Structure-based design of selective, orally available salt-inducible kinase inhibitors that stimulate bone formation in mice.

Osteoporosis is a major public health problem. Currently, there are no orally available therapies that increase bone formation. Intermittent parathyroid hormone (PTH) stimulates bone formation through a signal transduction pathway that involves inhibition of salt-inducible kinase isoforms 2 and 3 (SIK2 and SIK3). Here, we further validate SIK2/SIK3 as osteoporosis drug targets by demonstrating that ubiquitous deletion of these genes in adult mice increases bone formation without extraskeletal toxicities. Previous efforts to target these kinases to stimulate bone formation have been limited by lack of pharmacologically acceptable, specific, orally available SIK2/SIK3 inhibitors. Here, we used structure-based drug design followed by iterative medicinal chemistry to identify SK-124 as a lead compound that potently inhibits SIK2 and SIK3. SK-124 inhibits SIK2 and SIK3 with single-digit nanomolar potency in vitro and in cell-based target engagement assays and shows acceptable kinome selectivity and oral bioavailability. SK-124 reduces SIK2/SIK3 substrate phosphorylation levels in human and mouse cultured bone cells and regulates gene expression patterns in a PTH-like manner. Once-daily oral SK-124 treatment for 3 wk in mice led to PTH-like effects on mineral metabolism including increased blood levels of calcium and 1,25-vitamin D and suppressed endogenous PTH levels. Furthermore, SK-124 treatment increased bone formation by osteoblasts and boosted trabecular bone mass without evidence of short-term toxicity. Taken together, these findings demonstrate PTH-like effects in bone and mineral metabolism upon in vivo treatment with orally available SIK2/SIK3 inhibitor SK-124.

Recommendations for the conduct of clinical trials for drugs to treat or prevent sarcopenia.

PURPOSE: Sarcopenia is an age-related muscle condition which is frequently a precursor of frailty, mobility disability and premature death. It has a high prevalence in older populations and presents a considerable social and economic burden. Potential treatments are under development but, as yet, no guidelines support regulatory studies for new drugs to manage sarcopenia. The objective of this position paper is therefore to suggest a set of potential endpoints and target population definitions to stimulate debate and progress within the medico-scientific and regulatory communities. METHODS: A multidisciplinary expert working group was hosted by the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis, which reviewed and discussed the recent literature from a perspective of clinical experience and guideline development. Relevant parallels were drawn from the development of definition of osteoporosis as a disease and clinical assessment of pharmaceutical treatments for that indication. RESULTS: A case-finding decision tree is briefly reviewed with a discussion of recent prevalence estimations of different relevant threshold values. The selection criteria for patients in regulatory studies are discussed according to the aims of the investigation (sarcopenia prevention or treatment) and the stage of project development. The possible endpoints of such studies are reviewed and a plea is made for the establishment of a core outcome set to be used in all clinical trials of sarcopenia. CONCLUSIONS: The current lack of guidelines for the assessment of new therapeutic treatments for sarcopenia could potentially hinder the delivery of effective medicines to patients at risk.

Does Teriparatide Improve Femoral Neck Fracture Healing: Results From A Randomized Placebo-controlled Trial.

BACKGROUND: There is a medical need for therapies that improve hip fracture healing. Teriparatide (Forteo(®)/ Forsteo(®), recombinant human parathyroid hormone) is a bone anabolic drug that is approved for treatment of osteoporosis and glucocorticoid-induced osteoporosis in men and postmenopausal women at high fracture risk. Preclinical and preliminary clinical data also suggest that teriparatide may enhance bone healing. QUESTIONS/PURPOSES: We wished to test the hypotheses that treatment with teriparatide versus placebo would improve femoral neck fracture healing after internal fixation as measured by (1) frequency of revision surgery, (2) radiographic fracture healing, and (3) other outcomes including pain control, gait speed, and safety. METHODS: We initiated two separate, but identically designed, clinical trials to meet FDA requirements to provide substantial evidence to support approval of a new indication. The two prospective, randomized double-blind, placebo-controlled Phase III studies were designed to evaluate the effect of subcutaneous teriparatide (20 µg/day) for 6 months versus placebo on fracture healing at 24 months. The trials were conducted concurrently with a planned enrollment of 1220 patients per trial. However, enrollment was stopped owing to very slow patient accrual, and an a priori decision was made to pool the results of those studies for statistical analyses before study completion; pooling was specified in both protocols. Randomization was stratified by fixation (sliding hip screw or multiple cancellous screws) and fracture type (displaced or nondisplaced). An independent Central Adjudication Committee reviewed revision surgical procedures and radiographs. A total of 159 patients were randomized in the two trials (81 placebo, 78 teriparatide). The combined program had very low power to detect the originally expected treatment effect but had approximately 80% power to detect a larger difference of 12% between treatment groups for risk of revision surgery. RESULTS: The proportion of patients undergoing revision surgery at 12 months was 14% (11 of 81) in the placebo group versus 17% (13 of 78) in the teriparatide group. Central Adjudication Committee review excluded two of these patients treated with placebo from the primary analysis. After exclusions, the proportion of patients who did not undergo revision surgery at 12 months (primary endpoint) was not different between the study and placebo groups, at 88% in the placebo group (90% CI, 0.79-0.93) versus 84% in the teriparatide group (90% CI, 0.75-0.90; p = 0.743). There also were no differences between groups in the proportion of patients achieving radiographic fracture healing at 12 months (75% [61 of 81] placebo versus 73% [57 of 78] teriparatide; odds ratio, 0.89; 90% CI, 0.46-1.72; p = 0.692) or in measures of pain control (such as pain during ambulation, 92% [55 of 62] placebo versus 91% [52 of 57] teriparatide; odds ratio, 0.91; 90% CI, 0.25-3.37; p = 0.681). The frequency of patients reporting adverse events was 49% [40 of 81] in the placebo group versus 45% [35 of 78] in the teriparatide group (p = 0.634) during the 6-month treatment period. CONCLUSIONS: The small sample size limited this study's power to detect potential differences, and the results are exploratory. With the patients available, teriparatide did not decrease the risk of revision surgery, improve radiographic signs of fracture healing, or decrease pain compared with the placebo. The adverse event data observed were consistent with the teriparatide safety profile. Functional and health outcome data from the studies may help improve our understanding of patients recovering from femoral neck fractures. Further large controlled studies are required to determine the effect of teriparatide on fracture healing. LEVEL OF EVIDENCE: Level II, prospective study.

Selective oestrogen receptor modulators in prevention of breast cancer: an updated meta-analysis of individual participant data.

BACKGROUND: Tamoxifen and raloxifene reduce the risk of breast cancer in women at elevated risk of disease, but the duration of the effect is unknown. We assessed the effectiveness of selective oestrogen receptor modulators (SERMs) on breast cancer incidence. METHODS: We did a meta-analysis with individual participant data from nine prevention trials comparing four selective oestrogen receptor modulators (SERMs; tamoxifen, raloxifene, arzoxifene, and lasofoxifene) with placebo, or in one study with tamoxifen. Our primary endpoint was incidence of all breast cancer (including ductal carcinoma in situ) during a 10 year follow-up period. Analysis was by intention to treat. RESULTS: We analysed data for 83,399 women with 306,617 women-years of follow-up. Median follow-up was 65 months (IQR 54-93). Overall, we noted a 38% reduction (hazard ratio [HR] 0·62, 95% CI 0·56-0·69) in breast cancer incidence, and 42 women would need to be treated to prevent one breast cancer event in the first 10 years of follow-up. The reduction was larger in the first 5 years of follow-up than in years 5-10 (42%, HR 0·58, 0·51-0·66; p<0·0001 vs 25%, 0·75, 0·61-0·93; p=0·007), but we noted no heterogeneity between time periods. Thromboembolic events were significantly increased with all SERMs (odds ratio 1·73, 95% CI 1·47-2·05; p<0·0001). We recorded a significant reduction of 34% in vertebral fractures (0·66, 0·59-0·73), but only a small effect for non-vertebral fractures (0·93, 0·87-0·99). INTERPRETATION: For all SERMs, incidence of invasive oestrogen (ER)-positive breast cancer was reduced both during treatment and for at least 5 years after completion. Similar to other preventive interventions, careful consideration of risks and benefits is needed to identify women who are most likely to benefit from these drugs. FUNDING: Cancer Research UK.

Real-World Evidence to Support the Registration of a New Osteoporosis Medicinal Product in Europe.

Real-World Evidence (RWE), which has historically been used to support post-approval safety studies, has recently gained acceptance for new drug applications as supportive evidence or as new clinical evidence for medicinal products with orphan designation and/or in disease areas with high unmet need. Here, we present a case study for the use of RWE in the approval of abaloparatide in the European Union (EU) under the tradename Eladynos. In addition to data from the pivotal Phase 3 study, the marketing authorization application (MAA) included clinical data from additional interventional and observational studies, as well as post-marketing data obtained from the United States (US) market since approval of abaloparatide by the Food and Drug Administration (FDA) in 2017. The new interventional studies were not designed to assess fracture efficacy and cardiovascular safety which were topics of concern raised by the Committee for Medicinal Products for Human Use (CHMP) during their review of the initial MAA submitted in 2015. However, these studies taken together with the RWE formed the basis for a new MAA. Prior to the planned resubmission in the EU, national Scientific Advice (SA) was sought on the proposed clinical program, specifically on the relevance of Real-World Data (RWD) derived from an observational study to support and complement the efficacy and safety data already available from prospective randomized clinical trials. This case study demonstrates successful use of RWE to address a previously identified gap raised by the CHMP during the review of an earlier MAA, which led to the approval of Eladynos for the treatment of osteoporosis in the EU.

Response rates for lumbar spine, total hip, and femoral neck bone mineral density in men treated with abaloparatide: results from the ATOM study.

Osteoporosis in men is an underappreciated public health issue, accounting for approximately 30% of the societal burden of osteoporosis. Although the prevalence of osteoporosis in men is lower, fracture-related morbidity and mortality rates exceed those of women. Abaloparatide is a synthetic, 34-amino acid peptide with homology to human parathyroid hormone-related protein (PTHrP), which favors bone formation by selective activation of PTH receptor type 1. In the Abaloparatide for the Treatment of Men With Osteoporosis (ATOM; NCT03512262) trial, 228 men with primary or hypogonadism-associated osteoporosis were randomized to receive subcutaneous injections of abaloparatide 80 µg or placebo. Abaloparatide significantly improved LS, TH, and FN BMD when compared with placebo. In this prespecified analysis, the proportion of men with a percent change from baseline of >0%, >3%, and > 6% in BMD at the LS, TH, and FN at 3, 6, and 12 mo and/or a shift in T-score category (based on LS and TH T-scores) at 12 mo was compared between the abaloparatide and placebo groups in ATOM. There were significantly more men with a BMD gain of >3% at all 3 anatomical sites in the abaloparatide than placebo group at month 6 (18/122 [14.8%] vs 1/70 [1.4%], P = .002) and at month 12 (38/119 [31.9%] vs 1/66 [1.5%], P < .0001). At month 3, more men treated with abaloparatide than placebo had a > 3% BMD increase at the LS (82/134 [61.2%] vs 21/68 [30.9%], P < .0001). A greater proportion of men treated with abaloparatide had an improvement in T-score category from osteoporosis to low BMD or normal when compared with placebo. In conclusion, use of abaloparatide compared with placebo for 12 mo resulted in significant and rapid improvements in BMD in men with osteoporosis from the ATOM study.

Quality of life in sarcopenia and frailty.

The reduced muscle mass and impaired muscle performance that define sarcopenia in older individuals are associated with increased risk of physical limitation and a variety of chronic diseases. They may also contribute to clinical frailty. A gradual erosion of quality of life (QoL) has been evidenced in these individuals, although much of this research has been done using generic QoL instruments, particularly the SF-36, which may not be ideal in older populations with significant comorbidities. This review and report of an expert meeting presents the current definitions of these geriatric syndromes (sarcopenia and frailty). It then briefly summarizes QoL concepts and specificities in older populations and examines the relevant domains of QoL and what is known concerning QoL decline with these conditions. It calls for a clearer definition of the construct of disability, argues that a disease-specific QoL instrument for sarcopenia/frailty would be an asset for future research, and discusses whether there are available and validated components that could be used to this end and whether the psychometric properties of these instruments are sufficiently tested. It calls also for an approach using utility weighting to provide some cost estimates and suggests that a time trade-off study could be appropriate.

Effect of Abaloparatide on Bone Microarchitecture Assessed by Trabecular Bone Score in Women With Osteoporosis: Post Hoc Analysis of ACTIVE and ACTIVExtend.

Although bone mineral density (BMD) is a predictor of fracture, many fractures occur in women with T-scores > -2.5. Bone microarchitecture, assessed by trabecular bone score (TBS), predicts fracture risk independent of BMD. We evaluated whether abaloparatide improves TBS and whether TBS trends were associated with vertebral fracture risk reduction. Women with osteoporosis randomized to abaloparatide or placebo for 18 months (ACTIVE), followed by alendronate for 24 months (ACTIVExtend), with evaluable TBS, were included in this post hoc analysis (N = 911). TBS was calculated from spine BMD scans using an algorithm adjusted for tissue thickness (TBSth ) at baseline, 6, 18, and 43 months. Mean increments in TBSth from baseline within and between treatment groups, proportion of women with TBSth increments above least significant change (LSC) and proportion with degraded TBSth (<1.027) were calculated. Risk estimates for vertebral fracture were compared using binary logistic regressions adjusted for baseline age and spine BMD. At baseline, 42% had degraded TBSth . Mean TBSth increased 4% after 18 months abaloparatide (p < 0.001) and was unchanged with placebo. After 2 subsequent years of alendronate, the total cumulative TBSth increase was 4.4% with abaloparatide/alendronate and 1.7% with placebo/alendronate (group difference, p < 0.001). At 43 months, the proportion of women with degraded TBSth had declined to 21% with abaloparatide/alendronate and 37% with placebo/alendronate (p < 0.05). An increase in TBSth  ≥ LSC was observed in 50% of abaloparatide-treated women at 18 months and was associated with decreased odds (odds ratio [OR]; 95% confidence interval [CI]) of vertebral fracture (0.19; 95% CI, 0.04-0.80, 6 months; 0.30; 95% CI, 0.11-0.79, 43 months). In conclusion, abaloparatide increased TBSth rapidly and progressively over 18 months and increments were maintained over 2 years with alendronate. TBSth increase was associated with vertebral fracture risk reduction. Microarchitectural improvement may be one mechanism by which abaloparatide strengthens vertebral bone. © 2023 Radius Health, Inc and The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Efficacy and Safety of Transdermal Abaloparatide in Postmenopausal Women with Osteoporosis: A Randomized Study.

Anabolic therapies, recommended for patients at very high fracture risk, are administered subcutaneously (SC). The objective of this study was to evaluate the efficacy and safety of the abaloparatide microstructured transdermal system (abaloparatide-sMTS) as an alternative to the SC formulation. This phase 3, noninferiority study (NCT04064411) randomly assigned postmenopausal women with osteoporosis (N = 511) 1:1 to open-label abaloparatide administered daily via abaloparatide-sMTS or SC injection for 12 months. The primary comparison between treatment groups was the percentage change in lumbar spine bone mineral density (BMD) at 12 months, with a noninferiority margin of 2.0%. Secondary endpoints included percentage change in total hip and femoral neck BMD, bone turnover markers, dermatologic safety, and new clinical fracture incidence. At 12 months, percentage increase from baseline in lumbar spine BMD was 7.14% (SE: 0.46%) for abaloparatide-sMTS and 10.86% (SE: 0.48%) for abaloparatide-SC (treatment difference: -3.72% [95% confidence interval: -5.01%, -2.43%]). Percentage change in total hip BMD was 1.97% for abaloparatide-sMTS and 3.70% for abaloparatide-SC. Median changes from baseline at 12 months in serum procollagen type I N-terminal propeptide (s-PINP) were 52.6% for abaloparatide-sMTS and 74.5% for abaloparatide-SC. Administration site reactions were the most frequently reported adverse events (abaloparatide-sMTS, 94.4%; abaloparatide-SC, 70.5%). Incidence of serious adverse events was similar between groups. Mild or moderate skin reactions occurred with abaloparatide-sMTS with no identifiable risk factors for sensitization reactions. Few new clinical fractures occurred in either group. Noninferiority of abaloparatide-sMTS to abaloparatide-SC for percentage change in spine BMD at 12 months was not demonstrated; however, clinically meaningful increases from baseline in lumbar spine and total hip BMD were observed in both treatment groups. © 2023 Radius Health, Inc and The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

The Efficacy and Safety of Abaloparatide-SC in Men With Osteoporosis: A Randomized Clinical Trial.

Abaloparatide significantly increased bone mineral density (BMD) in women with postmenopausal osteoporosis and decreased risk of vertebral, nonvertebral, and clinical fractures compared with placebo. The Abaloparatide for the Treatment of Men with Osteoporosis (ATOM; NCT03512262) study evaluated the efficacy and safety of abaloparatide compared with placebo in men. Eligible men aged 40 to 85 years with osteoporosis were randomized 2:1 to daily subcutaneous injections of abaloparatide 80 µg or placebo for 12 months. The primary endpoint was change from baseline in lumbar spine BMD. Key secondary endpoints included BMD change from baseline at the total hip and femoral neck. A total of 228 men were randomized (abaloparatide, n = 149; placebo, n = 79). Baseline characteristics were similar across treatment groups (mean age, 68.3 years; mean lumbar spine BMD T-score, -2.1). At 12 months, BMD gains were greater with abaloparatide compared with placebo at the lumbar spine (least squares mean percentage change [standard error]: 8.48 [0.54] versus 1.17 [0.72]), total hip (2.14 [0.27] versus 0.01 [0.35]), and femoral neck (2.98 [0.34] versus 0.15 [0.45]) (all p < 0.0001). The most common (≥5%) treatment-emergent adverse events were injection site reaction, dizziness, nasopharyngitis, arthralgia, bronchitis, hypertension, and headache. During 12 months of abaloparatide treatment, men with osteoporosis exhibited rapid and significant improvements in BMD with a safety profile consistent with previous studies. These results suggest abaloparatide can be considered as an effective anabolic treatment option for men with osteoporosis. © 2022 Radius Health Inc and The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Validation of the Surrogate Threshold Effect for Change in Bone Mineral Density as a Surrogate Endpoint for Fracture Outcomes: The FNIH-ASBMR SABRE Project.

The surrogate threshold effect (STE) is defined as the minimum treatment effect on a surrogate that is reliably predictive of a treatment effect on the clinical outcome. It provides a framework for implementing a clinical trial with a surrogate endpoint. The aim of this study was to update our previous analysis by validating the STE for change in total hip (TH) BMD as a surrogate for fracture risk reduction; the novelty of this study was this validation. To do so, we used individual patient data from 61,415 participants in 16 RCTs that evaluated bisphosphonates (nine trials), selective estrogen receptor modulators (four trials), denosumab (one trial), odanacatib (one trial), and teriparatide (one trial) to estimate trial-specific treatment effects on TH BMD and all, vertebral, hip, and nonvertebral fractures. We then conducted a random effects meta-regression of the log relative fracture risk reduction against 24-month change in TH BMD, and computed the STE as the intersection of the upper 95% prediction limit of this regression with the line of no fracture reduction. We validated the STE by checking whether the number of fractures in each trial provided 80% power and determining what proportion of trials with BMD changes ≥ STE reported significant reductions in fracture risk. We applied this analysis to (i) the trials on which we estimated the STE; and (ii) trials on which we did not estimate the STE. We found that the STEs for all, vertebral, hip, and nonvertebral fractures were 1.83%, 1.42%, 3.18%, and 2.13%, respectively. Among trials used to estimate STE, 27 of 28 were adequately powered, showed BMD effects exceeding the STE, and showed significant reductions in fracture risk. Among the validation set of 11 trials, 10 met these criteria. Thus STE differs by fracture type and has been validated in trials not used to develop the approach. © 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).

Erratum for Abaloparatide in Postmenopausal Women With Osteoporosis and Type 2 Diabetes: A Post Hoc Analysis of the ACTIVE Study.

[This corrects the article DOI: 10.1002/jbm4.10346.].

Phase 1b Evaluation of Abaloparatide Solid Microstructured Transdermal System (Abaloparatide-sMTS) in Postmenopausal Women with Low Bone Mineral Density.

BACKGROUND AND OBJECTIVE: Abaloparatide, an anabolic osteoporosis treatment administered by subcutaneous (SC) injection, increases bone mineral density (BMD) and reduces fracture risk in postmenopausal women with osteoporosis. The abaloparatide-solid Microstructured Transdermal System [abaloparatide-sMTS (Kindeva, St Paul, MN, USA)], which delivers abaloparatide intradermally, is in development to provide an alternative method for abaloparatide delivery. The objective of this study was to evaluate the ability of subjects to self-administer abaloparatide-sMTS, based on pharmacokinetic and pharmacodynamic markers. METHODS: In this single-arm, open-label, Phase 1b study, 22 healthy postmenopausal women aged 50-85 years with low BMD were trained to self-administer abaloparatide-sMTS 300 µg once daily to the thigh for 5 min for 29 days. The primary endpoint was systemic exposure to abaloparatide. Secondary endpoints included percent change from baseline in serum procollagen type I N-terminal propeptide (s-PINP), patient experience, and safety. RESULTS: All 22 subjects completed the study. At baseline, mean age was 65.2 years, mean total hip T-score was - 1.32, and mean lumbar spine T-score was - 1.98. On Day 1, the median time to reach maximum concentration (Tmax) for abaloparatide-sMTS was 0.33 h and geometric mean (CV %) maximum concentration (Cmax) and area under the concentration-time curve from time 0 to the time of the last quantifiable concentration (AUC0-t) were 447 (38.0) pg/mL and 678 (45.3) pg·h/mL, respectively; the pharmacokinetic profile was similar on Days 15 and 29. Median percentage change in s-PINP was 45.4% and 64.4% at Days 15 and 29, respectively. The most common adverse events (AEs) were application site erythema, pain, and swelling, which were mostly of mild or moderate severity. No AEs led to study drug withdrawal and no serious AEs were reported. The success rate for self-administration at first application was 99.7%, and subject acceptability was high (~ 4.5 on a 5-point Likert Scale). CONCLUSIONS: Subjects successfully self-administered abaloparatide-sMTS, which provided a consistent pharmacokinetic profile over 29 days and produced s-PINP increases from baseline similar to that observed in the pivotal trial with abaloparatide-SC. Observed patient experience along with the clinical data support continued clinical development of abaloparatide-sMTS. TRIAL REGISTRATION NUMBER: NCT04366726, Date of registration 04/29/2020, retrospectively registered.

Osteoporosis is a serious health condition that causes more than 2 million fractures in the USA annually. Treatment options for osteoporosis include drugs that prevent bone resorption and anabolic agents that build new bone. Bone anabolic agents, such as abaloparatide, have been shown to increase bone mineral density and reduce the risk of fracture in postmenopausal women with osteoporosis. Currently, all bone anabolic agents are delivered by subcutaneous injection. However, some patients do not like injectable treatments, which can negatively impact patients' adherence to prescribed medication. In this study, we describe a novel mode of administration, the abaloparatide-solid Microstructured Transdermal System (abaloparatide-sMTS), which is applied to the thigh for 5 min and delivers abaloparatide intradermally. The study showed that this new method delivered abaloparatide into the blood as effectively as subcutaneous injections and demonstrated signs of activity in the body. Study participants were satisfied with abaloparatide-sMTS and found it easy to use. The most common side effects were skin related, including redness, pain, and swelling, which resolved shortly after dosing.

Early Effects of Abaloparatide on Bone Formation and Resorption Indices in Postmenopausal Women With Osteoporosis.

Anabolic osteoporosis drugs improve bone mineral density by increasing bone formation. The objective of this study was to evaluate the early effects of abaloparatide on indices of bone formation and to assess the effect of abaloparatide on modeling-based formation (MBF), remodeling-based formation (RBF), and overflow MBF (oMBF) in transiliac bone biopsies. In this open-label, single-arm study, 23 postmenopausal women with osteoporosis were treated with 80 µg abaloparatide daily. Subjects received double fluorochrome labels before treatment and before biopsy collection at 3 months. Change in dynamic histomorphometry indices in four bone envelopes were assessed. Median mineralizing surface per unit of bone surface (MS/BS) increased to 24.7%, 48.7%, 21.4%, and 16.3% of total surface after 3 months of abaloparatide treatment, representing 5.5-, 5.2-, 2.8-, and 12.9-fold changes, on cancellous, endocortical, intracortical, and periosteal surfaces (p < .001 versus baseline for all). Mineral apposition rate (MAR) was significantly increased only on intracortical surfaces. Bone formation rate (BFR/BS) was significantly increased on all four bone envelopes. Significant increases versus baseline were observed in MBF on cancellous, endocortical, and periosteal surfaces, for oMBF on cancellous and endocortical surfaces, and for RBF on cancellous, endocortical, and intracortical surfaces. Overall, modeling-based formation (MBF + oMBF) accounted for 37% and 23% of the increase in bone-forming surface on the endocortical and cancellous surfaces, respectively. Changes from baseline in serum biomarkers of bone turnover at either month 1 or month 3 were generally good surrogates for changes in histomorphometric endpoints. In conclusion, treatment with abaloparatide for 3 months stimulated bone formation on cancellous, endocortical, intracortical, and periosteal envelopes in transiliac bone biopsies obtained from postmenopausal women with osteoporosis. These increases reflected stimulation of both remodeling- and modeling-based bone formation, further elucidating the mechanisms by which abaloparatide improves bone mass and lowers fracture risk. © 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).

Treatment-Related Changes in Bone Turnover and Fracture Risk Reduction in Clinical Trials of Antiresorptive Drugs: Proportion of Treatment Effect Explained.

Few analyses of antiresorptive (AR) treatment trials relate short-term changes in bone turnover markers (BTMs) to subsequent fracture reduction seeking to estimate the proportion of treatment effect explained (PTE) by BTMs. Pooling such information would be useful to assess new ARs or novel dosing regimens. In the Foundation for the National Institutes of Health (FNIH) Bone Quality project, we analyzed individual-level data from up to 62,000 participants enrolled in 12 bisphosphonate (BP) and four selective estrogen receptor modulator (SERM) placebo-controlled fracture endpoint trials. Using BTM results for two bone formation markers (bone-specific alkaline phosphatase [bone ALP] and pro-collagen I N-propeptide [PINP]) and one bone resorption marker (C-terminal telopeptide of type I collagen [CTX]) and incident fracture outcome data, we estimated the PTE using two different models. Separate analyses were performed for incident morphometric vertebral, nonvertebral, and hip fractures over 1 to 5 years of follow-up. For vertebral fracture, the results showed that changes in all three BTMs at 6 months explained a large proportion of the treatment effect of ARs (57 to >100%), but not for and non-vertebral or hip fracture. We conclude that short-term AR treatment-related changes in bone ALP, PINP, and CTX account for a large proportion of the treatment effect for vertebral fracture. Change in BTMs is a useful surrogate marker to study the anti-fracture efficacy of new AR compounds or novel dosing regiments with approved AR drugs. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Effect of Abaloparatide vs Alendronate on Fracture Risk Reduction in Postmenopausal Women With Osteoporosis.

CONTEXT: The ACTIVE study demonstrated the antifracture efficacy of abaloparatide in postmenopausal women with osteoporosis. ACTIVExtend demonstrated sustained fracture risk reduction with alendronate in abaloparatide-treated participants from ACTIVE. A direct comparison of the efficacy of abaloparatide and antiresorptive therapies has not been performed. OBJECTIVE: The objective of this analysis is to compare the antifracture efficacy of abaloparatide in ACTIVE with that of alendronate in ACTIVExtend. DESIGN: In this post hoc analysis, the rate of new vertebral fractures for women in ACTIVExtend (N = 1139) was calculated based on baseline and endpoint radiographs for placebo or abaloparatide in ACTIVE and alendronate in ACTIVExtend. Vertebral fracture rates between abaloparatide and alendronate were compared in a Poisson regression model. Fracture rates for nonvertebral and clinical fractures were compared based on a Poisson model during 18 months of abaloparatide or placebo treatment in ACTIVE and 18 months of alendronate treatment in ACTIVExtend. RESULTS: The vertebral fracture rate was lower during abaloparatide treatment in ACTIVE (0.47 fractures/100 patient-years) than alendronate treatment in ACTIVExtend (1.66 fractures/100 patient-years) (relative risk reduction 71%; P = .027). Although the comparisons did not meet statistical significance, after switching from placebo (ACTIVE) to alendronate (ACTIVExtend), the rate of new vertebral fractures decreased from 2.49 to 1.66 fractures per 100 patient-years, and after switching from abaloparatide to alendronate from 0.47 to 0.19 fractures per 100 patient-years. The rates of nonvertebral fractures and clinical fractures were not significantly different. CONCLUSION: Initial treatment with abaloparatide may result in greater vertebral fracture reduction compared with alendronate in postmenopausal women with osteoporosis.

Abaloparatide: an anabolic treatment to reduce fracture risk in postmenopausal women with osteoporosis.

OBJECTIVE: Fractures due to osteoporosis represent a serious burden on patients and healthcare systems. The objective of this review is to provide an overview of the anabolic agent abaloparatide (ABL) for the treatment of postmenopausal women with osteoporosis at high risk for fracture. METHODS: A literature review was conducted using PubMed to identify articles focused on ABL published prior to February 10, 2020, using the search term "abaloparatide". RESULTS: ABL, a synthetic analog of human parathyroid hormone-related protein, increased bone mineral density (BMD), improved bone microarchitecture, and increased bone strength in preclinical and clinical studies. The pivotal phase 3 trial ACTIVE and its extension (ACTIVExtend) demonstrated the efficacy of initial treatment with ABL for 18 months followed by sequential treatment with alendronate (ALN) for an additional 24 months to reduce the risk of vertebral, nonvertebral, clinical, and major osteoporotic fractures and to increase BMD in postmenopausal women with osteoporosis. Discontinuations from ACTIVE were slightly more common in ABL-treated patients due to dizziness, palpitations, nausea, and headache. Post hoc analyses of ACTIVE and ACTIVExtend support the efficacy and safety of ABL in relevant subpopulations including postmenopausal women with various baseline risk factors, women ≥80 years, women with type 2 diabetes mellitus, and women with renal impairment. CONCLUSIONS: ABL is an effective and well-tolerated treatment for women with postmenopausal osteoporosis at high risk for fracture. Its therapeutic effects are sustained with subsequent ALN therapy.

Abaloparatide followed by alendronate in women ≥80 years with osteoporosis: post hoc analysis of ACTIVExtend.

OBJECTIVE: Fracture risk increases with age, but few studies focus on persons ≥80 years. In the ACTIVE trial, treatment with abaloparatide for 18 months reduced osteoporotic fracture risk and increased bone mineral density. These effects were maintained with 24 months alendronate treatment in ACTIVExtend. We postulated that similar improvements in bone mineral density and safety would be demonstrated in women ≥80 years. METHODS: Post hoc analyses of bone mineral density and fracture incidence in women with osteoporosis at high risk of fracture ≥80 years from ACTIVExtend. RESULTS: In total, 56 women aged ≥80 years at ACTIVE baseline entered the ACTIVExtend study; 46 of these completed the study. Mean age was 83.3 years; other baseline characteristics were similar. At the end of ACTIVE, bone mineral density increased at all sites for abaloparatide versus placebo. Bone mineral density increased in parallel in both groups during alendronate therapy (19 to 43 months) in ACTIVExtend. At month 43, mean percent change in bone mineral density from baseline was 17.2% abaloparatide/alendronate versus 8.6% placebo/alendronate (P < 0.0001) at the lumbar spine, 5.3% abaloparatide/alendronate versus 3.0% placebo/alendronate (P = 0.024) at the total hip, and 4.6% abaloparatide/alendronate versus 3.1% placebo/alendronate (P = 0.044) at the femoral neck. Fracture incidence was low and did not differ significantly between groups. Sequential treatment with abaloparatide followed by alendronate was well tolerated; the proportion of participants reporting adverse events was similar between groups. CONCLUSIONS: Sequential treatment with abaloparatide followed by alendronate (43 months follow-up) in this small subgroup of ACTIVExtend participants suggests abaloparatide is well tolerated and effective in women aged ≥80 years. : Video Summary:http://links.lww.com/MENO/A618.

Video Summary:http://links.lww.com/MENO/A618.

Cardiovascular Safety of Abaloparatide in Postmenopausal Women With Osteoporosis: Analysis From the ACTIVE Phase 3 Trial.

CONTEXT: Abaloparatide is a US Food and Drug Administration-approved parathyroid hormone-related peptide analog for treatment of osteoporosis in postmenopausal women at high risk of fracture. OBJECTIVES: We assessed the cardiovascular safety profile of abaloparatide. DESIGN: Review of heart rate (HR), blood pressure (BP), and cardiovascular-related adverse events (AEs), including major adverse cardiovascular events (MACEs) and heart failure (HF) from: (a) ACTIVE (NCT01343004), a phase 3 trial that randomized 2463 postmenopausal women with osteoporosis to abaloparatide, teriparatide, or placebo for 18 months; (b) ACTIVExtend (NCT01657162), where participants from the abaloparatide and placebo arms received alendronate for 2 years; and (c) a pharmacology study in 55 healthy adults. RESULTS: Abaloparatide and teriparatide transiently increased HR relative to placebo. Following first dose, mean (standard deviation [SD]) HR change from pretreatment to 1 hour posttreatment was 7.9 (8.5) beats per minute (bpm) for abaloparatide, 5.3 (7.5) for teriparatide, and 1.2 (7.1) for placebo. A similar pattern was observed over subsequent visits. In healthy volunteers, HR increase resolved within 4 hours. The corresponding change in mean supine systolic and diastolic BP 1 hour posttreatment was -2.7/-3.6 mmHg (abaloparatide), -2.0/-3.6 (teriparatide), and -1.5/-2.3 (placebo). The percentage of participants with serious cardiac AEs was similar among groups (0.9%-1.0%). In a post hoc analysis, time to first incidence of MACE + HF was longer with abaloparatide (P = 0.02 vs placebo) and teriparatide (P = 0.04 vs placebo). CONCLUSIONS: Abaloparatide was associated with transient increases in HR and small decreases in BP in postmenopausal women with osteoporosis, with no increase in risk of serious cardiac AEs, MACE, or HF.

Effects of abaloparatide and teriparatide on bone resorption and bone formation in female mice.

Intermittent administration of PTH type 1 receptor (PTH1R) agonists increases bone remodeling, with greater stimulation of bone formation relative to bone resorption causing net gains in bone mass. This pharmacodynamic feature underlies the bone-building effects of teriparatide and abaloparatide, the only PTH1R agonists approved to reduce osteoporotic fracture risk in postmenopausal women. This study in 8-week-old female mice compared bone resorption and formation responses to these agents delivered at the same 10 µg/kg dose, and a 40 µg/kg abaloparatide dose was also included to reflect its 4-fold higher approved clinical dose. Peptides or vehicle were administered by daily supra-calvarial subcutaneous injection for 12 days, and local (calvarial) and systemic (L5 vertebral and tibial) responses were evaluated by histomorphometry. Terminal bone histomorphometry data indicated that calvarial resorption cavities were similar in both abaloparatide groups versus vehicle controls, whereas the teriparatide group had more calvarial resorption cavities compared with the vehicle or abaloparatide 40 µg/kg groups. The bone resorption marker serum CTX was significantly lower in the abaloparatide 40 µg/kg group and similar in the other two active treatment groups compared with vehicle controls. Both peptides increased trabecular bone formation rate (BFR) in L5 and proximal tibia versus vehicle, and L5 BFR was higher with abaloparatide 40 µg/kg versus teriparatide. At the tibial diaphysis, periosteal BFR was higher with abaloparatide 40 µg/kg versus vehicle or teriparatide, and endocortical BFR was higher with teriparatide but not with abaloparatide 10 or 40 µg/kg versus vehicle. Few differences in structural or microarchitectural bone parameters were observed with this brief duration of treatment. In summary, calvarial bone resorption cavity counts were higher in the teriparatide group versus the vehicle and abaloparatide 40 µg/kg groups, and the abaloparatide 40 µg/kg group had lower serum CTX versus vehicle. L5 and tibial trabecular bone formation indices were higher in all three active treatment groups versus vehicle. The abaloparatide 40 µg/kg group had higher L5 trabecular BFR and tibial periosteal BFR versus teriparatide, whereas tibial endocortical BFR was higher with teriparatide but not abaloparatide. Together, these findings in female mice indicate that an improved balance of bone formation versus bone resorption is established shortly after initiating treatment with abaloparatide.