Neoadjuvant denosumab for extensive giant cell tumor in os ischium —a case report

Open Access This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the source is credited. DOI 10.3109/17453674.2014.1002345 A 52-year-old man presented at our tertiary referral center for orthopedic oncology with progressive pain in the left hip and leg. Conventional radiographs and CT showed a relatively well-defined 8 × 9 × 11 cm expansile osteolytic lesion. The lesion extended from the left os ischium to the inferior ramus of the left os pubis (Figure 1A). MRI confirmed the presence of a highly vascularized lesion with extension into the adductor loge, obturator externus, and pectineus muscles (Figure 2A). Preoperative CT-guided core needle biopsies confirmed the diagnosis of giant cell tumor of bone (GCTB) (Figure 3A). In this patient with locally advanced GCTB at a surgically difficult anatomical location, we expected that neoadjuvant therapy with the receptor activator of nuclear factor kappa-β ligand (RANKL) inhibitor denosumab would facilitate intralesional excision by creating a calcified rim around the tumor and its soft tissue component. The patient was treated over 7 months with denosumab, 120 mg subcutaneously every 4 weeks, with loading doses at study days 8 and 15 of a large worldwide phase-2 study for patients with locally advanced GCTB (www.clinicaltrials.gov, NCT00680992). During treatment, the patient did not experience any adverse reactions. He received standard daily oral calcium/vitamin D supplementation. Serum electrolytes were checked every 4 weeks, and no evident alterations were found. 2 months after the start