Bone complications in multiple myeloma.

Multiple myeloma is the malignant proliferation of plasma cells involving more than 10% of the bone marrow. The bone complications associated with multiple myeloma include bone pain, pathologic fractures, hypercalcemia of malignancy and cord compressions. The principal pathophysiology of bone disease in multiple myeloma is a shift in the balance of bone remodeling toward bone resorption. In recent years, bisphosphonates have become an important treatment for the bone complications of multiple myeloma. Potent inhibitors of osteoclast activity, bisphosphonates interfere with biochemical pathways and induce osteoclast apoptosis. Bisphosphonates also antagonize osteoclastogenesis and promote differentiation of osteoblasts, as well as inhibiting other aspects of osteoclast homeostasis and metabolism. Several studies have evaluated treatment with bisphosphonates in patients with multiple myeloma, and have demonstrated the efficacy of clodronate (Bonefos; Anthra Pharmaceuticals; Princeton, NJ; www.bonefos.com), pamidronate (Aredia; Novartis Pharmaceuticals Corp; East Hanover, NJ; www.pamidronate.com) and zoledronic acid (Zometa; Novartis Pharmaceuticals Corp; East Hanover, NJ; www.us.zometa.com) in reduction of pain, reduction of SREs and survival. Moreover, recent data suggest direct and indirect antimyeloma activity of pamidronate and zoledronic acid.