Therapeutic Potential of Denosumab in Patients With Lung Cancer: Beyond Prevention of Skeletal Complications

Approximately up to 40% of patients with lung cancer develop bone metastasis, with 22% to 59% of them experiencing skeletal-related events (SREs), which result in an important quality of life deterioration and economic burden. Denosumab, a fully human antibody that targets the receptor activator of nuclear factor-κB (RANK) ligand (RANKL), is indicated for prevention of SREs in patients with solid tumors and has demonstrated superiority in breast and prostate cancer, and in other solid tumors, in reducing the risk of first SRE by 17% versus zoledronic acid. In the subset of patients with non-small-cell lung carcinoma (NSCLC), denosumab has also shown a positive trend to SRE risk reduction. Denosumab might have direct or indirect antitumor effects. Cancer cells produce factors that stimulate increased bone resorption by osteoclasts, which in turn release tumor growth factors into the bone microenvironment, initiating a tumor/bone vicious cycle. An increasing body of evidence suggests RANK/RANKL signaling plays a role in this tumorigenesis. Both proteins are overexpressed in different tumor types including lung cancer cells. RANK/RANKL signaling activates nuclear factor-κB pathways related to lung carcinogenesis and increases intercellular adhesion molecule 1 expression and MEK/extracellular signal-regulated kinase phosphorylation, which in turn enhances tumor cell migration. In animal NSCLC models, denosumab delayed bone metastases and reduced skeletal tumor growth. In patients with lung cancer (post hoc analysis), denosumab prolonged overall survival by 1.2 months versus zoledronic acid (P = .01). This hypothesis-generating outcome warrants further investigation and 2 studies in lung cancer are ongoing to elucidate the therapeutic potential of denosumab beyond SRE prevention.