Definition

A recombinant, human, immunoglobulin G4 (IgG4) monoclonal antibody directed against the receptor activator of nuclear factor kappa beta ligand (RANKL), with potential antiosteoclast and bone-sparing activities. Upon administration, anti-RANKL monoclonal antibody JMT103 specifically binds to RANKL and blocks the interaction of RANKL with RANK, a receptor located on osteoclast cell surfaces. This may inhibit osteoclast activity, decrease bone resorption, increase bone mineral density, and may protect bones from tumor metastasis. This may abrogate hypercalcemia of malignancy and may correct serum calcium levels. RANKL, a protein expressed by osteoblastic cells, plays an important role in osteoclastic differentiation and activation. Both RANKL and RANK are overexpressed in certain bone tumors, and the RANK/RANKL-mediated signaling pathway plays an important role in certain bone tumors.