Treatment with denosumab reduces the incidence of new vertebral and hip fractures in postmenopausal women at high risk

The FREEDOM (Fracture REduction Evaluation of Denosumab in Osteoporosis every 6 Months) trial showed denosumab significantly reduced the risk of fractures in postmenopausal women with osteoporosis.

Denosumab Significantly Increases DXA BMD at Both Trabecular and Cortical Sites: Results From the FREEDOM Study

Denosumab is an approved therapy for postmenopausal women with osteoporosis at high or increased risk for fracture. In the FREEDOM study, denosumab reduced fracture risk and increased bone mineral density (BMD). We report the spine and hip dual-energy X-ray absorptiometry (DXA) BMD responses from the overall study of 7808 women and from a substudy of 441 participants in which more extensive spine and hip assessments as well as additional skeletal sites were evaluated. Significant BMD improvements were observed as early as 1mo at the lumbar spine, total hip, and trochanter (all p<0.005 vs placebo and baseline). BMD increased progressively at the lumbar spine, total hip, femoral neck, trochanter, 1/3 radius, and total body from baseline to months 12, 24, and 36 (all p<0.005 vs placebo and baseline). BMD gains above the least significant change of more than 3% at 36 months were observed in 90% of denosumab-treated subjects at the lumbar spine and 74% at the total hip, and gains more than 6% occurred in 77% and 38%, respectively. In conclusion, denosumab treatment resulted in significant, early, and continued BMD increases at both trabecular and cortical sites throughout the skeleton over 36mo with important gains observed in most subjects.

CECOG experts' recommendations on the use of denosumab in the prevention of skeletal-related events in bone metastases of lung cancer

Purpose Skeletal-related events represent a substantial burden for patients with advanced cancer. Randomized, controlled studies suggested superiority of denosumab over zoledronic acid in the prevention of skeletal-related events in metastatic cancer patients, with a favorable safety profile. Experts gathered at the 2012 Skeletal Care Academy in Istanbul to bring forward practical recommendations, based on current evidence, for the use of denosumab in patients with bone metastases of lung cancer. Recommendations Based on current evidence, use of denosumab in lung cancer patients with confirmed bone metastases is recommended. It is important to note that clinical judgment should take into consideration the patient’s general performance status, overall prognosis, and live expectancy. Currently, the adverse event profile reported for denosumab includes hypocalcemia and infrequent occurrence of osteonecrosis of the jaw. Therefore, routine calcium and vitamin D supplementation, along with dental examination prior to denosumab initiation are recommended. There is no evidence for renal function impairment due to denosumab administration. At present, there is no rationale to discourage concomitant use of denosumab and surgery or radiotherapy.

Further reductions in nonvertebral fracture rate with long-term denosumab treatment in the FREEDOM open-label extension and influence of hip bone mineral density after 3 years

Limited data exist on the efficacy of long-term therapies for osteoporosis. In osteoporotic postmenopausal women receiving denosumab for 7 years, nonvertebral fracture rates significantly decreased in years 4-7 versus years 1-3. This is the first demonstration of a further benefit on fracture outcomes with long-term therapy for osteoporosis. INTRODUCTION This study aimed to evaluate whether denosumab treatment continued beyond 3 years is associated with a further reduction in nonvertebral fracture rates. METHODS Participants who completed the 3-year placebo-controlled Fracture REduction Evaluation of Denosumab in Osteoporosis every 6 Months (FREEDOM) study were invited to participate in an open-label extension. The present analysis includes 4,074 postmenopausal women with osteoporosis (n = 2,343 long-term; n = 1,731 cross-over) who enrolled in the extension, missed ≤1 dose during their first 3 years of denosumab treatment, and continued into the fourth year of treatment. Comparison of nonvertebral fracture rates during years 1-3 of denosumab with that of the fourth year and with the rate during years 4-7 was evaluated. RESULTS For the combined group, the nonvertebral fracture rate per 100 participant-years was 2.15 for the first 3 years of denosumab treatment (referent) and 1.36 in the fourth year (rate ratio [RR] = 0.64; 95 % confidence interval (CI) = 0.48 to 0.85, p = 0.003). Comparable findings were observed in the groups separately and when nonvertebral fracture rates during years 1-3 were compared to years 4-7 in the long-term group (RR = 0.79; 95 % CI = 0.62 to 1.00, p = 0.046). Fracture rate reductions in year 4 were most prominent in subjects with persisting low hip bone mineral density (BMD). CONCLUSIONS Denosumab treatment beyond 3 years was associated with a further reduction in nonvertebral fracture rate that persisted through 7 years of continuous denosumab administration. The degree to which denosumab further reduces nonvertebral fracture risk appears influenced by the hip bone density achieved with initial therapy.

The effect of 8 or 5 years of denosumab treatment in postmenopausal women with osteoporosis: results from the FREEDOM Extension study

UNLABELLED The FREEDOM study and its Extension provide long-term information about the effects of denosumab for the treatment of postmenopausal osteoporosis. Treatment for up to 8 years was associated with persistent reduction of bone turnover, continued increases in bone mineral density, low fracture incidence, and a favorable benefit/risk profile. INTRODUCTION This study aims to report the results through year 5 of the FREEDOM Extension study, representing up to 8 years of continued denosumab treatment in postmenopausal women with osteoporosis. METHODS Women who completed the 3-year FREEDOM study were eligible to enter the 7-year open-label FREEDOM Extension in which all participants are scheduled to receive denosumab, since placebo assignment was discontinued for ethical reasons. A total of 4550 women enrolled in the Extension (2343 long-term; 2207 cross-over). In this analysis, women in the long-term and cross-over groups received denosumab for up to 8 and 5 years, respectively. RESULTS Throughout the Extension, sustained reduction of bone turnover markers (BTMs) was observed in both groups. In the long-term group, mean bone mineral density (BMD) continued to increase significantly at each time point measured, for cumulative 8-year gains of 18.4 and 8.3 % at the lumbar spine and total hip, respectively. In the cross-over group, mean BMD increased significantly from the Extension baseline for 5-year cumulative gains of 13.1 and 6.2 % at the lumbar spine and total hip, respectively. The yearly incidence of new vertebral and nonvertebral fractures remained low in both groups. The incidence of adverse and serious adverse events did not increase over time. Through Extension year 5, eight events of osteonecrosis of the jaw and two events of atypical femoral fracture were confirmed. CONCLUSIONS Denosumab treatment for up to 8 years was associated with persistent reductions of BTMs, continued BMD gains, low fracture incidence, and a consistent safety profile.

Rebound-associated vertebral fractures after discontinuation of denosumab-from clinic and biomechanics.

Rebound-associated vertebral fractures may follow treatment discontinuation of highly potent reversible bone antiresorptives, resulting from the synergy of rapid bone resorption and accelerated microdamage accumulation in trabecular bone. INTRODUCTION The purposes of this study are to characterize rebound-associated vertebral fractures following the discontinuation of a highly potent reversible antiresorptive therapy based on clinical observation and propose a pathophysiological rationale. METHODS This study is a case report of multiple vertebral fractures early after discontinuation of denosumab therapy in a patient with hormone receptor-positive non-metastatic breast cancer treated with an aromatase inhibitor. RESULTS Discontinuation of highly potent reversible bone antiresorptives such as denosumab may expose patients to an increased fracture risk due to the joined effects of absent microdamage repair during therapy followed by synchronous excess activation of multiple bone remodelling units at the time of loss-of-effect. We suggest the term rebound-associated vertebral fractures (RVF) for this phenomenon characterized by the presence of multiple new clinical vertebral fractures, associated with either no or low trauma, in a context consistent with the presence of high bone turnover and rapid loss of lumbar spine bone mineral density (BMD) occurring within 3 to 12 months after discontinuation (loss-of-effect) of a reversible antiresorptive therapy in the absence of secondary causes of bone loss or fractures. Unlike atypical femoral fractures that emerge from failure of microdamage repair in cortical bone with long-term antiresorptive treatment, RVF originate from the synergy of rapid bone resorption and accelerated microdamage accumulation in trabecular bone triggered by the discontinuation of highly potent reversible antiresorptives. CONCLUSIONS Studies are urgently needed to i) prove the underlying pathophysiological processes suggested above, ii) establish the predictive criteria exposing patients to an increased risk of RVF, and iii) determine appropriate treatment regimens to be applied in such patients.

The future of osteoporosis treatment - a research update

Osteoporosis is characterised by a progressive loss of bone mass and microarchitecture which leads to increased fracture risk. Some of the drugs available to date have shown reductions in vertebral and non-vertebral fracture risk. However, in the ageing population of industrialised countries, still more fractures happen today than are avoided, which highlights the large medical need for new treatment options, models, and strategies. Recent insights into bone biology, have led to a better understanding of bone cell functions and crosstalk between osteoblasts, osteoclasts, and osteocytes at the molecular level. In the future, the armamentarium against osteoporotic fractures will likely be enriched by (1.) new bone anabolic substances such as antibodies directed against the endogenous inhibitors of bone formation sclerostin and dickkopf-1, PTH and PTHrp analogues, and possibly calcilytics; (2.) new inhibitors of bone resorption such as cathepsin K inhibitors which may suppress osteoclast function without impairing osteoclast viability and thus maintain bone formation by preserving the osteoclast-osteoblast crosstalk, and denosumab, an already widely available antibody against RANKL which inhibits osteoclast formation, function, and survival; and (3.) new therapeutic strategies based on an extended understanding of the pathophysiology of osteoporosis which may include sequential therapies with two or more bone active substances aimed at optimising the management of bone capital acquired during adolescence and maintained during adulthood in terms of both quantity and quality. Finally, one of the future challenges will be to identify those patients and patient populations expected to benefit the most from a given drug therapy or regimen. The WHO fracture risk assessment tool FRAX® and improved access to bone mineral density measurements by DXA will play a key role in this regard.

[Bone metastasis in prostate cancer]

Bone metastasis and skeletal complications have a devastating impact on the quality of life and are a major cause of morbidity in prostate cancer patients. In addition to established bone-targeted therapies, new drugs such as endothelin A receptor antagonists, MET and VEGFR-2 antagonists or radiopharmaceuticals are in the focus of development. The standard care in prostate cancer patients with bone metastases to prevent skeletal-related events (SRE) are bisphosphonates. Denosumab, a human monoclonal antibody against RANKL, appeared to be superior to zoledronic acid for prevention of SRE and has been shown to prolong bone metastases-free survival. In contrast to zoledronic acid, denosumab clearance is not dependent on kidney function and can be administered subcutaneously. Similar rates of toxicity were observed for both substances; however, long-term data for denosumab are limited.

Comparison of proximal femur and vertebral body strength improvements in the FREEDOM trial using an alternative finite element methodology

Denosumab reduced the incidence of new fractures in postmenopausal women with osteoporosis by 68% at the spine and 40% at the hip over 36 months compared with placebo in the FREEDOM study. This efficacy was supported by improvements from baseline in vertebral (18.2%) strength in axial compression and femoral (8.6%) strength in sideways fall configuration at 36 months, estimated in Newtons by an established voxel-based finite element (FE) methodology. Since FE analyses rely on the choice of meshes, material properties, and boundary conditions, the aim of this study was to independently confirm and compare the effects of denosumab on vertebral and femoral strength during the FREEDOM trial using an alternative smooth FE methodology. Unlike the previous FE study, effects on femoral strength in physiological stance configuration were also examined. QCT data for the proximal femur and two lumbar vertebrae were analyzed by smooth FE methodology at baseline, 12, 24, and 36 months for 51 treated (denosumab) and 47 control (placebo) subjects. QCT images were segmented and converted into smooth FE models to compute bone strength. L1 and L2 vertebral bodies were virtually loaded in axial compression and the proximal femora in both fall and stance configurations. Denosumab increased vertebral body strength by 10.8%, 14.0%, and 17.4% from baseline at 12, 24, and 36 months, respectively (p < 0.0001). Denosumab also increased femoral strength in the fall configuration by 4.3%, 5.1%, and 7.2% from baseline at 12, 24, and 36 months, respectively (p < 0.0001). Similar improvements were observed in the stance configuration with increases of 4.2%, 5.2%, and 5.2% from baseline (p ≤ 0.0007). Differences between the increasing strengths with denosumab and the decreasing strengths with placebo were significant starting at 12 months (vertebral and femoral fall) or 24 months (femoral stance). Using an alternative smooth FE methodology, we confirmed the significant improvements in vertebral body and proximal femur strength previously observed with denosumab. Estimated increases in strength with denosumab and decreases with placebo were highly consistent between both FE techniques.