Denosumab is a monoclonal antibody that blocks the action of osteoclasts, which are cells that break down bone.

However, over time, the osteoclasts tend to overtake the bone-building processes, which leads to lower bone density and a higher risk for fractures.

Myeloma cells upset this balance by promoting the activity of the destructive osteoclasts and inhibiting the work of osteoblasts, resulting in increased bone resorption.