Therapeutic targeting of osteoclast function and pathways.

INTRODUCTION: Osteoclasts are responsible for bone resorption and underlie a number of pathological states in which osteolysis is a feature. Over recent decades our molecular understanding of osteoclast differentiation and activation has expanded significantly, and this has allowed for the development of a number of osteoclast-targeted therapies. AREAS COVERED: This review seeks to present the underlying molecular mechanisms of osteoclast differentiation and activity as a basis for understanding our current treatment of osteoporosis and malignant tumors in bone. Osteoclast-targeted therapies are also being evaluated for the treatment of rheumatoid arthritis, osteosarcoma and giant cell tumor of bone. EXPERT OPINION: With concurrent advances in the fields of molecular biology, pathology and advanced imaging, osteoclast-targeted therapies show great potential for treating conditions in which excess resorption of bone is a key pathological process. Targeting of osteoclast control mechanisms offers the potential of combining 'molecular imaging' with therapeutic intervention and longitudinal monitoring of disease processes.