Bone-targeted agents in the treatment of lung cancer.

Over a third of patients with lung cancer will develop bone metastases during the course of their disease, resulting in symptoms of pain and immobility, and skeletal-related events (SREs) such as fracture, hypercalcaemia, surgery or radiotherapy to bones, and malignant spinal cord compression. These reduce quality of life and increase mortality. Preclinical research has identified the interactions between tumour cells and bone that are key to tumour cell survival and associated osteolysis. These data have led to the development of drugs to prevent osteoclast-mediated bone breakdown, such as zoledronic acid and denosumab, which are now licensed for use in patients with bone metastases from solid tumours. Both zoledronic acid and denosumab reduce the risk of SREs and increase time to first SRE, with minimal side effects. In addition, denosumab improved survival in patients with lung cancer compared with zoledronic acid. Ongoing trials are testing whether these drugs can prevent the development of bone metastases from lung cancer. New bone-targeted agents showing promise in breast and prostate cancer include radium-223, cabozantinib and Src inhibitors. These agents require further evaluation in patients with lung cancer.