Targeting Bone Metastases: New Drugs for New Targets

Bone metastases development requires multistep and multicellular machinery consisting not only of processes shared with any types of metastases (formation of a pre-metastatic niche, chemotaxis of tumor cells into the host tissue, tumor cells escape from the microvasculature), but also biological interactions that are strictly related to bone microenvironment (bone marrow colonization by cancer cells, osteomimicry, deregulation of bone homeostasis). The aim of this review is to depict the complex sequence of events from early cancer cells dissemination to the onset of clinically detectable bone lesions with particular attention to those molecular targets that have been investigated in order to find out new therapeutical approaches helpful in reducing clinical sequelae of skeletal metastases.