A Study to Evaluate the Safety and Efficacy of Denosumab and Ibandronate in Postmenopausal Women Sub-Optimally Treated With Daily or Weekly Bisphosphonates

Inclusion Criteria

• Ambulatory, postmenopausal women (based on medical history) 55 years or older at screening
• Postmenopause will be defined as no vaginal bleeding or spotting for at least 12 months
• If the subject is 55 - 59 years old and there is uncertainty regarding menopausal status, confirmation of serum FSH (>= 50 mIU/mL) and serum estradiol ( = 5 mg prednisone equivalent per day for more than 10 days or a total cumulative dose of >= 50 mg)
• Vitamin D deficiency [25(OH) vitamin D level < 20 ng/mL (<49.9 nmol/L)] - Repletion will be allowed and subjects may be re-screened
• Evidence of any of the following per subject report, chart review or central laboratory result:
• Significantly impaired renal function as determined by estimated Glomerular Filtration Rate less that 30mL/min/1.73 m2 determined by the central laboratory
• Current hypo- or hypercalcemia based on the central laboratory reference ranges
• Active gastric or duodenal ulcer; or any history of significant gastrointestinal bleed requiring hospitalization or transfusion
• Known to have tested positive for human immunodeficiency virus, hepatitis C virus, or hepatitis B surface antigen
• Malignancy (except fully resected cutaneous basal cell or squamous cell carcinoma, cervical or breast ductal carcinoma in situ) within the last 5 years
• Any metabolic bone disease or secondary cause of bone loss that is not controlled and may interfere with the interpretation of the findings
• Previous participation in clinical trials with denosumab 60mg SC Q6M (regardless of treatment)
• Received any solid organ or bone marrow transplant
• Any laboratory abnormality which, in the opinion of the investigator, will prevent the subject from completing the study or interfere with the interpretation of the study results
• Known sensitivity to mammalian cell derived drug products
• Known intolerance to calcium supplements
• Currently enrolled in or has not yet completed at least 1 month since ending other investigational device or drug trial(s)
• Any physical or psychiatric disorder which, in the opinion of the investigator, will prevent the subject from completing the study or interfere with the interpretation of the study results
• Evidence of alcohol or substance-abuse within the last 12 months which the investigator believes would interfere with understanding or completing the study