Myeloma bone disease: pathogenesis and treatment.

Bone involvement manifesting as osteolytic bone disease (OBD) or osteopenia is one of the defining features of multiple myeloma (MM). Osteolytic lesions develop in nearly 90% of patients with MM, and these are frequently complicated by skeleton-related events (SREs) such as severe bone pain, pathologic fractures, vertebral collapse, hypercalcemia, and spinal cord compression. SREs have a negative effect on patients' quality of life and affect their long-term outcomes, including survival. In MM, the delicate balance between bone formation and bone destruction is perturbed. OBD is a consequence of increased osteoclast activation along with osteoblast inhibition, which alter bone remodeling. Although MM remains incurable, tremendous progress has been made in the treatment of the disease. As such, there is a need to address the symptoms of the disease that affect quality of life and, ultimately, overall survival. Novel agents targeting OBD are promising therapeutic strategies not only for the treatment of MM OBD but also for the treatment of MM itself. In addition to bisphosphonates, several novel agents are currently under investigation for their positive effect on bone remodeling via osteoclast inhibition or osteoblast stimulation. Future studies will look to combine or sequence all of these agents to improve quality of life, decrease the symptoms of MM OBD, and enhance antitumor activity.