Effects on bone metabolism of new therapeutic strategies with standard chemotherapy and biologic drugs.

Recent biological advances have provided the framework for novel therapeutic strategies in oncology. Many new treatments are now based on standard cytotoxic drugs plus biologic agents. In Multiple Myeloma, a plasma cell neoplasm characterized by a severe bone disease, biologic drugs such as proteasome inhibitors and immunomodulatory agents, above their antineoplastic efficacy have a beneficial effects on bone disease. Bortezomib, a clinically available proteasome inhibitor active against myeloma, induces the differentiation of mesenchymal stem/progenitor cells into osteoblasts, resulting in new bone formation. Immunomodulatory drugs (e.g., thalidomide and lenalidomide), which are active against myeloma, also block the activity of bone-resorbing osteoclasts. These data reflect the utility of targeting endogenous mesenchymal stem/progenitor cells for the purpose of tissue repair and suggest that combining different classes of agents that are antineoplastic and also inhibit bone destruction and increase bone formation should be very beneficial for myeloma patients suffering from severe bone disease.