Denosumab: A Potential Treatment Option for Aneurysmal Bone Cysts (Deno-ABC)

The efficacy of traditional therapeutic approaches for aneurysmal bone cysts (ABC), such as surgery, embolization, sclerotherapy and radiotherapy, are often compromised for lesions in axial skeletons and adolescents complicated with pathological fracture. Therefore, denosumab, a new drug that has been successfully used in giant cell tumor of bone but has seldom used in ABC, was used to treat ABC in this trial.

Patients with primary ABC treated with perioperative denosumab in the Musculoskeletal Tumor Center of Peking University People's Hospital between January 2014 and December 2016 will be reported in this trial.Approved by the Ethics Committee of Peking University People's Hospital and with the full informed consent from the patients or their families, all patients received surgery and treatment with denosumab perioperatively. Denosumab 120 mg was given subcutaneously (abdomen wall or upper arms) every 4 weeks (Q4W), with a loading dose on both Day 8 and Day 15 of the first cycle. Meanwhile, all patients were suggested to take 800mg oral calcium supplement every day and avoid any dental or oral surgery (tooth extraction, tooth filling, etc.). Patients were followed once a month since the date of surgery. On follow-up visits, patient-reported adverse reactions, X-ray image of jawbone, serum calcium, alkaline phosphatase, renal and hepatic function, hemoglobin, white blood cell, and platelet count were collected, and histological examinations, radiological examinations (such as X-ray, computed tomography (CT), magnetic resonance image (MRI) and positron emission tomography-computed tomography (PET-CT) and postoperative functional status evaluations by MSTS（Musculoskeletal tumor society） score were conducted.

Patients with recurrent and/or refractory aneurysmal bone cysts treated with denosumab perioperatively.

Denosumab (Xgeva) 120 mg was given subcutaneously (abdomen wall or upper arms) every 4 weeks (Q4W), with a loading dose on both Day 8 and Day15 of the first cycle， perioperatively.

the number of participats (complete response+ partial response according to RECIST 1.1)/ total participants number.

Number of participants with abnormal laboratory values and/or adverse events that are related to the use of Denosumab（Xgeva）

include patient-reported adverse reactions, X-ray image of jawbone, serum calcium, alkaline phosphatase, renal and hepatic function, hemoglobin, white blood cell, and platelet count were collected in follow-up every 3-month.

Inclusion Criteria: pathologically diagnosed with primary aneurysmal bone cyst lesions in axial skeletons (i.e. spine, pelvis) which are difficult to reach a satisfactory surgical margin, and surgery can lead to very high incidence of complications. pathological fracture recurrence cases Exclusion Criteria: metastases or multi-focal lesions malignancy

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