Remodeling- and Modeling-Based Bone Formation With Teriparatide Versus Denosumab: A Longitudinal Analysis From Baseline to 3 Months in the AVA Study.

There has been renewed interest of late in the role of modeling-based formation (MBF) during osteoporosis therapy. Here we describe early effects of an established anabolic (teriparatide) versus antiresorptive (denosumab) agent on remodeling-based formation (RBF), MBF, and overflow MBF (oMBF) in human transiliac bone biopsies. Postmenopausal women with osteoporosis received subcutaneous teriparatide (n = 33, 20 µg/d) or denosumab (n = 36, 60 mg once/6 months), open-label for 6 months at 7 US and Canadian sites. Subjects received double fluorochrome labeling at baseline and before biopsy at 3 months. Sites of bone formation were designated as MBF if the underlying cement line was smooth, RBF if scalloped, and oMBF if formed over smooth cement lines adjacent to scalloped reversal lines. At baseline, mean RBF/bone surface (BS), MBF/BS, and oMBF/BS were similar between the teriparatide and denosumab groups in each bone envelope assessed (cancellous, endocortical, periosteal). All types of formation significantly increased from baseline in the cancellous and endocortical envelopes (differences p < 0.001) with teriparatide (range of changes 2.9- to 21.9-fold), as did MBF in the periosteum (p < 0.001). In contrast, all types of formation were decreased or not significantly changed with denosumab, except MBF/BS in the cancellous envelope, which increased 2.5-fold (difference p = 0.048). These data highlight mechanistic differences between these agents: all 3 types of bone formation increased significantly with teriparatide, whereas formation was predominantly decreased or not significantly changed with denosumab, except for a slight increase in MBF/BS in the cancellous envelope. © 2017 American Society for Bone and Mineral Research.

Longitudinal Effects of Teriparatide or Zoledronic Acid on Bone Modeling- and Remodeling-Based Formation in the SHOTZ Study.

Previously, we reported on bone histomorphometry, biochemical markers, and bone mineral density distribution after 6 and 24 months of treatment with teriparatide (TPTD) or zoledronic acid (ZOL) in the SHOTZ study. The study included a 12-month primary study period, with treatment (TPTD 20 µg/d by subcutaneous injection or ZOL 5 mg/yr by intravenous infusion) randomized and double-blind until the month 6 biopsy (TPTD, n = 28; ZOL, n = 30 evaluable), then open-label, with an optional 12-month extension receiving the original treatment. A second biopsy (TPTD, n = 10; ZOL, n = 9) was collected from the contralateral side at month 24. Here we present data on remodeling-based bone formation (RBF), modeling-based bone formation (MBF), and overflow modeling-based bone formation (oMBF, modeling overflow adjacent to RBF sites) in the cancellous, endocortical, and periosteal envelopes. RBF was significantly greater after TPTD versus ZOL in all envelopes at 6 and 24 months, except the periosteal envelope at 24 months. MBF was significantly greater with TPTD in all envelopes at 6 months but not at 24 months. oMBF was significantly greater at 6 months in the cancellous and endocortical envelopes with TPTD, with no significant differences at 24 months. At 6 months, total bone formation surface was also significantly greater in each envelope with TPTD treatment (all p < 0.001). For within-group comparisons from 6 to 24 months, no statistically significant changes were observed in RBF, MBF, or oMBF in any envelope for either the TPTD or ZOL treatment groups. Overall, TPTD treatment was associated with greater bone formation than ZOL. Taken together the data support the view that ZOL is a traditional antiremodeling agent, wheareas TPTD is a proremodeling anabolic agent that increases bone formation, especially that associated with bone remodeling, including related overflow modeling, with substantial modeling-based bone formation early in the course of treatment. © 2017 American Society for Bone and Mineral Research.

Differential Effects of Teriparatide and Zoledronic Acid on Bone Mineralization Density Distribution at 6 and 24 Months in the SHOTZ Study.

The Skeletal Histomorphometry in Patients on Teriparatide or Zoledronic Acid Therapy (SHOTZ) study assessed the progressive effects of teriparatide (TPTD) and zoledronic acid (ZOL) on bone remodeling and material properties in postmenopausal women with osteoporosis. Previously, we reported that biochemical and histomorphometric bone formation indices were significantly higher in patients receiving TPTD versus ZOL. Here we report bone mineralization density distribution (BMDD) results based on quantitative backscattered electron imaging (qBEI). The 12-month primary study was randomized and double blind until the month 6 biopsy, then open label. Patients (TPTD, n = 28; ZOL, n = 31) were then eligible to enter a 12-month open-label extension with their original treatment: TPTD 20 µg/d (subcutaneous injection) or ZOL 5 mg/yr (intravenous infusion). A second biopsy was collected from the contralateral side at month 24 (TPTD, n = 10; ZOL, n = 10). In cancellous bone, ZOL treatment was associated at 6 and 24 months with significantly higher average degree of mineralization (CaMEAN, +2.2%, p = 0.018; +3.9%, p = 0.009, respectively) and with lower percentage of low mineralized areas (CaLOW , -34.6%, p = 0.029; -33.7%, p = 0.025, respectively) and heterogeneity of mineralization CaWIDTH (-12.3%, p = 0.003; -9.9%, p = 0.012, respectively), indicating higher mineralization density and more homogeneous mineral content versus TPTD. Within the ZOL group, significant changes were found in all parameters from month 6 to 24, indicating a progressive increase in mineralization density. In sharp contrast, mineralization density did not increase over time with TPTD, reflecting ongoing deposition of new bone. Similar results were observed in cortical bone. In this study, TPTD stimulated new bone formation, producing a mineralized bone matrix that remained relatively heterogeneous with a stable mean mineral content. ZOL slowed bone turnover and prolonged secondary mineralization, producing a progressively more homogeneous and highly mineralized bone matrix. Although both TPTD and ZOL increase clinical measures of bone mineral density (BMD), this study shows that the underlying mechanisms of the BMD increases are fundamentally different. © 2016 American Society for Bone and Mineral Research.

A Longitudinal Study of Skeletal Histomorphometry at 6 and 24 Months Across Four Bone Envelopes in Postmenopausal Women With Osteoporosis Receiving Teriparatide or Zoledronic Acid in the SHOTZ Trial.

Previously, we reported the effects of teriparatide (TPTD) and zoledronic acid (ZOL) on bone formation based on biochemical markers and bone histomorphometry of the cancellous envelope at month 6 in postmenopausal women with osteoporosis who participated in the 12-month primary Skeletal Histomorphometry in Subjects on Teriparatide or Zoledronic Acid Therapy (SHOTZ) study. Patients were eligible to enter a 12-month extension on their original treatment regimen: TPTD 20 µg/day (s.c. injection) or ZOL 5 mg/year (i.v. infusion). A second biopsy was performed at month 24. Here we report longitudinal changes between and within each treatment group in the cancellous, endocortical, intracortical, and periosteal bone envelopes in patients with evaluable biopsies at months 6 and 24 (paired data set: TPTD, n = 10; ZOL, n = 9). Between-group differences are also reported in the larger set of patients with evaluable biopsies at month 6 (TPTD, n = 28; ZOL, n = 30). Data from the cancellous envelope at month 6 or month 24 provided a reference to compare differences across envelopes within each treatment group. The 24-month results extend our earlier report that TPTD and ZOL possess different tissue-level mechanisms of action. Moreover, these differences persisted for at least 2 years in all four bone envelopes. Few longitudinal differences were observed within or across bone envelopes in ZOL-treated patients, suggesting that the low bone formation indices at month 6 persisted to month 24. Conversely, the magnitude of the effect of TPTD on bone formation varied across individual envelopes: median values for mineralizing surface (MS/BS) and bone formation rate (BFR/BS) at month 6 were approximately 3-fold to 5-fold higher in the endocortical and intracortical envelopes compared to the cancellous envelope. Although MS/BS and BFR/BS declined in these envelopes at month 24, median values continued to exceed, or were not significantly different from, those in the cancellous envelope. This study demonstrates for the first time that bone formation indices are higher with TPTD treatment than with ZOL in all four bone envelopes and the difference persists for at least 2 years. Moreover, the magnitude of the effect of TPTD in cortical bone remains robust at 24 months. © 2016 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research (ASBMR).

Differential Effects of Teriparatide and Denosumab on Intact PTH and Bone Formation Indices: AVA Osteoporosis Study.

We compared effects of teriparatide and denosumab on PTH, bone turnover markers, and bone histomorphometry in osteoporotic postmenopausal women. The findings were inconsistent with an early indirect anabolic effect of denosumab.

Characteristics of Latinas in Puerto Rico and the US mainland receiving teriparatide in the DANCE observational study.

OBJECTIVE: The Direct Assessment of Nonvertebral Fractures in Community Experience (DANCE) study investigated the use of teriparatide in men and women with osteoporosis in the United States (US) and Puerto Rico (PR). In a sub-analysis, we evaluated whether the baseline characteristics of Latinas differed from those of white women in the study population and whether any patient attributes affected physicians' decisions to prescribe teriparatide. METHODS: We assessed 3 patient cohorts treated with teriparatide 20 microg once daily for up to 24 months: 1) PR Latinas, 2) US Latinas, and 3) white women on the US mainland (white women). We analyzed differences related to ethnicity (Latina vs. white) and geography (PR vs. US mainland). RESULTS: Overall, 302 of the 3243 women (9%) enrolled in DANCE were Latina (205 of these 302 Latinas resided in PR). Significant differences were observed in 7 of 11 baseline characteristics. White women had more prior fragility fractures and family history of hip fracture than Latinas, while PR Latinas were generally older than US Latinas and had more comorbid conditions. A similar proportion of subjects in each cohort had received prior osteoporosis therapy. Physicians prescribed teriparatide more often for Latinas based on multiple risk factors for fracture and intolerance to previous osteoporosis therapy and to white women based on inadequate response to previous therapy or new (incident) fractures. Overall, Latinas were less persistent with teriparatide therapy than white women. CONCLUSION: We observed significant differences related to ethnicity and geography in the baseline demographics of Latinas enrolled in the DANCE study, criteria cited by physicians for initiating teriparatide therapy, and treatment persistence.

Assessing the Effects of Teriparatide Treatment on Bone Mineral Density, Bone Microarchitecture, and Bone Strength.

BACKGROUND: To gain insight into how teriparatide affects various bone health parameters, we assessed the effects of teriparatide treatment with use of standard DXA (dual x-ray absorptiometry) technology and two newer technologies, high-resolution MRI (magnetic resonance imaging) and finite element analysis of quantitative CT (computed tomography) scans. METHODS: In this phase-4, open-label study, postmenopausal women with severe osteoporosis received 20 µg/day of teriparatide. Assessments included (1) changes in areal BMD (bone mineral density) (in g/cm2) at the radius, spine, and hip on DXA, (2) changes in volumetric BMD (in mg/cm3) at the spine and hip on quantitative CT scans, (3) changes in bone microarchitecture at the radius on high-resolution MRI, (4) estimated changes in spine and hip strength according to finite element analysis of quantitative CT scans, (5) changes in bone turnover markers in serum, and (6) safety. RESULTS: Thirty-five subjects were enrolled; thirty completed eighteen months and twenty-five completed an optional six-month extension. No significant changes were observed for the primary outcome, high-resolution MRI at the distal aspect of the radius. At month eighteen, the least-squares mean percentage change from baseline in total volumetric BMD at the spine was 10.05% (95% confidence interval [CI], 6.83% to 13.26%; p < 0.001), and estimated spine strength increased 17.43% (95% CI, 12.09% to 22.76%; p < 0.001). Total volumetric BMD at the hip increased 2.22% (95% CI, 0.37% to 4.06%; p = 0.021), and estimated hip strength increased 2.54% (95% CI, 0.06% to 5.01%; p = 0.045). Areal BMD increased at the lumbar spine and femoral neck, was unchanged for the total hip and at the distalmost aspect of the radius, and decreased at a point one-third of the distance between the wrist and elbow. Bone turnover markers increased at months three, six, and twenty-four (all p < 0.05). No unexpected adverse events were observed. CONCLUSIONS: High-resolution MRI failed to identify changes in bone microarchitecture at the distal aspect of the radius, a non-weight-bearing site that may not be suitable for assessing effects of an osteoanabolic agent. Teriparatide increased areal BMD at the spine and femoral neck and volumetric BMD at the spine and hip. Estimated vertebral and femoral strength also increased. These findings and increases in bone turnover markers through month twenty-four are consistent with the known osteoanabolic effect of teriparatide. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Skeletal histomorphometry in subjects on teriparatide or zoledronic acid therapy (SHOTZ) study: a randomized controlled trial.

CONTEXT: Recent studies on the mechanism of action (MOA) of bone-active drugs have rekindled interest in how to present and interpret dynamic histomorphometric parameters of bone remodeling. OBJECTIVE: We compared the effects of an established anabolic agent, teriparatide (TPTD), with those of a prototypical antiresorptive agent, zoledronic acid (ZOL). DESIGN: This was a 12-month, randomized, double-blind, active-comparator controlled, cross-sectional biopsy study. SETTING: The study was conducted at 12 U.S. and Canadian centers. SUBJECTS: Healthy postmenopausal women with osteoporosis participated in the study. INTERVENTIONS: Subjects received TPTD 20 µg once daily by sc injection (n = 34) or ZOL 5 mg by iv infusion at baseline (n = 35). MAIN OUTCOME MEASURES: The primary end point was mineralizing surface/bone surface (MS/BS), a dynamic measure of bone formation, at month 6. A standard panel of dynamic and static histomorphometric indices was also assessed. When specimens with missing labels were encountered, several methods were used to calculate mineral apposition rate (MAR). Serum markers of bone turnover were also measured. RESULTS: Among 58 subjects with evaluable biopsies (TPTD = 28; ZOL = 30), MS/BS was significantly higher in the TPTD group (median: 5.60 vs. 0.16%, P < 0.001). Other bone formation indices, including MAR, were also higher in the TPTD group (P < 0.05). TPTD significantly increased procollagen type 1 N-terminal propeptide (PINP) at months 1, 3, 6, and 12 and carboxyterminal cross-linking telopeptide of collagen type 1 (CTX) from months 3 to 12. ZOL significantly decreased PINP and CTX below baseline at all time points. CONCLUSIONS: TPTD and ZOL possess fundamentally different mechanisms of action with opposite effects on bone formation based on this analysis of both histomorphometric data and serum markers of bone formation and resorption. An important mechanistic difference was a substantially higher MS/BS in the TPTD group. Overall, these results define the dynamic histomorphometric characteristics of anabolic activity relative to antiresorptive activity after treatment with these two drugs.

Changes observed in radionuclide bone scans during and after teriparatide treatment for osteoporosis.

PURPOSE: Visual changes on radionuclide bone scans have been reported with teriparatide treatment. To assess this, serial studies were evaluated and quantified in ten postmenopausal women with osteoporosis treated with teriparatide (20 µg/day subcutaneous) who had (99m)Tc-methylene diphosphonate (MDP) bone scans (baseline, 3 and 18 months, then after 6 months off therapy). METHODS: Women were injected with 600 MBq (99m)Tc-MDP, and diagnostic bone scan images were assessed at 3.5 h. Additional whole-body scans (10 min, 1, 2, 3 and 4 h) were analysed for (99m)Tc-MDP skeletal plasma clearance (K(bone)). Regional K(bone) differences were obtained for the whole skeleton and six regions (calvarium, mandible, spine, pelvis, upper and lower extremities). Bone turnover markers (BTM) were also measured. RESULTS: Most subjects showed visual changes on 3- and 18-month bone scan images that disappeared after 6 months off therapy. Enhanced uptake was seen predominantly in the calvarium and lower extremities. Whole skeleton K(bone) displayed a median increase of 22% (3 months, p = 0.004) and 34% (18 months, p = 0.002) decreasing to 0.7% (6 months off therapy). Calvarium K(bone) changes were three times larger than other sites. After 6 months off therapy, all K(bone) and BTM values returned towards baseline. CONCLUSION: The increased (99m)Tc-MDP skeletal uptake with teriparatide indicated increased bone formation which was supported by BTM increases. After 6 months off therapy, metabolic activity diminished towards baseline. The modulation of (99m)Tc-MDP skeletal uptake during treatment was the result of teriparatide's metabolic activity. These findings may aid the radiological evaluation of similar teriparatide patients having radionuclide bone scans.