Inclusion Criteria:
* Participant has provided informed consent prior to initiation of any study specific activities/procedures.
* Chinese male or female adults aged ≥ 18 years or skeletally mature adolescents (ie, radiographic evidence of at least 1 mature long bone \[eg, humerus with closed growth epiphyseal plate\]) ≥ 12 years of age.
* Skeletally mature adolescents must weigh at least 45 kg.
* Pathologically confirmed giant cell tumor of bone (GCTB) within 1 year before study enrollment (central pathology review).
* Measurable evidence of active disease within 1 year before study enrollment.
* Participants with surgically unsalvageable disease (eg, sacral, spinal GCTB, or multiple lesions including pulmonary metastases) OR participants whose planned surgery includes joint resection, limb amputation, hemipelvectomy or surgical procedure resulting in severe morbidity.
* Eastern Cooperative Oncology Group performance status (\[ECOG PS\] of ≤ 2).
Exclusion Criteria:
* Known or suspected current diagnosis of underlying malignancy including high-grade sarcoma, osteosarcoma, fibrosarcoma, malignant giant cell sarcoma.
* Known diagnosis of malignancy derived from non-musculoskeletal system within the past 5 years (participants with definitively treated basal cell carcinoma and cervical carcinoma in situ are permitted).
* Known or suspected current diagnosis of brown cell tumor of bone or Paget's disease.
* Known or suspected current diagnosis of non GCTB giant cell-rich tumors.
* Prior history or current evidence of osteonecrosis/osteomyelitis of the jaw.
* Active dental or jaw condition which requires oral surgery, including tooth extraction.
* Non-healed wound after dental/oral surgery.
* Planned invasive dental procedure for the course of the study.
* Any planned treatment with intravenous (IV) or oral bisphosphonates during the study.
* Currently receiving other GCTB-specific treatment (eg, radiation, chemotherapy, or embolization).
* Current or previous XGEVA treatment
* Concurrent bisphosphonate treatment
* Currently receiving treatment in another investigational device or drug study, or less than 30 days since ending treatment on another investigational device or drug study(ies). Other investigational procedures while participating in this study are excluded.
* Female participant is pregnant or breastfeeding or planning to become pregnant or breastfeed during treatment and for an additional 5 months after the last dose of XGEVA.
* Female participants of childbearing potential unwilling to use 2 highly effective method of contraception or acceptable method of effective contraception during treatment and for an additional 5 months after the last dose of XGEVA.
* Female participants of childbearing potential with a positive pregnancy test assessed at screening by a serum pregnancy test and/or urine pregnancy test.
* Male participants with a female partner of childbearing potential who are unwilling to practice sexual abstinence (refrain from heterosexual intercourse) or use contraception during treatment and for an additional 5 months after the last dose of XGEVA.
* Male participants with a pregnant partner who are unwilling to practice abstinence or use a condom during treatment and for an additional 5 months after the last dose of XGEVA.
* Male participants unwilling to abstain from donating sperm during treatment and for an additional 5 months after the last dose of XGEVA.
* Participant has known sensitivity to any of the products to be administered during dosing.
* Participant likely to not be available to complete all protocol-required study visits or procedures, and/or to comply with all required study procedures (eg, Clinical Outcome Assessments) to the best of the participant and investigator's knowledge.
* Unstable systemic disease including active infection, uncontrolled hypertension, unstable angina, congestive heart failure, or myocardial infarction within 6 months before enrollment.
* History or evidence of any other clinically significant disorder, condition or disease (with the exception of those outlined above) that, in the opinion of the investigator or Amgen physician, if consulted, would pose a risk to participant safety or interfere with the study evaluation, procedures or completion.
* Participant has any kind of disorder that compromises the ability of the participant to give written informed consent and/or to comply with study procedures.
