Transition From Alendronate to Romosozumab (AMG 785)

An Open-label, Randomized Study to Estimate the Percent Change From Baseline in Lumbar Spine Bone Mineral Density After 3 Months of AMG 785 Administration in Postmenopausal Women With Low Bone Mineral Density Previously Treated With Alendronate

The purpose of this study is to estimate the percent change from baseline in lumbar spine bone mineral density (BMD) following multiple-dose administrations of romosozumab in postmenopausal women with low BMD previously treated with alendronate.

Inclusion Criteria:

• Postmenopausal women, defined as no vaginal bleeding or spotting for ≥ 12 months
• Low bone mineral density at screening [defined by a bone mineral density (BMD) T-score ≤ -2.0 and ≥ -4.0 at the lumbar spine (L1 to L4; or BMD T-score of evaluable vertebrae), total hip, or femoral neck]
• Currently taking alendronate (70 mg weekly or equivalent) exclusively for ≥ 1 year with verbal agreement that the subject has taken ≥ 80% of their doses with good tolerance

Exclusion Criteria:

• History of vertebral fracture, or fragility fracture of the wrist, humerus, hip or pelvis after age 50; or recent bone fracture within 6 months prior to screening
• History of metabolic or bone disease such as Paget's disease, rheumatoid arthritis, osteomalacia, osteogenesis imperfecta, osteopetrosis, ankylosing spondylitis, Cushing's disease, hyperprolactinemia, and malabsorption syndrome
• Vitamin D deficiency (defined as 25-OH-VitD levels < 20 ng/mL)