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Effect of Romosozumab vs. Alendronate on Osteoporosis Fracture Risk
Study Overview
Objective. To determine if romosuzumab, an antisclerostin antibody, is superior to alendronate in reducing the incidence of fracture in postmenopausal women with osteoporosis at high-risk for fracture.
Design. Multicenter, international, double-blind, randomized clinical trial.
Setting and participants. 4093 postmenopausal women with osteoporosis and a previous fragility fracture were enrolled from over 40 countries worldwide. Patients were eligible for the study if they were 55 to 90 years old and were deemed at high risk for future fracture based on bone mineral density (BMD) T score at the total hip or femoral neck and fracture history. This included T score ≤ –2.5 and ≥ 1 moderate or severe vertebral fractures or ≥ 2 mild vertebral fractures; T score ≤ –2.0 and either ≥ 2 moderate or severe vertebral fractures or proximal femur fracture within 3 to 24 months before randomization. Subjects with a history of prior use of medications that affect bone metabolism were excluded, as were those with other metabolic bone disease, vitamin D deficiency, uncontrolled metabolic disease, malabsorption syndromes, history of transplant, severe renal insufficiency, malignancy or severe illness.
Intervention. Patients were randomized to either subcutaneous romosuzumab 210 mg monthly or oral alendronate 70 mg weekly for 12 months. Following the 12-month double-blind period, all patients received open-label weekly alendronate until the end of the trial, with maintenance of blinding to the initial treatment assignment. Primary analysis occurred when all subjects had completed the 24-month visit and clinical fractures had been confirmed in at least 330 patients. All patients received daily calcium and vitamin D. Lateral radiographs of the thoracic and lumbar spine were obtained at screening and months 12 and 24. The BMD at the lumbar spine and proximal femur was evaluated by dual-energy x-ray absorptiometry at baseline and every 12 months thereafter. Serum concentrations of bone-turnover markers were measured in a subgroup of patients.
Main outcome measures. The primary outcomes were the incidence of new vertebral fracture and the incidence of clinical fracture at 24 months. Clinical fractures included symptomatic vertebral fracture and nonvertebral fractures. The secondary outcomes were the BMD at the lumbar spine, total hip, and femoral neck at 12 and 24 months, the incidence of nonvertebral fracture, and fracture category. Safety outcomes included the incidence of adjudicated clinical events, including serious cardiovascular adverse events, osteonecrosis of the jaw, and atypical femoral fracture. Serious cardiovascular events were defined as cardiac ischemic event, cerebrovascular event, heart failure, death, non-coronary revascularization and peripheral vascular ischemic event not requiring revascularization.
Analysis. An intention to treat approach was used for data analysis. For the incidence of fractures, the treatment groups were compared using a Cox proportional-hazards model and the Mantel-Haenszel method with adjustment for age (< 75 vs ≥ 75 years), the presence or absence of severe vertebral fracture at baseline, and baseline BMD T score at the total hip. Between-group comparisons of the percentage change in BMD from baseline were analyzed by means of a repeated-measures model with adjustment for treatment, age category, baseline severe vertebral fracture, visit, treatment-by-visit interaction, and baseline BMD. Percentage changes from baseline in bone turnover were assessed using a Wilcoxon rank-sum test. The safety analysis included cumulated incidence rates of adverse outcomes. Odds ratios and confidence intervals were estimated for serious cardiovascular adverse events with the use of a logistic regression model.
Main results. 2046 participants were randomized to the romosozumab group and 2047 to the alendronate group. A total of 3654 participants from both groups (89.3%) completed 12 months of the trial, and 3150 (77.0%) completed the primary analysis period. The treatment groups were similar in baseline age, ethnicity, and fracture history. The majority of patients in both groups were non-Hispanic (> 60%) and ≥ 75 years old (> 50%). The mean age of the patients was 74.3 years. Baseline mean bone mineral density T scores were –2.96 at the lumbar spine, –2.8 at the total hip, and –2.9 at the femoral neck.
After 24 months of treatment, 6.2% of patients in the romosozumab-alendronate group had a new vertebral fracture as compared to 11.9% in the alendronate-alendronate group. This represents a 48% lower risk (risk ratio 0.52, 95% confidence interval [CI] 0.4–0.66; P < 0.001) of new vertebral fractures with romosozumab. At the time of the primary analysis, romosozumab followed by alendronate resulted in a 27% lower risk of clinical fracture than alendronate alone (hazard ratio 0.73, 95% CI 0.61–0.88; P < 0.001). 8.7% of the romosozumab-alendronate group had a nonvertebral fracture versus 10.6% in the alendronate-alendronate group, representing a 19% lower risk with romosozumab (hazard ratio 0.81, 95% CI 0.66–0.99; P = 0.04). Hip fractures occurred in 2.0% of the romosozumab-alendronate group as compared with 3.2% in the alendronate-alendronate group, representing a 38% lower risk with romosozumab (hazard ratio 0.62, 95% CI 0.42–0.92; P
Patients in the romosozumab-alendronate group had greater gains in BMD from baseline at the lumbar spine (14.9% vs 8.5%) and total hip (7% vs 3.6%) compared to the alendronate-alendronate group. (P < 0.001 for all comparisons). At 12 months, romosozumab treatment resulted in decreased levels of bone resorption marker β-CTX and increased levels of bone formation marker P1NP. β-CTX and P1NP decreased and remained below baseline levels after transitioning to alendronate. In the alendronate-alendronate group, P1NP and β-CTX decreased within 1 month and remained below baseline levels at 36 months.
Overall, the adverse events and serious event rates were similar between the 2 treatment groups during the double-blind period with 2 exceptions. In the first 12 months, injection-site reactions were reported in 4.4% of patients receiving romosozumab compared to 2.6% in those receiving alendronate. Patients in the romosozumab group had an increased incidence of adjudicated serious cardiovascular outcomes during the double-blind period, 2.5% (50 of 2040 patients) compared to 1.9% (38 of 2014 patients) in the alendronate group. During the open-label period, osteonecrosis of the jaw occurred in one patient in each group. Two atypical femoral fractures occurred in the romosozumab-alendronate group, compared to 4 in the alendronate-alendronate group. During the first 18 months of the study, binding anti-romosozumab antibodies were observed in 15.3% of the romosozumab group, with neutralizing antibodies in 0.6%.
Conclusion. In postmenopausal woman with osteoporosis and high fracture risk, 12 months of romosozumab treatment followed by alendronate resulted in significantly lower risk of fracture than use of alendronate alone.
Commentary
Osteoporosis-related fragility fractures carry a substantial risk of morbidity and mortality [1]. The goal of osteoporosis treatment is to ameliorate this risk. The current FDA-approved medications for osteoporosis can be divided into anabolic (teriparatide, abaloparatide) and anti-resorptive (bisphosphonate, denosumab, selective estrogen receptor modulators) categories. Sclerostin is a glycoprotein produced by osteocytes that inhibits the Wnt signaling pathway, thereby impeding osteoblast proliferation and activity. Romosozumab is a monoclonal antisclerostin antibody that results in both increased bone formation and decreased bone resorption [1]. By apparently uncoupling bone formation and resorption to increase bone mass, this medication holds promise to become the ideal osteoporosis drug.
Initial studies have shown that 12 months of romosozumab treatment significantly increased BMD at the lumbar spine (+11.3%), as compared to placebo (–0.1%), alendronate (+4.1%), and teriparatide (+7.1%) [2]. The Fracture Study in Postmenopausal Women with Osteoporosis (FRAME) was a large (7180 patients) randomized controlled trial that demonstrated that 12 months of romosozumab resulted in a 73% lower risk of vertebral fracture and 36% lower risk of clinical fracture compared to placebo [3]. However, there was no significant reduction in non-vertebral facture [3]. This may be due to the fact that FRAME excluded women at the highest risk for fracture. That is, exclusion criteria included history of hip fracture, any severe vertebral facture, or more than 2 moderate vertebral fractures. The current phase 3 ARCH trial (Active-Controlled Fracture Study in Postmenopausal Women with Osteoporosis at High Risk) attempts to clarify the potential benefit of romosozumab treatment in this very high-risk patient population, compared to a common first-line osteoporosis treatment, alendronate.
Indeed, ARCH demonstrates that sequential therapy with romosozumab followed by alendronate is superior to alendronate alone in improving BMD at all sites and preventing new vertebral, clinical, and non-vertebral fractures in postmenopausal women with osteoporosis and a history of fragility fracture. While ARCH was not designed as a cardiovascular outcomes trial, the higher rate of serious cardiovascular adverse events in the romosozumab group raises concern that romosozumab may have a negative effect on vascular tissue. Sclerostin is expressed in vascular smooth muscle [4] and upregulated at sites of vascular calcification [5]. It is possible that inhibiting sclerostin activity could alter vascular remodeling or increase vascular calcification. However, it is interesting that in the larger FRAME trial, no increase in adverse cardiovascular events was seen in the romosozumab group compared to placebo. This may be due to the fact that the average age of patients in FRAME was lower than ARCH. However, it also raises the hypothesis that alendronate itself may be protective in terms of cardiovascular risk. It has been postulated that bisphosphonates may have cardiovascular protective effects, given animal studies have demonstrated that alendronate downregulates monocyte chemoattractant protein 1 and macrophage inflammatory protein 1 [6]. However no cardioprotective benefit was seen in meta-analysis [7].
ARCH has several strengths, including its design as an international, double-blind, and randomized clinical trial. The primary outcome of cumulative fracture incidence is a hard endpoint and is clinically relevant. The intervention is simple and the results are clearly defined. The statistical assessment yields significant results. However, there are some limitations to the study. The lead author has received research support from Amgen and UCB Pharma, the makers of romosuzumab. Amgen and UCB Pharma designed the trial, and Amgen was responsible for trial oversight and data analyses per a pre-specified statistical analysis plan. An external independent data monitoring committee monitored unblinded safety data. Because there was no placebo-controlled arm, it is difficult to determine whether the unexpected cardiovascular signal was due to romosuzumab itself or a protective effect of alendronate. In addition, the majority of study participants were non-Hispanic from Central or Eastern Europe and Latin America, with only ~2% of patients from North America. As a result, ARCH findings may not be generalizable to other regional or ethnic populations. Furthermore, the majority of the patients were ≥ 75 years of age and were at very high fracture risk. It is unclear if younger patients or those with lower risk of fracture would see the same fracture prevention and BMD gain. In addition, because of the relatively short length of the trial, the durability of the metabolic bone benefit and cardiovascular risk is unknown. While the authors reported the increased anti-romosozumab antibodies in the romosozumab group had no detectable effect on efficacy or safety, given the short duration of the trial, this has not been proven.
Applications for Clinical Practice
The dual anti-resorptive and anabolic effect of romosozumab makes it an attractive and promising new osteoporosis therapy. ARCH suggests that sequential therapy with romosuzumab and alendronate is superior in terms of fracture prevention to alendronate alone in elderly postmenopausal women with osteoporosis and a history of fragility fractures, although longer term studies are needed to define the durability of this effect. While the absolute number of serious adjudicated cardiovascular events was low, the increased incidence in the romosuzumab group will likely prevent the FDA from approving this medication for widespread use at this time. Additional studies are needed to clarify the cause and magnitude of this cardiovascular risk and to determine whether prevention of fracture-associated morbidity and mortality is enough to mitigate it.
—Simona Frunza-Stefan, MD, and Hillary B. Whitlach, MD, University of Maryland School of Medicine, Baltimore, MD
1. Cummings SR, Melton IJ. Epidemiology and outcomes of osteoporotic fractures. Lancet 2002; 359:176107.
2. McClung MR, Grauer A, Boonen S, et al. Romosozumab in postmenopausal women with low bone mineral density. N Engl J Med 2014;370:412–20.
3. Cosman F, Crittenden DB, Adachi JD, et al. Romosozumab treatment in postmenopausal women with osteoporosis. N Engl J Med 2016;375:1532–43.
4. Zhu D, Mackenzie NCW, Millán JL, et al. The appearance and modulation of osteocyte marker expres- sion during calcification of vascular smooth muscle cells. PLoS One 2011;6:e19595.
5. Evenepoel P, Goffin E, Meijers B, et al. Sclerostin serum levels and vascular calcification progression in prevalent renal transplant recipients. J Clin Endocrinol Metab 2015;100:4669–76.
6. Masuda T, Deng X, Tamai R. Mouse macrophages primed with alendronate down-regulate monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) production in response to Toll-like receptor (TLR) 2 and TLR4 agonist via Smad3 activation. Int Immunopharmacol 2009;9:1115–21.
7. Kim DH, Rogers JR, Fulchino LA, et al. Bisphosphonates and risk of cardiovascular events: a meta-analysis. PLoS One 2015;10:e0122646.
Study Overview
Objective. To determine if romosuzumab, an antisclerostin antibody, is superior to alendronate in reducing the incidence of fracture in postmenopausal women with osteoporosis at high-risk for fracture.
Design. Multicenter, international, double-blind, randomized clinical trial.
Setting and participants. 4093 postmenopausal women with osteoporosis and a previous fragility fracture were enrolled from over 40 countries worldwide. Patients were eligible for the study if they were 55 to 90 years old and were deemed at high risk for future fracture based on bone mineral density (BMD) T score at the total hip or femoral neck and fracture history. This included T score ≤ –2.5 and ≥ 1 moderate or severe vertebral fractures or ≥ 2 mild vertebral fractures; T score ≤ –2.0 and either ≥ 2 moderate or severe vertebral fractures or proximal femur fracture within 3 to 24 months before randomization. Subjects with a history of prior use of medications that affect bone metabolism were excluded, as were those with other metabolic bone disease, vitamin D deficiency, uncontrolled metabolic disease, malabsorption syndromes, history of transplant, severe renal insufficiency, malignancy or severe illness.
Intervention. Patients were randomized to either subcutaneous romosuzumab 210 mg monthly or oral alendronate 70 mg weekly for 12 months. Following the 12-month double-blind period, all patients received open-label weekly alendronate until the end of the trial, with maintenance of blinding to the initial treatment assignment. Primary analysis occurred when all subjects had completed the 24-month visit and clinical fractures had been confirmed in at least 330 patients. All patients received daily calcium and vitamin D. Lateral radiographs of the thoracic and lumbar spine were obtained at screening and months 12 and 24. The BMD at the lumbar spine and proximal femur was evaluated by dual-energy x-ray absorptiometry at baseline and every 12 months thereafter. Serum concentrations of bone-turnover markers were measured in a subgroup of patients.
Main outcome measures. The primary outcomes were the incidence of new vertebral fracture and the incidence of clinical fracture at 24 months. Clinical fractures included symptomatic vertebral fracture and nonvertebral fractures. The secondary outcomes were the BMD at the lumbar spine, total hip, and femoral neck at 12 and 24 months, the incidence of nonvertebral fracture, and fracture category. Safety outcomes included the incidence of adjudicated clinical events, including serious cardiovascular adverse events, osteonecrosis of the jaw, and atypical femoral fracture. Serious cardiovascular events were defined as cardiac ischemic event, cerebrovascular event, heart failure, death, non-coronary revascularization and peripheral vascular ischemic event not requiring revascularization.
Analysis. An intention to treat approach was used for data analysis. For the incidence of fractures, the treatment groups were compared using a Cox proportional-hazards model and the Mantel-Haenszel method with adjustment for age (< 75 vs ≥ 75 years), the presence or absence of severe vertebral fracture at baseline, and baseline BMD T score at the total hip. Between-group comparisons of the percentage change in BMD from baseline were analyzed by means of a repeated-measures model with adjustment for treatment, age category, baseline severe vertebral fracture, visit, treatment-by-visit interaction, and baseline BMD. Percentage changes from baseline in bone turnover were assessed using a Wilcoxon rank-sum test. The safety analysis included cumulated incidence rates of adverse outcomes. Odds ratios and confidence intervals were estimated for serious cardiovascular adverse events with the use of a logistic regression model.
Main results. 2046 participants were randomized to the romosozumab group and 2047 to the alendronate group. A total of 3654 participants from both groups (89.3%) completed 12 months of the trial, and 3150 (77.0%) completed the primary analysis period. The treatment groups were similar in baseline age, ethnicity, and fracture history. The majority of patients in both groups were non-Hispanic (> 60%) and ≥ 75 years old (> 50%). The mean age of the patients was 74.3 years. Baseline mean bone mineral density T scores were –2.96 at the lumbar spine, –2.8 at the total hip, and –2.9 at the femoral neck.
After 24 months of treatment, 6.2% of patients in the romosozumab-alendronate group had a new vertebral fracture as compared to 11.9% in the alendronate-alendronate group. This represents a 48% lower risk (risk ratio 0.52, 95% confidence interval [CI] 0.4–0.66; P < 0.001) of new vertebral fractures with romosozumab. At the time of the primary analysis, romosozumab followed by alendronate resulted in a 27% lower risk of clinical fracture than alendronate alone (hazard ratio 0.73, 95% CI 0.61–0.88; P < 0.001). 8.7% of the romosozumab-alendronate group had a nonvertebral fracture versus 10.6% in the alendronate-alendronate group, representing a 19% lower risk with romosozumab (hazard ratio 0.81, 95% CI 0.66–0.99; P = 0.04). Hip fractures occurred in 2.0% of the romosozumab-alendronate group as compared with 3.2% in the alendronate-alendronate group, representing a 38% lower risk with romosozumab (hazard ratio 0.62, 95% CI 0.42–0.92; P
Patients in the romosozumab-alendronate group had greater gains in BMD from baseline at the lumbar spine (14.9% vs 8.5%) and total hip (7% vs 3.6%) compared to the alendronate-alendronate group. (P < 0.001 for all comparisons). At 12 months, romosozumab treatment resulted in decreased levels of bone resorption marker β-CTX and increased levels of bone formation marker P1NP. β-CTX and P1NP decreased and remained below baseline levels after transitioning to alendronate. In the alendronate-alendronate group, P1NP and β-CTX decreased within 1 month and remained below baseline levels at 36 months.
Overall, the adverse events and serious event rates were similar between the 2 treatment groups during the double-blind period with 2 exceptions. In the first 12 months, injection-site reactions were reported in 4.4% of patients receiving romosozumab compared to 2.6% in those receiving alendronate. Patients in the romosozumab group had an increased incidence of adjudicated serious cardiovascular outcomes during the double-blind period, 2.5% (50 of 2040 patients) compared to 1.9% (38 of 2014 patients) in the alendronate group. During the open-label period, osteonecrosis of the jaw occurred in one patient in each group. Two atypical femoral fractures occurred in the romosozumab-alendronate group, compared to 4 in the alendronate-alendronate group. During the first 18 months of the study, binding anti-romosozumab antibodies were observed in 15.3% of the romosozumab group, with neutralizing antibodies in 0.6%.
Conclusion. In postmenopausal woman with osteoporosis and high fracture risk, 12 months of romosozumab treatment followed by alendronate resulted in significantly lower risk of fracture than use of alendronate alone.
Commentary
Osteoporosis-related fragility fractures carry a substantial risk of morbidity and mortality [1]. The goal of osteoporosis treatment is to ameliorate this risk. The current FDA-approved medications for osteoporosis can be divided into anabolic (teriparatide, abaloparatide) and anti-resorptive (bisphosphonate, denosumab, selective estrogen receptor modulators) categories. Sclerostin is a glycoprotein produced by osteocytes that inhibits the Wnt signaling pathway, thereby impeding osteoblast proliferation and activity. Romosozumab is a monoclonal antisclerostin antibody that results in both increased bone formation and decreased bone resorption [1]. By apparently uncoupling bone formation and resorption to increase bone mass, this medication holds promise to become the ideal osteoporosis drug.
Initial studies have shown that 12 months of romosozumab treatment significantly increased BMD at the lumbar spine (+11.3%), as compared to placebo (–0.1%), alendronate (+4.1%), and teriparatide (+7.1%) [2]. The Fracture Study in Postmenopausal Women with Osteoporosis (FRAME) was a large (7180 patients) randomized controlled trial that demonstrated that 12 months of romosozumab resulted in a 73% lower risk of vertebral fracture and 36% lower risk of clinical fracture compared to placebo [3]. However, there was no significant reduction in non-vertebral facture [3]. This may be due to the fact that FRAME excluded women at the highest risk for fracture. That is, exclusion criteria included history of hip fracture, any severe vertebral facture, or more than 2 moderate vertebral fractures. The current phase 3 ARCH trial (Active-Controlled Fracture Study in Postmenopausal Women with Osteoporosis at High Risk) attempts to clarify the potential benefit of romosozumab treatment in this very high-risk patient population, compared to a common first-line osteoporosis treatment, alendronate.
Indeed, ARCH demonstrates that sequential therapy with romosozumab followed by alendronate is superior to alendronate alone in improving BMD at all sites and preventing new vertebral, clinical, and non-vertebral fractures in postmenopausal women with osteoporosis and a history of fragility fracture. While ARCH was not designed as a cardiovascular outcomes trial, the higher rate of serious cardiovascular adverse events in the romosozumab group raises concern that romosozumab may have a negative effect on vascular tissue. Sclerostin is expressed in vascular smooth muscle [4] and upregulated at sites of vascular calcification [5]. It is possible that inhibiting sclerostin activity could alter vascular remodeling or increase vascular calcification. However, it is interesting that in the larger FRAME trial, no increase in adverse cardiovascular events was seen in the romosozumab group compared to placebo. This may be due to the fact that the average age of patients in FRAME was lower than ARCH. However, it also raises the hypothesis that alendronate itself may be protective in terms of cardiovascular risk. It has been postulated that bisphosphonates may have cardiovascular protective effects, given animal studies have demonstrated that alendronate downregulates monocyte chemoattractant protein 1 and macrophage inflammatory protein 1 [6]. However no cardioprotective benefit was seen in meta-analysis [7].
ARCH has several strengths, including its design as an international, double-blind, and randomized clinical trial. The primary outcome of cumulative fracture incidence is a hard endpoint and is clinically relevant. The intervention is simple and the results are clearly defined. The statistical assessment yields significant results. However, there are some limitations to the study. The lead author has received research support from Amgen and UCB Pharma, the makers of romosuzumab. Amgen and UCB Pharma designed the trial, and Amgen was responsible for trial oversight and data analyses per a pre-specified statistical analysis plan. An external independent data monitoring committee monitored unblinded safety data. Because there was no placebo-controlled arm, it is difficult to determine whether the unexpected cardiovascular signal was due to romosuzumab itself or a protective effect of alendronate. In addition, the majority of study participants were non-Hispanic from Central or Eastern Europe and Latin America, with only ~2% of patients from North America. As a result, ARCH findings may not be generalizable to other regional or ethnic populations. Furthermore, the majority of the patients were ≥ 75 years of age and were at very high fracture risk. It is unclear if younger patients or those with lower risk of fracture would see the same fracture prevention and BMD gain. In addition, because of the relatively short length of the trial, the durability of the metabolic bone benefit and cardiovascular risk is unknown. While the authors reported the increased anti-romosozumab antibodies in the romosozumab group had no detectable effect on efficacy or safety, given the short duration of the trial, this has not been proven.
Applications for Clinical Practice
The dual anti-resorptive and anabolic effect of romosozumab makes it an attractive and promising new osteoporosis therapy. ARCH suggests that sequential therapy with romosuzumab and alendronate is superior in terms of fracture prevention to alendronate alone in elderly postmenopausal women with osteoporosis and a history of fragility fractures, although longer term studies are needed to define the durability of this effect. While the absolute number of serious adjudicated cardiovascular events was low, the increased incidence in the romosuzumab group will likely prevent the FDA from approving this medication for widespread use at this time. Additional studies are needed to clarify the cause and magnitude of this cardiovascular risk and to determine whether prevention of fracture-associated morbidity and mortality is enough to mitigate it.
—Simona Frunza-Stefan, MD, and Hillary B. Whitlach, MD, University of Maryland School of Medicine, Baltimore, MD
Study Overview
Objective. To determine if romosuzumab, an antisclerostin antibody, is superior to alendronate in reducing the incidence of fracture in postmenopausal women with osteoporosis at high-risk for fracture.
Design. Multicenter, international, double-blind, randomized clinical trial.
Setting and participants. 4093 postmenopausal women with osteoporosis and a previous fragility fracture were enrolled from over 40 countries worldwide. Patients were eligible for the study if they were 55 to 90 years old and were deemed at high risk for future fracture based on bone mineral density (BMD) T score at the total hip or femoral neck and fracture history. This included T score ≤ –2.5 and ≥ 1 moderate or severe vertebral fractures or ≥ 2 mild vertebral fractures; T score ≤ –2.0 and either ≥ 2 moderate or severe vertebral fractures or proximal femur fracture within 3 to 24 months before randomization. Subjects with a history of prior use of medications that affect bone metabolism were excluded, as were those with other metabolic bone disease, vitamin D deficiency, uncontrolled metabolic disease, malabsorption syndromes, history of transplant, severe renal insufficiency, malignancy or severe illness.
Intervention. Patients were randomized to either subcutaneous romosuzumab 210 mg monthly or oral alendronate 70 mg weekly for 12 months. Following the 12-month double-blind period, all patients received open-label weekly alendronate until the end of the trial, with maintenance of blinding to the initial treatment assignment. Primary analysis occurred when all subjects had completed the 24-month visit and clinical fractures had been confirmed in at least 330 patients. All patients received daily calcium and vitamin D. Lateral radiographs of the thoracic and lumbar spine were obtained at screening and months 12 and 24. The BMD at the lumbar spine and proximal femur was evaluated by dual-energy x-ray absorptiometry at baseline and every 12 months thereafter. Serum concentrations of bone-turnover markers were measured in a subgroup of patients.
Main outcome measures. The primary outcomes were the incidence of new vertebral fracture and the incidence of clinical fracture at 24 months. Clinical fractures included symptomatic vertebral fracture and nonvertebral fractures. The secondary outcomes were the BMD at the lumbar spine, total hip, and femoral neck at 12 and 24 months, the incidence of nonvertebral fracture, and fracture category. Safety outcomes included the incidence of adjudicated clinical events, including serious cardiovascular adverse events, osteonecrosis of the jaw, and atypical femoral fracture. Serious cardiovascular events were defined as cardiac ischemic event, cerebrovascular event, heart failure, death, non-coronary revascularization and peripheral vascular ischemic event not requiring revascularization.
Analysis. An intention to treat approach was used for data analysis. For the incidence of fractures, the treatment groups were compared using a Cox proportional-hazards model and the Mantel-Haenszel method with adjustment for age (< 75 vs ≥ 75 years), the presence or absence of severe vertebral fracture at baseline, and baseline BMD T score at the total hip. Between-group comparisons of the percentage change in BMD from baseline were analyzed by means of a repeated-measures model with adjustment for treatment, age category, baseline severe vertebral fracture, visit, treatment-by-visit interaction, and baseline BMD. Percentage changes from baseline in bone turnover were assessed using a Wilcoxon rank-sum test. The safety analysis included cumulated incidence rates of adverse outcomes. Odds ratios and confidence intervals were estimated for serious cardiovascular adverse events with the use of a logistic regression model.
Main results. 2046 participants were randomized to the romosozumab group and 2047 to the alendronate group. A total of 3654 participants from both groups (89.3%) completed 12 months of the trial, and 3150 (77.0%) completed the primary analysis period. The treatment groups were similar in baseline age, ethnicity, and fracture history. The majority of patients in both groups were non-Hispanic (> 60%) and ≥ 75 years old (> 50%). The mean age of the patients was 74.3 years. Baseline mean bone mineral density T scores were –2.96 at the lumbar spine, –2.8 at the total hip, and –2.9 at the femoral neck.
After 24 months of treatment, 6.2% of patients in the romosozumab-alendronate group had a new vertebral fracture as compared to 11.9% in the alendronate-alendronate group. This represents a 48% lower risk (risk ratio 0.52, 95% confidence interval [CI] 0.4–0.66; P < 0.001) of new vertebral fractures with romosozumab. At the time of the primary analysis, romosozumab followed by alendronate resulted in a 27% lower risk of clinical fracture than alendronate alone (hazard ratio 0.73, 95% CI 0.61–0.88; P < 0.001). 8.7% of the romosozumab-alendronate group had a nonvertebral fracture versus 10.6% in the alendronate-alendronate group, representing a 19% lower risk with romosozumab (hazard ratio 0.81, 95% CI 0.66–0.99; P = 0.04). Hip fractures occurred in 2.0% of the romosozumab-alendronate group as compared with 3.2% in the alendronate-alendronate group, representing a 38% lower risk with romosozumab (hazard ratio 0.62, 95% CI 0.42–0.92; P
Patients in the romosozumab-alendronate group had greater gains in BMD from baseline at the lumbar spine (14.9% vs 8.5%) and total hip (7% vs 3.6%) compared to the alendronate-alendronate group. (P < 0.001 for all comparisons). At 12 months, romosozumab treatment resulted in decreased levels of bone resorption marker β-CTX and increased levels of bone formation marker P1NP. β-CTX and P1NP decreased and remained below baseline levels after transitioning to alendronate. In the alendronate-alendronate group, P1NP and β-CTX decreased within 1 month and remained below baseline levels at 36 months.
Overall, the adverse events and serious event rates were similar between the 2 treatment groups during the double-blind period with 2 exceptions. In the first 12 months, injection-site reactions were reported in 4.4% of patients receiving romosozumab compared to 2.6% in those receiving alendronate. Patients in the romosozumab group had an increased incidence of adjudicated serious cardiovascular outcomes during the double-blind period, 2.5% (50 of 2040 patients) compared to 1.9% (38 of 2014 patients) in the alendronate group. During the open-label period, osteonecrosis of the jaw occurred in one patient in each group. Two atypical femoral fractures occurred in the romosozumab-alendronate group, compared to 4 in the alendronate-alendronate group. During the first 18 months of the study, binding anti-romosozumab antibodies were observed in 15.3% of the romosozumab group, with neutralizing antibodies in 0.6%.
Conclusion. In postmenopausal woman with osteoporosis and high fracture risk, 12 months of romosozumab treatment followed by alendronate resulted in significantly lower risk of fracture than use of alendronate alone.
Commentary
Osteoporosis-related fragility fractures carry a substantial risk of morbidity and mortality [1]. The goal of osteoporosis treatment is to ameliorate this risk. The current FDA-approved medications for osteoporosis can be divided into anabolic (teriparatide, abaloparatide) and anti-resorptive (bisphosphonate, denosumab, selective estrogen receptor modulators) categories. Sclerostin is a glycoprotein produced by osteocytes that inhibits the Wnt signaling pathway, thereby impeding osteoblast proliferation and activity. Romosozumab is a monoclonal antisclerostin antibody that results in both increased bone formation and decreased bone resorption [1]. By apparently uncoupling bone formation and resorption to increase bone mass, this medication holds promise to become the ideal osteoporosis drug.
Initial studies have shown that 12 months of romosozumab treatment significantly increased BMD at the lumbar spine (+11.3%), as compared to placebo (–0.1%), alendronate (+4.1%), and teriparatide (+7.1%) [2]. The Fracture Study in Postmenopausal Women with Osteoporosis (FRAME) was a large (7180 patients) randomized controlled trial that demonstrated that 12 months of romosozumab resulted in a 73% lower risk of vertebral fracture and 36% lower risk of clinical fracture compared to placebo [3]. However, there was no significant reduction in non-vertebral facture [3]. This may be due to the fact that FRAME excluded women at the highest risk for fracture. That is, exclusion criteria included history of hip fracture, any severe vertebral facture, or more than 2 moderate vertebral fractures. The current phase 3 ARCH trial (Active-Controlled Fracture Study in Postmenopausal Women with Osteoporosis at High Risk) attempts to clarify the potential benefit of romosozumab treatment in this very high-risk patient population, compared to a common first-line osteoporosis treatment, alendronate.
Indeed, ARCH demonstrates that sequential therapy with romosozumab followed by alendronate is superior to alendronate alone in improving BMD at all sites and preventing new vertebral, clinical, and non-vertebral fractures in postmenopausal women with osteoporosis and a history of fragility fracture. While ARCH was not designed as a cardiovascular outcomes trial, the higher rate of serious cardiovascular adverse events in the romosozumab group raises concern that romosozumab may have a negative effect on vascular tissue. Sclerostin is expressed in vascular smooth muscle [4] and upregulated at sites of vascular calcification [5]. It is possible that inhibiting sclerostin activity could alter vascular remodeling or increase vascular calcification. However, it is interesting that in the larger FRAME trial, no increase in adverse cardiovascular events was seen in the romosozumab group compared to placebo. This may be due to the fact that the average age of patients in FRAME was lower than ARCH. However, it also raises the hypothesis that alendronate itself may be protective in terms of cardiovascular risk. It has been postulated that bisphosphonates may have cardiovascular protective effects, given animal studies have demonstrated that alendronate downregulates monocyte chemoattractant protein 1 and macrophage inflammatory protein 1 [6]. However no cardioprotective benefit was seen in meta-analysis [7].
ARCH has several strengths, including its design as an international, double-blind, and randomized clinical trial. The primary outcome of cumulative fracture incidence is a hard endpoint and is clinically relevant. The intervention is simple and the results are clearly defined. The statistical assessment yields significant results. However, there are some limitations to the study. The lead author has received research support from Amgen and UCB Pharma, the makers of romosuzumab. Amgen and UCB Pharma designed the trial, and Amgen was responsible for trial oversight and data analyses per a pre-specified statistical analysis plan. An external independent data monitoring committee monitored unblinded safety data. Because there was no placebo-controlled arm, it is difficult to determine whether the unexpected cardiovascular signal was due to romosuzumab itself or a protective effect of alendronate. In addition, the majority of study participants were non-Hispanic from Central or Eastern Europe and Latin America, with only ~2% of patients from North America. As a result, ARCH findings may not be generalizable to other regional or ethnic populations. Furthermore, the majority of the patients were ≥ 75 years of age and were at very high fracture risk. It is unclear if younger patients or those with lower risk of fracture would see the same fracture prevention and BMD gain. In addition, because of the relatively short length of the trial, the durability of the metabolic bone benefit and cardiovascular risk is unknown. While the authors reported the increased anti-romosozumab antibodies in the romosozumab group had no detectable effect on efficacy or safety, given the short duration of the trial, this has not been proven.
Applications for Clinical Practice
The dual anti-resorptive and anabolic effect of romosozumab makes it an attractive and promising new osteoporosis therapy. ARCH suggests that sequential therapy with romosuzumab and alendronate is superior in terms of fracture prevention to alendronate alone in elderly postmenopausal women with osteoporosis and a history of fragility fractures, although longer term studies are needed to define the durability of this effect. While the absolute number of serious adjudicated cardiovascular events was low, the increased incidence in the romosuzumab group will likely prevent the FDA from approving this medication for widespread use at this time. Additional studies are needed to clarify the cause and magnitude of this cardiovascular risk and to determine whether prevention of fracture-associated morbidity and mortality is enough to mitigate it.
—Simona Frunza-Stefan, MD, and Hillary B. Whitlach, MD, University of Maryland School of Medicine, Baltimore, MD
1. Cummings SR, Melton IJ. Epidemiology and outcomes of osteoporotic fractures. Lancet 2002; 359:176107.
2. McClung MR, Grauer A, Boonen S, et al. Romosozumab in postmenopausal women with low bone mineral density. N Engl J Med 2014;370:412–20.
3. Cosman F, Crittenden DB, Adachi JD, et al. Romosozumab treatment in postmenopausal women with osteoporosis. N Engl J Med 2016;375:1532–43.
4. Zhu D, Mackenzie NCW, Millán JL, et al. The appearance and modulation of osteocyte marker expres- sion during calcification of vascular smooth muscle cells. PLoS One 2011;6:e19595.
5. Evenepoel P, Goffin E, Meijers B, et al. Sclerostin serum levels and vascular calcification progression in prevalent renal transplant recipients. J Clin Endocrinol Metab 2015;100:4669–76.
6. Masuda T, Deng X, Tamai R. Mouse macrophages primed with alendronate down-regulate monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) production in response to Toll-like receptor (TLR) 2 and TLR4 agonist via Smad3 activation. Int Immunopharmacol 2009;9:1115–21.
7. Kim DH, Rogers JR, Fulchino LA, et al. Bisphosphonates and risk of cardiovascular events: a meta-analysis. PLoS One 2015;10:e0122646.
1. Cummings SR, Melton IJ. Epidemiology and outcomes of osteoporotic fractures. Lancet 2002; 359:176107.
2. McClung MR, Grauer A, Boonen S, et al. Romosozumab in postmenopausal women with low bone mineral density. N Engl J Med 2014;370:412–20.
3. Cosman F, Crittenden DB, Adachi JD, et al. Romosozumab treatment in postmenopausal women with osteoporosis. N Engl J Med 2016;375:1532–43.
4. Zhu D, Mackenzie NCW, Millán JL, et al. The appearance and modulation of osteocyte marker expres- sion during calcification of vascular smooth muscle cells. PLoS One 2011;6:e19595.
5. Evenepoel P, Goffin E, Meijers B, et al. Sclerostin serum levels and vascular calcification progression in prevalent renal transplant recipients. J Clin Endocrinol Metab 2015;100:4669–76.
6. Masuda T, Deng X, Tamai R. Mouse macrophages primed with alendronate down-regulate monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) production in response to Toll-like receptor (TLR) 2 and TLR4 agonist via Smad3 activation. Int Immunopharmacol 2009;9:1115–21.
7. Kim DH, Rogers JR, Fulchino LA, et al. Bisphosphonates and risk of cardiovascular events: a meta-analysis. PLoS One 2015;10:e0122646.