Daniel G. Branstetter, from Amgen Inc. in Seattle, and colleagues histologically analyzed GCTB tumor samples from adult patients with recurrent or unresectable GCTB participating in a phase II study of denosumab. Patients received subcutaneous denosumab 120 mg every four weeks (with additional doses on days eight and 15).

The researchers found that baseline tumor samples were typically composed of densely cellular proliferative RANK ligand (RANKL)-positive stromal cells, RANK-positive rounded mononuclear cells, abundant RANK-positive tumor giant cells, and areas of scant de novo osteoid matrix and woven bone. In 100 percent of patients (20 of 20) there was a decrease of 90 percent or more in tumor giant cells and a reduction in tumor stromal cells seen in on-study samples. There was an increased proportion of dense fibro-osseous tissue and/or new woven bone replacing areas of proliferative RANKL-positive stromal cells in 13 patients (65 percent).

"Denosumab treatment of patients with GCTB significantly reduced or eliminated RANK-positive tumor giant cells," the authors write.

Several authors disclosed financial ties to Amgen Inc., which funded the study.

Abstract
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