Bone metastases are the result of a primary tumour invading the bone and generally arise from epithelial tumours and form a solid mass within the bone. Bone metastases maybe very painful with pain presenting as a constant dull ache with occasional spikes of intense pain.  It is thought that one of the causes of pain is the lowering of pH, which produces an acidic environment triggering pain receptors.  Metastases can also cause fractures of the bone and in some cases compression of the spinal cord. Bone is the third most common place for metastases after the lung and the liver.

Treatment is mainly palliative in an effort to control the pain. Bisphosphonates are used to strengthen bone and prevent fractures.  Getting pain control drugs or anti-cancer agents into the bone is difficult given the hard surface and low porosity of bone.  Mesentech believes that its bone targeting and drug delivery technology may prove effective in delivering appropriate therapeutic agents into the bone in order to treat the metastases and provide pain relief.