The FDA is requiring a boxed warning in the label of denosumab (Prolia – Amgen), a monoclonal antibody that inhibits osteoclasts, about an increased risk of severe hypocalcemia in patients with advanced chronic kidney disease (CKD; eGFR <30 mL/min/1.73 m²), particularly those on dialysis. FDA-approved indications for Prolia are listed in Table 1.

US guidelines recommend pharmacologic therapy for postmenopausal women with a bone density T-score (standard deviation from normal mean values in healthy young women) of -2.5 or below in the lumbar spine, femoral neck, total hip, or distal radius, a T-score between -1.0 and -2.5 and a history of fragility (low-trauma) fracture of the hip or spine, or a T-score between -1.0 and -2.5 and a FRAX 10-year probability of ≥3% for hip fracture or ≥20% for major osteoporotic fracture (hip, clinical spine, humerus, distal radius).

View the Comparison Table: Some Drugs for Postmenopausal Osteoporosis

The FDA has approved romosozumab-aqqg (Evenity – Amgen), a sclerostin inhibitor, for once-monthly subcutaneous (SC) treatment of osteoporosis in postmenopausal women who are at high risk for fracture (history of osteoporotic fracture or multiple risk factors for fracture) or who have failed or cannot tolerate other drugs for this indication. Romosozumab is the first sclerostin inhibitor to be approved in the US and the third drug for treatment of postmenopausal osteoporosis that stimulates bone formation; the parathyroid hormone (PTH) receptor agonists abaloparatide (Tymlos) and teriparatide (Forteo) were approved earlier. Other drugs used for treatment of postmenopausal osteoporosis, such as bisphosphonates, inhibit bone resorption and decrease bone turnover.

Diagnosis of osteoporosis is based on the results of bone mineral density (BMD) testing or by the occurrence of a fragility fracture. Bone densitometry results are generally reported in terms of standard deviations (SD) from the mean value for young adults (T-score). The World Health Organization (WHO) defines osteoporosis in women as a T-score of -2.5 or below in the spine, femoral neck, or total hip. A computerized model (FRAX) is available that estimates the 10-year probability of a hip fracture or other major osteoporotic fracture based on clinical risk factors and BMD at the femoral neck.

View the Comparison Table: Drugs for Postmenopausal Osteoporosis

US guidelines for the treatment of osteoporosis have been published. The diagnosis of osteoporosis has traditionally been established by the occurrence of fragility fractures or by bone densitometry, which is generally reported in terms of standard deviations (SD) from mean values in young adults (T-score). The World Health Organization (WHO) has defined normal bone mineral density (BMD) for women as a value within one SD of the young adult mean. Values 2.5 SD or more below the mean (T-score -2.5 or below) at the spine, femoral neck, or total hip are defined as osteoporosis. The WHO has developed a computerized model (FRAX) that predicts the 10-year probability of a hip fracture or other major osteoporotic fracture based on clinical risk factors and BMD at the femoral neck.

Radium Ra 223 dichloride (Xofigo – Bayer), a radiotherapeutic drug, has been approved by the FDA for intravenous treatment of castration-resistant prostate cancer with symptomatic bone metastases and no known visceral metastatic disease.

Osteoporosis is characterized by low bone mass with microarchitectural disruption and skeletal fragility that results in an increased risk of fracture. The diagnosis has traditionally been established by bone densitometry, which is generally reported in terms of standard deviations (SD) from mean values in young adults (T-score). The World Health Organization (WHO) has defined normal bone mineral density (BMD) for women as a value within one SD of the young adult mean. Values 2.5 SD or more below the mean (T score -2.5) are defined as osteoporosis. The WHO has developed a computerized model (FRAX) that predicts the 10-year probability of a hip fracture or any other major osteoporotic fracture based on clinical risk factors and BMD at the femoral neck.

The FDA, which recently approved subcutaneous (SC) administration of denosumab (Prolia – Amgen) for treatment of postmenopausal osteoporosis,1 has now approved the same drug with a different brand name (Xgeva – Amgen) and dosage for prevention of skeletal-related events (such as pathologic fracture, spinal cord compression or radiation to bone) in patients with bone metastases from solid tumors. Denosumab is a fully human anti-RANK ligand antibody that inhibits the formation, activation and survival of osteoclasts.2

A prospective, randomized, double-blind trial in 1901 patients with bone metastases from castration-resistant prostate cancer found that denosumab 120 mg injected SC every 4 weeks, compared to the bisphosphonate zoledronic acid (Zometa) 4 mg IV, delayed the time to a first skeletal event by 3.6 months (20.7 vs. 17.1 months).3 In 1776 patients with bone metastases from solid tumors or multiple myeloma, the mean time to a first skeletal event was 20.6 months with SC denosumab and 16.3 months with IV zoledronic acid.4

Denosumab can lower serum calcium concentrations, especially in patients with impaired renal function. Fatigue is the most commonly reported adverse effect. Other adverse effects of both denosumab and zoledronic acid in clinical trials have included nausea, dyspnea and diarrhea. Acute-phase reactions and renal toxicity have been less frequent with denosumab than with zoledronic acid. Osteonecrosis of the jaw, which can occur with bisphosphonates, has also been reported with denosumab.

1. Denosumab (Prolia) for postmenopausal osteoporosis. Med Lett Drugs Ther 2010; 52: 81.

2. A Lipton and C Goessl. Clinical development of anti-RANKL therapies for treatment and prevention of bone metastasis. Bone 2011; 48:96.

3. K Fizazi et al. A randomized phase III trial of denosumab versus zoledronic acid in patients with bone metastases from castration-resistant prostate cancer. J Clin Oncol 2010; 28:18s (abstr LBA4507).

4. D Henry et al. A double-blind, randomized study of denosumab versus zoledronic acid for the treatment of bone metastases in patients with advanced cancer (excluding breast and prostate cancer) or multiple myeloma. Eur J Cancer Suppl 2009; 7:11 (abstr 20LBA).

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The FDA has approved use of denosumab (Prolia – Amgen) for treatment of osteoporosis in postmenopausal women at high risk for fracture.

Osteoporosis is characterized by low bone mass with microarchitectural disruption and skeletal fragility that results in an increased risk of fracture. The diagnosis has traditionally been established by bone densitometry, which is generally reported in terms of standard deviations (SD) from mean values in young adults (T score). The World Health Organization (WHO) has defined normal bone mineral density (BMD) for women as a value within one SD of the young adult mean. Values 2.5 SD (T score -2.5) or more below the mean are defined as osteoporosis. The WHO has developed a computerized model (FRAX) that predicts the 10-year probability of hip fracture based on clinical risk factors and BMD at the femoral neck.