological therapies in SCI/D is primarily based on osteopenia or osteoporosis at the hip by screening DXAs. Gastrointestinal side effects are the major reason for discontinuation of oral bisphosphonates. New therapies for osteoporosis in SCI/D are needed.

The safety profile of denosumab in oncology beyond the safety of denosumab as an anti-osteoporotic agent: still more to learn

INTRODUCTION

Initially endorsed as an antiosteoporotic agent, denosumab ‒ human monoclonal antibody inhibiting the receptor activator of nuclear factor kappa-B ligand (RANKL)‒ has currently shown an anticancer potential, rationalizing its exploitation in oncology. A prerequisite for leveraging denosumab in oncology is a favorable safety profile.

AREAS COVERED

The present review provides an overview of the adverse events of denosumab in oncology, with a focus on hypocalcemia, medication-related osteonecrosis of the jaw, atypical femoral fracture(s), post-denosumab vertebral fractures, increased risk of infections, and excess of second primary cancer. Representative studies addressing the safety and efficacy of denosumab compared to bisphosphonates in oncology are summarized. Critical gaps in the literature concerning the safety of denosumab in oncology are highlighted as opposed to plenty of available safety data on denosumab as an antiosteoporotic agent.

EXPERT OPINION

Despite the generally acceptable safety profile of denosumab in oncology, many issues remain unresolved. Further research is mandatory to counteract current challenges, namely: (i) validation of risk factors for adverse events; (ii) elucidation of the pathophysiology of the adverse events in search of actionable molecular pathways; (iii) illumination of the association of denosumab with increased risk of infections and/or second primary cancer; (iv) establishment of optimal diagnostic, and therapeutic protocols.

Denosumab Use as a Predictor Variable for External Cervical Resorption: A Case-Control Study

INTRODUCTION

The objective of this case-control study was to investigate the association between denosumab use and the risk of developing external cervical resorption (ECR).

METHODS

Thirty-three patients ≥45 years old who were diagnosed with ECR were selected. Controls were matched to the cases based on sex and age (±5 years) in a 1:1 ratio. Confounders were classified into systemic factors, including a history of systemic sclerosis, hepatitis B, denosumab use, and bisphosphonate use, or local factors, including a history of traumatic occlusion, periodontal procedures (scaling and root planing and periodontal surgeries), and tooth extraction (excluding third molar extraction). Additionally, the number of remaining teeth in each subject was recorded using panoramic radiographs. The baseline characteristics of the 2 groups, including age, sex, and the number of remaining teeth, were compared using the chi-square and Mann-Whitney U tests. Binary logistic regression was used to determine the possible association between denosumab use and the risk of developing ECR (α < 0.05).

RESULTS

No significant differences in baseline characteristics were observed between the case and control groups (P > .05). After adjusting for systemic and local cofounders, denosumab use was significantly associated with the occurrence of ECR (odds ratio = 7.317; 95% confidence interval, 1.410-37.966; P < .05).

CONCLUSIONS

Based on the binary logistic regression model, denosumab use could significantly predict the risk of developing ECR.

Fracture risk and management of discontinuation of denosumab therapy: a systematic review and position statement by ECTS

CONTEXT

Denosumab discontinuation is characterized by an increase in bone turnover overriding pre-treatment status, a rapid bone loss in the majority and multiple vertebral fractures (VFx) in some patients.

METHODS

A working group of the European Calcified Tissue Society (ECTS) performed an updated systematic review of existing literature on changes of bone turnover, bone mineral density (BMD), and fracture risk after denosumab discontinuation and provided advice on management based on expert opinion.

RESULTS

Important risk factors for multiple VFx following denosumab cessation are prevalent VFx, longer duration off therapy, greater gain in hip BMD during therapy, and greater loss of hip BMD after therapy according to a retrospective analysis of the FREEDOM Extension Study. Case series indicate that prior bisphosphonate therapy mitigates the biochemical rebound phenomenon after denosumab discontinuation, but it is uncertain whether this attenuation prevents BMD loss and fractures. Current evidence indicates partial efficacy of subsequent antiresorptive treatment with results seemingly dependent on duration of denosumab treatment.

CONCLUSIONS

A careful assessment of indications to start denosumab treatment is advised, especially for younger patients. A case for long-term treatment with denosumab can be made for patients at high fracture risk already on denosumab treatment given the favorable efficacy and safety profile. In case of denosumab discontinuation, alternative antiresorptive treatment should be initiated 6 months after the final denosumab injection. Assessment of bone turnover markers may help define the optimal regimen, pending results of ongoing RCTs. Patients having sustained VFx should be offered prompt treatment to reduce high bone turnover.

Are drug holidays a safe option in treatment of osteoporosis? - Insights from an in silico mechanistic PK-PD model of denosumab treatment of postmenopausal osteoporosis

Recent reviews by the clinical bone research community suggest caution with prescription of drug holidays for patients with postmenopausal osteoporosis (PMO) treated with denosumab for an extended period of time. Main reasons for this suggestion are based on the fact that discontinuation of denosumab treatment leads to a relapse of osteoclastic bone resorption and a loss of bone mineral density (BMD) to pre-treatment levels at only 12-28 months. The question remains what is the best treatment option for cases where it is required to discontinue and/or reduce the drug dose and what are the consequences on BMD and bone turnover markers (BTMs). The latter questions are difficult to be addressed using clinical trials alone given the large number of parameter combinations involved to answer this problem. In this paper, we apply a recently developed in silico mechanistic pharmacokinetic-pharmacodynamic (PK-PD) model of the effect of denosumab on bone remodelling in PMO. To address the above clinical relevant questions, we design a wide range of current and virtual treatment regimens to study the effect of drug holiday duration and therapy resumption on the evolution of BTMs, BMD and mineral content. Our numerical simulation results indicate the symptomatic effect of denosumab, which is lost once treatment is stopped. This effect is most clearly seen on rapid loss of BMD to pre-treatment levels 12 months after the last injection (8% and 3.6% per year in the lumbar spine and femoral neck, respectively). Also, we identify that independently of the duration of drug holiday (i.e. 12, 16 or 18 months) resuming treatment can restore BMD quite effectively. However, the latter result does not consider the possibility of potential fractures that can occur during the drug holiday. Finally, we identify a treatment case most promising for achieving maintenance of BMD and mineral content, while moderately increasing BTMs. The latter case uses no drug holiday, but reduces the most commonly prescribed denosumab dose (60 mg every 6 months) by half at same interval.

Denosumab for cancer-related bone loss

INTRODUCTION

Prolonged use of anti-cancer treatments in breast and prostate tumors alters physiological bone turnover leading to adverse skeletal related events, such as osteoporosis, loss of bone mass, and increased risk of fractures. These complications known as cancer treatment-induced bone loss (CTIBL) should be managed with bone targeting agents such as the bisphosphonates and denosumab. The latter is a monoclonal antibody against the receptor activator of nuclear factor-kB ligand (RANKL) that suppresses osteoclasts function and survival increasing bone mass.

AREAS COVERED

This review will focus on the mechanisms associated with bone loss induced by cancer treatments and the most recent evidence about the use of denosumab as preventive and therapeutic strategy to protect bone health. Moreover, we will discuss several key aspects regarding the clinical practical use of denosumab to optimize the management of CTLIB in breast and prostate cancer.

EXPERT OPINION

Denosumab treatment strongly prevents cancer therapies-related skeletal issues in breast and prostate cancer with a good safety profile. Adjuvant six-monthly denosumab delays the time to first fracture onset in early stage breast cancer patients with normal or altered bone mineral density (BMD). Similarly, denosumab treatment is able to prevent fractures and BMD loss in nonmetastatic prostate cancer patients.

Repurposing denosumab in lung cancer beyond counteracting the skeletal related events: an intriguing perspective

INTRODUCTION

Repurposing denosumab in lung cancer therapeutics capitalizes on its well-established role in preventing the skeletal related events (SREs) and its emerging, yet elusive, bone-independent role, assigned to inhibit the contribution of RANKL to cancer initiation and progression.

AREAS COVERED

The present review presents the available preclinical and clinical data indicating that denosumab may provide survival benefit to lung cancer patients beyond the counteraction of SREs.

EXPERT OPINION

Despite the preliminary data heralding the potential of denosumab to increase overall survival in lung cancer, the embracement of this strategy in clinical practice cannot be advocated until large randomized clinical trials consolidate its safety and efficacy. Given the improvement of lung cancer prognosis ascribed to revolutionary targeted treatment agents, the possibility of denosumab-related increased risk of second primary malignancies merits further evaluation. Many challenges in endorsing denosumab as a strategy to treat lung cancer beyond SREs prevention are pending counteraction, including: (i) patient selection guided by validated predictive and prognostic biomarkers; (ii) assessment of long-term outcomes; (iii) evaluation of benefit-risk ratio; (iv) translational research; (v) combination of denosumab with other targeted therapies; (vi) integration of genomic biomarkers, immune-related biomarkers, and biomarkers of active RANKL pathway to guide the decision-making process.

Favorable skeletal benefit/risk of long-term denosumab therapy: A virtual-twin analysis of fractures prevented relative to skeletal safety events observed

Antiresorptive therapies reduce fracture risk; however, long-term bone turnover inhibition may raise concerns about rare, but serious, skeletal adverse events-atypical femoral fracture (AFF) and osteonecrosis of the jaw (ONJ). Denosumab, a fully human monoclonal antibody against RANKL, has demonstrated sustained low vertebral and nonvertebral fracture rates with low skeletal adverse event rates in the 3-year FREEDOM trial and its 7-year Extension (in which all subjects received open-label denosumab). In this analysis, we aimed to estimate fractures prevented relative to skeletal adverse events observed with 10 years of denosumab therapy. We modeled a hypothetical placebo group using the virtual-twin method, thereby allowing calculation of fractures prevented with denosumab treatment (relative to the virtual-placebo group) in the context of AFF or ONJ events observed in the long-term denosumab group. Estimated virtual-placebo and observed long-term denosumab exposure-adjusted fracture rates per 100,000 subject-years were calculated for fractures classified as clinical (3180 and 1777, respectively), major osteoporotic (2699 and 1525), vertebral (1879 and 901), and nonvertebral (2924 and 1528), and compared with observed AFF and ONJ in the long-term denosumab group (5 and 35 per 100,000 subject-years, respectively). The skeletal benefit/risk ratio (fractures prevented per adverse event observed) for clinical fractures was 281 (AFF) and 40 (ONJ). Based on this model, denosumab treatment for up to 10 years has a favorable skeletal benefit/risk profile when comparing fractures prevented per skeletal adverse event observed. Clinical trial registration: NCT00089791, NCT00523341.

Second rebound-associated vertebral fractures after denosumab discontinuation

Here, we report the case of a 69-year-old female who discontinued denosumab to undergo dental treatment. She subsequently suffered rebound-associated vertebral fractures (RVFs) twice. Denosumab is approved in several countries for osteoporosis treatment. Its discontinuation can result in bone turnover rebound increase and rapid bone mineral density loss. Rebound-associated vertebral fractures (RVFs) after discontinuing denosumab have been widely reported. We previously reported the case of a patient who suffered RVFs after discontinuing denosumab to undergo dental treatment. A 69-year-old female suffered five acute VFs 10 months after the last denosumab injection. The current report identifies the risks associated with denosumab discontinuation to undergo dental treatment. The patient described in this report also underwent an additional clinical course after the first RVFs. Next month after the first RVFs, she developed severe back pain when she changed her posture. Magnetic resonance imaging showed new RVFs at T9 and T12 levels. This case indicates that RVFs may occur more than once. In addition, it suggests that additional denosumab injections do not completely eliminate the risk of RVFs.

Elevated Bone Hardness Under Denosumab Treatment, With Persisting Lower Osteocyte Viability During Discontinuation

Denosumab is a potent osteoclast inhibitor targeted to prevent osteoporotic bone loss and thereby reduce fractures in the aging population. Recently, an elevated risk of rebound fractures following denosumab discontinuation was identified, unless patients were transitioned to an alternative antiresorptive medication. How denosumab affects the interaction of mechanosensitive osteocytes and bone quality remains unknown. We hypothesized that denosumab influences osteocyte function contributing to bone reorganization and increased fractures during discontinuation. Bone quality and osteocytes were assessed in archived iliac crest bone biopsies obtained from patients with high fracture occurrence from 2011 to 2016. Biopsies were obtained due to high fracture occurrence prior and during osteoporosis therapy from (i) patients with at least two semiannual subcutaneous injections of 60 mg denosumab, (ii) patients with rebound fractures during discontinuation, and (iii) patients of a treatment-naive group. In total, biopsies from 43 individuals were analyzed (mean age, 65.5 ± 12.1 years). Our results showed that during denosumab treatment, iliac cortical bone had a higher bone tissue hardness compared to treatment-naive bone (p = 0.0077) and a higher percentage of mineralized osteocyte lacunae (p = 0.0095). The density of empty osteocyte lacunae was higher with denosumab compared to treatment-naive (p = 0.014) and remained high in trabecular bone during discontinuation (p = 0.0071). We conclude that during denosumab treatment, increased bone hardness may contribute to improved fracture resistance. In biopsies from patients with high fracture occurrence, denosumab treatment reduced osteocyte viability, an effect that persisted during treatment discontinuation. High-resolution imaging of osteocyte viability indicates a role for osteocytes as a potential future mechanistic target to understand rebound bone loss and increased fractures with denosumab discontinuation.

Fracture incidence after denosumab discontinuation: Real-world data from a large healthcare provider

BACKGROUND

Vertebral fractures (VF) upon Denosumab (DMAB) discontinuation were first described as a distinct phenomenon in 2015, yet the magnitude of this event remains undetermined.

OBJECTIVES

To estimate fracture risk after DMAB discontinuation, in a real-world setting.

METHODS

The computerized database of a 2.3-million members' state-mandated health organization was utilized to detect osteoporotic patients with at least two DMAB dispenses. Treatment discontinuation was defined as a refill gap of 3 months or more, while the discontinuation date was defined as an anticipated missed purchase date. Fractures were identified by an osteoporosis registry and individually adjudicated by an expert's review. Fractures occurring within one year from discontinuation among DMAB discontinuers (DD) and from the 2nd year of treatment onwards for persistent users (PU) were included.

RESULTS

A total of 1500 DD (92% females, mean ± SD age = 71.8 ± 9.5y), and 1610 PU (91%, 71.7 ± 8.8) were identified. At baseline, the groups were comparable in fracture- history, bisphosphonate exposure, smoking, and bone density. Multiple VF occurred in 12 (0.8%) DD vs. 2 (0.1%) PU (p = 0.006). The overall rate of fractures per 100 patient-years of follow-up was significantly higher in DD than PU (RR 3.2, 95% CI 2.2-4.8), as well as the rate of VF (RR 4.7, 95% CI 2.3-9.6) and multiple VF (RR 14.6, 95% CI 3.3-65.3, effect size 1.06).

CONCLUSIONS

Patients who discontinue DMAB are at greater risk of major OP fractures than those who persist with treatment. Same is true for clinical multiple vertebral fractures, yet the incidence of the latter was low. These findings demonstrate a need for greater awareness and thoughtful management of DMAB discontinuation.

Denosumab utilization among older adults in Ontario: patient characteristics, persistence with therapy, and return to therapy after an extended gap

We studied 46,797 older adults who initiated denosumab in Ontario, Canada. Patient characteristics remained relatively stable over time and aligned with public reimbursement restrictions. Almost half of patients persisted with therapy for at least 3 years. Fifty-nine percent of patients who discontinued denosumab returned to treatment within 3.6 years.

INTRODUCTION

The purpose of this study was to describe the characteristics of patients who initiated denosumab and estimate persistence with therapy.

METHODS

We identified older adults (aged ≥ 66 years) in Ontario who initiated denosumab between 2012/02 and 2015/03 and followed them to 2016/03. Patient characteristics were summarized using medical and pharmacy claims in the year before starting denosumab and osteoporosis drug use considered since 1996/10. Persistence with denosumab and return after discontinuation (> 90-day gap) were estimated using Kaplan-Meier curves. Analyses were stratified by community and long-term care (LTC) residence.

RESULTS

We identified 46,797 patients (monthly mean = 1263, SD = 187); 97% female, 13% LTC. Community-dwelling patients had a higher prevalence of bone mineral density testing (62% vs. 5%), yet were younger (mean age 78.5 vs. 86.6 years) and had lower prevalence of hip fractures (3% vs. 10%) compared to LTC patients. Eighty-two percent of patients had used osteoporosis medications in the past; 99% of whom took an oral bisphosphonate. Persistence was similar between community-dwelling and LTC patients: 59% persisted ≥ 2 years, 48% ≥ 3 years, and 38% ≥ 4 years, yet a larger proportion of LTC patients returned to denosumab after discontinuation (76% vs. 57%).

CONCLUSIONS

Denosumab utilization is increasing at a steady rate in Ontario. However, persistence remains a concern given the highly reversible pharmacokinetic profile of denosumab that results in a rapid increased fracture risk following discontinuation. Over 80% of patients had a history of oral bisphosphonate therapy, which may persist in bone despite discontinuing denosumab. Consequently, better understanding of denosumab safety and effectiveness among real-world users is important.

Long-term persistence in patients with osteoporosis receiving denosumab in routine practice: 36-month non-interventional, observational study

Persistence rates over 36 months with denosumab in patients diagnosed with osteoporosis in a real-world setting were examined, along with baseline patient characteristics predictive of persistence. This study represents the longest observational period with denosumab persistence and shows higher persistence rates when compared to bisphosphonates.

INTRODUCTION

The study objective was to describe long-term persistence with denosumab among patients treated for osteoporosis in a real-world setting. We also sought to examine patient characteristics predictive of persistence. Lastly, this study attempted to place the results in context by conducting a literature review of published persistence data for denosumab.

METHODS

This retrospective, non-interventional study analyzed 1158 patients from a specialty community private practice to assess patient persistence with denosumab in routine care. Persistence was defined as receiving seven denosumab injections, using an 8-week permissible gap, over 36 months. Non-persistent patients were further investigated retrospectively to identify reasons for discontinuation, when available.

RESULTS

Demographic analysis showed a population of 1158 patients with mean age 68.4 years old and baseline T-score - 2.7; nearly half of which experienced a prior osteoporosis-related fracture. In a Kaplan-Meier survival analysis, 36-month persistence overall was 50.7%. Net persistence, as defined by receiving seven injections in the allowable time frame, was 64.2% of the cohort. In a multivariate analysis, prior vertebral fractures and recent osteoporosis therapy were associated with higher persistence; age greater than 75 years was associated with non-persistence. Reasons for discontinuation were available in 91.6% of non-persistent patients and categorized to include the ten most common explanations.

CONCLUSION

This study to our knowledge represents the longest continuous observational period providing data on denosumab persistence in a real-world setting. The total persistence noted is quite robust when compared to bisphosphonates and is within the upper range of prior published studies of denosumab with shorter observation periods.

Changes in Dkk-1, sclerostin, and RANKL serum levels following discontinuation of long-term denosumab treatment in postmenopausal women

PURPOSE

The positive effects of denosumab (DMAb) on bone mineral density (BMD) are quickly reversible after its discontinuation. We investigated whether this rebound was associated with dysregulation of the Wnt canonical pathway and/or by the increase in the receptor-activator of nuclear factor-kappa B ligand (RANKL) serum levels.

METHODS

The study included patients (n = 15) with postmenopausal osteoporosis to whom DMAb was administered for 78 months and then discontinued. We collected BMD data at baseline/month 0 (M0), M60, M84 (6 months after last DMAb administration, coinciding when the next DMAb dose would typically be due), and after 3 and 12 months of follow-up (FU-M3 and FU-M12, respectively). Serum C-terminal telopeptide of type 1 collagen (CTX-I), Dickkopf-1 (Dkk-1), and sclerostin were measured at M0, M60, M84, FU-M3, and FU-M12. Serum N-terminal propeptide of type 1 procollagen (PINP) and RANKL were dosed at M60, M84, FU-M3, and FU-12.

RESULTS

We found a significant decrease in the T-score at all sites at FU-M12, when compared to M84 (-0.51 ± 0.91 at the lumbar spine; -0.72 ± 0.33 at the total hip; and -0.42 ± 0.27 at the femoral neck, p < 0.05). After DMAb discontinuation (M84 vs FU M12) CTX-I, PINP increased already at FU-M3 (+0.921 ± 0.482 ng/mL, +126.60 ± 30.36 ng/mL, respectively, p < 0.01), RANKL increased at FU-M12 (+0.041 ± 0.062 ng/mL, p < 0.05), while Dkk-1 and sclerostin decreased at FU-M12 (-10.90 ± 11.80 and - 13.00 ± 10.52 pmol/L, respectively, p < 0.01). No changes in BMD or any of the markers were found between M60 and M84.

CONCLUSIONS

RANKL serum levels progressively increased after discontinuation of long-term DMAb while Dkk-1 and sclerostin serum levels decreased. The increase in RANKL serum levels supports the hypothesis of a sudden loss of inhibition of the resting osteoclast line after DMAb clearance, with a hyperactivation of these cells. Our results suggest that the changes in serum Wnt inhibitors after DMAb suspension might represent a mere feedback response to the increased bone turnover.

Long-term treatment strategies for postmenopausal osteoporosis

PURPOSE OF REVIEW

Osteoporosis guidelines do not usually provide specific recommendations regarding what medication is most appropriate for individual patients. Generic oral bisphosphonates are often considered first-line treatment for osteoporosis, but treatment duration is limited, based on potential long-term safety concerns, and there is no consensus about what to do after 5 years. There are no recommendations concerning long-term management of osteoporosis over 30 or more years of postmenopausal life.

RECENT FINDINGS

This review attempts to specify medication choices and provide the best clinical management strategies for women at different stages of life and with different underlying disease severity. Because there is no evidence that considers the entire postmenopausal lifespan, much of the discussion here will be based on expert opinion. The review considers a role for estrogens and selective estrogen receptor modulators, oral and intravenous bisphosphonates, denosumab and the anabolic agents, teriparatide and abaloparatide.

SUMMARY

Optimal sequential monotherapy, over an average of 30 postmenopausal years, should be able to minimize exposure to pharmacology while maximizing benefits on bone strength and minimizing imminent and long-term risk of fracture.

Spontaneous vertebral fractures after denosumab discontinuation: A case collection and review of the literature

OBJECTIVE

Denosumab is an antiresorptive drug with demonstrated efficacy in the treatment of osteoporosis. However, discontinuation of this agent is associated with increased bone turnover and rapid bone loss, and more recently, with the development of vertebral fractures (VF) in some patients. Therefore, the aim of the study was to analyze the clinical characteristics, bone metabolism parameters and evolution of a group of patients who developed vertebral fractures after denosumab discontinuation. In addition, we reviewed the literature on this subject.

METHODS

During a period of 28 months (September 2015-January 2018) 7 women presenting spontaneous vertebral fractures after denosumab discontinuation were attended in the Rheumatology Department of our centre. We analyzed their clinical characteristics, bone metabolism parameters and evolution and reviewed the literature related to this subject.

RESULTS

The patients had received denosumab during 24-58 months (median 38), and developed a median of 5 VF per patient at 8-20 months (median 10) since the last dose of denosumab. Only 2 patients presented previous VF, and most (5 patients) received previous bisphosphonate treatment. After VF all restarted antiosteoporotic treatment with no further fractures during follow-up (median 19 months).

CONCLUSIONS

In this short series, previous bisphosphonate treatment does not seem to be a protective factor for the development of VF. The possible development of VF following discontinuation of denosumab must be taken into account in the clinical practice of physicians and dentists. Nonetheless, further studies are needed to improve the identification of patients at risk and the most adequate sequential treatment options.

Tumor Cell Dormancy and Reactivation in Bone: Skeletal Biology and Therapeutic Opportunities

In the advanced stages of many cancers, tumor cells disseminate from the primary site and colonize distant locations such as the skeleton. These disseminated tumor cells colonizing bone can evade treatments and survive for prolonged periods in a dormant state before becoming reactivated to form overt metastases. The precise interactions between tumor cells and the bone microenvironment that promote survival, dormancy, and reactivation are currently unknown; as a result, bone metastases remain incurable. In this review we discuss the unique cellular and microenvironmental features of endosteal bone that tumor cells engage with to persist and survive, and ultimately reactivate and proliferate. Specifically, we provide a detailed summary of current perspectives on the processes of tumor cell colonization of the skeleton, and the endosteal bone cells as critical controllers of the dormant cancer cell phenotype, as well as relevant microenvironmental effects such as hypoxia. Evidence for the role of the osteoclast in controlling dormant cancer cell reactivation in bone is highlighted, preceding a discussion of therapeutics targeting the bone microenvironment, including anti‐RANK ligand and bisphosphonate therapies and their potential utility in preventing tumor cell reactivation in addition to protecting bone from tumor‐induced destruction. © 2018 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

New and emerging concepts in the use of denosumab for the treatment of osteoporosis

Denosumab is a fully human monoclonal antibody to receptor activator of nuclear factor kappa-B ligand (RANKL), a cytokine expressed by cells of the osteoblast lineage that is a key regulator of osteoclastic bone resorption. By binding and neutralizing RANKL, denosumab inhibits osteoclast differentiation, activity, and survival. Clinical trials in postmenopausal women with osteoporosis have shown that it reduces the risk of vertebral fractures, nonvertebral fractures, and hip fractures, with a generally favorable safety profile. With a dose of 60 mg subcutaneously every 6 months, it is approved for: treatment of postmenopausal women and men with osteoporosis, and for women and men with glucocorticoid-induced osteoporosis who are at high risk for fracture; treatment to increase bone mass in men at high risk for fracture receiving androgen-deprivation therapy for nonmetastatic prostate cancer; and treatment to increase bone mass in women at high risk for fracture receiving adjuvant aromatase inhibitor therapy for breast cancer. Atypical femur fractures and osteonecrosis of the jaw have been reported in patients treated with denosumab. Discontinuation of denosumab is followed by rapidly rising bone turnover markers, decreasing bone density, and vertebral fracture risk that returns to baseline, with a possible increase in the risk of multiple vertebral fractures. Further study is needed to clarify this potential risk. After stopping long-term denosumab, patients should be switched to another antiresorptive agent to maintain the benefit achieved with denosumab.

Vertebral Fractures Following Denosumab Discontinuation in Patients with Prolonged Exposure to Bisphosphonates

Denosumab (DMAB) efficacy for treatment of osteoporosis was demonstrated in a pivotal trial with a reduction in vertebral and hip fractures during 3 years, and fracture risk reduction was sustained up to 10 years in an extension study. DMAB causes potent yet reversible inhibition of bone resorption. Bone density declines rapidly upon discontinuation and bone turnover markers increase above baseline in a rebound fashion. Spontaneous multiple vertebral fractures after DMAB discontinuation were recently reported. Prior treatment with bisphosphonates (BP) was postulated to decrease the risk for this alarming phenomenon. We aimed to describe our experience of fractures following DMAB withdrawal with special attention to past history of osteoporosis treatment. A phone survey of physicians engaged in bone metabolism from nine hospitals in Israel was performed. Clinical data of the patients presenting with vertebral fractures upon DMAB discontinuation were summarized and compared to the previously published cases. Nine elderly (74.2 ± 5.3 years) female patients were identified. Most patients had a prolonged prior exposure to BP (7.4 ± 3.2 years). All but one sustained osteoporotic fractures prior to DMAB initiation and their FRAX scores were high. Thirty-six vertebral fractures were identified in nine patients. Eight patients presented with multiple fractures, and most fractures were spontaneous. In line with the previous reports, the timing and severity of the fractures raise concern of DMAB discontinuation effect. Prolonged BP exposure in most of our patients challenges the protective effect hypothesis. Care providers, patients, and regulatory authorities should be aware of the possible risk of DMAB treatment interruption.

Review of the guideline of the American College of Physicians on the treatment of osteoporosis

This review, endorsed by the International Osteoporosis Foundation and the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases, summarizes several failings of the recent guidelines of the American College of Physicians (ACP) on the treatment of low bone density or osteoporosis to prevent fractures.

INTRODUCTION

The ACP recently issued guidelines for the treatment of low bone density or osteoporosis to prevent fractures.

METHODS

Literature review and critical review of the ACP guidelines.

RESULTS

The guideline is lacking in scope due to the endorsement of treatment based on T-scores rather than fracture risk assessment and in failure to adequately consider anabolic therapies.

CONCLUSIONS

The ACP guideline appears outdated.

Adrenal crisis after first infusion of zoledronic acid: a case report

Patients with Addison's disease are at greater risk of having reduced bone mineral density and hip fractures and are thus more likely to receive a bisphosphonate than their peers. Potent intravenous bisphosphonates could provoke an acute phase reaction. An 80-year-old female with Addison's disease received her first infusion of zoledronic acid for osteoporosis at our outpatient clinic around noon. Despite doubling her usual afternoon hydrocortisone dose, she became feverish, nauseous, extremely weak, and hypotensive over the night. When transported to the nearest general hospital the next morning, the patient was found to have signs of hypovolemic shock and she was admitted to the ICU. Crystalloid infusion, followed by dobutamine and norepinephrine drip, had no effect. Only after her European emergency card for glucocorticoid cover was found, adrenal crisis was recognized, and she was immediately given an intravenous bolus of hydrocortisone followed by continuous hydrocortisone infusion. The patient rapidly improved and was transferred to a regular ward the next day, where hydrocortisone dose was gradually tapered. Our experience might suggest that patients with Addison's disease should probably start their treatment with zoledronic acid in a hospital setting. Their usual oral dose of hydrocortisone should be doubled or even tripled. Careful monitoring of these patients seems to be warranted, and intravenous hydrocortisone should be given if any symptoms or signs of the imminent adrenal crisis are noted.