The purpose of this study is to describe the safety and tolerability of denosumab administration as measured by adverse events, immunogenicity, and safety laboratory parameters in subjects who previously received either zoledronic acid (Zometa®) or denosumab.

Inclusion Criteria:

• Subjects currently enrolled in study 20050103, 20050136, or 20050244
• Subjects must sign the informed consent before any study specific procedures are performed

Exclusion Criteria:

• Developed sensitivity to mammalian cell derived drug products during the 20050103, 20050136, or 20050244 study
• Currently receiving any unapproved investigational product other than denosumab
• Subject is pregnant or breast feeding, or planning to become pregnant within 7 months after the end of treatment
• Subject (male or female) is not willing to use 2 highly effective contraception during treatment and for 7 months (women) or 10 months (men) after the end of treatment
• Male subject with a pregnant partner who is not willing to use a condom during treatment and for additional 10 months after the end of treatment
• Any disorder that, in the opinion of the investigator, may compromise the ability of the subject to give written informed consent and/or comply with study procedures