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).

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.

Fracture and Bone Mineral Density Response by Baseline Risk in Patients Treated With Abaloparatide Followed by Alendronate: Results From the Phase 3 ACTIVExtend Trial.

In the randomized, placebo-controlled, double-blind phase 3 ACTIVE study (NCT01343004), 18 months of abaloparatide 80 µg daily (subcutaneous injection) in postmenopausal women at risk of osteoporotic fracture significantly reduced the risk of vertebral, nonvertebral, clinical, and major osteoporotic fractures and significantly increased bone mineral density (BMD) versus placebo regardless of baseline risk factors. Women from the abaloparatide and placebo groups who completed ACTIVE were eligible for ACTIVExtend (NCT01657162), in which all enrollees received sequential, open-label monotherapy with alendronate 70 mg once weekly for up to 24 months. This prespecified analysis evaluated whether fracture risk reductions and bone mineral density (BMD) gains associated with abaloparatide during ACTIVE persisted through the full 43-month ACTIVE-ACTIVExtend study period in nine prespecified baseline risk subgroups. Baseline risk subgroups included BMD T-score at the lumbar spine, total hip, and femoral neck (≤ - 2.5 versus > - 2.5 and ≤ -3.0 versus > - 3.0), history of nonvertebral fracture (yes/no), prevalent vertebral fracture (yes/no), and age (<65 versus 65 to <75 versus ≥75 years). Forest plots display treatment effect. Treatment-by-subgroup interactions were tested using the Breslow-Day test, Cox proportional hazards model, and ANCOVA model. After the combined ACTIVE-ACTIVExtend study period, reductions in relative risk for new vertebral, nonvertebral, clinical, and major osteoporotic fractures were greater among patients in the abaloparatide/alendronate group than among those in the placebo/alendronate group across all nine baseline risk subgroups. BMD gains at the lumbar spine, total hip, and femoral neck were greater in the abaloparatide/alendronate group versus the placebo/alendronate group. No clinically meaningful interaction between treatment assignment and any baseline risk variable was observed. The sequence of abaloparatide for 18 months followed by alendronate for up to 24 months appears to be an effective treatment option for a wide range of postmenopausal women at risk for osteoporotic fractures. © 2019 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals, Inc.

Parathyroid Hormone and Parathyroid Hormone-Related Protein Analogs in Osteoporosis Therapy.

PURPOSE OF REVIEW: The purpose is to review the efficacy and optimal use of parathyroid hormone and parathyroid hormone-related protein analogs in osteoporosis treatment. RECENT FINDINGS: The parathyroid hormone analog teriparatide, a potent stimulator of bone remodeling, increases hip and spine bone mineral density and reduces the risk of vertebral and non-vertebral fractures in postmenopausal osteoporotic women. The parathyroid hormone-related protein analog, abaloparatide, also reduces fracture incidence but has pharmacological effects that differ from teriparatide, particularly in cortical bone. These analogs provide maximal benefit when their use is followed by a potent antiresorptive medication. Moreover, studies have shown that the combination of teriparatide and the RANK-ligand inhibitor, denosumab, increase bone density and estimated strength more than monotherapy and more than any currently available regimen. Parathyroid hormone and parathyroid hormone-related protein analogs, whether as monotherapy, in combination with antiresorptive agents or in sequence with antiresorptive agents, will likely play an expanding role in osteoporosis management.

Gonadal steroid-dependent effects on bone turnover and bone mineral density in men.

BACKGROUND: Severe gonadal steroid deficiency induces bone loss in adult men; however, the specific roles of androgen and estrogen deficiency in hypogonadal bone loss are unclear. Additionally, the threshold levels of testosterone and estradiol that initiate bone loss are uncertain. METHODS: One hundred ninety-eight healthy men, ages 20-50, received goserelin acetate, which suppresses endogenous gonadal steroid production, and were randomized to treatment with 0, 1.25, 2.5, 5, or 10 grams of testosterone gel daily for 16 weeks. An additional cohort of 202 men was randomized to receive these treatments plus anastrozole, which suppresses conversion of androgens to estrogens. Thirty-seven men served as controls and received placebos for goserelin and testosterone. Changes in bone turnover markers, bone mineral density (BMD) by dual-energy x-ray absorptiometry (DXA), and BMD by quantitative computed tomography (QCT) were assessed in all men. Bone microarchitecture was assessed in 100 men. RESULTS: As testosterone dosage decreased, the percent change in C-telopeptide increased. These increases were considerably greater when aromatization of testosterone to estradiol was also suppressed, suggesting effects of both testosterone and estradiol deficiency. Decreases in DXA BMD were observed when aromatization was suppressed but were modest in most groups. QCT spine BMD fell substantially in all testosterone-dose groups in which aromatization was also suppressed, and this decline was independent of testosterone dose. Estradiol deficiency disrupted cortical microarchitecture at peripheral sites. Estradiol levels above 10 pg/ml and testosterone levels above 200 ng/dl were generally sufficient to prevent increases in bone resorption and decreases in BMD in men. CONCLUSIONS: Estrogens primarily regulate bone homeostasis in adult men, and testosterone and estradiol levels must decline substantially to impact the skeleton. TRIAL REGISTRATION: ClinicalTrials.gov, NCT00114114. FUNDING: AbbVie Inc., AstraZeneca Pharmaceuticals LP, NIH.

Effects of abaloparatide, a human parathyroid hormone-related peptide analog, on bone mineral density in postmenopausal women with osteoporosis.

CONTEXT: Abaloparatide is a novel synthetic peptide analog of parathyroid hormone-related protein (PTHrP) that is currently being developed as a potential anabolic agent in the treatment of postmenopausal osteoporosis. OBJECTIVE: This study sought to assess the effects of abaloparatide on bone mineral density (BMD) at the lumbar spine, total hip, and femoral neck in postmenopausal women with osteoporosis. DESIGN: Multi-center, multi-national, double-blind placebo controlled trial in which postmenopausal women were randomly assigned to receive 24 weeks of treatment with daily sc injections of placebo, abaloparatide, 20, 40, or 80 µg, or teriparatide, 20 µg. A 24-week extension was also performed in a subset of subjects. PARTICIPANTS: Postmenopausal women with osteoporosis (n = 222). MAIN OUTCOME MEASURES: BMD by dual-x-ray absorptiometry and biochemical markers of bone turnover. RESULTS: At 24 weeks, lumbar spine BMD increased by 2.9, 5.2, and 6.7% in the abaloparatide, 20-, 40-, and 80-µg groups, respectively, and 5.5% in the teriparatide group. The increases in the 40- and 80-µg abaloparatide groups and the teriparatide group were significantly greater than placebo (1.6%). Femoral neck BMD increased by 2.7, 2.2, and 3.1% in abaloparatide, 20-, 40-, and 80-µg groups, respectively, and 1.1% in the teriparatide group. The increase in femoral neck BMD with abaloparatide, 80 µg was significantly greater than placebo (0.8%). Total hip BMD increased by 1.4, 2.0, and 2.6% in the abaloparatide, 20-, 40-, and 80-µg groups, respectively. The total hip increases in the 40- and 80-µg abaloparatide groups were greater than both placebo (0.4%) and teriparatide (0.5%). CONCLUSIONS: Compared with placebo, 24 weeks of daily sc abaloparatide increases BMD of the lumbar spine, femoral neck, and total hip in a dose-dependent fashion. Moreover, the abaloparatide-induced BMD increases at the total hip are greater than with the marketed dose of teriparatide. These results support the further investigation of abaloparatide as an anabolic therapy in postmenopausal osteoporosis.

Effects of escitalopram on markers of bone turnover: a randomized clinical trial.

CONTEXT: Recent observational studies have suggested that the use of selective serotonin reuptake inhibitors is associated with an increased fracture risk and an accelerated bone loss, although conflicting results have been reported. Furthermore, because many of these studies have been performed in depressed women, confounding by indication may influence these findings. OBJECTIVE: The objective of the study was to determine whether selective serotonin reuptake inhibitors affect bone metabolism Design: This was a randomized controlled trial. SETTING: The study was conducted in four US clinical sites. PARTICIPANTS: Healthy peri- and postmenopausal women participated in the study. INTERVENTION: The intervention was escitalopram (10-20 mg/d) for the treatment of vasomotor symptoms. MAIN OUTCOME MEASURES: Serum carboxyterminal collagen crosslinks (CTX) and serum amino-terminal propeptide of type I collagen (P1NP) were measured. RESULTS: One hundred forty-one peri- or postmenopausal nondepressed women (mean age 53.7 y, SD 4.1) had baseline and 8-week follow-up samples available for analysis and were included in the study (69 escitalopram, 72 placebo). The groups were balanced across a broad range of baseline characteristics, including age, race, body mass index, smoking status, and mood symptoms. The between-group differences in the change in CTX and P1NP from baseline to week 8 were compared by a repeated-measures linear regression model adjusted for race, clinical center, and baseline measurement. Treatment with escitalopram reduced serum P1NP by 1.02 ng/mL on average [95% confidence interval (CI) -5.17, 3.12] compared with a reduction of 1.88 ng/mL (95% CI -4.82, 1.06) in the placebo group (P = .65). Similarly, serum CTX decreased 0.02 ng/mL on average (95% CI -0.05, 0.01) in the escitalopram group compared with 0.00 ng/mL (95% CI -0.02, 0.02) in the placebo group (P = .24). The results were similar when the analysis was restricted to those women whose adherence to study medication was 70% or greater. CONCLUSIONS: Although the study was limited to 8 weeks, these results suggest that escitalopram does not significantly alter bone metabolism in the short term.

FSH suppression does not affect bone turnover in eugonadal men.

CONTEXT: In vitro and animal studies have reported conflicting results regarding an independent role for FSH in the regulation of bone turnover. OBJECTIVE: Our objective was to test the hypothesis that suppressing serum FSH while holding serum gonadal steroid levels stable in the eugonadal range will affect biochemical markers of bone metabolism in healthy men. PARTICIPANTS, DESIGN, AND SETTING: Eugonadal men aged 20 to 50 years participated in this randomized controlled trial at a tertiary care academic teaching hospital. INTERVENTIONS: Participants received monthly GnRH analog injections to suppress FSH secretion plus daily topical testosterone gel in prespecified doses (intervention group). Controls received matching placebos (control group). Subjects in the intervention group were individually matched with subjects in the control group to ensure that the mean testosterone and estradiol levels (measured every 4 weeks during the 16-week study period) in the 2 groups were similar. MAIN OUTCOME MEASURES: Biochemical markers of bone resorption (serum N-terminal telopeptide and C-terminal telopeptide), bone formation (serum osteocalcin), and FSH were measured at baseline and after 16 weeks of treatment. RESULTS: Serum FSH declined by 2% in the control group and by 60% in the intervention group (P < .0001 for the between-group difference). Despite the substantial suppression of serum FSH in the intervention group, serum N-terminal telopeptide, C-terminal telopeptide, and osteocalcin did not change in the intervention group, nor were any between-group differences observed. CONCLUSION: When gonadal steroid levels are held constant, short-to midterm suppression of FSH does not affect bone turnover in men. FSH does not appear to be a significant regulator of bone metabolism in eugonadal men.

Teriparatide (PTH 1-34) treatment increases peripheral hematopoietic stem cells in postmenopausal women.

Cells of the osteoblast lineage play an important role in regulating the hematopoietic stem cell (HSC) niche and early B-cell development in animal models, perhaps via parathyroid hormone (PTH)-dependent mechanisms. There are few human clinical studies investigating this phenomenon. We studied the impact of long-term daily teriparatide (PTH 1-34) treatment on cells of the hematopoietic lineage in postmenopausal women. Twenty-three postmenopausal women at high risk of fracture received teriparatide 20 mcg sc daily for 24 months as part of a prospective longitudinal trial. Whole blood measurements were obtained at baseline, 3, 6, 12, and 18 months. Flow cytometry was performed to identify hematopoietic subpopulations, including HSCs (CD34+/CD45(moderate); ISHAGE protocol) and early transitional B cells (CD19+, CD27-, IgD+, CD24[hi], CD38[hi]). Serial measurements of spine and hip bone mineral density (BMD) as well as serum P1NP, osteocalcin, and CTX were also performed. The average age of study subjects was 64 ± 5 years. We found that teriparatide treatment led to an early increase in circulating HSC number of 40% ± 14% (p = 0.004) by month 3, which persisted to month 18 before returning to near baseline by 24 months. There were no significant changes in transitional B cells or total B cells over the course of the study period. In addition, there were no differences in complete blood count profiles as quantified by standard automated flow cytometry. Interestingly, the peak increase in HSC number was inversely associated with increases in bone markers and spine BMD. Daily teriparatide treatment for osteoporosis increases circulating HSCs by 3 to 6 months in postmenopausal women. This may represent a proliferation of marrow HSCs or increased peripheral HSC mobilization. This clinical study establishes the importance of PTH in the regulation of the HSC niche within humans. © 2014 American Society for Bone and Mineral Research.

Gonadal steroids and body composition, strength, and sexual function in men.

BACKGROUND: Current approaches to diagnosing testosterone deficiency do not consider the physiological consequences of various testosterone levels or whether deficiencies of testosterone, estradiol, or both account for clinical manifestations. METHODS: We provided 198 healthy men 20 to 50 years of age with goserelin acetate (to suppress endogenous testosterone and estradiol) and randomly assigned them to receive a placebo gel or 1.25 g, 2.5 g, 5 g, or 10 g of testosterone gel daily for 16 weeks. Another 202 healthy men received goserelin acetate, placebo gel or testosterone gel, and anastrozole (to suppress the conversion of testosterone to estradiol). Changes in the percentage of body fat and in lean mass were the primary outcomes. Subcutaneous- and intraabdominal-fat areas, thigh-muscle area and strength, and sexual function were also assessed. RESULTS: The percentage of body fat increased in groups receiving placebo or 1.25 g or 2.5 g of testosterone daily without anastrozole (mean testosterone level, 44±13 ng per deciliter, 191±78 ng per deciliter, and 337±173 ng per deciliter, respectively). Lean mass and thigh-muscle area decreased in men receiving placebo and in those receiving 1.25 g of testosterone daily without anastrozole. Leg-press strength fell only with placebo administration. In general, sexual desire declined as the testosterone dose was reduced. CONCLUSIONS: The amount of testosterone required to maintain lean mass, fat mass, strength, and sexual function varied widely in men. Androgen deficiency accounted for decreases in lean mass, muscle size, and strength; estrogen deficiency primarily accounted for increases in body fat; and both contributed to the decline in sexual function. Our findings support changes in the approach to evaluation and management of hypogonadism in men. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT00114114.).

Anabolic therapies for osteoporosis.

As the first FDA-approved anabolic agent for osteoporosis, teriparatide has proven effective for people at highest risk of fracture, despite limitations of expense, route of delivery, and length of treatment. Available data show that combination therapy with teriparatide and antiresorptive agents does not offer a therapeutic advantage. However, treatment with an antiresorptive agent after teriparatide discontinuation is essential to prevent the ensuing bone loss. Although pretreatment with bisphosphonates may somewhat attenuate the anabolic effect of teriparatide, significant gains in bone mineral density are still achieved and prior bisphosphonate use should not dissuade clinicians from using teriparatide in select patients.

Sarcopenia during androgen-deprivation therapy for prostate cancer.

PURPOSE: To characterize changes in lean body mass (LBM) in men with prostate cancer receiving androgen-deprivation therapy (ADT). PATIENTS AND METHODS: We prospectively evaluated LBM in a prespecified substudy of a randomized controlled trial of denosumab to prevent fractures in men receiving ADT for nonmetastatic prostate cancer. LBM was measured by total-body dual-energy x-ray absorptiometry at study baseline and at 12, 24, and 36 months. The analyses included 252 patients (132, denosumab; 120, placebo) with a baseline and at least one on-study LBM assessment. Patients were stratified by age (< 70 v ≥ 70 years) and by ADT duration (≤ 6 v > 6 months). RESULTS: Median ADT duration was 20.4 months at study baseline. Mean LBM decreased significantly from baseline, by 1.0% at month 12 (95% CI, 0.4% to 1.5%; P < .001; n = 248), by 2.1% at month 24 (95% CI, 1.5% to 2.7%; P < .001; n = 205), and by 2.4% at month 36 (95% CI, 1.6% to 3.2%; P < .001; n = 168). Men age ≥ 70 years (n = 127) had significantly greater changes in LBM at all measured time points than younger men. At 36 months, LBM decreased by 2.8% in men age ≥ 70 years and by 0.9% in younger men (P = .035). Men with ≤ 6 months of ADT at study entry (n = 36) had a greater rate of decrease in LBM compared with men who had received more than 6 months of ADT at study entry (3.7% v 2.0%; P = .0645). CONCLUSION: In men receiving ADT, LBM decreased significantly after 12, 24, and 36 months.

Denosumab and changes in bone turnover markers during androgen deprivation therapy for prostate cancer.

Androgen deprivation therapy (ADT) for prostate cancer increases fracture risk, decreases bone mineral density, and increases bone turnover markers (BTMs) including serum type 1 C-telopeptide (sCTX), tartrate-resistant alkaline phosphatase 5b (TRAP-5b), and procollagen-1 N-terminal telopeptide (P1NP). In a prespecified exploratory analysis of a phase 3, multicenter, double-blind study, we evaluated the effects of denosumab (60 mg subcutaneously every 6 months for 3 years) versus placebo (1468 patients, 734 in each group) on BTM values. BTMs were measured at baseline, month 1, and predose at months 6, 12, 24, and 36 in the overall population. BTMs at month 1 are also reported for subgroups based on age (< 70 years versus ≥ 70 years), prior duration of ADT (≤ 6 months versus > 6 months), and baseline BTM (≤ median versus > median BTM values). Treatment with denosumab provided a rapid and sustained decrease of BTM values compared with placebo. The median change in sCTX levels at month 1 was -90% in the denosumab group and -3% in the placebo group (p < 0.0001). The median change in TRAP-5b levels at month 1 was -55% in the denosumab group and -3% in the placebo group (p < 0.0001). The maximal median change in P1NP was -64% in the denosumab group and -11% in the placebo group, (p < 0.0001). Significantly greater decreases in BTM for denosumab were also seen in subgroup analyses based on age, prior ADT treatment, and baseline BTM values. Suppression of bone turnover markers was consistent with marked increases in bone mineral density reported previously.

Acute decline in serum sclerostin in response to PTH infusion in healthy men.

CONTEXT: Animal models suggest that the osteoblast-stimulating actions of PTH are mediated by acute suppression of sclerostin, an inhibitor of the anabolic Wnt pathway. The immediate physiological changes in serum sclerostin in response to PTH infusion have not been reported in human studies. OBJECTIVE: We sought to determine the acute physiological effects of PTH infusion on serum sclerostin and bone turnover markers in healthy adult men. DESIGN, SETTING, AND PARTICIPANTS: Fifty-three healthy adult men underwent an 18-h iv infusion of human PTH(1-34) at a dose of 0.55 U/kg · h. OUTCOMES: Serum levels of ionized calcium, sclerostin, and markers of bone formation (osteocalcin and amino-terminal propeptide of type I procollagen) and bone resorption (C-telopeptide and N-telopeptide) were obtained at 0, 6, 12, and 18 h. RESULTS: Serum ionized calcium, C-telopeptide, and N-telopeptide increased, and osteocalcin and amino-terminal propeptide of type I procollagen fell linearly throughout the PTH infusion (P < 0.001 for all). Average ± sem sclerostin levels declined from 936 ± 65 to 813 ± 63 pg/ml at 6 h (P < 0.001) and remained stably suppressed for the duration of the PTH infusion. There were no significant correlations between change in sclerostin and change in bone markers. CONCLUSIONS: Serum sclerostin declined in response to acute PTH infusion within 6 h in healthy adult men. The early plateau in sclerostin suppression may indicate that maximal stimulation of the Wnt pathway is achieved quickly after exposure to PTH. Our findings support the hypothesis that PTH may mediate its anabolic effects in part via suppression of sclerostin.

Effects of aromatase inhibition on bone mineral density and bone turnover in older men with low testosterone levels.

CONTEXT: Aging is associated with declining gonadal steroid production, low bone mineral density (BMD), and fragility fractures. The efficacy and safety of testosterone replacement in older men remains uncertain. OBJECTIVE: The objective of the study was to assess the effects of aromatase inhibition on BMD in older men with low testosterone levels. DESIGN AND SETTING: This was a 1-yr, double-blind, randomized, placebo-controlled trial that was conducted at a tertiary care academic center in Boston, MA. PARTICIPANTS: Participants included 69 men aged 60+ yr with borderline or low testosterone levels and hypogonadal symptoms. INTERVENTION: Intervention included 1 mg anastrozole daily or placebo. MAIN OUTCOME MEASURES: Changes in gonadal steroid hormone levels, BMD, and bone turnover markers were measured. RESULTS: Mean serum testosterone increased from 319 +/- 93 ng/dl at baseline to 524+/-139 ng/dl at month 3 (P < 0.0001) and declined slightly to 474 +/- 145 ng/dl by 1 yr. Estradiol levels decreased from 15 +/- 4 pg/ml at baseline to 12 +/- 4 pg/ml at month 3 and then remained stable (P < 0.0001). Posterior-anterior (PA) spine BMD decreased in the anastrozole group as compared with placebo (P = 0.0014). In the anastrozole group, PA spine BMD decreased from 1.121 +/- 0.141 g/cm(2) to 1.102 +/- 0.138 g/cm(2), whereas in the placebo group, PA spine BMD increased from 1.180 +/- 0.145 g/cm(2) to 1.189 +/- 0.146 g/cm(2). Qualitatively similar, but not statistically significant, changes occurred at the other sites. Bone turnover markers were not affected by anastrozole therapy. CONCLUSIONS: In older men, aromatase inhibition increases testosterone levels, decreases estradiol levels, and appears to decrease BMD. Aromatase inhibition does not improve skeletal health in aging men with low or low normal testosterone levels.

Effects of denosumab on bone mineral density in men receiving androgen deprivation therapy for prostate cancer.

PURPOSE: In a recently completed 3-year, randomized, double-blind study, denosumab, a fully human monoclonal antibody against receptor activator of nuclear factor kappaB ligand, significantly increased bone mineral density and decreased new vertebral fractures in men receiving androgen deprivation therapy for prostate cancer. We conducted subgroup analyses to evaluate the relationships between subject characteristics and the effects of denosumab on bone mineral density at multiple skeletal sites. MATERIALS AND METHODS: A total of 1,468 subjects were randomized 1:1 to receive 60 mg subcutaneous denosumab every 6 months or placebo for 36 months. In these analyses we evaluated the effects of denosumab on bone mineral density at the lumbar spine, total hip and distal 1/3 radius (substudy of 309 subjects) during 36 months in specific subgroups according to age, duration and type of prior androgen deprivation therapy, bone mineral density T score, weight, body mass index, bone turnover marker levels and prevalent vertebral fractures. RESULTS: After 36 months denosumab significantly increased bone mineral density of the lumbar spine, total hip and distal 1/3 radius by 7.9%, 5.7% and 6.9%, respectively, compared with placebo (p <0.0001 for each comparison). Denosumab significantly increased bone mineral density to a degree similar to that observed in the overall analysis for every subgroup including older men as well as those with prevalent fractures, lower baseline bone mineral density, and higher serum C-telopeptide and tartrate-resistant alkaline phosphatase 5b. Mean increases in bone mineral density at each skeletal site were greatest for men with the highest levels of serum C-telopeptide and tartrate-resistant alkaline phosphatase 5b. CONCLUSIONS: Denosumab significantly and consistently increased bone mineral density at all skeletal sites and in every subgroup, including men at greatest risk for bone loss and fractures.

Denosumab in men receiving androgen-deprivation therapy for prostate cancer.

BACKGROUND: Androgen-deprivation therapy is well-established for treating prostate cancer but is associated with bone loss and an increased risk of fracture. We investigated the effects of denosumab, a fully human monoclonal antibody against receptor activator of nuclear factor-kappaB ligand, on bone mineral density and fractures in men receiving androgen-deprivation therapy for nonmetastatic prostate cancer. METHODS: In this double-blind, multicenter study, we randomly assigned patients to receive denosumab at a dose of 60 mg subcutaneously every 6 months or placebo (734 patients in each group). The primary end point was percent change in bone mineral density at the lumbar spine at 24 months. Key secondary end points included percent change in bone mineral densities at the femoral neck and total hip at 24 months and at all three sites at 36 months, as well as incidence of new vertebral fractures. RESULTS: At 24 months, bone mineral density of the lumbar spine had increased by 5.6% in the denosumab group as compared with a loss of 1.0% in the placebo group (P<0.001); significant differences between the two groups were seen at as early as 1 month and sustained through 36 months. Denosumab therapy was also associated with significant increases in bone mineral density at the total hip, femoral neck, and distal third of the radius at all time points. Patients who received denosumab had a decreased incidence of new vertebral fractures at 36 months (1.5%, vs. 3.9% with placebo) (relative risk, 0.38; 95% confidence interval, 0.19 to 0.78; P=0.006). Rates of adverse events were similar between the two groups. CONCLUSIONS: Denosumab was associated with increased bone mineral density at all sites and a reduction in the incidence of new vertebral fractures among men receiving androgen-deprivation therapy for nonmetastatic prostate cancer. (ClinicalTrials.gov number, NCT00089674.)

Effects of hPTH(1-34) infusion on circulating serum phosphate, 1,25-dihydroxyvitamin D, and FGF23 levels in healthy men.

Fibroblast growth factor 23 (FGF23) promotes phosphaturia and suppresses 1,25-dihydroxyvitamin D [1,25(OH)(2)D] production. PTH also promotes phosphaturia, but, in contrast, stimulates 1,25(OH)(2)D production. The relationship between FGF23 and PTH is unclear, and the acute effect of pharmacologically dosed PTH on FGF23 secretion is unknown. Twenty healthy men were infused with human PTH(1-34) [hPTH(1-34)] at 44 ng/kg/h for 24 h. Compared with baseline, FGF23, 1,25(OH)(2)D, ionized calcium (iCa), and serum N-telopeptide (NTX) increased significantly over the 18-h hPTH(1-34) infusion (p < 0.0001), whereas serum phosphate (PO(4)) transiently increased and then returned to baseline. FGF23 increased from 35 +/- 10 pg/ml at baseline to 53 +/- 20 pg/ml at 18 h (p = 0.0002); 1,25(OH)(2)D increased from 36 +/- 16 pg/ml at baseline to 80 +/- 33 pg/ml at 18 h (p < 0.0001); iCa increased from 1.23 +/- 0.03 mM at baseline to 1.46 +/- 0.05 mM at hour 18 (p < 0.0001); and NTX increased from 17 +/- 4 nM BCE at baseline to 28 +/- 8 nM BCE at peak (p < 0.0001). PO(4) was 3.3 +/- 0.6 mg/dl at baseline, transiently rose to 3.7 +/- 0.4 mg/dl at hour 6 (p = 0.016), and then returned to 3.4 +/- 0.5 mg/dl at hour 12 (p = 0.651). hPTH(1-34) infusion increases endogenous 1,25(OH)(2)D and FGF23 within 18 h in healthy men. Whereas it is possible that the rise in PO(4) contributed to the observed increase in FGF23, the increase in 1,25(OH)(2)D was more substantial and longer sustained than the change in serum phosphate. Given prior data that suggest that neither PTH nor calcium stimulate FGF23 secretion, these data support the assertion that 1,25(OH)(2)D is a potent physiologic stimulator of FGF23 secretion.

Relation between serum testosterone, serum estradiol, sex hormone-binding globulin, and geometrical measures of adult male proximal femur strength.

CONTEXT: Although previous studies have indicated associations between circulating testosterone (T) or estradiol (E2) concentrations and bone mineral density, the relationship between gonadal steroids and skeletal geometry is not well defined. OBJECTIVE: Our objective was to uncover the relation between circulating T or E2 and proximal femur geometry in a diverse sample of men. DESIGN: We used data on 808 men enrolled in the Boston Area Community Health/Bone Study. Serum concentrations of total and calculated free T and E2 were obtained via early-morning blood sampling. The geometry of the proximal femur at three sites (the narrow neck, intertrochanter, and shaft) was obtained using the Hip Structural Analysis technology. Analyses adjusted for subjects' age, height, total body lean mass and fat mass, and level of physical activity were performed. SETTING: In-home interviews accompanied by subject visits to the General Clinical Research Center at Boston University School of Medicine were performed. STUDY PARTICIPANTS: A randomly selected cohort of men living in Boston, MA (ages 30-79 yr) was included in the study. INTERVENTIONS: These were not applicable. MAIN OUTCOME MEASURES: Bone mineral density and bone outer diameter, cross-sectional area (measuring bone material), and section modulus (an index of bending strength) were calculated. RESULTS: In age-adjusted models, E2 was positively associated with hip strength parameters, whereas T was not. Adjustment for age and other parameters resulted in substantial reductions in, but not complete elimination of, associations between E2 and hip strength parameters. CONCLUSION: Circulating E2 is strongly associated with proximal femur strength, an association that is partially mediated by body composition.